Study On The Pyrolysis And The Interaction Of Biomass Based On Its Chemical Group Compositions

In recent years,biomass pyrolysis has become a research hotspot in the field of pyrolysis.As a solid organic matter,the composition of biomass is complex,and the chemical composition of biomass has a significant impact on its pyrolysis behavior.Traditional woody biomass research generally divides its composition into three major categories of cellulose,hemicellulose,and lignin,but this classification does not have universal applicability.In some herbaceous biomass,agricultural waste and marine biomass,in addition to the above three components,there is a certain amount of other components.In order to solve the above problems,our group draws on the concept of"groups"in the field of petroleum research,the biomass composition is divided into six gropus according to chemical similarity,namely oil group,protein group,starch group,lignin group,hemicellulose group and cellulose group.Based on the above classification scheme,this study first established a separation method for the six group-components of biomass,and then investigated the pyrolysis behavior of biomass chemical components and real biomass.Finally,the interaction of each chemical group component in the real biomass pyrolysis process was investigated.It was also investigated whether the pyrolysis behavior of real biomass could be predicted based on its chemical composition.In the first part of this paper,a mixture of several biomass was firstly selected as a raw material for experiment,and a separation scheme of six group-components of biomass was established.The results of FTIR analysis showed that the separation scheme was basically feasible.Then the chemical group composition of seven biomasses was separated by this scheme,and the content of chemical group in each biomass was calculated.In the part of biomass group-components pyrolysis,six model compounds of biomass chemical group-components were selected as raw materials.The pyrolysis experiments were carried out by TG-FTIR.The results showed that there were large differences in thermal stability and pyrolysis behavior of different chemical group-components.The patterns of gaseous products release for different chemical group-components were also different.The kinetic analysis results showed that the apparent activation energy of the oil group was the highest,and it of the hemicellulose group is the lowest.There was no obvious regularity in the effect of heating rate on the apparent activation energy of pyrolysis of biomass chemical group-components.In the part of real biomass pyrolysis,seven real biomasses were selected as experimental materials.The experiments were carried out by TG-FTIR and Py-GC/MS.The results showed that the chemical composition of biomass had a significant influence on its pyrolysis behavior,and different biomasses followed different pyrolysis mechanisms.The apparent activation energy of seven biomasses at 50°C/min was calculated by model-fitting method.The apparent activation energy of jerusalem artichoke stalk pyrolysis was the highest,while it of bamboo was the lowest.The jerusalem artichoke stalk was selected as the representative of real biomass to investigate the effect of heating rate on its pyrolysis process.The results showed that the apparent activation energy at low heating rate was lower than the apparent activation at high heating rate when the conversion rate is less than 0.7,but when the conversion rate was greater than 0.7,the conclusion is reversed.The results of Py-GC/MS experiments showed that the heating rate did not affect the type of pyrolysis products,but affected their relative content.In the final phase of the study,the interaction of each chemical group-components in the real biomass pyrolysis process was analyzed.The heating rates of 50~oC/min and 500~oC/min,the temperature range of 450-600~oC and the step length of 10~oC were selected for calculated the intercropping coefficient of each chemical group-components during pyrolysis.The results showed that the interaction between different chemical group-components was obvious.In the later stage of pyrolysis,the yield of coke could be predicted successfully based on the content of chemical group-components and pyrolysis interaction coefficient.