Deuterium-Labeling Study of the Hydrogenation of 2-Methylfuran and 2,5-Dimethylfuran over Carbon-Supported Noble Metal Catalysts

Hydrodeoxygenation of 2,5-dimethyltetrahydrofuran over bifunctional Pt-Cs2.5H0.5PW12O40 catalyst in the gas phase: enhancing effect of gold

2,5-Dimethyltetrahydrofuran (DMTHF) is deoxygenated to n-hexane with >99% selectivity at mild conditions (90 °C, 1 bar H₂ pressure, fixed-bed reactor) in the presence of the bifunctional metal-acid catalyst Pt–CsPW comprising Pt and Cs_2.5H_0.5PW₁₂O₄₀ (CsPW), an acidic Cs salt of Keggin-type heteropoly acid H₃PW₁₂O₄₀. Addition of gold to the Pt–CsPW catalyst increases the turnover rate at Pt sites more than twofold, whereas the Au alone without Pt is not active. The enhancement of catalyst activity is attributed to PtAu alloying, which is supported by STEM-EDX and XRD analysis.

Addition of gold to the Pt–CsPW catalyst has an enhancing effect on the HDO of DMTHF, with a twofold increase of turnover rate at Pt sites.

Facile gas-phase hydrodeoxygenation of 2,5-dimethylfuran over bifunctional metal-acid catalyst Pt–Cs2.5H0.5PW12O40

2,5-Dimethylfuran is deoxygenated to n-hexane with 100% yield on a bifunctional Pt/C–Cs_2.5H_0.5PW₁₂O₄₀ catalyst under very mild conditions (90 °C, 1 bar H₂) in a one-step gas-phase process.

Turnover Rate of Metal-Catalyzed Hydroconversion of 2,5-Dimethylfuran: Gas-Phase Versus Liquid-Phase

Hydroconversion (hydrogenation and hydrogenolysis) of biomass-derived furanic compounds giving furan ring-hydrogenation and ring-cleavage products attracts interest for sustainable production of chemicals and fuels. Here, the hydroconversion of 2,5-dimethylfuran (DMF), chosen as a model furanic compound, was investigated at a gas-solid interface over carbon-supported Pt, Pd, Rh and Ru metal catalysts in a fixed-bed reactor at 70–90 °C and ambient pressure. Pt/C was mainly active in ring cleavage of DMF to produce 2-hexanone as the primary product, followed by its hydrogenation to 2-hexanol and hexane. In contrast, Pd/C, Rh/C and Ru/C selectively hydrogenated the furan ring to 2,5-dimethyltetrahydrofuran (DMTHF). The turnover frequency (TOF) of metal sites in the gas-phase DMF hydroconversion was determined from zero-order kinetics in the absence of diffusion limitations. The TOF values decreased in the sequence Pt > Rh > Pd >> Ru, similar to the liquid-phase reaction. The TOF values for the gas-phase reaction were found to be one order of magnitude greater than those for the liquid-phase reaction. This indicates that the gas-phase process is potentially more efficient than the liquid-phase process. TOF values for hydroconversion of ring-saturated furan derivatives, tetrahydrofuran and DMTHF, on Pt/C, were much lower than those for DMF.

How Catalysts and Experimental Conditions Determine the Selective Hydroconversion of Furfural and 5-Hydroxymethylfurfural

Furfural and 5-hydroxymethylfurfural stand out as bridges connecting biomass raw materials to the biorefinery industry. Their reductive transformations by hydroconversion are key routes toward a wide variety of chemicals and biofuels, and heterogeneous catalysis plays a central role in these reactions. The catalyst efficiency highly depends on the nature of metals, supports, and additives, on the catalyst preparation procedure, and obviously on reaction conditions to which catalyst and reactants are exposed: solvent, pressure, and temperature. The present review focuses on the roles played by the catalyst at the molecular level in the hydroconversion of furfural and 5-hydroxymethylfurfural in the gas or liquid phases, including catalytic hydrogen transfer routes and electro/photoreduction, into oxygenates or hydrocarbons (e.g., furfuryl alcohol, 2,5-bis(hydroxymethyl)furan, cyclopentanone, 1,5-pentanediol, 2-methylfuran, 2,5-dimethylfuran, furan, furfuryl ethers, etc.). The mechanism of adsorption of the reactant and the mechanism of the reaction of hydroconversion are correlated to the specificities of each active metal, both noble (Pt, Pd, Ru, Au, Rh, and Ir) and non-noble (Ni, Cu, Co, Mo, and Fe), with an emphasis on the role of the support and of additives on catalytic performances (conversion, yield, and stability). The reusability of catalytic systems (deactivation mechanism, protection, and regeneration methods) is also discussed.

C-H Functionalisation for Hydrogen Isotope Exchange

The various applications of hydrogen isotopes (deuterium, D, and tritium, T) in the physical and life sciences demand a range of methods for their installation in an array of molecular architectures. In this Review, we describe recent advances in synthetic C-H functionalisation for hydrogen isotope exchange.

Burgess iridium(I)-catalyst for selective hydrogen isotope exchange

We have evaluated the commercially available Burgess catalyst in hydrogen isotope exchange reactions with several substrates bearing different directing group functionalities and have obtained moderate to high (50%-97%D) deuterium incorporations. The broad applicability in hydrogen isotope exchange reactions makes the Burgess catalyst a possible alternative compared to other commercially available iridium(I)-catalysts.

One-pot production of 2,5-dimethylfuran from fructose over Ru/C and a Lewis–Brønsted acid mixture in N,N-dimethylformamide

A one-pot process for the production of 2,5-dimethylfuran from fructose by using Ru/C and a Lewis–Brønsted acid mixture as catalysts.