A comparative study of Pd/SiO_2 and Pd/MCM-41 catalysts in liquid-phase hydrogenation

摘要

The characteristics and catalytic properties of Pd/MCM-41 and Pd/SiO_2 were investigated and compared in terms of Pd dispersion,catalytic activities for liquid-phase hydrogenation of 1-hexene,and deactivation of the catalysts.High Pd dispersion was observed on Pd/MCM-41-large pore catalyst while the other catalysts showed relatively low Pd dispersion due to significant amount of Pd being located out of the pores of the supports.Based on CO chemisorption results,the catalyst activities seemed to be primarily related to the Pd dispersion and not to diffusion limitation since TOFs were nearly identical for all the catalysts used in this study.In all cases,leaching and sintering of Pd caused catalyst deactivation after 5-h batch reaction.However,compared to Pd/SiO_2 with a similar pore size,Pd/MCM-41 exhibited higher hydrogenation activity and lower amount of metal loss.