Zhu Donghong, Weng Xin, Tang Yuqiong, Sun Jingya, Zheng Shourong, Xu Zhaoyi
State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University Nanjing 210046 China
RSC Adv. 2020 Apr 7;10(24):14208-14216. doi: 10.1039/d0ra01578d. eCollection 2020 Apr 6.
Selective catalytic hydrogenation of -chloronitrobenzene on Pt-based catalysts is a green and high-efficient way for -chloroaniline production. However, supported monometallic Pt catalysts often exhibit undesirable -chloroaniline selectivity. We herein reported supported Pt catalysts with N-doped carbon (NC) as an overcoating (Pt/AlO@NC) to overcome the disadvantage. Three Pt/AlO@NC catalysts with different NC coating amounts were prepared by carbonization of an ionic liquid. For comparison, AlO coated by NC and Pt/AlO coated by SiO were also prepared. A combination characterization confirmed that the NC overcoating was successfully formed on Pt/AlO surface and Pt particles were completely coated by NC layers when ion liquid amount increased to 25 μl per g catalyst. Due to the intimate contact of NC layers and Pt particles Pt-NC heterojunctions were effectively formed on the catalyst surface. For the catalytic hydrogenation of -chloronitrobenzene, Pt/AlO@NC with 25 μl ionic liquid as the NC precursor exhibited 100% selectivity to -chloroaniline at 100% conversion of -chloronitrobenzene. A lower ionic liquid amount led to decreased selectivity to -chloroaniline. Furthermore, no deactivation was observed on Pt/AlO@NC during 5 catalytic cycles. The findings in the study demonstrate that coating noble metal catalysts by N-doped carbon is a promising method to enhance the selectivity and stability for catalytic hydrogenation of -chloronitrobenzene.
在铂基催化剂上对氯硝基苯进行选择性催化加氢是生产对氯苯胺的一种绿色高效方法。然而，负载型单金属铂催化剂通常表现出不理想的对氯苯胺选择性。我们在此报道了以氮掺杂碳（NC）作为包覆层的负载型铂催化剂（Pt/Al₂O₃@NC）以克服这一缺点。通过离子液体碳化制备了三种具有不同NC包覆量的Pt/Al₂O₃@NC催化剂。为作比较，还制备了用NC包覆的Al₂O₃和用SiO₂包覆的Pt/Al₂O₃。综合表征证实，当离子液体用量增加到每克催化剂25 μl时，NC包覆层成功地在Pt/Al₂O₃表面形成，并且Pt颗粒被NC层完全包覆。由于NC层与Pt颗粒的紧密接触，在催化剂表面有效地形成了Pt-NC异质结。对于对氯硝基苯的催化加氢反应，以25 μl离子液体作为NC前驱体的Pt/Al₂O₃@NC在对氯硝基苯100%转化时对对氯苯胺的选择性为100%。较低的离子液体用量导致对对氯苯胺的选择性降低。此外，在5次催化循环中未观察到Pt/Al₂O₃@NC失活。该研究中的发现表明，用氮掺杂碳包覆贵金属催化剂是提高对氯硝基苯催化加氢选择性和稳定性的一种有前景的方法。
