A [Cu2O2]2+ Core in Cu/ZSM-5 for Efficient Selective Catalytic Oxidation of Nitrogen-Containing VOCs and NH3

Highly efficient elimination of nitrogen-containing volatile organic compounds (NVOCs) or NH3 via selective catalytic oxidation (SCO) while avoiding NOx is a strongly desired process for their control. However, limited by a lack of fundamental guidance such as accurate active site and reaction mechanisms, the targeted design of high-performance catalysts faces severe challenges. Herein, ZSM-5 zeolites supported by different copper species were used in the SCO of dimethylformamide (DMF) and NH3. Optimal 8% Cu/ZSM-5 had the highest N-2 selectivity of above 94%. Various in situ spectroscopic characterizations and DFT theoretical calculations precisely identified that the active site is a mu-(eta(2):eta(2))-peroxo dicopper (bent; [Cu2O2](2+)) core, which is associated with two Al sites separated by three SiO4 tetrahedra units in the 10-membered ring of ZSM-5. The dynamic catalytic behavior of DMF-SCO was revealed to be that [Cu2O2](2+) transformed into mono-(mu-oxo) dicopper upon DMF adsorption, while the opposite process occurred when O-2 attacked. In situ DRIFTS elucidated the DMF-SCO reaction pathway and indicated that the disassociating N-H bond was the rate-determining step in transforming DMF to N-2. This work not only strongly points the way to the design of high-performance catalysts of NVOCs and NH3 elimination but provides methodological implications for in situ study of active sites and their dynamic structures.