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• Heterogeneous Co 0.8 Ni 0.2 -CNTs was effective for oxidative esterification of furfural. • >99% yield of methyl furoate was obtained with great formation rate of 1980 μmol·g cat −1·h−1. • The cooperation of Co-N x and Ni-N x sites is responsible for oxidative esterification. • The Ni-N x sites contributed to the adsorption of the aldehyde group in furfural. • Doping of Ni boosts the basicity of the catalyst and accelerates hydrogen abstraction. Developing active and affordable catalysts for the transformation of biomass platform into value-added chemicals have drawn tremendous attention. Herein, we have successfully prepared a CoNi bimetallic nitrogen-doped carbon nanotubes (CNTs) catalyst, manifesting outstanding catalytic performance for furfural oxidative esterification under base-free conditions (methyl furoate yield >99%), and great recyclability (5th recycle). Importantly, an impressive methyl furoate formation rate of around 1980 μmol methyl furoate ·g cat −1·h−1 was achieved, to the best of our knowledge, the result represents one of the highest methyl furoate formation rates. The results revealed that the doping of Ni into the Co x Ni y -CNTs catalyst brings about more active sites. Fourier transforms infrared spectrometer results suggest that the Ni-N x sites are responsible for the adsorption of the substrate with tilted or vertical adsorption. Furthermore, the introduction of Ni facilitates the improvement of basicity, which in turn promotes the β-hydride elimination. All of these active sites boost the overall activity of the catalyst for the oxidative esterification of furfural. Synopsis : The fabrication of N-doped carbon nanotubes supported CoNi bimetallic catalyst with enhanced O 2 activation ability and hydrogen abstraction ability presents excellent activity for base-free oxidative esterification of furfural. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Non-noble Ni 0.5 Co 0.5 Al catalyst was effective for reductive esterification of FA. • Complete conversion of FA with MeTHFC yield up to 99% was achieved. • High activity originates from the synergistic of metallic sites and acid sites in Ni 0.5 Co 0.5 Al. • Metallic sites were mainly responsible for the adsorption and dissociation of H 2. • The acid sites of Ni 0.5 Co 0.5 Al boost the esterification of FA. Reduction of high oxidation level furancarboxylic acid (FA) with the retention of the carboxyl group is particularly important for the utilization, however, it has been rarely explored over non-precious catalysts and is challenging. Here, we demonstrate an excellent noble-metal-free trimetallic NiCoAl catalyst for the reductive esterification of FA to methyl 2-tetrahydrofuroate (MeTHFC), which delivers the complete conversion of FA and MeTHFC yield of up to 99%. More importantly, Ni 0.5 Co 0.5 Al could offer Y MeTHFC > 90% over five reusability cycles. Detailed investigations suggest that the high activity originates from the synergistic of Ni-Co alloys sites and acid sites in Ni 0.5 Co 0.5 Al. The Ni-Co alloy sites were mainly responsible for the adsorption and dissociation of H 2 , which in turn improved hydrogenation activity, while the acid sites facilitated the esterification of FA and the adsorption and further activation of the furan ring. This work provides an eco-friendly noble-metal-free catalyst to enrich the strategies for the reductive esterification process. [ABSTRACT FROM AUTHOR]

• Heterogeneous MoCuO x catalyst was effective for selective oxidation of FMF to FDCA. • A 100% FDCA yield was achieved with NaClO oxidant in only 30 min at 40 °C over MoCuO x. • More oxygen mobility and lattice oxygen ratio endowed excellent reactivity of MoCuO x. • A tilted or vertical configuration of FMF guaranteed high FDCA selectivity. • The Cu and Mo species in MoCuO x through redox cycle boosted the catalytic activity. Generally, 5-hydroxymethylfurfural (HMF) is used as feedstock to produce 2,5-furandicarboxylic acid (FDCA). Whereas, its poor stability in alkaline environment results in low yield of FDCA. By contrast, 5-[(formyloxy)methyl]furfural (FMF), a novel platform compound derived from HMF, with higher thermal and alkaline stability than HMF, is more promising to replace HMF as substrate for the production of FDCA. In this study, FMF was successfully converted into FDCA over MoCuO x by using NaClO as oxidant, undergoing 2,5-diformylfuran (DFF) and 5-hydroxymethylfuran-2-carboxylic acid (HMFCA) as intermediates. Under optimization condition (30 min, 40 °C), 100% yield of FDCA was obtained. Furthermore, it was also demonstrated that the yield of FDCA up to 90% was gained in 5 wt % FMF concentration. Higher oxygen species mobility and lattice oxygen ratio endowed MoCuO x excellent catalytic activity. The synergy of Mo and Cu species in MoCuO x ensured an efficient conversion of HMF to FDCA through synergistic redox couple of Mo6+/Mo5+ and Cu2+/Cu+. A novel protocol for the transformation of FMF into FDCA with NaClO as oxidant over the bimetal MoCuO x catalyst. [Display omitted] [ABSTRACT FROM AUTHOR]