LIQUID-PHASE HYDROGENATION OF ACETYLENE IN A MONOLITHIC CATALYST REACTOR

The selective, liquid-phase hydrogenation of acetylene in the presence of excess ethylene has been studied. A new process using a monolith r eactor is presented. The liquid, heptane, was used to continuously rem ove the green oil formed by polymerization. The Liquid also absorbs mo st of the heat formed in the exothermic hydrogenation reactions. The t otal pressure was 1.3-2.0 MPa and the temperature was 303-313 K. Sever al Pd catalysts supported on alumina have been tested. The best select ivity was obtained using an a-alumina support with an average pore dia meter of 0.08 mu m. This reaction is known to be structure-sensitive i n the gas phase and the same was found for the liquid phase. The best catalyst was tested for a total of 113 h. The activity in the acetylen e hydrogenation reaction and the selectivity toward ethylene dropped d uring the first 60 h of reaction (turnover number from 3 to 1 s(-1) an d selectivity from 80 to 55%). After that period, both remained approx imately constant.