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

Abstract

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)Ox-(Sn2+) and CeZr(Sn)Ox-(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 (H2-TPR), temperature programmed ammonia desorption (NH3-TPD) and so on. For diethylamine combustion, CeZr(Sn)Ox-(Sn2+) showed higher activity and nitrogen selectivity than other catalysts, and a high conversion of diethylamine (>90 %) at 250 °C was obtained. After hydrothermal aging treatment, a high conversion (>90 %) and high N2 selectivity maintained over CeZr(Sn)Ox-(Sn2+)-H at 280 °C, indicating high hydrothermal stability of CeZr(Sn)Ox-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)Ox-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 N2 selectivity of the catalyst. Finally, the mechanism of diethylamine combustion over CeZr(Sn)Ox-Sn2+ was obtained by analyzing the reaction through in-situ diffuse reflection infrared Fourier-transform spectrum (in situ DRIFTS) test.