A New High Flux with High Selectivity Membrane for Low-Cost CO2 Capture

The electricity produced from fossil fuels is essential to the world’s prosperity and security, but the increasing atmospheric CO2 concentrations caused by the fossil fuel combustion are implicated in climate change. Although there are several methods for separating CO2 from the flue gases, all have significant drawbacks, including loss of efficiency and high capital and operating costs that dramatically increase the cost of electricity. In this SBIR project, TDA Research (TDA) is developing a new inorganic composite membrane with high flux (>1,200 GPUs) and a high selectivity (>100) for removing CO2 from flue gas. Our membrane is easily scalable and can be tuned to provide high selectivity and flux even for dilute mixtures. The membrane’s uniform pore size will also exclude potential flue gas impurities such as SO2 and NOx that are larger than N2. Thus, we have the potential to carry out multiple separation steps in a single module. The objective of the Phase I work was to synthesize various membrane samples and assess their efficacy in flue gas treatment applications such as CO2/N2 separations. We evaluated the new membranes in a bench-top test unit to determine the separation efficiency (e.g., flux and selectivity). We showed that they can achieve fluxes >1,000 and selectivity >22. We assessed the impact of key operating parameters on performance (e.g., temperature, pressure) and evaluated the life of the membrane under representative conditions. The materials used in the selective layer were shown to be stable under the presence of H2O, SO2 and NOx, the contaminants present in the flue gas. Based on the results, we carried out an engineering design and estimated the cost of carbon capture to be $31.2/tonne, approaching the 2030 DOE cost target for transformational carbon capture technologies. In the Phase II, we will continue with the membrane optimization efforts. Using the most promising candidates, we will perform long duration tests (2,000 hr minimum) to assess the chemical and mechanical stability of the membranes. We will design and build a multi-membrane prototype and perform 1,000 hr (minimum) testing with the prototype to fully demonstrate its flawless operation. Based on the experimental data, we will design the full-scale post-combustion treatment system and carry out high fidelity engineering analysis and design to assess the merits of the new technology. CO2 is a major greenhouse gas and the major source. Most of the load is the result of the combustion of fossil fuels, in particular the burning of coal to generate electricity. The proposed technology will provide a cost-effective way to control CO2 emissions. Due to the well-defined nanostructures, and myriad of chemical functionalities with the ability to molecularly- engineer these properties, our membranes can also be applied in other industrial separation processes and petrochemical applications.