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Oxidation of renewable polyol/sugar into formic acid using molecular O2 over heterogeneous catalysts is still challenging due to the insufficient activation of both O2 and organic substrates on coordination-saturated metal oxides. In this study, we develop a defective MnO2 catalyst through a coordination number reduction strategy to enhance the aerobic oxidation of various polyols/sugars to formic acid. Compared to common MnO2, the tri-coordinated Mn in the defective MnO2 catalyst displays the electronic reconstruction of surface oxygen charge state and rich surface oxygen vacancies. These oxygen vacancies create more Mnδ+ Lewis acid site together with nearby oxygen as Lewis base sites. This combined structure behaves much like Frustrated Lewis pairs, serving to facilitate the activation of O2, as well as C–C and C–H bonds. As a result, the defective MnO2 catalyst shows high catalytic activity (turnover frequency: 113.5 h−1) and formic acid yield (>80%) comparable to noble metal catalysts for glycerol oxidation. The catalytic system is further extended to the oxidation of other polyols/sugars to formic acid with excellent catalytic performance. This work develops defective MnO2 catalysts with Frustrated Lewis Pairs through a coordination number reduction strategy to enhance the aerobic oxidation of various polyols/sugars to formic acid. [ABSTRACT FROM AUTHOR]

Achieving efficient catalytic conversion over a heterogeneous catalyst with excellent resistance against leaching is still a grand challenge for sustainable chemical synthesis in aqueous solution. Herein, we devised a single‐atom Pt1/hydroxyapatite (HAP) catalyst via a simple hydrothermal strategy. Gratifyingly, this robust Pt1/HAP catalyst exhibits remarkable catalytic selectivity and catalyst stability for the selective oxidation of C2–C4 polyols to corresponding primary hydroxy acids. It is found that the Pt−(O−P) linkages with strong electron‐withdrawing function of PO43− (Pt1−OPO43− pair active site) not only realize the activation of the C−H bond, but also destabilize the transition state from adsorbed hydroxy acids toward the C−C cleavage, resulting in the sharply increased selectivity of hydroxy acids. Moreover, the strong PO43−‐coordination effect provides electrostatic stabilization for single‐atom Pt, ensuring the highly efficient catalysis of Pt1/HAP for over 160 hours with superior leaching resistance. [ABSTRACT FROM AUTHOR]

Catalytic transfer hydrogenolysis, using liquid H‐donors in the absence of pressurized H2 under mild temperatures, is regarded as the most important technology to substitute traditional hydrogenation processes in industry. Despite decade development with several breakthroughs in catalyst design, the reaction mechanism involved in H2 generation and subsequent hydrogenolysis reactions is still under debate. In this review, transfer hydrogenolysis of glycerol, as a representative example, on metallic catalysts is revised critically with respect to surface reaction mechanism and catalyst design. The detailed reaction pathways for propanol, methanol, formic acid and ethanol for H2 generation have been discussed systematically. In particular, reaction mechanism for catalytic C−H cleavage, H spillover/transfer and C−O cleavage reaction steps will be critically revised with experimental and theoretical results in literature. Insights into reaction pathways, mechanism and H2 transfer efficiency and structure‐performance relation for Pd, Cu and Ni catalysts will be provided for future development of catalyst manufacture and process development. The outcome of this work is useful for successful implementation of bio‐refinery. [ABSTRACT FROM AUTHOR]

[Display omitted] • The coupling reaction of glycerol and CO 2 was successfully realized via heterogeneous catalyst. • Cubic MgO displays more low-coordinated O2– originated from the unique atomic arrangement of (1 1 1) facet. • More low-coordinated O2– leads to abundant strongly basic sites and surface oxygen vacancies. • The reaction mechanism of MgO-C on the coupling reaction was clarified. Developing efficient halogen-free catalysts is still a significant challenge for adsorption and activation of CO 2 and further preparing glycerol carbonate. Herein, we successfully developed heterogeneous MgO catalyst via morphology-oriented regulation to catalyze the coupling reaction of glycerol and CO 2. Specifically, cubic MgO displays more low-coordinated O2– originated from the unique atomic arrangement of (1 1 1) facet, resulting in abundant strong basic sites and surface oxygen vacancies. These strong basic sites promote the adsorption of CO 2 to form thermodynamically stable monodentate carbonates near the oxygen vacancies. In addition, nearby surface oxygen vacancies could further enhance the transfer of electrons into the anti-bonding orbitals of CO 2 molecules. The synergistic catalytic effect between the strong basic sites and the surface oxygen vacancies significantly facilitates the cycloaddition reaction (the most critical step in the coupling reaction). Therefore, under the optimal reaction conditions (140 °C, 2 MPa CO 2 , and 4 h), the MgO-C catalyst showed 83 % glycerol conversion and 44 % glycerol carbonate selectivity. [ABSTRACT FROM AUTHOR]