Chemical state of copper during methanol synthesis: reply to Chinchen and Waugh

Journal Article · Wed Jan 01 00:00:00 EST 1986 · J. Catal.; (United States)

DOI:https://doi.org/10.1016/0021-9517(86)90064-3· OSTI ID:5297911

Fleisch, T H; Mieville, R L

Copper-based methanol synthesis catalysts have been the subject of many studies. Some of them have focused on the nature of the active Cu site(s) but the subject is still rather controversial. All researchers find metallic Cu as the predominant Cu species on Cu/ZnO/Al/sub 2/O/sub 3/ and Cu/ZnO/Cr/sub 2/O/sub 3/ catalysts during methanol synthesis; however, the amount and catalytic importance of the small concentrations of Cu/sup +/ accompanying Cu is at the center of a controversy. The amount of Cu/sup +/ ions present during methanol synthesis can depend, among other things, on catalyst composition, gas composition (e.g., presence of CO/sub 2/H/sub 2/O), and reaction conditions. The authors discuss the results of their previous studies. The authors believe that there is sufficient evidence in the literature that completely reduced Cu-based catalysts are very good methanol synthesis catalysts. Thus, metallic copper sites must be active sites for this reaction. On the other hand, there is also evidence of incomplete copper reduction under certain reaction conditions leading to a mixture of mainly Cu and some Cu/sup +/. The question of whether Cu/sup +/ is another or even a much more active site for methanol formation than Cu has not yet been answered. It would have been interesting if Chinchen and Waugh had shown a correlation between the performance of their catalysts and the amount of surface oxidized copper. In their own work, attempts to correlate methanol synthesis rates with relative amounts of Cu and Cu/sup +/ were not successful because the reduction of CuO to Cu was completed at the onset of measurable CO conversion at about 130/sup 0/C. The authors did, however, observe Cu/sup +/ as intermediate in the reduction of Cu/sup 2 +/ to Cu and, as already mentioned, after only minute air exposure of used catalysts. 17 references.

• Research Organization: Amoco Corp., Naperville, IL (USA)
• OSTI ID: 5297911
• Journal Information: J. Catal.; (United States), Vol. 97:1
• Country of Publication: United States
• Language: English

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