A New Process Research Of Biomass Syngas Methanation

The characteristics of resource distribution in China is "rich in coal, poor in petroleum, lack of gas". Coal as main fuel, serious pollution of its consumption has greatly restricted its development. With rapid economic development, new type of energy is in need. Therefore the development of environmentally friendly renewable energy has been the international challenge of the world.China is an agricultural country with abundant biomass resources, but most of the biomass resources are used as fuel, which is a great waste because of its low thermal efficiency and serious haze pollution. How to make reasonable use of biomass energy has raised widespread concern. Biomass can be transformed into syngas which can be used as chemical raw materials and fuel gas. Nowadays the syngas in our country contains more than 20% percent of CO which is far more than the national standard that the CO content of civil gas should be less than 10%. CO and H2 can be synthesized into methane by methanation reaction. By this procedure, the content of CO is reduced and the product CH4 is a clean energy of high calorific value. So methanation reaction upon biomass syngas is an economic and convenient route.In this paper, Ni-based catalyst was compounded. And the catalyst activity was studied under the condition that H2/CO molar ratio is 3/1. And the influential factors such as precipitant, reduction temperature and space velocity were also discussed in this paper. Result showed that 8NiO/?-Al2O3 catalyst prepared by urea precipitation load method has the best catalyst activity. CO conversation can be up to 100% and the CH4 yield can be above 95% under the condition of reduction for 3 h under 500 ??space velocity 10000~15000h-1?reaction temperature 350 ?. The performance of this catalyst is basically consistent with the commercial catalyst that has a NiO content of 18%.The low H2/CO ratio in biomass syngas influences the methane yield. So in this paper water-gas shift reaction and CO methanation reaction were coupled together in order to improve the H2/CO ratio in the reaction system. The catalyst type, space velocity, reduction temperature, water amount, grain filling degree, grain size and other factors were examined. The experimental results showed that Cu-Zn as catalyst, quartz sand as the diluent and the catalyst/diluent mass ratio 1/2, water amount 0.02 mL/min in the water-gas shift reaction stage; while space velocity 15000h–1, reduction temperature 450 ?, catalyst granularity 40-60 mesh in the methanation reaction, the commercial methanation catalyst with 18% of NiO exhibited the optimal performance. The CO conversion reached to 100% which meets the demand of national standard of civil gas. The study in this paper has significant importance of improving the efficiency of biomass resources and alleviating the energy and environmental crisis.