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Oxygen-Selective Adsorption in RPM3-Zn Metal Organic Framework
Chemical Engineering Science
  • Cheng Yu Wang
  • Linxi Wang
  • Andrew Belnick
  • Hao Wang
  • Jing I. Li
  • Angela D. Lueking, Missouri University of Science and Technology

Development of an oxygen selective adsorbent is anticipated to reduce the material and energy requirements for adsorptive separations of air by a factor of four, due to the relative concentrations of N2 and O2 in air, thereby decreasing the parasitic energy losses, carbon dioxide emissions, and cost of oxygen purification via pressure-swing adsorption. Here, we report that RPM3-Zn (a.k.a. Zn2(bpdc)<2(bpee); bpdc = 4,4'-biphenyldicarboxylate; bpee = 1,2-bipyridylethene) is oxygen selective over nitrogen at temperatures from 77 K to 273 K, although the oxygen capacity of the sorbent decreased markedly at increasing temperatures. Due to an oxygen diffusivity that is ∼1000-fold greater than nitrogen, the effective oxygen selectivity increases to near infinity at low temperature at equal contact times due to N2 mass transfer limitations for gate-opening. The kinetic limitation for N2 to open the structure has a sharp temperature dependence, suggesting this effective kinetic selectivity may be "tuned in" for other flexible metal-organic-frameworks. Although the low temperature oxygen selectivity is not practical to displace cryogenic distillation, the results suggest a new mechanism for tailoring materials for kinetic selectivity, namely, capitalizing upon the delayed opening process for a particular gas relative to another.

Chemical and Biochemical Engineering
Keywords and Phrases
  • Air cleaners,
  • Air purification,
  • Carbon,
  • Carbon dioxide,
  • Crystalline materials,
  • Distillation,
  • Energy dissipation,
  • Global warming,
  • Kinetics,
  • Mass transfer,
  • Nitrogen,
  • Organic polymers,
  • Organometallics,
  • Oxygen,
  • Temperature,
  • Temperature distribution,
  • Zinc,
  • Air separation,
  • Carbon dioxide emissions,
  • Cryogenic distillations,
  • Gate openings,
  • Kinetic selectivity,
  • Mass transfer limitation,
  • Metal organic framework,
  • Pressure swing adsorption,
  • Gas adsorption,
  • Air separation,
  • Kinetic selectivity,
  • RPM3-Zn
Document Type
Article - Journal
Document Version
File Type
© 2017 Elsevier, All rights reserved.
Publication Date
Citation Information
Cheng Yu Wang, Linxi Wang, Andrew Belnick, Hao Wang, et al.. "Oxygen-Selective Adsorption in RPM3-Zn Metal Organic Framework" Chemical Engineering Science Vol. 165 (2017) p. 122 - 130 ISSN: 0009-2509
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