Guixian Deng,Guifang Zhang,Xing Zhu,Qingjie Guo,Xiangbiao Liao,Xi Chen,Kongzhai Li
Reduction of CO 2 in presence of oxidative impurity ( e.g. , O 2 ) is more promising than utilization of pure CO 2 due to skyrocketing cost for purification of captured CO 2 from air or industrial exhaust gas. In this work, Ni-based catalysts are modified by CeO 2 and ZrO 2 to suppress negative effect of O 2 on reforming of CO 2 with methane, which show high CH 4 conversion (97 %) and CO 2 conversion (95 %) at 750 °C and can maintain high CO 2 conversion even with high O 2 content. The physicochemical characterizations on fresh and spent catalysts show that the interaction among Ni, CeO 2 and ZrO 2 results in well dispersion of smaller Ni particles, even after long-term testing. In situ DRIFTS results show that Ni/CeO 2 -ZrO 2 -SiO 2 catalyst shows advantage to activate CH 4 to generate active CH 3 *, promoting the formation of CO, and the CeO 2 -ZrO 2 solid solution improves the CO 2 adsorption, thereby reducing the competitive effect of CO 2 and O 2 .
Effects of trace oxygen on iron sulphides-supported catalysts (FeS x /γ-Al 2 O 3 ) were evaluated through smelter off-gas reduction process for sulphur synthesis. Catalytic performance was evaluated under different oxygen content conditions. The properties of fresh and used catalysts were investigated by means of X-ray diffraction (XRD), thermogravimetry-differential thermal analysis (TG-DTA), X-ray photoelectron spectroscopy (XPS), and elemental analysis and relationships of active phases and activity were analyzed. The relationship between different active crystal crystals (FeS x , FeS 2 , Fe, FeO, γ-Fe 2 O 3 ) and SO 2 /O 2 adsorption and conversion was investigated. The mechanism of oxygen influence on the FeS x /γ-Al 2 O 3 surface was given and the lifetime of the catalyst in the reaction atmosphere close to real smelter off-gas after dust and oxygen removal steps containing trace oxygen (0.5 O 2 v/v.%) was explored.
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