title: Characterization and reactivity of copper oxide catalysts supported on TiO2-ZrO2.
abstract: A series of copper catalysts supported on TiO2-ZrO2 with copper loading varying from 1.0 to 21.6 wt % were prepared by a wet impregnation method. The catalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy, electron spin resonance (ESR), temperature programmed reduction (TPR), and Brunauer-Emmett-Teller specific surface area measurements. Copper dispersion and metal area were determined by N2O decomposition by the passivation method. XRD results suggest that the copper oxide is present in a highly dispersed amorphous state at copper loadings <16.8 wt % in the sample and as a crystalline CuO phase at higher Cu loadings. Copper dispersion increases with Cu loading up to 5.1 wt % and levels off at higher loadings. The XPS peak intensity ratios of Cu 2p(3/2)/Ti 2p(3/2) and Cu 2p(3/2)/Zr 3d(5/2) were compared with the copper dispersion calculated from N2O decomposition. ESR results suggest the presence of two types of copper species on the TiO2-ZrO2 support. TPR profiles reveal the presence of highly dispersed copper oxide at lower temperatures and bulk CuO at higher temperatures. The catalytic properties were evaluated for the vapor-phase dehydrogenation of cyclohexanol to cyclohexanone and related to the dispersion of Cu on TiO2-ZrO2.
authors.affiliation: Catalysis Division, Indian Institute of Chemical Technology, Hyderabad 500 007, India. kvrchary@iict.res.in
authors.forename: Komandur V R
authors.initials: KV
authors.lastname: Chary
authors.forename: Guggilla Vidya
authors.initials: GV
authors.lastname: Sagar
authors.forename: Dhachapally
authors.initials: D
authors.lastname: Naresh
authors.forename: Kottapalli Kalyana
authors.initials: KK
authors.lastname: Seela
authors.forename: Bojja
authors.initials: B
authors.lastname: Sridhar