Investigation on CO₂ Hydrate Formation Promoted by Combination of Nanoparticles AlO(OH), ZnO, and TBAB

To effectively address global climate change and achieve China’s long-term goals of “Carbon peaking” and “Carbon neutrality,” it is imperative to reduce and control greenhouse gas emissions, particularly carbon dioxide (CO2). Presently, emerging hydrate-based CO2 capture technology has become a research focus. However, the long induction time and slow formation rate of CO2 hydrate limit the industrial application of this method. To address this problem, the promotional effects of different concentrations of AlO(OH) and ZnO nanoparticles combined with tetrabutylammonium bromide (TBAB) on hydrate formation kinetics at temperatures of 274.15 and 275.15 K were investigated. Experimental results showed that the 0.1 wt % ZnO system had the shortest induction time of 5.2 min at 274.15 K, which was 82.1% shorter than that of pure water, while the 5 wt % TBAB system produced the highest hydrate production amounts of 0.151 mol at 275.15 K, which was 69.7% higher than that of pure water. The combination systems exhibited a more profound promotional effect on shortening induction time and increasing yield compared to any single promoter. Among them, the 5 wt % TBAB + 0.2 wt % ZnO system exhibited the shortest induction time of 5.67 min and the highest yield of 0.164 mol. This study also displays that the presence of nanoparticles provides numerous nucleation sites for hydrate formation by generating heterogeneous hydrate nuclei, and the considerably large specific surface areas of nanoparticles enhance mass transfer between gas and liquid phases, ultimately increasing hydrate yield. These research results provide the optimal concentration of different promoters under various formation conditions, providing theoretical guidance for future large-scale industrial applications of hydrate-based CO2 capture.