Synthesis, Characterization Of MIL-88B-derived Magnetic Nanocomposites And Their Catalytic Properties For The Selective Oxidation Of Alcohols

Metal-organic frameworks(MOFs) are a new class of microporous materials, which have been exposively researched in recent years as a result of getting rapid development because of their high specific surface, flexible variable pore and structural diversity characteristics. Simply, this new type of porous material undergo the self-assembly by organic ligands and metal atoms or metal atom clusters to form network structure of zeolite like materials.Through continuous research, researchers found that the MOFs materials have more broad application prospects after loading, packaging or other modifications. Recently, a new research direction based on MOFs with weak bond energy has emerged with the development of the research, which can lead to the skeleton of material collapse under the condition of high temperature. Researchers designed to use the MOFs as sacrificial templates to prepare stable nanoporous carbon materials by pyrolyzing method. These materials have been applied widely in the fields of electrochemical, gas adsorption and separation, etc. However, the application of these materials to catalytic liquid phase organic reaction is rare.In this research, we choose the simple pyrolyzing method for the preparation of nanomaterials as highly active catalysts for liquid-phase catalytic reactions. Since the metal centres of MOFs are separated by organic ligands, it is expected that catalytic particles would be dispersed homogeneous inside the matrix of the framework. MIL-88 B, the non-noble metal-based material, was chosen as a sacrificial template, and the magnetic nanomaterials were prepared by one-step direct calcination in argon atmosphere. The materials were characterized by elemental analysis, PXRD, XPS, SEM and TEM etc. The consequence showed that the magnetic nanomaterial mainly consisted of Fe3O4 and graphite, and also the nanoparticles were distributed evenly without serious aggregation.The prepared magnetic nanomaterials were utilized as catalysts for the selective oxidation of alcohols. So far, the reported catalytic systems for such oxidation of alcohols often involve noble-metal as catalysts, requiring bases as additives or strong oxidizing agent as well as organic solvent. The MOF-derived magnetic nanoparticles by pyrolysis of MIL-88 B showed excellent selectivity and activity in neat water under base-free conditions, featuring a good substrate scope for a variety of aryl and alkyl alcohols with a high selectivity for the target oxidation products. Moreover, the catalysts could be easily recovered and reused for a number of times without significant loss in activity and selectivity.