Calcination temperature effects on Pd/alumina catalysts: Particle size, surface species and activity in methane combustion

The effects of calcination temperature on Pd/?-alumina catalysts were studied using a variety techniques to measure particle sizes, surface species, and activity in methane combustion. Pd/Al2O3 synthesized new impregnation-vortexing method. Three containing 3.3 wt.% calcined at 150 °C, 250 500 °C. light-off for combustion was 250-255 °C all 100% achieved 275 20 min with the 3Pd/Al2O3 catalyst under lean conditions. X-ray photoelectron spectroscopy showed PdOx PdO surface, conversion some Pd0 after reaction. Particle sizes dispersions different three fresh spent as shown by scanning transmission electron microscopy (STEM) CO pulse chemisorption. In situ operando diffuse reflectance infrared Fourier transform (DRIFTS) that high calcination, dormant monodentate carbonates are formed interface Pd alumina 3 catalyst, which absent during Temperature-responsive species observed both catalysts, evidencing restructuring upon heating accordance STEM results. results indicate varying degree strong metal-support interactions, resulting adsorbed over oxidation We suggest that, desorption frees OH groups Pd-Al2O3 interface, can react (with other or H) desorb water, step be rate limiting low temperatures. This research study highlights possibility altering catalytic properties surfaces through