Highly dispersed Pt nanoparticle catalyst prepared by atomic layer deposition

Nanoparticulate platinum has been well dispersed onto large quantities of micron-sized mesoporous silica gel using atomic layer deposition in a fluidized bed reactor (i e ALD-FBR). Transmission electron microscopy (TEM) cross-sectional investigations showed that the Pt nanoparticles were homogeneously distributed throughout primary 30-75 mu m silica gel particles, including the inner surfaces comprising 5-7 nm pores. The Pt catalyst loading level was tightly controlled by the number of coating cycles An extremely low Pt loading with 3.1 x 10(-6) mg Pt/cm(2) (0 10 atom/nm(2)), 48 x 10(-6) mg Pt/cm(2) (0 15 atom/nm(2)) and 2.9 x 10(-5) mg Pt/cm(2) (0 91 atom/nm(2)) was prepared with 3.5 and 10 coating cycles, respectively The average Pt particle size is approximately 1 2 nm for 3 cycles For 5 and 10 coating cycles. the Pt particle size is measured to be 1 9 nm and 2 3 nm. respectively. The sample with a 3 1 x 10(-6) mg Pt/cm(2) loading exhibits the highest metal dispersion of 90% Thermal stability studies indicated an initial sintering of the Pt particles during the first 4 h of heat treatment at 450 degrees C in an air environment. After that, there was no noticeable change of the particle size during the following heat treatment process Carbon monoxide oxidation demonstrated nearly 100% conversion of CO to CO2 over 20 mg of 4 8 x 10(-6) mg Pt/cm(2) loaded silica gel particles at 180 degrees C for 100 sccm flow rate of 1% CO in argon (C) 2010 Elsevier B.V. All rights reserved