Highly dispersed gold on activated carbon fibers for low-temperature CO oxidation

Abstract

Gold nanoparticles of 2-5 nm supported on woven fabrics of activated carbon fibers (ACF) were effective during CO oxidation at room temperature. To obtain a high metal dispersion, Au was deposited on ACF from aqueous solution of ethylenediamine complex [Au(en) 2 ]Cl 3 via ion exchange with protons of surface functional groups. The temperature-programmed decomposition method showed the presence of two main types of functional groups on the ACF surface: the first type was associated with carboxylic groups easily decomposing to CO 2 and the second one corresponded to more stable phenolic groups decomposing to CO. The concentration and the nature of surface functional groups was controlled using HNO 3 pretreatment followed by either calcination in He (300-1273 K) or by iron oxide deposition. The phenolic groups are able to attach Au 3+ ions, leading to the formation of small Au nanoparticles (< 5 nm) after reduction by H 2 . This was confirmed by high-resolution electron microscopy combined with X-ray energy-dispersive analysis. The catalyst with high Au dispersion demonstrated high activity in CO oxidation. The surface carboxylic groups decomposed during interaction with [Au(en) 2 ]Cl 3 solution and reduced Au 3+ to Au 0 , resulting in the formation of bigger (> 9 nm) Au agglomerates after reduction by H 2 . These catalysts demonstrated lower activity as compared to the ones containing mostly small Au nanoparticles. Complete removal of surface functional groups rendered an inert support that would not interact with the Au precursor. The oxidation state of gold in the Au/ACF catalysts was controlled by X-ray photoelectron spectroscopy before and after the reduction in H 2 . The high-temperature reduction in H 2 (673-773 K) was necessary to activate the catalyst, indicating that metallic gold nanoparticles are active during catalytic CO oxidation.  2004 Elsevier Inc. All rights reserved.

Development of novel supported gold catalysts: A materials perspective

“…1) [75,83]. The same precursor has also been used by others to prepare Au/NaHY [126], Au/TiO 2 [35], Au/C [127], and Au/clay mineral [128] catalysts. The Au/SBA-15 and Au/MCM-41 catalysts prepared at pH > 8.0 were found to be very active for low-temperature CO oxidation [75,83].…”

Recent Advances in the Liquid‐Phase Synthesis of Metal Nanostructures with Controlled Shape and Size for Catalysis

“…CO oxidation at room temperature was studied using gold nanoparticles synthesized on activated carbon fibre fabrics (157). The particles of 2.5-5 nm showed high catalytic performance, while 9-nm particles were not active.…”

Biogenic Nano-Synthesis; towards the Efficient Production of the Biocompatible Gold Nanoparticles

“…29 Recently, the biosynthesis of biocompatible gold nanoparticles using essential nutritious phytochemicals as well as their possible application in molecular imaging and therapy have been reported. 17,18,28,30 Characterization of gold nanoparticles. To illustrate the size, morphology, solubility, purity, surface chemistry (capping), physical (e.g., crystal structure) and optical properties of the gold nanoparticles produced herein, UV-vis spectroscopy, HR-TEM, XPS, EDS and CD spectral analysis were performed.…”