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Title: Photothermal heterogeneous oxidation of ethanol over Pt/TiO{sub 2}

Abstract

Photothermal catalytic oxidation of ethanol over TiO{sub 2} and Pt/TiO{sub 2} has been investigated. Platinum was deposited on the titania using both photoreduction and adsorption of the PtCl{sub 6}{sup 2{minus}} anion. The nominal weight loadings of Pt were less than 1 wt%. Thermal contributions to ethanol oxidation over Pt could be distinguished from photo-contributions to ethanol oxidation over TiO{sub 2} by comparing illuminated and dark reactions under the same conditions. A significant photothermal synergistic effect was seen for Pt/TiO{sub 2} catalysts. The activity for complete oxidation to CO{sub 2} is much greater than the contribution from photo-oxidation over TiO{sub 2} plus thermal oxidation over Pt. Experiments were conducted to investigate the mechanistic nature of the synergistic effect. The synergistic effect was found to be sensitive to preparation conditions, with photoreduced catalysts having higher activities compared to thermally reduced catalysts prepared by adsorption of the PtCl{sub 6}{sup 2{minus}} anion. The differences between the photo and thermally reduced Pt/TiO{sub 2} are attributed to differing extents of etching of the TiO{sub 2} surface by the acidic solution of chloroplatinic acid. An experiment with layered beds of Pt/TiO{sub 2} and TiO{sub 2} showed that adding unetched TiO{sub 2} to etched Pt/TiO{sub 2} could improvemore » CO{sub 2} production. The photothermal synergistic enhancement of CO{sub 2} production appears to be caused primarily by gas phase transport of intermediates between the two catalyst phases in a mixed series-parallel kinetic pathway. Increased levels of acetaldehyde produced by photo-oxidation over TiO{sub 2} can lead to CO{sub 2} production by thermal reaction of the acetaldehyde over Pt.« less

Authors:
;  [1]
  1. Univ. of New Mexico, Albuquerque, NM (United States)
Publication Date:
OSTI Identifier:
289437
Resource Type:
Journal Article
Journal Name:
Journal of Catalysis
Additional Journal Information:
Journal Volume: 179; Journal Issue: 2; Other Information: PBD: 25 Oct 1998
Country of Publication:
United States
Language:
English
Subject:
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION; ETHANOL; OXIDATION; PHOTOLYSIS; TITANIUM OXIDES; PLATINUM; CATALYTIC EFFECTS; CHEMICAL PREPARATION; CATALYSTS; CARBON DIOXIDE; ACETALDEHYDE

Citation Formats

Kennedy, III, J C, and Datye, A K. Photothermal heterogeneous oxidation of ethanol over Pt/TiO{sub 2}. United States: N. p., 1998. Web. doi:10.1006/jcat.1998.2242.
Kennedy, III, J C, & Datye, A K. Photothermal heterogeneous oxidation of ethanol over Pt/TiO{sub 2}. United States. doi:10.1006/jcat.1998.2242.
Kennedy, III, J C, and Datye, A K. Sun . "Photothermal heterogeneous oxidation of ethanol over Pt/TiO{sub 2}". United States. doi:10.1006/jcat.1998.2242.
@article{osti_289437,
title = {Photothermal heterogeneous oxidation of ethanol over Pt/TiO{sub 2}},
author = {Kennedy, III, J C and Datye, A K},
abstractNote = {Photothermal catalytic oxidation of ethanol over TiO{sub 2} and Pt/TiO{sub 2} has been investigated. Platinum was deposited on the titania using both photoreduction and adsorption of the PtCl{sub 6}{sup 2{minus}} anion. The nominal weight loadings of Pt were less than 1 wt%. Thermal contributions to ethanol oxidation over Pt could be distinguished from photo-contributions to ethanol oxidation over TiO{sub 2} by comparing illuminated and dark reactions under the same conditions. A significant photothermal synergistic effect was seen for Pt/TiO{sub 2} catalysts. The activity for complete oxidation to CO{sub 2} is much greater than the contribution from photo-oxidation over TiO{sub 2} plus thermal oxidation over Pt. Experiments were conducted to investigate the mechanistic nature of the synergistic effect. The synergistic effect was found to be sensitive to preparation conditions, with photoreduced catalysts having higher activities compared to thermally reduced catalysts prepared by adsorption of the PtCl{sub 6}{sup 2{minus}} anion. The differences between the photo and thermally reduced Pt/TiO{sub 2} are attributed to differing extents of etching of the TiO{sub 2} surface by the acidic solution of chloroplatinic acid. An experiment with layered beds of Pt/TiO{sub 2} and TiO{sub 2} showed that adding unetched TiO{sub 2} to etched Pt/TiO{sub 2} could improve CO{sub 2} production. The photothermal synergistic enhancement of CO{sub 2} production appears to be caused primarily by gas phase transport of intermediates between the two catalyst phases in a mixed series-parallel kinetic pathway. Increased levels of acetaldehyde produced by photo-oxidation over TiO{sub 2} can lead to CO{sub 2} production by thermal reaction of the acetaldehyde over Pt.},
doi = {10.1006/jcat.1998.2242},
journal = {Journal of Catalysis},
number = 2,
volume = 179,
place = {United States},
year = {1998},
month = {10}
}