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US 6,632,767 B2Granted
Stabilization of molecular sieves by salt addition
AssigneePraxair Technology, Inc.
InventorsQisheng Huo, Neil Andrew Stephenson
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Abstract
The low stability of some molecular sieves can be overcome during calcination by a solid state reaction between the molecular sieve and a salt. Molecular sieves including zeolites, metal substituted aluminosilicates, and metallosilicates can be stabilized by this method. The inventive process comprises mixing such molecular sieve with a salt, either directly or as a slurry; and then heating the resulting mixture to remove water, organics and adsorbed species.
Claims6
A method for thermally stabilizing an unstable molecular sieve comprising the following steps:
- a) mixing the unstable molecular sieve with a salt, either directly or as a slurry;
- and
- b) heating the mixture that results from step a) to remove one or more of water, organics. and adsorbed species;
- wherein the unstable molecular sieve adsorbent is either a zeolite, a metal substituted aluminosilicate where the metal is one or more of Zn, Fe, Ga., Ge, Co, Ti, Ni and Mn, or a metallosilicate where the metal is one or more of Zn, Fe, Ga, Ge, Co, Ti, Ni and Mn;
- wherein said salt is a tetraalkylammonium salt;
- and
- wherein step b) comprises calcining the mixture at a temperature in a range of from 300° C. to 800° C., at a rate of heat increase of 0.1° C. to 10° C. per minute during a heating time of 0.1 to 60 hours and removing excess amounts of said salt from said unstable molecular sieve.
4 more elements
Dependencies are inferred from the claim text.