Effect of nanoparticles as a substitute for kinetic additives on the hydrate-based CO2 capture

Abstract

The greenhouse effect caused by the sharp increase in CO2 content in the atmosphere seriously threatens the ecological balance. And hydrate-based CO2 capture is a new CO2 capture and storage (CCS) technology to mitigate CO2 emission. To address complex hydrate formation conditions and low growth rate during hydrate-based CO2 capture, novel additives composed with SiO2/Al2O3 nanoparticles (NPs) and tetrabutylammonium-bromide (TBAB) were proposed under moderate conditions. The mixed additives with 10 wt% TBAB and SiO2/Al2O3 NPs could achieve a shorter induction time by 53.5% (0.2 wt% SiO2), increase gas consumption by 14.4% (0.6 wt% Al2O3), and accelerate the rate of hydrate formation by 75.8% (0.6 wt% Al2O3). Compared to the mixed additives of traditional kinetic additives (SDS and L-methionine) and TBAB, the synergistic effect of TBAB and NPs shows a high CO2 capture amount by 6.23–10.9%, reflecting the advantage of NPs as a substitute. NPs reduce the surface tension of the liquid, promoting the gas–liquid mass transfer and enhancing the heat transfer effect of the system. Raman analysis reveals NPs could strongly destruct hydrogen bonds between water molecules and effectively provide sites for heterogeneous nucleation of hydrates. Therefore, the competitive advantage of NPs in this study on CO2 capture was mainly reflected in its capture amount, which had certain benefits. This study provides a new research idea for CO2 capture by the hydrate method.