Effect of the Proximity of Pt to Ce or Ba in Pt/Ba/CeO2 Catalysts on NO x Storage-Reduction Performance

The effect of Pt location in Pt/Ba/CeO2 catalysts for NO x storage-reduction (NSR) was analyzed. The Pt location on BaCO3 or CeO2 support was controlled by changing the angle (φ) between the two flame sprays producing these two components. As-prepared flame-made catalysts contain PtO x which must be reduced during the fuel rich phase to become active for NO x storage and reduction of NO x . For Pt on BaCO3 this process was significantly faster than for Pt on CeO2. The increased reduction ability of Pt on Ba is reflected in the light off temperatures: for Pt on CeO2 temperatures around 330°C were needed to combust 20% of C3H6 in air while for Pt on BaCO3 only 250°C were required for the same conversion. The ability to control the location of Pt or other noble metals is, therefore, essential to optimize the catalysts for a given Pt/Ba/CeO2 weight ratio. The best performance was observed when most of the Pt constituent was located near Ba-containing site

Flame-Made Pt/K/Al2O3 for NO x Storage-Reduction (NSR) Catalysts

High surface area Pt/K/Al2O3 catalysts were prepared with a 2-nozzle flame spray method resulting in Pt clusters on γ-Al2O3 and amorphous K storage material as evidenced by Raman spectroscopy. The powders had a high NO x storage capacity and were regenerated fast in a model exhaust gas environment. From 300 to 400°C no excess NO x was detected in the off gas during transition from fuel lean to fuel rich conditions, resulting in a highly effective NO x removal performance. Above 500°C, the NSR activity was lost and not recovered at lower temperatures as K-compounds were partially crystallized on the catalys

Flame-made Alumina Supported Pd-Pt Nanoparticles: StructuralProperties and Catalytic Behavior in Methane Combustion

Bimetallic palladium-platinum nanoparticles supported on alumina were prepared by flame spray pyrolysis. The as-prepared materials were characterized by scanning transmission electron microscopy (STEM), CO chemisorption, nitrogen adsorption (BET), X-ray diffraction (XRD), temperature programmed reduction (TPR), thermogravimetric analysis (TGA) and extended X-ray absorption fine structure (EXAFS) spectroscopy. The materials were tested for the catalytic combustion of methane with a focus on the thermal stability of the noble metal particles. After flame synthesis the noble metal components of the materials were predominantly in oxidized state and finely dispersed on the alumina matrix. Reduction afforded small bimetallic Pd-Pt alloy particles (< 5nm) supported on Al2O3 ceramic nanoparticles. The addition of small amounts of platinum made the palladium particles more resistant against sintering at high temperatures and further lowered the deactivation observed during methane combustio

Independent Control of Metal Cluster and Ceramic Particle Characteristics During One-step Synthesis of Pt/TiO2

Rapid quenching during flame spray synthesis of Pt/TiO2 (0-10 wt% Pt) is demonstrated as a versatile method for independent control of support (TiO2) and noble metal (Pt) cluster characteristics. Titania grain size, morphology, crystal phase structure, and crystal size were analyzed by nitrogen adsorption, electron microscopy and x-ray diffraction, respectively, while Pt-dispersion and size were determined by CO-pulse chemisorption. The influence of quench cooling on the flame temperature was analyzed by Fourier transform infrared spectroscopy. Increasing the quench flow rate reduced the Pt diameter asymptotically. Optimal quenching with respect to maximum Pt-dispersion (∼60%) resulted in average Pt diameters of 1.7 to 2.3 nm for Pt-contents of 1-10 wt%, respectivel

Flame synthesis of supported platinum group metals for catalysis and sensors

Platinum group metals (pgms) supported on a carrier material are widely applied as catalysts. These catalysts are conventionally prepared by wet-phase processes in several steps, while recently developed flame processes allow synthesis of supported pgms in a single step including the support material. Here, we describe flame processes and how finely dispersed supported pgms are made in these flames. So Pt/Al2O3, Pd/ZnO, Rh/Al2O3, Pt/Ba/Al2O3 and others are highlighted regarding their materials properties and performance as catalysts as well as in gas sensors.ISSN:1471-0676ISSN:0032-140

Influence of remote control in Pt/BaAl2O3 NOx storage-reduction catalysts

ISSN:0009-429

Effect of the proximity of Pt to Ce or Ba in Pt/Ba/CeO2 catalysts on NOx storage-reduction performance

ISSN:1022-5528ISSN:1572-902

Flame-Made Pt/K/Al2O3 for NOx Storage–Reduction (NSR) Catalysts

ISSN:1022-5528ISSN:1572-902

Flame-made Alumina Supported Pd–Pt Nanoparticles: Structural Properties and Catalytic Behavior in Methane Combustion

ISSN:1011-372XISSN:1572-879