Preparation of Bimetallic PdZn nanoclusters and Highly Dispersed PdZn Catalysts Supported on Mesoporous Titania for Synthesis of Fine Chemicals
||Topics in Chemistry and material science
Heron press. 2012.
237 c. ISBN 13140795.
Boreskov Institute of Catalysis SB RAS
PdZn-doped mesoporous titania coatings were synthesized by a sol-gel method using a nonionic structure-directing agent Pluronic F127. Monodispersed PdZn bimetallic colloidal particles have been prepared by an ethylene glycol reduction of ZnCl2 and Pd(CH3COO)2 in the presence of polyvinylpyrrolidone (PVP). Nanoparticles with a predefined and narrow size distribution were incorporated into the support by adding the suspension of colloid nanoparticles directly to the support sol. The structural properties, chemical composition and morphology of the samples were investigated by means of N2 adsorption measurements, TEM, EDS, XRF, ICP-AES and X-ray diffraction. Results suggest how metal particle size, composition and porous structure may be fine-turned to improve the performance of the PdZn/TiO2 catalyst in structure sensitive selective hydrogenation of alkynes. The particle size was obtained in the range of 1.8-4.3 nm by varying PVP, NaOH and precursor concentrations. The bulk composition of nanoparticles depends on concentrations of the precursors and NaOH. The influence of the activation conditions on crystallite size and composition of metal particles was investigated. The high dispersion and chemical composition of the nanoparticles have been retained with no modification after thermal treatment in vacuum at 3000C. Co surfactants such as n-butanol are effective to increase the pore size from 4.9 to 6.8 nm.