Fischer-tropsch process

Abstract

A process for the preparation of a composition comprising oxygenates and hydrocarbons by means of a Fischer-Tropsch synthesis reaction, said process comprising contacting a mixture of hydrogen, carbon monoxide, and carbon dioxide gases with a supported CoMn Fischer-Tropsch synthesis catalyst, wherein the supported synthesis catalyst comprises at least 2.5 wt % of manganese, on an elemental basis, based on the total weight of the supported synthesis catalyst; the weight ratio of manganese to cobalt, on an elemental basis, is 0.2 or greater; and, wherein carbon dioxide is present in the Fischer-Tropsch synthesis reaction is at least 5% v/v.

Claims

1. A process for the preparation of a composition comprising oxygenates and hydrocarbons by means of a Fischer-Tropsch synthesis reaction, said process comprising contacting a mixture of hydrogen, carbon monoxide, and carbon dioxide gases with a supported CoMn Fischer-Tropsch synthesis catalyst, wherein the supported synthesis catalyst comprises at least 2.5 wt % of manganese, on an elemental basis, based on the total weight of the supported synthesis catalyst; the weight ratio of manganese to cobalt, on an elemental basis, is 0.2 or greater; and, wherein the amount of carbon dioxide present in the Fischer-Tropsch synthesis reaction is at least 5% v/v.

2. A process according to claim 1, wherein, of the compounds in the composition comprising oxygenates and hydrocarbons having carbon chain length of eight carbon atoms or more, at least 30 wt. % are oxygenates.

3. A process according to claim 1, wherein at least 50 wt. % of the oxygenates in the composition comprising oxygenates and hydrocarbons are alcohols.

4. A process according to claim 1, wherein the amount of carbon dioxide present in the Fischer-Tropsch synthesis reaction is at least 10% v/v.

5. A process according to claim 1, wherein the amount of carbon dioxide present in the Fischer-Tropsch synthesis reaction is in the range of from 5% v/v to 25% v/v.

6. A process according to claim 1, wherein the support material of the supported CoMn Fischer-Tropsch synthesis catalyst comprises a material selected from titania, zinc oxide, zirconia, and ceria.

7. A process according to claim 1, wherein the support material comprises titania.

8. Process according to claim 7, wherein the support material is titania.

9. A process according to claim 1, wherein the weight ratio of manganese to cobalt present in the supported CoMn Fischer-Tropsch synthesis catalyst, on an elemental basis, is in the range of from 0.2 to 3.0.

10. A process according to claim 1, wherein the supported CoMn Fischer-Tropsch synthesis catalyst contains from 5 wt. % to 35 wt. % of cobalt, on an elemental basis, based on the total weight of the supported synthesis catalyst.

11. A process according to claim 1, wherein the supported CoMn Fischer-Tropsch synthesis catalyst contains from 2.5 wt. % to 15 wt. % of manganese, on an elemental basis, based on the total weight of the supported synthesis catalyst.

12. A process according to claim 1, wherein the combined amount of cobalt and manganese in the supported CoMn Fischer-Tropsch synthesis catalyst is less than 30 wt. %, on an elemental basis, based on the total weight of the supported synthesis catalyst.

13. A process according to claim 1, wherein the molar ratio of hydrogen to carbon monoxide is at least 1.

14. A process according to claim 1, wherein the Fischer-Tropsch synthesis reaction is conducted at a temperature of less than or equal to 300? C.

15. A process according to claim 1, wherein the Fischer-Tropsch synthesis reaction is conducted at a pressure in the range of from 1.0 to 10.0 MPa absolute.

16. A process according to claim 1, wherein the supported CoMn Fischer-Tropsch synthesis catalyst comprises less than 0.1 wt % of copper.

17. A process according to claim 1, wherein the composition comprising oxygenates and hydrocarbons comprises at least 1 wt % olefins.

18. A process according to claim 1, wherein the composition comprising oxygenates and hydrocarbons comprises linear alpha olefins.

19. A process according to claim 1, wherein the support material is titanic, and wherein the supported CoMn Fischer-Tropsch synthesis catalyst contains from 2.5 wt. % to 15 wt. % of manganese, on an elemental basis, based on the total weight of the supported synthesis catalyst, and wherein the weight ratio of manganese to cobalt present in the supported CoMn Fischer-Tropsch synthesis catalyst, on an elemental basis, is in the range of from 0.2 to 3.0.

20. A process for the preparation of a product composition comprising oxygenates and hydrocarbons via a Fischer-Tropsch synthesis reaction, said process comprising contacting a mixture of hydrogen, carbon monoxide, and carbon dioxide gases with a supported CoMn Fischer-Tropsch synthesis catalyst, to produce the product composition, wherein the supported synthesis catalyst comprises at least 2.5 wt % of manganese, on an elemental basis, based on the total weight of the supported synthesis catalyst; the weight ratio of manganese to cobalt, on an elemental basis, is 0.2 or greater; the amount of carbon dioxide present in the Fischer-Tropsch synthesis reaction is at least 5% v/v; and at least 30 wt. % of compounds in the product composition having a carbon chain length of eight carbon atoms or more are oxygenates; and at least 50 wt. % of the oxygenates of the product composition are alcohols.

21. A process according to claim 20, wherein the amount of carbon dioxide present in the Fischer-Tropsch synthesis reaction is at least 10% v/v.

Description

EXAMPLES

Example 1Catalyst Preparation

(1) An amount of Co(NO.sub.3).sub.2.6H.sub.2O and an amount of Mn(OAc).sub.2.4H.sub.2O were mixed in a solution with a small amount of water. This mixture was then added slowly to 100 g P25 TiO.sub.2 powder and mixed to obtain a homogeneous mixture. Co(NO.sub.3).sub.2.6H.sub.2O was used in an amount so as to give approximately 10 wt. % elemental Co on TiO.sub.2. The resultant paste/dough was extruded to form extrudate pellets and then dried and calcined at 300? C. Characterization was complete on the resulting catalysts using X-ray diffraction, H.sub.2 chemisorption, elemental analysis, temperature programmed reduction and BET surface area techniques.

(2) Several catalysts were made with between 55 and 62 g of cobalt hydrate hexahydrate, and between 0 and 55 g of manganese acetate tetrahydrate to give different manganese loadings and different Mn:Co ratios as detailed in Table 1.

(3) TABLE-US-00001 TABLE 1 Mass of Mass of cobalt manganese nitrate Cobalt acetate Manganese hexahydrate loading tetrahydrate Loading Mn/Co (g) (wt. %) (g) (wt. %) ratio 62 10 55 10 1.00 60 10 40 7.5 0.75 58 10 25 5 0.50 57 10 16.2 3 0.30 56 10 10.8 2 0.20 56 10 7.6 1.5 0.15 56 10 5.4 1 0.10 55 10 0 0 0.00

Example 2General Procedure for Fischer-Tropsch Synthesis

(4) 1 ml samples of catalyst in the form of extrudates (1.25-3.5 mm) were loaded into a high throughput parallel reactor and reduced under a H.sub.2 stream (15 h, at 300? C., 100% H.sub.2, atmospheric pressure). The gaseous supply was switched to a mixture of hydrogen and carbon monoxide (H.sub.2/C.sub.0=1.8), additionally comprising 10% v/v nitrogen and 8% v/v carbon dioxide, the pressure was maintained at 4.3 MPa absolute, and a GHSV of 1500 hr-1. The temperature was raised to achieve conversion of 55-65% based on CO, and maintained throughout the Fischer-Tropsch reaction. On line analytics were completed by GC. Results are presented in Tables 2 and 3 below.

(5) TABLE-US-00002 TABLE 2 10% 1% Mn/10% 5% Mn/10% Selectivity % Co/TiO.sub.2 Co/TiO.sub.2 Co/TiO.sub.2 Methanol 0.25 0.27 0.7 Ethanol 0.00 0 0.06 Propanol 0.07 0.15 0.83 Butanol 0.00 0 2.73 Pentanol 0.08 0.19 2.42 Hexanol 0.06 0.16 1.97 Heptanol 0.06 0.14 1.57 Octanol 0.05 0.13 1.21 Nonanol 0.05 0.12 0.96 Decanol 0.05 0.1 0.75 CO.sub.2 conversion (%) 10.90 24.60 26.1 Applied Temperature (C) 198 197 203 Total OH selectivity (%) 0.70 1.60 14.8 Total Olefin selectivity (%) 4.2 5.6 20.9

(6) The results presented in Table 2 shows that the 10% Co/5% Mn/TiO.sub.2 catalyst has approximately a 20-30 fold increase in alcohols over the non-manganese catalyst.

(7) TABLE-US-00003 TABLE 3 0% Mn/10% 1% Mn/10% 5% Mn/10% Molar rate: Co/TiO.sub.2 Co/TiO.sub.2 Co/TiO.sub.2 RM_(Methanol) [mol/h] 2.271E?05 2.537E?05 6.119E?05 RM_(Ethanol) [mol/h] 0 0 2.846E?06 RM_(Propanol) [mol/h] 2.272E?06 4.719E?06 2.43E?05 RM_(Butanol) [mol/h] 1.754E?06 4.384E?06 5.879E?05 RM_(1-Pentanol) [mol/h] 1.558E?06 3.604E?06 4.159E?05 RM_(1-Hexanol) [mol/h] 9.817E?07 2.747E?06 2.896E?05 RM_(1-Heptanol) [mol/h] 7.563E?07 2.004E?06 2.005E?05 RM_(1-Octanol) [mol/h] 6.144E?07 1.537E?06 1.322E?05 RM_(1-Nonanol) [mol/h] 5.237E?07 1.253E?06 8.78E?06 RM_(1-Decanol) [mol/h] 3.595E?07 9.917E?07 6.438E?06 RM_(1-Undecanol) [mol/h] 2.829E?07 6.378E?07 4.4E?06 RM_(1-Dodecanol) [mol/h] 2.753E?07 4.78E?07 2.811E?06 RM_(1-Tridecanol) [mol/h] 0.0 3.209E?07 1.946E?06 RM_(1-Tetradecanol) [mol/h] 0 0 1.154E?06

(8) Table 3 shows the molar rates of products produced under the CO.sub.2-containing feed, in particularly for the longer-chain linear alcohols