Preparation And Catalytic Properties Of Noble Metal-ACID Bifunctional Catalyst Based On MIL-101

Metal organic frameworks (MOFs) are a class of crystalline materials built with multi-topic organic ligands and metal ions which have regular network structures and high surface area. Due to these outstanding properties, MOFs would be ideals and promising materials for applications in heterogeneous catalysis. However, due to limited catalytically active centers on MOFs, it needs to be further functional modification. In this thesis, based on the property and structure features of MIL-101, we used different methods to modify MIL-101 with noble metal and acid active centers and obtained a novel bifunctional heterogeneous catalyst. Then we applied these bifunctional catalysts in the hydrodeoxygenation of two biomass-based model compounds, and investigated the relationship between the structure and catalytic properties. The main results of this thesis are summarized as follows:(1) A sulfonic acid-functionalized MIL-101 (SO3H-MIL-101) was synthesized by using monosodium 2-sulfoterephthalate as organic ligand in short time, and this catalyst was systematically characterized by various techniques including XRD, FT-IR, XPS and N2 adsorption. The catalyst shows excellent catalytic performance and stability in the acetal reaction and superior to the traditional zeolite and Amberlyst-15 catalyst.(2) Pt@SO3H-MIL-101 which coupled with Pt nanoparticels and sulfonic acid moieties was prepared by an incipient-wetness impregnation method, and then applied in the hydrodeoxygenation of methyl isobutyl ketone (MIBK) in a fixed-bed reactor. The characterization results show that the skeletal structure and activity centers of the Pt@SO3H-MIL-101 catalyst are stable under the investigated reaction conditions, By varying the Pt loadings, a maximum yield of 2-methyl pentane (73.9%) can be achieved over the catalyst with 2.0 wt.% Pt loading. And the process of MIBK hydrodeoxygenation would follow the bifunctional mechanism which involves a series of hydrogenation and deoxygenation reactions, was demonstrated by the designed experimental.(3) A highly efficient multifunctional catalyst made of Pd nanoparticles immobilized on a mesoporous sulfonic acid-functionalized metal-organic framework SO3H-MIL-101, Pd@SO3H-MIL-101, was developed, which exhibits a high catalytic performance in promoting biomass refining. The use of SO3H-MIL-101 as a support renders highly dispersed Pd nanoparticles with uniform size distribution, sufficient reactants contact in aqueous media, and more easily activation the reactant induced by the Br(?)nsted acid coordination (sulfonic acid groups from SO3H-MIL-101). Thus, the resultant 2.0 wt.%Pd@SO3H-MIL-101 catalyst showed novel synergy in hydrodeoxygenation of vanillin (a typical model compound of lignin) at low H2 pressure under mild conditions in aqueous media. Excellent catalytic results could be achieved (100% conversion of vanillin with exclusive selectivity for 2-methoxy-4-methylphenol), and no loss of catalytic activity and selectivity were observed after seven recycles in succession.