Establishment Of Molecular Model Of Corn Stalk And Study On Kinetics Of Pyrolysis Reaction

In this paper,the overall molecular model of corn stalks and the research on the pyrolysis of each component are carried out.The research content of the project is divided into two parts:theoretical research and experimental research.The relationship between the pyrolysis of each component(cellulose,hemicellulose,lignin)and the relationship between their structural parameters and the overall model of corn stalk,and the reactivity of the molecular structure was evaluated from the perspective of thermodynamics and kinetics.In this way,a method for constructing a biomass structure model is formed.The first aspect of theoretical research is to classify the structural characteristics of biomass monomers,and to combine molecular simulation methods such as quantum chemistry,molecular dynamics,and density functional theory to perform pyrolysis simulation of each component of corn stalk,and study the composition of each component.The bond breaking rule realizes the prediction of the product distribution and then obtains the microchemical evolution law during the pyrolysis process.The second is based on the pyrolysis law of the above components of corn straw,mixing the components in proportion to form a three-dimensional structure model of corn straw.For experimental research,Py-GC/MS was used to perform fast pyrolysis experiments on cellulose to analyze the pyrolysis characteristics of cellulose and the effect of pyrolysis temperature on product distribution.The specific contents of the research process are as follows:Summarize the model compounds of cellulose,hemicellulose,and lignin,and select the most suitable structural unit.For the selected model compounds,the pyrolysis instrument and gas chromatography-mass spectrometry(Py-GC/MS)were used to detect the products that may be produced during the pyrolysis of cellulose.According to the prediction results of pyrolysis products obtained by Py-GC/MS technology,the reaction pathway design of the cellulose model compound cellobiose during the pyrolysis process was simulated using Materials Studio software.Based on the previous research,this paper designed the pyrolysis reaction pathway,and determined the only transition state of each pyrolysis pathway of cellulose,hemicellulose and lignin,according to the transition state search theory.Then the calculation and comparison of reaction energy barriers in different pathways are performed to determine the most optimal pathway for the pyrolysis of each component.Summarizing the previous research on the determination of corn straw components,the three components were combined in proportion to obtain a macromolecular model of corn straw.The molecular structure model of corn straw was revised,optimized and verified by the pyrolysis law of each component.