High-performance hydrogen separation using cellulose-based carbon molecular sieve membranes

Cellulose-based carbon molecular sieve membranes were designed for hydrogen deblending from natural gas and hydrogen recovery from other relevant industrial sources. The crystallinity of the cellulose precursor was increased by adding propylene glycol, which originated a carbon membrane with a permeability to the hydrogen of 544 barrer and an H-2/CH4 permselectivity of ca. 3500 (Robeson index = 100). A careful optimization of the carbonization conditions of the cellulose precursor boosted the carbon membrane permeability to hydrogen to 1144 barrer and the H-2/CH4 permselectivity to 1080 (Robeson index = 62). The membrane with the highest permeability to hydrogen presented the highest micropore volume of 0.443 cm(3)g(-1) and a micropore surface area of 1326 m(2)g(-1). A detailed techno-economic analysis of the hydrogen recovery from the natural gas was performed. It was concluded that a single-stage carbon membrane module can recover hydrogen with a concentration of 99.8 % and a specific cost of 0.26 kgH(2)(-1) for a hydrogen recovery of 68 %. A two-stage membrane process was simulated to deliver a purity >99.997 % and a recovery of 96 %, with a specific cost of 1.8 kgH(2)(-1). The carbon membranes prepared in this work are highly competitive with other separation processes for the recovery and purification of hydrogen from different industrial processes essential for the decarbonization.