Abstract:

Ammonia selective catalytic reduction method (NH₃-SCR) is conducive to NO removal from diesel exhaust. In order to suit the conditions and temperature of diesel vehicle tail gas, a NH₃-SCR catalyst with graphene and TiO₂ composite support was prepared. The following conclusions were obtained through the catalytic activity evaluation of NH₃-SCR, XRD, SEM, BET and H₂-TPR characterizations. For TiO₂ supported catalyst, high content of Ce was beneficial to improve the catalytic activity of NH₃-SCR and widen the activity temperature range, while the active component Fe was helpful to its low temperature activity. For the graphene supported catalyst, the active component Ce had better catalytic activity, but Fe was more favorable to high temperature activity. For denitrification catalyst with TiO₂ and graphene composite supports, the catalytic activity temperature range was further widened and the powder phenomenon was improved in the catalyst reaction process, but the catalytic activity decreased slightly, among which Fe0.1Ce0.4Ti/10%GR catalyst had the best NH₃-SCR activity and NO conversion reached more than 90% in the temperature range of 220—450℃.

Key words: diesel exhaust, graphene, composite carrier, SCR, catalyst

摘要：

氨气选择性催化还原法有利于柴油车尾气中NO的脱除，为适合柴油车尾气条件和温度，制备一种石墨烯和TiO₂复合载体的脱硝催化剂，通过NH₃-SCR催化活性评价、X射线衍射（XRD）、扫描电子显微镜（SEM）、比表面积与孔隙度分析仪（BET）和程序升温还原（H₂-TPR）等表征得出以下结论：对于TiO₂载体催化剂，高含量的Ce有利于提高NH₃-SCR催化活性，并扩宽活性温度区间，活性组分Fe有利于其低温活性；对于石墨烯载体催化剂，活性组分Ce的催化活性更优越，但Fe更有利于高温活性；针对TiO₂和石墨烯复合载体脱硝催化剂，进一步扩宽了催化活性温度区间，改善催化剂反应过程中的粉化现象，但是催化活性略有下降，其中Fe0.1Ce0.4Ti/10%GR催化剂具有最优的NH₃-SCR活性，在220~450℃温度区间内NO转化率达到90%以上。

关键词: 柴油车尾气, 石墨烯, 复合载体, 选择性催化还原, 催化剂