铜前驱体对Cu/SSZ-13催化剂NH3选择催化还原NO性能的影响

Effects of Copper Precursors on Catalytic Performance of Cu/SSZ-13 Catalyst for NH;Selective Catalytic Reduction of NO

采用离子交换法,分别以乙酸铜、氯化铜、硝酸铜和硫酸铜为前驱体制备了4种铜物种含量几乎相同的Cu/SSZ-13分子筛催化剂。探究了前驱体对NH_(3)选择性催化还原NO(NH_(3)-SCR)的影响,并通过XRD,ICP,N_(2)吸-脱附,SEM,H_(2)-TPR,XPS,NH_(3)-TPD等表征分析方法对样品的物化性质进行了探究。催化活性结果表明,铜前驱体对Cu/SSZ-13分子筛中低温范围的氨选择性催化还原性能具有显著差异。其中催化剂起燃温度T50(转化率≥50%时的温度)的高低顺序为Cu(乙酸铜)/SSZ-13<Cu(氯化铜)/SSZ-13<Cu(硫酸铜)/SSZ-13<Cu(硝酸铜)/SSZ-13。表征结果表明,铜前驱体会影响分子筛催化剂中铜物种的分布和数量以及酸性。以乙酸铜为前驱体制备的Cu/SSZ-13催化剂具有最多的孤立Cu^(2+)以及强L酸位数量,有助于样品低温段NH_(3)-SCR催化反应的进行.

Cu/SSZ-13 catalysts with the nearly same contents of copper species were prepared by ion exchange technology with copper acetate,copper chloride,copper nitrate and copper sulfate as precursors.The effects of copper source on NH_(3) selective catalytic reduction(NH_(3)-SCR)were probed detailedly.The physicochemical properties of the catalysts were investigated by XRD,ICP,N_(2) absorption-desorption,SEM,H_(2)-TPR,XPS and NH_(3)-TPD.The results of activity test display that the performance of Cu/SSZ-13 zeolite for ammonia selective catalytic reduction at low temperature is significantly different.The light off temperature T50(the temperature when conversion efficiency≥50%)follows the order of Cu(copper acetate)/SSZ-13<Cu(copper chloride)/SSZ-13<Cu(copper sulfate)/SSZ-13<Cu(copper nitrate)/SSZ-13.The characterization results manifest that the distribution and quantity of copper species and the acidity of zeolite catalysts are affected by copper source.The Cu/SSZ-13 catalyst prepared with copper acetate as precursor possesses the largest number of isolated Cu^(2+)and strong L acid sites,which are conducive to the low-temperature NH_(3)-SCR reaction.