Synthesis And Application Of CuZn Alloy Catalyst And Hierarchical Porous Support

Cu-Zn catalysts have wide application in industry due to its low cost,abundant reserves and high catalytic activity.Support is the base of a catalyst,which can improve the dispersion of active sites,support the whole structure,and even cooperate with the active sites to form a bifunctional catalyst.Therefore,there is an important influence on the catalytic performance to select a suitable support.But the support used in Cu-Zn catalyst do not have good pore properties and high specific surface area,thus it fails to exert the maximum advantage of the support and affect the particle size and dispersion of the active sites.Alumina and zeolites are ideal supports with broad application prospects due to their good thermal stability,adjustable pore structure and good chemical stability.Therefore,in order to solve the problems in support,this work focuses on the hierarchical?-Al₂O₃ and titanium silicalite-1 zeolite with excellent pore properties and high specific surface area,and then prepares the hierarchical porous materials supported CuZn alloy catalysts.The catalyst performance is evaluated in the hydrogenation of 1,3-butadiene reaction and reduction reaction of p-nitrophenol.The main research contents and conclusions obtained are as follows:?1?Hierarchical?-Al2O3 was prepared by one-step method.The hierarchical structure can increase the specific surface area up to 394 m²/g and improve the loading of the active sites.Meanwhile,it can provide excellent transport channels for the diffusion of substances.The hierarchical?-Al2O3 supported CuZn alloy catalysts maintain a high specific surface area?259 m²/g³55 m²/g?and good pore structure.The catalyst performance in the selective hydrogenation of 1,3-butadiene revealed that it exhibited a ultra-high stability with the conversion of 1,3-butadiene above 50%after reaction for 70 h.?2?Hierarchical titanium silicalite-1 zeolite was prepared by steam-assisted dry gel method with the hierarchical macro-mesoporous carbon as the hard template.It can provide an excellent transport channel for the reaction diffusion,because different kinds of pores are concentrated in one system.The hierarchical titanium silicalite-1 zeolite supported CuZn alloy exhibited excellent performance in the reduction of p-nitrophenol.The conversion of p-nitrophenol reached 83.5%after reaction for 25 minutes.And when the catalyst used in the reaction of the selective hydrogenation of 1,3-butadiene,the selectivity to butenes was always maintained above 97%,the conversion of 1,3-butadiene reached 100%at 175?,and the conversion of 1,3-butadiene was only dropped from 70%to 58%after reaction for24 h.?3?Hierarchical titanium silicalite-1 zeolite microspheres was prepared by microfluidic technology with polystyrene beads as a macroporous template.The volume ratio of polystyrene beads to zeolite precursor and crystallization time had been investigated.The results showed that the morphology and structure of microspheres remained best when the volume ratio of polystyrene beads to zeolite precursor is 74:26.When the zeolite precursor is not enough?74:13?or too much?74:39?,the structure was easily collapsed or the pore structure disappeared due to the excessively grow of nanocrystals.The crystallinaty and size of nanocrystals increased with the prolong of the crystallization time.The zeolite microspheres with the specific surface area of 343 m²/g maintained a good crystallinity and structure when the crystallization time was 36 h.