Chenggong Sun, University of Nottingham, was awarded funding in our Scientific Council Collaboration Fund 2019 to look at “CO2 utilisation for photo-catalytic mass production of glycerol carbonate from crude glycerol as a versatile chemical building block in chemical industry”.
Glycerol, also known as glycerine, is a major primary byproduct of biofuel production, with the rapidly expanding global biodiesel production alone generating over five million tons per annum at present. As a result, there has been a great surge of interest in using glycerol as an abundant renewable feedstock to produce more advanced biofuels and biochemicals, whilst improving the economic performance and resource efficiency of biofuel production. Here, we describe, for the first time, the selective catalytic conversion of glycerol to 2,5-hexanedione (2,5-HD) and other more advanced C6-C12 cycloalkanes and/or polyketones by making use of water hydrogen under relatively mild conditions. 2,5-HD is recognised as being a vital gateway chemical for the synthesis of pesticides, resin materials and high-density aviation biofuels.
A type of copper-carbon nanocomposite catalyst was prepared on a small lab scale by using a metal–organic framework (MOF) precursor through an integrated pyrolysis and activation methodology. The catalyst was found to exhibit rarely seen catalytic activity for the desirable selective conversion of glycerol to 2,5-HD and other more advanced C8-C12 cyclo-alkanes/oxygenates, and no externally supplied hydrogen was needed as the hydrogen required can be generated in situ from simultaneous aqueous glycerol reforming reactions, which were also catalysed by this catalyst. The selectivity could reach 43.4% for the formation of 2,5-hexanedione and over 70% for total C8-C12 cyclo-alkanes/poly-oxygenates under the experimental conditions examined. It is believed that the catalytic conversion can potentially be tuned to facilitate the production of either 2,5-HD or more advanced polycyclic alkanes and/or ketones as the major products. Characterizations show that the remarkable catalytic capability of the MOF-derived catalyst arose not only from the highly dispersion of copper in the carbon substrate but also from the unique chemical states of the distributed copper species, a novel physicochemical feature that cannot be achieved with conventional catalyst preparation methodologies. Although the research is still at its preliminary stage, the results augur very well for the production of high-density aviation fuels from glycerol refinery.
As a part of this Collaboration award, we were delighted to collaborate with Prof Xianfeng Fan at the University of Edinburgh.