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基于水滑石(LDHs)层板元素的可调控性,采用共沉淀法制备了系列Cu、Mn双活性组分非贵金属CuMnMgAl-LDH催化剂,用于苯乙烯环氧化反应.受LDHs层板晶格定位效应的影响,活性组分高度稳定分散,与采用沉淀沉积法制备的负载型CuMnO_x/MgAl-LDH催化剂相比,苯乙烯转化率提高13.9%.且CuMnMgAl-LDH表面丰富的羟基结构,降低了催化剂的表面酸性,有效抑制了环氧苯乙烷(SO)的开环,从而提高了SO的选择性.进一步通过调变Cu/Mn摩尔比探究了双金属组分的协同作用对催化性能的影响.其中,Cu/Mn比为0.5:0.5时,Cu_(0.5)Mn_(0.5)Mg_5Al_2-LDH催化剂协同作用最强,具有最低的活化能(22.5kJ/mol)及最优的活性(97.3%)和选择性(66.3%),且催化剂经3次循环使用后,活性无明显下降.此外,发现溶剂与催化剂对氧化剂的活化存在竞争效应.
Based on the tunable properties of LDHs, a series of CuMnMgAl-LDH catalysts with Cu and Mn as binary active components were prepared by coprecipitation method for the epoxidation of styrene. The conversion of styrene increased by 13.9% compared with the supported CuMnOx / MgAl-LDH catalyst prepared by precipitation deposition method, and the abundant hydroxyl structure on the surface of CuMnMgAl-LDH decreased The surface acidity of the catalyst effectively inhibits the ring opening of the styrene oxide (SO), thereby increasing the selectivity of SO. Further, the synergistic effect of the bimetallic components on the catalytic performance Cu 0.5 Mn 0.5 Mg 5 Al 2 -LDH catalyst has the strongest synergistic effect with the lowest activation energy of 22.5 kJ / mol and the highest activity of 97.3% ) And selectivity (66.3%), and no significant decrease in activity after 3 cycles of the catalyst.In addition, it was found that the solvent and the catalyst had a competitive effect on the activation of the oxidant.