CO2 Methanation Reaction: Insights into the Development of Catalysts and Mechanism

Abstract

Considering the global objective to mitigate climate change, many efforts have been put in developing ways and methods to decrease the global effect of CO2. Due to the well-known environmental impact of CO2 emissions, (e.g., increase of the planet’s temperature, rise of the sea level and melting of glaciers), which are accounting for about 79% of total greenhouse gas emissions, development of CO2 capture and utilization (CCU) technologies is a necessity. Along these lines, the catalytic hydrogenation of CO2 using renewable energy has been proposed as a promising process for utilizing CO2, since it enables the reuse of CO2 as feedstock to produce valuable chemicals and fuels, such as methane (CH4). In this thesis, a variety of affordable Ni-based heterogonous catalysts were developed, following different approaches, for the CO2 conversion to CH4 through the well-known Sabatier reaction (CO2 + 4H2 ⇌ CH4 + 2H2O, ΔH298K = –165 kJ/mol). The physicochemical properties of developed materials were evaluated using state-of-art spectroscopy and microscopy techniques, such as high-resolution transmission electron microscopy (HRTEM), steady state isotopic transient kinetic analysis and in-situ diffuse reflectance infrared Fourier transform spectroscopy (SSITKA-DRIFTS), X-ray photoelectron spectroscopy (XPS), and Synchrotron X-ray Absorption Spectroscopy (XAS), etc. In this PhD thesis, a comprehensive literature review presents the most recent advances and developments in the field. Followed by four chapters of detailed experimental methodology and results. The work reported within this thesis demonstrates the unique characteristics of the developed catalysts and the established structure-catalytic performance correlation. Among the different methodologies of promotion (Ni, support) the highest CO2 conversion (77%) was obtained by a Ru-promoted Ni-based perovskite dispersed over alumina with a CH4 selectivity of 96%.

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