Abstract
Utilizing mechanochemical interactions to fabricate hybrid catalysts composed of two or more materials is an important emerging area in heterogeneous catalysis. Here, we report unusual deactivation of vanadia catalyst derived from mechanical grinding with Al-rich zeolite, initially designed to overcome the ammonium bisulfate poisoning in low-temperature selective catalytic reduction (SCR) of NO_x. Various characterizations reveal that mechanical force applied to zeolite imparts mobility to extra-framework AlO_x moieties. Some of the diffused AlO_x species bound to VO_x sites lower reducibility of catalyst, degrading its initial performance. These phenomena are effectively resolved by novel strategy of covering the surface of zeolite with a thin carbon layer, suppressing the diffusion of AlO_x moieties during grinding. The hybrid catalyst prepared by tailoring mechanochemical interaction demonstrates superior sulfur resistance in low-temperature (180 °C) SCR operation. Our study critically describes effects of mechanical forces on catalytic properties and efficient modulation of these interactions through surface functionalization.
NSTL