Tailored temperature window of CuOx/WOx–ZrO2 for NOx reduction via adjusting the calcination temperature of WOx–ZrO2

WOx–ZrO2 support was calcined at various temperatures for obtaining controllable activity of copper catalysts for NOx reduction by ammonia. The temperature window of copper catalyst for over 80% NOx conversion shifts from 180–300 to 230–350 °C by elevating the calcination temperature of WOx–ZrO2 support from 500 to 600 °C, due to the increased Brønsted acidity and reduced structure and electronic interactions between copper oxides and tungsten oxides arising from the polymerization of WOx clusters on surface of support. Calcining WOx–ZrO2 support at 700 °C leads to the reduced redox property of copper oxides on the Cu–O–W interface and the formation of bulk-like CuO, results in a low activity of catalyst.