Boosting NH3-SCR of NOx performance through sustainable and economical synthesis of Cu-SAPO-34 zeolites from attapulgite†

Abstract

Small-pore Cu-SAPO-34 zeolites have been intensively studied for the selective catalytic reduction of nitrogen oxides (NO_x) with NH₃. However, the prohibitive cost of conventional synthesis has limited their widespread industrial application. Herein, nanosized Cu-SAPO-34-ATP has been synthesized from attapulgite (ATP) by a hydrothermal method, which is a green and economical route. The synthesized nanosized Cu-SAPO-34-ATP zeolites possess high crystallinity, uniform cubic morphology, enhanced acid sites, and abundant Cu-active species. The nanoscale architecture of Cu-SAPO-34-ATP catalysts significantly improves mass transport properties due to substantially reduced diffusion pathways. Consequently, compared to conventional Cu-SAPO-34, the Cu-SAPO-34-ATP zeolites exhibit excellent low-temperature NH₃-SCR activity, along with enhanced hydrothermal stability. Notably, over the Cu_0.05-SAPO-34-ATP catalyst more than 90% NO_x conversion is achieved in the temperature range from 215 °C to 535 °C. These results highlight the potential of nanosized Cu-SAPO-34 derived from ATP as a next-generation deNO_x catalyst, combining environmental and resource-recycling advantages. This study also offers insights for designing innovative nanocatalysts for air pollution control.