Selective photocatalytic oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxaldehyde by polymeric carbon nitride-hydrogen peroxide adduct

Abstract

Polymeric carbon nitride-hydrogen peroxide adduct (PCN-H2O2) has been prepared, thoroughly characterised and its application for selective photocatalytic conversion of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxaldehyde (FDC) in aqueous suspension has been studied. The PCN-H2O2 adduct is stable in aqueous suspension under UV and solar irradiation up to 100 °C. It is also stable up to 200 °C if heated in air, while at temperatures close to 300 °C its decomposition takes place. Based on the obtained characterisation data it has been proposed that H2O2 attaches to the non-polymerised carbon nitride species and to the heptazine nitrogen atoms, thus producing strong hydrogen bonding within the PCN-H2O2 adduct. The blockage of the surface amino-groups in PCN-H2O2 by H2O2 hinders the interaction of HMF with these sites, which are responsible for unselective substrate conversion. PCN-H2O2 possesses a superior selectivity in natural solar light assisted oxidation of HMF to FDC reaching 80% with respect to its thermally etched PCN counterpart, which gives rise to a 40-50% selectivity. We believe that the exceptional performance of the applied photocatalyst in the selective photocatalytic conversion of HMF to a high added value FDC in a green solvent under natural illumination makes a significant contribution to the development of environmentally friendly technologies for biomass valorisation.

Photoactivity of shape-controlled TiO2 in gas-solid regime under solar irradiation

“…Consequently, a comparison between the results obtained in different runs is possible only if the overall photon energy impinging on the reactor during each photocatalytic run is taken into account. This latter was calculated as already detailed [28,29], by measuring the irradiance during each experimental run.…”

Selective Oxidation of HMF via Catalytic and Photocatalytic Processes Using Metal-Supported Catalysts

“…Currently, there is a growing interest in the photocatalytic synthesis of organics, mainly the oxidation of hydroxyl functional groups to aldehydes, because it enables preventing the use of strong chemical oxidants, toxic solvents and by-products, high temperatures, and pressures [ 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 ].…”

Graphitic Carbon Nitride‐Based Materials as Catalysts for the Upgrading of Lignocellulosic Biomass‐Derived Molecules

“…Later, Krivtsov and co-workers [37] described the preparation of a modified g-C 3 N 4 catalyst via thermal exfoliation followed by the functionalization with hydrogen peroxide, thus creating a H 2 O 2 -g-C 3 N 4 adduct. The authors proposed the formation of midgap states in the electronic structure for the H 2 O 2 -g-C 3 N 4 catalyst, which led to a higher HMF conversion and DFF selectivity when compared to the pure g-C 3 N 4 (20 % and 71 % vs 20 % and 40 %, respectively).…”