الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Metal organic frameworks (MOFs) are a unique class of hybrid porous materials in which metal ions or clusters are interconnected through polyfunctional organic ligands. Compared to conventional microporous and mesoporous inorganic materials, these metal–organic structures exhibit advantages such as unprecedented internal surface areas (up to 10000 m2g-1), tunable and extra large pore sizes, an intrinsically high metal content, structural diversity, crystalline open structures and the ease of processability, flexibility and geometrical control. These outstanding properties render MOFs nascent candidates for being used as heterogeneous catalysts, catalyst supports and adsorbents.
The main objective of this thesis was to synthesize nano-functionalized MOFs for applications in heterogeneous catalysis (oxidative desulfurization of organosulfur compounds and oleic acid esterification) and liquid phase adsorption (sulfur compounds from fossil fuels).
In chapter 2, for the first time, vanadium-substituted phosphomolybdic acid (V2MPA) was successfully immobilized on the surface of amino-functionalized chromium terephthalate metal–organic framework MIL-101(Cr) by means of chemical bonding to the amino groups. The synthesized catalyst was characterized by powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR) and N2 adsorption–desorption isotherms. The characterization results revealed that the structures of the parent support and the Keggin [PV2Mo10O40]-5 anions remained almost unaltered in the immobilized catalyst. The catalytic activity of the newly synthesized hybrid catalyst was first assessed in the oxidative desulfurization of a model fuel containing dibenzothiophene (DBT) using 30% aqueous hydrogen peroxide as the oxidant and acetonitrile as the polar solvent. The present catalyst exhibited a high catalytic activity in the oxidative desulfurization process comparable to that of the homogenous V2MPA catalyst. Dibenzothiophene could be removed completely under xx
the following optimum conditions: reaction temperature of 70 °C, reaction time of 60 min., 10 g/L catalyst and H2O2/DBT molar ratio of 6. Interestingly, after catalysis, this catalyst can be readily separated from the reaction mixture by simple filtration and recycled five times without leaching and loss of activity. The excellent recyclability was ascribed to the strong interaction between the amino groups on the surface of MIL-101(Cr) and the V2MPA species anions. Additionally, kinetics parameters of the catalytic oxidation of DBT were measured and calculated. Finally, the optimum reaction parameters found were employed for ODS of real gas oil sample.
Deep desulfurization of petroleum-based fuels via π-complexation adsorption is an effective and powerful technology for the selective removal of aromatic sulfur compounds. In chapter 3, a series of silver nitrate loaded HKUST-1 (Copper benzene-1,3,5-tricarboxylate, Cu-BTC MOF) adsorbents with different silver nitrate loadings were synthesized and evaluated as adsorbents for the adsorptive removal of benzothionphene (BT) BT as a typical organosulfur compound from model liquid fuel. The results showed that the incorporation of Ag(I) ions into the HKUST-1 framework considerably improved the adsorption capacity for BT. The improved adsorptive performance might be ascribed to π-complexation interaction between Ag(I) ions and the organo-sulfur compound. Experiments have been performed to study the effects of the silver nitrate loading, contact time, adsorption temperature, adsorbent dose and BT initial concentration on BT adsorption. Langmuir isotherm model was used to study the adsorption of BT on silver nitrate containing adsorbent. The kinetic results showed that the adsorption process was best described by the pseudo second-order kinetic model. Thermodynamic parameters, including free energy of adsorption (ΔGo), enthalpy (ΔHo), and entropy (ΔSo) changes, were calculated to predict the nature of the adsorption process.
Biodiesel is a promising renewable alternative to the traditional petroleum-derived diesel fuel. Biodiesel production from cheap materials involves an essential pretreatment xxi
step, esterification of free fatty acids (e.g. oleic acid), for avoiding soap formation and catalyst deactivation. In chapter 4, zirconium terephthalate metal-organic framework (UiO-66(Zr)) bearing sulfonic acid groups was synthesized via postsynthetic modification (PSM) of the organic linkers within the MOF with chlorosulfonic acid. This MOF was systemically characterized via XRD, N2 adsorption and FT-IR techniques, and then used as a heterogeneous catalyst for oleic acid esterification with ethanol. Various reaction parameters, such as ethanol/oleic acid molar ratio, catalyst dosage, reaction temperature and time were systematically investigated. The obtained SO3H-UIO-66(Zr) catalyst exhibited good catalytic performance in the esterification of oleic acid and also showed good reusability. The conversion of oleic acid can reach up to 88% and the catalyst can be reused for at least five times in succession without remarkable loss of catalytic activity.