Use of a Robust and Inexpensive Nanoporous TiO2 for Pre-combustion CO2 Separation

The objective of this research is to study the performance of an inexpensive high-surface-area nanoporous titanium oxide (TiO2) on the CO2/H2 separation and resulting pre-combustion CO2 capture. The experiments were carried out at different temperatures (25, 50, 75, 100, and 125 °C) and pressures (5, 10, 15, 20, 25, 30, and 35 bar) using a fixed-bed adsorber. The data obtained for the pure component isotherms and binary gas mixtures were correlated using Sips and Langmuir–Freundlich binary-component-expanded isotherm adsorption (LFBE) models, respectively. Also, the deactivation model was used to simulate the observed CO2 sorption breakthrough curves. Experimental results show that the capture capacities of the sorbent for both H2 and CO2 were improved with the increase in the pressure and decrease in the temperature. The maximum sorption capacities for pure CO2 and H2 were found to be 14.4 and 5.2 mmol/g of TiO2 at 35 bar and 25 °C, respectively. The increase in the temperature and decrease in the pressure improve the sorption selectivity of TiO2 for CO2. The selectivity value of TiO2 reached 9.87 at 125 °C and 5 bar for a CO2/H2 molar ratio of 50:50. TiO2 also shows great stability and regenerability. This study indicates that nanoporous TiO2 is potentially a cost-effective and robust CO2/H2 separation agent and provides the knowledge needed for further demonstration of the nanoporous TiO2-based pre-combustion CO2 separation technology.