Exploring the Potential of Coal: Electrolysis and Extraction for Chemical Recovery, Oral Presentation
Authors: Donneys Victoria Dayana , Haque Alamgir Mojibul , Miah Md Sumon , Riyad Mahmudul Hassan , Saha Dipu , Abbasi Ehsan , Botte Gerardine G 
Published: December 2024

Formed from the fossilized remains of ancient plants, coal is a combustible sedimentary rock classified as a nonrenewable resource due to its extremely slow formation process. The chemical structure of coal contains diverse types of carbon, including aliphatic carbons, aromatic carbons, and carbonyl carbons [1], [2]. Coal is considered the most economical source of energy; however, its potential as a repository for valuable chemical compounds remains underutilized. Although solvent extraction offers a way to extract specific components from coal, it comes with limited extraction efficiencies and significant environmental, and economic drawbacks.

Coal electrolysis is a process that utilizes electricity to break down and oxidize carbon structures in diverse ways, yielding liquid-phase products [3]. One key application of coal electrolysis is the production of hydrogen gas. Traditional methods, such as Indirect coal liquefaction (ICL) and Direct coal liquefaction (DCL), rely on high-temperature and high Pressure (ranging from 200-1450°C, 100-200 atm) respectively. In contrast, the technology known as the “Continuous Coal Electrolytic Cell (CEC)” facilitates the direct conversion of coal into valuable chemicals and liquid fuels at mild temperatures (25-180°C) and low pressures (1-2 atm) [4]. Therefore, this process could potentially be more efficient and less energy-intensive than conventional methods. In the CEC, electric power is applied to a coal-slurry to directly convert the coal into pure clean hydrogen, and organic compounds (liquid form), with minimum CO2 emissions. During the CEC process, the surface of the coal particles (electrolyzed coal char) gets oxidized into lower molecular weight hydrocarbons than coal. Subsequently the electrolyzed coal char undergoes extraction to separate the liquid fuels and/or valuable chemicals. This technology has already proven that temperature and applied current are the most influential factors in maximizing hydrogen production. However, the conditions for obtaining various liquid-phase products have not yet been optimized.

In this study, the effect of coal particle size during electrolysis and the subsequent extraction process was explored more in-depth specifically to determine the characteristic of the liquid extracted. Three coal particle size were electrolyzed using Pt-Ir catalyst, followed by extraction using two different solvents. The changes in the main functional groups of coal particles were studied by FTIR, while proximate analysis and carbon structure were analyzed by TGA/DSC and CHNS, SEM and XRD, respectively. Our findings reveal the distribution of sulfur and nitrogen after electrolysis and the benefits of solvent selection since it is known that the solvent influences the interaction between organic and mineral matter. By demonstrating that coal electrolysis, combined with extraction, can remove valuable chemicals, new market opportunities emerge for coal across various applications.

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