Research On Methanation Catalysts Prepared By Solution Combustion Method

Natural gas is regarded as a clean energy source due to its advantages:clean and high calorific value.However,the consumption of natural gas is growing with the speeding up of industrialization and urbanization,and the implementation of the policy of energy conservation and emissions reduction in China.The energy structure in China is poor in natural gas,but rich in coal.Producing synthetic natural gas(SNG)through syngas methanation will become an efficient way to make up for the shortage of natural gas in our country.As for syngas methanation,catalysts are the core technique.Thus,developing highly efficient methanation catalysts is significant to relieve the energy crisis.Taking the intensely exothermic character of methanation and the cost into consideration,Ni-based catalysts are the most widely used catalyst.This paper focused on the effects of different solvents,Zr promoter,Ce promoter and Sm promoter on the textural properties,reduction properties,adsorption capacity and catalytic performance of Ni/?-Al2O3 catalysts.The effect of solvents on catalystic performance was investigated.Ni/?-Al2O3 catalysts were prepared by SCM in different solvents(i.e,ethanol,glycol and diethylene glycol).The results showed that solvents significantly affected the textural properties of the catalysts.Catalysts prepared by diethylene glycol had smaller Ni particles and more active sites,which enhanced the catalytic performance.Zr and Ce doped Ni/?-Al2O3 catalysts were prepared by solution combustion method for CO methanation.Compared to single promoter doped catalysts,Zr and Ce modified catalysts exhibited higher activity.Particularly,catalyst with 4 wt%Zr and 2 wt%Ce(Ni-4Zr2Ce)reached almost 100%CO conversion and 96.7%CH4 selectivity at 240 ?,2.0 MPa,and a WHSV of 12000 mL·g-1·h-1,and showed good stability at 600?.Ce and Zr could weaken the interaction between NiO and support,thus restrained the formation of NiAl2O4 spinel phase and improved the Ni dispersion.Compared with single promoter catalysts,Zr and Sm dual promoters catalysts weaken the interaction between Ni and support,which restrained the formation of NiAl2O4 spinel phase.There were more active sites in dual promoters catalysts for the smaller Ni particles,which could improve CO adsorption capacity,facilitating CO methanation.Ni-2Zr2Sm exhibited the low-temperature catalytic activity with a CO conversion of 99.8%and CH4 selectivity of 98.8%at 280?;and also showed good stability during a 50h stability test.