A new technology for pre-combustion Co2 separation.

摘要

The first part of this thesis provides a comprehensive assessment of recently improved carbon dioxide (CO2) separation and capture systems, used at power plants and other industrial processes. Different approaches for CO2 capture are pre-combustion, post-combustion capture, and oxy-combustion systems, which are reviewed, along with their advantages and disadvantages. New technologies and prospective "breakthrough technologies", for instance: novel solvents, sorbents, and membranes for gas separation are examined. Other technologies including chemical looping technology (reaction between metal oxides and fuels, creating metal particles, carbon dioxide, and water vapor) and cryogenic separation processes (based on different phase change temperatures for various gases to separate them) are reviewed as well. Furthermore, the major CO2 separation technologies, such as absorption (using a liquid solvent to absorb the CO2), adsorption (using solid materials with surface affinity to CO2 molecules), and membranes (using a thin film to selectively permeate gases) are extensively discussed, though issues and technologies related to CO2 transport and storage are not considered in this paper.;The objective of the second part 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) by 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 utilized to simulate the observed CO 2 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-TiO2 at 35 bar and 25°C, respectively. The increase in temperature and decrease in pressure, improve the sorption selectivity of TiO2 for CO2. The selectivity value of TiO2 reached 9.87 at 125°C and 5 bar for 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.