Details
| Original language | English |
|---|---|
| Pages (from-to) | 5886-5899 |
| Number of pages | 14 |
| Journal | Catalysis Science and Technology |
| Volume | 8 |
| Issue number | 22 |
| Early online date | 8 Oct 2018 |
| Publication status | Published - 21 Nov 2018 |
Abstract
The photocatalytic decomposition of aqueous acetic acid into molecular hydrogen, carbon dioxide, and hydrocarbons employing platinized titania (Pt/TiO 2) as a photocatalyst has been studied. In order to investigate the detailed reaction mechanism, isotopic labelling experiments were performed by using solvents (H 2O and D 2O) and acetic acids (CH 3COOH, CD 3COOD, and CH 3COOD) with different isotopic compositions. The main reaction products resulting from the photocatalytic decomposition of aqueous acetic acid were determined quantitatively in the gas phase via quadrupole mass spectroscopy (QMS). Carbon dioxide, molecular hydrogen, molecular deuterium, and several isotopologues of methane were observed as the main reaction products. The evolution rates of all the main reaction products and their corresponding distribution were found to be strongly influenced by different isotopologues of both acetic acid and water. For instance, the reaction system Pt/TiO 2-CD 3COOD-D 2O yields approximately 2 times higher evolution rates for all main gaseous reaction products in comparison with the reaction system Pt/TiO 2-CH 3COOH-H 2O. Moreover, the data analysis from the isotopic labelling studies illustrates a high proton exchange reaction at both the carboxyl and the methyl group of acetic acid, which is further confirmed by 1H nuclear magnetic resonance (NMR) spectroscopy. For the reaction systems Pt/TiO 2-CD 3COOD-H 2O and Pt/TiO 2-CH 3COOH-D 2O, the NMR spectra demonstrated the transformation of CD 3COOD into CD 2HCOOD(H) and CH 3COOH into CH 2DCOOH(D), respectively. This means that during the photocatalytic decomposition of aqueous acetic acid, the protons participating in the formation of molecular hydrogen and methane originate from both acetic acid and water. However, the main source for the molecular hydrogen and methane evolution was found to be the solvent while acetic acid acts as a sacrificial reagent in the overall reaction.
ASJC Scopus subject areas
- Chemical Engineering(all)
- Catalysis
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In: Catalysis Science and Technology, Vol. 8, No. 22, 21.11.2018, p. 5886-5899.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Spectroscopic analysis of proton exchange during the photocatalytic decomposition of aqueous acetic acid
T2 - An isotopic study on the product distribution and reaction rate
AU - Hamid, Saher
AU - Dillert, Ralf
AU - Schneider, Jenny
AU - Bahnemann, Detlef W.
N1 - © The Royal Society of Chemistry 2018
PY - 2018/11/21
Y1 - 2018/11/21
N2 - The photocatalytic decomposition of aqueous acetic acid into molecular hydrogen, carbon dioxide, and hydrocarbons employing platinized titania (Pt/TiO 2) as a photocatalyst has been studied. In order to investigate the detailed reaction mechanism, isotopic labelling experiments were performed by using solvents (H 2O and D 2O) and acetic acids (CH 3COOH, CD 3COOD, and CH 3COOD) with different isotopic compositions. The main reaction products resulting from the photocatalytic decomposition of aqueous acetic acid were determined quantitatively in the gas phase via quadrupole mass spectroscopy (QMS). Carbon dioxide, molecular hydrogen, molecular deuterium, and several isotopologues of methane were observed as the main reaction products. The evolution rates of all the main reaction products and their corresponding distribution were found to be strongly influenced by different isotopologues of both acetic acid and water. For instance, the reaction system Pt/TiO 2-CD 3COOD-D 2O yields approximately 2 times higher evolution rates for all main gaseous reaction products in comparison with the reaction system Pt/TiO 2-CH 3COOH-H 2O. Moreover, the data analysis from the isotopic labelling studies illustrates a high proton exchange reaction at both the carboxyl and the methyl group of acetic acid, which is further confirmed by 1H nuclear magnetic resonance (NMR) spectroscopy. For the reaction systems Pt/TiO 2-CD 3COOD-H 2O and Pt/TiO 2-CH 3COOH-D 2O, the NMR spectra demonstrated the transformation of CD 3COOD into CD 2HCOOD(H) and CH 3COOH into CH 2DCOOH(D), respectively. This means that during the photocatalytic decomposition of aqueous acetic acid, the protons participating in the formation of molecular hydrogen and methane originate from both acetic acid and water. However, the main source for the molecular hydrogen and methane evolution was found to be the solvent while acetic acid acts as a sacrificial reagent in the overall reaction.
AB - The photocatalytic decomposition of aqueous acetic acid into molecular hydrogen, carbon dioxide, and hydrocarbons employing platinized titania (Pt/TiO 2) as a photocatalyst has been studied. In order to investigate the detailed reaction mechanism, isotopic labelling experiments were performed by using solvents (H 2O and D 2O) and acetic acids (CH 3COOH, CD 3COOD, and CH 3COOD) with different isotopic compositions. The main reaction products resulting from the photocatalytic decomposition of aqueous acetic acid were determined quantitatively in the gas phase via quadrupole mass spectroscopy (QMS). Carbon dioxide, molecular hydrogen, molecular deuterium, and several isotopologues of methane were observed as the main reaction products. The evolution rates of all the main reaction products and their corresponding distribution were found to be strongly influenced by different isotopologues of both acetic acid and water. For instance, the reaction system Pt/TiO 2-CD 3COOD-D 2O yields approximately 2 times higher evolution rates for all main gaseous reaction products in comparison with the reaction system Pt/TiO 2-CH 3COOH-H 2O. Moreover, the data analysis from the isotopic labelling studies illustrates a high proton exchange reaction at both the carboxyl and the methyl group of acetic acid, which is further confirmed by 1H nuclear magnetic resonance (NMR) spectroscopy. For the reaction systems Pt/TiO 2-CD 3COOD-H 2O and Pt/TiO 2-CH 3COOH-D 2O, the NMR spectra demonstrated the transformation of CD 3COOD into CD 2HCOOD(H) and CH 3COOH into CH 2DCOOH(D), respectively. This means that during the photocatalytic decomposition of aqueous acetic acid, the protons participating in the formation of molecular hydrogen and methane originate from both acetic acid and water. However, the main source for the molecular hydrogen and methane evolution was found to be the solvent while acetic acid acts as a sacrificial reagent in the overall reaction.
UR - http://www.scopus.com/inward/record.url?scp=85056624299&partnerID=8YFLogxK
U2 - 10.1039/c8cy01815d
DO - 10.1039/c8cy01815d
M3 - Article
VL - 8
SP - 5886
EP - 5899
JO - Catalysis Science and Technology
JF - Catalysis Science and Technology
SN - 2044-4753
IS - 22
ER -