Abstract
It has become increasingly important to control carbon dioxide (CO¬2) emissions and at the same time generate fuel sources to meet the growing global energy consumption need. CO2 (dry) reforming of methane (DRM) is a viable process as it generates fuel (syngas) and utilises greenhouse (CH4 and CO2) gas at the same time. The success of this process relies on the development of suitable noble-metal free catalysts. First principle’s based computational methods, such as density functional theory (DFT), has become a powerful predictive tool for catalyst development in modern science. Therefore the main objective of this thesis work has been to investigate suitable catalysts using computational methods for gas–phase CO2 utilisation reactions. In this research work, DFT calculations provided us with the fundamental insights into the DRM mechanism over bimetallic Sn/ Ni (111) periodic model surfaces. This analysis showed that low Sn concentration on Ni surface effectively mitigates carbon formation without compromising the CO2 conversion and the syngas production, showcasing superior characteristics of the bimetallic catalyst towards carbon tolerance stability. Other heterogeneous catalysts such as Ni2P and MoP have also been studied in this thesis. Theoretical analysis of DRM reaction on the unexplored nickel phosphide Ni2P (0001) surface showcased suitable syngas production under DRM reaction temperatures with low carbon deposition formation on the surface. This was mainly attributed to a lower number of active sites available for carbon adsorption compared to oxygen on the Ni2P (0001) surface. DFT study on activation of CO2 and CO on MoP (0001) and Ni2P (0001) surfaces showcased selective CO production from CO2 to be possible on both the surfaces. Further, direct CO activation is favoured on the MoP (0001) surface. Surface bounded oxygen removal on Ni2P (0001) is reasonably favourable. Findings from this thesis work will be beneficial in developing more robust catalysts for gas phase CO2 utilisation reactions and could contribute to a better understanding of CO2 conversion processes, catalysts deactivation and thus helping to develop new families of powerful catalysts for a greener society