Study On Catalytic Co-pyrolysis Characteristics Of Microalgae And Municipal Solid Waste Based On Zeolite Catalyst

The increasing fossil fuel exhaustion and environmental pollution are inevitably threatening the world development and economic growth.Microalgae is considered to be the raw material for the production of third-generation renewable biofuels.With its excellent bio-oil production capacity,it is expected to solve the problem of energy shortage in the future.In recent years,the output of Chinese municipal solid waste has increased rapidly.If not handled properly,it will not only cause harm to the ecological environment,but also waste its potential for energy production.Pyrolysis technology can achieve the treatment goals of waste reduction,reclamation and harmless utilization,and has a higher energy recovery efficiency than other thermochemical reactions.In order to obtain higher-quality biofuels,the research on the pyrolysis of waste alone tends to develop in the field of catalytic pyrolysis mixed with biomass.Based on the current utilization status of microalgae and MSW at home and abroad,this article aims to produce high-quality liquid fuels by studying the pyrolysis and catalytic pyrolysis of microalgae and municipal solid waste.In this paper,a variety of experimental techniques and methods are used to study the reaction characteristics and the precipitation rules of microalgae and municipal solid waste pyrolysis process,as follows:(1)The pyrolysis characteristics of microalgae,municipal solid waste and their mixed samples were studied using the thermal synthesis analyzer.The pyrolysis initiation temperature,termination temperature,mass residual rate,and maximum weight loss peak temperature of microalgae are all higher than that of municipal solid waste,while the maximum weight loss rate is lower than that of municipal solid waste.After the mixed pyrolysis of microalgae and municipal solid waste,the pyrolysis characteristics of the mixed samples in the main mass loss stage are similar to the superposition of microalgae and municipal solid waste.In the temperature range of 260.0-330.0 ℃,theΔTG curves of all mixing ratios show significant negative peaks,and there is a synergistic effect between microalgae and municipal solid waste.When the mixed ratio of municipal solid waste is50%,the synergy reach the strongest.In the high temperature range,theΔTG curve shows a significant positive peak,showing an antagonistic effect between microalgae and municipal solid waste.(2)The distribution of pyrolysis products of microalgae,municipal solid waste and their mixed samples was studied by the rapid pyrolysis-gas chromatography-mass spectrometer experiment.The experimental results show that the hierarchical ZSM-5 catalyst has the best promotion effect on optimizing product distribution.The catalyst increases the yield of monocyclic aromatic hydrocarbons,which reduces the yield of nitrogen-containing compounds and acids.The best mixing ratios of municipal solid waste are 50% and 70%,both of which can promote the production of monocyclic aromatic hydrocarbons and aliphatic hydrocarbons as the target product.The hierarchical ZSM-5 catalyst modified by Fe and Ni bimetals improves the selectivity of aromatic hydrocarbons of benzene,toluene and xylene,and improves the quality of pyrolysis products.(3)Use nitrogen physical adsorption,scanning electron microscope,X-ray diffraction and other methods to analyze the physical and chemical properties of the ZSM-5 zeolite modified with desiliconization and loaded with metal iron and nickel.The results show that the desilication treatment creates vacancies in the ZSM-5 zeolite crystals and effectively introduces the mesoporous structure.The total specific surface area,total pore volume and average pore diameter of zeolite after desilication are higher than those of ZSM-5 zeolite.The metal loading modification treatment reduces the specific surface area and pore volume of the zeolite,but increases the average pore diameter.The zeolite after desilication treatment and metal modification treatment retains the original ZSM-5 framework structure,and the crystallinity of the zeolite hardly changes.(4)Using the equal conversion rate Flynn-Wall-Ozawa method and Kissinger-Akahira-Sunose method,the kinetic model of mixed catalytic pyrolysis of microalgae and municipal solid waste is established.The results show that with the increase of the mixing ratio of municipal solid waste,the average apparent activation energy of the mixture shows a trend of first increasing,then decreasing and increasing again.The average apparent activation energy is obtained when the mixing ratio of municipal solid waste is70%,which is 207.77 kJ/mol(199.99 kJ/mol).