NOx removal by selective catalytic reduction with ammonia over hydrotalcite-derived NiTi mixed oxide
Abstract
Herein, a series of NiTi-LDHs were synthesized, calcined and tested in the removal of NOx by selective catalytic reduction with NH3 (NH3-SCR). Appropriate calcination temperatures as well as Ni/Ti molar ratios of LDH precursors were systematically identified to achieve optimal catalysis; the results pronouncedly affirmed that the catalytic performances of the as-acquired catalysts were vulnerable to the calcination temperature and Ni/Ti molar ratios, where the Ni4Ti1-400 catalyst presented optimal DeNOx activity (over 90% NOx conversion with nearly 95% N2 selectivity in the region of 240–360 °C), SO2 resistance and stability. Multiple characterization techniques revealed that the excellent catalytic performance of Ni4Ti1-400 could be attributed to the favorable interaction between the Ni and Ti species, consequently resulting in higher specific surface area, enhanced acidity, increased content of the surface Ni3+ species, and improved cycle reactions of NH3-SCR.