The promotion effect of Cu on the V/WTi catalyst for the selective catalytic reduction of NO_x by NH₃ was investigated in the temperature range of 150–400 °C.

The effects induced by SO ₂ on Pt/Al ₂ O ₃ catalysts were studied as a function of SO ₂ exposure time, and NO oxidation activity was investigated for different treated Pt/Al ₂ O ₃ catalysts. The mechanism of Pt/Al ₂ O ₃ poisoned by SO ₂ and regenerated by NO oxidation is expected.

To reveal the role of impregnated sodium (Na) ions in Cu/SSZ-13 catalysts, Cu/SSZ-13 catalysts with four Na-loading contents were prepared using an incipient wetness impregnation method and hydrothermally treated at 600 °C for 16 h. The physicochemical property and selective catalytic reduction (SCR) activity of these catalysts were studied to probe the deactivation mechanism. The impregnated Na exists as Na⁺ on catalysts and results in the loss of both Brönsted acid sites and Cu²⁺ ions. Moreover, the high loading of Na ions destroy the framework structure of Cu/SSZ-13 and forms new phases (SiO₂/NaSiO₃ and amorphous species) when Na loading was higher than 1.0 mmol/g. The decreased Cu²⁺ ions finally transformed into Cu_xO, CuO, and CuAlO_x species. The inferior SCR activity of Na impregnated catalysts was mainly due to the reduced contents of Cu²⁺ ions at kinetic temperature region. The reduction in the amount of acid sites and Cu²⁺ ions, as well as copper oxide species (Cu_xO and CuO) formation, led to low SCR performance at high temperature. Our study also revealed that the existing problem of the Na ions’ effect should be well-considered, especially at high hydrothermal aging when diesel particulate filter (DPF) is applied in upstream of the SCR applications.

A series of Pd/BEA catalysts with various Pd loadings were synthesized. Two active Pd²⁺ species, Z⁻-Pd²⁺-Z⁻ and Z⁻-Pd(OH)⁺, on exchanged sites of zeolites, were identified by in situ FTIR using CO and NH₃ respectively. Higher NO_x storage capacity of Z⁻-Pd²⁺-Z⁻ was demonstrated compared with that of Z⁻-Pd(OH)⁺, which was caused by the different resistance to H₂O. Besides, lower Pd loading led to a sharp decline of Z⁻-Pd(OH)⁺, which was attributed to the ‘exchange preference’ for Z⁻-Pd²⁺-Z⁻ in BEA. Based on this research, the atom utilization of Pd can be improved by decreasing Pd loading.