钌钯双金属催化剂固载顺序控制及性能

Immobilization Sequence Control and Properties of Bimetallic RuPd Catalysts for Selective Hydrogenation

摘要:

以Al2O3、PdCl2和RuCl3为原料，采用溶液浸渍法，通过控制固载顺序、制备流程以及焙烧温度等条件，制得系列负载型RuPd双金属催化剂，并用于对苯二甲酸二甲酯（DMT）制取1，4-环己烷二甲酸二甲酯（DMCD）的选择加氢过程。其中，Ru和Pd的总负载量为0.3%（以催化剂的总质量为基准，下同），且m(Ru)∶m(Pd)=1∶1。结果发现，采用先Ru后Pd（Ru-Pd）式固载顺序和浸渍-干燥-浸渍-干燥-焙烧（IEIEC）型制备流程，并在450℃下焙烧后，所得负载型RuPd双金属催化剂的反应性能最佳，在6 MPa，180℃下，DMT转化率为89.6%，DMCD选择性为96.0%，DMCD产率为85.9%。这可能与其大粒径粒子的形成受到抑制、粒径尺寸和分布更小、比表面积和总孔容更高、表面Pd原子摩尔占比较高以及Ru/Pd摩尔比例较低有关。

Abstract:

A series of supported bimetallic RuPd catalysts were prepared by wet impregnation method using Al2O3, PdCl2 and RuCl3 as raw materials under the conditions of controlling the immobilization sequence, prepa-ration process and calcination temperature. And then these catalysts were used for the selective hydro-genation of dimethyl terephthalate (DMT) to dimethyl cyclohexane-1,4-dicarboxylate (DMCD). In which, the total loading of Ru and Pd was 0.3% (based on the total mass of the catalyst, the same below), and m(Ru) : m(Pd)= 1:1. The results showed that the catalyst had the best catalytic performance which was prepared using impregnation sequence of first Pd then Ru (Ru-Pd type) and impregna-tion-drying-impregnation-drying-calcination (IEIEC) preparation process and then calcinated at 450℃. Under 6.0 MPa and 180℃, the DMT conversion, DMCD selectivity and DMCD yield reached 89.6%, 96.0%, and 85.9%, respectively, which could be ascribed to the inhibition of the formation of large particle size, the smaller particle size and distribution, the higher specific surface area and total pore volume, the higher molar proportion of surficial Pd, and the lower surficial Ru/Pd molar ratio.