Silica-based membranes show both robust properties and high-permeability, offering us great potential for applying them to harsh conditions where conventional organic membranes cannot work. Despite the increasing number of paper and patents of silica-based membranes, their industrial applications have yet to be fully realized, possibly due to their lack of technologies on scaling-up and mass production. In particular, quality of membrane supports decisively impacts final quality of silica-based separation membranes. In this study, therefore, we have developed mass producing technologies of nano-porous supports (φ 12 mm, length 400 mm) with surface center pore size distribution of 1–10 nm, which are generally used as supports for preparing separation membranes with a pore size of less than 1 nm. The developed mass production apparatuses have enabled us to reproducibly produce nano-porous silica-based supports with high permeance (e.g., N2 permeance of more than 10−5 mol m−2 s−1·Pa−1) minimizing effects of membrane defects less than 0.1% of the total flux. The developed nano-porous supports have enabled us to reproducibly produce silica-based separation membranes with high permeace and selectivity (e.g., H2 permeance of about 5 × 10−6 mol m−2 s−1 Pa−1 and H2/SF6 permeance ratio of more than 2000).
Reverse‐selective membranes, through which bigger molecules selectively permeate, are attractive for developing chemical processes utilizing hydrogen because they can maintain the high partial pressure of hydrogen required for further downstream utilization. Although several of these chemical processes are operated above 473 K, membranes with outstanding reverse‐selective separation performance at these temperatures are still to be reported. M. Matsukata et al. propose a new adsorption‐based reverse‐selective membrane that utilizes a Na cation occluded in a zeolitic framework. The membrane developed in this work enables selective permeation and separation of bigger polar molecules, such as methanol and water, from hydrogen above 473 K. For more information, see their Full Paper on page 1070 ff.magnified image
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