Development of Innovative Gas Separation Membranes through Sub - Nanoscale Material

New membrane types with well-controlled sub-nanostructures were developed from both polymeric and inorganic materials: carbon-based membranes, functionalized mesoporous oxide membranes and molecular sieving zeolite membranes. Regarding the carbon membranes, a novel carbon membrane with enhanced CO2 affinity was developed. The prepared membrane had a higher separation performance than that of the original carbon membrane in the separation of CO2/N2 mixtures under humid conditions. In addition, a method to control the sizes of subnano pores of the carbon membrane was developed. Regarding the inorganic membranes, various kinds of high silica zeolites were prepared. It was found that zeolites with a high pore volume had high CO2 adsorption capacity. We proposed a novel method for the synthesis of the composite layer of zeolite and the porous substrate; i.e., a melt-filling method. It was revealed that CO2 separation selectivity increased after the treatment. From the XRD measurement, it was revealed that the composite layer of zeolite and the porous substrate was successfully prepared without experiencing phase transition or byproduct formation after the treatment. In addition, we found the functionalization of the pore walls of mesoporous silicas by compounds with high amine density is effective in the separation of CO2. Introduction Carbon dioxide capture and storage (CCS) could allow the utilization of abundant fossil fuel reserves, while significantly decreasing emissions of CO2 to the atmosphere. However, the cost of CCS, especially of CO2 capture, is still too expensive for CCS to be considered as a cost effective technique. This project intends to develop a variety of efficient, low-cost polymeric and inorganic CO2 separation membranes as a game changing technology. Material structure engineering on the scale of gas molecules will be used to increase the permeability and selectivity of the membrane. Regarding the polymeric based materials, a cardo polymer-based carbon membrane incorporating