Active sites engineering of metal-organic frameworks for heterogeneous catalysis

Abstract

<p>With the depletion of fossil fuels and global energy crisis confronting us, there is a pressing need for developing economically, environmentally benign and efficient processes in catalytic reactions for chemical synthesis. In comparison to homogeneous catalysis, which is hurdled by metal contamination and limited recyclability, heterogeneous catalysis, which holds multiple advantages of facile separation, recyclability and potential in continues flow reaction systems, is promptly developing field in chemical manufacturing nowadays. Since the first catalytic applications of MOFs reported by Fujita and coworkers in 1994, the use of MOFs in heterogeneous catalysis is under intense investigation. From viewpoint of catalysis, the high design versatility of MOFs renders unparalleled advantages for their applications in catalysis, since it is feasible to rationally engineer not only the active sites but also its chemical environment at the atomic level. Furthermore, the ultrahigh surface area/porosity and periodical structures of MOFs is beneficial to the transportation of reactants/products and guarantee the accessibility of active sites, leading to high activity in catalysis. In principle, the catalytic sites in MOFs can be divided by several categories. 1) The organic linker and the inorganic nodes, which can be induced by direct synthesis or post-synthetic modification; 2) The inner pores of the MOFs can serve as scaffold in which the catalytic species (e.g., metal or metal oxide nanoparticle, metal complex, etc.) is encapsulated;3) The pyrolysis of MOFs to porous carbon or metal/carbon hybrid composites is prone to preserve the merits of MOFs and demonstrate huge potential in heterogeneous and electrochemical catalysis</p> <p>In this dissertation, I present several design of heterogeneous catalysts for desired/model catalytic reactions via active sites engineering in MOFs, that is, using MOFs as scaffold for noble metal NPs and heterogenization of organometallic species and explore its application in catalytic organic transformations; using MOFs as sacrificial templates to prepare monodisperse thiolated Pd NCs or to afford porous carbons with Lewis base sites and investigate its catalytic performance in heterogeneous catalysis. By virtue of MOFs’ tunability, versatility, and flexibility, the rationally-designed MOF catalysts exhibited excellent catalytic performance in tandem catalysis and established a clear structure-activity relationship in the heterogeneous catalysis. Future work on exploring novel and efficient tandem catalysis and elucidate the underlying mechanism of linker engineering in heterogeneous MOFs catalysis in currently undergoing.</p>