The energy requirement has increased exponentially over the past decades due to industrialization and the changes of subsequent lifestyle. Almost 90% of the present energy source is based on the combustion of fossil fuels. Diesel engines are considered the most ideal power generators in transportation and industrial sectors owing to their fuel economy and efficiency. However, they suffer from the disadvantages of exhaust pollutants particularly oxides of nitrogen (NOx), which are facing increasingly stringent emission regulations which led to the search for alternative technologies. The technologies that allow for the highest NOx reduction are EGR (Exhaust gas recirculation), NOx absorbers, lean NOx catalyst system and SCR (Selective catalytic reduction). Selective Catalytic Reduction system (SCR) is an advanced active emissions control technology converts nitrogen oxides (NOx) with the aid of catalyst into diatomic nitrogen (N2), and water (H2O). To take place the conversion reactions, a reducing agent is need, which is usually a solution of urea () and high purity water (distilled water) known as AdBlue. AdBlue is decomposed into ammonia and water vapour, and then decomposed ammonia is adsorbed on the catalyst substrate then adsorbed ammonia reacts with oxides of nitrogen and reduced into eco-friendly nitrogen and water vapour.
