Evolution Kinetics And Mechanisms Of Methane And Hydrogen From Low Rank Coal And Different Chemical Components

Gaseous and liquid hydrocarbon could be formed during thermal evolution of the origanic matters in the low rank coal, their formation process and mechanisms are main topic for coal chemistry and the coal geochemistry.Because of methane and hydrogen are the main reactions duing the coal pyrolysis, analysis of their formation and reactions characteristics may help in understanding the pyrolysis mechanisms.In addition, the theoretical foundation can be provided for the explanation of the generation mechanisms about the coal-bed gas and production of the clean evergy. In this paper, the humic acids were obtained from the five coals in Wulatuga and Wunite coalmine, Erlian Basin, and the pyridine was used to extract the residuals after humic acid was removed. TG/MS and FTIR were used to study the formation process and mechanisms of the methane and hydrogen during the pyrolysis of the origin coals(YM), the humic acids(HA), the residuals after humic acid was removed(HACM), the residuals extracted by pyridine and the asphalt. Main conclusions are drawn as follows:1.The structure characteristic:the fa of YM is reduced with the increase of H/C, and the Hal/Har in HA is larger than YM, the aliphatic chain is also longer than YM. After the humic acids were removed, 2920 cm-1,1620 cm-1and 2860 cm-1 become weaker and the oxygen-containing functional group reduced, but the extraction .has no effection on fa.2.The DTGmax of YM is larger with the 2924cm-1, at the high temperature stage , pyrolysis curve of HA,HACM and CTCM appear'bimodal peaks'phenomena., the asphaltine has the maximum weight loss .3.Methane is evoluted from 100℃to 800℃, the total methane of YM is positive related with H/C, and the formation of methane in HA is related to the methyl. The evolution curves of CH4 of HACM and CTCM apear trimadal peaks, the total methane yields from asphaltine has the minumin value, and HA is maximum.The initial generation temperature of H2 is about at 300℃, the evolution of hydrogen in YM is derived from the aliphatic C=O in the aliphatic structure.The Tmax of H2 generation fron HA increases with the increatment of 2964/1618 cm-1. For HACM and CTCM, their tolal hydrogen yields are similar., the initial temperarure of H2 from asphaltine is higher than HACM and CTCM.4.The evolution curves of CH4 and H2 showed that they were not the results of only one reaction. TakingⅣfor example, the H/C and O/C are relating to the total methan and hydrogen during the pyrolysis of YM, HACM and CTCM. The methan yield were higher after extraction with alkali solution and pyridine, and the extraction with Pyridine rrduced the yield of H2.