A method of producing a catalyst for the conversion of synthesis gas composition, catalyst and method of synthesis gas

 

(57) Abstract:

Describes how to obtain a catalyst containing an inert carrier, cobalt, ruthenium, and a third element selected from scandium and yttrium. The method includes at least the following stages: the first catalytic previous product (A) containing cobalt and an inert carrier, followed by calcination, restoration and passivation; obtaining a second catalytic previous product (B) containing cobalt, ruthenium and an inert carrier, by deposition of ruthenium on the first catalytic product (A) with subsequent annealing, recovery and passivation; obtain the final catalyst by deposition of an element selected from scandium and yttrium, catalytic previous product (C) with subsequent annealing, recovery, and passivation. Also described composition for the preparation of the catalyst, the catalyst and the method of synthesis gas. The technical result - obtaining catalyst is particularly effective in the conversion of synthesis gas to hydrocarbon products containing significant amounts of hydrocarbons with the number of carbon atoms greater than or equal to 22. 4 C. and 5 C.p. f-crystals, take 2 tablets in the conversion of synthesis gas according to the method of Fischer-Tropsch, i.e. in receipt of primarily liquid hydrocarbons from mixtures of CO and H2.

More specifically, the object of the present invention is a method of producing catalyst, mainly consisting of Co, Ru, and a third element selected from scandium and yttrium, and deposited on an inert carrier.

The choice of cobalt due to the fact that cobalt promotes the formation of saturated products with high molecular mass at a lower temperature compared to, for example, systems based on iron.

The use of catalysts based on cobalt return to the first works of Fisher in 1932 (N. H Storch, N. Golumbic and R. B. Anderson, "The Fischer Tropsch and Related Synthesis", John willey & Son, Jnc., New York, 1951), where he developed the system Co/Th2/MgO/kieselguhr.

Subsequently, the development of such systems has led to the identification of the nature of different promoters to be added to the cobalt to increase the selectivity to hydrocarbons with high molecular weight, and it occurred mainly in the last twenty years. In fact, the increase in oil prices in the 70-ies stimulated the study of other ways to produce liquid fuels and chemical products.

In the patent US-A-4088671 described catalyst for synthetically more than the second.

In the patent US-A-4413064 described catalyst to the reactor with a porous layer mainly consisting of cobalt, ruthenium and thorium or lanthanum oxide supported on alumina, obtained by impregnation of alumina with an aqueous solution of salts of cobalt and subsequent non-aqueous organic impregnation with ruthenium salt and the salt of a metal belonging to group IIIB or IYB. Among the metals of these groups in the patent US-A-4413064 are also scandium and yttrium, but the preferred metals are thorium and lanthanum. The above catalyst is particularly effective in the conversion of synthesis gas to produce a hydrocarbon product with a high content of paraffin hydrocarbons having a boiling point in the field of diesel fuel, i.e., the product of C9-C21. In the patent US-A-4413064 there is no information about the ability of the described catalysts to the creation of heavier hydrocarbons, the process of obtaining which is preferred in comparison with the process of obtaining hydrocarbon with a boiling point in the field of diesel fuel.

A method was discovered for the preparation of the catalyst on an inert carrier, consisting mainly of larger amounts of cobalt and fewer ruthenium and ogorodnya products containing significant amounts of hydrocarbons with the number of carbon atoms greater than or equal to 22.

Thus, the present invention relates to a method of producing a catalyst mainly composed of inert carrier selected from at least one oxide of at least one element selected from Si, Ti, Al, Zr, Zn, Mg, Sn, preferably silicon, and (in the form of elements or oxides) more cobalt and fewer ruthenium and a third element selected from scandium and yttrium, characterized in that it includes at least the following stages:

(1) the receipt of the first catalytic previous product (A) containing cobalt and at least part of the inert carrier by deposition of cobalt on an inert carrier, followed by calcination, restoration and passivation inert carrier containing cobalt;

(2) obtaining a second catalytic previous product (B) containing cobalt, ruthenium and at least part of the inert carrier by deposition of ruthenium on the first catalytic previous product (A) with subsequent annealing, recovery and passivation inert carrier containing ndia and yttrium, on catalytic previous product (C) with subsequent annealing, recovery and passivation inert carrier containing cobalt, ruthenium and the third element.

Another object of the present invention is a catalyst which can be obtained as described above.

In the method according to the present invention stage 1 consists of an initial deposition of cobalt on at least part of the inert carrier, preferably on all inert carrier. This deposition, and the deposition of ruthenium on stage 2 and the third element on the stage 3 can be performed by various methods known to experts in the art, for example by exchange, impregnation, dry impregnation (also known as initial hydration), deposition, gilotinirovaniya and mechanical mixing. In a preferred embodiment, the deposition of cobalt on the stage 1 is performed by the method of dry impregnation. In accordance with this method, the applied material is introduced into contact with the solution is approximately equal to the pore volume. In stage 1 is preferred to use aqueous solutions of cobalt salts. Can be used cobalt salts of any type, for example the halides, the config with lactic acid and lactates, the complex formed with tartaric acid and tartratami, the complex formed another policistoj or hydroxycitrate and the corresponding salts, the complex formed with acetylacetonates.

After deposition of inert carrier of the required quantity of cobalt salt, preferably cobalt nitrate, followed by a stage of annealing, then the recovery phase and then stage passivation. In accordance with another option before calcining the impregnated carrier is subjected to drying to remove most of the water. This drying can be carried out at temperatures in the range between 10 and 30oC and then at temperatures between 100 and 120oC, preferably in the presence of gas flow.

In stage 1, the annealing is carried out at a temperature in the range between 300 and 500oC, preferably between 350 and 450oC, in air, in order to remove all organic debris.

Calcined specified product is then subjected to the recovery environment, mainly consisting of hydrogen, at a temperature in the range between 300 and 500oC, preferably between 350 and 450oC. Is preferred gradually brings the P>C / minute. Typically, the restore operation is complete when the above temperature for the period of time between 10 and 20 hours at the rate of H2between 1 and 3 liters per hour per gram of catalyst. At the end of the restore, perform the operation of passivation in the presence of oxygen diluted with an inert gas (usually nitrogen), preferably at a temperature in the range between 10 and 80oC. using, for example, nitrogen containing 1-2% O2(flow rate of 2 liters per hour), this operation may take 1-5 hours at 25oC. it is Obvious that at the end of recovery (and, of course, before passivation) the sample should be chilled.

The second stage of the method according to the present invention consists in the deposition of ruthenium on the catalytic previous product (A) obtained after the end of stage 1.

In contrast to stage 1 in this case is preferred to precipitate ruthenium impregnated with organic solutions of salts of ruthenium. For example, you can use the ruthenium nitrate, dissolved in acetone and/or ethanol.

As in stage 1, after deposition followed by annealing, recovery, and then the passivation. But in this case it is preferred about the war between 200 and 400oC, preferably between 250 and 350oC. Restoration and passivation is carried out at the same temperature conditions as in stage 1.

At the end of the second stage catalytic get a predecessor product (In), mainly formed by cobalt and ruthenium deposited on an inert carrier.

The third (and last) stage of the method according to the present invention consists in depositing on the previous product (C) obtained after the second stage, the third element selected from yttrium and scandium. In one embodiment, use of nitrate of scandium or yttrium, dissolved in a solvent selected from acetone, lower alcohols, water and mixtures thereof. As for the calcination, reduction and passivation, using the same conditions as described for stage 2. The catalytic composition, which can be obtained by the method according to the present invention contains (in the metallic form or in the form of a derivative), EN (in metallic form or in the form of a derivative) and at least a third additional element (also in the metallic form or in the form of derivative) is selected from Sc, and Y, all of these elements dispersed on the carrier and, if they are present media consists of, at least oxide selected from at least one of the following elements: Si, Ti, Al, Zr, Zn, Mg. In a preferred embodiment, the inert carrier is silicon dioxide.

The content of these elements in the final catalyst, expressed for metals in mass percent in comparison with the mass of the catalyst is changed in the following ranges:

Range

Co - 1-50%

EN - 0,05-5%

The third is 0.5 - 5%

Preferred ranges

Co - 3-35%

EN - 0,1-3%

Third - 0,1-3%

As already mentioned, the present invention also concerns the method of producing hydrocarbons from synthesis gas in the presence of the above catalyst system.

As for the Fischer-Tropsch synthesis, it can be seen as a way hydrogenation of carbon monoxide with the aim of obtaining higher hydrocarbons, mainly linear chain. In the Fischer-Tropsch synthesis selectivity of hydrocarbon products is determined by the ability of the catalyst to promote the reaction of the development of the hydrocarbon chain relative to the end of the segment chain. The distribution of hydrocarbon products can be described in terms of "curing" type mechanism of chain growth, developed by Schultz and WMD Anderson (R. B. Anderson, Catalysis, vol. IV, P. H. Emmet ed. , Reinhold, New York, 1956). The model, called the model of the Anderson-Schulz-Flory (ASF, ASF), elaborated on a statistical basis relative to the growth of the chain, alpha (), and imposes three conditions:

1. Chain growth should occur by the addition of intermediate products with only one carbon atom.

2. Open circuit should occur in the simple desorption from the circuit, for example, hydrogen extraction.

3. Growth factor independent of chain length.

The mathematical representation is given by the following formula:

Wn= (1-)2-(n-1),

where n is the number of carbon atoms in the product, Wn- mass fraction of product and alpha () is the growth factor, which has values between 0 and 1.

From the expression in logarithmic form:

logWn/n = nlog+log[(1-)2/]

you can get alpha as the slope of the linear relationship between log Wn/n and n.

The values of the growth factor alpha affect both reaction conditions and catalyst composition. Usually the lower the reaction temperature causes an increase in selectivity to liquid hydrocarbons (C5), but inevitably reduces the degree of conversion of synthesis gas (CONV. CO). Sushestvujusih the exact scope of the feasibility of the used reaction conditions. But at low temperatures it is possible to exceed these limits, using the catalytic system, particularly selective with respect to hydrocarbon fractions with high molecular weight (for example, C25+).

The present invention relates, therefore, to a catalytic composition, which allows you to convert a mixture of CO and H2known as synthesis gas, essentially unbranched saturated hydrocarbon with the percentage of hydrocarbon, C25+between 22.5 and 31% by weight and the values of the growth factor alpha in excess of 0.90.

Conditions such catalysts are known in the art as conditions for Fischer-Tropsch synthesis.

Conversion of synthesis gas to hydrocarbons occurs at a pressure typically in the range between 0.1 and 15 MPa, preferably between 1 and 10 MPa, at a temperature usually in the range between 150 and 350oC, preferably between 170 and 300oC.

The volumetric rate per hour is normally in the range between 100 and 20,000, preferably between 400 and 5,000 (the amount of synthesis gas to volume of catalyst per hour); the relation of H2/CO in the synthesis gas is normally in the range between 1:2 and 5:1, preferably between 1.2:1 and 2.5:1.

As an example, we can recall that the catalysts of the present invention can be used in a reactor with a fixed catalyst bed, continuously fed with a mixture of CO and H2and working under the following conditions:

the reaction temperature 200-215oC;

- pressure reactions 20 bar;

- the volumetric rate of 500 h-1;

a mixture of H2/CO 2/1.

The catalysts obtained in examples 1-6 and having the compositions shown in table 1, were evaluated under specified conditions. The results of the tests on the chemical activity are given in table 2.

Example 1. Catalyst A (for comparison)

Use silica with surface area 300 m2/g, specific pore volume of 1.3 cm3/g, a particle diameter of 20 μm and a specific gravity 0,388 g/cm3. oC for 16 hours, in such quantities as to obtain the percentage of Co is equal to 15% by weight relative to the entire catalyst. Impregnated in this way silicon dioxide calcined at 400oC in air for 4 hours and then treated in a stream of H2with a bulk velocity (GHSV - hourly average gas flow rate) 1000 h-1in a tubular reactor at 400oC for 16 hours. Restored thus the sample Passepartout in a mixture (1%) O2/(99%)OF N2at an average hourly rate of gas supply 1000 h-1for 2 hours at room temperature.

On the monometallic sample Co/SiO2add 7,5 10-3M solution of Ru(NO3)3H2O obtained by performing the following operations: precipitation as hydroxide with a pH of 7.2 RuCl3H2O elimination of chlorides, re-dissolution in concentrated HNO3and dilution in CH3COCH3in the ratio of 1:250 (volume/volume).

Add to the sample solution of ruthenium in acetone in such quantity to be 0,2% Ru by weight relative to the total mass. The slurry is mixed for two hours, then dried under vacuum at 40o

(Catalyst: Co/Ru/SiO2, 15%, And 0.2% EN)

Example 2. The catalyst IN

To obtain the catalyst In 50 g of catalyst And add 10-3M solution Y(NO3)3in acetone in such amount to obtain a final mass percent yttrium content of 0.2%.

Obtained when the slurry is mixed for two hours and then dried under vacuum at 40oC. Next, the sample calcined at 300oC for 4 hours in air, restore 400oC in H2at an average hourly rate of gas supply, equal to 1000 h-1and Passepartout in a mixture (1%) O2/(99%) OF N2at an average hourly rate of gas supply 1000 h-1at room temperature.

(Catalyst: Co/Ru/Y/SiO2, 15% Co, 0.2% of Ru, and 0.2% y)

Example 3. Catalyst C

Obtaining catalyst C is different from that described in example 2 using 10-3M solution of Sc(No3)3in acetone to the extent that the final mass percentage of scandium, equal to 0.2%.

(Catalyst: Co/EN/Sc/SiO2, 15% Co, 0.2% Of Ru, And 0.2% Sc.)

Example 4. Catalyst D

Obtaining catalyst D is different from that described in primeomega mass percentage of scandium, equal to 0.5%.

(Catalyst D: Co/EN/Sc/SiO2, 15%, And 0.2% Ru, 0.5% Of Sc.)

Comparative example 5. Catalyst E

This catalyst was prepared according to the method described in US - 4413064, example 1.

As a catalyst carrier using 100 g of gamma-alumina, harsh words (surface area = 175 m2/g; average pore size = 0.5 cm3/g; average particle diameter = 40-45 mm; purity 99%; specific gravity = 0,884 g/cm3), which annealed at 600oC for 2 hours in air flow.

Then prepare an aqueous solution of cobalt nitrate, dissolving to 87.1 g of Co(NO3)36H2O distilled water to a final volume of 100 cm3.

Using the method of initial absorption of moisture, the carrier is impregnated with this solution and after "cooking" for several hours, dried it in the oven for 16 hours at 120oC.

Then prepare 0.1 M solution of La(NO3)36H2O in ethanol and 0,00156 M solution of Ru(NO3)3in acetone. Take 7.2 cm3the first solution is diluted with ethanol to 33.5 cm3and 63.5 cm3the second solution to bringing the volume of acetone to 66.5 cm3. Both poured into a flask with a capacity of 250 cm3where 50 g of clicks is the number of solvent, equal to 2 cm3per gram of the carrier. The sample is dried on a rotary evaporator under vacuum at a bath temperature of approximately 35oC. To complete the removal of the solvent the sample is left in the furnace for 2 hours at 90oC.

Get product containing 15% (m/m), 0,2% (m/m) Ru, and 0.2% (m/m) La.

Collected in this way the sample is loaded into the reactor and restore H2(35 l/h) in accordance with the following temperature profile:

1. The temperature was adjusted from 25 to 100oC with a speed of 1oC/min and keep it at the level of the 100oC for 1 hour.

2. With the same speed, the temperature was raised to 200oC and at this level hold 2 hours.

3. Then the temperature is brought up to 360oC at a rate of 10oC/min and maintained at this level for 16 hours.

Next, the temperature is brought to 25oC, leaving the catalyst in a stream of nitrogen. Then the catalyst Passepartout a mixture of air (1.2 l/h) and nitrogen (60 l/h) for 16 hours.

Comparative example 6. Catalyst F

This catalyst was prepared by the method described in the patent US-4413064, example 1.

As a carrier for the catalyst used 25 g of silicon dioxide (with the same semimeasure.

Then prepare an aqueous solution of cobalt nitrate, dissolving to 21.77 grams of Co(NO3)26H2O distilled water to a volume of 45 cm3.

Using the method of initial saturation with moisture, the carrier is impregnated with this solution and after "cooking" for several hours, dried for 16 hours at 120oC in a furnace.

Then prepare 0.1 M solution of La(NO3)36H2O in ethanol and 0,00152 M solution of Ru(NO3)3in acetone. Take 5.5 cm3the first solution is diluted with ethanol to 25 cm3and 50 cm3the second solution. Both poured into a flask with a capacity of 250 cm3where is 38 g of the sample Co/SiO2, resulting in a gain ratio of acetone to ethanol, approximately equal to 2, and the amount of solvent equal to 2 cm3per gram of the carrier. The sample is dried on a rotary evaporator under vacuum at a bath temperature of approximately 35oC. To complete the removal of the solvent the sample is left in the furnace for 2 hours at 90oC.

The catalyst composition: 15% (m/m), 0,2% (m/m) Ru, and 0.2% (m/m) La.

Collected in this way the sample is loaded into the reactor and restore H2(27 l/h) in accordance with the following temperature profile is Uchenie 1 hour.

2. With the same speed, the temperature was raised to 200oC and at this level hold 2 hours.

3. The temperature was then brought to a final temperature of 360oC at a rate of 10oC/min and maintained at this level for 16 hours.

Next, the temperature is brought to 25oC, leaving the catalyst in a stream of nitrogen. Then the catalyst Passepartout a mixture of air (0,9 l/h) and nitrogen (45,6 l/h) for 16 hours.

From the comparison of the catalyst without the third element (comparative catalyst a) and the catalyst of the present invention (b, C, and D) it is obvious that a system with three elements are more active at lower temperatures, with values and selectivity if the25+more.

Activity of the catalysts according to the present invention exactly the same.

Comparing the catalyst E (applied on aluminium oxide) and the catalyst of the present invention, it can be seen that the catalyst E gives lower values and selectivity when receiving heavy hydrocarbons.

Finally, a comparative catalyst F (deposited on silicon dioxide as the catalyst of the present invention) shows a much greater reduction values and the election is of the catalyst for the conversion of synthesis gas, consisting mainly of inert carrier selected from at least one oxide of at least one element of Si, Ti, Al, Zr, Zn, Mg, SU and of the active components in the form of elements or oxides: more cobalt and fewer ruthenium and a third element selected from scandium and yttrium, the deposition of active components on the carrier, calcining, reduction, passivation, characterized in that it includes at least the following stages: (1) the first catalyst of the preceding product (A) containing cobalt and at least part of the inert carrier by deposition of cobalt on an inert carrier, followed by calcination, restoration and passivation inert carrier containing cobalt; (2) obtaining a second catalytic previous product (B) containing cobalt, ruthenium and at least part of the inert carrier by deposition of ruthenium on the first catalytic previous product (A) with subsequent annealing, recovery and passivation inert carrier containing cobalt and ruthenium; (3) the final catalyst by deposition of an element selected from scandium and yttrium, catalytic p is terasawa cobalt, ruthenium and the third element.

2. The method according to p. 1, wherein the inert carrier is a silicon dioxide.

3. The method according to p. 1, characterized in that in stage 1 cobalt are precipitated on the entire inert carrier.

4. The method according to p. 1, characterized in that in stage 1 the calcination is carried out at a temperature from 350 to 450oC, and at stages 2 and 3 at a temperature of from 250 to 350oC.

5. Composition for the preparation of the catalyst for the conversion of synthesis gas, characterized in that the method under item 1 and contains from 1 to 50 wt.% cobalt, 0.05 to 5 wt.% ruthenium and from 0.05 to 5 wt.% the third element selected from scandium and yttrium.

6. The composition according to p. 5, characterized in that it contains cobalt in an amount of 5 to 35%, ruthenium in an amount of from 0.1 to 3% and the third element in an amount of from 0.1 to 3 wt.%.

7. The catalyst for the conversion of synthesis gas consisting of inert carrier selected at least one oxide of at least one element selected from Si, Ti, Al, Zr, Zn, Mg, Sn, and of the active components in the form of elements or oxides, a larger amount of cobalt and a smaller number of ruthenium and a third element selected from scandium and yttrium, characterized in, would or would essentially unbranched saturated hydrocarbons from synthesis gas, mainly consisting of CO and H2in the presence of a catalyst, characterized in that the used catalyst under item 7 and the reaction of this mixture with the catalyst is carried out at pressures of 0.1 - 15 MPa, a temperature of 150 - 350oC, time flow rate 100 - 20000 volumes of synthesis gas to the volume of catalyst / h, when the molar ratio of H2/CO in the synthesis gas is in the range from 1:2 to 5:1.

9. The method according to p. 8, characterized in that provide a pressure of 1 to 10 MPa, the temperature 170-300oC hourly space velocity of 400 - 5000 volumes of synthesis gas to the volume of catalyst/h with a ratio of H2/CO in sites gas in the range from 1.2 : 1 to 2.5 : 1.

Priority points:

04.08.95 on PP.1,5.6,7,8;

11.04.96 on PP. 2,3,4,9.

 

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