Catalyst and its use in fatty acid isomerisation
The present invention relates to an isomerisation catalyst, in particular a zeolite catalyst. There is provided a method for making a particularly preferred zeolite catalyst by means of modifying catalytic zeolite materials. There is also provided a 5 process for isomerising fatty acids or alkyl esters thereof to produce branched fatty acids employing such an isomerisation catalyst, a composition comprising branched fatty acids, and also use of the isomerisation catalyst.
1. A method of producing branched fatty acids, comprising:
contacting a starting material comprising unsaturated fatty acids with an isomerization catalyst comprising
an activity factor of from 30,000 to 200,000, wherein the activity factor is calculated as shown in formula (I):
activity factor=S external ×strong NH 3 uptake (I)
wherein:
“S external ” is the external surface area in m 2 /g of the catalyst, measured by nitrogen physisorption; and
“strong NH 3 uptake” is the amount of NH 3 in μmol/g which desorbs from the catalyst at a temperature between 327° ° C. and 550° C. during ammonia temperature programmed desorption; and
isomerizing, with the catalyst, an amount of the unsaturated fatty acids to form a composition comprising branched fatty acids;
wherein the catalyst is a zeolite comprising micropores and mesopores and wherein the micropore volume (V micro ) is from 1% to 50% of the total pore volume (V pore ) of micropores and mesopores, and wherein the catalyst has a surface area (S total ) of 450 m 2 /g to 650 m 2 /g as measured via BET.
2. The method of claim 1 , wherein the catalyst is used at a concentration of 0.1 to 2.8 wt %, based on the total weight of fatty acids in the starting material.
3. The method of claim 1 , wherein the micropore volume (V micro ) is from 8% to 25% of the total pore volume (V pore ) of micropores and mesopores.
4. The method of claim 1 , wherein the contacting of the starting material with the isomerization catalyst comprises contacting a feedstock comprising unsaturated fatty acids with the isomerization catalyst.
5. The method of claim 1 , wherein said catalyst is a zeolite of the MFI type framework.
6. The method of claim 1 , wherein said catalyst is a zeolite and comprises channels with 10 member ring structures.
7. The method of claim 1 , wherein said catalyst is a ZSM-5 zeolite.
8. The method of claim 1 , wherein the catalyst-external surface area S external of the catalyst is at least 80 m 2 /g.
9. The method of claim 1 , wherein the catalyst has-strong NH 3 uptake of the catalyst is at least 100 μmol/g.
10. The method of claim 1 , wherein the catalyst has a silica to alumina molar ratio (SAR) of at least 15.
11. The method of claim 1 , wherein the zeolite is obtainable by a method of modifying the structure of a zeolite comprising:
contacting the zeolite with an alkaline solution;
contacting the zeolite with an acidic solution; and
contacting the zeolite with an ion exchange material.
12. The method of claim 11 , wherein the ion exchange material is an ion exchange solution comprising NH 4 NO 3 .
13. The method of claim 11 , wherein the alkaline solution and/or the acidic solution and/or the ion exchange solution is at a concentration of under 1 M.
14. The method of claim 11 , wherein the method of modifying the structure of the zeolite further comprises:
calcining the zeolite at a temperature of at least 400° C. for at least 2 hours.
15. The method of claim 1 , wherein the catalyst has a silica to alumina molar ratio of 15:1 to 100:1.
16. The method of claim 1 , wherein the catalyst has a surface area (S total ) of 500 m 2 /g to 600 m 2 /g.
17. The method of claim 1 , wherein the external surface area (S external ) of the catalyst is 160 m 2 /g to 400 m 2 /g.
18. The method of claim 1 , wherein the catalyst has a strong NH 3 uptake of 250 μmol/g to 600 μmol/g.
19. The method of claim 1 , wherein the activity factor is 80,000 to 140,000.