The role of the oxidic support on the deactivation of Pt catalysts during the CO2 reforming of methane

Pt supported on ¿-Al2O3, TiO2 and ZrO2 are active catalysts for the CO2 reforming of methane to synthesis gas. The stability of the catalysts increased in the order Pt/¿-A12O3 < Pt/TiO2 < Pt/ZrO2. For all catalysts, the decrease in activity with time on stream is caused by carbon formation, which blocks the active metal sites for reaction. With Pt/TiO2 and Pt/ZrO2, deactivation started immediately after the start of the reaction, while the Pt/¿-A12O3 catalyst showed an induction period during which carbon was accumulated without affecting the catalytic activity

Synthesis and characterization of mesoporic materials containing highly dispersed cobalt

Highly dispersed Co particles in MCM-41 were prepared by direct addition of CoCl2 to the synthesis gel. The small clusters of Co did not sinter during reduction and sulfidation. Incorporation of Co into the MCM-41 lattice was not observed. The addition of Co to the synthesis gel did not alter the structural characteristics of the MCM-41 samples

Mechanism of Carbon Deposit/Removal in Methane Dry Reforming on Supported Metal Catalysts

The greater resistance to coke deposition for Pt/ZrO2 compared to Pt/Al2O3 in the CH4/CO2 reaction has been attributed to the higher reactivity of coke with CO2 on Pt/ZrO2 [1]. Hence, in this communication, the reaction of coke derived from methane (CHx: which is an intermediated in the reforming reaction and also a source of coke deposition) with CO2 was studied on Pt/Al2O3 and Pt/ZrO2 at 1070 K. The reactivity of coke itself on Pt, as measured by its reaction with H2, was higher on Pt/Al2O3 than on Pt/ZrO2. However, the reactivity of coke toward CO2 was lower. Hence, the difference between the two catalysts cannot be attributed to the difference in the reactivity of coke itself. Next, the ability of the active site to activate CO2 (probably oxygen defect sites on the support), as shown by CO evolution measurement in CO2 stream, was higher on Pt/ZrO2 than on Pt/Al2O3. Therefore, the high reactivity of coke toward CO2 on Pt/ZrO2 is attributed not to the intrinsic reactivity of coke itself but to the high activity of CO2 at oxygen defect sites of ZrO2 that are in the vicinity of Pt particles