Preparation Of Monodisperse Mesoporous Composite Catalysts And Research On Their Catalytic Performance

Ordered mesoporous silicas have attracted considerable concerns due to their greatly potential applications in environment, industrial catalysis and other fields. In this work, highly dispersed mesoporous composites were prepared via a simple incipient wetness co-impregnation route by casting furfurylalcohol (FA) solution of metallic salts, which were used as carbon and metal sources, respectively, into the channels of molecular sieves KIT-6, followed by the subsequent removal of the carbon resulted from carbonized FA. Four types of mesoporous composites were prepared according to the loaded metals:Mo-KIT-6, Mn-KIT-6, Cu/Ce-KIT-6 and Fe/Cu/Ce-KIT-6. The composites catalysts were characterized by X-ray diffraction(XRD), N2 adsorption-desorption, UV-visible absorption spectroscopy (UV-vis), Fourier transform infrared spectroscopy(FT-IR), inductively coupled plasma emission spectroscopy (ICP-AES), X-ray photoelectron spectroscopy (XPS), electron paramagnanetic resonance (EPR), Raman spectroscopy (Raman), temperature programmed desorption of ammonia (NH3-TPD) and transmission electron microscope(TEM), and the catalytic performance were tested with different reactions, respectively.The characterized results of Mo-KIT-6 catalysts showed that Mo species were highly dispersed onto the pore surface of KIT-6 with loading amount of molybdenum less than 4%. The catalysts exhibited higher activity and selectivity in the epoxidation of cis-cyclooctene. The most efficient sample can give a yield of epoxyoctane as high as 100% in 30mins. Reusability and stability were demonstrated with high activity after 6 runs.The results showed that Mo-KIT-6 catalysts are ideal green ones for epoxidation reactions.For Mn-KIT-6, it is showed that Mn species were highly dispersed onto the pore surface of KIT-6 with well maintance of the highly ordered mesoporous structure, high surface area and large pore volume of KIT-6. The catalysts exhibited high activity and selectivity in the eterification of N-butanol and acetic acid, on the yield of butyl acetate as high as 97% in 4h. The reusability and stability were demonstrated with high activity after 5 runs.For Cu/Ce-KIT-6, it is showed that copper and cerium species could be highly dispersed when the content of cerium is higher than copper species in the impregnating mixture. The catalysts exhibited good activity in the CO oxidation reaction, with 100% conversion of CO at 170℃. The stability was demonstrated with high activity with the temperature increased to 400℃.As for Fe/Cu/Ce-KIT-6, the catalysts were demonstrated to maintain highly ordered mesoporous structure after loading iron, copper and cerium species, simutaneously. The catalysts exhibited good activity in the CO oxidation reaction, on the conversion 100% of CO at 145℃. The stability was verified with high catalytic activity at temperature of 400℃.