Study On The Pyrolysis And Catalytic Pyrolysis Behavior Of Cellulose

In this paper,microcrystalline cellulose?MCC?was used as a catalytic pyrolysis material to investigate its catalytic pyrolysis behavior.On the one hand,using different potassium salts as catalysts,the metal potassium and negative ions were supported on the surface and inside of MCC by impregnation method to study the effect of synergistic action of potassium and anions on the upgrading of MCC pyrolysis bio-oil.On the other hand,the effect of the catalyst on the yield of MCC pyrolysis bio-oil and the effect on the quality of bio-oil were analyzed by using supported molybdenum carbide as catalyst.In this paper,fixed-bed pyrolysis,TG-FTIR,GC/MS and other characterization methods were used to characterize MCC and bio-oil before and after treatment,and physical and chemical structure analysis of the catalyst was carried out by XRD,SEM,BET,NH₃-TPD and so on.The pyrolysis stage of MCC was?250³70??,which was the main stage of MCC pyrolysis.The mass loss of MCC was about 94 wt%,the pyrolysis process became more intense,and the active cellulose and unstable components were thermally decomposed into small molecules.Matter and macromolecules could condense volatile substances;from the FTIR analysis,MCC could produce different macromolecular condensable volatile substances?such as sugars,aldehydes,ketones etc.?during pyrolysis.Alcohols and phenols,etc.and small molecular substances?such as CO,CO₂,H₂O,CH₄,etc.?;GC/MS analysis of bio-oils showed that saccharides were the main products in MCC pyrolysis liquids,and their yield reached 66.21%,and the yield of levoglucosan was 58.19%.Finally,we determined the optimal process conditions for MCC pyrolysis by fixed bed experiments:pyrolysis temperature was 340?,the pyrolysis rate was 10?/min,the carrier gas flow rate was 100mL/min?N₂?,and the retention time was 30 min.Aiming to investigate the synergistic effect of K and anions on the primary products of MCC pyrolysis.KHCO₃,KCl,K₂CO₃ and KOH were impregnated with MCC.The GC/MS and TG-FTIR were used to investigate the volatiles during pyroysis and catalytic pyrolysis,as well as the product distribution of pyrolytic bio-oil obtained from fixed bed reactor,respectively.KHCO₃ was the most effective in producing and upgrading bio-oil,the liquid yield increased from 44.29%?MCC?to 59.27%?0.10 KHCO₃-MCC?,and the yield of furanic compounds?5-Hydroxymethyl furfural,Furfural?and other O-containing compounds increased from 9.88%?MCC?to 19.84%?0.10 KHCO₃-MCC?,18.54%?MCC?to 46.47%?0.10 KHCO₃-MCC?,respectively.The yield of levoglucosan decreased from66.21%?MCC?to 22.95%?0.10 KHCO₃-MCC?.The effect of supported transition metal molybdenum carbide catalyst on the liquid yield of MCC catalytic pyrolysis was explored.The results show that the bio-carbon-supported transition metal Mo2C catalyst modified by metal promoter can improve the bio-oil yield to a certain extent.The bio-oil yield of MCC was 44.29%,the coke yield was 48.23%,and the gas yield was 7.48%.However,the use of alumina-based supported transition metal Mo₂C catalyst increased the bio-oil yield by 6.09%and the coke yield by 5.95%.The gas yield changes little.