The maximum overlap method was used to study the relationships the C-H stretching frequencies, group electronegativities and proton acidity properties and the molecular structure in the halomethanes.
According to the great influence of system acidity and alkalinity on MCM41 molecular sieve formation in hydrothermal condition, a detailed formation mechanism of MCM41 was proposed.
Latest researches in SAPO-18 molecular sieve were reviewed with respect to its synthesis, structure, acidity and application in methanol-to-olefins (MTO) process.