Study On The Preparation Of Novel La₂O₃/AAO Nanoarray Catalyst

As the result of the characteristics of tiny unit structure, high surface energy, high surface atom ligand saturation and high specific surface area, nanometer catalyst materials have drawn wide attention, they have a better adsorption potential and higher catalytic activity than the conventional materials. When the active component is implanted into a template with a specific hole structure, a higher specific surface area is obtained and the operation difficulty caused by the small granularity is avoided. In numerous templates,porous anodic alumina oxide(AAO) template is often used as a catalyst carrier because of its ordered structure, high temperature resistance and simple preparation. Considering the structure of the catalytic material order, specific surface area, thermal stability, preparation difficulty and laboratory equipment, we choose the sol-gel combined with template method for preparation of nanometer catalyst.In this paper, the method to make the catalyst carrier is used by anodic oxidation. The high purity aluminum sheet is used as substrate, AAO is prepared on the surface of the porous alumina membrane by one step anodic oxidation method. Then the inverse electrical stripping method is used to separate the AAO and aluminum matrix, thus the AAO template is obtained. Lanthanum nitrate is used as the source of lanthanum, citric acid as a chelating agent, and we choose sol-gel method to control the parameters of experimental conditions, precursor is implanted into hole of template by means of negative pressure suction filter and at last we use the guiding role of template to synthesis the new type La2O3/AAO nanoarray catalyst.The catalytic activity of the catalyst is tested using aldol condensation of acetone to diacetone alcohol as a probe reaction. The catalyst is characterized by XRD, SEM, TEM,BET and CO2-TPD.The results show that the optimum condition is as follows: the calcination temperature is 900 ℃ and the calcination time is 1 h. Under the above conditions, the conversion of acetone is 4.01 % and the selectivity towards diacetone alcohol is 96.32 %. The conversion of acetone is 3.63 % and the selectivity to diacetone alcohol is 97.06 % after 5 runs. La2O3 is highly and homogeneously dispersed on the AAO surface. The activity and selectivity of La2O3/AAO catalyst is attributed to its larger specific area, weak basic sites and a large basic amounts.