Synergistic Effects of Bimetallic PtPd/TiO₂ Nanocatalysts in Oxidation of Glucose to Glucaric Acid: Structure Dependent Activity and Selectivity

Abstract

Direct oxidation of glucose with enhanced selectivity to glucaric acid with tartronic and oxalic acids as coproducts is reported using bimetallic PtPd/TiO 2 catalysts under mild conditions. Bimetallic PtPd catalysts display significantly enhanced catalytic activity (turnover frequency (TOF) 2404 h −1 ) and improved selectivity to glucaric acid (S 44%) in glucose oxidation compared to monometallic catalysts (TOF 248 h −1 , S 4%). Oxidation of glucose follows a consecutive reaction with gluconic acid as an intermediate with inhibition of the second step (to glucaric acid and C−C cleavage reactions) by the presence of glucose. Surface characterization using TEM, SEM, chemisorption, UV−vis spectroscopy, and XRD distinguished the particle morphologies and provided insights into structure−activity relations. A reaction pathway for glucose oxidation is proposed based on the product distribution. These results provide new insights into the design of bimetallic catalysts for the oxidation of glucose to glucaric acid.

How to Synthesise High Purity, Crystalline d‐Glucaric Acid Selectively

“…Recently companies such as Rennovia Inc. have commercialised catalytic processes for the preparation of glucaric acid from glucose, eschewing the nitric acid oxidant in favour of a platinum‐catalysed aerobic oxidation cycle , , . This is in line with a recent trend towards catalytic oxidation of glucose to glucaric acid . However despite this, K and Ca glucarate salts remain the commercially available forms of the acid.…”

Nanostructured Metal Catalysts for Selective Hydrogenation and Oxidation of Cellulosic Biomass to Chemicals

“…Six typical examples of such catalysts used in selective conversion of biomass to value‐added chemicals are illustrated in Figure . Figure (a) shows that PtPd alloy catalysts exhibit unusual activity for not only primary oxidation of glucose to gluconic acid, but also, more importantly, further (secondary) oxidation of gluconic acid to glucaric acid, which is difficult to achieve with conventional catalysts . Figure (b) illustrates shape (facet) selective catalysis of Cu 2 O nanocatalysts for glycerol dehydrogenation and reforming reactions .…”

“…Several Au‐ and Pt‐based catalysts have been shown to have promising performances in catalytic oxidation of glucose to glucaric acid . Boussie and co‐workers reported various metal catalysts for selective glucose oxidation to glucaric acid.…”

“…This is because of the enhanced degradation reactions of glucose over active PtCu catalysts by C−C cleavage reactions. To solve this issue, in a parallel study, we proposed alloy PtPd catalysts and confirmed that bimetallic catalysts exhibit synergistic performances in glucose oxidation (entry#1 in Table ) . Interestingly, there exists a glucose inhibition effect during oxidation reactions.…”

Oxidation of d‐Glucose to Glucaric Acid Using Au/C Catalysts

“…stated that the use of a commercial Pt/C catalyst enabled the oxidation of glucose and gluconic acid (GO), the main intermediate of glucose oxidation, at a neutral pH and mild conditions, with a glucose/Pt molar ratio of 54, and an optimised GA yield of 74 % . Chaudhari and co‐workers described the catalytic performance of supported PtPd and PtCu nanoparticle (NP) alloys for glucose oxidation with O 2 ,. For example, PtPd–TiO 2 catalysts showed a significantly enhanced catalytic activity and improved selectivity to GA (44 %) in the oxidation of aqueous glucose solution, compared to monometallic catalysts.…”