Methods for synthesizing hierarchical zeolites for catalytic cracking
Provided here are zirconium-substituted hierarchical zeolite compositions and methods of preparing such catalytic compositions. One such method involves subjecting the zirconium-substituted zeolite to a framework modification process using a single template to produce a framework-modified zeolite, followed by subjecting the framework-modified zeolite to an ion exchange process to produce a hierarchical zeolite composition. Also provided are methods of catalytic cracking of hydrocarbon feedstocks using these zirconium-substituted hierarchical zeolite compositions.
1. A method of catalytic cracking of a hydrocarbon-containing feedstock to catalytic cracking conversion products, the method comprising:
providing, to a catalytic cracking process, a hierarchical zeolite composition prepared by:
subjecting an initial zeolite and a zirconium source to a partial isomorphous substitution process to produce a zirconium-substituted zeolite;
subjecting the zirconium-substituted zeolite to a framework modification process using a single template to produce a framework-modified zeolite; and
subjecting the framework-modified zeolite to an ion exchange process to produce a hierarchical pore structure in at least a portion of the framework-modified zeolite, resulting in the hierarchical zeolite composition; and
contacting a hydrocarbon-containing feedstock with the hierarchical zeolite composition at catalytic cracking conditions to produce catalytic cracking conversion products.
2. The method of claim 1 , wherein the initial zeolite is one or more of ZSM-5, ZSM-11, ZSM-12, ZSM-23, ZSM-35, ZSM-38 and ZSM-48.
3. The method of claim 1 , wherein the zirconium source is one or more of zirconium chloride, zirconium sulfate, zirconium nitrate, and zirconium oxide.
4. The method of claim 1 , wherein the zirconium source is zirconium chloride and the initial zeolite is ZSM-5.
5. The method of claim 1 , wherein the single template is a tetra-ammonium salt or hydroxide.
6. The method of claim 1 , wherein the framework modification process comprises:
contacting the zirconium-substituted zeolite with tetrapropylammonium hydroxide (TPAOH) to produce a TPAOH-treated zeolite;
subjecting the TPAOH-treated zeolite to hydrothermal aging; and
calcining at least a portion of TPAOH-treated zeolite to produce the framework-modified zeolite.
7. The method of claim 1 , wherein the ion exchange process comprises:
contacting the framework-modified zeolite with an acid to produce a hierarchical pore structure in at least a portion of the framework-modified zeolite, resulting in the hierarchical zeolite composition.
8. The method of claim 1 , wherein the ion exchange process comprises:
contacting the framework-modified zeolite with ammonium chloride to produce a hierarchical pore structure in at least a portion of the framework-modified zeolite, resulting in the hierarchical zeolite composition.
9. The method of claim 1 , wherein preparing the hierarchical zeolite composition further includes:
calcining at least a portion of hierarchical zeolite composition and contacting the hierarchical zeolite composition with steam, before contacting the hierarchical zeolite composition with the hydrocarbon-containing feedstock.
10. The method of claim 1 , wherein preparing the hierarchical zeolite composition further includes:
impregnating at least a portion of hierarchical zeolite composition with one or more of phosphorous, lanthanum, and manganese.
11. The method of claim 1 , wherein said catalytic cracking conversion products include olefins having 2 to 4 carbon atoms and yield of said olefins is increased by at least ten percent as compared to yield of said olefins from a catalytic cracking process using the initial zeolite.
12. The method of claim 1 , wherein said catalytic cracking conversion products include olefins having 2 to 4 carbon atoms and yield of said olefins is increased by at least twenty percent as compared to yield of said olefins from a catalytic cracking process using the initial zeolite.
13. The method of claim 1 , wherein said catalytic cracking conversion products include gasoline and yield of the gasoline is decreased by at least ten percent as compared to yield from a catalytic cracking process using the initial zeolite.
14. The method of claim 1 , wherein said catalytic cracking conversion products include gasoline and yield of the gasoline is decreased by at least twenty percent as compared to yield from a catalytic cracking process using the initial zeolite.
15. A method of catalytic cracking of a hydrocarbon-containing feedstock to catalytic cracking conversion products, the method comprising:
providing, to a catalytic cracking process, a hierarchical zeolite composition prepared by:
mixing an alumina source, a silica source, and a zirconium source under reaction conditions to produce a zirconium-containing zeolite;
subjecting the zirconium-substituted zeolite to a framework modification process using a single template to produce a framework-modified zeolite; and
subjecting the framework-modified zeolite to an ion exchange process to produce a hierarchical pore structure in at least a portion of the framework-modified zeolite, resulting in the hierarchical zeolite composition; and
contacting a hydrocarbon-containing feedstock with the hierarchical zeolite composition at catalytic cracking conditions to produce catalytic cracking conversion products.
16. The method of claim 15 , further comprising:
steaming the hierarchical zeolite composition and mixing the hierarchical zeolite with kaolin in a 1:1 ratio to form a slurry containing the hierarchical zeolite and kaolin;
mixing the slurry containing the hierarchical zeolite and kaolin under heat to evaporate water and produce a hierarchical zeolite-kaolin powder mixture; and
subjecting the hierarchical zeolite-kaolin powder mixture to calcination, before contacting the hierarchical zeolite composition with the hydrocarbon-containing feedstock.
17. The method of claim 15 , wherein the zirconium source is one or more of zirconium chloride, zirconium sulfate, zirconium nitrate, and zirconium oxide.
18. The method of claim 15 , wherein the alumina source is sodium aluminate.
19. The method of claim 15 , wherein the silica source is colloidal silica.
20. The method of claim 15 , wherein a first mole ratio of the silica source and the alumina source ranges from 100 to 250 and a second mole ratio of the silica source and the zirconium source ranges from 20 to 250.