Influence of carbon-chlorine surface complexes on the properties of tungsten oxide supported on activated carbons.: 2.: Surface acidity and skeletal isomerization of 1-butene

Chlorinated activated carbons and the respective tungsten oxide catalysts supported on them were tested as catalysts in the decomposition reaction of 2-propanol and characterized by measurement of their pH(PZC). Supported catalysts were also used in the skeletal isomerization of 1-butene. Results found show that an increase in the chlorine content of the support increases the total surface acidity, as measured by the pH(PZC), of both the support and the supported catalysts. However, there is also a decrease in their Bronsted type acidity, as determined from the results obtained from the dehydration reaction of 2-propanol. Thus, it seems that the effect of chlorine is to increase Lewis type acidity in both the support and the supported catalyst. In addition, during the dehydration of 2-propanol there was a partial reduction of W(VI) to W(V) in most of the catalysts, which brought about a restructuring of the metal oxide particles. Isomerization of 1-butene gives only isobutene and trans-2-butene. Selectivity to obtain isobutene decreases when the reaction temperature and total conversion increases. Activity to obtain isobutene shows the same trend as the dehydration of 2-propanol and decreases when the chlorine content of the support increases.