Liquefaction of Low-Rank Coals with Hydriodic Acid and Microwaves

Abstract

A novel method for the chemical liquefaction of low-rank coals in relatively moderate conditions and short reaction times is presented. Using concentrated hydriodic acid as the reaction medium, microwaves as the energy source, and reaction times of 20 min at 230°C, up to 50% of the organic carbon of coal can be extracted with THF. The study of the process shows that temperature of the reaction and time are the main factors affecting the desulfurization process. The redox potential and the nucleophilicity of the concentrated hydriodic acid were the driving force of the reaction as experiments with other acids or lower acid concentrations gave worse results.

Microwave pyrolysis of sewage sludge: analysis of the gas fraction

“…Thus, processes such as the drying and heating of minerals and inorganic products, the carbothermic reduction of metal oxides, mineral leaching, coal liquefaction, the production of active carbon, spent carbon regeneration and the surface chemistry modification of carbons are only a few examples of the different processes currently being used or investigated [8][9][10][11][12][13][14][15][16]. Microwave heating has also been considered as an alternative for carrying out the pyrolysis of biomass [17,18], coal [19,20], oil shales [21,22], and various organic wastes [23,24].…”

Part 1. The Effect of Microwave Receptors on the Liquefaction of Turkish Coals by Microwave Energy in a Hydrogen Donor Solvent

“…Application of microwave energy to drying, gasification, desulfurization, pyrolysis, and grindability of coals has been reported. [4][5][6][7][8][9] Monsef-Mirzai et al used microwave energy to energize such reactions as the desulfurization, gasification, and pyrolysis of coals. 8 Reactions were carried out at short time according to thermal processes.…”

“…There are several studies in the literature on the liquefaction of coals using microwave energy. [9][10][11] The microwave absorption capacity of matter depends on its dielectric constant. Coals have a low dielectric constant changing between 4.7 and 5.3.…”

Combination of Microwave and Ultrasonic Irradiations as a Pretreatment Method to Produce Ultraclean Coal

“…Extensive research has been conducted on the use of microwave heating in coal sciences, including the drying, gasification, desulfurization, pyrolysis, and grindability [32][33][34][35][36][37][38][39]. Microwave is a nonionizing electromagnetic radiation with frequencies in the range of 300 MHz to 300 GHz.…”