| dc.description.abstract | NOx storage reduction (NSR) has been pointed out as a possible solution to meet the stringent emission ceilings for NOx. The NOx storage reduction catalyst is designed to work under cyclic conditions, alternating between oxidizing (lean) reducing (rich) atmospheres. In oxygen rich atmospheres, the catalyst stores NOx species, which are reduced when the reducing atmosphere is introduced. These catalyst are mostly based on precious metals and barium, where the precious metal is reducing NOx during the reducing cycle, while barium stores NOx during the oxidative cycle. As an alternative to the expensive precious metals, copper has been shown to be able to selectively reduce NOx in oxidative atmospheres in the presence of hydrocarbons (HC-SCR).This thesis is concerned with investigating the possibilities of NOx storage reduction on copper and barium containing micro- and meso porous materials. Copper and Barium containing silica gels have been synthesized via the APD method. Zeolite ZSM-5 and Silicalite-1 samples have been synthesized and copper and barium have been introduced by ion exchange and deposition. The samples have been characterized with powder X-ray diffraction, ICP-MS, and Surface area and porosity measurements. The catalytic activity of the samples towards the reduction of NOx in the lean-rich atmospheres were measured and compared to that during selective catalytic reduction.Results show that the introduction of barium to the Silicalite-1 and ZSM-5 systems is not straight forward, and that significant amounts of barium demanded several successive ion-exchange and depostion treatments. Results from catalytic measurements show that copper and barium containing samples performed better during the selective catalytic reduction of NOx than in the cyclic lean-rich atmospheres, and did not show any signs of storage capacity on any of the prepared samples tested in this work. | nb_NO |
