Efficient scale-up synthesis and hydrogen separation of hollow fiber DD3R zeolite membranes

Efficient hydrogen (H₂) separation is highly desired from the cracked tail gas of ethylene plant. In this work, DD3R zeolite membranes have been evaluated for potential application in H₂ separation under harsh conditions. We developed an efficient scale-up synthesis of hollow fiber DD3R zeolite membranes. The alkalinity of synthesis solution was optimized to endow the good reproducibility of high-quality membranes. 17 pieces of separate membranes, total 406 cm², were synthesized in one autoclave using the industrial grade agents. Typically, the 25 cm long membrane showed CO₂/CH₄ selectivity of 447 and CO₂ permeance of 1.55×10⁻⁷ mol m⁻² s⁻¹ Pa⁻¹. The single component permeance of H₂ is 1.8 × 10⁻⁸ mol m⁻² s⁻¹ Pa⁻¹ at 303 K and feed pressure of 0.4 MPa, leading to the ideal selectivity of 124 for H₂/CH₄, 242 for H₂/C₂H₄ and 424 for H₂/C₂H₆. For the simulated cracked gas, H₂ permeance and H₂/CH₄ separation selectivity was 1.25 × 10⁻⁸ mol m⁻² s⁻¹ Pa⁻¹ and 128, respectively. More importantly, the DD3R zeolite membrane was stable for more than 1000 h in the simulated cracked gas containing 100 ppm H₂S. Together with the linear increase of H₂ flux and H₂/CH₄ separation selectivity of 50 at high pressure of 2.1 MPa, DD3R zeolite membranes pave the way to H₂ separation from ethylene industry.