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The effect of Al2O3-ZrO2, Al2O3-TiO2 and Al2O3-La2O3 mixed oxides on the deactivation of bifunctional Pt-Sn/ Al2O3 reforming catalysts has been investigated. The n-heptane reforming at 500°C was used as a test reaction. Changes in the catalytic behavior due to differences of the acidity and the support-metal interaction were observed. Levenspiel´s and Beltramini´s deactivation models were developed assuming a series fouling for the carbonaceous deposits. Through the Beltraminis model it was possible to distinguish the amount of acidity that participates in the deactivation processes. Both models successfully correlated with the experimental profiles of n-heptane activity decay. The following deactivation decreasing order, Al2O3-TiO2-1&gt;Al2O3-ZrO2-25&gt;Al2O3-TiO2-2&gt; Al2O3&gt;Al2O3-La2O3-10 was found with both deactivation models. A quasi-linear correlation between the deactivation order and the coke formation kinetic constant (Levenspiels parameters) was observed. The catalyst acidity and the n-heptane conversion were correlated with Beltraminis model. It was found that a high acidity (12 X 10-17 acid sites/g cat.) or metal dispersion (83%) increases the catalyst deactivation and it is necessary to have a balance of active sites in order to have a catalyst working as a bifunctional catalyst.  On the other hand, the auto-regeneration Beltraminis parameter suggests that the lowest deactivation of the Pt-Sn/ Al2O3-La2O3-10 catalyst is attributed to the cleaning capacity of the active sites. It was observed that the highest deactivation (80-92%) of the platinum-tin catalysts supported in alumina-titania mixed oxides were a result of the strong metal-support interaction (SMSI) effect. The Pt-Sn/Al2O3-La2O3-10 showed the best catalytic behavior with high initial and residual conversions (70 and 48%, respectively) and low deactivation (17 %) at a 50-minute reaction time. Furthermore, in the Pt-Sn/Al2O3 catalyst, the benzene yield was 1%, while the Pt-Sn/Al2O3-La2O3-10 showed a total inhibition of benzene production yield at residual conversions.

The Influence Of The Support On The Deactivation Behaviour of Pt-Sn Reforming Catalysts