NL8105117A - PREPARATION OF CATALYST MIXTURES. - Google Patents

Description

I

Κ 5591 NET

PREPARATION OF CATALYST MIXTURES

The invention relates to a process for the preparation of a catalyst mixture suitable for the conversion of a mixture of carbon monoxide and hydrogen into an aromatic hydrocarbon mixture. * Mixtures of carbon monoxide and hydrogen can be converted into an aromatic hydrocarbon mixture using a mixture of two catalysts, one of which is a zinc-containing composition which contains one or more of the metals chromium, copper and aluminum in addition to zinc and which composition has been prepared by calcining one or more precipitates obtained by adding a basic reactant to one or more aqueous solutions containing salts of the respective metals and the other being a crystalline metal silicate of special structure. Said crystalline metal silicates are characterized in that after calcining in air at 500 ° C for one hour, they have the following properties: a) thermally stable to a temperature of at least 600 ° C,

(b) an X-ray diffraction pattern showing the values shown in Table A.

20 listed four lines as strongest lines contains: 8105117 -2- • ¢ - ί

TABLE A

Relative d (A) intensity

11.1 +0.2 ZS

10.0 + 0.2 ZS

3.84 + 0.07 S

3.72 + 0.06 S

in which the letters used have the following meanings: ZS 83 very stark, S = strong, and c) in the formula representing the composition of the silicate expressed in moles of the oxides and in which, in addition to SiO2, one or more oxides of a trivalent metal A selected from the group consisting of aluminum, iron, gallium, rhodium, chromium and scandium, the SiO2 / A203 is mol. ratio more than 10.

In this patent application, a crystalline silicate with a thermal stability of at least t * C is understood to mean a silicate of which the X-ray powder diffraction pattern does not substantially change when heated to a temperature of t ° C.

The above catalyst mixtures have hitherto been used in the form of a coarse mixture which. was obtained by mechanically mixing particles of the zinc-containing composition and the crystalline silicate, each having an average particle size between 0.1 and 0.5 mm. Although the above-mentioned catalyst mixtures show a very acceptable behavior when used for the conversion of an H 2 / CO mixture into an aromatic hydrocarbon mixture, there is still a need to improve this behavior, in particular with regard to the C 5 + selectivity and the aromatics production.

8105117 'ί »-3-

Assuming that the aforementioned properties of the catalyst mixture could perhaps be improved by effecting a more intimate contact between the two components of the mixture, 5 single experiments were carried out using catalysts based on a fine mixture, which were catalysts obtained by individually grinding the original components of the mixture having an average particle size between 0.1 and 0.5 mm to an average particle size of less than 5 microns, mechanically mixing the obtained powders and pressing the mixture, and to be ground into particles with an average particle size between 0.1 and 0.5 mm · The results of these experiments were very disappointing. Although an improvement in the C5 + selectivity was observed, this was accompanied by a very sharp drop in activity as well as a drop in C31 selectivity and aromatics production.

Although, based on the above results, it had to be concluded that the chosen method to achieve a more intimate contact between the components of the mixture does not lead to the stated goal (improvement of the catalytic properties of the mixture), an attempt was nevertheless made daring to get to a more intimate contact between the components by other means. For this purpose, a preparation of the mixture by spray drying was chosen. Spray drying has been a commercially used method of preparing small spherical particles from a solid or mixture of solids for many years. The process is carried out by atomizing a water dispersion of the material to be spray-dried through a nozzle or from a rotating disk in a hot gas. The method is particularly suitable for a very close contact with 8105117 4. * ϊ -Ιμ- effect different substances.

The preparation of the present catalyst mixtures by spray drying is based on an aqueous dispersion in which, in addition to the crystalline slate, a zinc-containing precipitate was obtained, which had been prepared in the same manner as the previously mentioned precipitate, from which one of the two catalyst components was calcined and was prepared. By pressing the small spherical particles obtained during the spray drying and grinding the pressed XO material to an average particle size between 0.1 and 0.5 mm, a catalyst was obtained with excellent properties for the conversion of an H2 / CO mixture into a aromatic hydrocarbon mixture. Compared to the coarse mixture obtained by mechanical mixing described earlier, the mixture prepared by spray drying exhibited both a much higher 05 * selectivity and a much higher aromatics production. In view of the previously disappointing results on initial contact between the catalyst component and as obtained in the experiments with the catalysts prepared from the fine mixture, the result now obtained is considered surprising. The preparation of the present catalyst mixtures by spray drying is new.

The present patent application therefore relates to a process for the preparation of a catalyst mixture in which a crystalline metal silicate having the properties mentioned under a) - c) is dispersed in water together with one or more precipitates in which zinc and one or more metals are selected from chromium, aluminum and copper and which precipitates are obtained by adding a basic reacting agent to one or more aqueous solutions of salts of the respective metals and the desired catalyst mixture is prepared from the dispersion thus obtained by 8103117. Spray drying. In view of the shape, size and strength of the catalyst particles prepared according to the invention, they are very suitable for use in a fluidized state.

Although crystalline silicates containing several metals A can be used in the process according to the invention, preference is given to silicates in which only one metal A is present, and in particular to silicates which contain aluminum, XO iron or gallium as metal A. The crystalline silicates serve a SiO2 / Al2O3 mol. have a ratio greater than 10. Preferably, silicates with a SiO 2 / A 2 O 3 mol are used. ratio of less than 1000 and in particular between 20 and 500.

X5 The crystalline silicates are, among others, defined on the basis of the X-ray powder diffraction pattern. This should include the four lines listed in Table A as the strongest lines. The complete X-ray powder diffraction pattern of a typical example of a silicate usable in the process of the invention is shown in Table B.

810 5 11 7 "<·· ϊ -6-

Table Β d (A) Rel. int. d (A) Rel. int.

11.1 100 3.84 (D) 57 10.0 (D) 70 3.70 CD) 31 8.93 1 3.63 16 7.99 1 3.47 1 7.42 2 3.43 5 6 .68 7 3.34 2 6.35 11 3.30 5 5.97 17 3.25 1 5.70 7 3.05 8 5.56 10 2.9.8 11 5.35 2 2.96 3 4.98 (D) 6 2.86 2 4.60 4 2.73 2 4.35 5 2.60 2 4.25 7 2.48 3 4.07 2 2.40 2 4.00 4 (D) = doublet

The crystalline silicates can be prepared from an aqueous mixture containing the following compounds: one or more silicon compounds, one or more compounds containing a monovalent organic cation 5 (R) or from which such a cation is produced during the preparation of the silicate formed, one or more compounds containing a trivalent metal A and optionally one or more compounds of an alkali metal (M). The preparation is carried out by keeping the mixture at an elevated temperature until the silicate is formed and then separating the crystals of the silicate 8105117-7 from the mother liquor and washing, drying and calcining the crystals. In the aqueous mixture to which the silicates are prepared, the different compounds should be present in the following proportions expressed in moles of oxides: M20: SiO2 <0.35, R20: SiO2 »0.01 - 0.5,

SiO 2 i A 2 O 3> 10, and H 2 O: SiO 2 = 5 - 65.

If the preparation of the crystalline silicates is based on an aqueous mixture containing one or more alkali metal compounds, crystalline silicates containing alkali metal are obtained. Depending on the concentration of the alkali metal compounds in the aqueous mixture, crystalline silicates containing more than 1% by weight of alkali metal can be obtained.

Since the presence of alkali metal in the crystalline silicates adversely affects their catalytic properties, it is common practice to lower this content in crystalline silicates with a relatively high alkali metal content before using these silicates as catalysts. A reduction of the alkali metal content to about 200 gpm is sufficient for this. It has been found that a further reduction of the alkimetal content has virtually no influence on the catalytic properties of the silicate. The reduction of the alkali metal content of crystalline silicates can very suitably be effected by treating the silicates 25 one or more times with a solution of an ammonium compound. Here, alkali metal ions are exchanged for NH4 + ions and the silicate is converted into the NH4 + form. Calcination converts the NH4 + form of the silicate to the H + form.

In the preparation of the catalyst mixtures according to 8105117 * -8-, use is made of one or more precipitates in which zinc occurs together with one or more of the metals chromium, aluminum and copper and which precipitates are obtained by adding a 5 basic reacting substance to one or more aqueous solutions of salts of the relevant metals. Examples of metal combinations which are suitable for introduction via the precipitates into the catalyst mixtures to be prepared by spray drying are zinc-chromium, zinc-chromium-10 copper and zinc-aluminum-copper. Preferably, precipitates are used in which in addition to zinc, chromium is present, in particular precipitates in which the atomic percentage of zinc, based on the sum of zinc and copper, is at least 60% and in particular 60-80%. The metal-containing precipitates which are dispersed in water together with the crystalline silicate in the process of the invention can be prepared by precipitation of each of the metals individually or by co-precipitation of the desired metal combination. For example, for the preparation of a catalyst mixture in which the zinc-chromium metal combination is to be incorporated via the precipitates, it is possible to start from an aqueous solution of a zinc salt and an aqueous solution of a chromium salt, by adding a basic reactant to each of these solutions form a precipitate and the two precipitates, either as such or after prior mixing, disperse in water along with the crystalline silicate. The process according to the invention preferably uses a co-precipitate obtained by adding a basic reacting agent to an aqueous solution containing all the metals involved.

This co-precipitation is preferably carried out in a mixing cell with a continuous supply of an aqueous solution containing the respective metal salts and an aqueous solution of the basic reacting agent in stoichiometric amount based on the metals and with continuous discharge. of the co-precipitate formed. Before dispersing the metal precipitates together with the crystalline silicate in water, it is recommended to let them age in the mother liquor for some time and then wash them thoroughly with water. Suitable basic reactants which can be used in the preparation of the metal precipitates are ammonia, soda and alkali metal hydroxides. The basic reactants are preferably used in the form of an aqueous solution.

As for the ratio between the amounts of the metal-containing precipitate and the crystalline silicate in the dispersion from which the catalyst-mixture is prepared by spray-drying, it is preferred that it be chosen such that a catalyst mixture is obtained per wt. part of silicate 2.5-12.5 and especially 4-8 wt. parts of the metal oxides from the precipitate. Suitable conditions for carrying out the conversion of an H2 / CO mixture into an aromatic hydrocarbon mixture using a catalyst mixture prepared according to the invention are: a temperature of 200-500 ° C and in particular of 300-450 ° C, a pressure of 1-150 bar and in particular of 5-100 bar and a spatial flow rate of 50-5000 and in particular of 300-3000 N1 gas / 1 catalyst / hour. Preferably, an H2 / CO mixture with an H2 / CO mol is used as feed. ratio between 0.25 and 1.0. Such H2 / CO mixtures can very suitably be prepared 3q by steam gasification of a carbonaceous material such as coal, at a temperature of 900-1500 ° C and a pressure of 10-50 bar.

The above-described conversion of an H2 / CO mixture 8105117-10- into an aromatic hydrocarbon mixture can very suitably be used first. step of a two-step process for the conversion of H 2 / CO mixtures to hydrocarbon mixtures. In this case, carbon monoxide and hydrogen 5 present in the reaction product from the first step, if desired together with other components of this reaction product, are contacted in a second step with a catalyst containing one or more metal components with catalytic activity for the conversion of a H2 / CO mixture to 10 paraffinic hydrocarbons, which metal components are selected from the group consisting of cobalt, nickel and ruthenium, care must be taken to feed the second step a H2 / CO mol. ratio of 1.75-2.25.

The above-described conversion of an H2 / CO mixture

in an aromatic hydrocarbon mixture it is furthermore very suitable for use as the first step of a three-step process for the preparation of, inter alia, middle distillates from an H2 / CO mixture. In this case, carbon monoxide and hydrogen contained in the reaction product of the first step, if desired together with other components of this reaction product, are contacted in a second step with a cobalt catalyst containing zirconium, titanium or chromium to promote ensure that the feed for the second step is an H2 / CO

mol. ratio of 1.75-2.25. Of the reaction product of the second step, at least the part whose initial boiling point is above the final boiling point of the heaviest intermediate distillate desired as the final product is subjected to a catalytic hydrotreatment in a third step.

The invention is now illustrated by the following example.

8105117 y ”* ✓ -11-

Example

Catalytic preparation

Preparation of a Zn / Cr precipitate

Za (NO3) 2-6 aq and Cr (NO3) 3 «9 aq were dissolved in water in such amounts that a Zn / Cr solution was obtained containing 1.15 g ion Zn + Cr per liter and in which the Zn / Zn + Cr atomic ratio was 0.675. This solution was pumped together with a stoichiometric amount of a 10% aqueous NH3 solution with stirring through a mixing cell maintained at a temperature of 20 ° C. The volume of the mixing cell was 350 ml. The ratio of the feed rates was chosen so that the pH measured at the exit of the mixing cell was between 7 and 8. The pump speeds were chosen so that the volume flowed through was 100 l per hour. The Zn / Cr precipitate obtained was collected and aged at 20 ° C with stirring for dSn hours. yy The solid was filtered off and washed with water until the wash water was free from NO3 ”ions. The NO3 "free Zn / Cr precipitate thus obtained was divided into two portions A and B.

Catalyst 1 This catalyst was prepared by drying the above-mentioned portion A of the Zn / Cr precipitate at 120 ° C for 16 hours, grinding the dried material to an average particle size of 0.4 mm and the ground material for one hour to calcine in air at 400 ° C.

Catalyst 2

A crystalline aluminum silicate was prepared as follows. A mixture of NaOH, (C3H7) 4NQH, amorphous silica and NaA102 in water with the molar composition 3 3 Na 2 O. 4.5 [(03 ^) 4 ^ 20. SiO2. 0.04 AI2O3. 450 H 2 O was heated in an autoclave at 8103117 -12-150 ° C under autogenous pressure for 24 hours with stirring. After cooling the reaction mixture, the resulting silicate was filtered off, washed with water until the pH of the wash water was about 8 and dried at 120 ° C. After an hour of calcination in air at 500 ° C for 5 hours, the silicate had the following properties: a) thermally stable to a temperature of at least 900 ° C, b) an X-ray powder diffraction pattern substantially corresponding to that stated in Table 8, and 10 c) a SiO 2 / Al2 O3 mol. ratio of 225.

The silicate was boiled with a 1.0 molar NH4NO3 solution; washed with water, re-boiled with a 1.0 molar NH4NO3 solution and washed with water and dried at 120 ° C. Catalyst 2 was prepared by pressing and grinding the dried material to an average particle size of 0.4 mm and calcining the ground material in air at 500 ° C for one hour. Catalyst 3

For the preparation of catalyst 3, a crystalline aluminum silicate was started from, which after calcining in air at 500 ° C for one hour. had the following properties: a) thermally stable to a temperature of at least 800 ° C, b) an X-ray powder diffraction pattern substantially corresponding to that stated in Table B, and c) a SiO 2 / Al 2 O 3 mol. ratio of 290.

The silicate was boiled with a 1.0 molar NH4NO3 solution and washed with water. The silicate thus obtained was divided into two portions C and D.

Catalyst 3 was prepared by drying the above-mentioned portion C of the silicate at 120 ° C, pressing the dried material and grinding it to an average particle size of 0.4 mm and leaving the ground material for 35 hours. calcination in air at 500 ° C.

8105117 -13-

Catalyst mixture I

The catalyst mixture was prepared by mixing catalyst 1 and catalyst 2 in a wt. ratio of 10: 1.

Catalyst mixture II

This catalyst mixture was prepared by grinding catalysts 1 and 2 separately in a ball mill to an average particle size of less than 5 microns, mixing the crushed catalysts 1 and 2 very intimately in a weight ratio of 10: 1 and finally pressing and grinding mixture 10 to an average particle size of 0.4 mm ·,

Catalyst mixture III

This catalyst mixture was prepared by mixing catalyst 1 and catalyst 3 in a wt. ratio 15 of 5: 1.

Catalyst mixture IV

This catalyst mixture was prepared by grinding catalysts 1 and 3 separately in a ball mill to an average particle size of less than 5 microns, mixing the milled catalysts 1 and 3 very intimately in a 5: 1 weight ratio and finally mixing the mixture. pressing and grinding to an average particle size of 0.4 mm.

Catalyst mixtures V and VI

Portion D of the crystalline silicate was dried at 120 ° C for 16 hours and then calcined in air at 500 ° C for one hour. The material thus obtained was dispersed in water using a turbo stirrer to a concentration of 200 g per 30 liters. To the dispersion thus obtained, an amount of portion B of the Zn / Cr precipitate was added with stirring such that the wt. ratio of ZnO + Cr2O3 to the silicate in the dispersion was 5: 1.

8105117 ο ν '-1¾.

Finally, with stirring, so much water was added to the dispersion that its dry matter content was 15% by weight. Sedimentation of the dispersion was prevented by continuous stirring. The dispersion thus obtained was spray-dried in air in countercurrent operation using compressed air. The air inlet temperature was 300 ° C and the air outlet temperature was 120 ° C. The pressure used was 0.4 bar * The powder obtained, which consisted essentially of spherical particles with an average particle size of 50 microns and a bulk density of 1.33 g / ml,

was divided into two portions E and F. Catalyst mixture V was prepared from portion E by pressing, milling to an average particle size of 0.4 mm and calcining in air at 400 ° C for one hour. Catalyst mixture VI 15 was prepared from portion F by calcining in air at 400 ° C for one hour. V

The catalyst mixtures I-VX were tested for the preparation of an aromatic hydrocarbon mixture from an H2 / CO mixture. * The 20 IV catalyst mixtures were tested in a 50 ml reactor containing a solid catalyst bed with a volume of 7.5 ml. In five experiments, an H2 / CO mixture was mixed with an H2 / CO mol. ratio of 0.5 at a temperature of 375 ° C, a pressure of 60 bar and a spatial throughput rate of 850 Nl.kg. 1 hour passed over each of the catalyst mixtures IV. The results of the experiments averaged the first 100 hours are shown in table G.

8105117 -15-

Table C

Experiment No. 1 2 3 4 5

Catalyst mixture No. I II III IV V

Conversion of the synthesis gas, vol.% 60 41 60 45 55 C3 + selectivity based on G ^ +, weight% 93 89 93 88 93 C5 + selectivity based on C ^ +, weight Z 73 79 63 72 81

Composition of the C product, wt% paraffins 25 17 30 21 6 naphthenes 16 30 10 22 9 aromatics 59 52 60 57 85

The test of catalyst mixture VI was carried out in a vertically arranged fluid bed reactor with a height of 175 cm and a volume of 500 ml containing 215 ml of catalyst. The height of the catalyst-5 bed in non-expanded form was 75 cm. An H2 / CO mixture with an H2 / CO mol. ratio of 0.5 at a temperature of 385 ° C, a pressure of 60 bar and a superficial gas velocity of 3 cm / sec. (corresponding to a spatial throughput of approximately 3000 Nl.kg “^. hour” *) 10 contacted with catalyst mixture VI. The results of this experiment (experiment 6) on average for the first 50 hours are shown in Table D.

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Table D

*

Experiment No. 6

Catalyst Mixture No. VI

Conversion of the synthesis gas, vol.% C3 + selectivity based on Ci +, wt. % 93 C5 + selectivity based on 0χ +, wt% 78

Composition of the Gq + product, wt% paraffins 14 naphthenes 23 aromatics 63

Research octane number (RON-O) of the C5 * fraction 98

The following can be noted with the results listed in Table C.

a) Of the catalyst mixtures I-V, only the catalyst mixture V was prepared according to the invention. The remaining 5 catalyst mixtures are outside the scope of the invention. They are included in the patent application for comparison.

b) Of experiments 1-5, only experiment 5 was performed using a catalyst mixture 10 prepared according to the invention.

c) Comparing the results of Experiment 1 (with a 10: 1 coarse catalyst mixture) and Experiment 2 (with a 10: 1 fine catalyst mixture) clearly shows the negative influence of the intimate mixing on the activity, the C3 + selectivity and aromatics production.

d) A similar effect can be seen when comparing the results of experiment 3 (with a 5: 1 coarse catalyst mixture) and experiment 4 (with a 5: 1 fine catalyst mixture).

e) Comparing the results of experiment 3 (with 8105117 -17- * a 5: 1 coarse catalyst mixture) and experiment 5 (with a 5: 1 catalyst mixture prepared by spray drying) clearly shows the very strong positive influence of the preparation by spray drying on the C5 + selectivity 3 and aromatics production

The following can be noted with the results listed in Table D. In the fluid bed experiment 6 which was carried out using a catalyst mixture prepared according to the invention, despite the very high spatial throughput used, a very attractive C5 + product with high aromatics content and high octane number was obtained.

8105117

Claims (13)

1. Process for preparing a catalyst mixture, characterized in that a crystalline metal silicate which, after a calcination in air at 500 ° C, has the following properties: 5 a) thermally stable! to a temperature of at least 600 ° C, b) an X-ray diffraction pattern containing the four lines listed in Table A as the strongest lines: TABE-L A Relative d (A) intensity 11.1 + 0.2 ZS 10.0 + 0, 2 ZS 3.84 + 0.07 S 3.72 + 0.06 S in which the letters used have the following meanings: ZS = »very strong, S = stark, and 10 c) in the formula showing the composition of the silicate expressed in moles of the oxides and in which, in addition to SiO2, one or more oxides of a trivalent metal A selected from the group consisting of aluminum, iron, gallium, rhodium, chromium and scandium are present, the SiO2 / A203 is mol. ratio greater than 10, is dispersed in water along with one or more 8103117 «-sr» - ή »♦ · -19- more precipitates containing zinc and one or more of the metals chromium, copper and aluminum and which precipitates have been prepared by adding one or more aqueous solutions of salts of the relevant metals to a basic reacting agent and preparing the desired catalyst mixture from the dispersion thus obtained by spray drying. 2. Process according to claim 1, characterized in that the crystalline silicate contains only a trivalent metal A10 selected from the group formed by aluminum, iron and gallium. Process according to claim 1 or 2, characterized in that the crystalline silicate has a SiO 2 / A 2 O 3 mol. ratio has between 20 and 500. 4. Process according to any one of claims 1-3, characterized in that a co-precipitate is obtained which is obtained by adding a basic reacting agent to an aqueous solution containing all the metals involved. 5. Process according to claim 4, characterized in that the co-precipitation is carried out in a mixing cell with continuous supply of an aqueous solution containing the respective metal salts and an aqueous solution of the basic reacting agent in a stoichiometric amount based on the metals and with continuous removal of the co-precipitate formed. 6. Process according to any one of claims 1-5, characterized in that a precipitate is used which, in addition to zinc, contains chromium and wherein the atomic percentage of zinc, based on the sum of zinc and chromium, is 60-80%. Process according to any one of claims 1 to 6, characterized in that the ratio between the amounts of metal-containing precipitate and crystalline silicate in the dispersion is chosen such that after spray drying a catalyst 8105117 «V- - -w -20- * mixture is obtained which per wt. part silicate, 4-8 wt. parts of the metal oxides from the precipitate. 8. Process for the preparation of a catalyst mixture, substantially as described above and in particular with reference to the preparation of the catalyst mixtures V and VI from the example. Catalyst mixtures prepared according to a method as described in claim 8. ΙΟ 10. Process for the preparation of an aromatic hydrocarbon mixture. by contacting an H2 / CO mixture with a catalyst mixture according to claim 9. 11. Process according to claim 10, with the boulder brand, that the catalyst mixture is used in a fluidized state. Process according to claim 9 or 10, characterized in that the H2 / CO mixture is an H2 / CO mol. ratio has between 0.25 and 1.0. 13. Hydrocarbon mixtures prepared by a method as described in any one of claims 10-12. 8105117