Oxygen Vacancies Enrichment in Citric Acid-Assisted Synthesis of Zirconia Supported Ni Catalyst for Highly Selective Hydrogenolysis of 5-Hydroxymethylfurfural.

2, 5-Dimethylfuran (DMF), which is a promising new-generation liquid biofuel, has attracted widespread attention owing to the sustainability of biomass-derived energy sources. In this study, a highly dispersed zirconia-supported nickel catalyst (CA-Ni/ZrO2) was prepared via citric acid-assisted wetness impregnation for the selective hydrogenolysis of 5-hydroxymethylfurfural (HMF) to produce DMF. The characterization results confirmed the presence of Zr3+ species in the mesoporous CA-Ni/ZrO2 catalyst and the formation of oxygen vacancies during its preparation, which led to the formation of a large number of catalytically active sites for the adsorption and activation of the C=O/C-O groups. Under appropriate reaction parameters, an excellent DMF selectivity of 99.1% and an HMF conversion of 98.4% were achieved. A suitable kinetic model revealed that DMF was preferentially formed via the 2,5-dihydroxymethylfuran intermediate route, although a 5-methylfurfural route was also observed. Additionally, the interaction between Ni and ZrO2 significantly affected the stability of the catalyst. This study will provide guidelines for optimizing the catalytic conversion of furan derivatives over heterogeneous catalysts.

Template-Oriented Polyaniline-Supported Palladium Nanoclusters for Reductive Homocoupling of Furfural Derivatives.

Developing well-defined structures and desired properties for porous organic polymer (POP) supported catalysts by controlling their composition, size, and morphology is of great significance. Herein, we report a preparation of polyaniline (PANI) supported Pd nanoparticles (NPs) with controllable structure and morphology. The protocol involves the introduction of MnO2 with different crystal structures (α, ß, γ, δ, ϵ) serving as both the reaction template and the oxidant. The different forms of MnO2 each convert aniline to a PANI that contains a unique regular distribution of benzene and quinone. This leads to the Pd/PANI catalysts with different charge transfer properties between Pd and PANI, as well as different dispersions of the metal NPs. In this case, the Pd/ϵ-PANI catalyst greatly improves the turnover frequency (TOF; to 88.3 h-1 ), in the reductive coupling of furfural derivatives to potential bio-based plasticizers. Systematic characterizations reveal the unique oxidation state of the support in the Pd/ϵ-PANI catalyst and coordination mode of Pd that drives the formation of highly dispersed Pd nanoclusters. Density functional theory (DFT) calculations show the more electron rich Pd/PANI catalyst has the lower energy barrier in the oxidative addition step, which favors the C-C coupling reaction.

Efficient synthesis of 5-ethoxymethylfurfural from biomass-derived 5-hydroxymethylfurfural over sulfonated organic polymer catalyst.

Herein, we investigated catalytic potential of a functionalized porous organic polymer bearing sulfonic acid groups (PDVTA-SO3H) to the etherification of 5-hydroxymethylfurfural (HMF) to 5-ethoxymethylfurfural (EMF) under solvent-free conditions. The PDVTA-SO3H material was synthesized via post-synthetic sulfonation of the porous co-polymer poly-divinylbenzene-co-triallylamine by chlorosulfonic acid. The physicochemical properties of the PDVTA-SO3H were characterized by FT-IR, SEM, TG-DTG, and N2 adsorption isotherm techniques. PDVTA-SO3H had high specific surface area (591 m2 g-1) and high density of -SO3H group (2.1 mmol g-1). The reaction conditions were optimized via Box-Behnken response surface methodology. Under the optimized conditions, the PDVTA-SO3H catalyst exhibited efficient catalytic activity with 99.8% HMF conversion and 87.5% EMF yield within 30 min at 110 °C. The used PDVTA-SO3H catalyst was readily recovered by filtration and remained active in recycle runs.