1. Taiyuan University of Science and Technology (Jincheng Campus), Jincheng 048011, China
2. Shanxi Key Laboratory of Geological for Coal and Coal Measure Gases, Taiyuan 030001, China
3. School of Resources and Geosciences, China University of Mining and Technology, Xuzhou 221008, China
4. Institute of Resources & Environment, Henan Polytechnic University, Jiaozuo 454000, China
Abstract：In order to elucidate the relationship between structure evolution and carbon isotope of alkane gas in coal pyrolysis process, we selected low rank coal to carry out pyrolysis experiments in autoclave closed system. The carbon isotopic composition of alkane gas was analyzed, and the evolution of coal structure was studied using Fourier transform infrared spectroscopy (FTIR). The relationship model between carbon isotope composition of alkane gas and structure evolution was established. Moreover, the reasons for changes in carbon isotope of alkane gas were revealed. The results showed that light carbon isotopes fractionation of lipid chains cause heavy carbon isotopes to be retained in long chains when Ro, max＜1.3%. The materials within the loop, containing heavy carbon isotopes, are not fractionated out heavily when 1.3%＜Ro, max＜2.0%, and carbon isotope of alkane gas still depends on the further fractionation from lipid chains. Namely, the changes in carbon isotope of alkane gas are mainly caused by lipid chain orientation fracture when Ro, max＜2.0%. Since then (Ro, max＞2.0%), due to the intensification of aromatic condensation and disintegration, the heavy carbon in the loop can be released into the alkane gas, and its carbon isotopic composition rapidly becomes heavier. There is a synchronization phenomenon between carbon isotope composition of methane and ethane and structure evolution of lipid chain, and the values of δ13CCH4 and δ13CC2H6 can be used as the sensitivity index of structure evolution of lipid chain. In addition, it was pointed out that Ro, max=1.3% and 2.0% are important nodes in the relationship between structure evolution of coal and carbon isotopic composition of alkane gas in pyrolysis process. The research results have theoretical significance in exploring the coupling relationship between hydrocarbon generation of coal and structure evolution and mechanism of secondary hydrocarbon generation.
简 阔，刘顺喜，陈义林，傅雪海. 低阶煤热解结构演化及与烷烃气碳同位素相关性的红外光谱[J]. 光谱学与光谱分析, 2018, 38(07): 2070-2075.
JIAN Kuo，LIU Shun-xi，CHEN Yi-lin，FU Xue-hai. Infrared Spectroscopic Study on the Structure Evolution of Low Rank Coal and Its Correlation with Carbon Isotope of Alkane Gas in Pyrolysis Process. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2018, 38(07): 2070-2075.
