QM:QM studies on the mechanisms of interaction of alkenes with zeolitic Brønsted sites in H-FER

Abstract

The chemically accurate hybrid MP2:(PBE + D2) + ΔCCSD(T) method is used to search the transition states for five reactions of alkenes with the Al(2)O(7) Brønsted acid site in H-ferrierite (H-FER). The relative energy barriers for the alkene adsorption on Brønsted sites of BAS are obtained at both PBE + D2 and MP2 + ΔCC level. The results show that MP2 + ΔCC intrinsic energy barriers are higher than corresponding PBE + D2 intrinsic energy barriers about 32–42 kJ/mol. For the primary or secondary carbocation-like transition states, the relative energies decrease with the increase of the carbon number. For the reactant of propene, the conversion into 2-propoxide is energetically more favored than the conversion into 1-propoxide.