Production of Benzene Poly(carboxylic acid)s and Small-Molecule Fatty Acids from Lignite by Catalytic Oxidation in NaVO3/H2SO4 Aqueous Solution with Molecular Oxygen

Abstract

Carboxylic acids are widely used in industry and are considered an important type of chemicals. The production of carboxylic acids through oxidation of lignite is very promising. The traditional alkali−oxygen oxidation of lignite can produce high yields of carboxylic acids, but the process consumes a great deal of alkali and acids and the high reaction temperature increases the energy consumption. In the present work, we found that carboxylic acids, including small-molecule fatty acids and benzene poly(carboxylic acid)s, could be obtained by catalytic oxidation of lignite in NaVO3/H2SO4 aqueous solution with molecular O2. The effects of NaVO3/coal mass ratio, H2SO4 content, reaction temperature, initial O2 pressure and reaction time on the conversion of lignite and yield of carboxylic acids were investigated. In the process of reaction, lignite is first converted into water-soluble intermediates, which are then converted into carboxylic acids. The second step is the rate controlling step. It has been foun...