Separation and characterization of squalene and carotenoids derived sulfides in a low mature crude oil

Jianxun Wu^a, Weilai Zhang^a, Chao Ma^a, Limin Ren^a, Sumei Li^b, Yahe Zhang^a, Quan Shi^a,⁎

^a State Key Laboratory of Heavy Oil Processing, Petroleum Molecular Engineering Center (PMEC), China University of Petroleum, Beijing 102249, China 

^b State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China

^*Corresponding Author: E-mail address:sq@cup.edu.cn(Q. Shi)

DOI:10.1016/j.fuel.2020.117536

Keywords: Sulfur Compounds; Sulfides; Squalene; Carotenoid; FT-ICR MS

Abstract: An unusual distribution on molecular composition of organic sulfur compounds (OSCs) was found in a crude oil from the Bohai Bay Basin (China) that contains negligible thiophenic sulfur compounds but abundant in C30 and C40 sulfides. The sulfides were separated from the crude oil by methylation/demethylation method and char acterized by gas chromatography-mass spectrometry (GC–MS) and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). A novel series of C30 OSCs that possess a bio-precursor of squalene were identified. The lexene (C33) derived OSC was also identified for the first time in the crude oil, which indicates a strictly anaerobic condition during the early diagenesis of the source rock. Most C40 sulfur compounds were verified to be sulfides having a β-carotane skeleton. Most identified sulfides possess a thiolane group with a quaternary carbon atom or a thiane group within their carbon skeletons.