Ni-based catalysts for methanation were prepared by three different precipitants: urea, ammonium carbonate, ammonia and their activities were investigated under different conditions. The characterization of the catalysts were determined by XRD, H2-TPR, BET and TPO. Based on the results, the catalysts prepared by different methods of precipitation exhibited different catalytic properties: the surface area of the catalyst prepared by using urea reached up to 223.55 mVg, which suggested an stabilized catalytic activity; the catalyst prepared by ammonium carbonate precipitant had larger size particles, non-uniform distribution and more carbon deposition; the catalyst prepared by ammonia precipitant possessed smaller particle size,stronger interaction with support,but the loss of active components was more serious especially at high temperature. It was indicated that the precipitants mainly affected the shape and inner structure of the catalyst precursors,resulting in different fields of dispersion, crystal structure and hydrogen adsorption capacity. Thus, the activities and stabilities of the catalysts were different.%利用尿素、碳酸铵、氨水三种沉淀剂制备了不同的镍基甲烷化催化剂,考察了沉淀条件对催化剂性能的影响.通过XRD、H2-TPR、BET、TPO等方法对催化剂进行表征.结果表明,使用不同沉淀剂所得催化剂性能各不相同.采用尿素沉淀剂,颗粒的比表面积达到了223.55 m2/g,具有较稳定的催化活性；碳酸铵沉淀颗粒粒径较大,分散也不够均匀,催化剂更容易积炭；氨水沉淀制备的催化剂粒径小,与载体结合性强,高温下活性组分易于流失.分析认为,沉淀剂影响了催化剂前驱体的形态和结构,造成了分散度、晶相结构、对氢的吸附性质以及抗积炭性等多方面的差异,表现出甲烷化反应活性和稳定性的不同.
展开▼
