The Effect of Pretreatment On Electrostatically Adsorbed Noble Metal Precursors

One of the most important concerns in catalyst synthesis is the metal particle size.  After impregnation of the support with the metal precursor, the pretreatment conditions of the catalyst play a crucial role in determining the final metal particle size.  This correlation has been indirectly investigated by various studies, but hasn’t been systematically examined.  This research project deals with the influence of temperature and heating rate during the reduction process in H₂ flow on Pt and Pd particle size on various supports, both low PZC (oxidized carbon, TiO₂, SiO₂) and high PZC (carbon, Al₂O₃).  The influence of humidity during reduction is also dealt with for the Pt catalysts.  The catalysts are synthesized by dry impregnation (DI) and strong electrostatic adsorption (SEA).  Particle size analyses are done by XRD and STEM imaging.