Physico-Chemical and Catalytic Properties of Mesoporous CuO-ZrO2 Catalysts
Mesoporous CuO-ZrO 2 catalysts were prepared and calcined at 500˝C. The performance of the synthesized catalysts for benzylation of benzene using benzyl chloride was studied. The bare support (macroporous ZrO 2 ) offered 45% benzyl chloride conversion after reaction time of 10 h at 75˝C. Significant increase in benzyl chloride conversion (98%) was observed after CuO loading (10 wt. %) on porous ZrO 2 support. The conversion was decreased to 80% with increase of CuO loading to 20 wt. %.
... 20 wt. %. Different characterization techniques (XRD, Raman, diffuse reflectance UV-vis, N 2 -physisorption, H 2 -TPR, XPS and acidity measurements) were used to evaluate physico-chemical properties of CuO-ZrO 2 catalysts; the results showed that the surface and structural characteristics of the ZrO 2 phase as well as the interaction between CuO-ZrO 2 species depend strongly on the CuO content. The results also indicated that ZrO 2 support was comprised of monoclinic and tetragonal phases with macropores. An increase of the volume of monoclinic ZrO 2 phase was observed after impregnation of 10 wt. % of CuO; however, stabilization of tetragonal ZrO 2 phase was noticed after loading of 20 wt. % CuO. The presence of low-angle XRD peaks indicates that mesoscopic order is preserved in the calcined CuO-ZrO 2 catalysts. XRD reflections due to CuO phase were not observed in case of 10 wt. % CuO supported ZrO 2 sample; in contrast, the presence of crystalline CuO phase was observed in 20 wt. % CuO supported ZrO 2 sample. The mesoporous 10 wt. % CuO supported ZrO 2 catalyst showed stable catalytic activity for several reaction cycles. The observed high catalytic activity of this catalyst could be attributed to the presence of a higher number of dispersed interactive CuO (Cu 2+ -O-Zr 4+ ) species, easy reducibility, and greater degree of accessible surface Lewis acid sites.