Two dicationic ionic liquids, 3,3'-(1,4-phenylene bis(methylene))bis(1-methyl-1 H -imidazol-3-ium) bromide and 3,3'-(butane-1,4-diyl)bis(1-methyl-1 H -imidazol-3-ium) bromide were synthesized and named as DIL-A and DIL-L, respectively. In addition, two molecular sieves MCM-41 and Al-MCM-41 were prepared. This thesis is based on these precursors contains three projects. (I) Four dicationic ionic liquids (DIL)/heteropoly acid (HPA) composites were prepared and used for oxidation of cyclohexene with molecular oxygen in the absence of the solvent. To achieve a modified structure of the composites, semi-empirical calculations were used. All effective parameters on the reaction such as temperature, oxygen pressure, time, amount of catalyst and types of both HPA and DIL were investigated. The maximum conversion (96%) belonged to DIL-L/ tungstophosphoric acid (DIL-L/W) catalyst, and maximum selectivity (86%) was attributed to cyclohexene-1-one. (II) A DIL-A-based palladium- N -heterocyclic carbene complex (NHC-Pd) was synthesized and heterogenized using TiO 2 matrix. The NHC-Pd@TiO 2 catalyst was insoluble in water. It was employed in the Suzuki-Miyaura coupling reaction involving aryl halides with phenylboronic acid, potassium carbonate, and H 2 O/EtOH as the solvent. (III ) Two molecular sieves, MCM-41 and Al-MCM-41, were synthesized and modified with activated carbon and graphitic carbon nitride. Adsorption of nitrobenzene (NB) from aqueous solution onto mesoporous silica materials, i.e., pyrolyzed MCM-41 (Si-C), pyrolyzed Al-MCM-41 (Al-C), MCM-41 containing g-C 3 N 4 (Si-C 3 ) and Al-MCM-41 containing g-C 3 N 4 (Al-C 3 ) was investigated. The maximum adsorption capacity of sorbents belonged to Al-C (243.9 mg/g). It is noticeable that structural characterization of the precursors, composites, and adsorbents was carried out by different techniques such as ICP, FT-IR, 1 H { 13 C} NMR, BET, TGA, XRD, XPS, TEM, FESEM and EDX-Map. GC and GC-MS analysis was conducted to determine the products and their amounts.
