In situ strong metal-support interaction (SMSI) affects catalytic alcohol conversion

Felipe Polo-Garzon, Thomas F. Blum, Zhenghong Bao, Kristen Wang, Victor Fung, Zhennan Huang, Elizabeth E. Bickel, De En Jiang, Miaofang Chi, Zili Wu

Research output: Contribution to journalArticlepeer-review

66 Scopus citations

Abstract

Strong metal-support interactions (SMSIs) and catalyst deactivation have been heavily researched for decades by the catalysis community. The promotion of SMSIs in supported metal oxides is commonly associated with H2 treatment at high temperature (>500 °C), and catalyst deactivation is commonly attributed to sintering, leaching of the active metal, and overoxidation of the metal, as well as strong adsorption of reaction intermediates. Alcohols can reduce metal oxides, and thus we hypothesized that catalytic conversion of alcohols can promote SMSIs in situ. In this work we show, via IR spectroscopy of CO adsorption and electron energy loss spectroscopy (EELS), that during 2-propanol conversion over Pd/TiO2 coverage of Pd sites occurs due to SMSIs at low reaction temperatures (as low as ∼190 °C). The emergence of SMSIs during the reaction (in situ) explains the apparent catalyst deactivation when the reaction temperature is varied. A steady-state isotopic transient kinetic analysis (SSITKA) shows that the intrinsic reactivity of the catalytic sites does not change with temperature when SMSI is promoted in situ; rather, the number of available active sites changes (when a TiOx layer migrates over Pd NPs). SMSI generated during the reaction fully reverses upon exposure to O2 at room temperature for ∼15 h, which may have made their identification elusive up to now.

Original languageEnglish
Pages (from-to)1938-1945
Number of pages8
JournalACS Catalysis
Volume11
Issue number4
DOIs
StatePublished - Feb 19 2021

Funding

This research was sponsored by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division, Catalysis Science Program. Part of the work including IR, kinetic measurement and electron microscopy was conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility. This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05–00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan ( http://energy.gov/downloads/doe-public-access-plan ).

Keywords

  • Acid-base catalysis
  • Alcohol conversion
  • EELS
  • FTIR
  • SSITKA
  • Strong metal-support interaction
  • Supported-metal catalysts

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