Support Effect in High Activity Gold Catalysts for CO Oxidation

Abstract

In this work, we present a detailed study concerning the evaluation of the metal-support interaction in high activity gold catalysts for CO oxidation. Using the colloidal deposition method, model catalysts were prepared, which allow the isolation of the effect of the support on the catalytic activity. Prefabricated gold particles were thus deposited on different support materials. Since the deposition process did not change the particle sizes of the gold particles, only the influence of the support could be studied. TiO2, Al2O3, ZrO2, and ZnO were used as support materials. Catalytic tests and high resolution transmission electron microscopy clearly show that the support contributes to the activity. However, our results are not in line with the distinction between active and passive supports based on the semiconducting properties of the oxidic material. The most active catalysts were obtained with TiO2 and Al2O3, while ZnO and ZrO2 gave substantially less active catalysts. Furthermore, the effect of other important parameters on the catalytic activity (i.e., particles size distribution, calcination temperature, and aging time for a Au/TiO2 catalyst) has also been studied. Using this preparation route, the catalysts show high-temperature stability, size dependent activity, and a very good long-term stability.

Probing Oxide Reduction and Phase Transformations at the Au-TiO2 Interface by Vibrational Spectroscopy

“…4 nm diameter were deposited on commercial anatase TiO 2 (specific surface area of ~300 m 2 g −1 ; material consists of almost round nanoparticles with a diameter of 10-20 nm; Sachtleben Chemie GmbH, now: Huntsman P&A Germany) and on P25 (specific surface area approximately 50 m 2 g −1 ; rutile/anatase = 20/80; Evonik Industries AG) by the colloidal deposition method as described in Refs. [45][46][47]. One sample was prepared similarly, but not calcined after the colloidal synthesis (Au/anatase uncalc.).…”

Synthesis of Gold Catalysts Supported on Mesoporous Silica Materials: Recent Developments

“…Gold colloids and nanoparticles have been prepared by different procedures and used as precursors to prepare gold supported on TiO 2 , ZnO, ZrO 2 , Al 2 O 3 , carbon and SiO 2 materials [32,[149][150][151][152][153][154][155][156][157]. The synthesis of gold supported on MSM using gold colloids or presynthesized AuNPs can be achieved by using two different strategies: (i) dispersing the presynthesized gold precursors on the MSM support and (ii) synthesizing the MSM in the presence of presynthesized gold colloids or AuNPs.…”

Interfacial activation of catalytically inert Au (6.7 nm)-Fe3O4 dumbbell nanoparticles for CO oxidation

“…While the particle size of gold nanoparticles is important in optimizing the catalytic activity, the selection of appropriate supports has also been found critical to achieving high catalytic performance and stability of supported gold nanoparticles. In most cases, the size and support effects are likely to operate simultaneously [14], due to the lack of highly reproducible techniques for the controlled preparation of well-defined goldnanoparticle catalysts, separation of size and support effects therefore remains a challenge [15,16]. For example, the importance of the Au TiO 2 interface in CO oxidation over real catalysts has been widely proposed and investigated by comparison of various supported gold nanoparticles or between supported TiO 2 -supported Au nanoparticles and unsupported gold powder [17 20].…”