【摘要】 以碱金属、碱土金属硝酸盐作为助剂前体,活性炭为载体制备了系列负载型钌催化剂,采用物理吸附、化学吸附和XRD等表征手段,考察了助剂对Ru C催化剂的比表面、孔分布和钌分散度的影响,并在430℃、10 0MPa和10000h-1条件下进行氨合成活性评价。结果表明,单助剂Ru C催化剂,碱金属助剂的促进作用与其相应氢氧化物碱性变化规律一致,碱土金属助剂的促进作用与其相应氧化物碱性变化规律一致。在同类化合物中,铯和钡均是最有效的助剂,钡比铯具有更强的促进作用。以硝酸钡和硝酸铯制备双助剂Ru C催化剂,先钡后铯分步浸渍制备钌催化剂的活性不仅明显高于钡、铯共浸渍钌催化剂,而且也高于先铯后钡分步浸渍钌催化剂。更多还原

【Abstract】 A series of alkaline or/and alkalineearthpromoted, carbonsupported ruthenium catalysts have been prepared N2 physisorption, CO chemisorption and Xray diffraction were carried out to investigate the effect of promoter on the surface area, pore size distribution and ruthenium dispersion of catalysts The activities of the series catalyst for ammonia synthesis were measured under the reaction condition 430?℃, 100?MPa and 10?000?h-1 It has been found that the effectiveness of alkaline or alkalineearthpromoter is roughly related to the basicity of alkaline metal hydroxide or alkalineearth metal oxide For the singlepromoted Ru/C catalyst, cesium and barium proved to be most effective in the alkaline and alkalineearth promoter Bariumpromoted Ru/C catalyst was more effective in ammonia synthesis than cesiumpromoted Ru/C catalyst Barium was suggested to have a stronger interaction with the Ru surface than cesium For the doublepromoted Ru/C catalyst, the activity of the catalyst was affected remarkably by the method of preparation Barium and cesium promoter in 4?w% RuBaCs/C were impregnated by two steps method, barium was impregnated first, after reducing treatment at 400?℃, cesium was impregnated again The catalyst of 4?w%RuCsBa/C was prepared from impregnating cesium first barium later by two step impregnation The catalyst of4?w% Ru(Ba+Cs)/C was prepared from coimpregnation the mix aqueous solution of barium and cesium by one step method The result showed that the activity of 4?w% RuBaCs/C was higher obviously not only than 4?w%Ru(Ba+Cs)/C, but also than 4?w% RuCsBa/C Because barium and cesium competed adsorption during theprocess of preparing the doublepromoted Ru/C catalyst, that would influence the surface distribution of barium and cesium promoter and ammonia synthesis activity of the Ru/C catalyst更多还原