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

Abstract

The replacement of mercuric chloride in the production of vinyl chloride monomer, a precursor to PVC, would greatly reduce the environmental impact of this large scale industrial process. The validation of single Au cations supported on carbon as the best catalyst for this reaction at an industrial scale has resulted from nearly 35 years of research. In this feature article we review the development of this catalyst system and address the limitations of a range of characterisation techniques used previously which may induce damage to the fresh catalyst. Following our latest findings using X-ray absorption spectroscopy, we show that under operating conditions the catalyst is atomically dispersed and can be classed as a single site catalyst, we give a perspective on future directions in single atom catalysis.

Homocoupling of Phenylboronic Acid using Atomically Dispersed Gold on Carbon Catalysts: Catalyst Evolution Before Reaction

“…recently demonstrated using in situ X‐ray absorption spectroscopy (XAS) studies that the active form of the Au/C catalyst used for acetylene hydrochlorination is comprised of atomically dispersed AuCl x species, which are thermally stable under high‐temperature conditions (i.e., 200 °C) . The acetylene hydrochlorination reaction is proposed to occur through the Au I –Au III redox cycle as predicted through correlations with standard electrode potentials, which suggested to us that this catalyst could also be active as a homocoupling catalyst . In this study, we have investigated this Au/C single‐site catalyst for the homocoupling of phenylboronic acid and compared its performance to that of a sol‐immobilised Au/C nanoparticle catalyst and a simple gold salt (HAuCl 4 ).…”

“…XPS analysis of this 1 % Au/C (AR) sample also suggested the presence of metallic Au. However, it is now well recognised that Au–Cl x species supported on carbon can be susceptible to reduction by the X‐ray flux used in XPS analysis resulting in the generation of Au clusters and nanoparticles from highly dispersed cationic species …”

Highly effective carbon-supported gold-ionic liquid catalyst for acetylene hydrochlorination

“…However, due to continuing efforts to protect the environment, the use of HgCl 2 has been increasingly limited, and its use for the synthesis of VCM has been prohibited since 2013; moreover, a comprehensive mercury-free ban is scheduled to be implemented in 2022. 1 It is thus urgent to search for an alternative mercury-free catalyst for the acetylene hydrochlorination reaction.…”

Synthesis of Vinyl Chloride Monomer over Carbon-Supported Tris-(Triphenylphosphine) Ruthenium Dichloride Catalysts

“…In his initial study the activity of metal catalysts is found to be related with the associated metal ions' standard electrode potentials [1] and AuCl 3 has a higher electrode potential. Subsequently, there was a great deal of research on gold catalysts [2][3][4][5][6][7][8][9][10][11][12][13][14][15]. However, Au-based catalysts do not have their advantages of economic performance because of the high price of Au.…”