Nanoscale lanthanum oxide catalysts for self-condensation of acetone: preparation via self-assembly on anodic aluminum oxide, structure, and properties

Abstract

A novel structured La2O3/AAO solid base catalyst was prepared by supporting lanthanum oxide (La2O3) on the surface of anodic aluminum oxide (AAO) under hydrothermal conditions. Catalytic activity of the catalyst was tested using self-condensation of acetone to diacetone alcohol as a probe reaction. The conversion of acetone reached 4.14 % with the diacetone alcohol selectivity of 98 %. The catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy disperse spectroscopy (EDS), thermogravimetric analysis (TGA), N2 adsorptiondesorption (BET), and temperature programmed desorption (CO2-TPD). XRD patterns and SEM images indicated that La2O3 nanoscale particles with high crystallinity were uniformly distributed over the AAO surface. The results of CO2-TPD showed that the calcination temperature led to the formation of medium-strength basic sites, strong basic sites, and to an increase of the basic strength. The strong basic sites and large basic strength are an important factor that influences the catalytic activity in the self-condensation of acetone to diacetone alcohol.