Few-Step Synthesis of PdO/TiO2 and Pd/TiO2 Xerogels

We demonstrate a few-step technique for the synthesis of PdO/TiO2 and Pd/TiO2 (0.1-2.0 wt % Pd) xerogels, which comprises hydrolysis of a palladium nitrate solution in titanium tetrabutoxide in the vapor atmosphere over an aqueous acetic acid solution, drying, and calcination of the material between 800 and 870 degrees C. According to X-ray diffraction and electron microscopy characterization results, after calcination at 800 degrees C the xerogels contained palladium in the form of PdO particles <= 3-5 nm in size. The highly dispersed palladium(II) oxide covered the surface of the rutile crystallites and filled pores in between. Throughout the range of Pd(NO3)(2) concentrations studied, the PdO particles were identical in size. In the material calcined at 870 degrees C, palladium had the form of metallic particles ranging in diameter from 55 to 420 nm. Raising the palladium nitrate concentration in titanium tetrabutoxide was shown to increase the average size of the Pd particles.