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Geochemical Journal, Vol. 46 (No. 4), pp. e33-e37, 2012

EXPRESS LETTER

Influence of organic-inorganic interactions on the preservation of sedimentary organic nitrogen: A preliminary experimental study

Kangle Ding,1,2 Yue Luo,1 Jingfu Shan3 and Fujia Guan4

1School of Chemistry and Environmental Engineering, Yangtze University, Jingzhou, Hubei 434023, P.R. China
2Key Laboratory of Tectonics and Petroleum Resources of Ministry of Education, China University of Geosciences, Wuhan 430074, P.R. China
3School of Geosciences, Yangtze University, Jingzhou, Hubei 434023, P.R. China
4Key Laboratory for Drilling and Production Engineering of Hubei Province, Jingzhou, Hubei 434023, P.R. China

(Received February 28, 2012; Accepted June 22, 2012; Online published July 27, 2012)

Abstract: Experiments simulating reactions between pyrrole, hydrogen sulfide (H2S), and aluminum oxide (Al2O3) using a dynamic thermochemical process simulator were conducted to investigate the effect of organic-inorganic interactions on pyrrolic N compounds. The results showed that N-S atomic exchange occurred at 350°C with thiophene as the main product. Thermodynamic studies indicated the reaction of pyrrole with H2S could proceed spontaneously in most geologic settings (0-200°C). Thermochemical conversion of pyrrole into thiophene was found to be catalyzed by Al2O3 but inhibited by an increased volume of water. These findings suggest that conventional models may not fully account for the geochemical processes that result in the abundance and distribution of pyrrolic N compounds in sediments and crude oils. The organic-inorganic interactions in sedimentary basins may also have direct effects on the fate and preservation of pyrrolic N compounds in subsurface reservoirs.
Key words: organic-inorganic interaction, pyrrolic N compound, alteration, N-S atom exchange


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