JPS631297B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing hydrocarbons by a catalytic reaction between carbon monoxide and hydrogen. The production of hydrocarbons from a mixture of carbon monoxide and hydrogen by contacting this mixture with a catalyst at elevated temperature and pressure is described in the literature as Fischer-Tropsch hydrocarbon synthesis.
The behavior of a catalyst for Fischer-Tropsch synthesis can be judged based on the conversion and selectivity that can be achieved with and with respect to space velocity with the catalyst. The term conversion refers in this context to the mole percentage of the gas mixture that is converted to hydrocarbons, and the term selectivity refers to the weight percentage of _C3 ⁺ hydrocarbons produced based on the total amount of hydrocarbons produced. You should think about it. In general, a good catalyst for Fischier-Tropsch hydrocarbon synthesis will convert at least 50% m of the gas mixture with a selectivity of at least 70% w at a space velocity of at least 400 Nl l ^-1 h ^-1 It can be stated that the requirement that it must be possible is met. Catalysts are judged to be better suited for this purpose as higher conversions and selectivities can be achieved and as higher space velocities can be used. Some of the catalysts proposed in the literature for use in Fischier-Tropsch hydrocarbon synthesis have H ₂ /CO molar ratios of at least 1.0.
When applied to a mixture of carbon monoxide and hydrogen, there are several methods that meet the above three requirements. However, when applying these catalysts to mixtures of carbon monoxide and hydrogen with a H ₂ /CO molar ratio less than 1.0, it is found that in most cases it is not possible to simultaneously meet all three minimum requirements mentioned above. I found this out through research. In general, when applying the catalyst to low hydrogen gas mixtures, two of the minimum requirements can be easily met, but the third parameter, which is important in this connection, then has an unacceptably low value. have at any temperature by contacting a low hydrogen gas mixture with a catalyst that meets certain minimum requirements regarding the behavior of the catalyst in the Fischier-Tropsch reaction.
The conversion rate that can be achieved at pressure and space velocity is
This catalyst was used in the well-known CO-conversion reaction (CO+H ₂ O→
It has been found that the behavior of the catalyst in CO ₂ +H ₂ ) can be significantly enhanced by use in combination with catalysts that meet certain minimum requirements. For one catalyst of the combination, the catalyst is capable of converting at least 30% of a low hydrogen gas mixture with a selectivity of at least 70% at any temperature, pressure, and space velocity. Hold that it must be. With respect to the other catalysts in the combination, the catalysts:
at any temperature and pressure and
At a space velocity of 1000Nl・l ^-1・h ^-1 , 10.0
It is maintained that it must be possible to convert at least 80% m of the water present in the mixture of carbon monoxide and water with a CO/H ₂ O molar ratio into hydrogen. As far as the mixing ratio of the catalysts is concerned, at least 10%v of each catalyst should be present in the catalyst combination. In the above formulation, the combination of catalysts that meets the criteria for the Fischer-Tropsch reaction is
It was of course considered that the criteria would not be met for CO-conversion reactions and vice versa. This is consistent with practical practice, where the catalysts recommended for the Fischier-Tropsch reaction generally exhibit no or little activity toward the CO-conversion reaction, and vice versa. In the research on the present subject, the principle on which the invention is based, namely a highly suitable catalyst for the production of hydrocarbons from low-hydrogen gas mixtures, combines a catalyst with Fischer-Tropsch activity and a catalyst with CO-conversion activity. The fact that this can be obtained can also be exploited in another manner, namely by using one catalyst that combines these two functions. Such catalysts can be prepared, for example, by fixing both one or more metals with Fischer-Tropsch activity and one or more metals with CO-converting activity onto an inert support by impregnation. can be manufactured. Therefore, the present invention provides a method for producing hydrocarbons by a catalytic reaction between carbon monoxide and hydrogen _.
A mixture of carbon monoxide and hydrogen having a molar ratio of less than 1.0 is brought into contact with two catalysts at elevated temperature and pressure, such that one of the two catalysts is
The other catalyst is a CO-conversion catalyst containing at least one of the metals iron, cobalt, nickel and ruthenium or a compound thereof, and the other catalyst is a CO-conversion catalyst containing at least one of the metals chromium, copper, zinc and molybdenum. species or compounds thereof, and at least 10% of each of said catalysts.
The present invention relates to a process for producing hydrocarbons, characterized in that V is present in the catalyst combination thereof. In the process according to the invention, a combination of two catalysts is used, for convenience designated as catalysts X and Y. The two catalysts may be present as a mixture, in principle each particle of catalyst X being surrounded by a particle of catalyst Y and vice versa. When the process is carried out with a fixed catalyst bed, this bed may be composed of alternating layers of catalyst X and catalyst Y particles. 2
If the seed catalysts are used as a mixture, this mixture can be a macromixture or a micromixture.
In the first case, the combination consists of two types of macroparticles, one of which consists entirely of catalyst X and the other entirely of catalyst Y. In the second case, the combination consists of one type of macroparticle,
Each macroparticle is made up of multiple microparticles of both Catalyst X and Catalyst Y. The catalyst combination according to the invention in the form of a micromixture can be further prepared, for example, by thoroughly mixing finely divided powders of catalyst X and finely divided catalyst Y and by extruding or pelletizing the mixture. It can be manufactured by shaping into large particles. In the process according to the invention it is preferred to use the catalyst combination in the form of a micromixture. The process according to the invention is preferably carried out at a temperature of 200 to 350° C., a pressure of 10 to 70 bar and a space velocity of 400 to 5000, in particular 400 to 2500 Nl.l ^-1 .
It is done at h ^-1 . In the process, one of the catalysts in the combination converts H ₂ /CO with a selectivity of at least 70%w at the temperature, pressure and space velocity at which the process is carried out.
It should be possible to convert at least 30% m of the mixture. Catalysts with this property are in the group of catalysts that are known and described in the literature as Fischer-Tropsch catalysts. Such catalysts often include one or more metals from the iron group or ruthenium together with one or more promoters to increase activity and/or selectivity and sometimes a support material such as diatomaceous earth. do. By precipitation, by melting,
Or it can be produced by impregnation. The production of catalysts containing one or more metals from the iron group by impregnation involves impregnating a porous support with an aqueous solution of one or more salts of metals from the iron group and, if necessary, a promoter. This is accomplished by drying and firing the composition. In the process according to the invention, preference is given to using catalyst combinations in which the catalyst having the required Fischer tropism activity is an iron or cobalt catalyst, in particular such a catalyst prepared by impregnation. A very suitable Fischer-Tropsch catalyst for use in the catalyst combination according to the invention is a catalyst prepared by impregnation according to Dutch Patent Application No. 7612460. The catalyst is
10 to 75 pbw of one or more metals from the iron group per 100 pbw of support, together with one or more promoters in an amount of 1 to 50% of the amount of metal from the iron group present on the catalyst. and the catalyst has a specific mean pore diameter (p) of at most 10,000 nm and a specific mean particle diameter (d) of at most 5 mm, with a quotient p/d greater than 2 (p in nm and d in mm). Have it so that it becomes. If in the process according to the invention it is intended to use a catalyst combination in which the catalyst with Fischer-Tropsch activity is an iron catalyst, alkali metals,
Iron catalysts containing a promoter combination consisting of a metal that readily undergoes ring formation, such as copper or silver, and optionally a metal that is difficult to reduce, such as aluminum or zinc, are preferred. Iron catalysts which are very suitable for this purpose are catalysts containing iron, potassium and copper prepared by impregnation on silica as a support. If an iron catalyst is used in the catalyst combination as catalyst having the required Fisher-Tropsch activity, the process according to the invention is preferably carried out at a temperature of 250 DEG to 325 DEG C. and a pressure of 25 to 50 bar. In the method according to the invention, the required
If it is intended to use a catalyst combination in which the catalyst with tropsch activity is a cobalt catalyst, cobalt catalysts containing an alkaline earth metal and a promoter combination consisting of thorium, uranium, or cerium are preferred. A very suitable cobalt catalyst for this purpose is
Cobalt, magnesium, produced by impregnation
and a catalyst containing thorium on silica as a carrier. Other very suitable cobalt catalysts produced by impregnation are catalysts which contain, in addition to cobalt, one of the elements chromium, titanium, zirconium and zinc on silica as a support. If a cobalt catalyst is used in the catalyst combination as catalyst with the required Fischer-Tropsch activity, the process according to the invention preferably
It is carried out at a temperature of 220 to 300°C and a pressure of 10 to 35 bar. In the process according to the invention, one of the catalysts in the combination is at the temperature and pressure at which the process is carried out and
At a space velocity of 1000Nl・l ⁺¹・h ^-1 , CO/
It should be possible to convert at least 80% m of the water present in a mixture of carbon monoxide and water with a H ₂ O molar ratio of 10.0 into hydrogen. Catalysts with this property are known and are in the group of catalysts described in the literature as CO-conversion catalysts. Such catalysts include as catalytically active component one or more metals selected from the group consisting of chromium, copper, zinc, and molybdenum, either as such or in the form of their oxides or sulfides. Appropriate CO−
An example of a conversion catalyst is found in Dutch Patent Application No. 7305340
7304793 and a spinel catalyst according to French Patent Application No. 7633900. In the method according to the invention, the required
Preference is given to using catalyst combinations in which the catalyst having CO-conversion activity is a catalyst containing both copper and zinc, in particular a catalyst with a Cu/Zn atomic ratio of 0.25 to 4.0. In the process, the starting material should be a mixture of carbon monoxide and hydrogen with a H ₂ /CO molar ratio less than 1.0. Such mixtures can very suitably be produced by partial combustion of carbon- and hydrogen-containing substances, especially substances with a low hydrogen content. Examples of these materials are lignite, anthracite, and coke. During the partial combustion, the feed is converted in finely divided form with oxygen or air, if desired with oxygen-enriched air, to form a gas mixture containing, inter alia, hydrogen, carbon monoxide, carbon dioxide, nitrogen and water. become. In the combustion, water vapor is preferably used as a temperature regulating agent.
The partial combustion is preferably performed at a temperature of 900 to 1500°C.
and at a pressure of 10 to 50 bar. Purification of the crude gas mixture, in which ash, carbon-containing substances, hydrogen sulfide and carbon dioxide are removed, yields a gas consisting essentially of a mixture of carbon monoxide and hydrogen. In the process according to the invention, the starting material is preferably a gas mixture with a H ₂ /CO molar ratio greater than 0.4. If gas mixtures with a H ₂ /CO molar ratio of less than 0.4 are used, this molar ratio is preferably increased to a value of 0.4 to 1.0 before applying the method according to the invention to these gas mixtures. Pre-increasing the H ₂ /CO molar ratio of the gas mixture is very suitably carried out by adding hydrogen or by subjecting the gas mixture to the known CO conversion reaction. can be done. If the starting materials are gas mixtures with a H ₂ /CO molar ratio of less than 0.4, attractive results can also be obtained by applying the process according to the invention to such mixtures with addition of water. H ₂ /CO molar ratio is 0.8 or more
1.0, it is preferred in the process according to the invention to use a catalyst combination in which the catalyst having the required Fischer tropism activity is a cobalt catalyst. In the process according to the invention, at least 10%v of each of the catalysts should be present in the catalyst combination. The proportions in which the two catalysts should be present in the catalyst combination vary and depend, inter alia, on the intended conversion and selectivity, the composition of the gas mixture, the reaction conditions used, and the activity of the two catalysts in the combination. Depends on. Thus, the reduction in conversion that occurs when the H ₂ /CO molar ratio of the feed gas is reduced under certain reaction conditions can be compensated for by using a catalyst with higher CO-conversion activity in the combination. can be done. The increase in selectivity is due to the combination of more selective Fischer-Tropsch catalysts (e.g. catalysts with a higher content of selectivity promoter).
This can be achieved by using Increased conversion can be achieved by using a more active Fischer-tropsch and CO-conversion catalyst in the combination (eg, a catalyst with a higher content of catalytically active metal). The process according to the invention can very suitably be carried out by passing the feed upwardly or downwardly through a vertically arranged reactor in which a fixed or moving bed of catalyst combination is present. The process can be carried out, for example, by using gas velocities such that the catalyst bed expands through the feed upwardly into a vertically arranged catalyst bed. If desired, the process can also be carried out using suspension of the catalyst combination in a hydrocarbon oil. 1 to 5 mm, 0.5 to 2.5 mm, respectively, depending on whether the process is carried out using a fixed catalyst bed, an expanded catalyst bed or a catalyst suspension.
and catalyst particles having a diameter of 20 to 150 microns are preferred. When the process is carried out using a fixed catalyst bed, deposition of waxy hydrocarbons occurs on the catalyst combination, resulting in a decrease in activity. This deactivation is
This can be effectively prevented by continuously washing the catalyst combination with a fraction of the product produced in the process. For this purpose, fractions with an initial boiling point above 200°C and a final boiling point below 550°C are preferred. An additional advantage of the continuous cleaning of the catalyst combination is that temperature control of the process, which is highly exothermic, is simplified. In addition to hydrocarbons and oxygen-containing hydrocarbons with a wide range of molar weights, the reaction products leaving the reactor in the process according to the invention include, inter alia, water, nitrogen, carbon dioxide, and unconverted carbon monoxide, and hydrogen. Contains. If the method is performed in a single pass, C ₃ ⁺
- A fraction is separated from the reaction product as the final product. When the process is carried out in a recirculating operation, C ₃ ⁺ −
The fraction is also separated from the reaction product as the final product, but the remainder of the reaction product is separated from the reaction product, if necessary after reduction of the carbon dioxide content and, inter alia, using a bleed stream to avoid nitrogen accumulation. Recirculated to the reactor. The invention is further illustrated in the following examples. EXAMPLE Six (-) six catalyst combinations were prepared according to the present invention. A Fischer-Tropsch catalyst selected from catalysts 1 to 4 and a CO selected from catalysts A to C.
The catalyst combination was obtained by mixing with the conversion catalyst in a volume ratio of 1:1. Fisher-Tropsch Catalyst 5 and CO-Conversion Catalyst A both 44
Grind to a powder with a diameter of particle size smaller than microns, mix the powder in a volume ratio of 1:1, and pelletize the mixture into larger particles, then grind and sieve to a powder with a diameter of
The catalyst combination was obtained by converting to granules with 1.7 to 2.8 mm. In order to be able to obtain correct conclusions about the behavior of the catalyst combination in hydrocarbon synthesis according to the Fischer-Tropsch, a sixth Fischer-Tropsch catalyst was included in the investigation (catalyst 6). Catalysts 1-6 and A-C had the following compositions. Catalyst 1 Fe/Cu/K/containing 25 pbw iron, 1.25 pbw copper, and 1 pbw potassium per 100 pbw silica.
_SiO2 catalyst. Particle diameter: 1.0-2.4mm. Catalyst 2 Fe/Cu/K/containing 25 pbw iron, 1.25 pbw copper, and 2 pbw potassium per 100 pbw silica.
_SiO2 catalyst. Particle diameter: 1.7-2.8mm. Catalyst 3 25 pbw cobalt, 1.04 pbw thorium, and
Co/Th/Mg/SiO ₂ catalyst containing 1.18 pbw magnesium per 100 pbw silica. Particle size: 1.7-2.8mm. Catalyst 4 25pbw cobalt and 1pbw chromium on silica
Co/Cr/ _SiO2 catalyst contained per 100pbw. Particle size: 1.7-2.8mm. Catalyst 5 25pbw iron and 2pbw potassium with 100pbw silica
Fe/K/SiO ₂ catalyst was included. Particle size: 1.7-2.8mm. Catalyst 6 25pbw iron and 2pbw potassium with 200pbw silica
Fe/K/SiO ₂ catalyst was included. The catalyst 6 is
Catalyst 5 and silica are ground to a powder with a particle size of less than 44 microns, the powders are mixed in a volume ratio corresponding to the above composition, the mixture is pelletized into large particles, and then milled and sieved to a diameter of 1.7 microns. obtained by converting into granules having a diameter of 2.8 mm to 2.8 mm. Catalyst A Cu/Zn/SiO ₂ catalyst containing 15 pbw copper and 30 pbw zinc per 100 pbw silica. Particle size: 1.0-3.4mm. Catalyst B 53.8pbw copper and 18.1pbw aluminum with zinc
Cu/Al/Zn catalyst included per 100pbw. Particle size: 1.7-2.8mm. Catalyst C 225pbw copper and 105pbw aluminum with zinc
Cu/Al/Zn catalyst included per 100pbw. Particle size: 1.7-2.8mm. Catalyst combinations ~ and catalysts 1-6 and A
~C according to the Fisher-Tropsch by contacting a mixture of carbon monoxide and hydrogen with a H ₂ /CO molar ratio of 0.5 with each of these catalyst combinations and catalysts at 280° C. and 30 bar. Tested for hydrocarbon synthesis. In addition, the behavior of catalysts 1 to 6 and A to C regarding the CO-conversion reaction is
A mixture of carbon monoxide and water with a CO/H ₂ O molar ratio of 10.0 was heated at 280 °C, 30 bar, and a space velocity.
It was investigated by contacting each of these catalysts at 1000 Nl·l ⁻¹ ·h ⁻¹ . The results of these experiments and the space velocities used for the Fischer-Tropsch reactions are shown in the table.

【table】

[Table] There is no exchange.

Claims (1)

[Claims] 1. In a method for producing hydrocarbons by a catalytic reaction between carbon monoxide and hydrogen, a mixture of carbon monoxide and hydrogen having a H ₂ /CO molar ratio of less than 1.0 is heated with two types of catalysts. The two catalysts are brought into contact at elevated pressure, such that one of the two catalysts is a Fischer-Tropsch catalyst and contains at least one of the metals iron, cobalt, nickel and ruthenium, or a compound thereof, and the other catalyst is Chromium is a CO-conversion catalyst,
Process for the production of hydrocarbons, characterized in that they contain at least one of the metals copper, zinc and molybdenum or a compound thereof, and that at least 10%v of each of said catalysts is present in the catalyst combination. . 2. A catalyst combination according to claim 1, characterized in that a catalyst combination consisting of one type of macroparticle is used, each macroparticle consisting of a number of microparticles of each of two types of catalyst. Method. 3. Process according to claim 1 or 2, characterized in that it is carried out at a temperature of 200 to 350°C, a pressure of 10 to 70 bar and a space velocity of 400 to 5000 Nl·l ^-1 ·h ^-1 . 4. Process according to claim 1, characterized in that the catalyst having Fischer-Tropsch activity is an iron or cobalt catalyst and a catalyst combination prepared by impregnation is used. 5. the catalyst comprises 10 to 75 pbw of iron or cobalt per 100 pbw of support, together with one or more promoters in an amount of 1 to 50% of the amount of iron or cobalt present on the catalyst; There are many
Specific mean pore diameter (p) of 10000 nm and at most 5
5. Process according to claim 4, characterized in that it has a specific mean particle diameter (d) in mm such that the quotient p/d is greater than 2 (p in nm and d in mm). 6. Claim 4 or 5, characterized in that the catalyst is an iron catalyst containing a promoter combination consisting of an alkali metal and copper or silver.
The method described in section. 7. Process according to any one of claims 4 to 6, characterized in that the process is carried out at a temperature of 250 to 325°C and a pressure of 20 to 50 bar. 8 the catalyst comprises an alkaline earth metal and thorium;
6. Process according to claim 4, characterized in that it is a cobalt catalyst containing a promoter combination consisting of uranium or cerium. 9. The catalyst, in addition to cobalt, contains elemental chromium,
The method according to claim 4 or 5, characterized in that the catalyst contains one of titanium, zirconium and zinc on silica as a carrier. 10. Any of claims 4, 8 and 9, characterized in that the catalyst is a cobalt catalyst and the process is carried out at a temperature of 220 to 300°C and a pressure of 10 to 35 bar. The method described in paragraph 1. 11 the catalyst is a cobalt catalyst and the method
11. The method according to claim 4 and any one of claims 8 to 10, characterized in that it is applied to a feed gas whose _H2 /CO molar ratio is between 0.8 and 1.0. 12. Process according to any one of claims 1 to 11, characterized in that a catalyst combination is used in which the catalyst with 12 CO-conversion activity is a catalyst with both copper and zinc. 13. Process according to any one of claims 1 to 12, characterized in that the _H2 /CO molar ratio of the feed gas is greater than 0.4. 14. Claims characterized in that they are carried out with fixed catalyst beds, expanded catalyst beds, or catalyst suspensions, and with catalyst particles having diameters of 1 to 5 mm, 0.5 to 2.5 mm, and 20 to 150 microns, respectively. The method according to any one of items 1 to 13. 15. Any one of claims 1 to 14 characterized in that it is carried out using a fixed bed catalyst bed and that the catalyst combination is washed continuously with a fraction of the product produced by the process. The method described in paragraph 1.