Regulating Co Species over Co/SSZ-39 Catalyst to Enhance the Low-temperature CH4-SCR Activity
Co/SSZ-39 catalyst with different cobalt(Co)content was prepared by impregnation method and ion exchange method using small-pore SSZ-39 molecular sieve as carrier.The Co/SSZ-39 catalysts were characterized by X-ray diffraction(XRD),transmission electron microscopy(TEM),nitrogen adsorption-desorption and H2 tempera-ture programming reduction(H2-TPR).The effects of different preparation methods and catalysts with different Co loads on the performance of CH4 selective catalytic reduction of NO(CH4-SCR)were compared.The characterization results showed that the classification of Co species on SSZ-39 can be regulated by ion exchange method along with a single centrifuge washing.The Co/SSZ-39-S catalyst have both ionic Co sites and highly active CoOx species.The highly active CoOx species could promote moderate activation of CH4 at low temperature and improve the selective NOx reduction performance of CH4 at low temperature.When applied to CH4-SCR reaction,the catalyst prepared by this method can achieve 68%NO conversion and 82%CH4 conversion at a lower reaction temperature of 400℃(the molar ratio of NO and CH4 is 1∶1).When the molar ratio of NO and CH4 is 1∶2,the catalyst can achieve 76%NO conversion and 81%CH4 conversion,and the conversion rate remains stable within 50 h.The catalyst can realize the collaborative removal of NOx and CH4.
CH4-SCRCo/SSZ-39Low temperature activation of CH4Ion exchange method
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