High-valued Utilization Of Waste Biomass Based On Multi-path Pyrolysis Theory

Faced with new challenges in energy security and carbon peaking and carbon neutrality goals,the high-value utilization of waste biomass has attracted widespread attention from researchers.The development of carbon sequestration materials and the refining of high valueadded chemicals are effective ways to replace fossil-based products.Therefore,based on the multi-stage pyrolysis theory,this paper developed and analysed relevant models from two paths of the high-valued utilization of biochar carbon fixation and the high-valued utilization of multitechnology collaborative negative carbon,with waste cabbage leaves as the raw material.The research contents are as follows:(1)The proposal and validation of multi-path pyrolysis model.In this paper,the product behavior characteristics of waste cabbage were investigated under multi-path pyrolysis mode,and a multi-path product generation model(MPG)was proposed.The results show that the thermochemical conversion of waste cabbage leaves is multi-stage,and the heating rates affect the ease of the conversion process.The average activation energies estimated via KissingerAkahira-Sunose(KAS),Flynn-Wall-Ozawa(FWO)and Starink models are 183.97,181.08 and 207.42 kJ/mol,respectively.The proposed MPG model well predicted the mass changes of multi-stage products.The solid-phase char includes multiple components inorganics,primary char,secondary char,pyrochar,etc.The gas yield increases with increasing temperature,with a trend of fast then flat then steep rise.The pyrolysis liquid yield as a whole shows a trend of increasing then decreasing.(2)The development of high-valued carbon sequestration technology.Focusing on the high-value goal of waste cabbage leaves derived biochar carbon sequestration,the physicochemical properties of biochar were analyzed by using characterization methods to investigate the relationship between pyrolysis gases and biochar properties.Besides,the paper proposed the the carbon sequestration balance model(CAATP)to calculate carbon sequestration and emission reduction potential of biochar.The results are as follows:1)the energy recovery from biomass need to focus on process conditions.In terms of biochar properties,pyrolysis gases are correlated with the changes in surface functional groups and microscopic carbon structure of biochar.The abundance of surface functional groups biochar is higher in low-temperature,the abundance of oxygen-containing functional groups could reach 55%,and the structure of high-temperature biochar is more orderly.2)Besides,biochar brings carbon emission reduction benefits by promoting renewable energy cycle,increasing the carbon sequestration potential of biochar and reducing the content of CO2 and CH4 in pyrolysis gases.The carbon sequestration and emission reduction capacity of waste cabbage leaves derived biochar was approximately 990-1230 kg/t.(3)The development of high-valued technologies for multi-technology collaborative negative carbon energy.To fully recover high-value products from waste cabbage leaves,a Multi-stage strategy model based on temperature gradient was successfully proposed.Extracts containing fatty acids were available by alcoholic thermal reaction at 70℃.Pyrolysis oil and activated carbon were obtained by medium temperature pyrolysis and characterized by Fourier transform infrared(FTIR),thermogravimetry(TG),chromatography mass spectrometry(GC/MS)and so on.The results show that the proposed Multi-stage strategy allows full recovery of organic waste.For the application of botanical pesticides,the phenol-rich pyrolysis solution with 50%phenol content could be obtained.In terms of biochar,solid-phase char with BET surface area up to 891.12 m2/g was obtained,and the yields of biochar,pyrolysis liquid and thermally degassed were 43.86%,17.47%and 38.67%,respectively,with process energy efficiency exceeding 42.7%.Conclusively,based on multi-path pyrolysis theory,this paper successfully studied the high-valued utilization path of biochar carbon sequestration and multi-technology collaborative negative carbon energy technology.And,the paper proposes MPG model,CAATP model and Multi-stage strategy model,coupled with analysis of model parameters and results,which provides a novel way and method for comprehensive utilization of waste biomass resources.