Hydrogen permselective membrane prepared by plasma treatment of porous ceramic substrates

Demand for hydrogen is increasing as we move toward a decarbonized society. Membrane separation methods have attracted attention as a way to reduce the cost of hydrogen production. In this study, we focused on boron nitride (BN) as a chemically stable porous substrate material. CVD treatment at 250°C has been investigated for porous BN, but selectivity did not develop. Therefore, we focused on atmospheric pressure plasma as a treatment method. The objective of this study is to develop a membrane with high hydrogen selective permeance by immersion in silicon alkoxide after plasma treatment. After plasma treatment for 100 s, the H 2 permeance was 3.52×10 −6 [mol m −2 s −1 Pa −1 ] and the H 2 /N 2 permeance ratio was 18.25. Since molecular hydrogen can pass between the BN crystal faces, it is considered that silica reacted with the hydroxy groups formed on BN by plasma treatment and blocked the space between crystals. Therefore, it is suggested that the performance of the separation membrane changes depending on the number and distribution of hydroxyl groups by plasma treatment, and further stabilization is needed.