Effect of γ-irradiation and ZnO-doping of CuO/TiO 2 system on its catalytic activity in ethanol and isopropanol conversion

Abstract

The effects of γ-irradiation (0.4–1.6 MGy) and ZnO-doping (1–6 mol%) of CuO/TiO 2 system on its surface and catalytic properties were investigated using XRD, nitrogen adsorption at−196 °C and ethanol and isopropanol conversion. The catalytic reactions were carried out at 250–400 °C using micro pulse technique. The results revealed that all investigated solids heated at 400 and 600 °C consisted of TiO 2 (anatase) as major phase besides TiO 2 (rutile) as minor phase together with CuO phase. The anatase and CuO phases existed as nano-crystallized solids having crystallite size varying between 5.5 and 21.3 nm and between 8.2 and 23.5 nm for anatase and CuO phases, respectively. ZnO-doping and γ-irradiation brought about a progressively significant decrease in the crystallite size of TiO 2 and CuO phases which increased by increasing the calcination temperature of the system investigated from 400 to 600 °C. ZnO-doping and γ-irradiation increased the specific surface areas of the treated solids to an extent proportional to the amount of dopant added and the dose of γ-rays absorbed. All solids investigated were highly selective in ethanol and isopropanol conversion reactions, which proceed via dehydration yielding only ethene and propene, respectively. The catalytic activity of all solids was found to decrease by increasing the calcination temperature from 400 to 600 °C. ZnO-doping conducted at 400 °C exerted no significant change in the activity of doped solids. γ-Irradiation of the solids calcined at 400 °C led to a limited increase in their catalytic activities. On the other hand, ZnO-doping and γ-irradiation (0.4 MGy) of solids calcined at 600 °C resulted in an increase in their catalytic activities. The increase was, however, more pronounced in case of γ-irradiation at a dose of 0.4 MGy.