Hydrothermal Synthesis Of Compound Oxides And Application In Isobutane-Butene Alkylation

Isobutane/butene alkylation has attracted much attation, due to the rising demand for high-octane-index gasoline. The conventional alkylation processing technology uses liquid acid catalysts, such as H2SO4 and HF. However, those liquid acids are unpopular because of their corrosiveness and their toxicity. For these reasons, there is a genuine desire to develop environmental friendly and acceptable solid catalysts. In this work, we synthesized a series of compound oxides by hydrothermal method and researched their catalytic performance.Nanostructured porous WO3/ZrO2 and MoO3/ZrO2 has been synthesized by hydrolyzing zirconium isoproxide in the presence of cationic surfactants: hexaclecylerimethylammonium bromide (CTAB) and structurally characterized by XRD, IR , N2 adsorption-desorption and TEM. Thermochemical behavior and acidity were studied by TG-DTA and NH3-TPD, respectively. For comparison, WO3/ZrO2 and MoO3/ZrO2 prepared by incipient wetness impregnation and sol-gel method are investigated. The X-ray diffraction spectra indicates that the uncalcined samples are amorphous, while cacined samples are crystallized. And the percentage of T-ZrO2 is high. As shown in N2 adsorption-desorption isotherms, the surface area and pore volume of samples are highly increased than samples synthesized previously. The surface area and pore volume tend to decrease after calcinations, while the average pore diameter becomes a bit bigger. According to transmission electron microscope (TEM), the sample shows a structure with a number of wormhole like and displays a "mottled" appearance in the thicker region. The acid test suggests that the acidity highly increased after calcinations.All samples have been tested as catalysts for production of alkylate. The conversion of olefins over different samples is varied. The initial conversions of olefins over IM-W and IM-M are high, and then decreased rapidly. The conversions of olefins over WZO and MZO are higher than that of IM-W and IM-M respectively. The conversions of olefins over WZOA and MZOA are higher than those of others. The products over different samples are alike. The changing of catalysts can only vary the ratio of products. For different samples, the yields of C8 are in the following order: IM-W>WZO>WZOA (or IM-M>MZO>MZOA). It could be attributed to the stronger acid strength and the more acid amount of WZOA (or MZOA).