One-pot synthesis of bimetallic CeCu-SAPO-34 for high-efficiency selective catalytic reduction of nitrogen oxides with NH3 at low temperature

Abstract

NH3 selective catalytic reduction (SCR) has been widely recognized as a promising technique for reducing nitrogen oxides from diesel vehicle exhausts. High-efficiency SCR catalysts that could perform at low temperatures are essential to denitration. In this work, a series of bimetallic CeCu-SAPO-34 molecular sieves were synthesized by one-step hydrothermal method. The CeCu-SAPO-34 maintained good crystallinity and a regular hexahedron appearance of Cu-SAPO-34 after introducing Ce species, while exhibiting a higher specific surface area and pore volume. The as-prepared CeCu-SAPO-34 with 0.02% (mass) Ce constituent exhibited the best catalytic activity below 300 oC and a maximum NOx conversion of 99% was attained; the NOx removal rates of more than 68% and 94% were achieved at 150 °C and 200 °C, respectively. And the introduction of cerium species in Cu-SAPO-34 improves the low-temperature hydrothermal stability of the catalyst towards NH3-SCR reaction. Additionally, the introduced Ce species could enhance the formation of abundant weak Brønsted acid centers and promote the synergistic effect between CuO grains and isolated Cu2+ to enhance the redox cycle, which benefit the NH3-SCR reaction. This work provides a facile synthesis method of high-efficiency SCR denitration catalysts towards diesel vehicles exhaust treatment under low temperature.