Preferential oxidation of CO in H2 over highly loaded Au/ZrO2 catalysts obtained by direct oxidation of bulk alloy

Abstract

The intimate mixture of a skeletal gold structure with ZrO2 nanoparticles obtained simply by oxidation of Au(0.5)Zr(0.5) alloy at room temperature turns out to be an efficient catalyst for the selective oxidation of CO in the presence of hydrogen.

Preparation of Nano-Composited Catalyst from the Bulk Intermetallic Compound AuZr3 with Hydrogen Absorption

“…For pure Zr and Zr hydride before/after calcinations, no activity for CO oxidation was observed. It has been discussed that the interaction between nano-crystalline oxide supports and Au particles acts a major role in enhancing activity of CO oxidation [12,18]. As to this, the results in this study do not deny this possibility, but for a clear conclusion comparison with Au/ZrO 2 prepared by impregnation or co-precipitation is highly desired.…”

“…The oxidation of pure Zr is more facilitated as Zr is alloyed with gold. It should be noted that the intermetallic compound AuZr is easily oxidized even at room temperature [12,16]. Although the mechanism of the oxidation behavior of AuZr is fairly complex [16], gold atoms in this compound promote adsorption and diffusion of oxygen, i.e., gold acts as a catalyst in the oxidation process of AuZr.…”

“…The promising precursors for gold catalysts are restricted in a number of gold-containing alloys and IMCs due to their intrinsic oxidation behaviors. Recently, Lomello-Tafin et al reported that the high surface area and the intimate mixture of a skeletal gold structure with ZrO 2 nano-particles obtained simply by oxidation of the bulk AuZr IMC at room temperature, which turned out to be an efficient catalyst for PROX of CO [12]. However, the oxidation of AuZr was not well controlled due to its spontaneous oxidation.…”

“…Nevertheless, most of the current methods to prepare gold catalysts are not practically easy [8,9]. To overcome this hurdle, gold-containing alloys and IMCs have been used as useful precursors to prepare gold catalysts [10][11][12][13]. Although the gold-containing alloys or IMCs themselves have too small surface area to be used as catalysts, the gold catalysts with certain surface area could be obtained by means of oxidative decomposition.…”

Preparation of Au/TiO2 Catalyst by a Liquid-Phase Reduction Method for Preferential Oxidation of Carbon Monoxide in a Hydrogen Rich-Stream (CO-PROX reaction)

“…Similar results are described in the literature for Au/ZrO 2 catalyst obtained by oxidation of AuZr alloy. This material had Au nanoparticles size of 7 nm and 92% of CO conversion and 55% of CO 2 selectivity at 100ºC 19,20 . A review of Au catalyst for CO-PROX reaction 20 described for Au/ZrO 2 and Au/TiO 2 catalyst with Au nanoparticles sizes of 5 nm a CO conversion of 100% at temperatures in the range of 40-60ºC.…”