FINE CONTROL OF HZSM-5 PORE-OPENING SIZE BY A NEW CVD METHOD

A new CVD method without vacuum condition (CVDWV) was designed in this study, it had been found that by modifying the now rate of the carrie r gas (N-2) and the temperature of surface reaction, silicon saturator and sample tube, the amount of silica deposited on the external surfa ce of the zeolite could be precisely controlled, The changes in the ph ysicochemical properties of zeolite, such as pore-opening size, acidit y and reaction property were investigated. The results obtained showed that: modification of the improved CVD method did not change the inte rnal structure and acidity of the zeolite, but could bring about signi ficant change of pore-opening size and reaction property as desired.