DE2063174A1 - Process for the production of unsaturated hydrocarbons with the aid of a zirconium oxide catalyst - Google Patents

Description

DR. ING. F. WtTESTHOFF DIPL. ING. G. PtTLS DR.ETPECIDIANN

DR. ING. D. BEHRENS

PATEN TAN WILTE

8 MUNICH 9O

SILENCE HAS

mühohkk

TJEL. NH, 00 20 51

1-38,939

Description of the patent application

Haldor Frederik Axel Tops / e Prydenlundsvej, Vedbaek, Denmark

una

Fluor Corporation

2500 South Atlantic Boulevard, Los Angeles, California,

UNITED STATES.

concerning

Process for the production of unsaturated hydrocarbons with the help of a zirconium oxide catalyst

The present invention relates to a process for the production of unsaturated hydrocarbons by catalytic Steam puffs of saturated hydrocarbons

especially / and on suitable catalysts. It affects em Process for the production of ethylene and propylene by steaming saturated hydrocarbons in the presence a zirconia catalyst.

10982 (7/1874

Ethylene and propylene are commonly produced by thermal cracking of higher hydrocarbons such as light naphtha in the presence of steam. This method of steam cracking is normally carried out so that one-hydrocarbon vapor mixture passes through the empty Rohrg which are heated to a temperature above 800 ⁰ C in the cracking zone. When using light naphtha as the raw material process steam cracking -fi methane and hydrogen, 32 wt .- ^ ethylene, 5 wt .- ^ ethane, 18 wt .- ^ propylene, 5 wt .- $ butadiene arise 18 percent in a typical. , 4% by weight of butylene and 18% by weight of gasoline / fuel, each based on the starting material.

The high temperature and the strong heat flow in the cracking zone place high demands on the materials of the Reactor. In addition, there is the required relationship between space velocity, temperature distribution, pressure drop in the system and linear velocity is of relatively great importance and requires substantial preparatory work on a semi-industrial scale.

It is also known to produce unsaturated hydrocarbons by catalytic cracking of higher saturated hydrocarbons at temperatures of 500 to 700 ^° C. using silicon oxide-aluminum oxide catalysts. However, these processes become very cumbersome with carbon deposits on the catalyst which must be continually removed during the process.

It was recently described in French patent specification 1,127,494 that catalysts used for steam baking are suitable, should be able to split the C-C bonds of the hydrocarbon chains and the reaction between steam and carbon, and that they also have a low dehydrating activity

- 3 -10983 (7/1974

should. The latter property is important because too much dehydration activity leads to the formation of free carbon It has also been suggested that these desirable properties can be achieved by combining zirconia with one or a number of other oxides, such as the rare earth oxides, antimony oxide, and inactive oxides, the rich in magnesium oxide could be achieved. Other oxides, optionally in small amounts in the catalyst may contain are iron, aluminum? Copper ^ Calcium, barium; Silicon and titanium oxide. It is said there that a stable catalyst that does not lead to carbon deposition has a low porosity and a specific

Surface in the range of 0.02-1 m / g can be obtained by heating a mixture of zirconium oxide and other oxides to a temperature of at least 1300 ^° C. This treatment should lead to a solution of the oxides by solid diffusion.

However, there are problems related to the manufacture and use of zirconia analyzer. It is known to compress the oxide powder into beads of the desired size and shape and to achieve a suitable mechanical strength of the beads by heating at a temperature above 1000 C or even 1300 ⁰ G. However, pure zirconium oxide is subject to ^{a reversible allotropic transformation at approximately 1000 °} C., which leads to a considerable change in volume (approximately 9 ^). This change in volume has an adverse effect on the mechanical properties of the catalyst particles, and it is now necessary to convert the zirconium oxide into a stabilized form. This can be achieved by reacting with certain inactive oxides such as magnesium oxide. It is known that this reaction is accelerated by the presence of certain other oxides, such as rare earth oxides, for example lanthanum oxide.

- 4 -1098 ^ 7/1974

⁴ L --j o J ι 4

It is an object of the present invention, a method for producing unsaturated hydrocarbons such as ethylene and propylene, to develop by steam cracking of saturated hydrocarbons in the presence of a Zirkoncxid catalyst which has been esteilt by a method fro _a, dasdas heating to a temperature below 1000 ⁰ C, a significant deposition of carbon on the catalyst is still avoided.

It has now been shown that heating the catalyst to temperatures above 1000 C and simultaneous Reaction of a zirconium oxide with one or more inactive oxides is not necessary if at least one Part of the starting material from which the zirconium oxide catalyst has been produced from amorphous zirconium oxide and / or a zirconium compound which is converted into amorphous zirconium oxide when heated.

It has further been found that the resistance can be ge _e enüber of carbon deposition of such a zirconium oxide catalyst substantially improved by addition of an alkali metal compound to the catalyst. This accelerating effect of an alkali compound is known from other steam hydrocarbon reactions in the presence of a catalyst.

The present invention relates to a process for the production of unsaturated hydrocarbons such as ethylene and propylene by gas catalytic reaction using a feedstock consisting essentially of saturated hydrocarbons consists, at a temperature below 1100 C and a pressure of 0.1 to 50 atmospheres in the presence of additional steam is reacted with a zirconium oxide catalyst made from a raw material is, aas is at least partially amorphous zirconium oxide and / or a zirconium compound, which when heated in amorphous

ORIGINAL mS? BGTED " ⁵ " 1098 ^ 7/1974

Converts zirconium oxide, the sirconium oxide catalyst 0.1 to 10 5e; v.-fo of an alkali compound, calculated as oxide.

The invention also relates to a catalyst for manufacture of unsaturated hydrocarbons such as ethylene and propylene, from saturated hydrocarbons in the presence vcn steam produced from a starting material has been before. at least a part of the zirconium oxide and / or a circular connection that occurs when etching in amorphous zirconium oxide umv.ancelt, is this catalyst 0.1 to 10 wew .- ^ j, calculated as ^ xid, an .al.kaliveroir.dung contains.

Is a cevcrzu _fc th Ausführungsfcrm cies erfindungsgemci £ en procedure we α the reaction at a temperature in the range 200 to 90C VCN ⁰ O, preferably in the range of 500 ice 850 0 performed. Ls is also preferable to l ^; jerk iiu area :. from 1 to 15 atmospheres measured at the outlet of the reactor.

The feedstock can consist of a single saturated hydrocarbon or a mixture of saturated hydrocarbons, and it can contain a minor proportion of unsaturated hydrocarbons if necessary for the manufacture of the desired products. G-eeignete hydrocarbons include propane, butane, and liquid hydrocarbons such as light l ^ aphtiia and so _fc ar crudes. In the case of a process and catalyst according to the invention, the presence of sulfur does not interfere, which may even be desirable since it can protect the free metal surface of the reactor. The sulfur can originally be present in the starting material or it can be added in the form of the free element or in the form of compounds, such as organic carbonising compounds, sulphurous hydrogen and carbon dioxide.

τ »a / · ... · / · *. · BAOORIQiNAL - 6 10 93 ^ 7/197 ^

2 O G 3 1 7 A

So much steam should be exposed that "is" in the reactor a weight ratio of steam to hydrocarbon feedstock gives from 0.01 to 10. The ratio should preferably be as low as possible so Just a clear carbon deposit on the Catalyst is avoided, e.g. 0.1 to 1.0.

The method according to the invention can work at low temperatures and the low energy required results in a high thermal effectiveness. The requirements to be placed on the equipment are thereby reduced, which leads to lower costs and also to a lower vulnerability of the materials in the process. The shape / work requirements are less stringent, which leads to greater flexibility and safety compared to the thermal cracking process.

The catalyst is a zirconia catalyst that is made from a starting material, at least part of which is amorphous zirconium oxide or a zirconium compound, which turn into amorphous zirconium oxide when heated - "" - "" ' walks, is. The starting mixture is produced in powder form and then pressed into parts of the desired shape and size. The necessary strength is obtained during the heat treatment. The catalyst used in the present invention can

excellent Lüecnanische properties by a simple heat treatment below 1000 ⁰ C, preferably at a temperature in the range from 700 to 90O ⁰ C, obtained. In this way, the problems that occur due to the allotropic conversion of zirconium oxide at approximately 1000 ^° C. are avoided. This result was achieved by the presence of amorphous zirconia in the catalyst particles during the heat treatment.

If catalyst particles are made from crystalline zirconia only, they will not achieve equivalent

- 7 -109 8 ^ 7/1974

mechanical strength by heating to temperatures below 100O ⁰ C. This is because that the zirconia crystals do not begin to react with each other, as long as the temperature is not much higher than 1000 G. ⁰ "eixn jeuoch amorphous zirconium oxide is present, begins aie äeaktion at temperatures aie very much are at 100O ⁰ C. The amorphous zirconium oxide can either be contained in the powdery starting material from which the analyzer particles have been produced, or it can be formed during heating by converting a zirconium compound contained in the powdery starting material. Examples of zirconium compounds which are converted into amorphous zirconium oxide when heated are basic zirconium carbonate and zirconium hydroxide.

The molar ratio of amorphous zirconia to total zirconia is not very critical. The ratio can be as low as 10 µS, or all of the zirconia can be in the form of amorphous zirconia or a zirconium compound that converts to amorphous zirconia when heated. The proportion should preferably be at least * \ 5 %.

It is important that carbon does not build up on the zirconia catalyst during use in steam-cracking hydrocarbons. It is known that alkali metals accelerate the reaction between carbon and steam, and the presence of an alkali compound in the zirconia catalyst tends to reduce or avoid the deposition of carbon. It has been found that an amount of 0.1 to 10 wt -.% Alkali metal compound calculated as oxide, the deposition of carbon is effectively prevented, with the preferred range of 0.3 to 7 wt .- # alkali metal, calculated as oxide , amounts to. The alkali compound can be added in various ways. It can be added to the powdery starting material or it can be added to the catalyst after the heat treatment by impregnation

- 8 -1-Q9ei7 / 1974

can be added with a solution of an alkali compound. It can also be added to the catalyst in the form of an alkali metal vapor or a vapor of an alkali compound can be added. Examples of suitable alkali compounds are Nitrates, oxides and hydroxides. Potassium compounds are particularly suitable. . ·

The invention is illustrated by the following examples explained in more detail. .

Manufacture of the catalysts

The composition and the properties of the catalysts of Examples 1 to 6 are given in Table I. Examples 1, 2 and 3 show comparative catalysts and Examples 4, 5 and 6 show catalysts according to the invention. The exact preparation of the individual catalysts is described below.

Example 1 (comparison)

321 g of a wet filter cake of basic zirconium carbonate containing 46% by weight of zirconium, calculated as oxide, were suspended in 4.2 l of water together with 39 g of silicon dioxide and 169 g of magnesium oxide. 130 g of lanthanum nitrate, La (NO ,,), .6 HpO, were dissolved in the suspension. A slight excess of concentrated aqueous ammonia was then added to precipitate the hydroxide. The resulting suspension was filtered and washed. The filter cake was dried for 16 hours at 15O ⁰ C and 4 hours in a ball mill together with 4 percent by _e - milled loose fibers $ graphite, and 3 wt .- $> cellulose '. The resulting powder turned to. Compressed tablets with a height and a diameter of 9 mm and calcined ^{at 1TOp 0 C for 2 hours.}

Example 2 (comparison)

400 g of crystalline zirconium oxide were mixed with 17 g of graphite

109 8 ^ 7/1974

~ 9 -

and 13 g of cellulose fibers mixed and ground in a ball mill for 4 hours. The mixture was then compressed into tablets with a height and a diameter of 9 mm. The tablets were then fired at 85O ⁰ C. The burned tablets have almost no mechanical strength and disintegrated into a powder when handled, so that no experiment was carried out with this catalyst.

Example 3 (comparison)

870 g of a wet filter cake made of basic zirconium carbonate which contained 46% by weight, calculated as oxide, was ^{dried for 16 h at 150 °} C. The dried substance was mixed with 17 g of graphite and 13 g of cellulose fibers and for 4 h in one ball mill. Subsequently, the mixture was formed into tablets. the tablets were then calcined 2 hours at 850 ⁰ C. the resulting catalyst consisted of practically reinemZrO ₂ *

Example 4

A suspension was prepared from 320 g of ZrO ₂ in 5 1 of water at 65 ⁰ C. This was followed by 27ö Zr (NO ₃ ). · 5H ₂ O dissolved therein. 226.5 g of NH.HCO were added to this mixture. Precipitation took 15 minutes and the mixture was stirred for 1 hour and then filtered. The precipitate was washed well with water. This precipitate was for 16 hours at 12O ⁰ C and then dried for 1 hour at 400 ⁰ C. The dried precipitate was mixed with 17 g of graphite and 13 g of cellulose fibers and ground in a ball mill for 1 hour. The mixture was then shaped into tablets. The tablets were then heated ^{to 850 ° C. for 2 h.} 125 ml of these tablets were impregnated with a solution of 35 g of KNO ^ in 100 ml of water and then burned ^{at 400 ° C. for a further 2 hours.} The resulting catalyst contained 6 wt .-? O K,

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82? 7/1974

Example 5

This catalyst was prepared in accordance with catalyst 5 with the exception that the tablets during the 2 hours long burning "at 85O ⁰ C in the immediate vicinity ·:

en / a substance containing potassium oxide. In this way potassium was transferred to the catalyst via the vapor phase. The resulting catalyst contained 0.4% by weight r-fo potassium, calculated as the oxide.

Example 6

217 kg of an aqueous paste of basic zirconium carbonate containing 46% by weight of zirconium, calculated as oxide, was suspended in 500 l of water. 14.5 kg of potassium nitrate were dissolved in "the" suspension, which was then dried to a powder. The powder was mixed with 4 kg of graphite and 3 kg of cellulose fiber to form rings with an outer diameter of 1 mm and an inner diameter of 6 mm and pressed to a height of "10 mm. Those rings were finally calcined for 2 hours at 85O ^0-C. The resulting zirconium oxide catalyst. contained 6.7 wt% potassium calculated as oxide. \ Z

Investigation of the catalysts on a laboratory scale ""'

All catalysts, also prepared according to Example 2 ^ were examined in an electrically heated tubular reactor with an inner diameter of 25 mm. The catalyst. Tablets or rings were crushed and 125 ml of a sieve fraction of 5 to 4 mm was placed in the reactor. ;: _Arrival: .. closing a mixture of hydrocarbon and steam was introduced at a possible steam to Kohlenv / asserstpff weight ratio of 0.4. The steam-hydrocarbon mixture was first passed through a preheater and then ... through the reactor, the low velocity being 4 * 2 volumes of liquid to volume of catalyst. h was.

- 11 - "

TO 9 82 ^ y 197

The starting material went through the reactor from top to bottom. The temperature was at the upper end of the catalyst 59 ° ⁰ C, in the middle and at the lower end of the catalyst bed 75O ° C ... The light emerging from the reactor mixture water injected was quenched by TUs in the outlet of the reactor and the composition of the outgoing gaseous product was determined by gas chromatography. Two different hydrocarbon starting materials were used, one of which was a dense naphtha fraction with a composition by weight of 24.1 $ isopentane, 53.6 $ η-pentane, 13.5 $ isobexane, 5.65a η-hexane and 3 , 2 $ aromatics and the other was essentially pure n-heptane. The ethylene yield is generally higher when starting from heptane than when starting from naphtha. The yields of 2 different catalysts can therefore only be compared if the same hydrocarbon starting material is used. Further details of the experiments and their results are given in Table II.

The catalyst 2 (comparative catalyst) was prepared from crystalline zirconium oxide without adding amorphous zirconium oxide or a compound which converts to amorphous zirconium oxide when heated. This catalyst therefore did not receive any mechanical strength when heated to 850 ^° C. and no tests could be carried out with it.

The catalyst 1 (Comparative Catalyst) had a composition in which a stable catalyst should arise, which should be stable after heating at 1300 ⁰ C against Kohlenetoff deposition. In the present example, an attempt was made to see if heating to such a high temperature could be avoided by making the catalyst from basic zirconium carbonate. Although except calibrating strength was obtained at 1100 ⁰ C, he had no stability towards carbon deposition.

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109 6 ^ 7/197 4

The catalyst 3 (comparative catalyst) was according to of the invention, with the exception that no alkali was included in the catalyst mass. consequently the possessed Catalyst has a low resistance to eggs Carbon deposition.

The remaining catalysts 4 _S 5 and 6 in accordance with the present invention. They all have sufficient strength and their resistance to carbon deposition is satisfactory since virtually no carbon was found on the catalyst after it was used for several hundred hours.

Investigation of the catalysts on a semi-industrial scale

The catalyst 6 was also examined on a pilot-scale in a tubular reactor heated to a length of 6 m and an internal diameter of 30 mm. 40 liters of the catalyst 6 were added to the reactor. The reactor was heated with a series of oil burners. Into this reactor were 200 kg / h of a Faphtha fraction having a boiling range of 38-112 ⁰ C, less than 0.2 parts by volume of aromatic compounds and 1 to 2 Yoi, -fo naphthenes containing initiated. In addition, 120 kg / h of steam were introduced into the reactor, giving a steam to liaphtha weight ratio of 0.6. The inlet pressure was 10.9 ata and the outlet pressure was 1.5 ata. The temperature at the center was at the inlet of 510 ⁰ C, 75O ⁰ C and outlet 825 ⁰ C. The unit was operated under these conditions for 490 hours while an average yield, based on the Kohlenwasseretoff-Ausgangsmaterialjvon 29.5 wt .- ^ Cp ^ 4 ^J 18.9 wt .- # C K _{3 6,} 10.0 wt. ~? ö C ₄ e _8, 5.2 wt .- $ C ₄ H _6, 17.7 Gevi. CH ₄ , 6.8% by weight > C ₂ H ₆ , 2.5% by weight CO ₂ , 7.0% by weight of saturated hydrocarbons with a carbon number of more than 4 and 1.5% by weight H ₂ obtained. During the experiment there was no sign of carbon accumulation on the catalyst and after the experiment only 2 to 3% by weight were found on the catalyst, which is absolutely permissible. - 13 _

1098 ^ 7/1974

Tabel

Catalyst no,

Molar ratio of amorphous ZrO2 _{Q q} to total ZrO ₂ , f $) *

specific surface

7.5-4.5 1.3

Porosity, (vol. - $>) 36 - 39 32 * 40

Composition: 44 100 100 94 99.6 93.3 Wt .- $> ZrO ₀
C. O O O 6th 0.4 6.7 Wt .- $ K ₂ O 17th O O O O O Wt .-? £ SiO ₂ 2 O O O O O Weight fi Ia ₂ O, 36 O O O O O Gew · - fo MgO

1098 ^ 7/197 *

! Table II

Attempt 'No. A BOBE

Catalyst No. 1. -54 5 .6

Druek, (ata) · "2.0 1.5 1.3 1.3 1.3 Starting material heptane heptane naphtha heptane heptane Yield *: weight percent

Pawn of trial, (h)

Carbon; on ^ the Catalyst, (wt.

24.7 22 8th 12.0 25.7 24.2 5.9 10, 7th 9.2 10.8 11.5 40 40 230 € 00 232 50 -50 0.2 1.0 0.3

* Based on the hydrocarbon feedstock

Claims ' - 15 -

109 8 ^ 7/1974

Claims (1)

S R. ING. F. WUESTHOFF. 8 MUNICH9O DIPI ^ iNCG-PULS _1t - SCHWEIOEHSTHASSE S DR-Ev-PECHMAIfN ~ ° '- ^ "" T »« ro »asoeoi tj Γ \ C * O" 1 HL DR. ING. IJ. BEHRENS m.rontMMii> iix9 »r ^ ^ ⁴ ^ I / H PATENTANW-XI.TE. MowomiMt mcnchkh. TEL. KH. 66 20 51 1A-38959 Claims Process for the production of unsaturated hydrocarbons by catalytic gas reaction, in which a starting material which essentially contains saturated hydrocarbons, at a temperature below 1100 ⁰ C and a pressure of 0.1 to 50 ata in the presence of ·. steam is brought together with a catalyst containing zdrkonoxid, which has been produced from a starting material, at least part of which is amorphous zirconium oxide or a zirconium compound, which converts to amorphous zirconium oxide on heating, and that is 0.1 to 10 $ of an alkali compound, calculated as oxide. 2. The method according to claim 1, characterized in that the reaction is carried out at a temperature in the range from 200 to 90O ⁰ C. 3. The method of claim 1 or 2, characterized in that one carries out the reaction at a temperature in the range 500-850 ⁰ C. 4. The method according to claim 1 to 3 »characterized) that the reaction is carried out at a pressure in Range of 1-15 ata measured at the outlet of the reactor. - - 16 - 109827/1974 ~ ■: 5. The method according to claim 1 "to 4, characterized in that one uses a starting material, which consists entirely of a saturated hydrocarbon or a mixture of saturated hydrocarbons. 6. The method according to claim 1 Ms 4> thereby g e k e ή η -zeichen η. et that one uses a starting material, that a larger proportion of saturated hydrocarbons and contains a smaller proportion of unsaturated hydrocarbons. 7 «The method according to claim 1 to 6, characterized geke η η - ze i ch η et that the reaction is carried out in the presence of sulfur. 8. Process ^ aSE ¹¹ ?, 'Characterized in that sulfur is added to the starting material in ϊ ¹ or in of free sulfur, hydrogen sulfide, carbon disulfide or an organic sulfur compound. 9. The method of claim 1 to 8, characterized in that adding sufficient steam to give a weight ratio of steam to hydrocarbon feedstock in the Keaktor of * 0.01 to 10, in front of train svv ei se from 0.1 to 1.0, arises. Is 10. Zirkonoxidnaltiger catalyst for Surchführung of Yer- f ahrens according to claim 1 "to 9> characterized net gekennzeich he AASS from a starting material which at least partially amorphous zirconium oxide or which is converted upon heating into amorphous zirconium, a compound, together with 0.1 to 10 wt. = - ^ of an alkali blooming, calculated as oxide, is « - 17 - 10 3 8 2 7/137 L. 11, catalyst according to claim 10, characterized in that it contains 0.3 to 7 »0 S ^ by weight of an alkali compound, calculated as oxide. -12. Catalyst according to claim 10 or 11, characterized in that that in the starting material at least 15 $ of the zirconium oxide in the form of amorphous zirconium oxide or one Zirconium compound which is converted to amorphous zirconium oxide when heated. 13. Catalyst according to claim 12, characterized in that all of the zirconium oxide is amorphous zirconium oxide or a zirconium compound which is converted into amorphous zirconium oxide when heated is 14. Catalyst according to claim 10 to 13 »marked thereby draws that it is made of zirconium hydroxide or basic Zirconium carbonate has been produced. ι 109827/1374