A theoretical study on the adsorption of an all-metal aromatic molecule Na2Al4 on MCM-22 zeolite

In light of the excellent adsorption of zeolites, we firstly propose by means of density functional theory calculations that all-metal aromatic molecules like Na2Al4 could be effectively adsorbed into the supercage of MCM-22, which provides a potential way to stabilize the Na2Al4 molecule. Our calculations also show that the adsorption of Na2Al4 would induce the jumping of the protons in zeolite to other oxygen atoms in the vicinity of Al. Comparing the local mobility of protons before and after the Na2Al4-adsorption, the proton migration barrier is significantly reduced from 45.9 to 29.0 kJ/mol. Therefore, the adsorption of the all-metal aromatic molecule Na2Al4 can effectively increase the local mobility of proton and improve the acidity of zeolite. Thus, our work provides a new way to improve the acidity of zeolites and the ability of proton transferring by adsorption of guest molecule Na2Al4 on zeolites.