Support effect in the preparation of supported metal catalysts via microemulsion

摘要

It is well known that the activities of supported metal catalysts are strongly dependent upon the size, shape and dispersion of the nanoparticles on the support material. There are several techniques which can be implemented in order to produce such catalysts, e. g. wet impregnation, however the deposition of nanoparticles (NPs) on the support material without agglomeration still proves a challenge. This is particularly significant when attempting to maintain the size and shape of the particles during the deposition process. We have introduced a new method to deposit metal NPs, namely thermodestabilization of microemulsions (please see J. Mater. Chem., 2012, 22, 11605-11614 and Nanoscale, 2013, 5, 796-805), in which the NPs are formed prior the deposition process. This method is an ingenious approach to control the dispersion of NPs on the support material and depositing NPs evenly with a narrow size distribution. In this paper we expound the important role of the surface charges of NPs and the support material, as indicated by zeta potentials, on the metal dispersion, and how they affect the catalytic activity. We also investigate the influence of other parameters such as the pore size and the pre-calcination of the support on the catalytic activities of the resulting supported metal catalysts.