Modification of aluminophosphate molecular sieves by treatment with a silicon tetrafluoride gas mixture

摘要

Described herein is a process for enhancing the hydrophobicity of crystalline molecular sieves and also crystalline molecular sieve compositions which have enhanced hydrophobic character and modified catalytic properties. The crystalline molecular sieves are contacted with a silicon tetrafluoride gas mixture at a temperature from about ambient to about 200 DEG C. to alter (1) the framework aluminum and silica content, (2) the surface characteristics, and (3) the acidic sites of the molecular sieves with resulting modification of both the adsorptive properties, i.e., enhanced hydrophobicity, and catalytic properties of the molecular sieves. The crystalline molecular sieves can further undergo ion exchange to remove any aluminum fluoride cation species such as AlF++ and AlF2+. The crystalline molecular sieve compositions of this invention are useful as selective hydrophobic adsorbents and catalysts.