Effect of functional characteristics of Yanchang coal micro-components on low-temperature pyrolysis reactivity

The vitrinite enriched coal samples (YCV) and inertinite enriched coal samples (YCI) obtained from mac⁃ eral separation of a low metamorphic bituminous coal were studied in this paper.Combined with thermogravimetric， full⁃two⁃dimensional gas chromatography⁃mass spectrometry (GC×GC-MS)，FT-IR and Raman analyses，the effects of different maceral functional groups and carbon structures on the composition characteristics of the pyrolysis products at low temperature were investigated.The analysis of coal structure found that the relative content of amorphous carbon in YCV is relatively high，the side chains connected are more and it is rich in phenol —OH，alcohol C—O，phenol C—O，methyl and methylene and other types of functional groups.However，YCI has higher graphitization degree and condensation degree，and has more stable aromatic structure，in which aromatic C=C，aromatic C=O and R—C=O are more. The oxygen⁃containing functional groups are mainly carboxyl， carbonyl and aromatic ether. Low⁃temperature pyrolysis experiments show that compared with raw coal and YCI，YCV tar yield，pyrolysis water and pyrolysis gas yield are the highest，and semi⁃coke yield is the lowest.Pyrolysis gas composition analysis and tar compo⁃ sition analysis found that the relative content of H2 and CH4 in YCV pyrolysis gas is higher，and the content of aliphat⁃ ic hydrocarbon compounds and phenolic compounds in tar is higher. This is due to the relative content of fatty side chains in YCV is relatively high and unstable. The temperature required for the thermal decomposition of the side chain is relatively low，which facilitates the generation of low⁃molecular free radical fragments and combines with H free radicals to form small molecules of H2，CH4 and releases aliphatic hydrocarbon compounds in tar. The high content of phenolic compounds is closely related to the more phenolic hydroxyl functional groups in the YCV structure.The relative content of CO and CO2 in YCI pyrolysis gas is relatively high，and there are more polycyclic aro⁃ matic hydrocarbons， polycyclic aromatic hydrocarbons and heteroatomic compounds in the tar， which are closely related to the higher graphitization degree of YCI，more stable aromatic rings in the structure，and abundant oxy⁃ gen⁃containing functional groups such as aromatic C=O，R—C=O and carboxyl groups in the structure.