(102c) Using All Available Tools for Advanced Membranes for Gas Separations

Gas separations will be factors in determining long term winners from losers in the competitive global chemical industry, where large costs and savings are at stake in a competitive market. As highly energy-intensive processes, gas separations benefit from strategies that reduce energy use while minimizing capital costs needed to deliver each unit of product. Membranes are tools to implement such strategies in capacity expansions and new processes, which are enabled by approaches that were less attractive even a few decades ago. The ability to naturally incorporate molecularly-selective partitioning and diffusive discrimination between components in a single device causes membranes to be tools for process-intensification. The selective partitioning feature is understandable in terms of well-known thermodynamic factors. On the other hand, engineering the diffusion selectivity feature is a more recent tool. Examples of advanced materials, novel membrane structures and processes displaying high productivity and economical energy-efficient gas separations will be discussed. Not only engineering of diffusion activation energies but also of diffusion activation entropies associated with size-similar penetrants will be shown to be responsible for the development of these advanced tools.