Efficient Au⁰/C catalyst synthesized by a new method for acetylene hydrochlorination

Abstract

A Au0/C catalyst for acetylene hydrochlorination was prepared via a novel method and an excellent Au dispersion and catalytic activity was obtained.

Controlling the speciation and reactivity of carbon-supported gold nanostructures for catalysed acetylene hydrochlorination

“…In particular, catalysts exhibiting nanoparticles display activity losses with increasing mean particle size, which can in turn be related to a decreasing population of gold single atoms, demonstrating their central role in acetylene hydrochlorination. In literature, gold nanoparticles and clusters are frequently reported as the active site, but the possible coexistence of gold single atoms was not assessed and conclusions were exclusively based on XPS10,31 or computational results 12,13. Interestingly, the metal dispersion does not suffice as the only catalytic descriptor for gold catalysts in acetylene hydrochlorination, as is evident from the performance of the Au/NC- T series (Fig.…”

“…To guide the rational design of a stable gold catalyst, it is crucial to gain a deeper understanding on the nature of the active site. While to date, various gold species have been identified to be potentially active, including particles,6,10,11 clusters,12,13 and recently also single atoms,14 there remains considerable controversy on their relative activity and the prevailing reaction and deactivation mechanisms. The foremost barriers for a systematic assessment of the influence of gold dispersion and speciation as central catalytic descriptors are: (i) the co-existence of single atoms, clusters and particles in carbon supported gold-based catalysts and (ii) their tendency to sinter under reaction conditions 6–9.…”

Acetylene hydrochlorination using Au/carbon: a journey towards single site catalysis

“…An even stronger correlation was found between activity and standard electrode potential affirming that Au(III) chloride was the active species. 29 Experimental evidence of the presence of cationic Au in active catalysts, predominantly that of Au(III), has been provided by several characterisation techniques; namely 197 Au Mössbauer spectroscopy, 49 Xray photoelectron spectroscopy (XPS) 62,63,64 and temperature programed reduction (TPR). 65,66,61 However, as stated previously most of these techniques either directly show or suggest the coexistence of metallic Au in these samples, which is further corroborated by the frequent observation of metal nanoparticles from several transmission electron microscopy (TEM) studies.…”

“…The observation of high Au(0) content in catalysts from XPS is the primary reason for the repeated assertion, that while cationic Au(III) is the active site, it must exist only on the periphery of Au(0) nanoparticles. 61,50 The observation of only Au(0) in some XPS studies has led some researchers to suggest that Au (0) clusters are themselves the active site 63 .…”

Identification of single-site gold catalysis in acetylene hydrochlorination

“…Ex-situ spectroscopy and electron microscopy (6)(7)(8)(9) studies have suggested that gold nanoparticles are present and the active sites are cationic gold associated with these nanoparticles (6,10). Recently, a possible role for Au(I) as well as Au (III) has been implicated in acetylene hydrochlorination (11) and other reactions (12,13).…”