Facile In Situ Synthesis of Supported Gold Catalysts on Ti3AlC2-Based Nanofibers for Selective Oxidation of Biomass-Derived HMF and Aromatic Alcohols

Abstract

Supported metal catalysts play a significant role in the selective organic synthesis and valorization of bio-derived platform molecules, and the development of catalyst preparation method is an important research topic. The facile in situ reduction synthesis strategy was investigated to prepare gold catalysts on Ti3AlC2-derived nanofibrous materials, using “as-produced H2” during hydrothermal synthesis as a reductive agent. The results of catalyst characterizations revealed that the metallic Au NPs (gold nanoparticles) were loaded with high efficiency. The new series of Aupre/Ti3AlxC2Ty catalysts as prepared by the in situ reduction method generally exhibited higher conversions in the selective oxidation of biomass-derived HMF (5-hydroxymethylfurfural) and aromatic alcohols, outperforming the traditional series of Audp/Ti3AlxC2Ty catalysts as made by the deposition–precipitation method. The HMF conversion was 96.9% over 2%Aupre/Ti3AlxC2Ty and was 76.9% over 2%Audp/Ti3AlxC2Ty. The HMFCA (5-hydroxymethyl-2-furan carboxylic acid) selectivity over these two catalysts was almost identical, whereas it was 96.3% over 1%Aupre/Ti3AlxC2Ty and 84.3% over 1%Audp/Ti3AlxC2Ty. The catalyst reusability tests proved that the typical catalyst Aupre/Ti3AlxC2Ty maintained reaction rates and product selectivity in at least three cycles, whereas the reusability of Audp/Ti3AlxC2Ty catalyst was relatively weaker in both reactions. Finally, the plausible catalytic mechanism was discussed according to peer studies and the research results.