Carbon-based Nanomaterials for CO2 Capture and Conversion

Abstract

The rise in industrialization has spurred an unprecedented demand for energy, crucial for economic growth. However, conventional power generation's reliance on fossil fuels significantly contributes to carbon dioxide (CO2) emissions, exacerbating global warming and threatening terrestrial life. Hence, this thesis focuses on Carbon Capture and Storage (CCS) and Carbon Capture and Utilization (CCU) technologies. Chapter 2 provides an overview of methodologies and techniques used to investigate catalyst structure and behavior, including catalyst testing rigs and characterization techniques. In Chapter 3, we successfully synthesized nitrogen-doped mesoporous carbon nanospheres (Mx) using an aqueous synthesis route with urea-phenol-formaldehyde resin and a soft template. These N-MCNs, with nitrogen contents from 0.48% to 1.52% and high surface areas (486.4 to 683.9 m²/g), exhibited uniform pore channels of around 3.2 nm. The CO2 adsorption and desorption performance of Mx were evaluated under various conditions, revealing exceptional CO2 capture capabilities, particularly the M0.1 sample, which achieved 2.53 mmol/g at 10% CO2 by volume. The high performance is attributed to ordered mesopore channels, structural micropores, and nitrogen functionalities, which enhance CO2 adsorption. N-MCNs demonstrated high stability and recyclability, thus reducing costs and complexity. In Chapter 4, novel Ru-doped g-C3N4 catalysts were synthesized to assess their performance in thermocatalytic CO2 hydrogenation. Among catalysts with varying Ru loadings, Ru-1.0 exhibited the highest density of active sites, achieving 36.8% CO2 conversion at 450°C and 83% selectivity for CO at 375°C. Higher Ru loadings resulted in lower CO selectivity and higher CH4 selectivity. Chapter 5 concludes the thesis by summarizing the key findings and providing an outlook on future research prospects in the field.