Research On The Bio-oil From Rice Straw By Microwave-assisted Pyrolysis And Porous Ceramic Materials

As one of the most promising energy substitutes for petroleum in the world,biomass energy is wide available,renewable,clean?low sulfur and nitrogen content?and low emission of greenhouse gas.There are many methods of producing biomass energy,microwave-assisted catalytic fast pyrolysis?MACFP?is one of the best ones.In this paper,green chemicals and materials produced by MACFP with porous ceramic materials doped with rice straw ash heavy metals as catalysts were studied.The effects ofthe carbon to hydrogen ratio,rice straw microwave dry torrefaction and the heavy metal element doped porous ceramic absorbents on the rice straw biooil and rice straw based porous ceramic absorbent properties were investigated.In terms of the effective carbon to hydrogen ratio regulation:mixing with rice straw and low cost hydrogen rich materials such as plant oil soapstocks could increase the effective hydrogen index and produce high quality bio-oil.The microwave-assisted catalytic fast pyrolysis of rice straw and soapstocks for bio-oil production was studied.The results showed that with the addition of the soapstocks,the content of oxygen containing compounds in the bio-oil were decreased while the content of aromatic compounds were increased significantly.Besides,the use of catalyst and the change of temperature had significant effects on the quality of bio-oil.The proper temperature can increase the yield of bio-oil and the proportion of aromatic compounds in the bio-oil;the use of catalyst would reduce the bio-oil yield but it could increase the aromatic compounds and improve the value of the bio-oil.When the pyrolysis temperature was 550?,the catalyst to feed ratio was 1:2,and the rice straw to soapstocks ratio was 1:1,the yield of bio-oil could reach 42.32 wt%,with the proportion of aromatic compounds in bio-oil of 33.32 wt%.In terms of the microwave torrefaction pretreatment:it could be used as an effective pretreatment method to improve the properties of rice straw,reduce the content of oxygen and improve the quality of the bio-oil.The effects of microwave torrefaction pretreatment on the bio-oil from co-pyrolysis of rice straw and soapstock were carried out.The results showed that the content of oxygen in the rice straw was decreased dramatically after the microwave torrefaction,and the effective hydrogen index was further increased when the torrefied rice straw was mixed with the soapstocks.At290?and 15 min,the oxygen content of rice straw decreased from 43.99 wt%to35.69wt%,while the effective hydrogen index increased from 0.135 to 0.4375.During the co-pyrolysis test,microwave torrefaction could reduce the yield of bio-oil,but it could reduce the content of oxygen containing compounds.Meanwhile,the content of aromatic compounds in the bio-oil would increase,and the quality of the bio-oil was improved.In addition,the addition of Mg?OH?₂ in the process of microwave torrefaction could further enhance the effect of torrefaction and reduce the oxygen containing compounds in bio-oil effectively.The oxygen containing compounds decreased from 21.25 wt%to 15.93 wt%.For the evaluation of the heavy metal doped porous ceramic material:the red soil from Jiangxi was selected to be the main raw material,the waste glass was used as the flux and the rice straw for the pore formation.When the temperature was 800?,the additive amount of the rice straw was 10%,the residence time was 1 h,and the waste glass to red soil was 4:6,the porous ceramic material had high porosity,high hardness and good bulk density.In the subsequent adsorption test,the porous ceramics had a good adsorption capacity for Cd²⁺in water.It can adsorb a large amount of heavy metals in a short time.When the concentration of Cd²⁺in wastewater was 50mg/L,the adsorption rate of heavy metal cadmium by 10 g porous ceramic balls could reached nearly 100%.Therefore,it could be used as a heavy metal absorption material in life.