SOx uptake and release properties of TiO2/Al2O3 and BaO/TiO2/Al2O3 mixed oxide systems as NOx storage materials

Date
2012-04-30
Authors
Şentürk, G. S.
Vovk, E. I.
Zaikovskii, V. I.
Say, Z.
Soylu, A. M.
Bukhtiyarov, V. I.
Ozensoy, E.
Journal Title
Journal ISSN
Volume Title
Publisher
Elsevier
Abstract

Titania was used as a promoter to obtain novel materials in the form of TiO2/Al2O3 (Ti/Al) and BaO/TiO2/Al2O3 (Ba/Ti/Al, containing 8 wt% or 20 wt% BaO) that are relevant to NOx storage reduction (NSR) catalysis. Two different protocols (P1, P2) were utilized in the synthesis. Ti/Al(P1) manifests itself as crystallites of TiO2 on -Al2O3, while Ti/Al(P2) reveals an amorphous AlxTiyOz mixed oxide. The structures of the synthesized materials were investigated via TEM, EDX, BET analysis and XPS while the catalytic functionality/performance of these support materials upon SOx and subsequent NOx adsorption were investigated with TPD and in situ FTIR spectroscopy. Ti/Al(P1, P2) revealed a high affinity towards SOx. Overall thermal stabilities of the adsorbed SOx species and the total SOx uptake of the Ba-free samples increase in the following order: TiO2(anatase) -Al2O3 < Ti/Al(P1) < Ti/Al(P2). The superior SOx uptake of Ti/Al(P1, P2) support materials can be tentatively attributed to the increasing specific surface area upon TiO2 promotion and/or the changes in the surface acidity. Promotion of BaO/Al2O3 with TiO2 leads to the attenuation of the SOx uptake and a significant decrease in the thermal stability of the adsorbed SOx species. The relative SOx adsorption capacities of the investigated materials can be ranked as follows: 8Ba/Ti/Al(P1) < 8Ba/Ti/Al(P2) < 8Ba/Al ∼ 20Ba/Ti/Al(P1) < 20Ba/Al < 20Ba/Ti/Al(P2).

Description
Keywords
Al2o3, Bao, Tio2, Anatase, Sulfur Poisoning, Deno(x), Nox, Sox, Sulfation, NSR, LNT, HDS, Claus process
Citation