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Methanation of CO2 over alkali-promoted Ru/TiO2 catalysts: I. Effect of alkali additives on catalytic activity and selectivity

Petala Athanasia, Panagiotopoulou Paraskevi

Πλήρης Εγγραφή


URI: http://purl.tuc.gr/dl/dias/12A1CE43-D3BC-4AA5-8EFC-C70B42F8C96D
Έτος 2018
Τύπος Δημοσίευση σε Περιοδικό με Κριτές
Άδεια Χρήσης
Λεπτομέρειες
Βιβλιογραφική Αναφορά Μη διαθέσιμο για την επιλεγμένη γλώσσα
Εμφανίζεται στις Συλλογές

Περίληψη

The effect of alkali promotion of TiO2 on the CO2 hydrogenation activity and selectivity has been investigated over 0.5%Ru/TiO2 and 5%Ru/TiO2 catalysts of different promoter type (Li, Na, K, Cs) and variable promoter loading (0.0–0.40 wt.%). The effect of alkali promotion was found to be more pronounced over catalysts of low Ru loading (or small Ru crystallites). In the case of 0.5%Ru/TiO2 catalysts, both catalytic activity and methane selectivity are strongly enhanced with the addition of small amounts (0.2 wt.%) of alkalis following the order of TiO2 (unpromoted) < Li ∼ K < Cs < Na. The intrinsic reaction rate exhibits a volcano-type dependence on the sodium content. Optimal results were obtained for 0.5%Ru/TiO2 catalyst containing 0.2 wt.% Na, the specific activity of which is about 3 times higher, compared to that of the unpromoted sample. In the case of 5%Ru/TiO2 catalysts, alkali addition does not practically affect catalytic activity and selectivity. Turnover frequency of 0.5%Ru/0.2%Na-TiO2 catalyst is higher than that measured over 5%Ru/TiO2, indicating that small amounts of alkalis can replace part of precious metals, reducing the cost and increasing the efficiency of the CO2 methanation process.

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