Synthesis and characterisation of monolithic PTFE-modified MnOX/FeOX catalysts for selective catalytic reduction (SCR) of NOX at low temperature

BACKGROUND Selective catalytic reduction (SCR) of NOX has been the most widely used technique for the reduction of NOX emissions from combustion flue gas. MnOX/FeOX based catalysts typically can attain high NOX conversion at low temperature but with inferior water vapor resistance. RESULTS A MnOX/FeOX catalyst was synthesized by the sonicated co-precipitation method and then wash-coated on ceramic cordierite monoliths to form a low pressure drop monolithic catalyst suitable for high flowrate flue gas treatment conditions. The catalyst achieved above 90% NO conversion at a gas hourly space velocity (GHSV) of 30 000 h(-1) over a 125-225 degrees C temperature window under simulated industrial flue gas conditions. In the presence of up to 5% H2O vapor, comparable performance was retained for a reduced temperature window of >= 150 degrees C. In order to improve water resistance and LT-SCR performance, an optimal 10% w/w polytetrafluoroethylene (PTFE) doped MnOX/FeOX catalyst was developed, which exhibited remarkably high performance of up to 98% NO conversion, with improved water resistance at up to 10% v/v H2O while retaining high performance from 100 degrees C. CONCLUSION Monolithic MnOX/FeOX catalyst incorporating PTFE significantly improved NO conversion and water vapour resistance due to the enhanced NH3 adsorption associated with Lewis acid sites and water repellent property. These findings will provide guidance for researchers in this field to adapt F-based or similar additives into the making of high performance and high water resistance catalysts either to retrofit existing catalyst synthesis procedures or reinvent a novel catalyst in a scalable but economical way. (c) 2020 Society of Chemical Industry

Automated summary

A MnOX/FeOX catalyst was developed for high NO conversion in industrial flue gas conditions, with over 90% conversion achieved in a temperature range of 125-225°C. Addition of PTFE improved water vapor resistance and further enhanced NO conversion, reaching up to 98% conversion with up to 10% water vapor present.