An EXAFS study of Cu/ZnO and Cu/ZnO-Al2O3 methanol synthesis catalysts

Arunarkavalli, T.; Rao, C. N. R.

doi:10.1007/bf00769298

Cited by 10 publications

(4 citation statements)

References 13 publications

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“…We have carried out considerable work on the active species (Co/Ni-Mo-S) in hydrodesulphurization catalysts (figure 7). A study of methanol synthesis catalysts has shown the unusual nature of the copper species on the surface (Arunarkavalli et a! 1993).…”

Section: Catalystsmentioning

confidence: 99%

Four decades of research in solid state chemistry

Rao

1993

Bull. Mater. Sci.

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Section: Catalystsmentioning

confidence: 99%

Four decades of research in solid state chemistry

Rao

1993

Bull. Mater. Sci.

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“…The relative amounts were not reported, but the average number of oxygen neighbors around a Cu atom was highest in the catalyst with the lowest Cu loading, most likely indicating the highest fraction of oxidized Cu in that sample. Another in-situ study by this group also detected Cu in all three oxidation states [20], but sample wafers contained a binder that may not be completely removed during reduction and may have protected some CuO from contact with H 2 .…”

Section: Introductionmentioning

confidence: 97%

New insights into methanol synthesis catalysts from X-ray absorption spectroscopy

Meitzner¹,

Iglesia

1999

Catalysis Today

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X-ray absorption spectroscopic studies from several different groups provide a consistent structural picture of methanol synthesis catalysts. Copper metal is the principal Cu species detected in all in-situ XAS studies. A small amount of Cu(II) persisted in many samples reduced below 600 K, but it appears to be catalytically irrelevant. Cu(I) was not detected in any of the in-situ XAS studies. The Zn structure did not change in response to chemical treatments in any of the ZnO-containing methanol synthesis catalysts.We conclude that the slow approach to steady-state rate of methanol synthesis from CO/H 2 mixtures cannot result from changes in the Cu metal component of Cu/SiO 2 catalysts. By eliminating this possibility, we provide indirect evidence for the proposal that initial induction periods reflect slow changes in the surface of the SiO 2 or ZnO component in the catalysts. A bifunctional mechanism involving the formation of formate from CO on support hydroxyl groups would increase methanol synthesis rates as OH groups are formed by hydrolysis of Si-O bonds using the H 2 O formed in slow methanation side reactions. The bifunctional mechanism is not required for the synthesis of methanol from CO 2 -containing mixtures, because formate can form on Cu directly from CO 2 and H 2 .

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“…The slope of this straight line is equal to the isokinetic temperature and was found to be equal to 327 K which is higher than the average experimental temperature (309 K). This means that the reaction is enthalpy controlled [23,24]. The linearity of the isokinetic relationship supports the claim that a single mechanism which involves free radicals, operates for all catalyzed reactions under investigation.…”

Section: Discussionmentioning

confidence: 52%

“…A plot of enthalpy versus entropy change (isokinetic relationship) [23] is linear ( Figure 10). The slope of this straight line is equal to the isokinetic temperature and was found to be equal to 327 K which is higher than the average experimental temperature (309 K).…”

Section: Discussionmentioning

confidence: 99%

Enhancement of the catalytic activity of [Cu2(TS)(OH)2(OAc)] using superconductor cuprate sample

Hamada

El-Shafai

El‐Asmy

2006

Transition Met Chem

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A superconducting sample (Nd 0.1 Y 0.9 Ba 2 Cu 3 O 7-d ) has been tried as a catalyst for H 2 O 2 decomposition. All parameters affecting the reaction rate (concentration of H 2 O 2 , weight of catalyst, temperature and pH) were studied and the optimum conditions were evaluated. A mixture of the superconducting cuprate with [Cu 2 (TS)(OH)(OAc)] using different percentages of the sample has been prepared and tried kinetically under the same mentioned conditions. An attempt was made to increase the activity of the complex. The data show that the cuprate sample alone was found to be almost inactive when compared with that of the mixture. The catalytic mechanism in the absence and presence of the complex was suggested.

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An EXAFS study of Cu/ZnO and Cu/ZnO-Al2O3 methanol synthesis catalysts

Cited by 10 publications

References 13 publications

Four decades of research in solid state chemistry

Four decades of research in solid state chemistry

New insights into methanol synthesis catalysts from X-ray absorption spectroscopy

Enhancement of the catalytic activity of [Cu2(TS)(OH)2(OAc)] using superconductor cuprate sample

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