Intensification of aqueous mineralisation of CO2 with CaO containing industrial wastes in a modified airlift reactor

Abstract

CO2 mineralisation is considered the safest storage medium for mitigating climate change. One of the challenges with the industrial demonstration of the mineralisation technology is reactor design. In the current study we demonstrate the use of draft tube based reactor for the mineralisation of CO2. The draft tube reactors show better performance as compared to the absence of draft tube at near ambient pressure for CO2 at different concentrations. The draft tube has been modified to increase the gas-liquid mass transfer rate by adding multi-orifice plates on top as well as increasing the solid precipitation in the reactor with a spiral flow arrangement at the bottom of the draft tube. At higher CO2 concentrations and near ambient pressures, the draft tube with modifications shows 2.5 fold enhancement in the overall rate as compared to draft tube without modifications. Additionally, at lower CO2 concentrations (i.e. near flue gas concentrations), the draft tube with modifications has better conversion capacity as compared to draft tube without modifications. This enhancement is due to the increased gas holdup and separation of solids in the draft tube with modifications. The precipitates obtained in the draft tube reactors show nanoparticles arranged in coral or mosaic arrangements as compared to the reactor without draft tube.