The nitrogen oxide (NOx) is one of the most dangerous pollutants in air which produced from the reaction of nitrogen and oxygen gases in the air during combustion, especially at high temperatures. NOx gases react to form smog and acid rain as well as being central to the formation of fine particles (PM) and ground level ozone, both of which are associated with adverse health effects. Therefore, it is very important to reduce the amount of NOx to save the environment.
Selective Catalytic Reduction (SCR) and Lean NOx Trap (LNT) catalyst are the common technology to remove NOx. Metal oxide doped with noble metal was usually used as LNT catalyst. Noble metal catalyst has disadvantages such as high cost and low thermal stability. It is necessary to find a way to replace the noble metal.
Perovskite LaCoO3 is the material which can replace the noble metal used in LNT catalyst due to its low cost, has catalytic capability, and good thermal stability. V2O5/WO3-TiO2 is the SCR catalyst material which usually use in diesel engine because of its active site and thermal stability and easy to fabricate. But the specific surface area of those material is very low. It was related to the presence of the active site. The low specific surface area and active site cause the performance of the catalyst to remove the NOx is not optimal.
Mesoporous silica KIT-6 was usually used as hard template because it has large specific surface area and interconnected pore to fabricate the mesoporous powder. The silica material is also believed can improve the stabilization of TiO2. The purpose of this study are attempt to fabricate the mesoporous LaCoO3 and increase the specific surface area of V2O5/WO3-TiO2 then obtain the catalyst material which has higher active site and stable wider range of temperature. In this study, the mesoporous perovskite-type oxide LaCoO3 which prepared by citric acid method and impregnation technic on the hard template and the complex metal oxide V2O5/WO3-TiO2 which prepared by sol gel method by adding mesoporous silica were used to investigate the improvement of the catalyst caused by mesoporous silica. The catalysts were characterized by XRD, BET, FT-IR, and TEM to observed the improvement of structure, physical properties, and active site of the catalyst powder. The NOx conversion test was performed to observe de-NOx catalyst capability.
The results indicate that the mesoporous LaCoO3 powder with has large specific surface area around 75 m2g-1 was successfully synthesized by the impregnation technic on the hard template method. The perovskite was impregnated into the interconnected channel of KIT-6 to replicate the pore structure and obtain the large specific surface area. The hard template was also removed so it did not react during de-NOx capability test. The result of de-NOx capability was higher than non-mesoporous LaCoO3, changed from 70% to up to 90%.
The specific surface area of V2O5/WO3-TiO2 was increase 25 times and the range of temperature reaction become wider from 250 to 375 oC. The adding of mesoporous silica KIT-6 successfully enlarges the specific surface area and it can prevent the TiO2 rutile phase transformation during calcination and increase the amount of acid site.

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