Characterization of kerogen from Messel shale based on multistage alkaline permanganate degradation

Abstract

A 17-step alkaline permanganate degradation of kerogen from Messel shale (F.R.G.) was carried out. A very high total yield of oxidation products was obtained (91.7 % based on original kerogen). Detailed g.c.m.s. analyses of ether-soluble acids, soluble products of further controlled permanganate degradation of precipitated acids and acids from aqueous solutions, served as a basis for the quantitative estimation of the participation of various types of products and for comparison with other kerogens. Taking into account the slight aliphatic nature of the acidic oxidation products (53.4 %), the existence of an aliphatic cross-linked nucleus in the Messel shale kerogen is postulated. However, on the basis of high participation of both aromatic (21.2 %), and alkane-polycarboxylic (20.2 %) and cycloalkanoic (5.2 %) acids, a high proportion of alicyclic, heterocyclic and aromatic structural elements in the structure of this kerogen was demonstrated. The most interesting finding was the isolation and identification, in significant amounts, of a series of monocarboxylic mono- and bicyclic cycloalkanoic acids. A small quantity of isoprenoid acids was found in the oxidation products. A homogeneous structure of the Messel shale kerogen is suggested.