Ethylene and propylene production from ethanol over Sr/ZSM-5 catalysts: A combined experimental and computational study

Protonated ZSM-5 zeolites doped with alkaline earth metals (M/ZSM-5, M: Mg, Ca, Sr and Ba) were prepared by impregnation method. The effects of reaction conditions and alkaline earth metals modifications on the conversion of ethanol to olefins were systematically investigated. The maximum yield of propylene reach 29.8 %. The physical and chemical properties of the catalysts were characterized by X-ray diffraction, N2 adsorption-desorption measurement, and temperature programmed desorption of ammonia. The structure and electronic properties of Sr modified ZSM-5 catalysts were studied by density functional theory. The calculation results demonstrate that the adsorption of ethanol on Sr/ZSM-5 catalyst is more suitable, while ethylene and propylene are more easily desorbed on Sr/ZSM-5. Simultaneously, the activation energy of ethylene protonation reaction increases after Sr modification, which could suppress the carbon deposition. The lifetime of the catalyst is prolonged. The experimental results of enhanced selectivity and stability could be interpreted from the computational study.