Hybrid Organic–Inorganic Anatase as a Bifunctional Catalyst for Enhanced Production of 5‐Hydroxymethylfurfural from Glucose in Water

Abstract

Hybrid organic-inorganic anatase (hybrid-TiO ) is prepared by a facile hydrothermal synthesis method employing citric acid. The synthetic approach results in a high surface-area nanocrystalline anatase polymorph of TiO . The uncalcined hybrid-TiO is directly studied as a catalyst for the conversion of glucose into 5-hydroxymethylfurfural (HMF). In the presence of the hybrid-TiO , HMF yields up to 45 % at glucose conversions up to 75 % were achieved in water at 130 °C in a monophasic batch reactor. As identified by Ti K-edge XANES, hybrid-TiO contains a large fraction of fivefold coordinatively unsaturated Ti sites, which act as the Lewis acid catalyst for the conversion of glucose into fructose. As citric acid is anchored in the structure of hybrid-TiO , carboxylate groups seem to catalyze the sequential conversion of fructose into HMF. The fate of citric acid bound to anatase and the Ti Lewis acid sites throughout recycling experiments is also investigated. In a broader context, this contribution outlines the importance of hydrothermal synthesis for the creation of water-resistant Lewis acid sites for the conversion of sugars. Importantly, the use of the hybrid-TiO with no calcination step contributes to dramatically decreasing the energy consumption in the catalyst preparation.

Production of 5-Hydroxymethylfurfural from Glucose in Water by Using Transition Metal-Oxide Nanosheet Aggregates

“…The present study demonstrated that HNbWO 6 nanosheet aggregates exhibited the highest HMF yield with the highest selectivity under the lowest reaction temperature among oxides without any modifications (entries 1,2). Recent studies showed that a hybrid TiO 2 (entry 13) [34] and mesoporous metal phosphates (entries 15,16) [35,36] gave higher HMF yield as well as H 3 PO 4 -treated niobic acid (entry 14) [30]. This suggests that some modification of oxide catalysts including treatment with phosphoric acid will improve the activity.…”

Tuning Brønsted and Lewis acidity on phosphated titanium dioxides for efficient conversion of glucose to 5-hydroxymethylfurfural

“…The reaction temperature basically ranged in 120-200 C, althought the temperature below 140 C typically gave relatively low HMF yield. 26,38,39 The HMF yield above 50% were obtained from catalysts functionalized by acids including SO 3 H-ZSM-5, 69 SnP, 70 PO 4 /NU(half), 15 and Fe/AR. 67 The SO 3 H-SPPS catalyst exhibited very high HMF yield of 87% in an ionic liquid [EMIM]Cl as a reaction medium, yet the cost effectiveness of ionic liquid remains controversial in an industrialization aspect.…”

“…38 Similarly, hybrid organic-inorganic anatase (hybrid-TiO 2 ), which is synthesized by a hydrothermal synthesis technique using citric acid (CA), displays the HMF yield of 45%. 39 Such low to moderate HMF yields are likely due to the instability of HMF in heated water leading to various side products. 34 Here, we report a catalytic system comprising a phosphate-modied TiO 2 catalyst (P-TiO 2 ) for high yield production of HMF from glucose.…”

Inhibitory effect of oxygenated heterocyclic compounds in mesoporous catalytic materials: A pulsed-field gradient NMR diffusion study

“…The choice of this system is threefold: i) Mixtures of cyclohexane/1,4-dioxane are representative of typical hydrocarbon and oxygenated heterocyclic compounds used as solvent media in liquid-phase catalysis. In addition, TiO2 is used in catalytic reactions as support [7,8] and catalysts [9,10]. The role of such materials in affecting adsorption and catalytic performances is often considered to be a key step [11,12].…”