FT-IR operando study on selective catalytic reduction of NO_x species by ammonia:A comparison between zeolitic and GAPON compounds

摘要

Zeolitic materials are currently studied as potential catalysts for NO_x SCR using ammonia as reducing agent.It was recently evidenced that a higher activity can be reached when an appropriate ratio between NO and NO_2 is reached in the flow.To obtain this composition,oxidation catalysts are used in addition to the zeolitic compound.Nevertheless,the oxidation catalyst is easily poisoned by the SO_2 normally present in a real flow.The use of an acidic material to prevent the SO_2 effect and containing an oxidising function seems to be a very good alternative to improve the efficiency of the SCR process.Therefore,we have tested the possibility to perform such kind of reaction in two ammonium galloposphates (representing nanoporous compounds alternative to zeolites),containing transition elements in the crystal structure.The study has been carried out in real temperature and VHSV conditions using an IR transmission reactor cell coupled with a gas analysis system constituted by a IR gas cell and a mass spectrometer.The different analyses are performed on line,under flow,at the time resolution of 1 s.