Alcohol-Induced Low-Temperature Blockage of Supported-Metal Catalysts for Enhanced Catalysis
Felipe Polo‐Garzona✉, Thomas F. Blumb, Victor Fungb, Zhenghong Baoa, Hao Chenc, Zhennan Huangb, Shannon M. Mahurina, Sheng Daia c, Miaofang Chib, Zili Wua b✉
- aChemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
- bCenter for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
- cDepartment of Chemistry, The University of Tennessee, Knoxville, Tennessee 37996, United States
- ✉Corresponding author
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Abstract
The partial or complete blockage of active sites of metal nanoparticles (NPs) on supported-metal catalysts has been of interest for tuning the stability, selectivity, and rate of reactions. Here, we show that Au-sites in Au/TiO 2 surprisingly become blocked upon treatment in common alcohols (2-propanol and methanol), with 2-propanol causing a greater extent of blockage. Nearly 95% of Au-sites are covered after treatment in 2-propanol at room temperature, followed by desorption at 150 °C. Infrared spectroscopy of CO adsorption unambiguously confirms the occurrence of this phenomenon. Electron energy loss spectroscopy (EELS), temperature-programmed desorption (TPD), Raman spectroscopy, and DFT simulations suggest that the formation of carbon deposits from 2-propanol decomposition and/or the migration of a TiO x layer over the supported NPs may be responsible for the blockage of Au-sites. Nearly full coverage of Au NPs after treatment in 2-propanol led to negligible activity for catalytic CO oxidation, whereas partial retraction of the overlayer led to enhanced activity with time-on-stream, suggesting a self-activating catalytic performance.