Study On Preparation And Application Of Cog Methanation High-temperature Catalyst

Coke oven gas(COG)is a by-product of the coke-making process,converting COG into more energy-valued products can significantly enhance the energy efficiency,and catalytic co-methanation of CO and C02 in COG may be a high-usage approach with energy utilization rate is as high as 85%,and is an effective way to make up for China's natural gas supply shortage.Methanation catalyst has been recognized as the most important part in the process of COG to LNG We studied the preparation process,calcination conditions and reduction conditions of high temperature methanation catalyst prepared by coprecipitation method by combined with coke oven gas LNG technology and our company methanation catalyst development status.25wt.%Ni/MgO-Al2O3 catalysts were prepared by coprecipitation method,The effect of precipitation temperature from 22 to 95?,end pH 8.5-10.0,aging time for 0-4h factors for the activity and stability were investigated,The as-prepared catalysts were characterized using N2 physical adsorption,chemical adsorption,XRD and ICP(to testing metal content in filtrate).Results show that 80? prepared catalyst has the best low temperature activity and high temperature stability,Ni were existed in the form of highly dispersed amorphous NiO and NiAl2O4,there that is a strong interaction with the carrier.After reduction the catalyst has the smallest size of Ni and the highest specific surface area.PH=9.5 catalyst has the worst activity and stability because of its lowest surface area and largest reduction grain size of Ni.The lengthened of aging time has no obvious effect on improving the activity and stability of the catalyst.We final choose 80?,PH=8.5,aging 0 hour as precipitation conditions.Investigated the effects of reaction time,reaction temperature and instability operation of catalysts,found that the improved process of catalyst has better activity,high temperature stability and resistance to carbon deposition and thermal stress tolerance and mechanical strength than unimproved one,and activity,stability and resistance to carbon deposition is not worse than the foreign commercial catalyst,but the thermal stress tolerance and strength is slightly worse.Catalysts with different calcination temperature(850-1050?)and different time(1-12h)were prepared and activity evaluated.The as-prepared catalysts were characterized by N2 adsorption,chemical adsorption,XRD and strength test,results show that as long as the catalysts had been good reduced,The effect of calcination conditions on the catalysis activity was not obvious,all of these catalysts have good low temperature activity and high temperature activity and stability for 45 hour tests.We found that catalysts had minimal strength at 910? with different calcination time.The crystallinity is pour at 850-910?,and from 950? to 1050? the increase of temperature and the calcination time was beneficial to the formation of spinel.Considering of pore structure and reducing property,we choose 950?,1-5h as roasting conditions.Effect of reduction condition(650-800? and 4-48h)on the catalyst strength,crystal structure and reduction degree were investigated in this paper.The results show that with the increasing of reduction degree the catalyst strength is lower,the Ni grain size is sensitive to temperature but not to time,and reduction did not cause the catalysts' two time sintering,the reduction efficiency of catalysts under 800? was better than others.The increasing of reduction time can improve the reduction degree of catalysts,but after a certain period of time,the lengthen of reduction time had nothing to do with reduction degree.