Synthesis of high-value organic acids from sugars promoted by hydrothermally loaded Cu oxide species on magnesia

• Efficient catalytic conversion of biomass-derived sugars to organic acids.
• High yields of lactic acid (70%) and formic acid (65%) at 393 K.
• Hydrothermal preparation of CTAB-capped Cu/MgO as a reusable heterogeneous catalyst.
• Characterization of active Cu species.

Design of a suitable catalyst for the conversion of inedible-biomass, a renewable resource, into high-value chemicals is an immense and important area of research in an era of energy crisis. This paper demonstrates batch conversion of sugars into lactic acid (LA) and formic acid (FA) employing a supported copper catalyst. A magnesia-supported copper catalyst was synthesized by a hydrothermal methodology using CTAB as the capping agent (denoted as CuCTAB/MgO). We found that the CuCTAB/MgO not only dramatically boosted the yields of LA and FA from sugars but also decreased the energy demand of the process by decreasing the reaction temperature from 523 K to 393 K. The high yields of LA (70%) in the presence of NaOH and of FA (65%) in the presence of H2O2 were achieved from glucose at 393 K in water using a CuCTAB/MgO catalyst, which could be recycled without any significant loss of activity. The copper catalyst was also found to exhibit excellent activity for the transformation of other sugars. The catalyst was characterized using PXRD, H2-TPR, N2 adsorption–desorption, and other analytical techniques to investigate the active Cu species and propose a plausible mechanistic pathway to LA.

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