Effect of biodiesel components on selective reduction of NOx

[摘要] The reduction of nitrogen oxides (NO\(_X\)) from diesel engine exhausts gas through the addition of different methyl esters in hydrocarbon selective catalytic reduction (HC-SCR) over silver-alumina (Ag/Al\(_2\)O\(_3\)) environmental catalysts has been investigated. The selected methyl esters are those which are usually found in the majority of biodiesel composition from different feedstocks. The effects of biodiesel components in removing NO\(_X\) have been found. However lighter methyl esters activate at higher temperatures compared to heavier, they reach to higher NO\(_X\) conversion and peak in around 40% of NO\(_x\) reduction. Those effects are a consequence of the formation of i) active hydrocarbon components and ii) nitrogen containing components such as NO\(_2\) and NH\(_3\), which in reaction with NO ideally will reduce NO\(_X\) components to produce N\(_2\), H\(_2\)0 and carbonaceous species. Hydrogen (H\(_2\)) has been added in order to promote the conversion of NO\(_X\) and investigate the effects of methyl esters under the addition of hydrogen. It shows more effect on longer chain methyl esters similar to the activity on paraffinic hydrocarbon components. It is suggested that H\(_2\) enhances the NO\(_X\) conversion by activation of oxygen into oxygenated reactive species, the formation of reactive species such as NH\(_3\) and NO\(_2\) as well as reduces coke formation and nitrates deposits on the catalyst active sites.

[发布机构] University:University of Birmingham;Department:School of Engineering, Department of Mechanical Engineering

[关键词] T Technology;TJ Mechanical engineering and machinery