Steam Gasification Of Sawdust For Hydrogen Production And The Gasification Residue Used For Methane Conversion

As the reducing traditional fossil energy sources and the increasing environmental pollution caused by the use of fossil energy,it is extremely urgent to seek for a new renewable energy source.Hydrogen is a clean secondary energy with the potential to partially replace fossil fuels.Currently,biomass gasification and methane thermal cracking are two hydrogen production technologies with good future prospects.Based on this,the work proposes and develops a process for hydrogen production by utilizing biomass gasification residue for methane cracking/reforming.By selecting and regulating the biomass gasification conditions,a high-efficiency catalyst for methane decomposition/reforming reaction can be designed and prepared.The formation of the biomass gasification-methane conversion poly-generation process can enhance the utilization efficiency of the metal catalyst components.In this paper,pine sawdust was selected as biomass raw materials.Firstly,the performance of hydrogen production from steam gasification of pine sawdust was investigated.The results showed that a higher hydrogen production can be obtained(about 50 mmol/g_ps)when the steam flow rate was 0.252 mol/min,the reaction temperature was 650?,and the mass ratio of pine sawdust/Ni was 1:0.08.By selecting and controlling the gasification reaction conditions?temperature,mass ratio of pine sawdust/Ni,steam flow rate and gasification time?,nickel particles highly dispersed on Ni/carbon composite catalyst can be prepared in situ with high activity and stability in methane cracking reaction.For example,after 600 min of methane decomposition reaction,the methane conversion rate can be still above 90%,and co-production of hydrogen and carbon fiber can be also achieved.This method of in-situ synthesis of Ni/carbon catalysts by selective gasification of pine sawdust provides a new idea for the design and preparation of novel catalysts.Subsequently,the performance of the above Ni/carbon composite catalyst was studied in methane carbon dioxide reforming reaction.It is found that the above Ni/carbon composite catalyst has poor catalytic performance but its catalytic activity and stability can be significantly improved by regulating its specific surface area or introducing additives.When CeO₂ or MgO is introduced as an auxiliary,the specific surface area of the Ni/carbon composite catalyst can be improved,and in the methane carbon dioxide reforming reaction the methane conversion?above 60%?and carbon dioxide conversion?above 70%?can be increased.When MgO is used as a carrier and Cu as an auxiliary agent,it is intetresting that co-production of synthesis gas and carbon fiber can be obtained in the methane carbon dioxide reforming reaction.