Effects of Ca on the Structure of Cu/B/Ca/Al_2O_3 and Its Catalytic Performance in the Hydrogenation of sec-Butyl Acetate
JIA Chang-bin;LUO Xue-qing;SUN Pei-yong;ZHANG Sheng-hong;YAO Zhi-long;Beijing Key Laboratory of Enze Biomass Fine Chemical,College of Chemical Engineering,Beijing Institute of Petrochemical Technology;College of Chemical Engineering,Beijing University of Chemical Technology;
A series of Cu / B / Ca / Al2O3 catalysts with different Ca O contents were prepared by the wet impregnation step by step and studied in the hydrogenation of sec-butyl acetate to sec-butanol. Effects of Ca O contents on the c atalyst structure,reducibility,acidity and the dispersion of metallic copper were evaluated by XRD,H2-TPR,XPS,NH3-TPD and N2O-H2 redox titration,respectively. It was shown that a low content of Ca O in the catalyst had little influence on the dispersion of copper,but the high loading of Ca O( 20%) reduced the surface area of catalyst greatly and led to a worse dispersion of copper. However,calcium as an electron-denoting element could compensate effectively the electron withdrawing from copper to B2O3,improving the catalytic activity for the hydrogenation of esters. Moreover,addition of Ca O could eliminate the strong acid sites on the surface of Cu / B / Ca / Al2O3 and reduce its total amount of acid,resulting in the lower acid-catalyzed products,as well as the less carbon deposition on the catalyst surface.