The Relation between Catalytic Activity of CO Oxidation and Support Structure in Oxidation Catalysts using Gold Nanopart
- PDF / 162,110 Bytes
- 6 Pages / 595 x 842 pts (A4) Page_size
- 99 Downloads / 184 Views
0900-O03-11.1
The Relation between Catalytic Activity of CO Oxidation and Support Structure in Oxidation Catalysts using Gold Nanoparticles Shiho Nagano, Koji Tajiri and Yutaka Tai Materials Research Institute for Sustainable Development, AIST, Anagahora Shimoshidami, Moriyama-ku, Nagoya, 463-8560, Japan ABSTRACT Thiol-passivated gold nanoparticles were adsorbed on several kinds of support materials such as titania-coated silica aerogels and xerogels, and then the thiol was removed by heat treatment. The catalytic activity of the prepared composites for CO oxidation reaction was measured, and the effects of the support on the catalytic activity were investigated. Density of the supports hardly affected the catalytic activity: the reaction rates of aero- and xero- gel composites were almost the same. It was found that the catalysts having high catalytic activity could be obtained by this preparation method, even using the xerogels as the support. Calcination of the supports before adsorption of the gold nanoparticles affected the activity. Different catalytic activities were observed between the composites with and without calcination even when the gold nanoparticles with identical size were adsorbed; thus, it was considered that the surface condition of the support materials affects the state of gold nanoparticles in composite. INTRODUCTION Recently, many studies on gold catalyst have been reported, because gold nanoparticles supported on transition metal oxides show surprisingly high catalytic activity, especially for the oxidation reaction of carbon monoxide[1-3]. The activity is drastically affected by the size of gold nanoparticles[2,4]. However, in most of the preparation methods of the gold catalyst, gold nanoparaticles precipitate on the surface of supports from solution including gold ions, so precise size control is difficult. To prepare the composite with size controlled gold nanoparticles, we have developed a new preparation method[5]. The method is that thiol-passivated gold nanoparticles are adsorbed into a bulk wet gel and then the gel is supercritically dried with carbon dioxide medium. After heat treatment of obtained aerogel to remove thiol group, the aerogel incorporating gold nanoparticles whose size is mostly same as starting thiol-passivated gold nanoparticles is obtained. Thus, if precisely size-controlled thiol-passivated gold nanoparticles is used, it is possible to prepare the composite incorporating size-controlled gold nanoparticles. We reported the gold nanoparticles supported on titania-coated silica aerogel prepared by this method showed excellent catalytic activity of CO oxidation[6]. However, this preparation method has some problems such as considerable time and cost consumptions and inhomogeneous adsorption of the gold. So, we investigated more simple preparation method in which thiol-passivated gold nanoparticles were adsorbed into prepared supports such as aerogels, xerogels and etc.. The effects of support materials on the CO oxidation activity of the catalysts were studied. EXP
Data Loading...
