A Molecular Level Interpretation of the Underlying Chemical Phenomenon of Semi‐coke and Coke Formation: A Treatise from Ab Initio Calculations

Abstract

Chemistry of coke formation has been subject to a wide array of experimental investigations since the advent of industrial coal carbonization process. Roles of different additives in inducing chemical modifications have been examined in this regard. However, similar computational quantum chemistry calculations attempting to obtain fundamental insights into the plausible molecular mechanism operating during the resolidification steps of semi‐coke and coke formation are elusive. Thus, a rational molecular level understanding pertaining to the evolution of chemical structure during coke formation has not developed likewise. In this context, density functional theory calculations have been employed in the present work to comprehend the plausible molecular mechanism of elementary steps driving the semi‐coke and coke formation. Influence of an additional organic H‐donor species on the mechanism has also been explored to ascertain its participation in coke making. Mechanistic steps involved in semi‐coke formation are found to be crucial in determining the final coke structure. Experimental observations relating to the liberation of H• and also molecular hydrogen (H2) during the generation of semi‐coke structure are well corroborated with our investigated mechanistic features. Overall, the work is believed to offer a molecular level interpretation of a much‐exploited chemical phenomenon.