Enhanced the dehydrocyclization of 1,4-butanediol to γ-butyrolactone via the regulation of interface oxygen vacancies in Cu/MgO-CeO2 catalyst

Abstract

Gas-phase dehydrocyclization of biomass-derived 1,4-butanediol (BDO) to γ-butyrolactone (GBL) is a sustainable and environmentally friendly process conducted at atmospheric pressure. In the present work, a series of 15Cu/xMgO-yCeO2 catalysts with different MgO: CeO2 ratios were prepared by the ammonia vaporization method. The gas-phase dehydrocyclization of BDO to GBL was carried out over these Cu-based catalysts synthesized in a fixed-bed reactor. The physicochemical properties of the catalysts were investigated by XRD, SEM, TEM, FTIR, N2 isothermal adsorption–desorption, H2-TPR, CO2-TPD, Raman, XPS, and EPR. The results indicated that the 15Cu/10MgO-90CeO2 catalyst exhibited a smaller particle size, higher specific surface area, and increased oxygen vacancies than the 15Cu/CeO2 catalyst. Operating conditions of 240 °C reaction temperature, 2.4 mL/h space velocity, and 98.92 % GBL yield from BDO dehydrogenation were achieved under 40 mL/min N2 flow for 4 h. Density functional theory (DFT) calculations confirmed that the 15Cu/10MgO-90CeO2 catalyst with more oxygen vacancies was more favorable for the adsorption and activation of BDO on the catalyst surface than 15Cu/CeO2, and its higher catalytic activity was attributed to the synergistic interaction between Cu+ and oxygen vacancies on the catalyst surface.