Effect of Sn(II)/Sn(IV) additive on the catalytic combustion of diethylamine and N₂ selectivity over CeZrO_x catalyst

The synthesis of CeZrSnOx by co-precipitation with different valence-state of Sn for diethylamine combustion is novel and intriguing. In this research, the Sn(II)/Sn(IV)-doped CeZrOx catalysts (CeZr(Sn)O-x-(Sn2+) and CeZr(Sn)O-x-(Sn4+)) were facilely prepared using the co-precipitation method, and their catalytic activities on destruction of diethylamine were evaluated. Detailed characterizations of the catalysts were conducted using X-ray photoelectron spectrometer (XPS), X-ray powder diffraction (XRD), hydrogen-temperature programmed reduction (H-2-TPR), temperature programmed ammonia desorption (NH3-TPD) and so on. For diethylamine combustion, CeZr(Sn)O-x-(Sn2+) showed higher activity and nitrogen selectivity than other catalysts, and a high conversion of diethylamine (>90 %) at 250 degrees C was obtained. After hydrothermal aging treatment, a high conversion (>90 %) and high N-2 selectivity maintained over CeZr(Sn)O-x-(Sn2+)-H at 280 degrees C, indicating high hydrothermal stability of CeZr(Sn)O-x-Sn2+. Owe to the large specific surface area (SSA), high oxygen mobility and strong redox performance, and the synergy between metal elements in CeZr(Sn)O-x-Sn2+ catalysts, the catalytic properties were enhanced. Moreover, Sn2+/Sn4+ ratio in the catalyst and strong acidic sites on the surface of the catalyst both had significant impacts on the catalytic activity and N-2 selectivity of the catalyst. Finally, the mechanism of diethylamine combustion over CeZr(Sn)O-x-Sn2+ was obtained by analyzing the reaction through in-situ diffuse reflection infrared Fourier-transform spectrum (in situ DRIFTS) test.