Unravel the Roles of the Acid Sites in Different Pore Channels of HZSM-5 Catalyst on Ethanol Conversion to Light Olefin

Catalytic conversion of bioethanol is a promising production method for preparing light olefin. However, the role of acid sites in different pore channels of HZSM-5 catalyst is not clear. The roles of acid sites in different channels of HZSM-5 catalyst on the conversion of ethanol to ethylene and propylene was investigated by density functional theory (DFT). The results show that the conversion of ethanol to ethylene mainly occurs at the acid site of the sinusoidal channel (T11) of HZSM-5, and the conversion of ethanol to propylene mainly occurs at the acid site of the straight channel (T10) of HZSM-5 catalyst. The adsorption and diffusion behaviors of ethylene and propylene in straight and sinusoidal channels of HZSM-5 were simulated by the molecular dynamics method. The results show that for the adsorption of ethylene and propylene, the acid sites of sinusoidal channel (T11) with SiO2/Al2O3 = 128 is more conducive to improving the selectivity of ethylene, and the acid sites of straight channel (T10) with SiO2/Al2O3 = 128 is more conducive to improving the propylene selectivity. For the diffusion of ethylene and propylene, the acid sites in the straight channel (T10) of HZSM-5 (SiO2/Al2O3 = 128) are more beneficial to improve propylene selectivity.