氮掺杂碳材料中氮物种的调控及其负载Pd催化剂在加氢反应中的应用

Regulation of Nitrogen Species in Nitrogen Doped Carbon Materials and Its Hydrogenation Application Used as Supports for Pd Catalysts

介绍了氮掺杂碳材料中氮物种的调控方法,通过改变氮源添加量、氮源种类和焙烧温度能够对氮含量进行调控。通过原位合成法、后处理法以及改变反应条件(主要指焙烧温度和焙烧时间)能够对氮类型进行调控。原位合成法和后处理法制备的氮掺杂碳材料分别以石墨型氮和吡啶型氮为主。随着焙烧温度升高,焙烧时间延长,氮含量逐渐降低,石墨型氮占比上升。氮掺杂碳载体(N-C)负载Pd催化剂(Pd/N-C)在直接加氢和液相加氢脱氯反应中的应用方面,介绍了氮掺杂碳载体通过自身特性及其对Pd的锚定作用和电子影响来提高加氢性能,综合分析发现,氮掺杂碳载体增强了Pd/N-C催化剂与溶剂以及反应物的相互作用力;对Pd的锚定作用加强,提高了Pd/N-C催化剂的分散度和稳定性并改变了Pd0/Pd^(2+)的比例。

The methods of controlling nitrogen species in nitrogen doped carbon materials were introduced. The nitrogen content could be regulated by changing the amounts and types of nitrogen sources, and the calcination temperature. The nitrogen types could be regulated by in situ synthesis, post treatment and changing reaction conditions（mainly the calcination temperature and calcination time）. The nitrogen doped carbon materials prepared by in situ synthesis and post treatment were mainly graphitic nitrogen and pyridinic nitrogen. With the increase of calcination temperature and the extension of calcination time, the nitrogen content was gradually reduced, and the proportion of graphitic nitrogen increased. With respect to the applications of nitrogen doped carbon materials（N-C） used as supports for Pd catalysts（Pd/N-C） in the direct hydrogenation and liquid phase hydrodechlorination reactions, the article described that nitrogen doped carbon supports improved their hydrogenation performance through their own properties and their anchoring effect on Pd and electronic effects. Comprehensive analysis found that nitrogen-doped carbon carriers enhanced the interactions among Pd/N-C catalysts, solvent and reactants. The anchoring effect on Pd was strengthened, the dispersion and stability of Pd/N-C catalysts were improved and the ratio of Pd0/Pd2＋ was changed.