Ultrahigh permeance metal coated porous graphene membranes with tunable gas selectivities

• Published in: Chem Vol. 7; no. 9; pp. 2385 - 2394
• Main Authors: Ashirov, Timur, Coskun, Ali
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 09.09.2021
• Subjects: adsorptive separation; H2/CO2 separation; He/H2 separation; porous graphene-based membranes; ultrahigh permeance; adsorptive separation; porous graphene-based membranes; H2/CO2 separation; SDG13: Climate action; SDG7: Affordable and clean energy; ultrahigh permeance; He/H2 separation
• ISSN: 2451-9294; 2451-9294
• DOI: 10.1016/j.chempr.2021.06.005

Membranes play an important role in gas separation on account of their low cost, energy efficiency, and durability. Gas-separation membranes, however, are subject to permeability-selectivity trade-off, i.e., atomically thin 2D materials such as porous graphene can provide ultrahigh permeances in the range of ∼105–107 GPU but suffer from low gas selectivity. Here, we show a new concept to enhance the selectivity of graphene-based membranes by employing adsorptive separation for binary gas mixtures. The deposition of “microislands” of Pd and Ni on the porous double-layer graphene support allowed us to selectively target H2 in He/H2 and CO2 in H2/CO2 mixtures, respectively, thus enabling efficient separation of He and also leading to the highest H2/CO2 separation factor of 26 within the ∼105 GPU permeance range. Moreover, the selective targeting of individual gases in a membrane setting through adsorptive separation at room temperature can be a promising alternative for economical gas separation. [Display omitted] •Tuning the transport properties of an individual gas in a binary gas mixture•Highly efficient steady-state H2/CO2 and adsorptive separation of He/H2 gas mixtures•Applicability to the separation of various gas mixtures using a suitable metal layer•The highest H2/CO2 separation factor of 26 in the 105 GPU permeance range Membranes are important in gas-separation applications due to their high energy efficiency, low operational costs, and durability. They are, however, subject to a permeability-selectivity trade-off, i.e., membranes with high permeability (fast flow rate) have low selectivity (low separation capability) and vice versa. In order to simultaneously achieve high selectivity and permeance, membranes that do not obey a simple trade-off rule would be required. In this direction, the concept of adsorptive separation can enhance membrane selectivity by individually targeting a single gas in a mixture while retaining high permeance. In this study, we demonstrated highly efficient adsorptive separation of He/H2 and steady-state separation of H2/CO2 with the highest H2/CO2 separation factor of 26 within the ultrahigh permeance range by depositing microislands of Pd and Ni to target H2 and CO2, respectively, thus offering promising alternatives for energy-efficient, cost-effective gas separation. We demonstrate the template-assisted, uniform deposition of microislands of Pd and Ni onto the porous double-layer graphene in order to selectively target H2 and CO2 in He/H2 in a CO2/H2 gas mixtures, respectively. These membranes enabled highly selective gas separation in the ultrahigh permeance range, thus offering promising alternatives for membrane gas-separation applications.