A study of the reactions of ethanol on CeO2 and Pd/CeO2 by steady state reactions, temperature programmed desorption, and in situ FT-IR

A Yee, S J Morrison, Hicham Idriss

Research output: Contribution to journalArticle

243 Citations (Scopus)

Abstract

The reaction of ethanol on unreduced and H-2-reduced CeO2 and 1 wt% Pd/CeO2 has been investigated by steady state reactions, temperature programmed desorption (TPD), and in situ Fourier transform infrared (FT-IR) spectroscopy. Steady state reactions have shown a zero reaction order dependency for diatomic oxygen at and above 20%, whilst the addition of Pd to CeO2 decreases the apparent activation energy of the reaction from 75 kJ mol(-1) on CeO2 alone to 40 kJ mol(-1) (Pd/CeO2). TPD experiments following ethanol adsorption on both CeO2 and Pd/CeO2 have shown desorption profiles corresponding to unreacted ethanol and various reaction and decomposition products (acetaldehyde, acetone, CO, CO2, and methane). Ethanol conversion to reaction products was increased by the addition of Pd, from 15 and 30% on CeO2 and H-2-reduced CeO2, to 71 and 63% on Pd/CeO2 and H-2-reduced Pd/CeO2, respectively. Acetaldehyde desorbed in two temperature domains on CeO2, and desorbed as one peak only on Hz-reduced CeO2(555 K), Pd/CeO2 (395 K), and H-2-reduced Pd/CeO2 (410 K). Desorption of acetone was observed on all surfaces; however, the desorption temperatures were considerably lower on Pd/CeO2 than on CeO2, suggesting that the formation of acetone on Pd/CeO2 occurs from a different reaction pathway from that of CeO2. Benzene formation was detected only on Pd/CeO2 catalysts, with the H-2-reduced Pd/CeO2 catalyst decreasing benzene formation to almost negligible amounts. FT-IR results have shown that ethanol adsorbs dissociatively at room temperature to form adsorbed ethoxide species on all surfaces studied. Acetate species (nu(as)(OCO) 1572 cm(-1) and nu(s)(OCO) 1424 cm(-1)) were detected on the unreduced CeO2 surface at room temperature. In contrast, H-2-reduced CeO2, as well as "as prepared'' Pd/CeO2, did not show evidence of acetates at room temperature. The decrease of the XPS O(1s)/Ce(3d) ratio in the case of Pd/CeO2 (1.76) together with the absence of acetate formation may indicate partial reduction of the CeO2 support upon the addition of Pd. Adsorbed acetaldehyde was detected on Pd/CeO2 (1711 cm(-1)) and H-2-reduced Pd/CeO2 (1704 cm(-1)) upon heating to 373 and 423 K, respectively. Adsorbed crotonaldehyde (nu(CO) ca. 1651 and nu(C=C) ca. 1634 cm(-1)), from the beta-aldolisation of two acetaldehyde molecules, was observed on both unreduced and high temperature reduced Pd/CeO2 at 473 K. Carbonates were the remaining species at 625 K and above. (C) 1999 Academic Press.

Original languageEnglish
Pages (from-to)279-295
Number of pages17
JournalJournal of Catalysis
Volume186
Issue number2
Publication statusPublished - 10 Sep 1999

Keywords

  • CARBON BOND FORMATION
  • SPECTROSCOPIC IDENTIFICATION
  • INFRARED-SPECTROSCOPY
  • 3-WAY CATALYSTS
  • SINGLE-CRYSTAL
  • OXYGEN STORAGE
  • METAL-OXIDES
  • FORMIC-ACID
  • ZINC-OXIDE
  • METHANOL

Cite this

A study of the reactions of ethanol on CeO2 and Pd/CeO2 by steady state reactions, temperature programmed desorption, and in situ FT-IR. / Yee, A ; Morrison, S J ; Idriss, Hicham.

In: Journal of Catalysis, Vol. 186, No. 2, 10.09.1999, p. 279-295.

Research output: Contribution to journalArticle

@article{830ce765ea7447a8a8d98f861859bd35,
title = "A study of the reactions of ethanol on CeO2 and Pd/CeO2 by steady state reactions, temperature programmed desorption, and in situ FT-IR",
abstract = "The reaction of ethanol on unreduced and H-2-reduced CeO2 and 1 wt{\%} Pd/CeO2 has been investigated by steady state reactions, temperature programmed desorption (TPD), and in situ Fourier transform infrared (FT-IR) spectroscopy. Steady state reactions have shown a zero reaction order dependency for diatomic oxygen at and above 20{\%}, whilst the addition of Pd to CeO2 decreases the apparent activation energy of the reaction from 75 kJ mol(-1) on CeO2 alone to 40 kJ mol(-1) (Pd/CeO2). TPD experiments following ethanol adsorption on both CeO2 and Pd/CeO2 have shown desorption profiles corresponding to unreacted ethanol and various reaction and decomposition products (acetaldehyde, acetone, CO, CO2, and methane). Ethanol conversion to reaction products was increased by the addition of Pd, from 15 and 30{\%} on CeO2 and H-2-reduced CeO2, to 71 and 63{\%} on Pd/CeO2 and H-2-reduced Pd/CeO2, respectively. Acetaldehyde desorbed in two temperature domains on CeO2, and desorbed as one peak only on Hz-reduced CeO2(555 K), Pd/CeO2 (395 K), and H-2-reduced Pd/CeO2 (410 K). Desorption of acetone was observed on all surfaces; however, the desorption temperatures were considerably lower on Pd/CeO2 than on CeO2, suggesting that the formation of acetone on Pd/CeO2 occurs from a different reaction pathway from that of CeO2. Benzene formation was detected only on Pd/CeO2 catalysts, with the H-2-reduced Pd/CeO2 catalyst decreasing benzene formation to almost negligible amounts. FT-IR results have shown that ethanol adsorbs dissociatively at room temperature to form adsorbed ethoxide species on all surfaces studied. Acetate species (nu(as)(OCO) 1572 cm(-1) and nu(s)(OCO) 1424 cm(-1)) were detected on the unreduced CeO2 surface at room temperature. In contrast, H-2-reduced CeO2, as well as {"}as prepared'' Pd/CeO2, did not show evidence of acetates at room temperature. The decrease of the XPS O(1s)/Ce(3d) ratio in the case of Pd/CeO2 (1.76) together with the absence of acetate formation may indicate partial reduction of the CeO2 support upon the addition of Pd. Adsorbed acetaldehyde was detected on Pd/CeO2 (1711 cm(-1)) and H-2-reduced Pd/CeO2 (1704 cm(-1)) upon heating to 373 and 423 K, respectively. Adsorbed crotonaldehyde (nu(CO) ca. 1651 and nu(C=C) ca. 1634 cm(-1)), from the beta-aldolisation of two acetaldehyde molecules, was observed on both unreduced and high temperature reduced Pd/CeO2 at 473 K. Carbonates were the remaining species at 625 K and above. (C) 1999 Academic Press.",
keywords = "CARBON BOND FORMATION, SPECTROSCOPIC IDENTIFICATION, INFRARED-SPECTROSCOPY, 3-WAY CATALYSTS, SINGLE-CRYSTAL, OXYGEN STORAGE, METAL-OXIDES, FORMIC-ACID, ZINC-OXIDE, METHANOL",
author = "A Yee and Morrison, {S J} and Hicham Idriss",
year = "1999",
month = "9",
day = "10",
language = "English",
volume = "186",
pages = "279--295",
journal = "Journal of Catalysis",
issn = "0021-9517",
publisher = "ACADEMIC PRESS INC ELSEVIER SCIENCE",
number = "2",

}

TY - JOUR

T1 - A study of the reactions of ethanol on CeO2 and Pd/CeO2 by steady state reactions, temperature programmed desorption, and in situ FT-IR

AU - Yee, A

AU - Morrison, S J

AU - Idriss, Hicham

PY - 1999/9/10

Y1 - 1999/9/10

N2 - The reaction of ethanol on unreduced and H-2-reduced CeO2 and 1 wt% Pd/CeO2 has been investigated by steady state reactions, temperature programmed desorption (TPD), and in situ Fourier transform infrared (FT-IR) spectroscopy. Steady state reactions have shown a zero reaction order dependency for diatomic oxygen at and above 20%, whilst the addition of Pd to CeO2 decreases the apparent activation energy of the reaction from 75 kJ mol(-1) on CeO2 alone to 40 kJ mol(-1) (Pd/CeO2). TPD experiments following ethanol adsorption on both CeO2 and Pd/CeO2 have shown desorption profiles corresponding to unreacted ethanol and various reaction and decomposition products (acetaldehyde, acetone, CO, CO2, and methane). Ethanol conversion to reaction products was increased by the addition of Pd, from 15 and 30% on CeO2 and H-2-reduced CeO2, to 71 and 63% on Pd/CeO2 and H-2-reduced Pd/CeO2, respectively. Acetaldehyde desorbed in two temperature domains on CeO2, and desorbed as one peak only on Hz-reduced CeO2(555 K), Pd/CeO2 (395 K), and H-2-reduced Pd/CeO2 (410 K). Desorption of acetone was observed on all surfaces; however, the desorption temperatures were considerably lower on Pd/CeO2 than on CeO2, suggesting that the formation of acetone on Pd/CeO2 occurs from a different reaction pathway from that of CeO2. Benzene formation was detected only on Pd/CeO2 catalysts, with the H-2-reduced Pd/CeO2 catalyst decreasing benzene formation to almost negligible amounts. FT-IR results have shown that ethanol adsorbs dissociatively at room temperature to form adsorbed ethoxide species on all surfaces studied. Acetate species (nu(as)(OCO) 1572 cm(-1) and nu(s)(OCO) 1424 cm(-1)) were detected on the unreduced CeO2 surface at room temperature. In contrast, H-2-reduced CeO2, as well as "as prepared'' Pd/CeO2, did not show evidence of acetates at room temperature. The decrease of the XPS O(1s)/Ce(3d) ratio in the case of Pd/CeO2 (1.76) together with the absence of acetate formation may indicate partial reduction of the CeO2 support upon the addition of Pd. Adsorbed acetaldehyde was detected on Pd/CeO2 (1711 cm(-1)) and H-2-reduced Pd/CeO2 (1704 cm(-1)) upon heating to 373 and 423 K, respectively. Adsorbed crotonaldehyde (nu(CO) ca. 1651 and nu(C=C) ca. 1634 cm(-1)), from the beta-aldolisation of two acetaldehyde molecules, was observed on both unreduced and high temperature reduced Pd/CeO2 at 473 K. Carbonates were the remaining species at 625 K and above. (C) 1999 Academic Press.

AB - The reaction of ethanol on unreduced and H-2-reduced CeO2 and 1 wt% Pd/CeO2 has been investigated by steady state reactions, temperature programmed desorption (TPD), and in situ Fourier transform infrared (FT-IR) spectroscopy. Steady state reactions have shown a zero reaction order dependency for diatomic oxygen at and above 20%, whilst the addition of Pd to CeO2 decreases the apparent activation energy of the reaction from 75 kJ mol(-1) on CeO2 alone to 40 kJ mol(-1) (Pd/CeO2). TPD experiments following ethanol adsorption on both CeO2 and Pd/CeO2 have shown desorption profiles corresponding to unreacted ethanol and various reaction and decomposition products (acetaldehyde, acetone, CO, CO2, and methane). Ethanol conversion to reaction products was increased by the addition of Pd, from 15 and 30% on CeO2 and H-2-reduced CeO2, to 71 and 63% on Pd/CeO2 and H-2-reduced Pd/CeO2, respectively. Acetaldehyde desorbed in two temperature domains on CeO2, and desorbed as one peak only on Hz-reduced CeO2(555 K), Pd/CeO2 (395 K), and H-2-reduced Pd/CeO2 (410 K). Desorption of acetone was observed on all surfaces; however, the desorption temperatures were considerably lower on Pd/CeO2 than on CeO2, suggesting that the formation of acetone on Pd/CeO2 occurs from a different reaction pathway from that of CeO2. Benzene formation was detected only on Pd/CeO2 catalysts, with the H-2-reduced Pd/CeO2 catalyst decreasing benzene formation to almost negligible amounts. FT-IR results have shown that ethanol adsorbs dissociatively at room temperature to form adsorbed ethoxide species on all surfaces studied. Acetate species (nu(as)(OCO) 1572 cm(-1) and nu(s)(OCO) 1424 cm(-1)) were detected on the unreduced CeO2 surface at room temperature. In contrast, H-2-reduced CeO2, as well as "as prepared'' Pd/CeO2, did not show evidence of acetates at room temperature. The decrease of the XPS O(1s)/Ce(3d) ratio in the case of Pd/CeO2 (1.76) together with the absence of acetate formation may indicate partial reduction of the CeO2 support upon the addition of Pd. Adsorbed acetaldehyde was detected on Pd/CeO2 (1711 cm(-1)) and H-2-reduced Pd/CeO2 (1704 cm(-1)) upon heating to 373 and 423 K, respectively. Adsorbed crotonaldehyde (nu(CO) ca. 1651 and nu(C=C) ca. 1634 cm(-1)), from the beta-aldolisation of two acetaldehyde molecules, was observed on both unreduced and high temperature reduced Pd/CeO2 at 473 K. Carbonates were the remaining species at 625 K and above. (C) 1999 Academic Press.

KW - CARBON BOND FORMATION

KW - SPECTROSCOPIC IDENTIFICATION

KW - INFRARED-SPECTROSCOPY

KW - 3-WAY CATALYSTS

KW - SINGLE-CRYSTAL

KW - OXYGEN STORAGE

KW - METAL-OXIDES

KW - FORMIC-ACID

KW - ZINC-OXIDE

KW - METHANOL

M3 - Article

VL - 186

SP - 279

EP - 295

JO - Journal of Catalysis

JF - Journal of Catalysis

SN - 0021-9517

IS - 2

ER -