Aqueous phase oxidation of cellulosic and sugar derivatives is crucial for sustainable production of value-added carboxylic acids and derivatives. Tartaric acid (TA), a high value-added C4 dicarboxylic acid, has been widely used for additives in food, dye and pharmaceutical industries. Traditionally, chemical synthesis of TA is based on oxidation of maleic anhydride, generating amounts of toxic by-products. Up to date, there has been no detailed study on catalytic synthesis of TA from biomass using heterogeneous catalysts. In this work, we have proposed one-pot aqueous phase glucose oxidation to TA (yield: 50%) using AuPt/TiO2 catalysts at 110 oC and 2 MPa O2. Reaction pathway (Fig 1) of glucose oxidation was proposed to understand possible mechanism for TA formation. According to the preliminary studies, we conducted further structure-sensitivity analysis for oxidation of glucose and gluconic acid to TA, understanding possible reaction mechanism. Experimental studies have shown that the activation of C-H and C=O bonds tends to follow the σ-σ and π-π bond mechanisms on the catalyst surface. Structural characterization and DFT calculations showed that the lattice mismatch between fcc Pt and bcc Au induces the formation of twin boundaries in nanoclusters, result in Jahn-Teller distortion to reconfigure the electric field. As seen in Fig 2, such structural and electronic reconfiguration contributes to enhanced σ-activation of C-H bond competing with π-π electronic sharing of C=O bond. As a result, both C-H (oxidation) and C-C (decarboxylation) cleavage reactions synergistically occur on the surface of AuPt/TiO2 catalysts.

Synergistic AuPt/TiO2 catalyst for synthesis of cellulose-derived tartaric acid using molecular O2

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.