CA1079296A - Iso- or terephthalic preparation in a benzoic acid-water solvent system - Google Patents
Iso- or terephthalic preparation in a benzoic acid-water solvent systemInfo
- Publication number
- CA1079296A CA1079296A CA282,898A CA282898A CA1079296A CA 1079296 A CA1079296 A CA 1079296A CA 282898 A CA282898 A CA 282898A CA 1079296 A CA1079296 A CA 1079296A
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- Prior art keywords
- xylene
- water
- oxidation
- benzoic acid
- solvent system
- Prior art date
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Classifications
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/16—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation
- C07C51/21—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen
- C07C51/255—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen of compounds containing six-membered aromatic rings without ring-splitting
- C07C51/265—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen of compounds containing six-membered aromatic rings without ring-splitting having alkyl side chains which are oxidised to carboxyl groups
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
- Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
Abstract
ISO- OR TEREPHTHALIC PREPARATION IN A
BENZOIC ACID-WATER SOLVENT SYSTEM
ABSTRACT OF DISCLOSURE
The present invention relates to the preparation of iso- or terephthalic acid by the oxidation of m- or p-xylene with molecular oxygen at elevated temperatures and under liquid phase conditions in the presence of catalysis provided by a combination of one or more transition metal oxidation catalysts and a source of bromine improved by the use of a liquid solvent system consisting essentially of benzoic acid and at least 3 percent and up to about 15 percent by weight of water which provides commercially feasible control of oxidation temperature not otherwise feasible in the absence of the water component of said catalyst system when said xylenes are oxidized.
BENZOIC ACID-WATER SOLVENT SYSTEM
ABSTRACT OF DISCLOSURE
The present invention relates to the preparation of iso- or terephthalic acid by the oxidation of m- or p-xylene with molecular oxygen at elevated temperatures and under liquid phase conditions in the presence of catalysis provided by a combination of one or more transition metal oxidation catalysts and a source of bromine improved by the use of a liquid solvent system consisting essentially of benzoic acid and at least 3 percent and up to about 15 percent by weight of water which provides commercially feasible control of oxidation temperature not otherwise feasible in the absence of the water component of said catalyst system when said xylenes are oxidized.
Description
`` 10'79Z~f~
Background of Invention The unique catalysis provided by a combination of one or more transistion metal oxidation catalysts and a source of bromine has been taught by United States Patent No. 2,833,816 and the commonly derived foreign patent counterparts as general-ly applicable for the preparation of aromatic carboxylic acids at elevated temperatures in the range of 50 to 275C and under pressures to maintain liquid phase conditions for the oxidation with a source of molecular oxygen of aromatic hydrocarbons having at least one substituent oxidizable to a carboxylic acid substituent. Said patents also taught the use of C2-C8 carboxylic acids as useful for such catalytic liquid phase oxidations.
Such catalytic liquid phase oxidation has been developed into the predominant world-wide commercial production of lSO-phthalic acid, terephthalic acid and trimellitic acid by the respective air oxidations of m-xylene, p-xylene and pseudocumene in the presence of acetic acid. Such catalytic liquid phasè
oxidation has also been applied to the commercial production of benzoic acid, but of lower magnitude, by the air oxidation of toluene in the presence of benzoic acid as solvant.
The use of acetic acid as solvent in such commercial ~
production of the benzene di- and tricarboxylic acid products, ;~`
although providing a most economically advantageous process, ;~-does have the disability of co-oxidation of acetic acid to the extent of from 80 to 160 kilograms per metric ton (MT) of pro-duct produced. Acetic acid, the most refractory of the C2-C
aliphatic acid class, is oxidatively converted in such processes `
to oxides of carbon, water and methyl acetate.
Temperature control of such oxidations conducted in the presence of acetic acid solvent presents no commercial operating ~b. ' ~ ' .. : - . . . .. . . . . .
-" 1079Z96 problem because of the relatively close boiling points of acetic acid and by-product water and the water concentrations, 3 to 18 weight percent of solvent, involved. Such acetic acid-water solvent system for practical consideration is a one component system of miscible liquids and has from phase rule relationships but one degree of freedom. Thus, for constant volume operation, setting operating pressure as a constant provides a constant operating temperature.
In 1963, a continuous process was disclosed for the pre-paration of benzene di- and tricarboxylic acids, especially tere-phthalic acid, by the catalytic liquid phase air oxidation of the appropriate methyl-substituted benzene in the presence of benzoic acid, in place of acetic acid, as reaction solvent and in the presence of the earlier disclosed unique combination of one or more transition metal oxidation catalysts and a source of bromine. British Patent Specification No. 1,088,183, pub-lished 25 October 1967, is directed to and contains details of such oxidations conducted in the presence of benzoic acid solvent. According to said patent, benzoic acid was selected over the other C2-C8 monocarboxylic acids because its aeration I` at temperatures in the 50-275C range produced a medium less i corrosive to metals available for fabrication of oxidation vessels than aerated acetic acid at such temperatures, it was less volative than acetic acid, and by-product water vapor was more readily separated from benzoic acid vapor than from ~ acetic acid vapor at the reaction site. For example, selective 'i condensation of benzoic acid vapors from a vapor mixture thereof with by-product water can be accomplished by simple partial i condensation but separation of a mixture of acetic acid and by-product water vapors require fractionation.
Further benefits from the use of benzoic acid solvent, according to the British Patent, come from the use of high, 170 ' ~: ''' :', :
~ - 1079~96 to 275C, oxidation temperatures which provide high oxidation rates; the use of high, 21 to 35 kg/cm , operating gauge pres-sures which provide high oxygen concentrations in the liquid phase reaction medium; the required removal of by-product water as it is formed; and the independence of operating temperature on such operating pressure.
The above British Patent provides three continuous air oxidations of p-xylene to terephthalic acid wherein its yields of 85-95 mole percent (% of theory) and purity of 99-99.9 wèight ~ 10 percent are illustrated.
- However, in spite of such promised high yields and purity of terephthalic acid prepared in the presence of liquid benzoic acid solvent, we have found a major problem associated ~; with the conduct of the continuous process of said British , Patent.
i Said problem was found to occur during initiation of the p-xylene oxidation at the operating gauge pressure of 21 to 35 kg/cm2 while removing by-product water as it was formed.
At such oxidation initiation conditions the operating temper- ~ -ature could not be controlled and the benzoic acid and/or p-xylene or its partial oxidation products were quite rapidly ;
over oxidized to a carbonaceous residue. The lack of stirring of the liquid phase composition, the illustrative examples in the British Patent did not use a stirred-tank type oxidation vessel, could lead to inefficient dispersion of air and distribution of heat of reaction in the liquid phase and thus . .
I provide localized "hot spots", the isolated high oxidation . ~ . .
rate resulting from highly localized conditions of high temper-ature and oxygen concentration. But unstirred tubular reaction vessels had been successfully used for other oxidations; for example, the preparation of benzoic acid by air oxidation of _ 4 _ ~, ,.
,~ ' . ~ .. . .
10'79Z96 :
,~
toluene in the presence of benzoic acid solution of a combina-tion of one or more transition metal and a source of bromine, without encountering such sudden charring of reactant, product or benzoic acid solvent. Hence, the lack of stirring was not the controlling effect with respect to the problem of rapid char formation from the inability to control temperature during initiation of p-xylene oxidation.
We found that the effects causing the rapid charring during oxidation initiation to be associated with the required high operating gauge pressure of 21 to 35 kg/cm2 and removal of by-product water as it is formed. This discovery resulted from our investigation of the effect of retention or lack thereof '~ of small amounts of water in the benzoic acid solvents on the control of initial operating temperature of the 21 to 35 kg/cm2 operating gauge pressure required according to the process of the British Patent.
By experimentation it was found that by going from 5 , weight percent to 0 weight percent water concentration of liquid benzoic acid under a gauge pressure of 25-35 kg/cm2 and an - -l~20 initial temperature of 205C a temperature increase of as much ;~I as 110C was observed without change of pressure.
Substantiation of such effects causing the rapid charring can be understood from the results of the following investigations.
Benzoic acid (boiling point of 249C at 760 mm Hg) with a water content of 5 weight percent was heated to an initial temperature ~ of 205C under a gauge pressure set at 21 to 35 kg/cm2. The !~ temperature of the liquid benzoic acid was measured as its water content went from the initial 5% down to 0%. By going from 5%
to 0% water the temperature of the liquid benzoic acid increased as much as 110C without causing an increase in the set gauge pressure. This indicated a unique temperature sensitivity ?
.' , -,: ~
with respect to water content of liquid benzoic acid solvent and accounted for the rapid drastic over oxidation to a charred product during initiation of p-xylene oxidation at a gauge pressure of 21 to 35 kg/cm2 following the required operating conditions of the British Patent.
Based on our discovery from the dramatic temperature in-creases found during our foregoing experiments we concluded that removing by-product water as rapidly as formed to maintain a near 0 water content and conducting at least the oxidation initiation under a pressure as high as 21 to 35 kg/cm could not lead to successful temperature control necessary for ~
commercial operation of the product of iso- or terephthalic -acid from the air oxidation of m- or p-xylene in the presence of liquid benzoic acid as reaction solvent.
Another problem arose beyond initiation of the continuous oxidation of m- or p-xylene with air in the presence of liquid , benzoic acid as a solvent according to the operating conditions of the British Patent. After the oxidation had been success-fully initiated in the stirred liquid phase with good tempera-, 20 ture control provided by the proper initial and retained water `, content of the liquid benzoic acid, there were still wide :! :
fluctuations in react1on temperature caused by changes in the amount of water removed. This and the foregoing experimental results led us to conclude that the 21 to 35 kg/cm operating pressure imposed by the British Patent was too high and the required removal of by-product water as rapidly as formed was unnecessary and would not provide a commercially acceptable ~, continuous process.
Statement of the Invention We have found that control of operating temperature for both initiation and lined-out operation for a commercially . : .
.
.: . : :. .: .
.
' ' .
acceptable continuous air oxidation of m- or p-xylene can be ' achieved. Thus the present invention provides a process of ,~- preparing iso- or terephthalic acid by the liquid phase oxidation ;` of m- or p-xylene with air in an oxidation zone at an elevated ~ temperature of up to 275C in the presence of a monocarboxylic ,;
~, acid solution of catalysis components comprising a source of , bromine and one or more transition metal oxidation catalyst ,~ .:
maintained as a liquid at said temperature by elevated oxidation zone pressure.
~i 10 This process is characterized by conducting the air oxidation of m- or p-xylene in a semi-continuous or continuous - manner in a stirred oxidation zone containing said catalysis .,; . .
si wherein the transition metal component is manganese or a com-bination of manganese with one or both of cobalt and cerium in a solvent system consisting essentially of liquid benzoic ,',:! acid and water and at an oxidation zone temperature maintained . .
substantially constant at a selected temperature within the ~ :
temperature range of 175 to 235C by maintaining (a) the solvent system components within the range of 85 to 97 weight percent .,~
benzoic acid and 15 to 3 weight percent water, (b) the oxida-`~l tion zone gauge pressure within the range of 6 to 25 kg/cm2,~'s and (c) the removal of by-product water as vapor by cooling the exhaust from the oxidation zone to condense benzoic acid "~ from reflux thereto and varying the amount of water returned ,' to limit fluctuation of oxidation zone temperature to +5C from the selected temperature wherein said oxidation zone the weight ratio of such solvent system to said xylene is in the range of
Background of Invention The unique catalysis provided by a combination of one or more transistion metal oxidation catalysts and a source of bromine has been taught by United States Patent No. 2,833,816 and the commonly derived foreign patent counterparts as general-ly applicable for the preparation of aromatic carboxylic acids at elevated temperatures in the range of 50 to 275C and under pressures to maintain liquid phase conditions for the oxidation with a source of molecular oxygen of aromatic hydrocarbons having at least one substituent oxidizable to a carboxylic acid substituent. Said patents also taught the use of C2-C8 carboxylic acids as useful for such catalytic liquid phase oxidations.
Such catalytic liquid phase oxidation has been developed into the predominant world-wide commercial production of lSO-phthalic acid, terephthalic acid and trimellitic acid by the respective air oxidations of m-xylene, p-xylene and pseudocumene in the presence of acetic acid. Such catalytic liquid phasè
oxidation has also been applied to the commercial production of benzoic acid, but of lower magnitude, by the air oxidation of toluene in the presence of benzoic acid as solvant.
The use of acetic acid as solvent in such commercial ~
production of the benzene di- and tricarboxylic acid products, ;~`
although providing a most economically advantageous process, ;~-does have the disability of co-oxidation of acetic acid to the extent of from 80 to 160 kilograms per metric ton (MT) of pro-duct produced. Acetic acid, the most refractory of the C2-C
aliphatic acid class, is oxidatively converted in such processes `
to oxides of carbon, water and methyl acetate.
Temperature control of such oxidations conducted in the presence of acetic acid solvent presents no commercial operating ~b. ' ~ ' .. : - . . . .. . . . . .
-" 1079Z96 problem because of the relatively close boiling points of acetic acid and by-product water and the water concentrations, 3 to 18 weight percent of solvent, involved. Such acetic acid-water solvent system for practical consideration is a one component system of miscible liquids and has from phase rule relationships but one degree of freedom. Thus, for constant volume operation, setting operating pressure as a constant provides a constant operating temperature.
In 1963, a continuous process was disclosed for the pre-paration of benzene di- and tricarboxylic acids, especially tere-phthalic acid, by the catalytic liquid phase air oxidation of the appropriate methyl-substituted benzene in the presence of benzoic acid, in place of acetic acid, as reaction solvent and in the presence of the earlier disclosed unique combination of one or more transition metal oxidation catalysts and a source of bromine. British Patent Specification No. 1,088,183, pub-lished 25 October 1967, is directed to and contains details of such oxidations conducted in the presence of benzoic acid solvent. According to said patent, benzoic acid was selected over the other C2-C8 monocarboxylic acids because its aeration I` at temperatures in the 50-275C range produced a medium less i corrosive to metals available for fabrication of oxidation vessels than aerated acetic acid at such temperatures, it was less volative than acetic acid, and by-product water vapor was more readily separated from benzoic acid vapor than from ~ acetic acid vapor at the reaction site. For example, selective 'i condensation of benzoic acid vapors from a vapor mixture thereof with by-product water can be accomplished by simple partial i condensation but separation of a mixture of acetic acid and by-product water vapors require fractionation.
Further benefits from the use of benzoic acid solvent, according to the British Patent, come from the use of high, 170 ' ~: ''' :', :
~ - 1079~96 to 275C, oxidation temperatures which provide high oxidation rates; the use of high, 21 to 35 kg/cm , operating gauge pres-sures which provide high oxygen concentrations in the liquid phase reaction medium; the required removal of by-product water as it is formed; and the independence of operating temperature on such operating pressure.
The above British Patent provides three continuous air oxidations of p-xylene to terephthalic acid wherein its yields of 85-95 mole percent (% of theory) and purity of 99-99.9 wèight ~ 10 percent are illustrated.
- However, in spite of such promised high yields and purity of terephthalic acid prepared in the presence of liquid benzoic acid solvent, we have found a major problem associated ~; with the conduct of the continuous process of said British , Patent.
i Said problem was found to occur during initiation of the p-xylene oxidation at the operating gauge pressure of 21 to 35 kg/cm2 while removing by-product water as it was formed.
At such oxidation initiation conditions the operating temper- ~ -ature could not be controlled and the benzoic acid and/or p-xylene or its partial oxidation products were quite rapidly ;
over oxidized to a carbonaceous residue. The lack of stirring of the liquid phase composition, the illustrative examples in the British Patent did not use a stirred-tank type oxidation vessel, could lead to inefficient dispersion of air and distribution of heat of reaction in the liquid phase and thus . .
I provide localized "hot spots", the isolated high oxidation . ~ . .
rate resulting from highly localized conditions of high temper-ature and oxygen concentration. But unstirred tubular reaction vessels had been successfully used for other oxidations; for example, the preparation of benzoic acid by air oxidation of _ 4 _ ~, ,.
,~ ' . ~ .. . .
10'79Z96 :
,~
toluene in the presence of benzoic acid solution of a combina-tion of one or more transition metal and a source of bromine, without encountering such sudden charring of reactant, product or benzoic acid solvent. Hence, the lack of stirring was not the controlling effect with respect to the problem of rapid char formation from the inability to control temperature during initiation of p-xylene oxidation.
We found that the effects causing the rapid charring during oxidation initiation to be associated with the required high operating gauge pressure of 21 to 35 kg/cm2 and removal of by-product water as it is formed. This discovery resulted from our investigation of the effect of retention or lack thereof '~ of small amounts of water in the benzoic acid solvents on the control of initial operating temperature of the 21 to 35 kg/cm2 operating gauge pressure required according to the process of the British Patent.
By experimentation it was found that by going from 5 , weight percent to 0 weight percent water concentration of liquid benzoic acid under a gauge pressure of 25-35 kg/cm2 and an - -l~20 initial temperature of 205C a temperature increase of as much ;~I as 110C was observed without change of pressure.
Substantiation of such effects causing the rapid charring can be understood from the results of the following investigations.
Benzoic acid (boiling point of 249C at 760 mm Hg) with a water content of 5 weight percent was heated to an initial temperature ~ of 205C under a gauge pressure set at 21 to 35 kg/cm2. The !~ temperature of the liquid benzoic acid was measured as its water content went from the initial 5% down to 0%. By going from 5%
to 0% water the temperature of the liquid benzoic acid increased as much as 110C without causing an increase in the set gauge pressure. This indicated a unique temperature sensitivity ?
.' , -,: ~
with respect to water content of liquid benzoic acid solvent and accounted for the rapid drastic over oxidation to a charred product during initiation of p-xylene oxidation at a gauge pressure of 21 to 35 kg/cm2 following the required operating conditions of the British Patent.
Based on our discovery from the dramatic temperature in-creases found during our foregoing experiments we concluded that removing by-product water as rapidly as formed to maintain a near 0 water content and conducting at least the oxidation initiation under a pressure as high as 21 to 35 kg/cm could not lead to successful temperature control necessary for ~
commercial operation of the product of iso- or terephthalic -acid from the air oxidation of m- or p-xylene in the presence of liquid benzoic acid as reaction solvent.
Another problem arose beyond initiation of the continuous oxidation of m- or p-xylene with air in the presence of liquid , benzoic acid as a solvent according to the operating conditions of the British Patent. After the oxidation had been success-fully initiated in the stirred liquid phase with good tempera-, 20 ture control provided by the proper initial and retained water `, content of the liquid benzoic acid, there were still wide :! :
fluctuations in react1on temperature caused by changes in the amount of water removed. This and the foregoing experimental results led us to conclude that the 21 to 35 kg/cm operating pressure imposed by the British Patent was too high and the required removal of by-product water as rapidly as formed was unnecessary and would not provide a commercially acceptable ~, continuous process.
Statement of the Invention We have found that control of operating temperature for both initiation and lined-out operation for a commercially . : .
.
.: . : :. .: .
.
' ' .
acceptable continuous air oxidation of m- or p-xylene can be ' achieved. Thus the present invention provides a process of ,~- preparing iso- or terephthalic acid by the liquid phase oxidation ;` of m- or p-xylene with air in an oxidation zone at an elevated ~ temperature of up to 275C in the presence of a monocarboxylic ,;
~, acid solution of catalysis components comprising a source of , bromine and one or more transition metal oxidation catalyst ,~ .:
maintained as a liquid at said temperature by elevated oxidation zone pressure.
~i 10 This process is characterized by conducting the air oxidation of m- or p-xylene in a semi-continuous or continuous - manner in a stirred oxidation zone containing said catalysis .,; . .
si wherein the transition metal component is manganese or a com-bination of manganese with one or both of cobalt and cerium in a solvent system consisting essentially of liquid benzoic ,',:! acid and water and at an oxidation zone temperature maintained . .
substantially constant at a selected temperature within the ~ :
temperature range of 175 to 235C by maintaining (a) the solvent system components within the range of 85 to 97 weight percent .,~
benzoic acid and 15 to 3 weight percent water, (b) the oxida-`~l tion zone gauge pressure within the range of 6 to 25 kg/cm2,~'s and (c) the removal of by-product water as vapor by cooling the exhaust from the oxidation zone to condense benzoic acid "~ from reflux thereto and varying the amount of water returned ,' to limit fluctuation of oxidation zone temperature to +5C from the selected temperature wherein said oxidation zone the weight ratio of such solvent system to said xylene is in the range of
2 to 10:1.0, said components of catalysis in the solvent system are present in the amounts of 0.2 to 1.5 weight percent total metal and 0.2 to 1.5 weight percent bromine based on the xylene l with a weight ratio of bromine to total metal in the range of ..
: ~ 7 -,, . -,.. , . , ~. .... . ~ : ~
---" 1079296 0.5 to 2.5 weight parts of bromine for each part by weight total metal and the ratio of air to xylene fed to said zone provide an exhaust gas therefrom containing 3 to 10 volume percent oxygen. ~ -In one aspect such a process is described wherein p-xylene is oxidized with air and the transition metal component of catalysis is provided by manganese and cobalt in the Mn/Co -weight ratio of from 1:1 to 6:1 and the sum of Mn and Co metal weights are within the 0.5 to 1.5 weight percent of p-xylene.
In a preferred embodiment such a process is provided wherein ~
the solvent system consists essentially of 90% benzoic acid - -and 10% water, the weight ratio of the solvent system to p-xylene is 2 to 7:1, the components of catalyst are in the concentrations of 0.015 to 0.1% cobalt, 0.08 to 0.2% manganese and 0.02 to 0.3% bromine based on said solvent, the oxidation zone tempera- ~;
ture is from 205 to 226.5C, the oxidation zone gauge pressure ~ -is from 14-24.6 kg/cm2, and the oxygen content of the exhaust ~
;~ gas is from 6-10 volume percent. -In a further aspect such an invention is provided wherein p-xylene is oxidized with air, the solvent system consists essentially of 90% benzoic acid and 10% water, the weight ratio of solvent system to p-xylene is 3-5:1.0, and the transition metal component of catalysis is manganese and the ratio of bromine to manganese is from 0.8 to 1.5:1.0 and the manganese concentration is from 0.15 to 0.2 weight percent of solvent.
In a preferred embodiment the operating temperature fluctuation limited to not more than -~ 5C from a selected constant pressure by varying the rate of water condensate re-turned to the oxidation zone.
For such continuous oxidation the unique catalysis of a combination of one or more transition metal oxidation catalyst and a source of bromine is provided by dissolving suitable souces .. : ~ ,. ..,, ~, . . .
.. . . . . . . .. .
` 10792~6 of the components in the solvent system.
The present inventive continuous process is conducted in a stirred oxidation zone to provide efficient dispersion of air in and distribution of heat of reaction through the liquid phase in the oxidation zone.
The heat of reaction will cause vaporization of a little benzoic acid and mainly water from the oxidation zone. Little or no xylene is vaporized because it is oxidized to products which do not tend to be vaporized at the operating conditions.
Satisfactory temperature control is achieved for substantially constant operating conditions by regulating the water content of the liquid reflux (mainly water) to the oxidation zone after ;
~ the condensation of said vapors to remove heat of reaction.
; The water content of the liquid reflux, generally 90-95 weight percent, can be regulated by the operating temperature of the reflux condenser. Change in oxidation temperature from a selected constant operating temperature can be corrected by varying the rate of addition of water (since the condensate ; has only 5-10 weight ~ benzoic acid) returned to the oxidation~20 zone. For example, the rate of water return by way of the re-flux liquid is decreased or increased in response to a decrease or increase of oxidation zone temperature from the selected constant temperature. Means for such variation of water con- -tent of liquid reflux and rate of water return to the oxidation zone are hereafter described. Such means can keep the change of oxidation zone temperature within 5C above or below the selected constant temperature for the oxidation zone.
The variation of water rate of such returned liquid should not decrease the water content of the solvent system below 3 weight percent because at such condition the uncontrolled wide temperature fluctuation conditions again occur. The variation ,' _ g _ --'` 10792~6 of such returned liquid should not increase the water content of the solvent system above about 15 weight percent, e.g. to 18 weight percent, because such amount of water deactivates the system of catalysis partially or completely to make the oxida-tion rate commercially unattractive.
For the purposes of this invention the m- or p-xylene oxidation is carried out with a weight ratio of the benzoic acid-water solvent system to xylene in the range of 2:1 to 10 Also, the system of catalysis is suitably provided by a source of bromine in combination with one or more of manganese, cobalt, ~ ~
or cerium as transition metal oxidation catalyst. Also, it is ~ -preferred to use an amount of air which provides from 2 up to 10 volume percent oxygen in the exhaust gas (benzoic acid-free basis) to minimize the amount of partial oxidation products and color body impurities in the iso- or terephthalic acid product recovered.
Operation of the present inventive process is conducted on a continuous basis for the combination of 6-25 kg/cm2 gauge pressure and the particular benzoic acid-water solvent system to proyide for efficient control of substantially constant tem-perature in the oxidation zone in the operating temperature ~ ~ .
range of 175-235C.
The continuous operation of the present inventive process ;;
does not have relatively high xylene concentration at start-up; -i.e., initiation of oxidation, as will be understood from the start-up procedure for continuous operation. Said start-up differs from batchwise operation in that there is initially charged to the stirred oxidation zone the components of the -unique catalysis and solvent system. The resulting solution is stirred and heated to a temperature at which oxidation is initi-ated, e.g., 160-170C, but preferably to operating temperature .
~1 .
, --``` 1079Z~
of 175-235C. When such heating is only to oxidation initiation temperature, then m- or p-xylene is pumped into the stirred liquid in the oxidation zone and air is injected into said stirred liquid at about 1000-1500 N liters per kilogram of xylene until the oxidation zone temperature reaches the oper-ating temperature selected from 175-235C. Thereafter the xylene is pumped into the oxidation zone and air rate is in-creased to the range of from about 3800 to about 5900 N liters per kilogram of xylene to provide the 3-10 volume percent oxygen in the exhaust gas (benzoic acid and water-free basis). After the weight ratio of originally charged solvent system to the total xylene charged reaches the selected ratio in the range of 3-10:1.0, the solution of catalyst components in the benzoic acid-water solvent system is pumped in at a rate with respect to continued xylene pumping to preserve the selected solvent to xylene weight ratio as the injection of air is continued at said 3800-5900 N l/kg xylene providing such 3-10 volume percent oxygen in the exhaust gas. The time for such initiation to complete continuous feed operation is relatively short but does provide time to adjust the operation of the condenser to which the exhaust gas is conducted for removing heat of reaction and adjust the rate of water condensate returned with liquid condensate reflux to the stirred oxidation zone. Upon reaching the operating aerated liquid volume of the oxidation zone, the fluid oxidation reaction mixture is then withdrawn from the oxidation zone to supply feed to the separation of iso~
or terephthalic acid product from liquid benzoic acid-water sol-vent system. --Although such operation from initiation through complete continuous operation introducing reactants and solvent system solution of catalysis and withdrawing fluid reaction mixture ~79296 is not preferred, it does serve as a useful start-up procedure ;
to gain experience with the unique temperature sensitivity -with respect to water content of the solvent system having the most pronounced effect on successful control of operating temperature.~ - -After such experience is gained then the start-up of the present inventive process can be simplified by resorting to the preferred start-up conditions. For the preferred start-up, the solvent system solution of components of catalyst needed to -~
reach operating volume of the reactor is charged and stirred and heated to the selected operating temperature under the selected operating pressure. Thereafter the xylene is pumped ~-in and air is injected into the stirred solvent at continuous ;~
operating rates with the condenser reflux system operating in response to the temperature of the oxidation zone. Removal of fluid is started when the total xylene charged provides, with respect to initial solvent system charged, the selected weight ratio of solvent system to xylene.
The continuous operation of the present inventive process ' 20 can be conducted in an oxidation vessel having a stirrer, a Z reflux condenser operated at a temperature of about the melting -` point of benzoic acid (121.7C) to condense benzoic acid as a liquid for reflux to the stirred oxidation zone and a side arm- -type condenser operated to condense water vapor for removal of by-product water. A pressure control valvè can be used between said condensers or preferably after the water vapor condenser, for example at the exit therefrom. Uncondensed gases can be ~I discharged from said condensate collecting vessel through the pressure reducing valve. The reaction vessel should be fitted with temperature and pressure measuring devices and means for charging reactants, solvent solution of components of catalysis, - 10~;~9296 and withdrawing fluid oxidation effluent. With such combina-tion of apparatus elements control of water content of the benzoic acid-water solvent system can be readily monitored and control-led within the 3-15 weight percent water content on the basis of a water material balance. Only a metered amount of water condensate is discarded which is equivalent to the amount of by-product water produced and the remainder of the condensate is pumped back into the reaction zone to control the oxidatibn zone at constant pressure.
Product iso- or terephthalic acid, relatively insoluble -in the solvent system, can be separated from the fluid oxida-tion effluent by any solid-liquid separation means such as by ;
filtxation or centrifugation, at a temperature at which benzoic acid in said effluent remains liquld. Since such fluid effluent is at a temperature of 175-235C (well above the temperature of benzoic acid solidification), and a gauge pressure of 6-25 kg/cm2, such product separation can be accomplished by decompression with attendant cooling of such effluent. Such decompression can be to ambient or subatmospheric pressure. The cooled effluent but ~20 still fluid effluent is pumped to said solid-liquid separation.
; Preferably such effluent is decompressed to subatmospheric pres-sure to avoid any flash evaporation in the means for solid-liquid separation.
The separated crystalline product can be washed with hot, fresh liquid benzoic acid and then with xylene, toluene or a combination thereof to remove adhering benzoid acid. The washed product is dried and the xylene or xylene-toluene mixture removed by drying is recovered for reuse. The xylene and/or toluene wash of product can be made in the means for solid-liquid separation but is preferably accomplished by suspending the benzoic acid washed solid product in the aromatic hydrocarbon.
.
-`` 107~3Z~ ~
The foregoing separating and washing of iso- or terephthalic ;
acid product provide the benefits of higher product purity because the product is recovered at a higher temperature than would be possible when acetic acid was the solvent. Such higher temperature separation leaves more of the impurity oxida-tion intermediates in the mother liquor. Further impurity re-moval is enhanced by the xylene and/or toluene washing because such aromatic hydrocarbons are better solvents for the impurities than is acetic acid.
Additional benefits resulting, in general, from the pre-sent inventive process are reduced combustion of the organic component of the solvent system; cleaner vent streams; less potential corrosion in the oxidation reactor, transfer lines and product recovery apparatus; and lower cost of oxidation reactor -because of lower reaction pressure.
With respect to combustion of benzoic acid component of the solvent system, this is reduced to 50 percent of that exper-ienced with acetic acid solvent for the same weight ratios of solvent to xylene and same operating temperatures. Moreover, the benzoic acid combustion products are only water and oxides ~
of carbon thus eliminating venting of the ester (methylacetate) -or separating it from solvent for recycle use as is needed when acetic acid is used as reaction solvent. Also, no appreciable amount of solvent vapor is vented with non-condensibles as is the case when acetic acid is the reaction solvent. This leads in the practice of the present inventive process to cleaner discarded gases.
Aerated, wet (3-15~ water) benzoic acid is substantially less corrosive at operating temperatures even when containing thebromine component of catalysis than aerated, wet (5-10% water) acetic acid containing such bromine component. Such substantially . ~ .~ . . : ,, :
1079Z~6 less corrosivity associated with the benzoic acid-water solvent permits the use of less expensive stainless steels of the SS316 type for process apparatus, especially the condenser, rather than the rather expensive metals such as titanium used when acetic acid is the solvent.
Capital investment and operating cost for the commercial practice of the present invention would be lower than when acetic acid or anhydrous benzoic acid are used as reaction solvents. Such lower costs result directly from the use of less expensive metals for process apparatus, lower operating pres-sure in the oxidation reaction vessel and its auxiliary con-densers and condensate receiver, the elimination of exhaust gas scrubbing, and the elimination of the later process steps of crystallization (generally two or three stages when acetic acid is the solvent), and solvent fractionation to recover solvent for recycle to the oxidation. -~
i~ The present inventive process, unlike processes using acetic acid solvent, is not retarded rate-wise by the presence ! of more than 5 weight percent water in the solvent system but there is a reaction rate penalty about 20 weight percent water.
Specific Embodiments of the Inventive Process As mentioned before the conditions essential for the con-~ duct of the present inventive process are the combination of i operating pressure at 6 24, preferably 14-20, kg/cm2 gauge with .,: .
the solvent system of benzoic acid (85-97 wt%) and water (15-3 wt %) to achieve control of substantially constant operating temperature selected from the range of 175-235C inclusive. The illustrative examples will provide combinations of operating pressure and solvent compositions to obtain good control of substantially constant temperature (not more than + 5C) from the average operating temperature from which those skilled in this art can make a selection or devise other useful combinations.
;
.
1~7929~
Although the use of a stirred reaction zone is important with respect to good air dispersion in the liquid reaction mix-ture and heat removal therefrom, only the ordinary skili of stirring design is involved. For example, the ordinary design criteria of reactor and stirrer-blade geometry, agitation pat-tern and stirrer power to keep product cyrstals suspended in the solvent system need be taken into account to provide the neces-sary stirring. Those criteria can be readily calculated on the basis of published formulae or from empirical data readily ob-tainable by simple experiments with small scale apparatus.
The useful weight ratio of solvent system to m- or p-xylene is, as before stated, in the range of 2-10:1Ø The illustrative examples will provide a basis for the process design ;
engineer to either choose therefrom a ratio for specific pro-cess design purpose or select a different ratio to meet the particular design devised.
Heat of reaction can be removed as hereinafter illustrated by the addition of water to the reaction zone for evaporation therefrom. The evaporation of S kilograms of water per kilogram of xylene oxidized will remove the heat of reaction. Heat of ~ -reaction can also be removed by known means of internal indirect heat exchange with heat exchange fluid; for example, such fluid flowing through a tube coil in the reaction zone. Also heat of reaction can be removed by any one of the known external fluid loop heat exchangers wherein liquid reaction mixture flows from the oxidation zone to the external heat exchange loop for in-direct heat exchange, for example to exchange heat with water and generate steam, and the cooled reaction mixture is pumped back into the stirred reaction zone. Many other known useful means for removing heat of reaction can be used.
:' '.
'''". '' ~ .
1~79Z96 Not previously mentioned are the parameters of components of catalysis which are from 0.3 to 1.5 weight percent of total metal and 0.3 to 1.5 weight percent bromine, both calculated as the element, based on the xylene. Heat of reaction in the pre-ferred mode will be removed by evaporation of reactor solvent, which would be condensed by a three stage condenser. The H2O
of reactor would be removed from last stage of the condenser, other condensed liquid returned to reactor based on the xylene.
The suitable source of Mn, Co and Ce can be salts of such metals soluble in the benzoic acid-water solvent system.
Such salts include the carboxylates:acetates, proprionates, butyrates, naphthenates and benzoates; the complexes acetyl-acetonate and ethylenediamine tetraacetate as well as the bromides.
, .
The source of bromine can be elemental bromine; ionic forms of bromine including ammonium bromide; bromides of the transition metal components of catalysis, hydrogen bromide per se or as hydrobromic acid, sodium or potassium bromide or sodium ' or potassium bromates; and organic bromides including tetra-bromoethane, dibromoethylene, benzylbromide, and bromobenzene.
Such sources of bromine are known from United States Patent No '~1 2,833,816 and its commonly derived foreign counterpart patents Illustrative Examples of Invention Conduct The following thirteen examples illustrate the conduct of the present inventive process by semi-continuous oxidation wherein terephthalic acid (TA) is produced by air oxidation of p-xylene (PX). The oxidation apparatus is a cylindrical oxidation vessel having a stirrer to agitate its reaction zone which, from the amount of solvent system used and product suspended therein after all the p-xylene had been charged and aerated, comprises about 60 volume percent of the total volu~e of the vessel. The re-~ .
_ 1079Z~6 maining 40 volume percent provides disengagement of gases and vapors from the stirred fluid in the reaction zone. Said oxida- ;
tion vessel is also fitted with separate means for introducing air into the lower portion of the oxidation zone, p-xylene and water into the upper portion of the oxidation zone, discharging -fluid oxidation effluent from the bottom of said vessel, dis-charging the disengaged mixture of gases and vapors from the top of the vessel, and means for sealing the vessel for its operation -at pressures above ambient pressure. The top discharge means is connected to a reflux condenser for condensing benzoic acid for , its liquid reflux and uncondensed gases and vapors discharge to a side arm type condenser operated to condense water. The water vapor condenser is connected to a receiving vessel which collects water condensate and discharges uncondensed gases (a mixture of nitrogen, oxygen and oxides of carbon together with some water vapor) from the top through a pressure control valved vent line.
A water freeze-out trap is between said pressure control valve (adjustable) and apparatus for sampling and analyzing the gases to be vented. The p-xylene is fed to the oxidation zone by a ; 20 metering pumped from a pressurized feed tank. Provision is also made to charge water to the oxidation zone by means of a combina-' tion of pressurized feed tank (3.5 kg/cm2 gauge above oxidationzone pressure), metering needle valve and rotameter but an addi-.1 - . .. .
tional by-pass through a ball valve is also provided to add a large amount of water to the reaction zone to quench the reaction quickly in the event an otherwise uncontrollable sudden rise of reaction temperature might occur. Adjustable means is provided -`~ for heating or cooling the stirred liquid or fluid contents in the oxidation zone system initially charged to the reaction vessel and maintaining said solution at operating temperature up to initial introduction of p-xylene and air and, if need be, "
`-~ 1079Z9~
after introduction of p-xylene is complete. The reflux con-denser is heated by steam, 7 kg/cm2 gauge pressure maximum, introduced through an air-pressurized steam regulator, by regulation of the air pressure, the control of the steam pres-sure over the range of 0-7 kg/cm2 to the condenser, hence con-trol of its operating temperature is achieved. Said air pres-sure is controlled in turn in response to the temperature in the reaction zone. For such operation of the condenser tempera-ture in response to the oxidation zone temperature, the steam pressure is increased when reaction temperature decreases and steam pressure is decreased when reaction temperature increases.
The attendant increase in steam pressure reduces water content of the solvent system and decrease in steam pressure increases water content of the solvent system. In the illustrative examples provided hereafter the described means for controlling reaction temperature by control of reflux condenser temperature (steam feed pressure) was sufficiently precise that it did not become necessary to add water in large quenching amounts. How-ever, when the exit vapor flow rates were low and temperature control of vent gas was difficult, more precise control of tem-perature was more facile with the injection of small amounts of water.
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-" 1079Z96 The p-xylene oxidations of following Examples 9-14 are conducted in the same manner and in the same equipment as described with respect to Examples 1-8, except in Example 14 the reaction solvent is made up by combining 80 percent of benzoic acid mother liquor from Example 13 with water, fresh benzoic acid, and manganese acetate tetrahydrate. Hence, the accumulation of intermediate products 4-CBA and p-toluic acid and the increase in color of the recovered product.
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---" 1079296 0.5 to 2.5 weight parts of bromine for each part by weight total metal and the ratio of air to xylene fed to said zone provide an exhaust gas therefrom containing 3 to 10 volume percent oxygen. ~ -In one aspect such a process is described wherein p-xylene is oxidized with air and the transition metal component of catalysis is provided by manganese and cobalt in the Mn/Co -weight ratio of from 1:1 to 6:1 and the sum of Mn and Co metal weights are within the 0.5 to 1.5 weight percent of p-xylene.
In a preferred embodiment such a process is provided wherein ~
the solvent system consists essentially of 90% benzoic acid - -and 10% water, the weight ratio of the solvent system to p-xylene is 2 to 7:1, the components of catalyst are in the concentrations of 0.015 to 0.1% cobalt, 0.08 to 0.2% manganese and 0.02 to 0.3% bromine based on said solvent, the oxidation zone tempera- ~;
ture is from 205 to 226.5C, the oxidation zone gauge pressure ~ -is from 14-24.6 kg/cm2, and the oxygen content of the exhaust ~
;~ gas is from 6-10 volume percent. -In a further aspect such an invention is provided wherein p-xylene is oxidized with air, the solvent system consists essentially of 90% benzoic acid and 10% water, the weight ratio of solvent system to p-xylene is 3-5:1.0, and the transition metal component of catalysis is manganese and the ratio of bromine to manganese is from 0.8 to 1.5:1.0 and the manganese concentration is from 0.15 to 0.2 weight percent of solvent.
In a preferred embodiment the operating temperature fluctuation limited to not more than -~ 5C from a selected constant pressure by varying the rate of water condensate re-turned to the oxidation zone.
For such continuous oxidation the unique catalysis of a combination of one or more transition metal oxidation catalyst and a source of bromine is provided by dissolving suitable souces .. : ~ ,. ..,, ~, . . .
.. . . . . . . .. .
` 10792~6 of the components in the solvent system.
The present inventive continuous process is conducted in a stirred oxidation zone to provide efficient dispersion of air in and distribution of heat of reaction through the liquid phase in the oxidation zone.
The heat of reaction will cause vaporization of a little benzoic acid and mainly water from the oxidation zone. Little or no xylene is vaporized because it is oxidized to products which do not tend to be vaporized at the operating conditions.
Satisfactory temperature control is achieved for substantially constant operating conditions by regulating the water content of the liquid reflux (mainly water) to the oxidation zone after ;
~ the condensation of said vapors to remove heat of reaction.
; The water content of the liquid reflux, generally 90-95 weight percent, can be regulated by the operating temperature of the reflux condenser. Change in oxidation temperature from a selected constant operating temperature can be corrected by varying the rate of addition of water (since the condensate ; has only 5-10 weight ~ benzoic acid) returned to the oxidation~20 zone. For example, the rate of water return by way of the re-flux liquid is decreased or increased in response to a decrease or increase of oxidation zone temperature from the selected constant temperature. Means for such variation of water con- -tent of liquid reflux and rate of water return to the oxidation zone are hereafter described. Such means can keep the change of oxidation zone temperature within 5C above or below the selected constant temperature for the oxidation zone.
The variation of water rate of such returned liquid should not decrease the water content of the solvent system below 3 weight percent because at such condition the uncontrolled wide temperature fluctuation conditions again occur. The variation ,' _ g _ --'` 10792~6 of such returned liquid should not increase the water content of the solvent system above about 15 weight percent, e.g. to 18 weight percent, because such amount of water deactivates the system of catalysis partially or completely to make the oxida-tion rate commercially unattractive.
For the purposes of this invention the m- or p-xylene oxidation is carried out with a weight ratio of the benzoic acid-water solvent system to xylene in the range of 2:1 to 10 Also, the system of catalysis is suitably provided by a source of bromine in combination with one or more of manganese, cobalt, ~ ~
or cerium as transition metal oxidation catalyst. Also, it is ~ -preferred to use an amount of air which provides from 2 up to 10 volume percent oxygen in the exhaust gas (benzoic acid-free basis) to minimize the amount of partial oxidation products and color body impurities in the iso- or terephthalic acid product recovered.
Operation of the present inventive process is conducted on a continuous basis for the combination of 6-25 kg/cm2 gauge pressure and the particular benzoic acid-water solvent system to proyide for efficient control of substantially constant tem-perature in the oxidation zone in the operating temperature ~ ~ .
range of 175-235C.
The continuous operation of the present inventive process ;;
does not have relatively high xylene concentration at start-up; -i.e., initiation of oxidation, as will be understood from the start-up procedure for continuous operation. Said start-up differs from batchwise operation in that there is initially charged to the stirred oxidation zone the components of the -unique catalysis and solvent system. The resulting solution is stirred and heated to a temperature at which oxidation is initi-ated, e.g., 160-170C, but preferably to operating temperature .
~1 .
, --``` 1079Z~
of 175-235C. When such heating is only to oxidation initiation temperature, then m- or p-xylene is pumped into the stirred liquid in the oxidation zone and air is injected into said stirred liquid at about 1000-1500 N liters per kilogram of xylene until the oxidation zone temperature reaches the oper-ating temperature selected from 175-235C. Thereafter the xylene is pumped into the oxidation zone and air rate is in-creased to the range of from about 3800 to about 5900 N liters per kilogram of xylene to provide the 3-10 volume percent oxygen in the exhaust gas (benzoic acid and water-free basis). After the weight ratio of originally charged solvent system to the total xylene charged reaches the selected ratio in the range of 3-10:1.0, the solution of catalyst components in the benzoic acid-water solvent system is pumped in at a rate with respect to continued xylene pumping to preserve the selected solvent to xylene weight ratio as the injection of air is continued at said 3800-5900 N l/kg xylene providing such 3-10 volume percent oxygen in the exhaust gas. The time for such initiation to complete continuous feed operation is relatively short but does provide time to adjust the operation of the condenser to which the exhaust gas is conducted for removing heat of reaction and adjust the rate of water condensate returned with liquid condensate reflux to the stirred oxidation zone. Upon reaching the operating aerated liquid volume of the oxidation zone, the fluid oxidation reaction mixture is then withdrawn from the oxidation zone to supply feed to the separation of iso~
or terephthalic acid product from liquid benzoic acid-water sol-vent system. --Although such operation from initiation through complete continuous operation introducing reactants and solvent system solution of catalysis and withdrawing fluid reaction mixture ~79296 is not preferred, it does serve as a useful start-up procedure ;
to gain experience with the unique temperature sensitivity -with respect to water content of the solvent system having the most pronounced effect on successful control of operating temperature.~ - -After such experience is gained then the start-up of the present inventive process can be simplified by resorting to the preferred start-up conditions. For the preferred start-up, the solvent system solution of components of catalyst needed to -~
reach operating volume of the reactor is charged and stirred and heated to the selected operating temperature under the selected operating pressure. Thereafter the xylene is pumped ~-in and air is injected into the stirred solvent at continuous ;~
operating rates with the condenser reflux system operating in response to the temperature of the oxidation zone. Removal of fluid is started when the total xylene charged provides, with respect to initial solvent system charged, the selected weight ratio of solvent system to xylene.
The continuous operation of the present inventive process ' 20 can be conducted in an oxidation vessel having a stirrer, a Z reflux condenser operated at a temperature of about the melting -` point of benzoic acid (121.7C) to condense benzoic acid as a liquid for reflux to the stirred oxidation zone and a side arm- -type condenser operated to condense water vapor for removal of by-product water. A pressure control valvè can be used between said condensers or preferably after the water vapor condenser, for example at the exit therefrom. Uncondensed gases can be ~I discharged from said condensate collecting vessel through the pressure reducing valve. The reaction vessel should be fitted with temperature and pressure measuring devices and means for charging reactants, solvent solution of components of catalysis, - 10~;~9296 and withdrawing fluid oxidation effluent. With such combina-tion of apparatus elements control of water content of the benzoic acid-water solvent system can be readily monitored and control-led within the 3-15 weight percent water content on the basis of a water material balance. Only a metered amount of water condensate is discarded which is equivalent to the amount of by-product water produced and the remainder of the condensate is pumped back into the reaction zone to control the oxidatibn zone at constant pressure.
Product iso- or terephthalic acid, relatively insoluble -in the solvent system, can be separated from the fluid oxida-tion effluent by any solid-liquid separation means such as by ;
filtxation or centrifugation, at a temperature at which benzoic acid in said effluent remains liquld. Since such fluid effluent is at a temperature of 175-235C (well above the temperature of benzoic acid solidification), and a gauge pressure of 6-25 kg/cm2, such product separation can be accomplished by decompression with attendant cooling of such effluent. Such decompression can be to ambient or subatmospheric pressure. The cooled effluent but ~20 still fluid effluent is pumped to said solid-liquid separation.
; Preferably such effluent is decompressed to subatmospheric pres-sure to avoid any flash evaporation in the means for solid-liquid separation.
The separated crystalline product can be washed with hot, fresh liquid benzoic acid and then with xylene, toluene or a combination thereof to remove adhering benzoid acid. The washed product is dried and the xylene or xylene-toluene mixture removed by drying is recovered for reuse. The xylene and/or toluene wash of product can be made in the means for solid-liquid separation but is preferably accomplished by suspending the benzoic acid washed solid product in the aromatic hydrocarbon.
.
-`` 107~3Z~ ~
The foregoing separating and washing of iso- or terephthalic ;
acid product provide the benefits of higher product purity because the product is recovered at a higher temperature than would be possible when acetic acid was the solvent. Such higher temperature separation leaves more of the impurity oxida-tion intermediates in the mother liquor. Further impurity re-moval is enhanced by the xylene and/or toluene washing because such aromatic hydrocarbons are better solvents for the impurities than is acetic acid.
Additional benefits resulting, in general, from the pre-sent inventive process are reduced combustion of the organic component of the solvent system; cleaner vent streams; less potential corrosion in the oxidation reactor, transfer lines and product recovery apparatus; and lower cost of oxidation reactor -because of lower reaction pressure.
With respect to combustion of benzoic acid component of the solvent system, this is reduced to 50 percent of that exper-ienced with acetic acid solvent for the same weight ratios of solvent to xylene and same operating temperatures. Moreover, the benzoic acid combustion products are only water and oxides ~
of carbon thus eliminating venting of the ester (methylacetate) -or separating it from solvent for recycle use as is needed when acetic acid is used as reaction solvent. Also, no appreciable amount of solvent vapor is vented with non-condensibles as is the case when acetic acid is the reaction solvent. This leads in the practice of the present inventive process to cleaner discarded gases.
Aerated, wet (3-15~ water) benzoic acid is substantially less corrosive at operating temperatures even when containing thebromine component of catalysis than aerated, wet (5-10% water) acetic acid containing such bromine component. Such substantially . ~ .~ . . : ,, :
1079Z~6 less corrosivity associated with the benzoic acid-water solvent permits the use of less expensive stainless steels of the SS316 type for process apparatus, especially the condenser, rather than the rather expensive metals such as titanium used when acetic acid is the solvent.
Capital investment and operating cost for the commercial practice of the present invention would be lower than when acetic acid or anhydrous benzoic acid are used as reaction solvents. Such lower costs result directly from the use of less expensive metals for process apparatus, lower operating pres-sure in the oxidation reaction vessel and its auxiliary con-densers and condensate receiver, the elimination of exhaust gas scrubbing, and the elimination of the later process steps of crystallization (generally two or three stages when acetic acid is the solvent), and solvent fractionation to recover solvent for recycle to the oxidation. -~
i~ The present inventive process, unlike processes using acetic acid solvent, is not retarded rate-wise by the presence ! of more than 5 weight percent water in the solvent system but there is a reaction rate penalty about 20 weight percent water.
Specific Embodiments of the Inventive Process As mentioned before the conditions essential for the con-~ duct of the present inventive process are the combination of i operating pressure at 6 24, preferably 14-20, kg/cm2 gauge with .,: .
the solvent system of benzoic acid (85-97 wt%) and water (15-3 wt %) to achieve control of substantially constant operating temperature selected from the range of 175-235C inclusive. The illustrative examples will provide combinations of operating pressure and solvent compositions to obtain good control of substantially constant temperature (not more than + 5C) from the average operating temperature from which those skilled in this art can make a selection or devise other useful combinations.
;
.
1~7929~
Although the use of a stirred reaction zone is important with respect to good air dispersion in the liquid reaction mix-ture and heat removal therefrom, only the ordinary skili of stirring design is involved. For example, the ordinary design criteria of reactor and stirrer-blade geometry, agitation pat-tern and stirrer power to keep product cyrstals suspended in the solvent system need be taken into account to provide the neces-sary stirring. Those criteria can be readily calculated on the basis of published formulae or from empirical data readily ob-tainable by simple experiments with small scale apparatus.
The useful weight ratio of solvent system to m- or p-xylene is, as before stated, in the range of 2-10:1Ø The illustrative examples will provide a basis for the process design ;
engineer to either choose therefrom a ratio for specific pro-cess design purpose or select a different ratio to meet the particular design devised.
Heat of reaction can be removed as hereinafter illustrated by the addition of water to the reaction zone for evaporation therefrom. The evaporation of S kilograms of water per kilogram of xylene oxidized will remove the heat of reaction. Heat of ~ -reaction can also be removed by known means of internal indirect heat exchange with heat exchange fluid; for example, such fluid flowing through a tube coil in the reaction zone. Also heat of reaction can be removed by any one of the known external fluid loop heat exchangers wherein liquid reaction mixture flows from the oxidation zone to the external heat exchange loop for in-direct heat exchange, for example to exchange heat with water and generate steam, and the cooled reaction mixture is pumped back into the stirred reaction zone. Many other known useful means for removing heat of reaction can be used.
:' '.
'''". '' ~ .
1~79Z96 Not previously mentioned are the parameters of components of catalysis which are from 0.3 to 1.5 weight percent of total metal and 0.3 to 1.5 weight percent bromine, both calculated as the element, based on the xylene. Heat of reaction in the pre-ferred mode will be removed by evaporation of reactor solvent, which would be condensed by a three stage condenser. The H2O
of reactor would be removed from last stage of the condenser, other condensed liquid returned to reactor based on the xylene.
The suitable source of Mn, Co and Ce can be salts of such metals soluble in the benzoic acid-water solvent system.
Such salts include the carboxylates:acetates, proprionates, butyrates, naphthenates and benzoates; the complexes acetyl-acetonate and ethylenediamine tetraacetate as well as the bromides.
, .
The source of bromine can be elemental bromine; ionic forms of bromine including ammonium bromide; bromides of the transition metal components of catalysis, hydrogen bromide per se or as hydrobromic acid, sodium or potassium bromide or sodium ' or potassium bromates; and organic bromides including tetra-bromoethane, dibromoethylene, benzylbromide, and bromobenzene.
Such sources of bromine are known from United States Patent No '~1 2,833,816 and its commonly derived foreign counterpart patents Illustrative Examples of Invention Conduct The following thirteen examples illustrate the conduct of the present inventive process by semi-continuous oxidation wherein terephthalic acid (TA) is produced by air oxidation of p-xylene (PX). The oxidation apparatus is a cylindrical oxidation vessel having a stirrer to agitate its reaction zone which, from the amount of solvent system used and product suspended therein after all the p-xylene had been charged and aerated, comprises about 60 volume percent of the total volu~e of the vessel. The re-~ .
_ 1079Z~6 maining 40 volume percent provides disengagement of gases and vapors from the stirred fluid in the reaction zone. Said oxida- ;
tion vessel is also fitted with separate means for introducing air into the lower portion of the oxidation zone, p-xylene and water into the upper portion of the oxidation zone, discharging -fluid oxidation effluent from the bottom of said vessel, dis-charging the disengaged mixture of gases and vapors from the top of the vessel, and means for sealing the vessel for its operation -at pressures above ambient pressure. The top discharge means is connected to a reflux condenser for condensing benzoic acid for , its liquid reflux and uncondensed gases and vapors discharge to a side arm type condenser operated to condense water. The water vapor condenser is connected to a receiving vessel which collects water condensate and discharges uncondensed gases (a mixture of nitrogen, oxygen and oxides of carbon together with some water vapor) from the top through a pressure control valved vent line.
A water freeze-out trap is between said pressure control valve (adjustable) and apparatus for sampling and analyzing the gases to be vented. The p-xylene is fed to the oxidation zone by a ; 20 metering pumped from a pressurized feed tank. Provision is also made to charge water to the oxidation zone by means of a combina-' tion of pressurized feed tank (3.5 kg/cm2 gauge above oxidationzone pressure), metering needle valve and rotameter but an addi-.1 - . .. .
tional by-pass through a ball valve is also provided to add a large amount of water to the reaction zone to quench the reaction quickly in the event an otherwise uncontrollable sudden rise of reaction temperature might occur. Adjustable means is provided -`~ for heating or cooling the stirred liquid or fluid contents in the oxidation zone system initially charged to the reaction vessel and maintaining said solution at operating temperature up to initial introduction of p-xylene and air and, if need be, "
`-~ 1079Z9~
after introduction of p-xylene is complete. The reflux con-denser is heated by steam, 7 kg/cm2 gauge pressure maximum, introduced through an air-pressurized steam regulator, by regulation of the air pressure, the control of the steam pres-sure over the range of 0-7 kg/cm2 to the condenser, hence con-trol of its operating temperature is achieved. Said air pres-sure is controlled in turn in response to the temperature in the reaction zone. For such operation of the condenser tempera-ture in response to the oxidation zone temperature, the steam pressure is increased when reaction temperature decreases and steam pressure is decreased when reaction temperature increases.
The attendant increase in steam pressure reduces water content of the solvent system and decrease in steam pressure increases water content of the solvent system. In the illustrative examples provided hereafter the described means for controlling reaction temperature by control of reflux condenser temperature (steam feed pressure) was sufficiently precise that it did not become necessary to add water in large quenching amounts. How-ever, when the exit vapor flow rates were low and temperature control of vent gas was difficult, more precise control of tem-perature was more facile with the injection of small amounts of water.
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-" 1079Z96 The p-xylene oxidations of following Examples 9-14 are conducted in the same manner and in the same equipment as described with respect to Examples 1-8, except in Example 14 the reaction solvent is made up by combining 80 percent of benzoic acid mother liquor from Example 13 with water, fresh benzoic acid, and manganese acetate tetrahydrate. Hence, the accumulation of intermediate products 4-CBA and p-toluic acid and the increase in color of the recovered product.
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The following p-xylene oxidations illustrate contin-;
uous conduct of the present inventive oxidation process.
These continuous oxidations are conducted in the same type of apparatus elements as described for the oxidations of the preceding fourteen examples with the exception the apparatus elements are larger. This is reflected in the greater amounts of p-xylene fed per hour. The continuous oxidations are started in the same manner as the semi-continuous and operated with p-xylene pumping until the weight ratio of solvent (initially charged) to p-xylene is reached. Thereafter a solvent solution of the components of catalysis is also pumped i into the reaction zone at a rate to maintain such solvent/-!
xylene ratio and TRE is withdrawn at the rate to provide the residence (hold) time, shown in Table III.
~i .:
TABLE III
-~ p-XYLENE OXIDATION IN BENZOIC ACID-WATER SOLVENT
Example Comparative I and II 15 , . .
Materials and Conditions Xylene Pump Rate, g/hr. 1510 1420 1050 Solvent water, wt. ~ 15 8 12 Co on Solvent, wt. % 0 0 0.03 Mn on Solvent, wt. % 0.20 0.20 0.09 Br on Solvent, wt. % 0.30 0.30 0.18 Solvent/p-xylene, wt. ratio 3.0 3.0 4.0 Operating temp., C. 217 217-226 227 Operating gauge, pres., kg/cm2 22.1 15.5 25.0 2 in exhaust, vol. % 6.9 5.5 5.5 Residence time, min. 45 45 50 Mole Co2/mole xylene 0.29 0.72 0.79 Total reaction effluent:
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The following p-xylene oxidations illustrate contin-;
uous conduct of the present inventive oxidation process.
These continuous oxidations are conducted in the same type of apparatus elements as described for the oxidations of the preceding fourteen examples with the exception the apparatus elements are larger. This is reflected in the greater amounts of p-xylene fed per hour. The continuous oxidations are started in the same manner as the semi-continuous and operated with p-xylene pumping until the weight ratio of solvent (initially charged) to p-xylene is reached. Thereafter a solvent solution of the components of catalysis is also pumped i into the reaction zone at a rate to maintain such solvent/-!
xylene ratio and TRE is withdrawn at the rate to provide the residence (hold) time, shown in Table III.
~i .:
TABLE III
-~ p-XYLENE OXIDATION IN BENZOIC ACID-WATER SOLVENT
Example Comparative I and II 15 , . .
Materials and Conditions Xylene Pump Rate, g/hr. 1510 1420 1050 Solvent water, wt. ~ 15 8 12 Co on Solvent, wt. % 0 0 0.03 Mn on Solvent, wt. % 0.20 0.20 0.09 Br on Solvent, wt. % 0.30 0.30 0.18 Solvent/p-xylene, wt. ratio 3.0 3.0 4.0 Operating temp., C. 217 217-226 227 Operating gauge, pres., kg/cm2 22.1 15.5 25.0 2 in exhaust, vol. % 6.9 5.5 5.5 Residence time, min. 45 45 50 Mole Co2/mole xylene 0.29 0.72 0.79 Total reaction effluent:
4-CBA, ppm. 15800 7400 630 p-Toluic acid, wt. % 6.55 2.65 0.037 p-Xylene, wt. % 0.086 0.0005 ND
Terephthalic acid, wt. % 8.48 18.0 22.7 Terephthalic acid yield, Mol. % 48.8 79.3 93.8 Washed filter cake:
4-CBA, wt. % 1.49 0.71 0.053 :
,'' ::
- 23 _ ~
~, :
~ .
--`` 1079296 In the conduct of p-xylene oxidation according to Comparative Example I, by-product water was not removed. That is, the reflux condenser is operated at a temperature to return all water and benzoic acid condensate to the oxidation zone. ~ , This would permit the benzoic acid-water solvent system to in-crease in water concentration from 10% to 18~ by weight at steady state operation. Such 18% water content is above the 15 upper limit permitting an acceptable rate of oxidation. Also 225 grams of p-xylene is added to the initial charge of solvent system containing the components of catalysis and p-xylene pump-ing is delayed until the time (calculated) for conversion of the initially charged p-xylene by the introduction of air. Under these modified operating conditions, temperature in the stirred -oxidation zone could not be controlled at the planned 217C, but rather the oxidation zone temperature cycled considerably above and below said temperature. Also the production of oxides of carbon and oxygen content of exhaust gas fluctuated sub-stantially which indicates not only poor control of temperature of reaction but indicates conditions of too high and too low oxygen concentration in the oxidation zone even though the air input was constant. The sum of effects adverse to control of reactivity and constant temperature can cause build-up of aromatic co and by-products to concentrations which significantly reduce the desired rate of oxidation to TA.
For the oxidation of Comparative Example II, the temperature of the reflux condenser was increased to permit re-moval of by-product water in a gas-vapor mixture at a temperature of 121C and maintain a 10~ water concentration in the solvent system. sut p-xylene (908 grams) is again precharged. However, the temperature in the oxidation zone again cycles, a constant : . , .: . ~ - :
. . . . , : . : : ..
10'79296 temperature of 218C could not be maintained and the oxygen consumption, in general, is low. The oxidation zone tempera-ture reached a maximum of 226.5C and at this point th ~oxy-gen consumption increases sharply as indicated by an attendant 75~ drop in oxygen content of exhaust gas. Also there was an accumulation of p-xylene condensate in the cold traps preceding the exhaust gas sampling and analyzing apparatus. Thus a sub-stantial amount of p-xylene was vaporized as it entered the oxidation zone maintained at 14.06 kg/cm2 gauge pressure an~
did not oxidize. Close control of reaction temperature was not ' possible because the temperature of the reflux condenser could not be closely maintained.
For the conduct of Example 15, the temperature of ' operation of the reflux condenser is maintained by water heated with a regulatable flow of steam added to the hot water input t to the condenser. In this way, a close control of the reflux ¦ condenser's temperature in the range of 121 + 0.5C. is achieved.
With this close control of the temperature of operation of ;
ll the reflux condenser and by the use of the indicated reaction l 20 zone pressure, close control of reaction temperature at 226.5C
~T is accomplished, and oxygen consumption reached a good steady -state.
The preparation of similarly high yields of good --color quality and purity isophthalic acid in the 85-95% benzoic acid and 15-5% water system can be obtained by substituting m-xylene for p-xylene in the foregoing illustrative examples.
' -.
, '~'' .
.1 ....
Terephthalic acid, wt. % 8.48 18.0 22.7 Terephthalic acid yield, Mol. % 48.8 79.3 93.8 Washed filter cake:
4-CBA, wt. % 1.49 0.71 0.053 :
,'' ::
- 23 _ ~
~, :
~ .
--`` 1079296 In the conduct of p-xylene oxidation according to Comparative Example I, by-product water was not removed. That is, the reflux condenser is operated at a temperature to return all water and benzoic acid condensate to the oxidation zone. ~ , This would permit the benzoic acid-water solvent system to in-crease in water concentration from 10% to 18~ by weight at steady state operation. Such 18% water content is above the 15 upper limit permitting an acceptable rate of oxidation. Also 225 grams of p-xylene is added to the initial charge of solvent system containing the components of catalysis and p-xylene pump-ing is delayed until the time (calculated) for conversion of the initially charged p-xylene by the introduction of air. Under these modified operating conditions, temperature in the stirred -oxidation zone could not be controlled at the planned 217C, but rather the oxidation zone temperature cycled considerably above and below said temperature. Also the production of oxides of carbon and oxygen content of exhaust gas fluctuated sub-stantially which indicates not only poor control of temperature of reaction but indicates conditions of too high and too low oxygen concentration in the oxidation zone even though the air input was constant. The sum of effects adverse to control of reactivity and constant temperature can cause build-up of aromatic co and by-products to concentrations which significantly reduce the desired rate of oxidation to TA.
For the oxidation of Comparative Example II, the temperature of the reflux condenser was increased to permit re-moval of by-product water in a gas-vapor mixture at a temperature of 121C and maintain a 10~ water concentration in the solvent system. sut p-xylene (908 grams) is again precharged. However, the temperature in the oxidation zone again cycles, a constant : . , .: . ~ - :
. . . . , : . : : ..
10'79296 temperature of 218C could not be maintained and the oxygen consumption, in general, is low. The oxidation zone tempera-ture reached a maximum of 226.5C and at this point th ~oxy-gen consumption increases sharply as indicated by an attendant 75~ drop in oxygen content of exhaust gas. Also there was an accumulation of p-xylene condensate in the cold traps preceding the exhaust gas sampling and analyzing apparatus. Thus a sub-stantial amount of p-xylene was vaporized as it entered the oxidation zone maintained at 14.06 kg/cm2 gauge pressure an~
did not oxidize. Close control of reaction temperature was not ' possible because the temperature of the reflux condenser could not be closely maintained.
For the conduct of Example 15, the temperature of ' operation of the reflux condenser is maintained by water heated with a regulatable flow of steam added to the hot water input t to the condenser. In this way, a close control of the reflux ¦ condenser's temperature in the range of 121 + 0.5C. is achieved.
With this close control of the temperature of operation of ;
ll the reflux condenser and by the use of the indicated reaction l 20 zone pressure, close control of reaction temperature at 226.5C
~T is accomplished, and oxygen consumption reached a good steady -state.
The preparation of similarly high yields of good --color quality and purity isophthalic acid in the 85-95% benzoic acid and 15-5% water system can be obtained by substituting m-xylene for p-xylene in the foregoing illustrative examples.
' -.
, '~'' .
.1 ....
Claims (5)
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process of preparing iso- or terephthalic acid by the liquid phase oxidation of m- or p-xylene with air in an oxidation zone at an elevated temperature of up to 275°C in the presence of a monocarboxylic acid solution of catalysis compon-ents comprising a source of bromine and one or more transition metal oxidation catalyst maintained as a liquid at said tempera-ture by elevated oxidation zone pressure, characterized by con-ducting the air oxidation of m- or p-xylene in a semi-continuous or continuous manner in a stirred oxidation zone containing said catalysis wherein the transition metal component is manganese or a combination of manganese with one or both of cobalt and cerium in a solvent system consisting essentially of liquid benzoic acid and water and at an oxidation zone temperature maintained sub-stantially constant at a selected temperature within the temper-ature range of 175 to 235°C by maintaining (a) the solvent system components within the range of 85 to 97 weight percent benzoic acid and 15 to 3 weight percent water, (b) the oxidation zone gauge pressure within the range of 6 to 25 kg/cm2, and (c) the removal of by-product water as vapor by cooling the exhaust from the oxidation zone to condense benzoic acid from reflux thereto and varying the amount of water returned to limit fluctu-ation of oxidation zone temperature to + 5°C from the selected temperature wherein said oxidation zone the weight ratio of such solvent system to said xylene is in the range of 2 to 10:1.0, said components of catalysis in the solvent system are present in the amounts of 0.2 to 1.5 weight percent total metal and 0.2 to 1.5 weight percent bromine based on the xylene with a weight ratio of bromine to total metal in the range of 0.5 to 2.5 weight parts of bromine for each part by weight total metal and the ratio of air to xylene fed to said zone provide an ex-haust gas therefrom containing 3 to 10 volume percent oxygen.
2. The process of claim 1 wherein p-xylene is oxidized with air and the transition metal component of catalysis is provided by manganese and cobalt in the Mn/Co weight ratio of from 1:1 to 6:1 and the sum of Mn and Co metal weights are within the 0.5 to 1.5 weight percent of p-xylene.
3. The process of claim 2 wherein the solvent system consists essentially of 90% benzoic acid and 10% water, the weight ratio of the solvent system to p-xylene is 2 to 7:1, the components of catalyst are in the concentrations of 0.015 to 0.1% cobalt, 0.08 to 0.2% manganese and 0.02 to 0.3% bromine based on said solvent, the oxidation zone temperature is from 205 to 226.5°C, the oxidation zone gauge pressure is from 14-24.6 kg/cm2, and the oxygen content of the exhaust gas is from 6-10 volume percent.
4. The process of claim 1 wherein p-xylene is oxidized with air, the solvent consists essentially of 90% benzoic acid and 10% water, the weight ratio of solvent system to p-xylene is 3-5:1.0, and the transition metal component of catalysis is manganese and the ratio of bromine to manganese is from 0.8 to 1.5:1.0 and the manganese concentration is from 0.15 to 0.2 weight percent of solvent.
5. The process of claim 1 wherein the operating tem-perature fluctuation limited to not more than + 5°C from a selected constant pressure by varying the rate of water condensate returned to the oxidation zone.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US70835876A | 1976-07-26 | 1976-07-26 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1079296A true CA1079296A (en) | 1980-06-10 |
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ID=24845486
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA282,898A Expired CA1079296A (en) | 1976-07-26 | 1977-07-15 | Iso- or terephthalic preparation in a benzoic acid-water solvent system |
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| Country | Link |
|---|---|
| JP (1) | JPS5315334A (en) |
| AR (1) | AR211428Q (en) |
| AU (1) | AU510097B2 (en) |
| BE (1) | BE857068A (en) |
| BR (1) | BR7704878A (en) |
| CA (1) | CA1079296A (en) |
| CS (1) | CS197297B2 (en) |
| DD (1) | DD132428A5 (en) |
| DE (1) | DE2732149A1 (en) |
| DK (1) | DK334777A (en) |
| ES (1) | ES461021A1 (en) |
| FR (1) | FR2359809A1 (en) |
| GB (1) | GB1577544A (en) |
| IE (1) | IE45504B1 (en) |
| IT (1) | IT1079740B (en) |
| LU (1) | LU77836A1 (en) |
| MX (1) | MX145448A (en) |
| NL (1) | NL7707202A (en) |
| PL (1) | PL199858A1 (en) |
| SU (1) | SU793378A3 (en) |
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| JP2893860B2 (en) * | 1990-05-17 | 1999-05-24 | 三菱瓦斯化学株式会社 | Production method of high purity isophthalic acid |
| GB9210832D0 (en) * | 1992-05-21 | 1992-07-08 | Ici Plc | Bromine catalysed oxidation process |
| DE59310066D1 (en) * | 1992-11-04 | 2000-08-03 | Clariant Gmbh | Process for the preparation of fluorinated benziles |
| ES2104512B1 (en) * | 1995-09-21 | 1998-07-01 | Interquisa | INDUSTRIAL PROCEDURE FOR THE MANUFACTURE OF AROMATIC CARBOXYL ACIDS. |
| PL389529A1 (en) | 2009-11-10 | 2011-05-23 | Fabryka Maszyn FAMUR Spółka Akcyjna | Method for mounting the arm to the body of longwall coal miner |
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| NL6413067A (en) * | 1963-11-14 | 1965-05-17 |
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1977
- 1977-06-27 AU AU26500/77A patent/AU510097B2/en not_active Expired
- 1977-06-29 NL NL7707202A patent/NL7707202A/en not_active Application Discontinuation
- 1977-06-30 MX MX169677A patent/MX145448A/en unknown
- 1977-07-04 IT IT50113/77A patent/IT1079740B/en active
- 1977-07-15 CA CA282,898A patent/CA1079296A/en not_active Expired
- 1977-07-15 DE DE19772732149 patent/DE2732149A1/en not_active Ceased
- 1977-07-19 GB GB30269/77A patent/GB1577544A/en not_active Expired
- 1977-07-22 BE BE179575A patent/BE857068A/en not_active IP Right Cessation
- 1977-07-25 BR BR7704878A patent/BR7704878A/en unknown
- 1977-07-25 IE IE1543/77A patent/IE45504B1/en unknown
- 1977-07-25 LU LU77836A patent/LU77836A1/xx unknown
- 1977-07-25 DK DK334777A patent/DK334777A/en not_active Application Discontinuation
- 1977-07-25 DD DD7700200266A patent/DD132428A5/en unknown
- 1977-07-25 FR FR7722785A patent/FR2359809A1/en active Granted
- 1977-07-25 AR AR268551A patent/AR211428Q/en unknown
- 1977-07-26 PL PL19985877A patent/PL199858A1/en unknown
- 1977-07-26 SU SU772505759A patent/SU793378A3/en active
- 1977-07-26 ES ES461021A patent/ES461021A1/en not_active Expired
- 1977-07-26 JP JP8887877A patent/JPS5315334A/en active Pending
- 1977-07-26 CS CS774957A patent/CS197297B2/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| IE45504L (en) | 1978-01-26 |
| SU793378A3 (en) | 1980-12-30 |
| GB1577544A (en) | 1980-10-22 |
| JPS5315334A (en) | 1978-02-13 |
| LU77836A1 (en) | 1978-02-02 |
| CS197297B2 (en) | 1980-04-30 |
| MX145448A (en) | 1982-02-17 |
| AU510097B2 (en) | 1980-06-05 |
| BR7704878A (en) | 1979-07-03 |
| PL199858A1 (en) | 1979-01-02 |
| BE857068A (en) | 1978-01-23 |
| ES461021A1 (en) | 1978-05-16 |
| DK334777A (en) | 1978-01-27 |
| FR2359809A1 (en) | 1978-02-24 |
| AR211428Q (en) | 1977-12-15 |
| NL7707202A (en) | 1978-01-30 |
| AU2650077A (en) | 1979-01-04 |
| IT1079740B (en) | 1985-05-13 |
| IE45504B1 (en) | 1982-09-08 |
| DE2732149A1 (en) | 1978-02-02 |
| DD132428A5 (en) | 1978-09-27 |
| FR2359809B1 (en) | 1980-07-11 |
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