Development and Characterization of a Novel
Ceramic Membrane for
CO2 Separation in
Inclusive Dates: 04/01/10 Current
Background - Carbon dioxide emission from coal-fired power plants constitutes a large portion (~40 percent) of total CO2 emission to the environment. The cost, or energy penalty, for CO2 emission prevention (usually called carbon capture and sequestration in the literature) can be up to 50 percent of energy budget of a power plant. The major portion for the penalty for CCS is the energy wasted in cooling the flue gas (typically up to 750 °C) to a low temperature (100 to 300 °C), tolerable to the CO2 separation system. Considering that using absorbents for CO2 capture requires sophisticated engineering for the adsorption and regeneration cycles, membrane technology provides an attractive CCS alternative. However, to date no commercially available membrane system exists that can effectively and economically capture CO2 at high temperature. These facts motivate the present research effort to identify a workable membrane system for CO2 capture at high temperature. This project is anticipated to deliver an economic solution for the CO2 separation market to minimize the energy penalty, possibly down to 20 percent to 30 percent of power plant output from the current estimates of 40 percent to 50 percent.
Approach - A novel lithium metal oxide-based CO2 separation ceramic membrane is proposed. The novel aspects include (1) use of porous ceramic substrate and lithium metal oxide solid sorbents allowing operation in the 500 to 700 °C range, (2) a dual-phase system consisting of a solid framework and molten carbonate outer layers on the sorbents facilitating CO2 diffusion, (3) a thin, dense, metal oxide interlayer between the sorbent and the substrate forming a barrier to prevent any other gases except CO2 from transporting through the membrane, and (4) a ceramic inert metal oxide layer deposited on the dual phase lithium metal oxide sorbent framework improving the mechanical strength of the membrane. This novel membrane is fabricated by spray- and plasma-deposition methods, as illustrated in Figure 1. With an integrated approach of identifying new materials, economic production methodologies, engineering process, and performance evaluation of the membrane system, the project is anticipated to deliver a radically improved solution for CO2 separation from flue gas at existing coal-fired power plants and the new Integrated Gasification Combined Cycle (IGCC) power plants. The project will also develop testing methodologies to prove the function of the candidate membranes.
Accomplishments - In the first two quarters of the project, the synthesis and characterization of the novel metal oxide sorbent have been completed. The efforts in the next two quarters will focus on deposition methodologies and testing the fabricated membrane. An intellectual property filing, "Composition and Fabrication Process for High Temperature CO2 Separation Ceramic Membrane," was submitted May 18, 2010.