Mechanism of the Alcohol-Mediated Alkylation of Solid Fossil Fuels at the Low Stage of Coalification
S. I. ZHEREBTSOV1, N. V. MALYSHENKO1, Z. R. ISMAGILOV1,2
1Institute of Coal Chemistry and Material Science, Siberian Branch of the Russian Academy of Sciences, Sovetskiy Pr.18, Kemerovo 650000 (Russia)
2Kuzbass State Technical University, Ul. D. Bednogo 4, Kemerovo 650000 (Russia)
Keywords: brown coal, alkylation with alcohols, bitumoids, mechanism, esterification, interesterification
Abstract
Experiments on low-temperature alkylation of solid fossil fuels (SFF) of low coalification stage - brown coal, peat - were carried out using alcohols as alkylating agents. On the basis of the results of experiments involving analytical methods (IR, NMR spectroscopy, and gas chromatography-mass spectrometry) and the experiments with methanol labelled with 14С isotope, the distribution of the attached carbon from alcohol in soluble and insoluble products of brown coal alkylation was established. The efficiency of alkylation of brown coal and peat by alcohols under catalysis with proton acids is directly proportional to acid strength and increases in the sequence of alcohols: methanol < isopropanol < n-butanol < isobutanol < n-amyl alcohol. It was shown that esterification and interesterification of carboxylic and ester groups of the organic mass of SFF at low coalification stage in the presence of strong protonic acids proceed via AAC2 and AAL1 mechanisms (according to Ingold).
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