镧改性Cu-SSZ-13分子筛用于氨选择性催化还原催化剂研究

STUDY ON LANTHANUM MODIFIED Cu-SSZ-13 MOLECULAR SIEVE AS NH3-SCR CATALYST

采用一步法制备出Cu-SSZ-13分子筛,然后用不同浓度的硝酸镧溶液对制备的分子筛进行离子改性,通过X射线衍射(XRD)、N2吸附-脱附(BET)、傅里叶变换红外光谱(FT-IR),H2程序升温还原(H2-TPR)、原位漫反射红外光谱(DRIFTS)等方法对催化剂进行表征,并评价其对氨选择性催化还原(NH3-SCR)过程的催化性能。结果表明:La0.015-Cu-SSZ-13催化剂的性能较Cu-SSZ-13有明显提高,其在175~450℃范围的NO转化率达到90%以上,具有较好的N2选择性;La改性Cu-SSZ-13的催化反应机理与Cu-SSZ-13类似,是通过表面氨物种和硝酸盐物种生成硝酸铵这一中间物种,然后硝酸铵被NO还原生成N2和H2O。

The Cu-SSZ-13 molecular sieve was prepared by one-step process and then modified by lanthanum nitrate solution with different concentration.The modified molecular sieve were used as a NH3-SCR catalyst and characterized by XRD,BET,FT-IR,TPR and DRIFTS techniques.The NH3-SCR reaction results showed that the performance of La0.015-Cu-SSZ-13 catalyst was significantly better than that of Cu-SSZ-13 catalyst,and the NO conversion rate on La0.015-Cu-SSZ-13 catalyst was more than 90%in the temperature range of 175-450℃with a good N2 selectivity.The NH3-SCR mechanism of La modified Cu-SSZ-13 is similar to Cu-SSZ-13 catalyst:ammonium nitrate,an intermediate species,is generated by surface ammonia species and nitrate species,and then ammonium nitrate is reduced by NO to generate N2 and H2O.