Biomass residues purification: elimination of oxygen from oxolane and its monomethylated derivatives through hydrodeoxygenation process

Abstract

The persistent global demand of fossil fuels has spurred significant interest in the invention of new renewable energy sources to replace finite, non-renewable fossil fuels. Among these sustainable energy options, biomass stands out as a promising candidate as environment friendly alternative fuel. However, the organic compounds found in biomass contain a high oxygen content, leading to several undesirable characteristics in biofuels, including low energy density, less stability, high viscosity, and corrosion. Consequently, researchers have devised various upgrading techniques, with a particular emphasis on the hydrodeoxygenation (HDO) process, to enhance the quality of biofuel. In this report, we investigated the treatment of Oxolane, 2-Methyloxolane and 3-Methyloxolane via adsorption and catalytic hydrogenolysis (HDL) processes. These processes aim to remove the oxygen heteroatom from these compounds, ultimately achieving the desired purity levels. To elucidate the underlying mechanisms, we employed the B3LYP/6–31G(d) and LanL2DZ/6–31G(d) methods of DFT for reaction without or with catalysts. The hydrogenolysis, in the presence and absence of a catalyst is carried at a temperature and pressure of 523 K and 40 bar, respectively. We meticulously analyzed the variations in geometries, thermodynamic and kinetic properties to gain insights into the whole processes. For each molecule, the sequence involves ring opening of C–O bond, followed by the elimination of a water molecule. The first hydrogenolysis step yields an alcohol as a reaction intermediate, while the second hydrogenolysis step results in the formation of an alkane. Geometric parameters showed the increased reactivity of Oxolane and its derivatives in the presence of tungsten disulphide (WS2) catalyst. Chemical potential indicates the charge transfer occurred in all, and the highest charge transfer is observed in Oxolane in the presence of tungsten disulphide (WS2) catalyst.