(584a) The Structural Characteristics of Oil Shale Kerogens Changed with Their Humic Degree

Qian Wang¹, Qing Liu¹, Fan Yang¹, Yucui Hou², Weize Wu^1,*

¹State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China

²Department of Chemistry, Taiyuan Normal University, Taiyuan 030031, China

Oil shale is an important alternative energy resource, and the structure, especially the structure of kerogen is the foundation of its application. In this work, structural characteristics of Longkou, Huadian and Yilan kerogens with an increasing humic degree were studied. The relationship between structural characteristics and their humic degree were revealed. ¹³C NMR, FTIR, XPS, XRD and the ion-exchange were used to obtain information on carbon skeletal structure, functional groups, the forms of heteroatom, the form of aliphatic carbon and the contents of carboxyl and phenolic hydroxyl groups. It was found that the kerogens are mainly composed of aliphatic structure, dominantly as CH₂ chain. Moreover, the ratio of aliphatic carbon (f_al, aliphaticity) and average methylene chain length (C_n) decrease with increasing humic degree. In these kerogens, most of their aromatic clusters are disorder. Furthermore, the ratio of aromatic carbon (f_a, aromaticity) and average aromatic cluster size increase while the substitutive degree of aromatic ring decreases with increasing humic degree. With increasing humic degree, the content of O=C−O (ester and carboxyl) decreases and that of C−O (alcohol, phenol, and ether) increase. The organic nitrogen in the kerogens exists as pyridinic, amine, pyrrolic and chemisorbed nitrogen oxides. The contents of pyridinic and chemisorbed nitrogen oxides increase while those of amino and pyrrolic decrease with increasing humic degree. In addition, organic sulfur in these kerogens exists as aromatic and aliphatic sulfur, sulfone and sulfoxide. The contents of aromatic sulfur and sulfoxide increase while that of aliphatic sulfur and sulfone decrease with increasing humic degree.

This work was supported by the National Basic Research Program of China (2014CB744301).

Keywords: Structural characteristics; Oil shale kerogen; Humic degree; Relationship