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 Co—Mn 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 Co—Mn 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. % of which are oxygenates.

3. A process according to claim 1, wherein the 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 Co—Mn 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. A 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 Co—Mn 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 Co—Mn 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 Co—Mn 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 Co—Mn 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. (canceled)

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

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

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

20. A process according to claim 1, wherein the support material is titania, and wherein the supported Co—Mn 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 Co—Mn Fischer-Tropsch synthesis catalyst, on an elemental basis, is in the range of from 0.2 to 3.0.

Description

EXAMPLES

Example 1—Catalyst Preparation

[0083] 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.

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.

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 2—General Procedure for Fischer-Tropsch Synthesis

[0084] 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.

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 

[0085] 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.

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

[0086] Table 3 shows the molar rates of products produced under the CO.sub.2-containing feed, in particularly for the longer-chain linear alcohols