Study On Methanation Reaction From Syngas Over Ni Based Catalyst

The syngas methanation reaction has been paid attention as one of the keytechnologies of coal to gas recently. Developing a catalyst with high activity, highselectivity and high stability is of theoretical significance and application value. Thecatalytic performances of Ni based catalysts with varied ZrO2contents in compositesupport, Ni loadings, promoters in the syngas methanation reaction were studied;besides, their stability performance, accompanying with the effect of reaction processconditions on the catalytic behavior of catalysts were also investigated. The catalytictest was carried out in a fixed-bed reactor under T=300~650℃, P=0~2.0MPa (gaugepressure), GHSV=5000~15000h-1and H2/CO=1~3. The catalysts were characterizedby N2adsorption-desorption, X ray diffraction (XRD), H2temperature programmedreduction (H2-TPR), H2chemisorption, thermogravimetry (TG) and scanning electronmicroscope (SEM). The main contents and results are as follows.(1) The effects of ZrO2contents and Ni loadings are investigated. The resultsshowed that the catalyst with Ni loading of20wt%and ZrO2content of40wt%exhibits the highest catalytic performance. The stability results and the extensivecharacterizations revealed that the addition of ZrO2remarkably promotes the stability,the anti-carbon deposition and anti-sintering performance of catalyst.(2) The Ni/ZrO2-Al2O3catalysts were promoted by different promoters (La, Coor Nb) with varied contents. The results revealed that the addition of La significantlyimproves the performance of catalysts. When the added La content is4wt%, thecatalyst displays the highest catalytic performance with excellent stability. Thecharacterization results showed that the catalyst contains less carbon deposition, andNi crystallite size displays little change after the stability test.(3) The effects of reaction process conditions on the modified catalyst werestudied. The results showed the catalyst is able to behave high catalytic performancewithin the reaction conditions of T=300~500℃, P=0.5~1.5MPa (gague pressure),H2/CO=2.5~3.0, SV=8000~15000h-1and CO2content <20vol%.