title: Operando Synchrotron X-ray Powder Diffraction and Modulated-Excitation Infrared Spectroscopy Elucidate the CO2 Promotion on a Commercial Methanol Synthesis Catalyst.
abstract: Optimal amounts of CO2 are added to syngas to boost the methanol synthesis rate on Cu-ZnO-Al2 O3 in the industrial process. The reason for CO2 promotion is not sufficiently understood at the particle level due to the catalyst complexity and the high demands of characterization under true reaction conditions. Herein, we applied operando synchrotron X-ray powder diffraction and modulated-excitation infrared spectroscopy on a commercial catalyst to gain insights into its morphology and surface chemistry. These studies unveiled that Cu and ZnO agglomerate and ZnO particles flatten under CO/H2 and/or CO2 /H2 . Under the optimal CO/CO2 /H2 mixture, sintering is prevented and ZnO crystals adopt an elongated shape due to the minimal presence of the H2 O byproduct, enhancing the water-gas shift activity and thus the methanol production. Our results provide a rationale to the CO2 promotion emphasizing the importance of advanced analytical methods to establish structure-performance relations in heterogeneous catalysis.
authors.affiliation: ETH Zurich, Department of Chemistry and Applied Biosciences, Institute for Chemical and Bioengineering, Vladimir-Prelog-Weg 1, 8093, Zurich, Switzerland.
authors.forename: Oliver
authors.initials: O
authors.lastname: Martin
authors.affiliation: ETH Zurich, Department of Chemistry and Applied Biosciences, Institute for Chemical and Bioengineering, Vladimir-Prelog-Weg 1, 8093, Zurich, Switzerland.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Mondelli
authors.affiliation: Paul Scherrer Institute, 5232, Villigen, Switzerland.
authors.forename: Antonio
authors.initials: A
authors.lastname: Cervellino
authors.affiliation: Paul Scherrer Institute, 5232, Villigen, Switzerland.
authors.forename: Davide
authors.initials: D
authors.lastname: Ferri
authors.affiliation: Total Research & Technology Feluy, Zone Industrielle Feluy C, 7181, Seneffe, Belgium.
authors.forename: Daniel
authors.initials: D
authors.lastname: Curulla-Ferré
authors.affiliation: ETH Zurich, Department of Chemistry and Applied Biosciences, Institute for Chemical and Bioengineering, Vladimir-Prelog-Weg 1, 8093, Zurich, Switzerland. jpr@chem.ethz.ch.
authors.forename: Javier
authors.initials: J
authors.lastname: Pérez-Ramírez
keywords: carbon dioxide chemistry; heterogeneous catalysis; methanol synthesis; operando characterization; structure-activity relationships