Effect of Water Vapor Pressure on Dealumination Rate of HZSM-5 Zeolite

Abstract

Dealumination rate of HZSM-5 zeolite under various water vapor pressures was investigated by means of ²⁷ Al MAS NMR. The dealumination rate was markedly dependent on the water vapor pressure. Under water vapor pressure ranging from 0.1 to 1 kg/cm², it was found that the dealumination rate was apparently third-order dependent on the content of framework aluminum and approximately 1.5-order dependent on water vapor pressure. Based on these results, a plausible mechanism of dealumination of HZSM-5 zeolite by steaming was proposed.