Fabrication Of Different Shape CeO₂ Load Au Catalysts For Phenylacetylene Selective Hydrogenation

Styrene is a kind of chemical raw material which is widely used in petrochemical industry,polymer material and pharmaceutical synthesis.However,styrene materials usually contain a small amount of phenylacetylene,which can seriously affect the quality of styrene downstream products.Therefore,it is necessary to remove phenylacetylene by efficient catalytic hydrogenation.The Au-based catalyst has good selectivity of styrene,but its hydrogenation activity needs to be further improved.Regarding the issue above,this paper starts with the the control of supports’morphology and diversification of active components.With the help of metal-support interactions and bimetallic synergies to achieve the catalytic hydrogenation performance enhancement of Au-based catalysts.In the beginning,based on the adjustable morphology of CeO2,three kinds of CeO2 carriers with cube,polyhedron and short rod morphology were synthesized by hydrothermal method.Using the precipitation deposition method was adopted to construct a series of Au/CeO2 catalysts.Then,the dispersion degree,distribution structure,elemental valence state and interaction effect of CeO2 crystal surface were investigated,and the performance evaluation was performed in the selective hydrogenation of phenylacetylene.According to the representation,the active component Au has high dispersion degree and high Au0 content compared with the CeO2 carrier of the polyhedron and the short rod morphology.In addition,the Au/CeO2 catalyst has the highest oxygen vacancy content and strong metal-support interactions.The active component Au anchored and highly dispersed on the CeO2-NC surface.Au/CeO2-NC catalyst showed the best catalytic performance because of its highest dispersion,Au0 ratio and Ce3+content.Finally,used sheet-like CeO2 as supports and based on the diversity of active components,Pd as the second metal component was introduced.The C-AuPd/CeO2,D-AuPd/CeO2 and R-AuPd/CeO2 nanocatalysts were prepared by co-sedimentation reduction,precipitation deposition and sol fixing method.The effects of different load methods on the hydrogenation of AuPd/CeO2 catalyst were discussed.The results show that the formation of AuPd alloy can reducc the electron cloud density of Pd and increase the non-continuous Pd activity site,thus improving the selectivity of styrene.In addition,a large number of Ce3+can effectively inhibit the polymerization of styrene,thereby reducing the generation of polymers.The C-AuPd/CeO2 catalyst showed the optimal catalytic performance because of its uniform AuPd alloy structure and the highest Ce3+content.When the conversion rate of phenyl acetylene reached 98.8%,the styrene selectivity was up to 92.0%.