1-04　Deposition characteristics of Si compounds on the De-NOx catalyst for PC boilers

Abstract

Since a large amount of NOx, that is one of air pollutants, arises from coal combustion process, the SCR method is generally applied for coal-fired power stations to reduce NOx emissions. In the SCR method, NH₃ is introduced into the flue gas at De-NOx catalyst, and NOx is reduced to N₂ by catalytic reaction. This De-NOx catalyst is located upstream of the exhaust gas treatment process, and exposed to a lot of soot and dust particles in the flue gas. Previous studies have revealed that the deterioration of De-NOx catalyst is caused by the deposition of the silica compounds on its surface. Then, the adhesion conditions of these silica compounds were experimentally clarified in this study. De-NOx catalyst samples were exposed to siloxane vapor in simulated flue gas. The formation of silica layer on the surface of De-NOx catalyst was observed by SEM/EDX. The experimental results suggested that silica layer became more explicit in gas including impurities, such as SO₂, NH₃, and NO.