Synthesis of framework modified ZSM-48 crystals
Methods are provided for synthesis ZSM-48 crystals (or other MRE framework crystals) having heteroatoms different from silicon and aluminum incorporated into the framework structure, and use of such crystals for applications such as catalytic processing of hydrocarbonaceous feeds. Examples of heteroatoms can include titanium, zirconium, and zinc.
1. A method of dewaxing a hydrocarbonaceous feedstock, comprising:
exposing a feedstock under effective dewaxing conditions to a catalyst comprising ZSM-48 crystals containing at least one of titania, zirconia, or zinc oxide as a framework metal oxide in a ZSM-48 structural framework, a molar ratio of SiO 2 to the framework metal oxide in the ZSM-48 structural framework being 70 to 200, a molar ratio of SiO 2 to Al 7 O 3 in the ZSM-48 structural framework of 120 to 225.
2. The method of claim 1 , wherein the ZSM-48 crystals are substantially free of intentionally added alumina.
3. The method of claim 1 , wherein the framework metal oxide is titania.
4. The method of claim 1 , wherein the effective dewaxing conditions comprise a temperature from 200° C. to 450° C., a pressure from 0 psig to 1000 psig 6.9 MPag), a WHSV from 0.2 hr −1 to 10 hr −1 , and a hydrogen/hydrocarbon mole ratio from 0.5 to 10.
5. The method of claim 1 , wherein the catalyst further comprises a metal oxide binder.
6. The method of claim 1 , wherein the catalyst further comprises a metal hydrogenation component.
7. The method of claim 6 , wherein the metal hydrogenation component comprises a group VIII metal, a Group VIB metal, or a combination thereof.
8. The method of claim 6 , wherein the metal hydrogenation component comprises 0.1 wt % to 1.5 wt % of Pt, Pd, or a combination thereof.
9. A method of synthesizing ZSM-48 crystals containing at least one of titania, zirconia, or zinc oxide as a framework metal oxide in a zeolite structural framework, the method comprising crystallizing a reaction mixture comprising a source of water, a source of SiO 2 , a source of the framework metal oxide, a source of an alkali metal M, and a source of a structure directing agent in the form of an organic cation, Q,
the reaction mixture having a molar ratio of structure directing agent cation, Q, to SiO 2 in said reaction mixture of 0.01 to 0.2; a molar ratio of SiO 2 to framework metal oxide in said reaction mixture of 50 to 225; a molar ratio of water to SiO 2 in said reaction mixture of 1 to 500; a molar ratio of hydroxyl group concentration to SiO 2 in said reaction mixture of from 0.1 to 0.5; a molar ratio of alkali metal, M, to SiO 2 in said reaction mixture of from 0.05 to 0.5; and a molar ratio of SiO 2 to Al 2 O 3 in said reaction mixture of 120 to 225.
10. The method of claim 9 , wherein the structure directing agent cation Q is a hexamethonium cation.
11. The method of claim 9 , wherein the reaction mixture is substantially free of a source of intentionally added Al 2 O 3 .
12. The method of claim 9 , wherein the reaction mixture further comprises seeds of ZSM-48 in an amount such that a weight percent of seeds relative to total weight of SiO 2 in said reaction mixture is between 0.1 wt % and 20 wt %.
13. The method of claim 9 , wherein the framework metal oxide is titania.