Artículos de revistas
Deep oxidation of propane on Pt-supported catalysts: Drastic turnover rate enhancement using zeolite supports
Fecha
2004-03Registro en:
Garetto, Teresita Francisca; Rincon, Eduardo Ricardo; Apesteguia, Carlos Rodolfo; Deep oxidation of propane on Pt-supported catalysts: Drastic turnover rate enhancement using zeolite supports; Elsevier Science; Applied Catalysis B: Environmental; 48; 3; 3-2004; 167-174
0926-3373
CONICET Digital
CONICET
Autor
Garetto, Teresita Francisca
Rincon, Eduardo Ricardo
Apesteguia, Carlos Rodolfo
Resumen
The combustion of propane was studied on Pt supported on MgO, alumina, and zeolites KL, HY, ZSM5 and Beta. Samples contained a similar amount of Pt, between 0.32 and 0.44%, and were characterized by employing a variety of physical and spectroscopic techniques. The catalyst activities were evaluated through both conversion versus temperature (light-off curves) and conversion versus time catalytic tests. Kinetic studies showed that the reaction is first order in propane, and zero (Pt/Al2O3, Pt/MgO) or negative (Pt/zeolites) orders in oxygen. Apparent activation energies (Ea) and pre-exponential factors (A) were determined and it was verified that the experimental data obey a Constable relation (ln A = mEa + c). Pt/Al2O3 catalysts of different metallic dispersions were prepared for investigating the effect of Pt crystallite size on combustion activity. It was found that propane oxidation is a structure insensitive reaction on Pt/Al2O3. Propane oxidation turnover rates (TOF) followed the order: Pt/MgO < Pt/Al2O3 Pt/KL < Pt/HY ≤ Pt/ZSM5 < Pt/Beta. The TOF values on Pt/acid zeolites were more than two orders of magnitude higher than on Pt/Al2O3. Propane oxidation activity was also significantly higher on Pt/KL
as compared to Pt/Al2O3, despite that Al2O3 and zeolite KL supports exhibited similar acid sites density and strength. This result showed that the support acid strength did not have a major influence on propane combustion activity. Areal propane uptake was more than one order of magnitude higher on Pt/zeolites than on Pt/Al2O3 and this drastic increase in the density of propane adsorbed species may promote the alkane oxidation rate. It is proposed that the enhanced combustion activity obtained on Pt/zeolites is associated with an additional oxidation pathway from propane adsorbing on the metal-oxide interface region and reacting with oxygen spilled-over from the metal surface.