Morphology Engineered Nanocatalysts for Sulfur Gases Hydrogenation

Abstract

This research sets the scene for a fundamental understanding of how different phenolic molecules (e.g., phenol, o-cresol, m-cresol, and p-cresol) found in the bio-oil behave when they come into contact with the catalyst surface (Ni2P) and how their hydrodeoxygenation (HDO) reaction progresses over the Ni2P surface. The hydrodeoxygenation (HDO) process is responsible for removing the oxygen content of pyrolysis oil compounds, particularly through the direct deoxygenation technique. Ni2P, one of the most common transition metal phosphides (TMPs), serves as the candidate surface of this study. Two descriptors were employed for investigation; the optimization of the adsorption configuration of phenolic compounds and the net charge distribution between the surface and adsorbate. According to the adsorption energy studies, the horizontal configuration of the o-cresol molecule on the Ni2P hollow site presented the most optimized configuration with the least negative adsorption energy (-0.26 eV) among the molecules. Furthermore, this aforementioned configuration was the most stable and optimized structure, resulting in the most negative net charge density at -0.286 |e|, as determined by the Bader charge analysis calculations. Consequently, the o-cresol molecule in that configuration was chosen to understand the HDO reaction, which resulted in two exothermic steps out of six, including oxygen carbon (O-C) bond cleavage. This implies the energetically favorable removal of oxygen, ultimately optimizing bio-oil upgrading efficiency and energy production.

Date of Award	Aug 2023
Original language	American English
Supervisor	Kyriaki Polychronopoulou (Supervisor)