ZHANG Jian, HUANG Bangyin, SUI Zhijun, et al. Microkinetic analysis of acetylene hydrogenation over Pd-Ag/Al2O3 catalyst with different Pd/Ag ratios[J]. CIESC Journal, 2018, (2): 674-681. DOI: 10.11949/j.issn.0438-1157.20171007.
ZHANG Jian, HUANG Bangyin, SUI Zhijun, et al. Microkinetic analysis of acetylene hydrogenation over Pd-Ag/Al2O3 catalyst with different Pd/Ag ratios[J]. CIESC Journal, 2018, (2): 674-681. DOI: 10.11949/j.issn.0438-1157.20171007.DOI:
Selective acetylene hydrogenation is an important purifying reaction in ethylene industry. Pd-Ag/α-Al2O3 catalysts with different Pd/Ag ratios were prepared by stepwise incipient wetness impregnation method and characterized for structure and composition by N2-physisorption
XRD
ICP
XPS
TEM and CO chemisorption. A microkinetic model of acetylene hydrogenation over these catalysts was established from a fractional factorial design of experiment and effects of Ag amount on the hydrogenation kinetics were analyzed through microkinetic simulation and parameter value change. After values for basic parameters used DFT calculation results of C2 hydrogenation over Pt-Ag catalysts and activation energies optimized by adsorption-desorption steps
the microkinetic model could fit kinetic experiment results quite well on acetylene hydrogenation over all catalysts of various Pt-Ag ratios. The study showed that C2H4* was the most abundant surface species and vinyl hydrogenation was rate control step
which did not change with increase of Ag content. However
the increase of Ag greatly reduced activation energy of hydrogen desorption and improved ethylene selectivity. This phenomenon might be correlated to enhancement of electron transfer from Ag to Pd on the catalyst surface upon increase of Ag content.