Hydroisomerization catalysts based on Fe containing molecular sieves
The hydroisomerization of a paraffinic hydrocarbon feedstock obtained from renewable sources is effectively achieved by passing the feedstock in the presence of hydrogen over a hydroisomerization catalyst comprising a crystalline metal silicate molecular sieve, in which a portion of the crystalline framework contains iron.
1. A process for hydroisomerization of a paraffinic hydrocarbon feedstream, the process comprising:
contacting said hydrocarbon feedstream with hydrogen and a catalyst comprising a crystalline metal silicate molecular sieve having a crystalline framework, wherein the crystalline framework comprises aluminum located at aluminum sites, wherein at least a portion of the aluminum sites are isomorphously-substituted with iron, and yielding a product having an increase in branched hydrocarbons relative to said hydrocarbon feedstream,
wherein the metal silicate molecular sieve is ZSM-12, ZSM-22, ZSM-23, ZSM-48, ZSM-57, or MCM-22,
wherein the catalyst further contains from 0.01 to 10 wt. % of a platinum group metal and
wherein said metal silicate molecular sieve has a molar framework formula [X a X 1 1-a ] 2 O 3 :(y)YO 2 wherein X is iron, X 1 is aluminum, a is at least 0.90; Y is silicon; and y is from about 20 to about 300.
2. The process of claim 1 , wherein said molecular sieve has a pore size of about 3 to 10 angstroms.
3. The process of claim 1 , wherein said platinum group metal is platinum.
4. The process of claim 1 , wherein said paraffinic hydrocarbon feedstream comprises nC 8+ hydrocarbons.
5. The process of claim 4 , wherein said paraffinic hydrocarbon feedstream is obtained from the deoxygenation of a non-petroleum feedstock originating from one of plants or animals.
6. The process of claim 5 , wherein said non-petroleum feedstock comprises glycerides and free fatty acids.
7. The process of claim 6 , wherein said non-petroleum feedstock comprises palm oil.
8. The process of claim 1 , wherein said molecular sieve in as synthesized form has a formula on an anhydrous basis of
(0.05 to 1.0)M 2 O:(0 to 75)R:Z 2 O 3 :( y )YO 2
wherein M is an alkali metal cation, R is a specific organic directing agent and Z is a mixture of X and X′.
9. The process of claim 1 , wherein said product has a cloud point ranging from 0 to −65° C.
10. The process of claim 9 , wherein said product is a diesel fuel having a cloud point ranging from −10 to −50° C.
11. The process of claim 9 , wherein said product is a biojet fuel having a cloud point ranging from −25 to −65° C.
12. The process of claim 1 , wherein said catalyst is not treated with a passivator.
13. The process of claim 1 , wherein said catalyst further contains a base metal promoter.
14. The process of claim 13 , wherein said base metal promoter is nickel.
15. The process of claim 1 , wherein a majority of said platinum group metal is contained on said molecular sieve and said catalyst is mixed with a matrix material.