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用共沉淀法分别在5%NaOH溶液、蒸馏水、0.035mol/L ZnSO4溶液和0.145mol/L ZnSO4溶液中用H2还原制备了Ru-Zn(5%NaOH)催化剂、Ru-Zn(H2O)催化剂、Ru-Zn(0.035mol/L ZnSO4)催化剂和Ru-Zn(0.145mol/L ZnSO4)催化剂。结果表明,它们催化苯选择加氢制环己烯的活性高低顺序为Ru-Zn(5%NaOH)催化剂>Ru-Zn(H2O)催化剂>Ru-Zn(0.035mol/L ZnSO4)催化剂≈Ru-Zn(0.145mol/L ZnSO4)催化剂,环己烯选择性高低顺序与活性顺序正好相反。因为还原介质可以影响Ru-Zn催化剂的组成和织构性质,进而影响它的催化性能。Ru-Zn(H2O)催化剂的环己烯收率最高,说明蒸馏水作还原介质最好。随还原温度升高,Ru-Zn(H2O)催化剂比表面积逐渐减小,催化剂活性逐渐降低。同时粒径逐渐增大,Ru粒子上有利于环己烯加氢生成环己烷的楞位和顶点位减少,环己烯选择性升高。在100℃还原温度下制备的Ru-Zn(H2O)催化剂的环己烯收率可达58.1%。
Ru-Zn (5% NaOH) and Ru-Zn (H2O) catalysts were prepared by coprecipitation method in H2SO4 solution of 5% NaOH solution, distilled water, 0.035mol / L ZnSO4 solution and 0.145mol / Ru-Zn (0.035 mol / L ZnSO4) catalyst and Ru-Zn (0.145 mol / L ZnSO4) catalyst. The results showed that the order of their catalytic activities for the selective hydrogenation of benzene to cyclohexene was as follows: Ru-Zn (5% NaOH) catalyst> Ru-Zn (H2O) catalyst> Ru-Zn (0.035mol / L ZnSO4) Zn (0.145mol / L ZnSO4) catalyst, cyclohexene selectivity in the order of the opposite order of activity. Because the reduction medium can affect the composition and texture properties of the Ru-Zn catalyst, thereby affecting its catalytic performance. The highest yield of cyclohexene was found for Ru-Zn (H2O) catalyst, which showed that distilled water was the best reduction medium. With the increase of reduction temperature, the specific surface area of Ru-Zn (H2O) catalyst decreases gradually and the activity of catalyst decreases. At the same time, the particle size increased gradually, and the position of aurora and apex on hydrogenation of cyclohexene to cyclohexane on Ru particles decreased, and the selectivity of cyclohexene increased. The yield of cyclohexene of Ru-Zn (H2O) catalyst prepared at the reduction temperature of 100 ℃ can reach 58.1%.