Fluidized bed plasma for pre-treatment of Co-ferrierite catalysts: An approach to NOx abatement

Replacement of calcination procedures used during catalyst preparation, by a plasma treatment, was studied over a Co-ferrierite (Co-FER) catalyst. The catalyst was tested in the NOx selective catalytic reduction reaction. A combination of UV–Vis spectroscopy and TG analysis revealed the presence of ammonium ions on the untreated and plasma Co-FER samples but not on the calcined one. Therefore, it can be concluded that the plasma treatment was not able to replace the thermal calcination step. The evaluation of catalyst behaviour was performed both under temperature programmed surface reaction (TPSR) and under steady-state conditions at different temperatures. NO oxidation tests showed that, during TPSR runs, calcined catalyst produces more NO2 than plasma catalyst. NOx consumption during TPSR of plasma catalyst confirms that precursors used on the ion-exchange procedure are still present on the catalyst even after the plasma treatment, reacting with NO to produce R-NOx, N2O and N2. Concerning deNOx tests using ethanol as reducing agent, TPSR tests showed higher NOx conversions over untreated and plasma catalysts due to the presence of ammonium and acetate precursors on these catalysts. Untreated, plasma and calcined catalysts present the same NOx and COx conversions in isothermal tests.