Insights into Promoting Effect of Sm on Catalytic Performance of the CeO2/Beta Catalyst in Direct Conversion of Bioethanol to Propylene

A series of Sm-doped CeO 2 /Beta composite catalysts with various Sm/Ce atomic ratios(0.1–0.4) were prepared by an incipient impregnation method, followed by calcination at 650 °C. They were characterized by X-ray diffraction(XRD), N 2 adsorption, X-ray photoelectron spectroscopy(XPS), Raman, NH 3 -temperature programmed desorption(TPD) and CO 2 -TPD. The incorporation of Sm into CeO 2 /Beta increases obviously the propylene yield for the selective conversion of ethanol to propylene. The promoting effect of Sm on CeO 2 /Beta can be attributed to two reasons. One is more acetone intermediates are generated on the Sm-doped catalysts due to the enhanced formation of oxygen vacancies. The other is the conversion of acetone intermediate to propylene is enhanced owing to weaker and fewer acid sites on the Sm-doped catalysts.