Adsorption of propane, propylene and isobutane on a metal–organic framework: molecular simulation and experiment

Nabil Lamia, Miguel Jorge, Miguel A. Granato, Filipe A. Almeida Paz, Hubert Chevreau, Alirio E. Rodrigues

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158 Citations (Scopus)
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Abstract

The separation of propane/propylene mixtures is the most energy-intensive operation practiced in the petrochemical industry. Adsorptive processes are currently viewed as a promising alternative to cryogenic distillation for the separation of these mixtures. In this paper, we explore the possibility of using a new metal-organic framework material, CuBTC, in adsorptive separation processes, particularly in a simulated moving bed (SMB) context using isobutane as a potential desorbent. A gravimetric method has been used to measure the adsorption equilibrium isotherms of propylene, propane and isobutane onto a commercial CuBTC powder over a temperature range from 323 to 423K and pressures up to 100kPa. These were complemented by a detailed experimental characterization of the structure of CuBTC using XRD and SEM techniques. Comparison of experimental isotherms with grand canonical Monte Carlo simulations in CuBTC showed that propane adsorption occurs preferentially in small octahedral pockets, while isobutame is excluded from these pockets due to its bulky structure. Propylene was seen to interact strongly with unsaturated metal sites, due to specific pi-Cu bonds. These interactions significantly enhance the affinity of this MOF for unsaturated hydrocarbons. Furthermore, in a range of temperatures and pressures, the affinity of CuBTC for isobutane is intermediate to that of propane and propylene. Our results suggest that CuBTC-isobutane is a very promising adsorbent-desorbent pair for use in SMB processes for propane/propylene separations. 

Original languageEnglish
Pages (from-to)3246-3259
Number of pages14
JournalChemical Engineering Science
Volume64
Issue number14
DOIs
Publication statusPublished - 15 Jul 2009

Keywords

  • adsorption
  • propane
  • propylene
  • isobutane
  • metal-organic framework
  • molecular simulation
  • experiment

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