Synthesis And Catalytic Performance Of Spinel Composite Oxide

N-butylaldehyde can be used as resin, plastic plasticizer, vulcanization accelerator, pesticide intermediates. The production of butyl aldehyde is used more propylene carbonyl synthesis. Although the advantages of the method is moderate reaction conditions and the catalyst easily separated, but the ligand is toxic, harmful and other shortcomings. Catalytic oxidation reaction process is simple, atmospheric pollution free, easy separation of each substanc and high utilization, make it become a hot research at home and abroad. In this paper was used the transition metal composite oxide instead of rhodium phosphine complexes, prepared by coprecipitation method, and studied their catalytic oxidation.一、Catalysts Preparation and Characterization1、Different Co based spinel type oxide catalysts was synthesized with NaOH solution as a precipitating agen and cobalt nitrate、zinc sulfate、copper chloride、nickel nitrate、manganese chloride as metal source.We got the catalysts after precipitation, aging, washing, drying and calcinating at 600 ℃ in the muffle furnace. After characterization, the results show that Cu-Mn-Co, Cu-Ni-Co, Cu-Zn-Co, Cu-Co, Zn-Co oxide spinel structure were formed.2、ZnCo2O4 catalyst was prepared at the same method. Characterization methods were XRD, FT-IR, TG and so on. The catalyst was investigated the effects of different calcination temperature on the catalyst structure. XRD analysis showed that the use of co-precipitation method was the precursor spinel structure can be obtained after calcination temperature above 400℃, and divalent metal ions to replace the Co2+enter CO3O4 spinel structure. As the calcination temperature increases, the intensity of the characteristic peaks gradually become strong, when the calcination temperature reached 700 ℃, the spinel structure is changed. FT-IR characterization showed between 500-800cm-1 has two characteristic absorption peak of the characteristic peaks of the spinel structure. TG characterization results of this experiment confirmed the selected calcination temperature is 400-600 ℃ feasible.3、So that the addition of Zn spinel grains become smaller, the catalyst morphology changes, and the Co-O bond is reduced to thereby easily reducing the temperature of the composite oxide increases when the calcination temperature increases, the spinel structure destruction, Zn and Co partial separation, reducing the temperature decreases, the nature close to pure CO3O4, Zn and ZnO reduction temperature was similar.4、The cause of catalyst deactivation is the surface of the Co34 and Co2+ and Zn2+ escape from the composite oxide lattice structure formation ZnO.5、Cu-Co spinel type oxide catalysts was prepared by coprecipitation. After characterization, the results show that one part of Cu2+ formed the cobalt acid copper spinel structure and the other part of Cu2+ formed CuO.二、Catalytic Activity ResearchThe activity of the ZnCo2O4 spinel-type composite oxide catalysts was investigated by n-butanol catalyzed oxidation to n-butyl aldehyde on fixed bed reactor. The influences of reaction such as differentcalcined temperature, different reaction temperature, different oxygen/butanol molar ratio, space velocity, catalyst life were studied.It was found that:ZnCo2O4 spinel complex oxide catalysts for the oxidation of n-butanol has good activity; roasting at a low temperature, degree of crystallinity is not good enough, not high specific surface area, resulting in the catalytic activity is not high, but after calcination temperature is high, than reduced surface area, the surface active sites is decreased, so that the n-butanol conversion rate is lowered, calcined at 500℃ for 2h chosen catalyst. In the calcination temperature was 500℃,the reaction temperature was 380℃, space velocity of the reaction 1h-1, when the molar ratio of 1, ZnCo2O4 effect of the spinel-type composite oxide catalyst is preferably n-butanol conversion was 49.7% selective n-butyraldehyde was 66.2%; ZnCo2O4 spinel composite oxide catalyst roasted at 500℃ oxidated propanol to propionic acid. When the catalytic performance at 420℃ best, at this time the conversion was 61.8% n-propanol, propionic acid selectivity of 61.2%.In conclusion, this experiment was synthesized spinel complex oxide catalytic oxidation of alcohols with good selectivity, with better prospects for industrial applications.