Abstract
Spent selective catalytic reduction (SCR) catalyst installed in power and incineration plants is used to convert nitrogen oxide (NOx) gas to nitrogen (N2) gas. Currently, most spent SCR catalyst in South Korea is eventually discarded in landfills. Recently, a novel and efficient recycling process has been developed to recover tungsten (W), vanadium (V) and titanium (Ti) from spent SCR catalyst. In this process, after soda-melting reactions between the spent SCR catalyst and sodium carbonate (Na2CO3) at 1273 K, hydrometallurgical treatments were carried out for the production of high-purity products, such as 99.3% sodium tungstate (Na2WO4), 99.3% vanadium oxide (V2O5) and 99.6% titanium dioxide (TiO2). On the basis of the fundamental investigation of this novel recycling process, process scale-up has been attempted to establish a commercial process. In this paper, recent developments in the recycling process for spent SCR catalyst and the results obtained using the scaled-up process will be discussed. Therefore, this study will provide a practical method for the recovery of W, V and Ti from spent SCR catalyst.
Highlights
Selective catalytic reduction (SCR) catalyst is used in power plants, incineration plants and vehicles for the conversion of nitrogen oxide (NOx ) gas to nitrogen (N2 ) gas
Among the several types of selective catalytic reduction (SCR) catalysts, vanadium pentoxide (V2 O5 )-tungsten trioxide (WO3 )/titanium dioxide (TiO2 ) catalyst is the most commonly used in industries owing to the high conversion rate of NOx gas, durability, sulfur endurance and wide temperature range for operation [4,5]
The results showed that TiO2 with a purity of 99.6–99.9% was obtained using a spent SCR catalyst
Summary
Selective catalytic reduction (SCR) catalyst is used in power plants, incineration plants and vehicles for the conversion of nitrogen oxide (NOx ) gas to nitrogen (N2 ) gas. This NOx gas is one of the major causes of particulate matter smaller than 2.5 micron (PM 2.5) that threatens public health [1,2]. Attention is drawn to the importance of the use of SCR catalyst and the volume installed will increase in the future. The compositions for the SCR catalyst are 0.5 mass %–1.5 mass % of V2 O5 , 7 mass %–10 mass % of WO3 Among the several types of SCR catalysts, vanadium pentoxide (V2 O5 )-tungsten trioxide (WO3 )/titanium dioxide (TiO2 ) catalyst is the most commonly used in industries owing to the high conversion rate of NOx gas, durability, sulfur endurance and wide temperature range for operation [4,5].
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