Metal-organic Frameworks And Their Derivatives For Heterogeneous Catalysis

Metal-organic frameworks (MOFs), as a relatively new class of organic-inorganic hybrid crystalline porous materials, feature versatile and tailorable structures as well as very high surface areas and thus exhibit potential applications in various fields, such as gas storage, separation, molecular detection, drug delivery, bio-medicine and catalysis. And the MOF-based heterogeneous catalysis is one of the most promising applications. In addition, MOF-based catalytic activity mainly depends on two reasons:the metal centers and organic ligand, endowing MOFs with powerful functionality in heterogeneous catalysis. Particularly, a high density of active sites are evenly distributed throughout the space of MOFs and facilitate the contact with catalytic substrate, while the pore structure greatly facilitates the transfer of substrate and product.In recent years, the application of nanostructures of metallic materials, has aroused extensive research interest. Since the MOFs are rich in various metal ions and organic ligands, MOFs-based material has a natural advantage of being a template or a precursor under appropriate calcination conditions, to yield the porous carbon or the composite structure of porous carbon with metals, metal oxides, metal sulfides. The resulting material shows prospects in the energy and environmental fields, and particularly in catalysis.This paper is mainly based on the two aspects above, engaging in research of several parts:1. By a post-processing method, a～100% sulfonic acid functionalized metal-organic framework (MOF), MIL-101-SO3H, having both Lewis acid sites and Bronsted acid sites, can behave as an excellent solid acid catalyst. Experimental results show that the Bronsted acid sites in MIL-101-SO3H, with good activity, selectivity, and stability for the oxidation of styrene ring-opening reaction. Its catalytic performance is superior to all previous reports of MOF-based catalysts.2. A Co-based metal-organic framework, ZIF-67, has been exploited as a self-template to afford a CoO-Co@N-C nanocomposite structure and the material obtained at different calcination temperatures, calcination times were characterized. The materials exhibit excellent catalytic activity, and selectivity toward the direct oxidation of alcohols to esters with O2 as a benign oxidant under mild conditions. The experimental results show that the catalytic properties of the composite structure are much better than ordinary composite Co with activated carbon. Furthermore, the magnetic properties of Co allow the material to be conveniently recycled with external magnets.3. The γ-Fe2O3 nanoparticles well dispersed in porous carbon were fabricated via a Fe-based metal-organic framework-templated one-step pyrolysis. Under different calcination conditions were given the different forms of Fe, such as γ-FeiO3, α-Fe and Fe3C. It showed that having γ-Fe2O3 as the major product of Fe-500-lh nanocomposites, the catalyst exhibited excellent catalytic activity, chemoselectivity, magnetic recyclability and excellent cycle stability for the hydrogenation of diverse nitro compounds under mild conditions.