Enhanced Precombustion Capture of Carbon Dioxide by Gas Hydrate Formation in Water-in-Oil Emulsions

Abstract

In this work, we reported enhanced kinetics of gas hydrate formation in water-in-oil (W/O) emulsions for the precombustion capture of carbon dioxide. The experiments were carried out at 274.2 K and in the pressure range of 3.0–6.0 MPa. The parameters of induction time, gas uptake, rate of hydrate growth, CO2 recovery, and separation factor were determined to evaluate the performance of the W/O emulsions for CO2 capture from a fuel gas (40 mol % CO2/H2). It was found that shorter induction time and higher gas uptake were obtained while the water–oil volume ratio (WOR) was reduced from 70% to 20%, and gas hydrates were observed to grow faster at low WORs. The CO2 recovery and CO2 concentration in the hydrate phase decreased with WOR decreasing from 70% to 20%. At a fixed WOR, higher pressure resulted in shorter induction time and higher gas uptake, but CO2 concentration in the hydrate phase decreased. The highest value of CO2 concentration in the hydrate phase achieved 84 mol % at 3.0 MPa and WOR = 70%, and the highest value of gas uptake obtained in W/O emulsions was 39.5 mmol of gas/mol of water at 3.0 MPa and WOR = 20%. This gas uptake was much higher than that obtained in stirred reactors in the presence of CP or THF and was comparable with that obtained in the fixed bed of silica sand in the presence of THF or TBAB. The result indicated that the W/O emulsions employed in this work are a viable option to enhance hydrate formation for the precombustion capture of carbon dioxide.