Influence of precipitant on the performance of nickel catalyst for methanation

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 223.55m²/g,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.