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Optimal promotion by rubidium of the CO + NO reaction over Pt/γ-Al2O3 catalysts

Konsolakis Michail, Gentekakis Ioannis, Lambert Richard M., Palermo Alejandra

Πλήρης Εγγραφή


URI: http://purl.tuc.gr/dl/dias/E01EFB66-DD89-46E9-9ECC-1D78FF763BAB
Έτος 2001
Τύπος Δημοσίευση σε Περιοδικό με Κριτές
Άδεια Χρήσης
Λεπτομέρειες
Βιβλιογραφική Αναφορά M. Konsolakis, I. V. Yentekakis, A. Palermo and R.M. Lambert, "Optimal promotion by rubidium of the CO + NO reaction over Pt/γ-Al2O3 catalysts", Appl. Catal. B, vol. 33, no. 4, pp. 293-302, Oct. 2001. doi:10.1016/S0926-3373(01)00183-7 https://doi.org/10.1016/S0926-3373(01)00183-7
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Περίληψη

The reduction of NO by CO over Rb-promoted Pt/γ-Al2O3 catalysts has been investigated over a wide range of temperature (ca. 200–500°C), partial pressures of reactants and promoter loadings. For purposes of comparison, K- and Cs-promoted Pt/γ-Al2O3 catalysts were tested under the same conditions. Rubidium strongly enhanced both catalytic activity and N2-selectivity. Rate increases by factors as high as 110 and 45 for the production of N2 and CO2, respectively, relative to unpromoted Pt were obtained, accompanied by substantial increase in N2-selectivity (e.g. from 24 to 82% at 350°C and [CO]=0.5%, [NO]=1%). Under stoichiometric conditions, Rb-promoted catalysts gave 100% conversion of both reactants with 100% selectivity towards N2 at T∼350°C and at an effective reactant contact time of only ∼0.5 s. In contrast, under the same conditions unpromoted Pt delivered <30% conversion and poor N2-selectivity (approximately <40%); even at 480°C the conversion was only ∼60%. The observed promotional effects are ascribed to alkali-induced changes in the chemisorption bond strengths of CO, NO and NO dissociation products which lead to the observed activity enhancement and dependence of N2-selectivity on promoter loading. The effects of K-promotion mirror those of Rb-promotion, but are significantly less pronounced. Rb is the best alkali promoter.

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