Graphene-based Membranes for H2 Separation: Recent Progress and Future Perspective

Abstract

Hydrogen (H2) is an industrial gas that has showcased its importance in several well-known processes such as ammonia, methanol and steel productions, as well as in petrochemical industries. Besides, there is a growing interest in H2 production and purification owing to the global efforts to minimize the emission of greenhouse gases. Nevertheless, H2 which is produced synthetically is expected to contain other impurities and unreacted substituents (e.g., carbon dioxide, CO2; nitrogen, N2 and methane, CH4), such that subsequent purification steps are typically required for practical applications. In this context, membrane-based separation has attracted a vast amount of interest due to its desirable advantages over conventional separation processes, such as the ease of operation, low energy consumption and small plant footprint. Efforts have also been made for the development of high-performance membranes that can overcome the limitations of conventional polymer membranes. In particular, the studies on graphene-based membranes have been actively conducted most recently, showcasing outstanding H2-separation performances. This review focuses on the recent progress and potential challenges in graphene-based membranes for H2 purification.

Electro-Persulfate Processes for the Treatment of Complex Wastewater Matrices: Present and Future

“…Another possibility to solve the problem raised by the limitation in mass transfer is to improve reactor configuration and, recently, reactive electrochemical membranes are being utilized as a flow-through electrode. These electrochemical membranes significantly increase the active surface area, while enhancing pollutants mass transport by convection [ 44 , 45 , 46 ].…”

Recent Progress in Mixed-Matrix Membranes for Hydrogen Separation

“…CO molecules that are generated can be further converted to additional H 2 by a water-gas shift (WGS) reaction as illustrated in Equation (2). Despite SMR being widely used today, the large CO 2 emission, amounting to 830 million tons annually, is a major drawback in light of the current concern over global warming and climate change [19,23]. Thus, downstream carbon capture, sequestration and utilization are an important piece of the puzzle in realizing blue hydrogen production by SMR technology.…”

“…Hydrogen is not an extractable resource, but created via synthetic means and separated from other elements before producing in its pure form [ 19 ]. Essentially, steam-methane reforming (SMR), partial oxidation (POX), gasification and electrolysis are currently the mainstream technologies available for hydrogen generation, with a market share of 48%, 30%, 4% and 18%, respectively, as cited in 2012 [ 20 ].…”

“…PSA involves the utilization of micro- and mesoporous solid adsorbents (e.g., zeolites, activated carbons, alumina and silica gels) that are packed in an adsorption column for separation. Due to the small polarizability and quadrupole moment of hydrogen gas in comparison to other impurities such as carbon dioxide (CO 2 ), nitrogen (N 2 ) and methane (CH 4 ), a pressurized gas feed up to 40 bar is necessary to induce effective adsorption of polarizable gas impurities by the adsorbents [ 19 , 37 ]. High-pressure hydrogen, which cannot be adsorbed, will be recovered at the top of the adsorption columns.…”

Membranes for Water, Gas and Ion Separation

“…Chuah et al [ 4 ] reviewed graphene-based membranes for hydrogen separation. Hydrogen is an important industrial gas that has attracted attention as a carbon-free energy resource with the highest energy density per unit mass.…”