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US 4,088,605 AGranted
ZSM-5 containing aluminum-free shells on its surface
AssigneeMobil Oil Corporation
InventorLouis D. Rollmann
Life of this patent
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Abstract
Aluminosilicate zeolites are prepared containing an outer aluminum-free shell. The outer shell is essentially SiO.sub.2 that has crystallized on the zeolite surface in the ZSM-5 type configuration, leading to a more selective catalyst.
Claims20
A composition comprising a crystalline aluminosilicate zeolite having an aluminum-free outer shell of SiO.sub.2, said zeolite being made by a two stage method comprising:
- (1) initiating crystallization in a crystallization medium to produce the zeolite and
- (2) altering the crystallization medium to substantially eliminate the aluminum therein
- said outer shell of SiO.sub.2 having the same crystal structure as said zeolite.
A method for making a composition comprising a crystalline aluminosilicate zeolite having an aluminum-free outer shell of SiO.sub.2 having the same crystal structure as said zeolite, said method comprising the steps of:
- (1) initiating crystallization in a crystallization medium to produce the zeolite and
- (2) altering the crystallization medium to substantially eliminate the aluminum therein.
Dependencies are inferred from the claim text.