Browsing by Author "Mouchaham, Georges"
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- Green Hydrogen Recovery from Natural Gas Grids by Vacuum Pressure Swing AdsorptionPublication . Zafanelli, Lucas F.A.S.; Aly, Ezzeldin; Henrique, Adriano; Rodrigues, Alírio; Mouchaham, Georges; Silva, José A.C.This study focuses on the development of a conceptual vacuum pressure swing adsorption process (VPSA) for green hydrogen (GH) recovery from natural gas grids (NGGs). Accordingly, the kinetics-based separation of H-2 from NGG was achieved by using a commercial carbon molecular sieve (CMS-3K-172) adsorbent. To develop the VPSA cycle, the CMS-3K-172 was characterized, single- and multicomponent breakthrough curves for H-2 and CH4 were performed, and adsorption isotherms were collected between 195 and 273 K and pressures up to 18 bar. To separate H-2 (20%) from CH4 (80%), three different VPSA cycle configurations were designed and simulated by using Aspen Adsorption. The operational variables, such as step times, intermediate-to-high-pressure ratio, purge-to-feed ratio, and H-2 initial concentration, were evaluated for maximum values of purity, recovery, and adsorbent productivity. The results show that the VPSA processes can enrich H-2 in the product stream by up to 68% with a recovery of 92%.
- Kinetic separation of green hydrogen from natural gas grids by using vacuum pressure swing adsorptionPublication . Zafanelli, Lucas F.A.S.; Henrique, Adriano; Aly, Ezzeldin; Rodrigues, Alírio; Mouchaham, Georges; Silva, José A.C.Transitioning to renewable energy sources is crucial to mitigating climate change. In this scenario, green hydrogen (GH) is considered a promising energy carrier due to its high calorific value, versatility in applications, clean combustion, and potential for local generation in abundance. As interest in GH grows, developing its distribution chain becomes crucial in facilitating its widespread use. The co-transporting GH into existing natural gas grids (NGG) emerges as a viable alternative, eliminating the need for significant infrastructure investments. However, upon blending GH into the NGG, it becomes essential to de-blend and purify it to a high degree to enable, for instance, fuel cell applications (H2 > 99,97%). One problem concerning the separation and purification of GH from NGG relates to the H2 feed concentration (< 20%), which differs significantly from conventional H2 purification processes (> 70%). Moreover, the high CH4 concentration and its relatively weak adsorption affinity on commonly used adsorbents further complicate achieving high-purity H2 and high recovery rates through conventional approaches. In this work, we report a novel conceptual vacuum pressure swing adsorption (VPSA) process to separate H2 from CH4 by exploiting the kinetic selectivity of H2 over CH4 on CMS-3K-172.
- Novel vacuum pressure swing adsorption for green hydrogen recovery from natural gas grids using carbon molecular sievePublication . Zafanelli, Lucas F.A.S.; Aly, Ezzeldin; Henrique, Adriano; Rodrigues, Alírio; Mouchaham, Georges; Silva, José A.C.This work shows for the first time that an adsorbent that adsorbs preferentially H2 and blocks CH4 from entering its pores can be useful to enrich H2 from a low feed concentration. Moreover, this work provides insights for developing new materials with the same CMS characteristics but with higher H2 capacity, which could be beneficial to improve the VPSA process. In conclusion, the developed VPSA process is useful for increasing the H2 molar fraction from 20% to 60 - 70% with a high recovery. We are currently working on a second stage to be incorporated into the VPSA process to purify H2 for fuel cell applications (>99.97%).