N2-selective adsorbents and membranes for natural gas purification

A highly permeable porous organic cage composite membrane for gas separation

“…In addition, N 2 and CH 4 permeances of the composite membranes decreased substantially after the introduction of RCC3, probably because these two gases permeated through the membrane based on the surface diffusion mechanism. 11,55…”

“…5 In recent years, polymeric and inorganic membranes based on polyethylene oxide, polyvinylamine, Pebax, zeolites, and graphene were developed for gas separation, which were mainly fabricated through vacuum ltration, surface coating, in situ growth, interfacial polymerization, and electrostatic interaction. [6][7][8][9][10][11] However, only a few of them can break through the McKeown 2019 upper-bond line with a CO 2 /N 2 selectivity of 20 and CO 2 permeability of 27 738 barrer. Zhu et al 12 reported a facile one-step synthesis protocol to incorporate poly(ethylene glycol) methyl ether acrylate into the Pebax matrix via in situ polymerization, and the self-polymerized membrane exhibited excellent high gas separation performance with a CO 2 permeability up to 832 barrer and CO 2 /N 2 selectivity up to 63.5 at a high feed pressure of 20 bar.…”

Screening of Alkali Metal-Exchanged Zeolites for Nitrogen/Methane Separation

“…Natural gas, primarily composed of methane (CH 4 ), is currently one of the major energy sources in the world . Natural gas is a clean, low-carbon, high-quality fuel compared with other fossil fuels and has a wide range of industrial and domestic applications , because the combustion of gas produces 50% less carbon dioxide (CO 2 ) for the same energy output without generating particulate matters or other air pollutants. In addition to conventional gas reservoirs, natural gas is widely extracted from a range of unconventional gas resources, such as coalbed methane, landfill gas, and biogas …”

“…Alternatively, adsorption-based technology is a practical separation technique with lower energy consumption. , However, high-performance adsorbents are required for the adsorption process. , In the case of natural gas, ideally, the minor component (N 2 ) should be adsorbed over CH 4 to minimize both capital (smaller equipment is required when adsorbing minor components) and operating (the CH 4 -selective adsorption process requires its repressurizing to the pipeline pressure) costs . Most adsorbents show equilibrium selectivity toward CH 4 rather than N 2 because of the relatively higher polarizability of the former (2.448 and 1.710 Å for CH 4 and N 2 , respectively) .…”

“…13,14 In the case of natural gas, ideally, the minor component (N 2 ) should be adsorbed over CH 4 to minimize both capital (smaller equipment is required when adsorbing minor components) and operating (the CH 4selective adsorption process requires its repressurizing to the pipeline pressure) costs. 2 Most adsorbents show equilibrium selectivity toward CH 4 rather than N 2 because of the relatively higher polarizability of the former (2.448 and 1.710 Å 3 for CH 4 and N 2 , respectively). 1 Despite intensive research on adsorbents utilizing either kinetic or thermodynamic separation mechanisms, it still remains a difficult task to develop a low-cost and highly N 2 -selective adsorbent.…”