The Study Of Biomass In-situ Catalytic Cracking And CO₂ Capture For Rich Hydrogen

Biomass is a kind of renewable and clean energy.Biomass gasification is one of the main direction of biomass energy widely used.But in the using process of biomass gasification it still exists two problems:one is the tar produced following with the biomass gasification easily adhere to ash,thus affect continuous production of biomass gasification process and lower its gasification efficiency;the other is the concentration of effective gas component(H2,CO)in the pyrolytic gas produced using air as gasification medium is low,which lead to its application limited.According to above questions,this paper puts forward the topic of biomass in-situ catalytic cracking and CO2 capture for rich hydrogen gas,and carries out the following research on the basis of literature rewiew:1.Using biomass sawdust as the research object,investigates the effects of sawdust pyrolysis gasification and in-situ catalytic cracking on gas components,gas production,contents of tar in gas and the carbon deposition conditions on catalyst.The experimental results show that:when the gasification agent is air medium,air-fuel ratio is 0.23,gasification temperature is 600 ? to 750?,2%(w)catalyst cobalt is added to the sawdust,the exit gas components concentration(mol ratio)are:23%of H2,21%of CO and 4%of CH4,respectively.fuel gas yield is 1.537 Nm3/kg sawdust;the GC-MS analysis results of lotion collected by washing in Cold hydrazine show that it hardly exist tar components;at last,the catalysts before and after usage are compared and analyzed by XRD and SEM.2.Explores the effect of sawdust pyrolysis gasification on gas components when only exists CO2 capture.The experimental results show that:when the gasification temperature is 700 OC,sawdust mixed with CaO in the mass ratio of 7:1 for gasification,in the produced gas,H2 volume percentage can be as high as 26.89%.CO can be as high as 27.00%.CO2 can be as low as 10.34%.Gas production rate is 0.3901 Nm3/kg biomass.CaO has obvious in-situ CO2 capture effect from the XRD characterization analysis.CO2 capture rate can be as high as 47.5%by the thermal analysis.Compared with pure sawdust without CaO pyrolysis gasification,the tar produced in the process of sawdust with CaO gasification has a part of being catalytic cracked.When we do GC-MS analysis to the collected lotion from cold hydrazine gas bottle,we found the tar composition and content are both decreased.3.In the process of biomass gasification,two kinds of by-products,tar and high concentration of CO2 will be produced at the same time.Thus,the forth chapter of this paper studies the tar produced by biomass pyrolysis in-situ catalytic cracking and CO2 capture.The experimental results show that:when adding calcium oxide capture and cobalt catalyst at the same time,physical blending will lead to catalyst deactivation.But when doing experiments using cylindrical composite catalyst which is made by extrusion molding of CaO and cobalt catalyst under the action of a small amount of water,we find that its ability of catalytic pyrolysis tar and absorbing CO2 is obvious.H2 volume percentage can be as high as 23.5%.The content of the combustible gas H2,CO,CH4 is largest,which can be as high as 47.75%.