Synthesis of nanostructured Pt/CeO2–ZrO2–Al2O3catalysts by a two-step sol–gel method

Porous Pt / CeO 2 –ZrO 2 –Al 2 O 3 catalysts were synthesized by a two-step sol–gel method in which noble metal nanoparticles were first prepared as a dispersed colloid in an aqueous medium, then mixed with aluminum isopropoxide (AIP), Ce(NO 3 ) 4 and Zr(NO 3 ) 4 , and condensed into a gel. After calcination at 800 °C for 3 h, these composite catalysts showed large specific surface areas (150–160 m 2 g −1 ) and a narrow pore size distribution of 10–12 nm as determined from the nitrogen adsorption/desorption isotherms. XPS and TEM scans showed that the active component of the catalyst was well dispersed, with the Pt nanoparticles (particle size 3–5 nm) confined to the pores. It was found that changing the template surfactants from ionic cetyltrimethylammonium bromide (CTAB) to non-ionic polyethylene glycol P-1,1,3,3-tetramethylbutylphenyl ether (TritonX-100) did not change either the specific surface area or the pore structure, but lowered the CO-to-CO 2 reaction temperature by nearly 60 °C. Measurements of CO conversion proved that the catalyst prepared with TritonX-100 as the template had the highest catalytic activity: the onset of the conversion of CO to CO 2 began at 158 °C and was complete at 192 °C. The possible mechanism of the anti-aggregation of nanoparticles and high catalyst activity has been discussed. Corrections were made to table 2 in this article on 16 August 2007. The corrected electronic version is identical to the print version.