Low-temperature NOx reduction over Cu-LTA and SmMnOx composite catalysts

Low-temperature selective catalytic reduction of NO_x with ammonia (NH₃-SCR) over zeolite catalysts remains a great challenge in diesel exhaust purification. Herein, Cu-LTA zeolite with excellent hydrothermal stability was composited with a small proportion of SmMnO_x oxides, the composite catalytic system efficiently resolves the low-temperature activity challenge encountered by Cu-LTA. The promoting pathways revealed the presence of active nitrite intermediates formed on SmMnO_x by activating NO, that were able to migrate to the Cu-LTA and can be further decomposed on the Brønsted acid sites. Compared to the continuous deposition of nitrates in Cu-LTA, the presence of SmMnO_x in composite catalysts efficiently reduced the accumulation of inert nitrate and improved the nitrate deposition phenomena. This innovative research would provide a rational strategy to break the barrier of limited low-temperature performance faced by zeolite catalysts, effectively promoting the NO_x removal in vehicles sources.