The importance of water in the mechanism of methanol decomposition on ZnO

Chadwick, David; Zheng, K.

doi:10.1007/bf00769295

Cited by 29 publications

(16 citation statements)

References 20 publications

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“…and CO selectivity as a function of S/M ratio under the reaction conditions of GHSV = 28,690 h −1 and reaction temperature = 420 • C. Some researchers suggested that water and methanol compete for the same adsorption sites on ZnO [56]. Methanol is easily adsorbed onto the surface of ZnO to form methoxy species, which decompose into CO and H 2 eventually in the absence of water.…”

Section: Effect Of Steam To Methanol Ratiomentioning

confidence: 99%

High-temperature steam reforming of methanol over ZnO–Al2O3 catalysts

Yang

Chen

2011

Applied Catalysis B: Environmental

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Section: Effect Of Steam To Methanol Ratiomentioning

confidence: 99%

High-temperature steam reforming of methanol over ZnO–Al2O3 catalysts

Yang

Chen

2011

Applied Catalysis B: Environmental

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“…In 1923 they discovered that ZnO would convert CO/H 2 mixtures not to hydrocarbons but to CH 3 OH [6 and references therein]. Consequently much of the research that has been conducted on ZnO has focused on trying to elucidate the reaction pathway by which CO and H 2 are adsorbed on ZnO and transformed to CH 3 OH [7][8][9][10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

“…Several authors have done this [7][8][9][10][11][12][13][14]. Having first characterized the vibrational spectrum of a formate species on ZnO by adsorbing HCO 2 H on to the ZnO at 473 K and having shown that it was formed by CO 2 /H 2 co-adsorption at 473 K and not by CO/H 2 O co-adsorption at 473 K [7], Tamaru and coworkers showed that the same formate species was formed by adsorbing CH 3 OH on the ZnO at 473 K [8].…”

Section: Introductionmentioning

confidence: 99%

“…Chadwick and Zheng [12], using TPD virtually duplicated Bowker and co-workers' data [9]. Having dosed CH 3 OH on to the ZnO, on temperature programming they found two peaks of H 2 and CO at 580 and 610 K. They also found a smaller CO 2 peak ($1/ 17 th of the CO peak) at 595 K. Chadwick and Zheng found that pre-adsorption of H 2 O to a coverage of 1.7 Â 10 14 molecule cm )2 prior to dosing CH 3 OH, or coadsorption of H 2 O with CH 3 OH followed by temperature programming, increased the amount of CO 2 desorbed so that the CO 2 :CO ratio was increased from 1:17 to 2:1.…”

Section: Introductionmentioning

confidence: 99%

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On the mechanism of methanol synthesis and the water-gas shift reaction on ZnO

2006

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Zinc oxide catalyses both methanol synthesis and the forward and 'everse water-gas shift reaction (f-and r-WGSR). Copper also catalyses both reactions, but at lower temperatures than ZnO. Presently the combination of Cu and ZnO stabilized by Al 2 O 3 is the preferred catalyst for methanol synthesis and for the f-and r-WGSR. On Cu, the mechanism of methanol synthesis is by hydrogenation of an adsorbed bidentate formate [1] (the most stable adsorbed species in methanol synthesis), while the f-and r-WGSR proceeds by a redox mechanism. The f-WGSR proceeds by H 2 O oxidizing the Cu and CO, reducing the adsorbed oxide and the r-WGSR proceeds by CO 2 oxidising the Cu and H 2 , reducing it [2][3][4][5]. Here we show that the mechanisms of both reactions are subtly different on ZnO. While methanol is shown to be formed on ZnO through a formate intermediate, it is a monodentate formate species which is the intermediate; the f-and r-WGS reactions also proceed through a formate -a bidentate formate -in sharp contrast to the mechanism on Cu.

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“…The worse dispersion of platinum on the large crystal size of ZnO-R impelled the aggregation of platinum on the surface and depressed the rate of decomposition of acetaldehyde. Contrarily, the large crystal size of the zinc oxide-supported catalyst provided an adsorption site for water [28] to promote the steam reforming of acetaldehyde. As the particle size of the platinum catalyst decreased, the activity on the decomposition of acetaldehyde would be increased and shifted to a lower temperature.…”

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confidence: 99%

Surface Area Effect of Zinc Oxide for Steam Reforming of Ethanol over Supported-Platinum Catalysts

Chiou

Wang

et al. 2012

e-J. Surf. Sci. Nanotechnol.

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The effect of surface area over the ZnO-supported platinum catalysts on the catalytic performance of steam reforming of ethanol (SRE) has been studied. Various surface area of ZnO is prepared through two routes: reflux (assigned as ZnO-R), thermal decomposition under air (assigned as ZnO-A) and under N2 (assigned as ZnO-N). Also, the commercial ZnO (assigned as ZnO-C) is chosen as reference. Four Pt/ZnO catalysts (3 wt% loading of Pt) are prepared by incipient wetness impregnation (assigned as Pt-R, Pt-A, Pt-N and Pt-C, respectively). The BET measurement shows that the ZnO-A (89 m 2 ·g −1 ) support possesses a higher surface area than the ZnO-R (1.3 m 2 ·g −1 ). The catalytic activity on the SRE reaction is evaluated in a fixed-bed reactor under 22,000 h −1 GHSV and H2O/EtOH molar ratio of 13. The results show that total ethanol conversion is observed at 225• C and 400• C over the Pt-A and Pt-R catalysts, respectively. When the temperature exceeds 350• C, acetaldehyde decomposition and acetaldehyde steam reforming are competitive on the platinum catalysts to promote H2 production. The small particle size catalyst of Pt-A favors the decomposition of acetaldehyde to produce CH4 and CO, and the large particle size catalyst of Pt-R favors the steam reforming of acetaldehyde to produce CH4 and CO2.

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The importance of water in the mechanism of methanol decomposition on ZnO

Cited by 29 publications

References 20 publications

High-temperature steam reforming of methanol over ZnO–Al2O3 catalysts

High-temperature steam reforming of methanol over ZnO–Al2O3 catalysts

On the mechanism of methanol synthesis and the water-gas shift reaction on ZnO

Surface Area Effect of Zinc Oxide for Steam Reforming of Ethanol over Supported-Platinum Catalysts

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