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Optimisation of Cu + impregnation of MOF-74 to improve CO/N2 and CO/CO2 separations

DOI: 10.1039/C9RA10115B DOI Help

Authors: Arwyn Evans (Imperial College London) , Matthew Cummings (The University of Manchester) , Donato Decarolis (Imperial College London) , Diego Gianolio (Diamond Light Source) , Salman Shahid (Imperial College London) , Gareth Law (The University of Manchester) , Martin Attfield (The University of Manchester) , David Law (BP Chemicals Ltd Petrochemicals Technology) , Camille Petit (Imperial College London)
Co-authored by industrial partner: Yes

Type: Journal Paper
Journal: Rsc Advances , VOL 10 , PAGES 5152 - 5162

State: Published (Approved)
Published: January 2020
Diamond Proposal Number(s): 18788

Open Access Open Access

Abstract: Carbon monoxide (CO) purification from syngas impurities is a highly energy and cost intensive process. Adsorption separation using metal–organic frameworks (MOFs) is being explored as an alternative technology for CO/nitrogen (N2) and CO/carbon dioxide (CO2) separation. Currently, MOFs' uptake and selectivity levels do not justify displacement of the current commercially available technologies. Herein, we have impregnated a leading MOF candidate for CO purification, i.e. M-MOF-74 (M = Co or Ni), with Cu+ sites. Cu+ allows strong π-complexation from the 3d electrons with CO, potentially enhancing the separation performance. We have optimised the Cu loading procedure and confirmed the presence of the Cu+ sites using X-ray absorption fine structure analysis (XAFS). In situ XAFS and diffuse reflectance infrared Fourier Transform spectroscopy analyses have demonstrated Cu+–CO binding. The dynamic breakthrough measurements showed an improvement in CO/N2 and CO/CO2 separations upon Cu impregnation. This is because Cu sites do not block the MOF metal sites but rather increase the number of sites available for interactions with CO, and decrease the surface area/porosity available for adsorption of the lighter component.

Diamond Keywords: Gas Separation

Subject Areas: Chemistry, Materials

Instruments: B18-Core EXAFS

Added On: 06/02/2020 09:50


Discipline Tags:

Chemistry Materials Science Metal-Organic Frameworks Metallurgy Organometallic Chemistry

Technical Tags:

Spectroscopy X-ray Absorption Spectroscopy (XAS) Extended X-ray Absorption Fine Structure (EXAFS)