Speakers

Biography

Daoming Jin, born in China, is studying for a doctorate at the East China University of Science and Technology. His research focuses on C1 catalysis, especially for the design of metal oxides and zeolites. He has published four articles in ACS Sustainable Chemistry & Engineering, Industrial & Engineering Chemistry Research, and Molecular Catalysis.

Abstract

A bifunctional catalyst composed of metal oxides and zeolites has been a promising method for directly converting syngas to light olefins (STO). Metal oxides have significant effects on the adsorption and activation of CO. ZnCrO_x oxides activate syngas and do not cause the deep hydrogenation of light olefins to paraffin, so they are usually coupled with SAPO-34 zeolite to constitute bifunctional catalyst applied in STO reaction. The ZnCrOx oxides need to be modified to improve the conversion of syngas.

A series of ZnCrO_x oxides were prepared by co-precipitation method with different concentrations of precipitant and various atmospheres of precipitate treatment. The characterization results indicated that more oxygen vacancy could be generated by higher concentrations of precipitant and hydrogen treatment and further benefitted to chemical adsorption of CO. The density functional theory (DFT) calculations confirmed that more oxygen vacancy could reduce the adsorption energy of CO, and the formation energy of oxygen vacancy under a hydrogen atmosphere was lower than that under an oxygen atmosphere. More oxygen vacancy on the surface of metal oxides promoted the chemical adsorption and conversion of CO. The ZnCrO_x with the highest oxygen vacancy concentration and SAPO-34 achieved the CO conversion of 43% and the C₂⁼-C₄⁼ selectivity of 86 % at 4 MPa and 5400 mL g^-1 h^-1. After a reaction of about 100 h, the bifunctional catalyst still exhibited the CO conversion of 35% with the C₂⁼-C₄⁼ selectivity of 88%. These results suggested that improving the surface oxygen vacancy of metal oxides can be an effective method for designing catalysts with high catalytic performance for directly converting syngas to light olefins.