Metal–organic-framework-based catalysts for hydrogenation reactions

Metal-organic-framework （MOF）-based materials with novel physicochemical properties have emerged as promising catalysts for various hydrogenation reactions. In addition to metal clusters and multifunctional organic ligands, MOF-based catalysts can incorporate other functional species, and thus provide various active sites for hydrogenation processes. The structural properties of the catalysts play significant roles in enhancing the interactions among the reactants, products, and catalytic sites, which can be rationally designed. Because of the synergistic effects between the ac-tive sites and the structural properties, MOF-based catalysts can achieve higher activities and selec- tivities in hydrogenation reactions than can be obtained using traditional heterogeneous catalysts. This review provides an overview of recent developments in MOF-based catalysts in the hydro-genation of alkenes, alkynes, nitroarenes, cinnamaldehyde, furfural, benzene, and other compounds. Strategies for improving the catalytic performances of MOF-based catalysts are discussed as well as the different active sites and structural properties of the catalysts.

Structure-induced hollow Co3O4 nanoparticles with rich oxygen vacancies for efficient CO oxidation

Co3O4 has been considered as one kind of promising catalysts for the oxidation of CO. According to the Mars-van Krevelen mechanism, oxygen vacancies of Co3O4 play a significant role in catalytic activity. Herein, we report a novel structure-induced strategy to develop hollow Co3O4 with rich oxygen vacancies for efficient oxidation of CO. Through a reduction-oxidation pyrolysis process, the metal-organic frameworks(MOFs) precursor(i.e., ZIF-67) is transformed into H-Co3O4@H-C, in which hollow Co3O4(H-Co3O4) nanoparticles(NPs) are embedded in hollow carbon(H-C) shell.The hollow Co3O4 NPs feature rich oxygen vacancies and finish a complete conversion of CO at 130°C, which is much lower than that of solid Co3O4(the temperature of full CO conversion T100=220°C). Besides, the hollow carbon shell could also reduce the diffusion resistance during the oxidation process. Benefiting from the unique hollow structures,H-Co3O4@H-C even shows comparable activity to noble metal catalysts under high weight hourly space velocities(WHSVs)up to 240,000 mL h^–1 gcat.^–1. Furthermore, the H-Co3O4@H-C catalyst also shows good durability with only a slight decline after the reaction has been operated for 24 h.