Tailor-Made Modification of Commercial Ceramic Membranes for Environmental and Energy-Oriented Gas Separation...

Ceramic membranes have been considered as potential candidates for several gas separation processes of industrial interest, due to their increased thermal and chemical stability compared to polymeric ones. In the present study, commercial Hybrid Silica (HybSi^®) membranes have been evaluated and modified accordingly, to enhance their gas separation performance for targeted applications, including CO₂ removal from flue gas and H₂ recovery from hydrogen-containing natural gas streams. The developed membranes have been characterized before and after modification by relative permeability, single gas permeation, and equimolar separation tests of the respective gas mixtures. The modification procedures, involving in situ chemical vapor deposition and superficial functionalization, aim for precise control of the membranes' pore size and surface chemistry. High performance membranes have been successfully developed, presenting an increase in H₂/CH₄ permselectivity from 12.8 to 45.6 at 250 °C. Ultimately, the modified HybSi^® membrane exhibits a promising separation performance at 250 °C, and 5 bar feed pressure, obtaining above 92% H₂ purity in the product stream combined with a notable H₂ recovery of 65%, which can be further improved if a vacuum is applied on the permeate side, leading to 94.3% H₂ purity and 69% H₂ recovery.