Catalytic enhancement of hydration of CO₂ using nickel nanoparticles for carbon capture and storage

PhD ThesisThe capture and storage of atmospheric CO2 as mineral carbonates, is one of the safest ways to combat global warming. The slow CO2 hydration rate is one limitation of the mineralization process. The current study presents the discovery of nickel nanoparticles (NiNPs) as a catalyst for enhancing the rate of CO2 hydration for mineralization carbon capture and storage. The NiNPs at an optimum concentration of 30 ppm, increased the saturation concentration by three folds as compared with deionized water alone. The mechanism of the reaction on NiNPs surface is also proposed. The kinetics of catalysis of CO2 hydration was additionally studied using stopped flow spectrophotometery and pH changes in buffer solution upon addition of saturated CO2 solution. To distinguish between physical gas-liquid transfer and catalysis, other inorganic nanoparticles (NiO and Fe2O3) have been studied. The effect of CO2 partial pressure on NiNPs catalysis was studied. Nickel nanowires (NiNWs) were synthesised and tested for catalysis of CO2 hydration. The photocatalytic activity of NiNPs was evaluated under artificial solar irradiation compared with that in the dark. The results suggest that the surface plasmonic resonance (SPR) of NiNPs enhances the rate of water dissociation on the NiNPs surface leading to higher rate of CO2 hydration under solar irradiation. The effect of temperature on the catalytic activity of NiNPs is evaluated. Optimum activity was observed at room temperature (20-30 °C). Application of NiNPs catalysis was investigated for CaCO3 precipitation and the rate of CO2 absorption in 50 wt% carbonate solutions. Vapour-liquid equilibrium studies of CO2-H2O in presence of nanoparticles (Ni, Fe2O3 and NiO) found that ii the presence of nanoparticles decreases the surface tension of DI water, responsible for the increase in CO2 saturation concentration. Additionally a novel method for mineralization of CO2 using gypsum and sodium chloride was developed including design of a customized reactor