Potassium regulating electronic state of zirconia supported palladium catalyst and hydrogen spillover for improved acetylene hydrogenation

High-selectivity acetylene hydrogenation to produce ethylene is an important issue of removing acetylene im-purity in ethylene for industrial polyethylene production. Developing high-efficiency catalyst with excellent ethylene selectivity and catalytic durability is desirable but still challenging. In this work, potassium doped palladium catalysts supported on zirconia with different K contents (Pd/ZrO2-xK) have been developed to catalyze acetylene hydrogenation, the Pd/ZrO2-16K exhibits impressive catalytic performance with acetylene conversion of 100 %, ethylene selectivity of 81 % and high catalytic durability. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), in situ synchrotron radiation photoionization mass spectrometry (SR-PIMS) and density functional theory (DFT) calculations reveal that K doping effectively weakens the adsorption of ethylene by regulating the electronic state of catalyst to improve ethylene selectivity and substantially lowers the barriers of hydrogen activation and transfer reactions to favor hydrogen spillover, thus conferring a remarkably improved durability on the Pd/ZrO2-16K catalysts.