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金属-有机骨架材料不仅比表面积大、孔隙率高、孔道规则,而且化学性质和结构性质多样、可调,所以在近年来受到了研究者的广泛关注.合成了MIL-53(Al)、MIL-53(Cr)及新颖的含有二元配位金属的MIL-53(Al_xCr_1)(x=1,2,3,4)材料,以此为载体采用浸渍-化学还原法制备了Ru-B/MIL-53催化剂,考察了它们在苯部分加氢制环己烯反应中的催化性能.催化剂评价结果表明,Al/Cr比不仅影响Ru-B/MIL-53催化剂上的初始反应速率(r0),也影响环己烯的初始选择性(S0).一般而言,高Al含量的MIL-53作为载体对r0有利,而含有二元配位金属的MIL-53作为载体时,S0高于仅有单一配位金属的MIL-53载体.在环己烯选择性最高的Ru-B/MIL-53(Al_3Cr_1)催化剂上,r0和S0分别为9.2 mmol/(min·g)和71%.采用多种手段,对环己烯选择性差异最为显著的Ru-B/MIL-53(Al_3Cr_1)和Ru-B/MIL-53(Cr)催化剂的物化性质进行了对比研究,发现二者Ru-B纳米粒子的化学组成、电子性质、微观结构接近,但前者的活性表面积大于后者,Ru-B粒子的尺寸更小,分散更加均匀,且金属-载体作用更强.更小的Ru-B粒径不仅能够提供更多的活性位,而且也有利于环己烯选择性的提高.通过对反应条件进行优化,在180℃和5.0 MPa H_2压力下,以100mL乙醇胺为修饰剂时,在Ru-B/MIL-53(Al_3Cr_1)催化剂上可得环己烯得率29%的结果.
In recent years, metal-organic framework materials have attracted a great deal of attention from researchers because of their large specific surface area, high porosity and regular pore channels, and their chemical and structural properties are diverse and adjustable.MIL-53 (Al), MIL (Al_xCr_1) (x = 1, 2, 3, 4) with binary coordination metal-53 (Cr) and Ru-B / MIL-53 catalysts were investigated for their catalytic performance in the partial hydrogenation of cyclohexene to benzene. The catalyst evaluation results show that Al / Cr ratio not only affects the initial reaction rate (r0) on the Ru-B / MIL- , But also affect the initial selectivity of cyclohexene (S0) .Generally, the high Al content of MIL-53 as a carrier for r0 beneficial, and binary binary metal containing MIL-53 as a carrier, S0 higher than only MIL-53 with a single coordination metal, r0 and S0 are 9.2 mmol / (min · g) and 71% respectively on Ru-B / MIL-53 (Al_3Cr_1) catalysts with the highest selectivity to cyclohexene. The comparison of the physico-chemical properties of Ru-B / MIL-53 (Al 3 Cr 1) and Ru-B / MIL-53 (Cr) catalysts with the most significant differences in cyclohexene selectivity found that Ru-B Nanoparticles The chemical composition, the electronic properties and the microstructure are close, but the former has a larger active surface area than the latter, the size of the Ru-B particles is smaller, the dispersion is more uniform and the metal-carrier function is stronger. The smaller Ru-B particle size can not only Which can provide more active sites and also improve the selectivity of cyclohexene.By optimizing the reaction conditions, under the conditions of 180 ℃ and 5.0 MPa H 2 pressure with 100mL ethanolamine as modifier, Ru-B / MIL -53 (Al_3Cr_1) catalyst gave a cyclohexene yield of 29%.