In situ regeneration of sulfated Cu/SAPO-34 catalyst for the selective catalytic reduction of NOx with NH3.

The regeneration mechanism of sulfated Cu/SAPO-34 catalysts in reducing atmospheres (5% H₂/Ar and NH₃/Ar at 600 °C) was investigated by using a series of characterization methods. Hydrogen regeneration improved the catalysts' NH₃-SCR activity from 150 to 550 °C remarkably, while ammonia regeneration exhibited relatively less obvious promotion effect. The TPR of hydrogen and EPR spectra data show that the regeneration process affects the amount and the coordination of the active isolated Cu²⁺ species significantly. The desulfation increases the amount of isolated copper ions and improves the catalytic activity of SCR. [ABSTRACT FROM AUTHOR]