Sustainable preparation of highly efficient copper ferroaluminosilicate CHA zeolite for selective catalytic reduction of NOx with NH3

Abstract

Copper aluminosilicate CHA zeolite has been widely applied in selective catalytic reduction of NOx with NH3 (NH3-SCR), but the formation of CuOx clusters in the zeolite catalyst strongly influence the catalytic activity at the relatively high temperatures. In this work, we have employed the coal fly ash (CFA) as a starting source for one-pot synthesis of CHA zeolite. Because the CFA contains Fe, Al, and Si species, it is finally obtained copper ferroaluminosilicate CHA zeolite (Cu/Fe-Al-CHA). Interestingly, the introduction of Fe species in the Cu/Fe-Al-CHA zeolite significantly hinders the formation of CuOx clusters in the aged zeolite catalyst, compared with a conventional Cu/Al-CHA zeolite. As a result, the activities at the temperatures of 350–450 °C in NH3-SCR over the Cu/Fe-Al-CHA zeolite is a little higher than those over the conventional Cu/Al-CHA zeolite. Characterizations of the samples show that the presence of Fe species in the CHA framework results in shifts of Cu species to high energies, compared with the conventional Cu/Al-CHA zeolite. These results mean that there are stronger interactions between Cu species and Cu/Fe-Al-CHA zeolite framework than those between Cu species and Cu/Al-CHA zeolite framework. Because the starting source is the CFA, a solid waste in the environment, it can be regarded as a sustainable preparation of highly efficient Cu/Fe-Al-CHA zeolite catalysts, which might offer a new opportunity to prepare highly efficient zeolite-based catalysts with an environmentally friendly manner.