Postgraduate Seminar Presentation : Role of the strong Lewis base sites on glucose hydrogenolysis

Speaker Parviz Yazdani (Supervisor: A/P Sibudjing Kawi)

Host Department of Chemical and Biomolecular Engineering

Date/Time 18 May - 18 May, 4.00pm

Venue E5-02-32 , Faculty of Engineering, National University of Singapore

Synopsis

This work reports the individual role of strong Lewis base sites on catalytic conversion of glucose hydrogenolysis to acetol/lactic acid, including glucose isomerisation to fructose and pyruvaldehyde rearrangement/hydrogenation to acetol/lactic acid. La2O3, Nd2O3, Sm2O3, and Pr6O11 were selected as representative oxides consisting of different base sites. The basicity of these lanthanide oxides was characterised by CO2-TPD and DRIFT spectroscopy. It was found that lanthanide cation-oxygen pairs, Brønsted OH group coordinated with one Lanthanide cation, and lanthanide cation near lanthanide cation-oxygen pairs are the dominant base sites as compared to the other base sites on La2O3, Nd2O3, Sm2O3 and Pr6O11. In addition, the relative concentration of the base sites is different over the examined lanthanide oxides. These unique properties of lanthanide oxides are used to understand the individual role of base sites on the reactions mentioned above. Then, the catalytic results were correlated with the base properties of these lanthanide oxides. Based on this correlation, the base site requirements for each reaction were identified. In this regard, Brønsted OH group coordinated with one anthanide cation over Nd2O3 was found to be the suitable base site for glucose isomerisation. On the other hand, lactic acid is produced as the main product in glucose hydrogenolysis over lanthanide cation near lanthanide-oxygen pairs on Pr6O11. Finally, lanthanide-oxygen pairs over La2O3 are suitable base sites for retro-aldol condensation of fructose to C3 chemicals.

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