Preparation And Catalitic Performance Of Egg-Shell Nano-Catalyst On The Selective Hydrogenation Of Acetylene

Novel porous hollow silica nano-particles (PHSNs) were used as the support to prepare egg-shell shaped Pd nano-catalysts. The catalytic performance of the prepared catalysts for the selective hydrogenation of acetylene were studied systematically, and its reaction kinetic was explored preliminarily as well.Porous hollow silica nano-particles were synthesized with nano CaCO3as template and sodium silicate as the silica source. PHSNs have a diameter of60-100nm, a specific surface area of400-1000m2/g, a pore diameter of2-7nm and a wall thickness of5-50nm. Then unpromoted and Ag promoted Pd-based egg-shell catalysts were prepared by an impregnation method using PHSNs as supports and PdCl2as the precursors. TEM, XRD, TPR and ICP analyses showed that Pd was loaded on the support in the form of small PdO particles with fine dispersion, while Ag and Pd formed Pd-Ag alloy on the catalyst support.The catalytic performance of the prepared egg-shell Pd nano-catalysts for the selective hydrogenation of acetylene was investigated. By varying the reduction temperature, reduction time and space velocity, it was found that the optimal space velocity for the catalysts is4320mL·g-l·h-1and the suitable H2/C2H2is2:1at the optimal reaction temperature of40～45℃and reaction pressure of0.1MPa. Adding a proper amount of Ag promoter could improve the selectivity of the catalyst, but it would lower the conversion rate at the same time. If too much Ag was added, both conversion rate and selectivity would be reduced. Through calculating the constant of reaction rate at different temperatures, A0(8.965-e10h-1) and the reaction energy Ea (78.99KJ/mol) were obtained, leading to reaction kinetic formula as...