Single Column VSA Studies for CO2 Recovery Using Metal Organic Frame Work Adsorbent: Comparison with Commercial Zeolite

Single Column VSA Studies for CO₂ Recovery using Metal Organic Frame Work Adsorbent: Comparison with Commercial Zeolite

 

Aarti Arya, Soumen Dasgupta, Swapnil Divekar, Anshu Nanoti*, Amar N. Goswami and Madhukar O. Garg

Indian Institute of Petroleum, Dehradun-248005, India.

Anne Andersen, Jasmina Hafizovic Cavka & Richard Blom

SINTEF Materials & Chemistry, P.O.Box 124 Blindern, 0314 Oslo, Norway

Rising levels of CO₂ in the atmosphere due to burning of fossil fuel have been recognized to be the main contributor of global warming and associated climate change phenomenon.  Fossil fuel combustion for power generation is the major source of increased CO₂ levels in the atmosphere, but capturing CO₂ from flue gas emissions in power plants where it is available as a low pressure stream, presents a formidable challenge. Current technologies available such as amine based absorption processes are considered uneconomic and there is a concerted effort being made to improve such processes or develop more efficient alternative processes. In this context adsorption processes using Pressure or Vacuum Swing Adsorption (PSA/VSA) are attracting interest as energy requirements are lower [1].

Solid adsorbents like zeolites and activated carbons can be used to recover CO₂ from flue gas mixtures by pressure swing adsorption technique.Several adsorbent materials have been investigated for CO₂ recovery by PSA/VSA. The general consensus appears to be that Zeolite 13X materials performs better than activated carbons or silica gels [2][3]. Both capacities and selectivities for separation of CO₂/N₂ mixtures (representative of flue gases from power plants) are superior. However, as CO₂ isotherms on zeolites are nonlinear, power requirement during regeneration can be high and there is for this reason a large scope for developing new adsorbents which will show better selectivity and regenerability.

Metal Organic Frameworks (MOF) is a new class of adsorbents   attracting interest for selective CO₂ separation [4][5]. These are materials in which metal ions or clusters are connected via organic linkers to form highly porous network structures. Several MOF's have been proposed as adsorbents for CO₂ recovery. These include  MOF-47  [Vanadium (IV) benzene 1,4 dicarboxylate ], MIL-53 [Chromium (III) benzene 1,4 dicarboxylate]  and CuBTC [ Copper(II) benzene 1,3,5 tri carboxylate]. However, the several studies that have been reported so far on CO₂ adsorption on MOF's have been limited mostly to equilibrium isotherm and diffusion measurements with pure components [6,7,8,9]. The present paper  reports an experimental study on the separation of CO₂ from mixtures with nitrogen using UIO-66 (Zr₆O₄(OH)₄(1,4-dicarboxybenzene))MOF adsorbent [10], in a vacuum swing adsorber operating with a heavy reflux or rinse cycle typically used for recovery of the strong adsorptive (in this case, CO₂) from gas mixtures. UIO-66 is an in-house synthesised MOF that can be formulated easily in suitable forms for column operation. The results are compared with performance data generated with commercialZeolite 13X under comparable operating conditions. The study shows that UIO-66 performs satisfactorily in long term column operation and there was no performance deterioration noted. CO₂ recoveries are higher than observed with the zeolite while CO₂ purities are lower.

*Corresponding author

References:

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