Catalytic properties of Ag/Al2O3 for complete oxidation of benzene with ozone at 295-373 K were studied and compared with those of Mn/Al2O3. At the reaction temperature of 295 K, the Ag/Al2O3 catalysts showed selectivity to CO x (ca. 80%) higher than that of the oxide of metals in the first transition series (Fe, Mn, Co, Ni, Cu) supported on Al2O3, which had selectivities of 28-62%. The catalyst showed gradual deactivation from accumulation of byproduct compounds on the catalyst surface. FIR studies revealed that the byproduct compounds consisted of easily decomposable species and hardly decomposable species. The rate for benzene oxidation linearly increased with Ag loadings (∼15 wt %) and was not improved at higher loading levels. The ratios of ozone decomposition to benzene oxidation and ozone decomposition to COx selectivity were evaluated to be 7.5 and 80%, respectively, and they were independent of benzene conversion. The Ag/Al 2O3 catalyst showed steady-state activities at a reaction temperature of 313-373 K, and the conversion increased with the increase in the reaction temperature. The presence of water vapor in the reaction gas inhibited the catalyst deactivation, and steadystate activity was obtained at a reaction temperature of 295 K, while it did not affect the activities for benzene oxidation but improved the CO2 selectivity.
All Science Journal Classification (ASJC) codes
- General Chemistry
- Environmental Chemistry