A series of CaO-added Pd-Ag/Al2O3 catalysts for selective hydrogenation of acetylene were prepared by impregnation method. The maximum dispersion of palladium was observed at the atomic ratio of Ca to Pd 6 by means of CO-TPD method. It was found that the acetylene conversion on CaO-added Pd-Ag/Al2O3 decreased with the increase of CaO content in the reaction temperature range of 50-90 ℃. When the atomic ratio was 6, 8, or 10, the conversion and selectivity on the modified catalyst was improved in the reaction temperature range of 90-100 ℃. The catalysts were characterized by means of in situ DRIFTS and TG-DSC. It was demonstrated that the amount of green oil adsorbed on CaO-added catalyst was decreased, though the carbon chains of the green oil molecules were longer.%以CaO为改性助剂,采用等量浸渍法对工业用乙炔选择加氢催化剂Pd-Ag/Al2O3进行改性,制备了CaO含量不同的改性Pd-Ag/Al2O3催化剂.CO-TPD表征结果显示,Ca与Pd原子比为6时,改性催化剂中Pd的分散度最大.在高通量微型反应器上对催化剂进行活性评价的结果表明,当反应温度为50 - 90℃时,改性催化剂的活性随CaO含量的增加而降低；当反应温度为90～ 100℃时,Ca与Pd原子比为6,8,10的改性催化剂的活性和选择性都得到提高.原位DRIFTS及TG-DSC分析结果表明,采用CaO改性虽使催化剂上吸附的碳氢化合物的链长增长,但有助于降低碳氢化合物的吸附量.
展开▼
