EXAFS study of Cu$z.sbnd;ZnO/Al2O3 catalysts for the low-temperature CO shift reaction

Vlaic, G.; Bart, J. C. J.; Cavigiolo, W.; Pianzola, B; Mobilio, Settimio

doi:10.1016/0021-9517(85)90302-1

Cited by 16 publications

(11 citation statements)

References 28 publications

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Section: –1989supporting

confidence: 90%

“…From the point of speciation, however, (from XRD where Bragg peaks are visible, and EXAFS from where they are not), the two systems were found to be essentially equivalent. Both are composed of CuO and zinc oxide post calcination, with no indication of any other phases being present, in accordance with the ex situ studies of Mobilio et al 69,71 The coprecipitated samples, however, were found to behave very differently when they were reduced (Figure 12). In this case, the local structure of the reduced, metallic, copper phase was shown, up to a point, to be a reversible function of temperature.…”

Section: −1989supporting

confidence: 88%

“…In both these cases, however, one must consider this limit as being, even then, no more than a few percent. Five years later, a further study from the same group appeared, which, upon the basis of improved data sets and more quantitative assessment of the EXAFS, came to essentially the same conclusions.…”

Section: –1989mentioning

confidence: 76%

“…However, these conclusions were in opposition to some of the experiments (vide supra) that used methods, which can directly yield information regarding the oxidation states of copper, such as XAS ,,, and XPS/Auger, − ,,, and which had, in at least two cases, , also been used to sample systems engaged in high-pressure methanol synthesis. Indeed, the former commented upon the work of Chinchen and Waugh, though largely in defense of their own choice of feed composition, which had been commented upon as “unusual” …”

Section: –1989mentioning

confidence: 89%

“…Moreover, and with reference to the comparative XRD measurements of Bulko et al, 61 we see that the partitioning of phases determined using XPS 74 (Figure 10c) bears a quite startling similarity to the fractions of amorphous (XRD invisible) copper that had been implied to exist over the compositional range from quantitative XRD measurements. 61 From a methodological point of view, these first applications of XAS 69,71 and XPS 72−74 both required that the prepared catalyst was transferred post reduction to the measurement system, as did a number studies conducted in this decade regarding various aspects of the CZA formulation. 70,79,80 As the decade progresses, however, a decided shift toward in situ studies appears.…”

Section: −1989mentioning

confidence: 99%

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The Enigma of Methanol Synthesis by Cu/ZnO/Al₂O₃-Based Catalysts

Beck,

Newton,

van de Water

et al. 2024

Chem. Rev.

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The activity and durability of the Cu/ZnO/Al 2 O 3 (CZA) catalyst formulation for methanol synthesis from CO/CO 2 /H 2 feeds far exceed the sum of its individual components. As such, this ternary catalytic system is a prime example of synergy in catalysis, one that has been employed for the large scale commercial production of methanol since its inception in the mid 1960s with precious little alteration to its original formulation. Methanol is a key building block of the chemical industry. It is also an attractive energy storage molecule, which can also be produced from CO 2 and H 2 alone, making efficient use of sequestered CO 2 . As such, this somewhat unusual catalyst formulation has an enormous role to play in the modern chemical industry and the world of global economics, to which the correspondingly voluminous and ongoing research, which began in the 1920s, attests. Yet, despite this commercial success, and while research aimed at understanding how this formulation functions has continued throughout the decades, a comprehensive and universally agreed upon understanding of how this material achieves what it does has yet to be realized. After nigh on a century of research into CZA catalysts, the purpose of this Review is to appraise what has been achieved to date, and to show how, and how far, the field has evolved. To do so, this Review evaluates the research regarding this catalyst formulation in a chronological order and critically assesses the validity and novelty of various hypotheses and claims that have been made over the years. Ultimately, the Review attempts to derive a holistic summary of what the current body of literature tells us about the fundamental sources of the synergies at work within the CZA catalyst and, from this, suggest ways in which the field may yet be further advanced.

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Section: –1989supporting

confidence: 90%

Section: −1989supporting

confidence: 88%

Section: –1989mentioning

confidence: 76%

Section: –1989mentioning

confidence: 89%

Section: −1989mentioning

confidence: 99%

See 3 more Smart Citations

The Enigma of Methanol Synthesis by Cu/ZnO/Al₂O₃-Based Catalysts

Beck,

Newton,

van de Water

et al. 2024

Chem. Rev.

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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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