Isomerization over zinc oxide

In homogeneous (15, 16) and heterogeneous (17) base catalyzed reactions, such species, with anionic character, are firmly established as intermediates. It seems clear that a similar species must be regarded as a prime candidate for an intermediate in isomerization over zinc oxide. Regardless of what the isomerization intermediate is, however, it is clearly different from that involved in isomerization over metals. 

Fig. 24. cis-Butene isomerization over zinc oxide O, eis-butene (right-hand ordinate) A, [Pg.45]

Figure 24 shows the cfs-butene isomerization over zinc oxide as a function of time at room temperature (7/). On a per unit area basis the initial rate at room temperature is 4 X 1010 molecules/sec cm2, a rate roughly one third that reported for alumina (69). Since the activation energy for alumina is less than that found for zinc oxide, this means that zinc oxide is comparable (on a per unit area basis) to alumina as an isomerization catalyst at slightly higher temperatures. 

Hydrogenation and Isomerization over Zinc Oxide R. J. Kokes and A. L. Dent... 

Kokes and Dent by combining IR spectroscopy with hydrogen isotope techniques, and by applying kinetic and stereochemical considerations were able to determine the intermediate surface species in the hydrogenation and isomerization of simple olefins over zinc oxide. 

Butanol, reaction over reduced nickel oxide catalysts, 35 357-359 effect of ammonia, 35 343 effect of hydrogen, 35 345 effect of pyridine, 35 344 effect of sodium, 35 342, 351 effect of temperature, 35 339 over nickel-Kieselguhr, 35 348 over supported nickel catalysts, 35 350 Butanone, hydrogenation of, 25 103 Butene, 33 22, 104-128, 131, 135 adsorption on zinc oxide, 22 42-45 by butyl alcohol dehydration, 41 348 chemisorption, 27 285 dehydrogenation, 27 191 isomerization, 27 124, 31 122-123, 32 305-308, 311-313, 41 187, 188 isomerization of, 22 45, 46 isomers... 

The spectrum is identical to that of adsorbed allene, implyingthat the adsorbed species is the propargyl anion. In agreement with this conclusion is the isomerization of allene to methylacetylene when the former is circulated over the activated zinc oxide employed. ... 

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