Nanocatalyst development and improvement for CO2 conversion

Abstract

As the excessive presence of CO2 continues to infiltrate the Earth's atmosphere, a very crucial mitigation strategy is to convert CO2 via hydrogenation to generate more useful fuels and chemicals such as CO and CH4. This process is easily accelerated by using a catalyst. Our research decided upon a Ru/CNS-APF (in-situ) nano-catalyst, in which ruthenium metal was dispersed over carbon nanospheres derived from 3-aminophenol and synthesised by a direct in-situ method. The strong presence of C–N combined with Ru made the CO2–H interaction easier, while the in-situ synthesis method enabled high dispersion of small Ru nanoparticles, thereby increasing the active site surface area and reducing chances of active site agglomeration. The results revealed high CO2 conversion and CO selectivity from this strong synergy, with no major structural changes. Density Functional Theory models were then built based on the results to elucidate possible CO2 hydrogenation reaction pathways on the Ru/C–N catalyst. The differences between the activities of a pure Ruthenium surface (direct CO2 dissociation) and Ru/C–N (trans-COOH) are suggested to be due to the stronger electron transfer from Ru to C–N and low coordination number of Ru altering the adsorption strength of and interactions between reaction intermediate atoms and molecules. An economic analysis also revealed that after optimising the system to include separation and recycling and by reducing the feed ratio to 1:1, CO production cost becomes 0.36 USD kg-1, considerably lower than the current market price (0.55 USD kg-1). The analysis proved that Ru/C–N-based catalysts are highly capable and affordable towards addressing the global climate challenge. Further research should consider including additional catalytic materials and structural variations, longer stability tests, more DFT reaction models to account for entropy optimisation, and additional considerations to enhance the accuracy of the economic model.