The Evolvement And Mechanism Of Coal Vitrinite Nanopores In Coalification Process

Based on Huainan and Huaibei coal sample picking native homogeneous structure of coal vitrinite, make pulverized coal X-ray statistical selection homogeneous samples of 90% purity vitrinite, Liquid Nitrogen Adsorption and 13 C NMR and XRD, EPR and FT-IR study different metamorphic degree of coal macromolecular structure evolution regularity and mechanism of nanometer pore. The following main achievements were obtained: Reveals the vitrinite nanopores of deep into the response characteristics of metamorphism and magmatic thermal metamorphism, Coal vitrinite nanopore in 0.7% <Ro,max<1.2% pore volume and surface area decreased, 1.2%<Ro,max <1.9% pore volume and surface area increase,and magmatic thermal metamorphism coal higher than plutonic metamorphism,1.9%<Ro,max<2.2% pore volume and surface area decrease. Reveals the evolution rules of macromolecular structure of coal vitrinite and mechanism, 0.7%<Ro,max<1.2%, coal vitrinite carboxyl and hydroxyl groups in the esterification reaction is more significant,free radical concentration changed little, carboxyl, hydroxyl reduce with coal rank,structure of fat increase along with the coal rank; 1.2%<Ro,max<1.9% stage, fat structure cracking in coal vitrinite, free radical concentration increasing, the change is bigger, fat content structure and methyl rapidly reduced and magmatic thermal metamorphism of coal structure of fat loss rate for deep metamorphism faster; 1.9%<Ro,max< 2.2% stage, the aromatic ring of coal vitrinite polycondensation reaction and fused ring effect significantly, fat structure and methyl content is reduced, and the previous stage, the regularity is more significant. This paper expounds the coal vitrinite nanopores evolution mechanism, along with the process of coalification coal of hydroxyl and carboxyl in 0.7%<Ro,max<1.2% phase combination of produced water in unleashed formation pressure condition, the results in the decrease of entrance,specific surface area; Fat structure of methyl, methylene, methyl in 1.2%<Ro,max<1.9%cracking reducing blowholes, generate methane and magmatic thermal metamorphism of coal structure of fat loss rate for deep metamorphism faster, leading to the entrance of coal, specific surface area increased and magmatic thermal metamorphism of coal entrance, large specific surface area deep metamorphism;1.9%<Ro,max<2.2% stage, the condensation of aromatic ring and thick cyclization, coal macromolecular structure porosity "remove" in the homogenization process.