Research On Gas Chemical Generating Mechanism In The Process Of Coal And Gas Outburst

In order to study the source of excess gas in the process of coal and gas outburst and reveal the path and mechanism of gas generation in the process of coal and gas outburst,a combination of experimental research,molecular modeling and theoretical analysis was used to test and obtain the basic information of five types of coal molecular structures,build coal molecular structure models in 5 mining areas,analyze the static physical properties of coal molecular structure,determine the chemical reaction path of gas generation,and explain the special phenomenon of excessive gas.Through elemental analysis experiments,the percentage content and atomic ratio of C,H,O,N,and S in the molecular structure of coal were obtained.According to the one-to-one correspondence between the peaks of the infrared spectrum and the functional groups,the types of functional groups in the molecular structure of coal were qualitatively analyzed.According to the 13C-NMR peak fitting area,12 basic parameters of coal molecular structure were quantitatively calculated.The aromatic structure and aliphatic carbon structure information in coal molecules were calculated,and the existence of oxygen-containing functional groups and N and S forms were analyzed.The initial structure model of coal was constructed with the help of Materials Studio software,and the lowest energy conformation was obtained after geometry and energy optimization.The 13C-NMR of the calculated model was compared with the experimental spectrum,and the model was constantly revised.Based on quantum mechanics and DFT,the Dmol3 and Castep module were used to calculate and analyze the static physical properties of coal molecular structure.In the molecular structure of coal,the s and p orbital electrons of O,N,S were prone to electronic transitions,resulting in new chemical bonds.Oxygen-containing functional groups had high electron density and were prone to breakage of chemical bonds.Oxygen-containing functional groups,methyl carbon and ethyl carbon in aliphatic side chains were active sites.There are HOMO and LUMO inside the molecular structure of coal,which were prone to electron transfer.The C-N bond length was short,the bond level is high and the stability was the highest.The phenolic hydroxyl group was stabler than the etheroxy group.The C-S bond was long and the bond level was low,which is most prone to breakage.The bridged C-C and the C-C in the ethyl carbon were easily broken.C-C was more active than C=C,-CH3 had strong electronegativity,and was prone to hydrogen abstraction reaction.Pyrrole was more active than pyridine,and the oxygen charge was all negative.Dmol3 was used to calculate the transition state of small molecular organic compounds in chemical reactions.The H atom had a tendency to bond with the side chain of the benzene ring.According to the value of the bond dissociation energy,the breaking order of the functional groups in the molecular structure of coal was determined:ether oxygen?carbonyl?hydroxy?methyl of aromatic side chain?methine?methyl directly connected to benzene ring?aromatic hydrocarbon.The chemical reaction path of gas generation was proposed,and the mechanism of gas generation in the process of coal and gas outburst was revealed.This dissertation enriches the theoretical research on excess gas and has important significance for understanding the source of excess gas in the process of coal and gas outburst.There are 74 figures,48 tables,and 228 references in this dissertation.