Optimization And Mechanism Study Of Catalytic Pyrolysis Process Of Typical Invasive Plants Based On Feedstocks Regulation

Since the 21 st century,with rapid global economic growth and industrial development China is facing many energy-related challenges,mainly including the depletion of traditional fossil fuels(oil,coal,and natural gas),and a series of environmental pollution problems such as "acid rain" and "greenhouse effect".In September 2020,China solemnly proposed that China will realize peak carbon dioxide emissions before 2030 and strive to achieve carbon neutrality before 2060.In this context,to solve the increasingly serious energy and environmental problems,Central Document No.1 claimed that it is required to vigorously make full use of biomass resources and achieve the carbon peak and neutrality targets as soon as possible.According to the current biomass utilization methods,this paper conducts a systematic optimization study on the fast catalytic pyrolysis of biomass from the perspectives of biomass pretreatment technologies and hydrogen donors.Hope to find the best proceeding to improve the efficiency of the pyrolysis process and increase the yield of monocyclic aromatic hydrocarbons.Moreover,the mechanism and possible reaction paths of the synergistic effect in the catalytic pyrolysis process are mentioned.The details are as follows:Study on the influence of Fenton-like pretreatment on the microstructure and functional group characteristics of water hyacinth: First,the Center Combination Design(CCD)method is used to design different Fenton-like pretreatment conditions,and X-ray diffraction(XRD),Scanning Electron Microscope(SEM)and Fourier Transform Infrared Spectroscopy(FTIR)and elemental analyzers are used to observe the microstructure and functional group characteristics of biomass before and after pretreatment,the results show that Fenton-like pretreatment can effectively enhance the content of C,H,the value of C/O and calorific.For the internal microstructure of water hyacinth,Fenton-like pretreatment improves the crystallinity and the accessibility of cellulose,so that different degrees of pores and bubbles appear on the surface of water hyacinth,effectively changing the original lignin structure and enhancing the relative content of cellulose.Study on the effect of Fenton-like pretreatment conditions and HZSM-5 catalyst on the pyrolysis products derived from water hyacinth: The effects of different Fenton-like pretreatment conditions and HZSM-5 catalysts on the pyrolysis characteristics of water hyacinth are investigated by Py-GC/MS and response surface methodology.The results show that after Fenton-like pretreatment,the yield of the esters and phenols in the pyrolysis products decreases,correspondingly the contents of hydrocarbons and sugars increase.While the contents of ketones,aldehydes,and furans are not significantly affected by Fenton-like pretreatment.However,the application of Fenton-like pretreatment promotes the yield of hydrocarbons,monocyclic aromatic hydrocarbons,and sugars in the catalytic pyrolysis products of water hyacinth,while inhibiting the formation of acids and phenols.Study on the mixing ratio of hydrogen-rich substances and HZSM-5 catalyst to control the fast pyrolysis characteristics of water hyacinth: The water hyacinth and hydrogen-rich substance HDPE are pyrolyzed with different mixing ratios at different heating rates.Thermogravimetric analyzer is used to investigate the influence of the mixing ratio of HDPE and water hyacinth on the kinematic properties during the biomass pyrolysis process.The results show that when the heating rate is low,the condition may induce more side reactions due to insufficient heat supply,and the high heating rate can reduce the pyrolysis efficiency.The addition of HDPE to the pyrolysis feedstocks can reduce the formation of coke,increase the value of CPI,and shorten the pyrolysis time.The mixture sample with the mixing ratio of3:1 shows the strongest synergistic effect during the co-pyrolysis process,and the difference between the experimental weight loss and the theoretical weight loss was negative.This difference is more notable in the presence of the HZSM-5 catalyst.The activation energy of the feedstock with the mixing ratio of 3:1 is lower than that of the other blends.Similarly,the addition of HZSM-5 catalyst in the mixed pyrolysis process can enhance the synergy between water hyacinth and HDPE.The activation energy required by the mixed raw materials in the pyrolysis process decreases with the increase of the mixing ratio,and the addition of HZSM-5can further reduce the required activation energy for the reaction.The free radicals generated during the catalytic pyrolysis of the raw materials are mainly methyl radicals.Catalytic copyrolysis of water hyacinth and HDPE produced methoxy free radicals and more different kinds of free radicals,which may be the inducing substances to promote the synergistic effect of water hyacinth and HDPE.