A Study on the In situ Regeneration Effects of Commercial Deactivated SCR Catalyst

Abstract

A study on the in situ regeneration effect of commercial deactivated SCR catalyst which had been exposed to the off gas from the heavy oil fired power plant for a long time was carried out in a simulated in situ conditions by washing with distilled water and various acid solutions in a short time. The catalytic performance test of the regenerated SCR catalysts was carried out in the micro reactor with simulated off gas of the heavy oil fired power plant and all prepared catalysts were characterized by BET, Porosimeter, EDX (Energy Dispersive X-ray spectrometer) and ICP (Inductively Coupled Plasma) to investigate correlations between catalytic activity and surface characteristics of them. The characterization results of the regenerated catalysts showed that the specific surface area was restored 95% more than that of fresh catalyst. Under this study, the activity of the regenerated catalysts with acid solution (3~6 M) without using ultrasonic wave in a simulated in situ conditions was restored 90% more than that of the fresh catalyst. It was found that improved activity of regenerated catalyst was caused by removing the deactivating materials from the surface of the deactivated SCR catalyst through acid washing.

Current Catalyst Technology of Selective Catalytic Reduction (SCR) for NOx Removal in South Korea

“…When the acidity of the solution exceeds the optimal point, the dissolution effects of the impurity component deposited on the catalyst surface that caused the catalyst deactivation. Moreover, the leaching rate of vanadium and tungsten, which are the main active components, increases and eventually lead to catalyst deactivation [53].…”

“…Although research is being conducted worldwide to regenerate and use it, the currently studied regeneration method is to desorb the catalyst from the reactor and transport it to a regeneration plant to regenerate the degraded catalyst. In order to retain the original activity of the degraded catalyst, acid is used to remove the adsorbed coke and other particulate matters on the surface of the catalyst which was generally reported to be a time-consuming process [53].…”

“…Figure25. Conversion rate of NO over the prepared catalysts with sulfuric + nitric acid solution washing as a function of reaction temperature (space velocity = 6000 h −1 , NO/NH 3 ratio = 1:1, O 2 = 3.6 %(v/v), NO = 300 ppm, SO 2 = 400 ppm)[53].…”