Modification of composite catalytic material CumVnOx@CeO2 core–shell nanorods with tungsten for NH3-SCR

Abstract

Novel composite material Cu_mV_nO_x-NF@Ce-MOF nanorods with a core–shell structure were successfully fabricated by the in situ growth of Ce-MOF on electrospun copper vanadate precursor nanofibers. Following calcination at 500, 600 and 700 °C, Cu₂V₂O₇@CeO₂, Cu₃(VO₄)₂@CeO₂ and Cu₁₁O₂(VO₄)₆@CeO₂, respectively, were obtained. The CeO₂ shell not only protected the copper vanadate nanofibers from breaking apart during the calcination process, but also induced an interaction between Ce, Cu and V species, which resulted in an excellent redox capacity. This revealed its potential as a catalyst for the selective catalytic reduction of nitrogen oxides with NH₃ (NH₃-SCR). Further surface modulation was accomplished by WO_x anchoring on the shell of Cu_mV_nO_x@CeO₂. According to a series of characterizations, the crystallinity of surface ceria on Cu_mV_nO_y@CeO₂-WO_x was apparently reduced and the amount of acid on its surface was also significantly increased. In addition, different calcination temperatures also had nonnegligible effects on the amount of surface acid as well as the redox capacity of the composite catalytic material Cu_mV_nO_y@CeO₂-WO_x. With the largest total quantity of acid sites as well as a suitable balance between acidity and reducing ability, the Cu₃(VO₄)₂@CeO₂-WO_x calcined at 600 °C exhibited satisfactory catalytic performance in the NH₃-SCR process, and the NO conversion could remain above 90% at 230–380 °C.