Methanol Reactions on Copper

Lawson, Alexander (1962) Methanol Reactions on Copper. PhD thesis, University of Glasgow.

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The catalytic dehydrogenation of methyl alcohol to formaldehyde, carbon monoxide and hydrogen has been studied on various copper foil and wire catalysts. Pure copper foil and wire were found to be inactive towards the decomposition of methanol, and yet many authors have reported decomposition occurring on reduced copper powder activated by oxidation/reduction techniques. The present author has found that once copper foil or wire is oxidised to predetermined extents, then a pure dehydrogenation reaction occurs. No dehydration of the alcohol has been observed. The activity of the catalyst has been ascribed to the presence of a p-type semiconducting cuprous oxide defect structure in the catalyst. This is contrary to present opinion which suggests that dehydrogenation is facilitated by n-type oxide catalysts. It is therefore proposed that the activity imparted to copper powder catalysts by oxidation/reduction techniques is due to the presence of unreduced copper oxide in the powder, and it is suggested that careful interpretation of results obtained on reduced powder catalysts is necessary. The course of the dehydrogenation reaction, and the secondary reactions produced by interaction of the products of decomposition with the catalyst oxide, was found to depend critically upon the degree and type of oxidation of the catalyst. Thus, two secondary reaction mechanisms have been proposed as occurring on catalysts corresponding to low and high p-typeness respectively. Oxygen-18 studies have indicated that the production of carbon dioxide from catalysts corresponding to high p-typeness probably proceeds via. the formation of a carbonate surface complex. Such a complex has already been tentatively suggested by several authors. In the case of catalysts exhibiting high p-typeness, a partial poisoning of the dehydrogenation reaction was observed to occur, with consequent increase in the yield of formaldehyde. The yield of formaldehyde was also increased by work hardening the copper wire prior to oxidation. This result may be of considerable interest to those workers intent on preparing formaldehyde by dehydrogenation of methanol. In addition, the decomposition of formic acid has been studied on work hardened and annealed copper wires. The rate of decomposition was found to be less on work hardened wires, and the reason for this, based on vacancy diffusion, is suggested.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Keywords: Organic chemistry
Date of Award: 1962
Depositing User: Enlighten Team
Unique ID: glathesis:1962-79439
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 05 Mar 2020 09:44
Last Modified: 05 Mar 2020 09:44

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