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 (N) and CO/carbon dioxide (CO) 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, 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). XAFS and diffuse reflectance infrared Fourier Transform spectroscopy analyses have demonstrated Cu-CO binding. The dynamic breakthrough measurements showed an improvement in CO/N and CO/CO 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.
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http://dx.doi.org/10.1039/c9ra10115b | DOI Listing |
ACS Omega
March 2024
Department of Chemistry, University of Georgia, Athens, Georgia 30602, United States.
The structures, energetics, and energetically preferred spin states of methylphosphinidene-bridged binuclear cyclopentadienyliron carbonyl complexes MePFe(CO)Cp ( = 4, 3, 2, and 1) related to the experimentally known (μ-RP)Fe(μ-CO)(CO)Cp (R = cyclohexyl, phenyl, mesityl, and 2,4,6-tBuCH) complexes have been investigated by density functional theory. Singlet structures having a pyramidal pseudotetrahedral phosphorus environment with 18-electron iron configurations are energetically preferred in the tricarbonyl and tetracarbonyl systems MePFe(CO)Cp ( = 4 and 3) with the lowest energy structures of the tricarbonyl very closely resembling the experimentally determined structures. For the more unsaturated dicarbonyl and monocarbonyl systems MePFe(CO)Cp ( = 2 and 1), higher spin state triplet and quintet structures are energetically preferred over singlet structures.
View Article and Find Full Text PDFJ Environ Sci (China)
April 2024
Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, Nanchang Hangkong University, Nanchang 330063, China; Academy of Environmental and Resource Sciences, School of Environmental Science and Engineering, Guangdong University of Petrochemical Technology, Maoming 525000, China; College of Environmental Science and Engineering, Hunan University and Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China. Electronic address:
Switching the reaction routes in peroxymonosulfate (PMS)-based advanced oxidation processes have attracted much attention but remain challenging. Herein, a series of Co-N/C catalysts with different compositions and structures were prepared by using bimetallic zeolitic imidazolate frameworks based on ZIF-8 and ZIF-67 (xZn/Co-ZIFs). Results show that Co doping amount could mediate the transformation of the activation pathway of PMS over Co-N/C.
View Article and Find Full Text PDFChem Commun (Camb)
October 2023
Department of Chemistry and Bioscience, Aalborg University, DK-9220 Aalborg, Denmark.
The high-density amorphous phases (HDAs) of bimetallic zeolitic imidazolate frameworks (Zn/Co-ZIF-4) were prepared. The temperature dependence of the isobaric heat capacity () of ZIF-4 HDAs was measured to determine the glass transition temperature () of HDAs. The non-linearly decreases with the molar ratio , where is Co/(Co + Zn), indicating the presence of a mixed-metal node effect.
View Article and Find Full Text PDFChemphyschem
October 2023
School of Metallurgy and Environment, Central South University, Changsha, 410083, Hunan, P. R. China.
Single-atom M-N (M=Fe, Co, Ni) catalysts exhibit high activity for CO reduction reaction (CO RR). However, the CO RR mechanism and the origin of activity at the single-atom sites remain unclear, which hinders the development of single-atom M-N catalysts. Here, using density functional theory calculations, we reveal intermediates-induced CO RR activity at the single-atom M-N sites.
View Article and Find Full Text PDFPhys Chem Chem Phys
July 2023
Anhui Province Key Laboratory of Optoelectric Materials Science and Technology, Department of Physics, Anhui Normal University, Wuhu, Anhui 241000, China.
State-to-state rotational energy transfer in collisions of ground ro-vibrational state CO molecules with N molecules has been studied using the crossed molecular beam method under kinematically equivalent conditions used for CO + CO rotationally inelastic scattering described in a previously published report (Sun , , 2020, , 307-309). The collisionally excited CO molecule products are detected by the same (1 + 1' + 1'') VUV (Vacuum Ultra-Violet) resonance enhanced multiphoton ionization scheme coupled with velocity map ion imaging. We present differential cross sections and scattering angle resolved rotational angular momentum alignment moments extracted from experimentally measured CO + N scattering images and compare them with theoretical predictions from quasi-classical trajectories (QCT) on a newly calculated CO-N potential energy surface (PES).
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