Under practical NH3-SCR (selective catalytic reduction) condition, Cu-SSZ-13 catalyst undergoes hydrothermal aging as well as sulfur poisoning. In this study, an attempt was made to study/distinguish unique responses of Cu2+ and [CuOH]+ as the main SCR active centers to SO2 poisoning. Two Cu-SSZ-13 model catalysts were prepared with different Si:Al ratios to obtain two opposite distribution of Cu2+ and CuOH+. Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES), H2 Temperature programmed reduction (H2-TPR) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) were used to quantify amount of Cutot and Cu2+ and [CuOH]+. Micro-reactor experiments were then carried out to capture S storage, desorption, poisoning as well as regenerations on two model catalysts. It was found that SO2 poisoning in Cu-SSZ-13 is site specific. In terms of adsorption and desorption behavior of S, it was found that depending on the active center, S can either form ammonium sulfate or copper sulfate resulting in different temperature treatment required for their regenerations. A detailed mechanism for S poising in Cu-SSZ-13 is then proposed with the consideration of two different active sites.

Mechanistic study of S poising in Cu-SSZ-13: Responses of Cu2+ and CuOH active centers to SO2 exposure

254th National Meeting (2017)

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