Catalytic activity of flame-synthesized Pd/TiO2 for the methane oxidation following hydrogen pretreatments--颗粒学报PARTICUOLOGY

Wang, N., Niu, F., Wang, S., & Huang, Y. (2018). Catalytic activity of flame-synthesized Pd/TiO2 for the methane oxidation following hydrogen pretreatments. Particuology, 41, 58-64. https://doi.org/10.1016/j.partic.2018.01.005

Catalytic activity of flame-synthesized Pd/TiO₂ for the methane oxidation following hydrogen pretreatments

Nafeng Wang ^a, Fang Niu ^b, Shuhao Wang ^a, Yun Huang ^a *

a State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
b Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing 100190, China

10.1016/j.partic.2018.01.005

Volume 41, December 2018, Pages 58-64

Received 11 October 2017, Revised 31 December 2017, Accepted 7 January 2018, Available online 11 June 2018, Version of Record 1 November 2018.

E-mail: yunhuang@ipe.ac.cn

Highlights

• Pd/TiO₂nanoparticles were synthesized by flame spray pyrolysis using a premixed stagnation flame.

• Optimal activity was obtained for Pd ratio of 53%, corresponding to lowest light-off temperature.

• Hysteresis in catalytic activity during heating–cooling cycle was affected by Pd oxidation state.

Abstract

A nanocatalyst composed of 10 wt% Pd supported on TiO₂ was synthesized using one-step flame spray pyrolysis with a highly-quenched premixed stagnation flame. The as-prepared nanoparticles, having a mean diameter of approximately 10 nm, were then subjected to isothermal oxidation and reduction in a fixed bed reactor. The potential roles of Pd and PdO as well as possible synergistic effects between these two active species were explored during methane conversion. The lowest light-off temperature T₂₀ was obtained at a Pd ratio of 53% and this result can be reasonably explained based on a surface Pd–PdO site pair mechanism. Additionally, differences in the hysteresis behavior during methane oxidation were noted throughout a heating–cooling cycle over the temperature range of 200–600 °C, such that the degree of hysteresis was strongly correlated with the Pd ratio.

Graphical abstract

Keywords

Catalytic oxidation; Palladium-based catalysts; Flame-assisted spray pyrolysis; Nanoparticles

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