Browsing by Subject "Catalytic performance"

Filter results by typing the first few letters
Now showing 1 - 2 of 2
  • Thumbnail Image
    ItemOpen Access
    Metal dicyanamides as efficient and robust water-oxidation catalysts
    (Wiley Blackwell, 2017) Nune, S. V. K.; Basaran, A. T.; Ülker, E.; Mishra, R.; Karadas, F.
    Non-oxide cobalt-based water-oxidation electrocatalysts have received attention recently for their relative ease of preparation, they are stable both in acidic and basic media, and they have higher turnover frequencies than cobalt oxides. Recent studies show that one of the main bottlenecks in the implementation of non-oxide systems to water splitting is the low number of active metal sites, which is in the order of nmol cm−2. Herein, a new series of non-oxide water-oxidation catalysts has been introduced to the field. Cobalt dicyanamides are observed to have around four times higher surface active sites and better catalytic performances than cyanide-based systems. Long-term catalytic studies (70 h) at an applied potential of 1.2 V and electrochemical studies performed in solutions in pH values of 3.0–12.0 indicate that the compounds are robust and retain their structures even under harsh conditions. Moreover, the addition of Ni impurities to cobalt dicyanamides is a feasible method to improve their catalytic activities.
  • Thumbnail Image
    ItemOpen Access
    Sulfur-tolerant BaO/ZrO2/TiO2/Al2O3 quaternary mixed oxides for deNOX catalysis
    (Royal Society of Chemistry, 2017) Say, Z.; Mihai, O.; Tohumeken, M.; Ercan, K. E.; Olsson, L.; Ozensoy, E.
    Advanced quaternary mixed oxide materials in the form of BaO/Al2O3/ZrO2/TiO2 functionalized with Pt active sites (i.e. Pt/BaO/AZT) were synthesized and structurally characterized via XRD and BET in comparison to a conventional Pt/20BaO/Al benchmark NSR/LNT catalyst. The interactions of these catalysts' surfaces with SOx and NOx gases were monitored via in situ FTIR and TPD. There exists a delicate trade-off between NOx storage capacity (NSC) and sulfur uptake/poisoning which is strongly governed by the BaO loading/ dispersion as well as the surface structure and acidity of the support material. Flow reactor measurements performed under realistic catalytic conditions show the high NOx activity for the Pt/20BaO/AZT catalyst at 573 K. After sulfur poisoning and subsequent regeneration at 773 and 973 K, Pt/20BaO/AZT surpassed the NOx catalytic performance at 573 K of all other investigated materials including the conventional Pt/ 20BaO/Al benchmark catalyst.