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Understanding and tuning the crystal-facet-dependent catalytic properties of catalysts are of great importance for the selective oxidation of polyols. Herein, a series of α-Mn2O3 catalysts with various morphologies (octahedron, truncated octahedron, and cube) are successfully synthesized for the enhanced selective oxidation of glycerol to glycolic acid. Our results show that the different catalytic performances of Mn2O3 catalysts with various morphologies originated from the chemical nature of the (001) and (111) facets. Multicharacterizations and density functional theory calculations revealed that the surface oxygen vacancies on the (001) facets are well correlated with the catalytic activity, and the C–H bond in oxygen-containing intermediates could be easily activated on the surface oxygen vacancies of the (001) facets, thus improving the catalytic activity. Moreover, the main role of (111) facets is to prevent the over-oxidation of glycolic acid products, leading to the improvement of glycolic acid selectivity. Consequently, the Mn2O3-truncated octahedron catalyst with both (001) and (111) facets shows high catalytic activity (0.87 mmol/(h m2)) and glycolic acid selectivity (52.6%) simultaneously. We anticipate that this work could give some suggestions for the design of highly efficient inexpensive catalysts in the glycerol oxidation system.

Glycolic acid (GA) is a promising building block for synthesizing biodegradable materials, which could replace conventional coal-derived and petroleum-derived plastic materials. However, conventional coal-based GA routes are facing severe obstacles in nonrenewable energy consumptions and pollutant emissions. Biomass energy is regarded as a potential contributor to a greener and cleaner development. Herein, we develop and evaluate a novel ethylene glycol (EG) selective oxidation to GA process using renewable biomass energy, which aims to realize the sustainable and cost-effective production of GA based on the highly efficient bimetallic PtMn/MCM-41 nanocatalysts. Compared with other GA production processes, the bio-based EG selective oxidation to GA process has significantly boosted the techno-economic performance (increasing the energy efficiency by 19.7% and the net present value by 121%). Furthermore, the life cycle society−environment assessment also indicates that the performance of fossil energy demand (FED), greenhouse gas (GHG) emissions, and water resource consumption (WRC) in the EG selective oxidation to GA process is superior to that of other coal-based techniques (reducing FED, GHG, and WRC by 881.3, 32.7, and 47.8%, respectively). This study aims to give unambiguous and quantitative results for developing a sustainable and cost-effective bio-based GA production process and provide guidance for other engineering applications of biomass polyhydric alcohols.

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.

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