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Please use this identifier to cite or link to this item: http://hdl.handle.net/123456789/12898

Title: Hydrogenation of carbon dioxide to formate by a-diimine RuII, RhIII, IrIII complexes as catalyst precursors
Authors: Makuve, Nyasha
Mehlana, Gift
Tia, Richard
Darkwa, James
Makhubela, Banothile C.E.
Keywords: CO2 hydrogenation
Homogeneous catalysis
a-diimine complexes
Mechanistic studies
DFT calculations
Issue Date: 15-Aug-2019
Publisher: Elsevier B.V.
Abstract: The conversion of CO2 into valuable chemicals has been of major interest because it is cheap and readily available. The concept of reducing CO2 pollution via its utilization into valuable products has inspired us to synthesise novel 4,4'-((1Z)-butane-2,3-diylidenebis(azanylylidene))dibenzoic acid (L) metal complexes {[(L)RuII] (C1), [(L)RhIII] (C2), [(L]IrIII (C3)} complexes for catalytic hydrogenation of CO2. The adiimine metal complexes (C1eC3) were characterised using several analytical techniques, including: NMR spectroscopy and single crystal X-ray crystallography. In a mixture of THF/H2O and a base, all three catalyst precursors were able to hydrogenate CO2 cleanly to formate as a product. However, the best combination of catalyst precursor and a base was C1 and DBU that selectively produced formate at a moderate temperature of 120 C and at 60 bar. The best productivity under these conditions is TOF of 35 h1 within 2 h and a TON of 322. This work is significant because it provides a one-step synthesis for formate from CO2 using a-diimine-based complexes which can be synthesised in a one-step reaction. The density functional theory calculations on C1 supports that RueH is the active species in the process of CO2 hydrogenation to formate with the insertion of the CO2 to RueH being the rate determining step.
Description: An article published by Elsevier B.V and also available at https://doi.org/10.1016/j.jorganchem.2019.120892
URI: http://hdl.handle.net/123456789/12898
Appears in Collections:College of Science

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