镧改性Cu-SSZ-13分子筛用于氨选择性催化还原催化剂研究

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。

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

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 of 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.