Authors : I.S. Ike, B.C. Udeh, L.E. Aneke and K.B. Oyoh
Abstract: The potential of producing organic carboxylic acids from low-rank coals (lignite) using an oxidizing agent, hydrogen peroxide (H2O2) has been investigated. Five samples of pulverized lignite coal (C = 65.2-74.8% on d.a.f. basis) of different sizes were contacted with 20 volumes of 30% H2O2 at different constant temperatures and residence times to yield organic acids of varying yields and concentrations. The analytical and graphical results indicate that an increase in reaction temperature and residence time and a reduction in particle size increases the yield; selectivity and carbon conversion to the organic carboxylic acid with a maximum at a temperature of 60°C, a residence time of 24 h and a particle size range of 0.1-0.5 mm beyond which they (optimum reaction variables) reduce rapidly. The production at these optimum conditions permits the carbon conversion to water-soluble organics to reach 0.75 with a selectivity of 3.0 in which about 50% were small molecules: methanol, formic acid, acetic acid, glycolic acid and malonic acid with a yield of approximately 9.72 g /20 g of coal as is shown in the study. The high yields, selectivity and conversion to organic carboxylic acids are closely related to the structure of the low rank coals and the strength of the aqueous hydrogen peroxide (H2O2).
I.S. Ike, B.C. Udeh, L.E. Aneke and K.B. Oyoh, 2011. Production of Organic (Carboxylic) Acids from Coals Through Liquid-Phase Oxidation of Coals: New Route for Utilizing Low-Rank Coals. Journal of Engineering and Applied Sciences, 6: 109-113.