Towards the Design of Aluminosilicate Catalyst: Measurements and Understanding of Origin of the Acidic Property of Solid

摘要

We have developed a method of ammonia IRMS-TPD (infrared / mass spectroscopic temperature-programmed desorption) to measure the number and strength of each of Bronsted and Lewis acid sites on a solid. The measured number of the Bronsted acid sites are close to the number of framework Al atoms. The energy of ammonia desorption is principally dependent on the framework type, but less sensitive to the composition. The density functional theory (DFT) clarified that the compression from the both ends of SiOHAl unit is the origin of Bronsted acidity, and therefore the acid strength was dependent on the framework topology.