Experimental Study On Biomass Microwave Cracking

In this thesis,the pyrolysis of biomass is studied in a microwave cracking reactor.The dissertation comparatively studies the microwave cracking process under different atmosphere conditions.The influence of the catalyst on the cracking products and the cracking rules of different kinds of raw materials are investigated.This study provides a theoretical basis for the microwave cracking of biomass.The dissertation comparatively studies the microwave cracking process under N2 and CO2 atmosphere.Under the N2 atmosphere,the main components of the liquid product pyrolysis oil are phenols and esters,which accounted for 27.7%and 34.5%,respectively,and the specific surface of the solid product coke is 125.44m2/g.Under the CO2 atmosphere,the content of esters in the liquid product cracking oil decreases to 4.6%,the content of phenols increases to 41.5%,and the specific surface area of the solid product coke increases to 136.85 m2/g.Under CO2 atmosphere,the effects of four catalysts(KCl,KH2PO4,Ca(OH)2,Na2CO3)on microwave pyrolysis are investigated.The study shows that Ca(OH)2 has the best catalytic effect and the yield of cracked oil is 41.24%.The acidity and alkalinity of the catalyst have a certain influence on the pH of the pyrolysis oil.Ca(OH)2 and Na2CO3 are favorable for reducing the acidity of the pyrolysis oil.After the sawdust is treated with acid,the components of the liquid product cracking oil are reduced,the furfural and ethyl citrate contents are 14.8%and 14.3%,respectively,and the specific surface area of the solid product coke increases to 178.52 m2/g.After alkali treatment,the phenolic content of the liquid product cracking oil increases by 29.9%to 53.9%.Under CO2 atmosphere,different kinds of biomass raw materials are studied.Studies have shown that the content of phenols in the microwave pyrolysis oil of soybean stems and bamboos accounts for about 40%,the phenols in peanut pyrolysis oil accounts for 23.81%,and the acids in rice husk pyrolysis oil reaches 25.37%.In addition,as the power increases,the C/H and C/O ratios in the coke decrease,the aromaticity and polarity of the coke increase,and the specific surface area of the coke increases.