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Abstract: Zirconia catalysts doped with Si were prepared by co-precipitation method. The effects of zirconium precursor, precipitant and Si on the selective conversion of ethanol to ethylene over zirconia catalysts were investigated. The addition of Si afforded high surface area and enlarged amount of acidic sites. Higher ethanol conversion and ethylene yield were obtained over SiO2-ZrO2 catalysts. The highest yield of ethylene reached 95.9% over SiO2-ZrO2 synthesized by ZrO(NO3)2·2H2O and (NH2CH2)2.Graphical Abstract: [ABSTRACT FROM AUTHOR]

A series of alkaline earth metal-doped M/ZrO2 catalysts (M = Mg, Ca, Sr, and Ba) were prepared by co-precipitation method. The influence of alkaline earth metal on the physicochemical properties and catalytic performance of M/ZrO2 catalysts in the conversion of ethanol was investigated. The catalysts were characterized by N2 adsorption/desorption method, temperature programmed desorption and X-ray diffraction. It was revealed that the introduction of alkaline earth metal changed the acidity/basicity of catalysts and positively enhanced catalytic performance in the ethanol conversion to olefins reaction. The ethylene yield increased with the introduction of alkaline earth metals, which was attributed to higher amount of strong acid sites. The maximum yield of ethylene and propylene reached 80.8% over Sr(1)/ZrO2 catalyst. The adsorption of ethanol on perfect-ZrO2(101) and Sr/ZrO2(101) surfaces was investigated with density functional theory. The adsorption for ethanol on Sr/ZrO2(101) surface was more stable than on perfect-ZrO2(101). The ethanol molecule has stronger interaction with Sr/ZrO2(101) surface than perfect-ZrO2(101) surface. [ABSTRACT FROM AUTHOR]

[Display omitted] • Propylene selectivity is enhanced over Sr/ZSM-5 for ethanol conversion. • Catalytic stability is also improved on Sr/ZSM-5 in ethanol conversion. • Sr modification changes the electronic environment of active sites on HZSM-5. • Ethanol is better to absorb and propylene are easier to desorb on Sr/ZSM-5 catalyst. • Sr modification inhibits the ethylene dimerization and coking for ethanol conversion. 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, N 2 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. [ABSTRACT FROM AUTHOR]