Solubilization of Neyveli lignite by oxidative degradation: A potential source of carbochemicals

The recent and possible future shortages of petroleum-derived hydrocarbons for use as starting materials for the synthesis of organic chemicals/products have stimulated renewed interest in the use of coal as raw material for chemical production. Oxidatively solubilized coal and or lignite (OSC) in alcohol is a potential substitute for value added carbo-chemicals of the future. Phenomenal increase in the solubility of lignite in organic solvent consequent on treatment with dilute nitric acid under mild conditions was considered to be an expedient pathway for its direct utilization. The primary requirements for the solubilization are generation of functional groups like free carboxyl groups and size degradation. For the desired product the reaction should also be guided in such a manner, so that the aromatic/hydroaromatic moieties of the coal/lignite are preserved. The present study aims at the selection of the required reaction parameters for the conversion of lignite to such a product. Characterization of the original lignite and the products have been done chemically and spectroscopically. FT-IR, ¹³C (solid state) and ¹H NMR spectra have shown that substances posses both aromatic and aliphatic characteristics. The dominant functional groups which contribute to the reactivity of the substances are phenolic and carboxylic acids.