Effect Of 915MHZ Microwave Radiation On The Chemical Structure Of Shanxi High Sulfur Coking Coal

Coking coal is an important industrial raw material,and China's coke output ranks first in the world.Understanding the molecular structure of coal is an important part of coal chemistry research.No widely known molecular structure model of coke.Microwave heating is different from traditional heating methods and has good application prospects in the field of clean coal utilization.However,limited by the research and development of microwave equipment,the study on the influence of915MHz frequency microwave radiation on coal chemical and physical properties is still rare.This paper takes Shanxi high-sulfur coking coal as the object of investigation,analyzes the basic structural parameters of coking coal,and builds a coking coal macromolecular structural unit model.The 915MHz microwave experiment platform was used to conduct radiation tests on coking coal,and samples of different depths and semi-coking coal were collected to characterize the influence and mechanism of microwave on the chemical and pore structure of coal.It is of great significance to optimize the microwave heating process and improve the efficiency and stability of coal microwave desulfurization and dehydration.After microwave radiation,the carbon,nitrogen,and sulfur structures in coal are oxidized,resulting in an increase in the carboxyl content of coal.The layer spacing d₀₀₂,002 peak aromaticity f_a-XRD and I_D1/I_G for judging the graphitization degree increase,and the carbon crystallite diameter L_a and stack height L_c decrease.Among them,the decrease rate of L_a is 0.93%,1.45%,1.76%,6.45%and 1.04%,1.38%,1.88%,6.51%,respectively.The nitrogen structure content of pyridine and pyrrole gradually decreased,and the content of protonated pyridine and nitrogen oxides increased.The nitrogen structure of pyridine and pyrrole is oxidized,causing the content of NO to increase.The content of protonated pyridine and nitrogen oxides in semi-coking coal are increased by 4.08%and 18.44%compared with raw coal,respectively.The content of self-associated hydrogen bonds of hydroxyl groups,ether oxygen bonds and hydroxyl groups in coal increases,which promotes the formation of polymers.The aromatic carbon ratio and aromatic hydrogen ratio of different radiation depths and semi-coking coal samples increased.The aromatic structure in semi-coke is dominated by the penta-substituted benzene ring,and other coal samples have transformed from the high-substituted structure of the benzene ring to the low-substituted structure.Microwave radiation can break the chemical bonds of organic sulfur molecules and produce new sulfur-containing products,including inorganic sulfur and thiophene.A semi-coking coal macromolecular structural unit model with the molecular formula C₁₅₂H₁₁₂N₂O₈S₂ was constructed.The content of acidic oxygen-containing groups(such as phenolic hydroxyl and carboxyl groups)in coking coal decreases with the increase of microwave power and radiation time.During this process,the change law of the specific surface area and pore volume of coking coal presents a trend of"decrease-increase-decrease"and the average pore diameter gradually decreases.Figure 49 table 35 reference 94...