铜源对Cu-SAPO-34氨催化还原NO性能的影响

采用离子交换法制备3种不同铜前驱体的Cu-SAPO-34分子筛催化剂,考察铜源对催化剂氨催化还原NO_x性能的影响,同时通过ICP、XRD、BET、H_2-TPR、XPS、NH_3-TPD等表征技术进行分析.活性结果表明,不同铜源制备的Cu-SAPO-34分子筛催化剂的NH_3-SCR高温活性基本相同,但中低温活性有较大差别.3种催化剂的中低温活性顺序为Cu(醋酸铜)-SAPO-34Cu(硫酸铜)-SAPO-34Cu(硝酸铜)-SAPO-34,以醋酸铜为铜源制备的催化剂中低温活性最高,在209℃NO_x转化率达85.2%.表征结果表明,不同铜源导致所制备催化剂的铜物种形式和数量及酸性强度不同,以醋酸铜为铜源制备的Cu-SAPO-34催化剂的Cu~(2+)起始还原温度最低,Cu~(2+)含量较多,酸性最强,因此其中低温活性最好.

Effects of Copper Sources on Selective Catalytic Reduction of NO with NH3 of Cu-SAPO-34

Three kinds of Cu-SAPO-34 zeolite catalysts with different copper precursor were prepared by ion-ex-change method,their catalytic performance in selectively catalytic reduction of NOx with NH3 were investigated and analyzed by ICP,XRD,BET,H2-TPR,XPS,NH3-TPD,among other characterization technologies.The results showed that the activity of Cu-SAPO-34 catalysts prepared with different copper source had little change when the temperature was high,but there were significant difference at medium and low temperature.The activity order of those catalysts at medium and low temperature were as follows:Cu(copper acetate)-SAPO-34 >Cu(copper sul-phate)-SAPO-34 >Cu(copper nitrate)-SAPO-34.The best medium and low temperature catalyst activity was Cu-SAPO-34 catalyst with copper acetate as copper source,its conversion of NOx reached 85 .2%at 209 ℃.Charac-terization results indicated that catalysts with different copper sources showed different copper species forms and number of copper species and acid strength.The reason why catalyst made by copper acetate as copper source demonstrated the best activity at medium and low temperature was that the original reduction temperature of Cu2+was the lowest,the content of Cu2+was high enough and the acidity was the strongest.