Study On The Preparation Of Hydrocarbon-Rich Fuel From Catalytic Pyrolysis Of Poplar And Polyethylene Composites Using Hierarchical HZSM-5

Wood-plastic composite material is widely used as an emerging composite material in indoor and outdoor decoration,automobile accessories and other fields.It has good application prospects,reducing the waste of biomass and plastic waste resources and the pressure on the natural environment.The wood-plastic composite material will generate secondary waste after repeated recycling.The wood-plastic composite material can be converted into a high-quality biofuel through fast pyrolysis liquefaction technology.In this paper,wood/HDPE composites?WPE?were used as wood-plastic composites,and HZSM-5,which is modified after alkali treatment,was used as a catalyst.The research on hierarchical HZSM-5 catalytic WPE pyrolysis to produce high-quality biofuelsHZSM-5 zeolites was selected as the pyrolysis catalyst,and HZSM-5 was treated with NaOH with different concentrations.The purpose was to introduce the mesoporous structure into the microporous HZSM-5 to form a micro-mesoporous hierarchical HZSM-5 molecular sieve.Characterization of HZSM-5 molecular sieves before and after modification was performed by BET,XRD,NH₃-TPD,PY-IR.The results showed that the treatment of HZSM-5 with the appropriate concentration of NaOH did not destroy the framework structure of HZSM-5 molecular sieve.Pore structure,pecific surface area,pore volume,and average pore size were increased.At the same time,the strong acid of HZSM-5 molecular sieve was converted to weak acid,the amount of strong acid decreases,and the amount of weak acid increases.HZSM-5 molecular sieve increased B acid,L acid decreased,the total amount increased.After 0.3mol/L NaOH treatment,HZSM-5 has the best pore structure and calculation characteristics,with a specific surface area of 375.3m²·g^-1,a pore volume of 0.52 cm³·g^-1,an average pore size of 5.52 nm,and a total acid content of 420.70?mol./g,the amount of B acid reached 354.13?mol/g.A self-made catalyst evaluation device was used to perform catalytic pyrolysis experiments on WPE under HZSM-5.The pyrolysis conditions?the HZSM-5 treated with different concentrations of alkali,the amount of HZSM-5 and the pyrolysis temperature?were used to analyze the composition and distribution of WPE catalytic pyrolysis products.It was found that the amount of HZSM-5,pyrolysis temperature,and HZSM-5 treated with different concentrations of alkali had different effects on the composition and distribution of WPE catalytic pyrolysis products.When the alkali treatment concentration is less than 0.3 mol/L,the gas product yield increases with increasing alkali treatment concentration,the solid product yield gradually decreases,and the liquid product yield generally decreases.In the pyrolysis products,the hydrocarbon compounds C6-C7 migrate to C8-C9,the content of benzene and toluene in the aromatic compounds decreases,and the content of xylen e increases.The yield of bio-oil gradually decreases with the increase of the amount of HZSM-5.The bio-oil is mainly based on C7-C8 aromatic compounds,and the yield of aromatic compounds reaches more than 90%.Properly increasing the pyrolysis temperatur e can increase the yield of bio-oil.At the pyrolysis temperature of 550°C,the yield of the liquid product catalyzed by WPE reaches a maximum of 54.55%.Increasing the pyrolysis temperature changed the distribution of C atoms in the hydrocarbons in the p roduct,increasing the content of C10-C15 hydrocarbons,and increasing the content of naphthalenes in the aromatics.The response surface analysis method was used to optimize the optimal pyrolysis reaction conditions?molecular sieve dosage,pyrolysis temperature,and different graded HZSM-5?of WPE catalytic pyrolysis bio-oil yield and monocyclic aromatic hydrocarbon yield.The quadratic regression equations of oil yield and monocyclic aromatic hydrocarbon yield were analyzed by variance to verify the val idity of the equation model.The optimized pyrolysis conditions are:molecular sieve:material is1:1.77,the pyrolysis temperature is 581°C,the selected catalyst is 0.24-HZSM-5,the average bio-oil yield under this pyrolysis condition is 51.25%,and the average yield of the monocyclic aromatic hydrocarbons is 82.89%.