Zro2 As A Supporter For Pd, Pd-ag
ZrO2 AS A SUPPORTER FOR Pd, Pd-Ag
CATALYSTS IN CO OXIDATION
E. V. Ischenko, N. A. Boldyreva., A. V. Yatsimirsky, N. Y. Neschimenko
National Kyiv Taras Shevchenko University Volodymyrska str., 64, Kyiv, Ukraine, 01017 e-mail: andrew@cvu.kiev.ua
It was earlier shown, that Pd-Ag catalysts with a definite ratio Pd:Ag had higher activity in an CO oxidation, than pure metals. It was explained by existence of active centres on a surface of a binary mixture Pd-Ag. The centres are monoatomic on the palladium and adsorb CO in the weak linear form, which is active in the catalytic reaction.
> The investigation of activity in CO oxidation on Pd, Pd-Ag catalysts marked on ZrO2 is submitted and the kinetic regularity of reacting is studed. The measure of catalytic activity was the temperature of 100% transformation from CO into СО2 (T100). The catalytic activity of Pd/ZrO2 is rising with the increasing of palladium containing and passes the maximum (T100 =118 0C for sample 5 mass. % Pd).
In excess of oxygen samples Pd-Ag / ZrO2 show higher catalytic activity, than Pd/ZrO2. At a ratio О2: CO = 10 transformation conversion of CO on Pd-Ag / ZrO2 at 1170С set up 80% and Pd/ ZrO2 set up 30-40 %.
In relation of reaction speed to concentration CO and О2 on the Pd/ZrO2 sample the hysteresis phenomena are watched. For Pd-Ag/ZrO2 curves of relation of reaction speed from concentrations of CO and O2 look like curves tend to a saturation, the hysteresis are absent.
The obtained data indicative that CO oxidation on Pd/ZrO2 and Pd-Ag/ZrO2 catalysts proceeding on different active centres of a surface.
The mechanism of reaction and kinetic equation presenting experimental data is offered.
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