Effect of Zr-TiO₂ catalyst on NO emission from coal-burning and its catalytic mechanism

The effect of desulfurizer, modified TiO₂ prepared by different methods on the NO emission from inferior coal burning and the adaptability of coal type were studied by using a tube furnace. The prepared Zr-TiO₂ and the char were characterized by XRD, BET, SEM, XPS, TGA, and the mechanism of denitrification was explored. The results show that the addition of desulfurizer can promote NO emission. When the combustion temperature is 850 ℃, oxygen flow rate is 40 mL/min and the desulfurizer is MgO, the NO emission is the lowest as the catalyst of 5% Zr-TiO₂ prepared by impregnation method is added, which is 51.0% lower than that with addition of pure TiO₂ and 84.6% lower than that with pure coal under the same conditions. The catalyst 5% Zr-TiO₂ can be applied to the coal with sulfur < 3% and ash < 30%, having a wide application range. The doping of Zr can inhibit the growth of grain, enhance the active component, increase the content of adsorbed oxygen, promote the transformation of the valence states of the elements, accelerate the devolatilization of volatiles, promote the combustion, increase the specific surface area of chars, and enhance the ability of heterogeneous reduction of chars.