十八烷的裂解动力学研究(I):气态烃组分及其碳同位素演化特征

Pyrolysis Kinetics of Pure n-C_18H_38 (I): Gaseous Hydrocarbon and Carbon Isotope Evolution

本文通过对纯烃类化合物——正十八烷的动力学模拟实验,阐述了正十八烷裂解过程中气态烃组分及其同位素的演化特征,获得了产自正十八烷的甲烷生成动力学参数。运用动力学参数将模拟实验结果外推到地质条件下,表明由烷烃裂解形成的甲烷主要生成于150～200℃(Easy%Ro介于1.0%～2.0%)的范围,裂解产生的甲烷、乙烷、丙烷的碳同位素分馏效应与Easy%Ro的关系曲线受升温速率的影响,不能直接应用于地质条件。

The purpose of this study is to reveal the composition and carbon isotopic variation of gaseous hydrocarbon including methane, ethane and propane by combining the kinetic simulating experiment of pure n-C18H38 and the GC-IRMS analysis of methane, ethane and propane in the pyrolysates. The results of this experiment can be used in natural conditions by applying the kinetic parameters of methane. Extrapolation of these kinetic parameters to geological heating rates suggests that methane thermally cracks from alkane generates in condition of 150℃〈t〈200℃ （1. 0%〈Easy%Ro〈2. 0%） and the relationship between δ^13C1～3 and Easy%Ro is affected by the heating rate.