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Title: Insight into the Selectivity of Isopropanol Conversion at Strontium Titanate (100) Surfaces: A Combination Kinetic and Spectroscopic Study

Abstract

This work aims to better understand the role of interfacial molecular structure that governs selectivity and activity in heterogeneous catalytic reactions. To address this, a comprehensive study of isopropanol conversion over an archetypal perovskite material, strontium titanate (SrTiO 3 or STO), was performed with an array of techniques sensitive to orthogonal aspects of the ensuing chemistry. Cubic-shape STO nanoparticles with only the (100) facet exposed were synthesized and used to study the ensemble kinetic conversion of isopropanol over the surfaces, which showed a remarkable selectivity to form acetone, with minor propylene products appearing at elevated temperatures. These results in combination with inelastic neutron scattering measurements provide not only new insight into the selectivity and overall activity of the catalysts but also low frequency vibrational signatures of the adsorbed and reacted species. To compliment these measurements, pristine thin films of STO (100) were synthesized and used in combination with vibrational sum frequency generation spectroscopy to extract the absolute molecular orientation of the adsorbed molecules at the interface. It was found that the isopropanol assumes an orientation where the -CH group points towards the STO surface; this pre-reaction geometry offers an obvious pathway to produce acetone by abstracting the alpha-proton and, thus,more » provides a mechanistic explanation of selectivity at STO (100) surfaces. This new insight opens up pathways to explore and modify surfaces to tune the activity/selectivity though a molecular level understanding of the reactions at the surface.« less

Authors:
ORCiD logo [1];  [2]; ORCiD logo [1]; ORCiD logo [3];  [3]; ORCiD logo [4]; ORCiD logo [4]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Chemical Sciences Division
  2. The Ohio State Univ., Columbus, OH (United States). Dept. of Chemistry and Biochemistry
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Chemical and Engineering Materials Division, Neutron Sciences Directorate
  4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science & Technology Division
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1429202
Grant/Contract Number:
AC05-00OR22725
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
ACS Catalysis
Additional Journal Information:
Journal Volume: 7; Journal Issue: 12; Journal ID: ISSN 2155-5435
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; isopropyl alcohol; neutron spectroscopy; perovskite; SFG; strontium titanate

Citation Formats

Tan, Shuai, Grey, Matthew B., Kidder, Michelle, Cheng, Yongqiang, Daemen, Luke L., Lee, Dongkyu, Lee, Ho Nyung, Ma, Ying-zhong, Doughty, Benjamin L., and Lutterman, Daniel A. Insight into the Selectivity of Isopropanol Conversion at Strontium Titanate (100) Surfaces: A Combination Kinetic and Spectroscopic Study. United States: N. p., 2017. Web. doi:10.1021/acscatal.7b02417.
Tan, Shuai, Grey, Matthew B., Kidder, Michelle, Cheng, Yongqiang, Daemen, Luke L., Lee, Dongkyu, Lee, Ho Nyung, Ma, Ying-zhong, Doughty, Benjamin L., & Lutterman, Daniel A. Insight into the Selectivity of Isopropanol Conversion at Strontium Titanate (100) Surfaces: A Combination Kinetic and Spectroscopic Study. United States. doi:10.1021/acscatal.7b02417.
Tan, Shuai, Grey, Matthew B., Kidder, Michelle, Cheng, Yongqiang, Daemen, Luke L., Lee, Dongkyu, Lee, Ho Nyung, Ma, Ying-zhong, Doughty, Benjamin L., and Lutterman, Daniel A. Fri . "Insight into the Selectivity of Isopropanol Conversion at Strontium Titanate (100) Surfaces: A Combination Kinetic and Spectroscopic Study". United States. doi:10.1021/acscatal.7b02417.
@article{osti_1429202,
title = {Insight into the Selectivity of Isopropanol Conversion at Strontium Titanate (100) Surfaces: A Combination Kinetic and Spectroscopic Study},
author = {Tan, Shuai and Grey, Matthew B. and Kidder, Michelle and Cheng, Yongqiang and Daemen, Luke L. and Lee, Dongkyu and Lee, Ho Nyung and Ma, Ying-zhong and Doughty, Benjamin L. and Lutterman, Daniel A.},
abstractNote = {This work aims to better understand the role of interfacial molecular structure that governs selectivity and activity in heterogeneous catalytic reactions. To address this, a comprehensive study of isopropanol conversion over an archetypal perovskite material, strontium titanate (SrTiO3 or STO), was performed with an array of techniques sensitive to orthogonal aspects of the ensuing chemistry. Cubic-shape STO nanoparticles with only the (100) facet exposed were synthesized and used to study the ensemble kinetic conversion of isopropanol over the surfaces, which showed a remarkable selectivity to form acetone, with minor propylene products appearing at elevated temperatures. These results in combination with inelastic neutron scattering measurements provide not only new insight into the selectivity and overall activity of the catalysts but also low frequency vibrational signatures of the adsorbed and reacted species. To compliment these measurements, pristine thin films of STO (100) were synthesized and used in combination with vibrational sum frequency generation spectroscopy to extract the absolute molecular orientation of the adsorbed molecules at the interface. It was found that the isopropanol assumes an orientation where the -CH group points towards the STO surface; this pre-reaction geometry offers an obvious pathway to produce acetone by abstracting the alpha-proton and, thus, provides a mechanistic explanation of selectivity at STO (100) surfaces. This new insight opens up pathways to explore and modify surfaces to tune the activity/selectivity though a molecular level understanding of the reactions at the surface.},
doi = {10.1021/acscatal.7b02417},
journal = {ACS Catalysis},
number = 12,
volume = 7,
place = {United States},
year = {Fri Oct 13 00:00:00 EDT 2017},
month = {Fri Oct 13 00:00:00 EDT 2017}
}

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