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 CO ₂ 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/H ₂ separation agent and provides the knowledge needed for further demonstration of the nanoporous TiO₂-based pre-combustion CO ₂ separation technology.