Study On The Pyrolysis And Catalytic Pyrolysis Behaviour Of Rape Straw

The pyrolysis is a hot technology that efficiently converts widespread and cheap biomass resources into high quality and easy-to-store bio-oil.The pretreatment of biomass feedstock before pyrolysis and the addition of catalysts in the pyrolysis reaction are important methods to improve the yield and quality of pyrolysis liquid.In this paper,rape strew(RS)was taken as the research object.The effects of temperature,N2 carrier gas flow rate,acid and organic solvents treatment and the developed oxides and a series of Fe/HZSM-5 catalysts were investigated by using fixed-bed reactor,TG-FTIR combined with GC-MS on the composition and distribution of RS pyrolysis production,and the development of physical and chemical structure of catalysts was characterized by BET,XRD,NH3-TPD,SEM and so on.The effects of different process conditions(temperature and carrier gas flow rate)and the acids and organic solvents treatment of RS on the distribution of pyrolysis products were investigated by a fixed-bed reactor.The results found that the higher the temperature,the higher the liquid and gas yield,the lower the solid yield.And the liquid yield reached 41.92 % at 500 ?.When the flow rate of N2 is 50 m L/min,the yield of liquid was lower,because the lower carrier gas flow made the evacuation gas stay longer at the heating temperature for secondary cracking.Through the pretreatment of RS,AAEMs could be effectively removed,the yield of liquid might be increased,and the content of aliphatic hydrocarbons,aromatics and sugar in the bio-oil increased in some extend,ketones,phenols and nitrogen-containing compounds decreased significantly.Thermo-gravimetric(TG)combined with Fourier Transform Infrared(FTIR)technique was used to simultaneously detect pyrolysis process.The TG experiment results showed that the residual coke content in the final temperature decreased and the curve shifted to the high temperature region,HCl+HF resulted in the greatly decrease of the weight loss rate,whereas the pretreatment of organic solvent improved.The results of FTIR found that the pretreatment technology reduced the release of CO,CO2,CH4 and H2 O from RS pyrolysis.Different zeolites were used to investigate the effect of physical and chemical structure on the distribution of RS pyrolysis products.It was found that the yields of pyrolysis production increases or decreases.And H-Beta and ZSM-5 with high Si/Al ratios were favorable for liquid formation(39.61 %).The metal oxide catalysts were prepared to investigate its effects on the distribution and compositions of RS pyrolysis products.The results showed that the metal oxide catalysts could improve the pyrolysis liquid yield,of which Ti O2 showed good catalytic activity,and the liquid yield was up to 40.60 %.The content of aliphatics and aromatics,furans compounds in the bio-oil was increased,whereas aldehydes,ketones,phenols and carbohydrates were reduced.TG-FTIR results showed that the addition of metal oxide catalyst inhibited the decomposition of macromolecules and reduced the weight loss rate of pyrolysis.Ti O2 was conducive to the generation of CO,H2 O and CO2.The addition of Al2O3 promoted the evolution of CH4 gas,and Zr O2 could reduce the escape of H2 O,CH4 and CO2.The catalysts which were composites of zeolite and oxide could improve the yield of pyrolysis liquid,where in the optimum mass ratio of 0.01:1 increased the liquid yield up to 40.28 %.To explore the loading of active metal Fe,the type of solvent,the pretreatment of zeolite support,the type of complexing agent,the ratio of complexing agent and metal and the different preparation methods in the preparation of Fe/HZSM-5 catalysts on RS pyrolysis product distribution.Some studies on different preparation methods were carried out.The results showed that the weight loss rate and maximum weightlessness rate of samples decreased,while the maximum weightlessness rate peaks shifted slightly to the low temperature region.The yield was increased by 2.73 %-5.31 %,and the Fe/HZSM-5 catalyst prepared by complexing method obtained the highest liquid yield of 41.00 %.Compared with HZSM-5,the Fe/HZSM-5 series catalyst reduced the char yield by 2.32 %-12.8 %,and the maximum extent of gas could be increased by 6.42 %.It did promote the formation of aliphatics,aromatics,furan and N-compounds,inhibite aldehydes,ketones,phenols,alcohols and carbohydrates.