Development of carbon molecular sieve membranes for the use of renewable gases, biomethane and hydrogen in natural gas networks

The European Union (EU) is fostering cleaner energy to make EU a global leader in renewable energy and ensure that the target of at least 27% of renewables in the final energy consumption in the EU by 2030 is met. In this sense, the renewable gases, e.g., biogas and H₂, can play an important role to make the natural gas networks greener. To convert biogas into commercial grade fuel gas or biomethane, the most important operation is the separation of CO₂ and CH₄ from biogas which is carried out by technologies based on unit operations like absorption or permeation. The most used technologies are water scrubbing, pressure swing adsorption (PSA), chemical and physical scrubbing. However, these current technologies are very energy intensive and membrane technology may offer an attractive alternative in terms of capital and operating costs. To achieve optimum performance for gas separation, the membranes should both have high permeance and selectivity. Carbon Molecular Sieve Membranes (CMSM) have been identified as very promising candidates for gas separation. They offer tunable pore structure for the separation targeted and high thermal and chemical stability. CMSM are produced by the carbonization of a polymeric precursor under an inert atmosphere or vacuum. CMSM have a unique microporous structure which allows them to discriminate gas molecules by size and shape. In this presentation, the applications of CMSM in the projects BioHysis (Hybrid and flexible system for biogas upgrading for injection in natural gas grid) and HyGrid (Flexible hybrid separation system for H₂ recovery from natural gas grid) are considered. The CMSM prepared show better permeation properties than the state of the art and current commercial polymeric membranes.