Carbon supports are ubiquitous components of heterogeneous catalysts for acetylene hydrochlorination to vinyl chloride, from commercial mercury-based systems to more sustainable metal single-atom alternatives. Their potential co-catalytic role has long been postulated but never unequivocally demonstrated. Herein, we evidence the bifunctionality of carbons and metal sites in the acetylene hydrochlorination catalytic cycle. Combining operando X-ray absorption spectroscopy with other spectroscopic and kinetic analyses, we monitor the structure of single metal atoms (Pt, Au, Ru) and carbon supports (activated, non-activated, and nitrogen-doped) from catalyst synthesis, using various procedures, to operation at different conditions. Metal atoms exclusively activate hydrogen chloride, while metal-neighboring sites in the support bind acetylene. Resolving the coordination environment of working metal atoms guides theoretical simulations in proposing potential binding sites for acetylene in the support and a viable reaction profile. Expanding from single-atom to ensemble catalysis, these results reinforce the importance of optimizing both metal and support components to leverage the distinct functions of each for advancing catalyst design.
Contact
Dr Adam H. Clark
Debye beamline
Operando spectroscopy group & Laboratory for Synchrotron Radiation and Femtochemistry (LSF)
Swiss Light Source, Paul Scherrer Intitute
5232 Villigen-PSI, Switzerland
Telephone: +41 56 310 58 05
E-mail: adam.clark@psi.ch
Original Publication
Evidence of bifunctionality of carbons and metal atoms in catalyzed acetylene hydrochlorination
Vera Giulimondi, Andrea Ruiz-Ferrando, Georgios Giannakakis, Ivan Surin, Mikhail Agrachev, Gunnar Jeschke, Frank Krumeich, Núria López, Adam H. Clark & Javier Pérez-Ramírez
Nature Communications, 9 September 2023