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Here, a series of nitrogen‐doped carbon (NC) supported transition metal oxide catalysts were prepared by pyrolysis of chitosan‐metal salt mixtures for the efficient synthesis 2,5‐diformylfuran (DFF) from 5‐hydroxymethylfurfural (HMF) and fructose. Among them, supported molybdenum‐based species on nitrogen‐doped carbon (Mo/NC) exhibited excellent activity and selectivity for selective oxidation of HMF to DFF. The presence of nitrogen species reduces the electron cloud density around the Mo species, thereby improving the catalytic activity. Moreover, the interaction between active MoO2 species on the catalyst surface and NC ensured the stability of the catalyst, resulting in no significant loss of activity after four catalytic cycles. 99.5 % and 55.1 % yields of DFF with full conversion were obtained from HMF and fructose respectively over Mo/NC‐chitosan‐600 in DMSO under ambient air. In order to enhance DFF yield from fructose, sulfonate groups were introduced into Mo/NC‐chitosan‐600 catalyst, leading to the highest DFF yield of 70.2 %. In addition, this catalyst also allowed 10.0%, 22.9% and 33.3% DFF yields from glucose, sucrose and inulin, respectively. [ABSTRACT FROM AUTHOR]

γ‐Valerolactone (GVL) is considered as a star biochemical which can be used as a green solvent, fuel additive and versatile organic intermediate. In this study, metal triflate (M(OTf)n) was utilized as the catalyst for one‐pot transformation of furfural (FF) to GVL in alcohol media under microwave irradiation. Alcohol plays multiple functions including solvent, hydrogen donor and alcoholysis reagent in this cascade reaction process. And process efficiency of GVL production from FF upgrading is strongly related to the effective charge density of selected catalyst and the reduction potential of selected alcohol. Complex (OTf)n‐M−O(H)R, presenting both Brønsted acid and Lewis acid, is the real catalytic active species in this cascade reaction process. Among various catalysts, Sc(OTf)3 exhibited the best catalytic activity for GVL production. Various reaction parameters including the Sc(OTf)3 amount, reaction temperature and time were optimized by the response surface methodology with the central composite design (RSM‐CCD). Up to 81.2 % GVL yield and 100 % FF conversion were achieved at 143.9 °C after 8.1 h in the presence of 0.16 mmol catalyst. This catalyst exhibits high reusability and can be regenerated by oxidative degradation of humins. In addition, a plausible cascade reaction network was proposed based on the distribution of product. [ABSTRACT FROM AUTHOR]

γ‐Valerolactone (GVL) is considered as a star biochemical which can be used as a green solvent, fuel additive and versatile organic intermediate. In this study, metal triflate (M(OTf)n) was utilized as the catalyst for one‐pot transformation of furfural (FF) to GVL in alcohol media under microwave irradiation. Alcohol plays multiple functions including solvent, hydrogen donor and alcoholysis reagent in this cascade reaction process. And process efficiency of GVL production from FF upgrading is strongly related to the effective charge density of selected catalyst and the reduction potential of selected alcohol. Complex (OTf)n‐M−O(H)R, presenting both Brønsted acid and Lewis acid, is the real catalytic active species in this cascade reaction process. Among various catalysts, Sc(OTf)3 exhibited the best catalytic activity for GVL production. Various reaction parameters including the Sc(OTf)3 amount, reaction temperature and time were optimized by the response surface methodology with the central composite design (RSM‐CCD). Up to 81.2 % GVL yield and 100 % FF conversion were achieved at 143.9 °C after 8.1 h in the presence of 0.16 mmol catalyst. This catalyst exhibits high reusability and can be regenerated by oxidative degradation of humins. In addition, a plausible cascade reaction network was proposed based on the distribution of product. [ABSTRACT FROM AUTHOR]

The tuning of catalyst structures is a significant strategy to produce highly active catalysts. Five primary methods were used herein to prepare NiCo composite catalysts, which were named NiCo-SG (sol–gel method), NiCo-PC (precipitation method), NiCo-WT (hydrothermal method), NiCo-ST (soft template method), and NiCo-HT (hard template method). Characterization indicated that there were different surface and bulk properties for these catalysts. Activity evaluation was subsequently conducted using CO2 methanation as a probe reaction. The results showed that the activity of CO2 methanation on the catalyst was positively correlated with the absorption of CO2, and with high CO2 methanation for NiCo-ST and NiCo-HT: the highest CH4 formation rates were 4.55 and 4.56 × 10−5 mol gcat−1 s−1, respectively. This was attributed to the Ni–Co alloy and spherical clusters of the former and the large specific surface area and developed bimodal mesoporous structure of the latter. [ABSTRACT FROM AUTHOR]