Understanding the Deactivation of Gold Catalysts

A new paper just published in ACS catalysis shows the deactivation pathway of single-site gold catalyst for the acetylene hydrochlorination reaction

The acetylene hydrochlorination reaction represent a very important industrial process for the production of vinyl chloride monomer (VCM) that is mainly used to manufacture polyvinyl chloride (PVC), the world’s third-most widely used synthetic polymer after PP and PE.

After the Minamata Convention on Mercury in 2013, the strong drive to replace the traditional toxic mercuric chloride catalyst used in this process, has led to the development and commercialisation of an environmentally friendly Au/C catalyst in China (Johnson Matthey PRICAT^TM MFC).

Recently, with the help of the facilities at the Diamond Synchrotron, a team led by Prof. Hutchings reported an in-situ X-ray Absorption Fine Structure study of these Au/C catalysts under acetylene hydrochlorination reaction conditions, showing the Au/C catalysts are supported analogues of single-site homogeneous Au catalysts operating on a redox couple of Au(I)-Au(III) species (Science 2017, 355, 1399–1403).

Continuing the experimental methodology of previous work, Malta et al. adopted X-ray Absorption and Inelastic Neutron Scattering techniques to gain a greater understanding of the reaction mechanism, providing strong evidence for a concerted HCl and C₂H₂ addition to the Au(I)−Cl active site, and mode of catalyst deactivation. Catalyst deactivation, after C₂H₂ treatment or prolonged time-online studies, was found to be related with the formation of inactive metallic Au particles.

This work is published in ACS Catalysis