Molecular Oxygen Oxidation Synthesis Of Isoamyl Alcohol Step Isovaleric Acid Isoamyl Acetate Catalyst Research

The dioxygen being as the oxidation and the transition metal oxide being as the main catalyst were used in the direct synthesis of isoamyl isovalerate from isoamyl alcohol in this paper. Thereinto, the catalytic performance of different catalysts was explored and evaluated by the conversion of isoamyl alcohol, yield and selectivity of isoamyl isovalerate. The catalyst samples were characterized by techniques such as BET, XRD, SEM, FT-IR, and TPD and so on, which were connected to the catalytic performance of catalysts. The technology conditions of the synthesis were optimized, including the catalyst dosage, reaction temperature and reaction time. The catalyst stability, reaction mechanism and kinetics were studied too.The different metal oxide catalysts loaded on the SiO2were prepared by isovolumetric impregnation method and Fe2O3、ZnO and Cr2O3were the acticve component due to their better catalytic performance. The prepare conditions of catalysts were explored, which were connected to the different characterization method, at the same time, the catalysts under the best prepare condition were decided. The result indicates that the metal oxide loading and calcination temperature have greater influence on the specific surface area and pore diameter of catalyst, which affect the catalytic performance of catalyst further more. Thereinto, the6%Fe2O3-4%ZnO/SiO2and1%Cr2O3-4%ZnO/SiO2exhibited the better active performance when the calcination temperature was500℃. The conversion of isoamyl alcohol was57.6%, yield and selectivity of isoamyl isovalerate was31.4%and54.5%by the former; the conversion of isoamyl alcohol was65.7%, yield and selectivity of isoamyl isovalerate was36.8%and56.0%by the latter.The different metal spinel catalysts were prepared sol-gel process and Fe and Zn were the acticve component due to their better catalytic performance. The ZnFe2O4-SO42-catalysts were studied after the ZnFe2O4spinel had been modified by the vitriol. The result indicates that vitriolic concentration, calcination temperature and time have greater influence on the specific surface area, pore diameter and acidity of catalyst. ZnFe2O4spinel roasted at700℃being as the base, the best prepare conditions of ZnFe2O4-SO42-were listed as follows: vitriolic concentration was0.75mol/L, calcination temperature was500℃, calcination time was3h. The conversion of isoamyl alcohol, yield and selectivity of isoamyl isovalerate were up to53.6%、27.8%and51.9%respectively at the best prepare conditions.The technology conditions of the synthesis were optimized and decided with the 1%Cr2O3-4%ZnO/SiO2being as the catalyst. The conversion of isoamyl alcohol was65.7%, yield and selectivity of isoamyl isovalerate was36.8%and56.0%when the technology conditions were listed as follows:isoamyl alcohol dosage was30mL, catalyst dosage was0.9g, oxygen flow was25mL/min, reaction temperature was120℃, and reaction time was9h. As to the reaction mechanism of isoamyl isovalerate, the synthesis reaction was conducted by "Aldehyde oxidation and esterification mechanism". The kinetics research indicates that the reaction activation energy was decreased to112.9kJ/mol and the reaction energy barrier was reduced enormously because of the catalyst.