ChemInform Abstract: OXIDATION STATES OF COPPER DURING REDUCTION OF CUPRIC OXIDE IN METHANOL CATALYSTS

Himelfarb, P.B.; Wawner, F. E.; Bieser, A.; VINES, S. N.

doi:10.1002/chin.198351028

Cited by 7 publications

(11 citation statements)

References 1 publication

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“…The reduction process follows a sigmoidal curve of reduction rate versus reduction degree [157][158][159][160][161][162][163][164][165]. This could be explained by an induction phenomenon, by difficulties in nucleation [165,166] or by autocatalysis due to the Cu crystallites formed [167].…”

Section: Other Catalystsmentioning

confidence: 99%

“…It has been reported that reduction of CuO in a binary catalyst is retarded compared with pure CuO [62,73,157,162,164,168,169], whereas it is accelerated in ternary catalysts [169]. CO reduces CuO faster than H 2 , especially in the final stages of the reduction where it is believed that the presence of hydroxyl groups on the surface of the catalyst inhibits the reduction by H 2 [167,170].…”

Section: Other Catalystsmentioning

confidence: 99%

“…The reduction of CuO to Cu was found by some authors [164][165][166]171] to go through Cu 2 O, whereas others [162] have not identified this intermediate stage.…”

Section: Other Catalystsmentioning

confidence: 99%

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Methanol Synthesis

Hansen¹,

Nielsen²

2008

Handbook of Heterogeneous Catalysis

133

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The sections in this article are Introduction Thermodynamics Methanol Synthesis Catalysts Introduction Zn O / Cr 2 O 3 Catalyst Copper‐Based Catalysts Cu / Zn O + Element ( Al , Cr , … ) Promotion of Cu / Zn O / MOx Catalysts Cu / Zr O 2 Other Cu , Cu / Me , Cu / Me Ox Catalysts Pd ‐Based Catalysts Sulfide Catalysts Other Catalysts Activation of Cu / Zn Catalyst Activity as a Function of the Nature of Copper‐Based Catalysts Catalyst Deactivation Sintering Sulfur Poisoning Other Poisons By‐Product Formation Reaction Mechanism(s) and Active Sites Cu + in a Zn O Matrix as the Active Center The S chottky Junction Theory Partly Oxidized Copper Independent of Support as Active Sites Metallic Copper in Dynamic Interaction with the Support Cu –Zinc Surface Alloy Model Water Gas Shift Reaction Kinetics Reaction Rate Equations Diffusion Restrictions Kinetics in Slurry Phase Methanol Synthesis Methanol Synthesis Technology Synthesis Gas Preparation Natural Gas Reforming Adiabatic Pre‐Reforming Tubular, Fired Reforming Autothermal Reforming and Oxygen‐Fired Secondary Reforming Gasification of Heavy Oil, Coal or Biomass Coproduction in Ammonia Plants and Use of Off‐gases Economics of Synthesis Gas Preparation Reactor Systems and Synthesis Loop Layout Slurry Phase Reactor Types Methanol Purification Concepts Circumventing the Equilibrium Limitations Other Methanol Synthesis Routes and Technologies Methanol Synthesis by Methane Activation Conclusion

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Section: Other Catalystsmentioning

confidence: 99%

Section: Other Catalystsmentioning

confidence: 99%

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Methanol Synthesis

Hansen¹,

Nielsen²

2008

Handbook of Heterogeneous Catalysis

133

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“…Fierro et al [11] studied the reduction of CuO/ZnO with different Cu/Zn ratios and found a promoting effect of ZnO on the reducibility of CuO. Structural investigations of the copper phase under reduction conditions based on XRD [12,13] and, moreover, recent time-resolved XANES [14] indicate that Cu 2 O (Cu + ) phase was formed as a transient species in the reduction of Cu 2+ to Cu 0 although no activity was attributed to it. Only one paper [15] reported Cu 2 O as active species in the steam reforming of methanol over CuO/ZrO 2 catalysts.…”

Section: Introductionmentioning

confidence: 97%

Production of hydrogen from methanol over Cu/ZnO and Cu/ZnO/Al2O3 catalysts prepared by homogeneous precipitation: Steam reforming and oxidative steam reforming

Shishido

Yamamoto

Morioka

et al. 2007

Journal of Molecular Catalysis A: Chemical

112

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Two series of Cu/ZnO and Cu/ZnO/Al 2 O 3 catalysts with varying Cu/Zn ratio have been prepared by the homogeneous precipitation (hp) method using urea hydrolysis. Steam reforming and oxidative steam reforming of methanol were performed using the hp-Cu/Zn-based catalysts for catalytic production of hydrogen. The hp-Cu/ZnO/Al 2 O 3 catalyst showed a higher activity than the hp-Cu/ZnO catalysts. In both cases, the catalytic activity was well correlated with the surface area of Cu metal, and the maximum activity was obtained on the hp-Cu/ZnO/Al 2 O 3 catalyst with the Cu/Zn ratio of 1/1. Although a large amount of Cu + was detected on the surface of the Cu/Zn-based catalysts after the reduction at 260 • C, no obvious correlation was observed between the activity and the surface amount of Cu + . The hp-Cu/ZnO/Al 2 O 3 catalyst showed a high and stable activity not only for steam reforming but also for oxidative steam reforming of methanol, and the latter reaction effectively produced H 2 with a low CO selectivity at a low temperature around 200 • C. It was confirmed by the temperature-programmed desorption experiments that CH 3 OH was first dehydrogenated to HCHO, which then underwent a nucleophilic attack of H 2 O to form HCOOH, followed by the decomposition to H 2 and CO 2 on the hp-Cu/Zn-based catalysts.

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“…Accordingly, the stabilization of Cu 2 O is expected under low hydrogen pressure [42]. Therefore, the heterobimetallic copper-lanthanide oxides first H 2 -TPR unresolved profiles can be attributed to the evolution of copper oxidation state along the temperature-programmed reduction measurements that at very low hydrogen partial pressure stabilize as Cu + .…”

Section: H 2 -Tpr Studiesmentioning

confidence: 95%