新型Pd7P3/SiC催化硝基苯加氢反应性能研究

Catalytic performance of a novel Pd7P3/SiC catalyst in nitrobenzene hydrogenation to make aniline

利用油胺还原的方法制备Pd7P3/SiC负载型催化剂,并考察其对硝基苯及其衍生物的加氢反应性能。通过TEM、XRD和XPS等分析手段对催化剂的形貌、晶体结构及电子状态等进行表征。结果表明,磷化钯纳米颗粒均匀分散在SiC载体上,化学组成为Pd7P3,粒径分布范围在6~9 nm。在相同催化条件下,负载量为2. 4%的SiC负载催化剂表现出最优的硝基苯加氢活性,在反应温度为40℃、初始压力为0. 5 MPa的条件下反应1 h,硝基苯的转化率达到99%以上,苯胺的选择性达到93%。而在同样的条件下,2. 4%的Pd7P3负载在活性炭上,硝基苯转化率仅有4%。说明磷化钯在载体上的形貌与电子状态的优化对其催化加氢性能有重要的促进作用。

Pd7P3/SiC catalyst is gained by the oleylamine reduction method and its catalytic performances for hydrogenation of nitrobenzene and derivatives are systematically investigated.The morphology,crystal structure and electronic state of the catalyst are characterized by transmission electron microscopy(TEM),powder X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS).The results show that the composition of palladium phosphide is Pd7P3,the particle size of palladium phosphide distributes in the range of about 6-9 nm,and the particles disperse uniformly on the surface of Si C.The Pd7P3/SiC catalyst with a loading amount of 2.4 wt%exhibits the best catalytic activity for hydrogenation of nitrobenzene,over which the conversion of nitrobenzene can exceed 99%and the selectivity of aniline can reach 93%when the hydrogenation reaction performs for 1 h at 40℃with an initial pressure of 0.5 MPa.Under the same conditions,the conversion rate of nitrobenzene can only achieve 4%over the catalyst that 2.4 wt%of Pd7P3 is loaded on activated carbon.It demonstrates the morphologies of palladium phosphide on the supporters and the optimization of electron state take important roles on the catalytic performance for dehydrogenation.