Direct synthesis of Cu-SAPO-34 from solid phosphorus source for NH3-SCR reaction

Abstract

Cu-SAPO-34 catalyst with CHA topology is widely used in the elimination of nitrogen oxides in automobile exhaust because of its excellent catalytic performance. A new method of directly synthesizing Cu-SAPO-34 from a new raw material instead of the original phosphorus source (phosphoric acid) was proposed. The new raw material AlPO4 can also act as an aluminum source in addition to serving as a phosphorus source. The two groups of samples took morpholine (MOR) and diethylamine (DEA) as templates respectively, and Cu-TEPA was used as Cu source to participate in the synthesis of the catalyst. The Cu-SAPO-34 catalysts had high NO conversion, and their activities were analyzed according to the characterization methods. The phase structure, active sites, strength of acid sites of Cu-SAPO-34 were analyzed by XRD, XPS, H2-TPR and NH3-TPD. In addition, the activity of directly synthesized Cu-SAPO-34 catalyst under different copper content and different template conditions was compared. The NO conversion of Cu0.05-SAPO-34-DT is 100% at 225–350 °C, while that of Cu0.05-SAPO-34-MT is more than 90% at 175–375 °C. As the raw material for direct synthesis of Cu-SAPO-34, AlPO4 not only reduces the synthesis cost, but also is more environmentally friendly.