Preparation Of Syngas From Straw Pyrolysis And Catalytic Reforming And Its Thermodynamic Characteristics

The environmental problems caused by the massive consumption of fossil energy have become increasingly serious,and renewable energy such as biomass energy has become a research hotspot.China is a big agricultural country.With the increase of grain production,a large amount of straw is not used reasonably every year.The use of straw to prepare syngas and subsequent synthesis of chemical products can alleviate the dependence of chemical products on petroleum and other non-renewable energy sources.In this paper,four different catalyst supports(?-Al2O3,TiO2,SiO2,ZSM-5)with different loadings(5%?15%)of nickel-based catalysts with 3%Cu as auxiliary were prepared by the same volume impregnation method.A closed cycle device was designed to evaluate the catalyst activity and the catalytic reforming characteristics of corn straw pyrolysis gas.The catalytic reforming process was numerically simulated.The effects of the type of catalyst carrier,loading capacity,mass ratio of catalyst to corn straw(C/B),temperature(pyrolysis temperature and catalytic reforming temperature)and mass ratio of steam to corn straw(S/B)on the catalytic reforming of corn straw pyrolysis gas were experimentally investigated.The thermodynamic equilibrium method was used to establish a model for the preparation of syngas by pyrolysis catalytic reforming of straw,and thermodynamic analysis was carried out.The calculated results agree well with the experimental results.Predictive analysis has certain scientific guiding significance for the experiment.The result shows:The type and loading of the catalyst carrier will have a certain effect on the activity of the nickel-based catalyst.In the four carriers of activated alumina,titanium oxide,silica and molecular sieve,the loading is in the range of 5%to 15%,with activated alumina as the carrier the nickel-based catalyst with 10wt%loading has better activity,and the prepared syngas has a higher content of active ingredients and less greenhouse gas content.When C/B=0.5,S/B=1,pyrolysis temperature and catalytic temperature are both 850?,the content of active ingredients in the syngas is higher,H2 content is 47%,CO content is 33%,and the greenhouse gas content is lower.The content of CO2 is 12%,and the content of CH4 is 5%.The gas production rate is 1.16Nm3/kg,the gasification efficiency is 87%,and the carbon conversion rate is 70%.A thermodynamic equilibrium model for straw catalytic reforming is established.After considering the deviation of the methanation reaction equilibrium and the modification of the experimental device,the gas composition after catalytic reforming of straw pyrolysis gas can be accurately predicted using a simple thermodynamic equilibrium model.The model calculation results show that the increase in S/B increases the water-gas reaction,leading to a rapid increase in CO2 content while a rapid decrease in CO content.Increasing the temperature of the pyrolysis furnace is conducive to the generation of hydrogen.The increase in the temperature of the catalytic reforming furnace is beneficial to the reduction of greenhouse gas(CO2 and CH4)content.