NL7905480A - METHOD FOR PREPARING CATALYSTS - Google Patents

Description

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κ 5516 IT

Applicant: Shell Internationale Research Maatschappij B.V.

Carel van Bylandtlaan 30, * The Hague

Short designation: Process for the preparation of catalysts.

The invention relates to a process for the preparation of new Fischer-Tropsch catalysts.

The preparation of hydrocarbons from a mixture of carbon monoxide and hydrogen by contacting this mixture with an catalyst at elevated temperature and pressure is known in the art as the Fischer-Tropsch hydrocarbon synthesis. Catalysts frequently used for this purpose contain one or more iron group metals together with one or more promoters and sometimes a support material. The preparation of the Fischer-Tropsch catalysts can in principle be carried out in three ways, namely by precipitation, by melting or by impregnation. Briefly, the preparation of the catalysts by precipitation amounts to making basic an aqueous solution of an iron group metal salt to which, optionally, a salt of a promoter and a support material may be added, whereby the catalyst is precipitated originate. One or more pro-motors and a support material may be added to this precipitate. The preparation of the catalysts by melting takes place, for example, for iron catalysts by fusing iron oxide with one or more promoter oxides. Both the precipitation route and the melting route are not very attractive preparation methods for the Fischer-Tropsch catalysts since their reproducibility is low. Moreover, the precipitation route is very time consuming, while the melting route requires a lot of energy. Also the catalytic properties of the 790 5 4 80% prepared by melting and precipitation. Catalysts, especially activity and stability, often leave much to be desired. A much more attractive preparation method for the Fischer-Tropsch catalysts is the impregnation route. This is easy to implement, gives good reproducible results and as a rule leads to catalysts with high activity and stability. Briefly, the impregnation route is to impregnate a porous support with one or more aqueous solutions of salts of one or more iron group metals and of one or more promoters followed by drying, calcining and reducing the composition. Many elements such as alkali metals, alkaline earth metals, Group VI B, Ti, Zr, Th, V, Mn and Cu metals are suitable promoters for the catalysts prepared by impregnation. Both amorphous and crystalline materials are suitable as support materials for the catalysts prepared by impregnation. Suitable carriers include silica, alumina, zirconia, thoria, boria as well as combinations thereof such as silica-alumina and silica-magnesia and further zeolites such as mordenite, faujasite and zeolite omega.

The Applicant has conducted an extensive investigation into the preparation of hydrocarbons from H 2 / CO mixtures with an H 2 / CO mole. ratio less than 1.0 using Fischer-Tropsch catalysts prepared by impregnation. It has been found that the behavior of these catalysts during the above conversion is strongly dependent on the following factors: 1) the nature of the metal from the iron group and the loading used, .30 2) the nature of the promoter and the loading used. , 3) the nature of the support, and 4) the temperature treatment used.

It has been found that catalysts prepared by impregnation have a

790 5 4 SC

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exhibit very high activity and very high stability for the conversion of H 2 / CO mixtures with an H 2 / CO mole ratio of less than 1.0 if they are 30-75 wt. parts of iron and 5-40 wt. parts of magnesium per 100 wt. parts 5 contain alumina and at a temperature of 700-1200 ° C

are calcined. These catalysts are new.

The present patent application therefore relates to a process for the preparation of new catalysts, wherein catalysts containing 30-75 wt.

10 parts of iron and 5-40 wt. parts of magnesium per 100 wt.

parts of alumina are prepared by impregnating an alumina support with one or more aqueous solutions of iron and magnesium salts followed by drying the composition, calcining at a temperature of 700-1200 ° C and reducing. The patent application further relates to the use of these catalysts for the preparation of hydrocarbons from an H 2 / CO mixture with an E 2 / CO mole. ratio smaller 2o 1.0.

When using the catalysts prepared according to the invention for the above-mentioned application, preference is given to catalysts having 40-60 wt. parts of iron and 7.5-30 wt. parts of magnesium per 100 wt. parts alumina 25. There is also preference for catalysts which, in addition to iron and magnesium, contain a reduction promoter and a selectivity promoter. A suitable reduction promoter is copper. Suitable selectivity promoters are the alkali metals, in particular potassium. In the catalyst preparation according to the invention, in addition to iron and magnesium, 0.5-wt. parts copper and 1-5 wt. parts of potassium per 100 wt. parts of alumina are incorporated into the catalyst by impregnation.

In the preparation of the catalysts, the metal salts can be applied to the support in one or more steps 7905480% -4-. Between the impregnation steps, the material is dried and optionally calcined. The use of a multi-stage impregnation may be necessary for the preparation of catalysts with a high metal loading. The metal salts can be applied separately to the support or together from one solution. An attractive method of applying the metal salts to the support is the dry impregnation technique, according to which a support is contacted with an aqueous solution of the respective salts, the aqueous solution having a volume which substantially corresponds to the pore volume of the carrier. Absorption of the aqueous solution by the carrier can be facilitated by heating the mixture. If this method is chosen for the preparation of high metal loading catalysts, it may be necessary to perform more than one dry impregnation and dry the material between the individual impregnation steps and optionally calcine. The requirement to use a calcination temperature of 700-1200 ° C only concerns the calcination immediately prior to the reduction. If several calcinations are carried out in the catalyst preparation, for example between different impregnation steps, these calcinations can be carried out at a lower temperature, if desired. The calcination immediately prior to the reduction is preferably carried out at a temperature of 750-850 ° C. The catalyst preparation is completed with a reduction. This reduction is carried out at an elevated temperature with a hydrogen-containing gas, for example, a mixture of hydrogen and nitrogen. The reduction is preferably carried out at a temperature of 250-350 ° C.

The catalysts prepared according to the invention are ideally suited for the preparation of hydrocarbons starting from an R 1 / CO mixture with an H 2 / CO mol. ratio 7905480-5 less than 1.0. Such /Η / CO mixtures can very suitably be prepared by steam gasification of a carbonaceous material. Examples of such materials are brown coal, anthracite, coke, crude oil and fractions thereof, as well as oils obtained from tar sand and bituminous slate. The steam gasification is preferably carried out at a temperature of 900-1500 ° C and a pressure of 10-50 bar.

The preparation of hydrocarbons from a 10 H 2 / CO mixture with an H 2 / CO mole. ratio less than 1.0 using a Fischer-Tropsch catalyst according to the invention is preferably carried out at a temperature of 200-350 ° C and in particular of 250-350 ° C, a pressure of 10-70 bar and in in particular from 20-50 bar and a spatial throughput of 500-5000 and in particular from 500-2500 NI gas / 1 catalyst / hour. The hydrocarbon preparation according to the invention can very suitably be carried out by feeding upwards or downwards through a vertically arranged one. Lead a reactor in which there is a fixed or moving bed of the relevant catalyst.

The invention is now illustrated by the following example.

Example 25 11 catalysts (A-H and 1-3) were prepared and tested for Fischer-Tropsch hydrocarbon synthesis. The preparation of the catalysts was carried out by impregnating an alumina or silica support with aqueous solutions containing one or more of the following salts: iron nitrate, magnesium nitrate, copper nitrate and potassium nitrate. All impregnations made use of the dry impregnation technique. The reduction of the catalysts was carried out at atmospheric pressure with a mixture in a volume ratio of 3 * 1 at a superficial gas velocity of 1.6 m / see. Further information on the preparation of the individual catalysts follows below.

790 5 Λ 80 -6- t ''

Catalyst A

This catalyst was prepared by first impregnating an alumina support with a solution of MgOJO 2, followed by drying at 120 ° C and calcining at 400 ° C for 2 hours and then impregnating with a solution of Fe 2 O 4.

CuCNO2) and KNO2 followed by drying at 120 ° C, calcination at 400 ° C for 2 hours and reduction at 280 ° C.

Catalyst B

The preparation of this catalyst was carried out essentially in the same manner as that of catalyst A, with the exception that after the second calcination at 400 ° C, another calcination was carried out at 800 ° C for 14 hours.

Catalyst C

The preparation of this catalyst was carried out essentially in the same manner as that of catalyst A, with the difference that in the second impregnation a solution was used with a higher concentration of Fe,

Cu and K and that the second calcination was carried out at 650 ° C for 16 hours.

20 Catalyst D

This catalyst was prepared by impregnating an alumina support with a solution of Mg (NO ^) 2> Fe (NO ^) ^, Cu (NO ^) 2 and KNOg followed by drying at 120 ° C, calcining at 400 ° for 2 hours C and reduction at 280 ° C.

Catalyst E

The preparation of this catalyst was carried out essentially in the same manner as that of catalyst D, except that a solution was used with a higher concentration of Fe, Cu and K which did not contain Mg and that the calcination for 14 hours at 800 ° C was performed.

Catalyst F

The preparation of this catalyst was carried out essentially in the same manner as that of catalyst D, with the difference that silica was used as the carrier, that a solution was used with a higher concentration of Fe, Cu and K and that the calcination at 800 ° C for 14 hours was performed.

Catalyst G

The preparation of this catalyst was carried out essentially in the same manner as that of catalyst D with the difference that a solution was used with a higher concentration of Mg, Fe, Cu and K and that the calcination was carried out at 800 ° C for 14 hours. executed.

Catalyst H

The preparation of this catalyst was carried out essentially in the same manner as that of Catalyst A, except that the reduction was carried out at 400 ° C.

Catalyst 1

The preparation of this catalyst was carried out essentially in the same manner as that of Catalyst A, except that in the second impregnation a solution 20 was used with a higher concentration of Fe, Cu and K, the second calcination for 16 hours at 800 ° C was performed and the reduction was performed at 325 ° C.

Catalyst 2

The preparation of this catalyst was carried out essentially in the same manner as that of Catalyst A, except that in the first impregnation a solution with a higher concentration of Mg was used, in the second impregnation a solution with a higher concentration was used. concentration of Fe, Cu, and K, that the second calcination was carried out at 800 ° C for 16 hours and that the reduction was carried out at 300 ° C.

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Catalyst 3

The preparation of this catalyst was carried out essentially in the same manner as that of Catalyst A, except that the calcination was omitted after the first impregnation step, the second impregnation used a solution with a higher concentration of Fe , Cu and K, that the calcination after the second impregnation was carried out at 800 ° C for 16 hours and that the reduction was carried out at 325 ° C.

The composition of the catalysts is reported in

table A

Table A

Cat.nr. Composition expressed in wt. share

Fe Mg Cu K a12 ° 3 Si ° 2 15 A 25 20 1.25 2 * 100 B 25 20 1.25 2 100 C 50 20 2.5 4 100 D 25 20 1.25 2 100 E 50 2.5 4 100 20 F 50 20 2.5 4 ~ 100 G 50 50 2.5 4 100 H- 25 20 1.25 2 100 1 50 20 2.5 4 100 2 50 10 2.5 4 100 25 3 60 20 3 4 100

Testing of Catalysts A-H and. 2 and 3 for the Fischer-Tropsch hydrocarbon synthesis, starting from synthesis gas with an H2 / CO mol. 0.5 ratio took place in a 250 ml reactor containing a catalyst bed with a volume of 50 ml. The experiments were performed at a temperature of 280 ° C, a pressure of 30 bar and a spatial throughput -1 -1 -1 speed of 1000 µl.

The results of these experiments are shown in Table B.

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Table B

Exp.nr. Cat.nr. Conversion of the synthesis gas,%

After 25 hours After 500 hours 1 A 75 5 2 B 28 3 C 87 37 4 D 64 5 E 71 6 F 74 10 7 G 69 8 H 76 9 2 91 89 10 3 92 89

Catalyst 1 was tested for 3150 hours for the Fischer-Tropsch hydrocarbon synthesis starting from a synthesis gas with an H 2 / CO mol. ratio of 0.6. The experiment (exp. 11) was performed essentially in the same manner as experiments 1-10, except that the experiment was continued over a longer period of time with temperature and spatial throughput

were varied. The results of experiment 11 as well as the reaction conditions used are shown in Table C.

Table C

Conditions during the experiment Result_ 25 Period Temperature, Spatial Op run Conversion of the synthesis run hours in C transit hours, speed, gas,%

En ~ .hours ”0-25 280 1000 25 93 30 25-500 280 1000 500 90 500-900 280 1000 900 85 900-1350 270 500 1350 80 1350-1850 280 500 1850 80 1850-2300 295 500 2300 85 35 2300-2800 305 500 2800 81 2800-3150 305 350 3150 80 7905480 -10-

Of the experiments listed in Tables B and C, only Experiments 9-11 were performed with catalysts prepared according to the invention. In these experiments, the catalysts showed both very high activity and very high stability. Experiments 1-8 were conducted with catalysts outside the scope of the invention. They are included in the patent application for comparison.

Catalysts A, D and H contained too little iron and were calcined at too low a temperature. The results of experiments 1, 4 and 8 show that these catalysts had a low activity.

Catalysts B, E, F and G contain resp. too little iron, no magnesium, no alumina and too much magnesium.

The results of experiments 2, 5, 6 and 7 show that these catalysts had a low activity.

Catalyst C was calcined at too low a temperature. The results of experiment 3 show that although this catalyst had a high activity, it had a very low stability.

7905450

Claims (19)

Process for the preparation of catalysts, characterized in that catalysts containing 30-75 wt. parts of iron and 5 wt% wt. parts of magnesium per 100 wt. parts of alumina are prepared by impregnating an alumina support with one or more aqueous solutions of salts of iron and of magnesium followed by drying the composition, calcining at a temperature of 700-1200 ° C and reducing. 2. Process according to claim 1, characterized in that a catalyst is prepared containing 40-60 wt. parts of iron per 100 wt. parts alumina. 3. Process according to claim 1 or 2, characterized in that a catalyst is prepared which contains 7-5-30 wt. parts of magnesium per 100 wt. parts alumina. Process according to any one of claims 1-3, characterized in that a catalyst is prepared which additionally contains a reduction promoter. Process according to claim 4, characterized in that a catalyst is prepared which contains 0.5-5 wt. parts of copper 20 per 100 wt. parts alumina. Process according to any one of claims 1 to 5, characterized in that a catalyst is prepared which additionally contains a selectivity promoter. 7. Process according to claim 6, characterized in that a catalyst is prepared which contains 1-5 wt. parts of potassium per 100 wt. parts alumina. Process according to any one of claims 1 to 7, characterized in that the preparation of the catalyst is carried out according to the dry impregnation technique. 790 54 80 -12- Process according to any one of claims 1-8, characterized in that the calcination is carried out at a temperature of 750-800 ° C. 10. A method according to any one of claims 1-9, characterized in that the reduction is carried out at 250-350 ° C. 11. Process for the preparation of catalysts, essentially as described above and in particular with reference to the preparation of catalysts 1-3 in the example. tt Catalysts prepared according to a method as described in claim 11. 13. Process for the preparation of hydrocarbons from an H- / CQ mixture, characterized in that an H_ / C0 mixture. with an H2 / C0 mol. ratio of less than 1.0 at elevated temperature and pressure is contacted with a catalyst according to claim 12. Method according to claim 13, characterized in that it is applied to an H2 / CO mixture obtained during the steam gasification of a carbonaceous material. Method according to claim 14, characterized in that the steam gasification of the carbonaceous material is carried out at a temperature of 900-1500 ° C and a pressure of 10-50 bar. 16. Process according to any one of claims 13-15, characterized in that the preparation of the hydrocarbons from the H2 / CO mixture is carried out at a temperature of 200-350 ° C, a pressure of 10-70 bar and a spatial throughput of 500-5000 NI gas / 1 catalyst / hour. 17. Method according to claim 16, characterized in that it is carried out at a temperature of 250-350 ° C, 7905480. 1 -13- a pressure of 20-50 bar and a spatial flow rate of 500-2500 NI gas / 1 catalyst / hour. 18. Process for the preparation of hydrocarbons from an H 2 / CO mixture with an H 2 / C0 mol. ratio less than 1.0, essentially as described above and particularly with reference to experiments 9-11 in the example. 19. Hydrocarbons prepared by a process as described in claim 18. 7905480