A Novel One-Step Hydrothermal Preparation of Ru/SnxTi1−xO2 Diesel Oxidation Catalysts and its Low-Temperature Performance

Abstract

Abstract The rutile Sn x Ti 1− x O 2 ( x = 0, 0.33, 0.5, 0.67, 1) solid solution was synthesized by a one-step hydrothermal method, in which tetrabutyl titanate and Tin (IV) chloride pentahydrate were used as raw materials. A series of Ru/Sn x Ti 1− x O 2 were then prepared by the impregnation process in RuCl 3 to investigate the performance and stability of CO and C 3 H 8 oxidation. These catalysts were characterized through XRD, N 2 adsorption-desorption, FT-IR, TEM, XPS, H 2 -TPR, and O 2 -TPD techniques. The effect of Sn/Ti molar ratio and hydrothermal condition on the low-temperature catalytic oxidized performance and stability of Ru/Sn x Ti 1− x O 2 were investigated. The results indicated that Ru/Sn 0.67 Ti 0.33 O 2 catalyst showed an excellent activity and stability at low temperatures. The CO conversion reached 50% at 180 °C and 90% at 240 °C. Besides, the C 3 H 8 conversion reached 50% at 320 °C, the complete conversion of C 3 H 8 realized at 500 °C, and no deactivation occurs after 12 h of catalytic reaction. The excellent low-temperature activity and stability of the Ru/Sn 0.67 Ti 0.33 O 2 were attributed to the following factors. Firstly, XRD results showed that Sn 4+ was successfully introduced into the lattice of TiO 2 to replace Ti 4+ forming a homogeneous solid solution (containing –Sn 4+ –O–Ti 4+ – species), which was consistent with TEM and N 2 adsorption-desorption results. The introduction of Sn could suppress the growth of anatase crystal and promote the formation of rutile phase, and this phase transition was helpful to improve the low-temperature activity of the catalysts. Secondly, TEM images showed that ultrafine Ru nanoparticles (~ 5 nm) were dispersed on Sn 0.67 Ti 0.33 O 2 support, suggesting that the formation of Sn x Ti 1− x O 2 solid solution was beneficial to the dispersion of Ru particles.

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