【摘要】 以K₂RuO₄为钌前驱体,通过共沉淀法制备了Ru/MgO-CeO₂氨合成催化剂。考察了5种不同沉淀剂对Ru/MgO-CeO₂催化剂的结构和性能的影响,并运用X射线衍射（XRD）、CO吸附、N₂物理吸附和H₂程序升温还原（H₂-TPR）等技术对催化剂进行了表征,讨论了沉淀剂对氨合成催化剂结构和性能的影响。结果表明,在450℃、10 MPa和10 000 h^-1条件下,以NH₄HCO₃和（NH₄）₂CO₃为沉淀剂制备的催化剂活性较好,其中,以NH₄HCO₃最好,在无添加助剂的情况下,出口氨浓度为15.91%,而采用KHCO₃、K₂CO₃和KOH为沉淀剂制备的Ru/MgO-CeO₂催化剂氨合成活性相对较低。Ru/MgO-CeO₂催化剂较好的氨合成性能归因于较高的钌分散度和较大的催化剂比表面积,以及较易的钌和载体MgO-CeO₂表面氧的还原程度。更多还原

【Abstract】 Ru/MgO-CeO₂ catalysts for ammonia synthesis were prepared by co-precipitation method using five precipitants,NH₄HCO₃, （ NH₄ ）₂CO₃, KOH, KHCO₃ and K₂CO₃. The influence of different precipitants on the structure and properties of Ru/MgO-CePO₂ catalysts was investigated. The catalysts were characterized by X-ray diffraction （XRD） , CO chemisorption, temperature-programmed reduction of hydrogen （H₂-TPR）. The results indicated that Ru/MgO-CeO₂ catalysts using NH₄HCO₃ and （NH₄ ）₂CO₃ as the precipitants and K₂ RuO₄ as the precursor exhibited high activity for ammonia synthesis under the reaction condition of 450 ℃, 10 MPa and 10 000 h^-1, and the catalyst using NH₄HCO₃ as the precipitants had the highest activity; without the addition of the assistant, ammonia concentration in outlet was 15.91%. Ru/MgO-CeO₂ catalysts using KHCO₃, K₂CO₃ and KOH as the precipitants possessed relatively lower activity of ammonia synthesis. The high catalytic activity of Ru/MgO-CeO₂ catalysts at low temperature for ammonia synthesis was attributed to higher dispersion of ruthenium particles and larger BET surface area of the catalysts, and easier reduction of surface oxygen of MgO-CeO₂ support and ruthenium.更多还原