Evolutive Characteristics of Carbazole Compounds in Nonhydrocarbon of Coal and Mudstone at Different Temperatures

Key words: 
• coal /
• mudstone /
• NSO /
• carbazole compounds /
• maturity /
• isomerization

Abstract: Through thermal simulation experiments of coal and mudstone in low mature stage(Ro=0.5%) from different sedimentary environment in one area at different temperatures（200℃,250℃,275℃,300℃,325℃,350℃,400℃,450℃）added with water in the closed system and separation and GC/MS quantitative analysis and identification of carbazole compounds in sample extracts at different temperatures, this paper discussed the distribution of carbazole compounds in this two kinds of samples at different simulation temperatures.The separation adopt twostep Column Chromatography. And absolute quantification uses Nphenylcarbazole added in neutral nitrogencontaining compounds as an internal standard . Based on simulation experiment, the article analyzes the evolutive characteristics of experimental productscarbazole compounds in nonhydrocarbon and discusses the evolution mechanism of them at different temperatures. The experimental results show that in the coal and mudstone samples the total contents of carbazole compounds and the contents of carbazoles, methyl carbazoles, dimethyl arbazoles, benzocarbazoles increase with thermal evolution temperature increasing and reach thire maximum during 325~350℃ and show downtrend after 350℃. From these changes, we can see that the formation of the compounds have certain relationship with hydrocarbon generation of rock samples.The changes with temperature of the contents of carbazole compounds depend on release and fission rate of them. The results from experimental data analysis show that contents increase when release rate is more than fission rate and contents decrease contrarily. In fact，the changes with temperature of the contents of carbazole compounds is similar to that of liquid hydrocarbons. According to the thermal simulation experiments, organic matter begin to produce hydrocarbon during 300~350℃ and reach thire maximum at about 350℃ in general. It is pointed out that nitrogencontaining compounds in geological body are the products of rockforming diagenesis of sedimentary organic matter rather than directly inherited from organism. GC/MS date of carbazole compounds indicate that the relative content of methyl carbazoles isomers changes drastically with experimental temperature.
In this two kinds of rock samples of high temperature experiments，the relative content of four methyl carbazole isomers(1 methyl carbazoles,2 methyl carbazoles,3 methyl carbazoles,4 methyl carbazoles) of methyl carbazoles present some of regular changes with temperature increasing. The content of 1methyl carbazole always predominate compared with that of the other three isomers, but the relative content of them changes drastically with temperature increasing. At 200℃, the content distribution of 2 methyl carbazoles,3 methyl carbazoles and 4 methyl carbazoles show an asymmetric “V”with forerake which become retroverted with the temperature reaching 350℃ . The relative content of dimethyl carbazoles, exposed type such as 2,6(+2,7) dimethyl carbazoles and 3,5 dimethyl carbazoles,and shielded type and half shielded type such as 1,8dimethyl carbazoles, 1,4dimethyl carbazoles and 1,5 dimethyl carbazoles, come to a head during 325～350℃and show downtrend after 350℃。In benzocarbazoles, benzo(a)carbazoles and benzo(c)carbazoles are the predominent types, benzo(b)carbazoles are few. With temperature increasing,the relative content of benzo(a)carbazoles, benzo(b)carbazoles and benzo(c)carbazoles changes drastically, reach their highest values during 325~350℃ and bagin to decrease after 350℃. It can be seen from benzocarbazole ratios(benzo(a)carbazole/(benzo(a)carbazole+benzo(c)carbazole)) that change of the ratios with temperature have good correlation with hydrocarbon generation of rock samples.But all the ratios are in the norrow range of 0.45~0.54.