JP4283709B2 - Method for producing medium oil and dimethyl ether for slurry bed reaction system - Google Patents

Description

  The present invention relates to a slurry bed reaction system medium oil and a process for producing dimethyl ether. In the present specification, “medium oil” is, for example, a liquid used as a medium in a slurry bed reactor (sometimes referred to as a suspension bubble column reactor or a gas-liquid / solid mixing reactor). It means the liquid (including at least a substance that is liquid under reaction conditions) that can constitute a catalyst slurry that is a mixture of the solid catalyst used in the reactor and the liquid.

  Conventionally, dimethyl ether has been produced mainly by using methanol as a raw material and dehydration reaction of methanol, but in recent years, a production method for directly synthesizing dimethyl ether from a raw material gas containing carbon monoxide and hydrogen has been developed.

  In this method, for example, in the presence of a copper-based methanol synthesis catalyst and a methanol dehydration catalyst (methanol conversion catalyst) such as alumina, the following chemical reaction formulas (1) and (2) As the reaction proceeds, dimethyl ether synthesis is achieved. That is, methanol is produced from carbon monoxide and hydrogen by the methanol synthesis catalyst, and then the previously produced methanol is dehydrated and condensed by the methanol dehydration catalyst to produce dimethyl ether and water. The water produced here further reacts with carbon monoxide as shown in chemical reaction formula (3) to become carbon dioxide and hydrogen.

前記の合成反応は強い発熱反応であり、また使用される触媒は高温により失活する問題がある。

The synthesis reaction is a strongly exothermic reaction, and the catalyst used has a problem of deactivation due to high temperature.

  For this reason, dimethyl ether is synthesized by a slurry bed reaction method, which has advantages such as the ability to effectively remove a large amount of reaction heat and easier temperature control than a fixed bed reaction method that is relatively difficult to remove heat. Research has been attracting attention.

In this slurry bed reaction system, a catalyst slurry in which a catalyst is suspended in an appropriate medium oil is used. The medium oil used in such a slurry bed reaction system has (1) high stability, that is, inert to the reaction, does not change with time, does not undergo thermal polymerization, thermal decomposition, and does not undergo reductive decomposition. it, (2) CO, it is highly soluble in the raw material gas such as 2H _2, (3) the boiling point of high, and (4) the freezing point is low, performance is required such.

  A method for producing dimethyl ether using a slurry bed reactor is disclosed in, for example, Patent Document 1 which is an application by Air Products and Chemicals, Inc. In this production method, examples of the medium oil for forming the catalyst slurry in the reactor include paraffinic hydrocarbons or hydrocarbon mixtures. In the examples, a refined natural mineral oil called Witco 70 is used. Is used. In addition, Air Products and Chemicals, Inc. also reported on synthesis of dimethyl ether using a slurry bed in Non-Patent Document 1, and here, a medium oil refined from a natural mineral oil called Drakeol 10 is used.

  Also, Patent Document 2 by Sungyu Lee et al. Discloses a method of synthesizing a gasoline component via dimethyl ether using hydrogen and carbon monoxide as raw materials using a slurry bed reactor. Here, a medium oil derived from natural mineral oil called Witco 40, Witco 70, or Freezen 100 is used as the slurry medium oil. Similarly, in Non-Patent Document 2 and other papers by Sangry et al., The synthesis of slurry bed dimethyl ether is reported, and here, Witco 40 and Witco 70 are used as the medium oil.

In addition, according to the ring analysis result using the ndM method (ASTM D3238) which this inventor called said Witco 40, Witco 70, Freezene 100, and Drakeol 10 said, all are based. % C _P (percentage of paraffin carbons to total carbons) is below 70. In addition, according to the results of molecular structure analysis using NMR or the like, all of the aforementioned Witco 40, Witco 70, Freezee 100, and Drakeol 10 are carbon having a branch, that is, carbon having 3 or more carbon-carbon bonds. Account for more than 20% of the total carbon number.

  These conventionally known medium oils obtained by refining from natural mineral oil have a problem that the efficiency of dimethyl ether synthesis reaction decreases with time. For example, according to Non-Patent Document 1, in the synthesis of slurry bed dimethyl ether using Drakeol 10, the dimethyl ether production amount decreases with time, and the synthesis amount of dimethyl ether under the same conditions is about 500 hours. It was reduced to about half later. In the synthesis of slurry bed dimethyl ether using not only Drakeol 10 but also conventionally used medium oils such as Witco 70 or Freezen 100, it has been found that the reduction in dimethyl ether production with time is very large. Further, when these natural mineral oils are thermally decomposed at high temperatures, it is inevitable that carbon residues are generated. That is, when these natural mineral oils are used as the medium oil, the catalyst may be deactivated by the coking of the medium oil. In general, it is necessary for medium oil to ensure fluidity at an appropriate temperature from the viewpoint of handling properties.

In view of such a situation, the present inventors, as a medium oil used in the production of oxygen-containing organic compounds typified by dimethyl ether using a slurry bed reactor, are mainly composed of hydrocarbons and paraffin carbons. A medium oil characterized by occupying 70% or more of the carbon number was previously proposed in Patent Document 3. Typical examples of the medium oil include polybutene obtained by copolymerizing isobutene and n-butene as main components.
Japanese Patent Publication No. 07-057739 US Pat. No. 5,459,166 JP 2000-109437 A US DOE Report, DOE / PC / 89865-T6, September 1992 Sunggyu Lee, et al. , “A Single-Stage, Liquid-Phase Dimension Ether Synthesis Process from Syngas I. Dual Catalytic Activity and Process Feasibility and Tissue Sensitivity”. , 9 (6), 653-679 (1991)

  The medium oil such as polybutene shown in Patent Document 3 has a high thermal stability and a low freezing point as compared with a medium oil derived from natural mineral oil, and has a high reactivity in the synthesis of, for example, dimethyl ether as a medium oil. It was what brought about.

  However, it has been found that the medium oil shown in Patent Document 3 decomposes and scatters little by little over time.

  Accordingly, an object of the present invention is to provide a medium oil having a high boiling point, a low freezing point, excellent stability, and high reactivity in the synthesis of, for example, dimethyl ether as a medium oil.

  This invention which solves the said subject is a medium oil used as a medium in the synthesis reaction of a slurry bed reaction system, Comprising: As a main component, carbon number is 16-50, tertiary carbon number is 1-7, 4th. A hydrocarbon chain having a chain length of 0 or more, a branched chain bonded to the tertiary carbon having 1 to 16 carbon atoms, and at least one tertiary carbon having a chain length of 4 or more in three directions It is a medium oil for a slurry bed reaction system characterized in that it contains a branched saturated aliphatic hydrocarbon that is bonded to the.

  In the medium oil for a slurry bed reaction system of the present invention, the branched saturated aliphatic hydrocarbon preferably has 20 to 40 carbon atoms and 1 to 4 tertiary carbons. In the present invention, the branched saturated aliphatic hydrocarbon is represented by the general formula (I):

（式中、Ｒ^１、Ｒ^２、Ｒ^４は、それぞれ独立に炭素数４〜１６のｎ−またはｉ−アルキル基、Ｒ^３は炭素数１〜３のｎ−またはｉ−アルキル基、ｍは１〜７の整数、ｎは０〜３７の整数、ｐは０〜１２の整数である。ただし［ ］の中の−（ＣＲ^２Ｈ）−、−（ＣＨ_２）−、−（ＣＲ^３Ｈ）−は、任意の順番で結合し、各単位の総数がそれぞれｍ、ｎ、ｐであるものとする。）で表されるものであるスラリー床反応方式用媒体油を示すものである。さらに、本発明は、前記分枝状飽和脂肪族炭化水素が、炭素数６〜１８のα-オレフィンの２〜８量体であるスラリー床反応方式用媒体油を示すものである。

(Wherein R ¹ , R ² and R ⁴ are each independently an n- or i-alkyl group having 4 to 16 carbon atoms, R ³ is an n- or i-alkyl group having 1 to ³ carbon atoms, m is An integer of 1 to 7, n is an integer of 0 to 37, and p is an integer of 0 to 12. However,-(CR ² H)-,-(CH ₂ )-,-(CR ³ H in [] )-Represents a medium oil for a slurry bed reaction system that is bonded in an arbitrary order and the total number of each unit is m, n, and p. Furthermore, this invention shows the medium oil for slurry bed reaction systems in which the said branched saturated aliphatic hydrocarbon is a 2-8 mer of a C6-C18 alpha olefin.

  Furthermore, in the medium oil for slurry bed reaction system of the present invention, the pour point of the medium oil medium oil for slurry bed reaction system is desirably −10 ° C. or lower.

  The present invention also shows a medium oil for a slurry bed reaction method in which the synthesis reaction of the slurry bed reaction method is one for synthesizing an oxygen-containing organic compound, particularly dimethyl ether, from a raw material gas containing carbon monoxide and hydrogen. Is.

  The present invention that solves the above-mentioned problems also includes (1) a medium oil of the above-described slurry bed reaction system medium oil, (2) a methanol synthesis catalyst, (3) a methanol dehydration catalyst and a shift catalyst, or a methanol dehydration / shift. A method for producing dimethyl ether, characterized in that a raw material gas containing carbon monoxide and hydrogen is circulated in a catalyst slurry containing a mixture with a catalyst.

  The present invention that solves the above problems further comprises (1) a medium oil of the above-described slurry bed reaction system medium oil, (2) a methanol synthesis catalyst, (3) a methanol dehydration catalyst and shift catalyst, or methanol dehydration / shift. A method for producing a mixture of dimethyl ether and methanol, characterized in that a raw material gas containing carbon monoxide and hydrogen is circulated in a catalyst slurry containing a mixture with a catalyst.

  According to the medium oil of the present invention, it is possible to improve the synthesis efficiency of oxygen-containing organic compounds such as dimethyl ether, to maintain high synthesis efficiency over a long period of time, and to decompose, volatilize, etc. over time. It can be used stably for a long period of time. This is extremely advantageous in the production of oxygen-containing organic compounds such as dimethyl ether, which require high production efficiency.

  Hereinafter, the present invention will be described in detail based on embodiments.

  The slurry bed reaction system medium oil according to the present invention has 16 to 50 carbon atoms, 1 to 7 carbon atoms, 1 to 7 carbon atoms, 0 to quaternary carbon atoms, and a component bonded to tertiary carbon. A branched saturated aliphatic group having 1 to 16 carbon atoms in the branch chain and at least one tertiary carbon bonded to a hydrocarbon chain having a chain length of 4 or more in three directions It is characterized by containing hydrocarbons.

  In the present specification, the “main component” means that 70% by weight or more, preferably 90% by weight or more is contained in the medium oil.

  In the medium oil of the present invention, the branched saturated aliphatic hydrocarbon as a main component has a carbon number of 16 to 50. When the carbon number is less than 16, for example, the boiling point is This is because the desired properties cannot be obtained due to the decrease, and on the other hand, if the carbon number exceeds 50, for example, the raw material gas solubility may not be sufficient. Although it depends on the molecular structure of the hydrocarbon, the branched saturated aliphatic hydrocarbon preferably has 20 to 40 carbon atoms, particularly preferably 30 to 40 carbon atoms.

  Also, the tertiary carbon number is set to 1 to 7. If the tertiary carbon number is 0, the total carbon number is 16 to 50 and the freezing point rises to become a solid at room temperature. On the other hand, if the number of tertiary carbons exceeds 7, the stability of the molecule will decrease, and decomposition and polymerization will easily occur, and if the number of branches increases, the viscosity of the liquid will increase. Because. Increasing the viscosity of the liquid is not preferable because, in addition to increasing resistance during feeding, the diameter of bubbles dispersed in the slurry bed reactor is enlarged, gas hold-up is lowered, and reactivity is lowered. . The tertiary carbon number is more preferably 1 to 4, particularly preferably 1 to 3.

  The medium oil of the present invention does not have quaternary carbon. If it has quaternary carbon, it can be used over time like medium oil such as polybutene shown in Patent Document 3. This is because thermal decomposition occurs, causing a problem in terms of stability. The quaternary carbon is more susceptible to dissociation of intramolecular bonds than the tertiary carbon, and it is desirable that the necessary branching is constituted by the tertiary carbon.

  In the medium oil of the present invention, the branched chain bonded to the tertiary carbon has 1 to 16 carbon atoms because when the carbon number exceeds 16, the carbon number exceeds 50. Here, the longest carbon column in one molecule is a main chain, and the branch is a carbon column separated from the main chain.

  Furthermore, in the medium oil of the present invention, at least one tertiary carbon is bonded to a hydrocarbon chain having a chain length of 4 or more in three directions. This is because, by having the structure, it is possible to realize the temperature range that can exist in the liquid between the pour point and the boiling point with the minimum branching. Since dissociation of intramolecular bonds is likely to occur at this branch, it is desirable to minimize branching. More preferably, it is bonded to a hydrocarbon chain having a chain length of 8 or more in 3 directions.

  Such a branched saturated aliphatic hydrocarbon in the medium oil of the present invention is not particularly limited, but includes, for example, a compound represented by the following general formula (I).

（式中、Ｒ^１、Ｒ^２、Ｒ^４は、それぞれ独立に炭素数４〜１６のｎ−またはｉ−アルキル基、Ｒ^３は炭素数１〜３のｎ−またはｉ−アルキル基、ｍは１〜７の整数、ｎは０〜３７の整数、ｐは０〜１２の整数である。ただし［ ］の中の−（ＣＲ^２Ｈ）−、−（ＣＨ_２）−、−（ＣＲ^３Ｈ）−は、任意の順番で結合し、各単位の総数がそれぞれｍ、ｎ、ｐであるものとする。）
一般式（Ｉ）におけるＲ^１、Ｒ^２、Ｒ^４として、具体的には、例えば、ｎ−ヘキシル基、ｎ−ペンチル基、エチルヘキシル基、ｎ−オクチル基、ｎ−ノニル基、ｎ−デシル基などが含まれるが、これに限定されるわけではない。

(Wherein R ¹ , R ² and R ⁴ are each independently an n- or i-alkyl group having 4 to 16 carbon atoms, R ³ is an n- or i-alkyl group having 1 to ³ carbon atoms, m is An integer of 1 to 7, n is an integer of 0 to 37, and p is an integer of 0 to 12. However,-(CR ² H)-,-(CH ₂ )-,-(CR ³ H in [] )-Are combined in an arbitrary order, and the total number of each unit is assumed to be m, n, and p, respectively.)
Specific examples of R ¹ , R ² and R ⁴ in the general formula (I) include an n-hexyl group, an n-pentyl group, an ethylhexyl group, an n-octyl group, an n-nonyl group, and an n-decyl group. However, it is not limited to this.

Specific examples of R ³ in the general formula (I) include a methyl group, an ethyl group, an n-propyl group, and an isopropyl group.

  The medium oil of the present invention contains a conventionally known medium oil (for example, the medium oil described in the above-mentioned prior art column) as a minor component in addition to the branched saturated aliphatic hydrocarbon which is the main component. can do. Furthermore, the medium oil of the present invention can contain, for example, hydrocarbons containing oxygen, nitrogen, silicon, and halogen as impurities, in addition to the main component and the small component. In addition, two or more different types of branched saturated aliphatic hydrocarbons that are the main components can be used in combination.

  The medium oil of the present invention may be synthetic or natural oil origin, but synthetic materials are preferred.

  In order to prepare the medium oil of the present invention having the characteristics as described above, for example, a method of separating paraffin from natural oil using adsorption on a molecular sieve, distillation from natural oil, or distillation and solvent extraction A method in which natural oils are separated by hydrogenation, a method in which natural oil is obtained by hydrogenation, a method in which product selectivity (paraffin selectivity) is synthesized, such as Fischer-Tropsch synthesis, or α-olefin is polymerized or copolymerized. The method can be used.

  The method for polymerizing or copolymerizing the α-olefin is not particularly limited, but is preferably a 2 to 8 mer of an α-olefin having 6 to 18 carbon atoms, more preferably 1-octene, 1-decene, It is desirable to obtain a dimer to pentamer of an α-olefin having 8 to 12 carbon atoms such as 1-dodecene. As one of the most preferable examples, for example, poly-1-decene (trimer) can be shown.

  To polymerize or copolymerize α-olefin, for example, aluminum trichloride, boron trifluoride or boron trifluoride and water, alcohol such as ethanol, propanol or butanol, carboxylic acid, ethyl acetate or ethyl propionate, etc. In the presence of a polymerization catalyst such as a Freedil-Crafts catalyst containing a complex with an ester of

  Fischer-Tropsch synthesis is a method of synthesizing liquid hydrocarbons by reaction of carbon monoxide and hydrogen using a catalyst (for example, an iron-based, cobalt-based or nickel-based catalyst, or ruthenium catalyst).

  The branched saturated aliphatic hydrocarbon that satisfies the above-described conditions according to the present invention does not desorb, decompose, or polymerize hydrogen even at a high temperature of about 300 ° C. Therefore, unlike the case where a conventionally known natural mineral oil is used as a medium oil, it does not thermally decompose at a high temperature to leave a carbon residue, and the possibility that the catalyst is deactivated by coking is extremely low.

In the medium oil of the present invention, the saturated aliphatic contained in the medium oil with respect to the total carbon number of the medium oil (that is, the sum of the carbon number of the hydrocarbon as the main component and the carbon number of other minor components). The percentage of hydrocarbon (% C _P ) is 70% or more, preferably 80% or more. If the% C _{P of the} medium oil is less than 70%, the synthesis efficiency of the oxygen-containing organic compound may not be maintained for a long time.

The ratio of the number of saturated aliphatic hydrocarbons contained in the medium oil to the total carbon number of the medium oil is not limited to the following analysis method, but for example, the ndM method (ASTM D3238) is used. The ratio of saturated aliphatic hydrocarbons in this specification is a value determined by the ndM method. Here, the ring analysis refers to the assignment of carbon atoms of all the compounds constituting the oil (ie,% C) according to a formula prepared in advance from the value of the physicochemical properties of the oil (ie, oily composition or oily mixture). _A ,% C _N ,% C _R ,% C _P ). Here,% C _A is to the total number of carbon atoms of the analyte oil, is the percentage of aromatic carbon atoms contained in the analyte oil (i.e., the number of ring members of carbon atoms of the aromatic ring),% C _N is to the total number of carbon atoms of the analyte oil is a percentage of naphthenic carbon atoms contained in the analyte oil (i.e., the number of ring members of carbon atoms of the alicyclic ring),% C _R are analyzed % Of aromatic carbon and naphthene carbon contained in the analysis target oil with respect to the total carbon number of the oil, and% C _P is the paraffin carbon contained in the analysis target oil with respect to the total number of carbons of the analysis target oil. The percentage of the number (ie the number of member carbon atoms of the saturated aliphatic hydrocarbon chain). In the oil used in the present invention, most of the aliphatic hydrocarbons are paraffinic hydrocarbons and contain almost no unsaturated aliphatic hydrocarbons. Therefore,% C _A +% C _N +% C _P = 100 Or,% C _R +% C _P = 100.

The weight average molecular weight of the medium oil of the present invention is not particularly limited, but is preferably 200 to 800, more preferably 280 to 600, and most preferably 400 to 600. If the weight average molecular weight of the medium oil is less than 170, the amount of evaporation of the medium oil during the reaction becomes excessive, and it is necessary to increase the trap capacity of the evaporation medium oil provided downstream of the reactor and the capacity of the oil recycle pump, Plant cost increases. Moreover, it becomes difficult to control the amount of oil in the reactor, and temperature control may be difficult. When the weight average molecular weight of the medium oil exceeds 800, the viscosity of the oil increases and the solubility of CO and H ₂ decreases, so the reactivity of the synthesis reaction decreases. The weight average molecular weight of the medium oil of the present invention can be determined by, for example, a mass spectrometer or gel permeation chromatography.

The pour point of the medium oil of the present invention is not particularly limited, but is preferably −10 ° C. or lower, more preferably −20 ° C. or lower, and further preferably −30 ° C. or lower. If the pour point is higher than −10 ° C., it may solidify at a room temperature or a general winter temperature. Therefore, it is necessary to keep the pipes warm, and the plant cost increases, oil handling, etc. The work itself can be difficult. Moreover, the DME produced by DME synthesis reaction, when dissolving the by-produced CO _2, if it is effective to cool the product gas to -20 ° C. or less, the medium oil scattered in the condenser has reached Since there is a risk of clogging, it is desirable that the pour point of the medium oil is −20 ° C. or lower, more preferably −30 ° C. or lower. The pour point can be determined, for example, according to JIS K 2269, and the pour point in the present specification is a value determined according to the above JIS K 2269.

  The viscosity of the medium oil of the present invention is not particularly limited, but is preferably 0.05 to 10 cP at the reaction temperature. If the viscosity of the medium oil is more than 10 cP, the moving speed of the raw material gas and the product dissolved in the liquid phase of the slurry bed reaction layer is decreased, and further, the gas hold-up and the total amount of bubbles are increased by increasing the bubble diameter. The surface area may decrease and the reaction rate may decrease. An exothermic reaction such as DME synthesis reaction requires heat removal from the reactor, so a heat exchanger is installed in the reactor. However, as the viscosity of the medium oil increases, the heat transfer coefficient decreases and the heat transfer Increase in area is required. On the other hand, if the viscosity of the medium oil is less than 0.05 cP, the catalyst is likely to settle and the dispersion of the catalyst is deteriorated, so that the degree of contact between the catalyst and the raw material gas is reduced and the reaction rate is lowered. There are things to do. The viscosity can be obtained, for example, by calculating kinematic viscosity and specific gravity, and calculating from these, and the viscosity in the present specification was determined by the method described above.

  The sulfur content in the medium oil according to the present invention is preferably several ppm or less, and more preferably 1 ppm or less. If the sulfur content in the medium oil is higher than the above range, sulfur may poison the catalyst and reduce the activity of the catalyst.

  The 50% distillation point of the medium oil according to the present invention (that is, the temperature at which 50% of the oil evaporates under normal pressure) is preferably 230 ° C. or higher. If the 50% distillation point is low and the amount of evaporation of the medium oil is large under the reaction temperature and pressure conditions, it is necessary to increase the capacity of the trap of the evaporation medium oil provided downstream of the reactor, which may increase the plan cost. Alternatively, it may be difficult to control the amount of medium oil in the reactor, and it may be difficult to control the reaction.

  Other physical properties of the medium oil that affect the reaction can include the solubility or dissolution rate of the raw materials, products, and reaction intermediates. In other words, in the case of dimethyl ether synthesis, the solubility and dissolution rate of raw material gases such as carbon monoxide and hydrogen, reaction intermediates such as methanol and water, and products such as dimethyl ether and carbon dioxide in medium oil affect the reaction. It is mentioned as a physical property of medium oil. When the solubility or dissolution rate of the raw material gas in the medium oil is low, the efficiency of the raw material gas reaching the catalyst and converting it is reduced. Further, when the solubility of products such as dimethyl ether and carbon dioxide is high, the production reaction of dimethyl ether and carbon dioxide occurring on the catalyst is difficult to proceed. Moreover, it is desirable that water and methanol as reaction intermediates immediately reach the active site of the next catalyst and be converted immediately after they are formed. The medium oil of the present invention can satisfy such requirements regarding the solubility and dissolution rate.

  The medium oil of the present invention is a medium oil used in a slurry bed reaction system. In the present invention, the slurry bed reaction method is not particularly limited as long as it is a slurry bed reaction method in which the reaction is carried out in a catalyst slurry that is a mixture of a solid catalyst and a medium oil. A slurry bed reaction method in which another organic compound (hydrocarbon) or oxygen-containing organic compound is synthesized from a raw material gas containing (hydrocarbon), carbon monoxide, and hydrogen can be given.

  The medium oil of the present invention can be particularly suitably used in a slurry bed reaction method in which an oxygen-containing organic compound is synthesized from a raw material gas containing carbon monoxide and hydrogen. Examples of the oxygen-containing organic compound include ethers such as dimethyl ether, methyl tertiary butyl ether, ethyl tertiary butyl ether or tertiary amyl methyl ether, alcohols such as methanol and ethanol, carboxylic acids such as dimethyl carbonate, acetaldehyde, and acetic acid. Mention may be made of acids, or dimethoxymethane or dimethoxyethane. The medium oil of the present invention can be used for synthesizing hydrocarbons such as olefins such as propylene and ethylene and gasoline components in addition to oxygen-containing organic compounds. The synthesis includes not only the case of synthesizing hydrocarbons and oxygen-containing organic compounds as final products, but also the case of synthesizing hydrocarbons and oxygen-containing organic compounds as reaction intermediates.

  In the method for producing dimethyl ether according to the present invention, a conventionally known method for producing dimethyl ether can be applied as it is, except that the medium oil according to the present invention is used as the medium oil. That is, by circulating a raw material gas containing carbon monoxide and hydrogen in a catalyst slurry layer composed of a mixture of a medium oil according to the present invention, a methanol synthesis catalyst, a methanol dehydration catalyst or a methanol dehydration / shift catalyst, Dimethyl ether can be produced. Of course, the present invention can also be applied to the case of using a catalyst having three functions of methanol synthesis, methanol dehydration, and shift. The raw material gas can be supplied by, for example, coal gasification or methane reforming, and the reaction temperature is preferably 150 ° C to 400 ° C, more preferably 250 ° C to 300 ° C. Moreover, 1-15 MPa is preferable and, as for the reaction pressure, 3-7 MPa is more preferable. The amount of catalyst present in the medium oil is preferably 1 to 50% by weight, more preferably 10 to 30% by weight, based on the medium oil.

  In the method for producing dimethyl ether according to the present invention, the methanol synthesis catalyst may be a known methanol synthesis catalyst, for example, a composition formula: Cu-Zn-MO (where M is aluminum, silicon, titanium, zirconium, chromium, cerium, and gallium). A catalyst represented by one or more metal atoms selected from the group consisting of:

  In the method for producing dimethyl ether according to the present invention, as the methanol dehydration catalyst, a known methanol dehydration catalyst, for example, a methanol dehydration catalyst mainly composed of alumina, or a dehydration catalyst mainly composed of silica, silica / alumina or zeolite is used. Can be used. In the method for producing dimethyl ether according to the present invention, copper, zinc, iron, chromium, or the like can be used as the shift catalyst.

  In the method for producing dimethyl ether according to the present invention, a methanol dehydration / shift catalyst may be used instead of the combination of the methanol dehydration catalyst and the shift catalyst. This methanol dehydration / shift catalyst is a catalyst having a methanol dehydration function and a shift function. For example, a catalyst in which a shift function is added to the methanol dehydration catalyst by copper (that is, a catalyst containing copper oxide and alumina). Methanol dehydration / shift catalyst (composition formula: Cu—Al—O)] as a main component, or methanol dehydration / shift catalyst (composition formula: Cu—Si—O) containing copper oxide and silicon oxide, or A methanol dehydration / shift catalyst (composition formula: Cu—Si—Al—O) containing copper oxide and silica / alumina can be used. The product obtained by the method of the present invention can be separated and purified by a conventional method.

  In the method for producing a mixture of dimethyl ether and methanol according to the present invention, a conventionally known method for producing a mixture of dimethyl ether and methanol can be applied as it is, except that the medium oil according to the present invention is used as the medium oil. That is, by circulating a raw material gas containing carbon monoxide and hydrogen in a catalyst slurry layer composed of a mixture of a medium oil according to the present invention, a methanol synthesis catalyst, a methanol dehydration catalyst or a methanol dehydration / shift catalyst, Mixtures of dimethyl ether and methanol can be produced. Of course, the present invention can also be applied to the case of using a catalyst having three functions of methanol synthesis, methanol dehydration, and shift. As the raw material gas, methanol synthesis catalyst, methanol dehydration catalyst, and methanol dehydration / shift catalyst used in the production of the mixture, the same compounds as those used in the dimethyl ether production method can be used. However, when producing a mixture of dimethyl ether and methanol, silica or silica / alumina-based methanol dehydration catalyst and shift catalyst, or methanol dehydration / shift catalyst containing silica as the main component or silica / alumina as the main component. It is preferable to use a methanol dehydration and shift catalyst.

  EXAMPLES Hereinafter, the present invention will be specifically described by way of examples, but these do not limit the scope of the present invention.

<< Purification of the Medium Oil of the Present Invention >>
1-decene was used as a raw material, polymerized at −20 to 30 ° C. with an aluminum chloride catalyst and water (cocatalyst), saturated with hydrogen, and purified. The physical properties were adjusted by the raw material composition, polymerization temperature and / or purification (fractionation) conditions.

Each chemical property of the obtained medium oil was measured by the following means. That is, the weight average molecular weight of the medium oil is determined by mass spectrometry and gel permeation chromatography; the vapor pressure is determined by the boiling point method using an everimeter; the percentage of the number of paraffin carbons relative to the total number of carbon atoms of the medium oil (% C _P ) was measured by the ndM method (ASTM D3238); the viscosity at 260 ° C. was measured by kinematic viscosity and specific gravity; and the pour point was measured by JIS K2269. As a result, all of the α-olefin oligomers obtained had the structural formula represented by the general formula (I), the weight average molecular weight was 427, the vapor pressure at 260 ° C. was 1.2 kPa, The pour point was −70 ° C., and all the physical properties of the percentage of paraffin carbon number (% C _P ), viscosity and pour point were within the expected range described above. Moreover, the sulfur content in the obtained medium oil was 1 ppm or less.

  Hereinafter, this medium oil is referred to as a medium oil of Example 1.

Comparative Examples 1 and 2

<< Purification of Medium Oil as Comparative Example >>
A mixture of n-butene and isobutene (including some butane) is used as a raw material, polymerized at −20 to 30 ° C. with an aluminum chloride catalyst and water (cocatalyst), saturated with hydrogen, and purified. did. The physical properties were adjusted according to the raw material composition, polymerization temperature and / or purification (fractionation) conditions, and a medium oil having a weight average molecular weight of 300 and a medium oil having a weight of 470 were fractionated. The chemical properties of these two types of medium oil were measured in the same manner as in Example 1. The vapor pressure at 260 ° C. of the medium oil having a weight average molecular weight of 300 is 27 kPa, the pour point is −40 ° C., the vapor pressure at 260 ° C. of the medium oil having a weight average molecular weight of 470 is 2.0 kPa, and the pour point is It was −20 ° C.

  Hereinafter, a medium oil having a weight average molecular weight of 300 is referred to as a medium oil of Comparative Example 1, and a medium oil having a weight average molecular weight of 470 is referred to as a medium oil of Comparative Example 2.

<< Synthesis of dimethyl ether / methanol and evaluation of synthesis efficiency >>
FIG. 1 is a configuration diagram for explaining a synthesis apparatus for synthesizing dimethyl ether.

Put the medium oil 1552g of Example 1 in a reactor of the synthesis apparatus shown in FIG. 1, followed by copper - zinc - alumina methanol synthesis catalyst _{(CuO / ZnO / Al 2 O} 3: 31/16/53 259 g and 129 g of methanol dehydration shift catalyst (CuO / SiO ₂ · Al ₂ O ₃ ) containing alumina as a main component [weight ratio of methanol synthesis catalyst to methanol dehydration shift catalyst (methanol synthesis catalyst: methanol dehydration catalyst) = 2: 1, total weight of methanol synthesis catalyst and methanol dehydration shift catalyst 388 g], after slurrying, the reactor was sealed. While stirring the slurry in the reactor, the raw material gas [carbon monoxide: 18.11 NL / min, hydrogen gas: 18.11 NL / min flow rate (measured by using a mass flow meter)] passed through the slurry. The synthesis reaction of dimethyl ether was carried out. The reaction temperature at this time was 260 ° C., and the reaction pressure was 5 MPa. Before carrying out the synthesis reaction of dimethyl ether, a 1: 1 mixed gas of H ₂ / CO was passed at about 220 ° C. for 12 hours in order to bring the catalyst into an appropriate reduction state. Thus, a preliminary reduction operation was performed.

In the synthesis reaction of dimethyl ether, the gas (product gas) that has passed through the reactor is cooled to about 30 ° C. by a heat exchanger, and a liquid mainly composed of methanol and water and unreacted in a gas-liquid separator. Separated into a gas containing gas components, carbon dioxide and dimethyl ether. The liquid recovered by the gas-liquid separator was extracted from the gas-liquid separator through a pressure reducing valve and brought to normal pressure, and CO ₂ and DME were volatilized to obtain MeOH and H ₂ O as liquids. The gas generated during decompression (not shown in FIG. 1) was analyzed for composition by gas chromatograph after measuring the flow rate using a gas meter. The composition of the obtained liquid was analyzed with a gas chromatograph after measuring the weight of a certain recovery time. The gas separated by the gas-liquid separator was measured for the composition using a gas chromatograph after measuring the flow rate using a gas meter. The gas separated by the gas-liquid separator, the gas generated when the liquid was depressurized, and the liquid remaining after the depressurization were calculated and added, and this was used as the composition of the product gas. From these results, the carbon monoxide conversion rate (unit =%) and the dimethyl ether yield (unit = mol / g catalyst / hour) were determined by the following calculation formula.

Carbon monoxide conversion = 100 × (V _in −V _out ) / V _in where V _in represents the carbon monoxide flow rate _in the raw material gas, and V _out represents the carbon monoxide flow rate in the product gas. .

Dimethyl ether yield = W _DME / W _{cat In the} formula, W _DME represents the yield of dimethyl ether per hour, and W _cat represents the catalyst weight.

  (1) Carbon monoxide (CO) conversion rate (unit =%) after 100 hours from the start of the reaction (2) Carbon monoxide (CO) conversion rate (unit =%) after 300 hours from the start of the reaction ), (3) Reduction rate of dimethyl ether (DME) yield (unit =%), and (4) Amount of scattered medium oil (unit = g) after 300 hours from the start of the reaction. The “decrease rate of dimethyl ether yield” in the above (3) is “dimethyl ether yield (B) after 300 hours from the start of reaction” relative to “dimethyl ether yield (A) after 100 hours from the start of reaction” ”. Decrease ratio [= (A−B) / A].

Comparative Examples 3 and 4

  The procedure described in Example 2 was repeated except that the medium oil of Comparative Example 1 and Comparative Example 2 was used instead of the medium oil of Example 1.

<< Results of Example 2 and Comparative Examples 3 and 4 >>
Table 1 below shows the results (1) to (4) in Example 2 and Comparative Examples 3 and 4.

上記表１をみても明らかなように、本発明に係る実施例１の媒体油を使用すると、長期間にわたってジメチルエーテル合成効率を高い水準に維持することができるのみならず、比較例１に係る媒体油と比較して、長時間使用しても媒体油の減少がほとんどなく、長期間安定して合成を行うことができることが判明した。

As apparent from Table 1 above, when the medium oil of Example 1 according to the present invention is used, not only can the dimethyl ether synthesis efficiency be maintained at a high level over a long period of time, but also the medium according to Comparative Example 1 Compared to oil, it has been found that even when used for a long time, there is almost no decrease in medium oil, and the synthesis can be carried out stably for a long time.

  More specifically, in Comparative Example 3 (Medium oil of Comparative Example 1), a CO conversion rate comparable to that of the medium oil of Example 1 was obtained, and the DME yield reduction rate, that is, deterioration with time was also comparable. However, the scattering amount of the medium oil was 20 times or more. The molecular weight distribution of the medium oil scattered in Comparative Example 3 extends to the molecular weight range of the fraction separated by fractional distillation, and the GC-MS analysis result of this scattering medium oil suggests thermal decomposition at the quaternary carbon part. It was.

  In Comparative Example 4 (medium oil of Comparative Example 2), the amount of scattered medium oil was about the same as that of Example 1, but the CO conversion rate at the initial stage and after stabilization was low, and the DME yield rate was reduced. Was also big. This is presumed to be due to the high viscosity of the medium oil of Comparative Example 2 and low raw material gas solubility. The molecular weight distribution of the medium oil scattered in Comparative Example 2 also extends to the molecular weight range of the fraction separated by fractional distillation, and the GC-MS analysis result of this scattering medium oil suggests thermal decomposition at the quaternary carbon part. It was.

  From the mass spectrometry, the medium oil of Example 1 was mainly composed of a trimer and a tetramer, and contained a trace amount of a dimer, a pentamer and a hexamer. The flying medium oil was mainly composed of a trimer and contained a trace amount of a dimer and a tetramer, but no pyrolysis product was contained.

  Note that, in both Example 2 and Comparative Examples 3 and 4, the amount of scattering of the medium oil is smaller than the amount of scattering calculated from the vapor pressure at 260 ° C. This is because the temperature at the top of the reactor is controlled to about 110 ° C., and only the medium oil that has passed through the gas or mist flows out. As for the medium oil scattered from the reactor, it is usual to collect only the medium oil and return it to the reactor with a high-pressure pump to keep the catalyst concentration constant. However, in Example 2 and Comparative Example 4, since the amount of scattering of the medium oil was small, it was not carried out, and in Comparative Example 3, it was expected that the amount of scattering increased due to the circulation of the lightened medium oil. A fresh medium oil of the same composition was replenished.

It is a block diagram for demonstrating the synthesizing | combining apparatus for synthesize | combining a dimethyl ether.

Claims (9)

  A medium oil used as a medium in a synthesis reaction of a slurry bed reaction system, having 16 to 50 carbon atoms, 1 to 7 tertiary carbon atoms, 0 to quaternary carbon atoms, and tertiary as main components The number of carbons of the branched chain bonded to carbon is 1 to 16, and at least one tertiary carbon is bonded to a hydrocarbon chain having a chain length of 4 or more in three directions. A medium oil for a slurry bed reaction system characterized by containing a branched saturated aliphatic hydrocarbon.   The medium oil for a slurry bed reaction system according to claim 1, wherein the branched saturated aliphatic hydrocarbon has 20 to 40 carbon atoms and 1 to 4 tertiary carbons. The branched saturated aliphatic hydrocarbon has the general formula (I)

(Wherein R ¹ , R ² and R ⁴ are each independently an n- or i-alkyl group having 4 to 16 carbon atoms, R ³ is an n- or i-alkyl group having 1 to ³ carbon atoms, m is An integer of 1 to 7, n is an integer of 0 to 37, and p is an integer of 0 to 12. However,-(CR ² H)-,-(CH ₂ )-,-(CR ³ H in [] The slurry according to claim 1 or 2, characterized in that)-is bonded in an arbitrary order, and the total number of each unit is m, n, and p, respectively. Medium oil for floor reaction.   The medium oil for a slurry bed reaction system according to any one of claims 1 to 3, wherein the branched saturated aliphatic hydrocarbon is a 2 to 8 mer of an α-olefin having 6 to 18 carbon atoms.   The medium oil for a slurry bed reaction system according to any one of claims 1 to 4, wherein the pour point of the medium oil is -10 ° C or lower.   The slurry bed reaction system according to any one of claims 1 to 5, wherein the synthesis reaction of the slurry bed reaction system synthesizes an oxygen-containing organic compound from a raw material gas containing carbon monoxide and hydrogen. Medium oil.   The medium oil for a slurry bed reaction system according to claim 6, wherein the oxygen-containing organic compound is mainly dimethyl ether.   (1) A catalyst comprising a medium oil according to any one of claims 1 to 7, (2) a methanol synthesis catalyst, and (3) a methanol dehydration catalyst and shift catalyst, or a mixture of a methanol dehydration / shift catalyst. A method for producing dimethyl ether, characterized in that a raw material gas containing carbon monoxide and hydrogen is circulated in a slurry.   (1) A catalyst comprising a medium oil according to any one of claims 1 to 7, (2) a methanol synthesis catalyst, and (3) a methanol dehydration catalyst and shift catalyst, or a mixture of a methanol dehydration / shift catalyst. A method for producing a mixture of dimethyl ether and methanol, characterized in that a raw material gas containing carbon monoxide and hydrogen is circulated in a slurry.

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