Synthesis and Physico-Chemical Characterization of CeO 2 /ZrO 2 -SO 4 2- Mixed Oxides

Environmentally friendly solid-acid catalysts CeO2/ZrO2- SO4 2- were prepared by the sol gel method varying CeO2 content (10, 20 and 30 wt%) and using sulfation in situ, maintaining the sulfate ions amount present in the materials at 20 wt%. ZrO2 and ZrO2-SO4 2- were also prepared for comparison proposes using the same synthesis method. The materials were characterized by X-ray diffraction, ni- trogen physisorption, potentiometric titration with n-butylamine, de- composition of 2-propanol and n-pentane isomerization. The specific surface area of ZrO2-SO4 2- was high (160 m 2 /g) compared with the unmodified ZrO2 (80 m 2 /g), however this area decreased with increas- ing the CeO2 content (37-100 m 2 /g). There was no significant effect of CeO2 on the tetragonal structure of ZrO2-SO4 2- . The variation of acid sites amount runs parallel to the change of specific surface area. The acid sites amount decreased with increasing cerium oxide content. The decomposition of 2-propanol results fundamentally in the forma- tion of dehydration products such as propylene and diisopropyl ether, both involving acid sites. In addition, a good performance during the n-pentane isomerization was observed for these materials. The selectivity towards isopentane reaches 84% when the Pt/CeO2/ZrO2- SO4 2- catalyst with the highest CeO2 content was used.