活性炭负载Pt-Fe双金属催化剂催化对氯硝基苯选择性加氢

采用浸渍还原法制备了活性炭负载Pt-Fe双金属催化剂(Pt-Fe/AC),考察了其催化对氯硝基苯加氢性能。 与Pt/AC催化剂比较,该催化剂对催化对氯硝基苯加氢表现出高活性和优异的抑制脱氯性能,在乙醇为溶剂、催化剂Pt_0.003-Fe_0.04/AC(下标为元素在催化剂中的质量分数)用量为0.02 g/g对氯硝基苯、1 MPa H₂和30 ℃条件下反应150 min,对氯硝基苯完全转化为对氯苯胺,而且即使在较高的反应温度和H₂压力下,脱氯反应也得到了完全抑制。 采用X射线衍射(XRD)、透射电子显微镜(TEM)及X射线光电子能谱(XPS)等技术手段对Pt-Fe/AC催化剂进行了表征。 结果表明,Pt、Fe高度分散在活性炭上,Pt与Fe之间的相互作用对纳米Pt粒子的电子结构有一定的调变作用,使纳米Pt处于缺电子态,减弱了Pt与对氯苯胺苯环之间的电子反馈,这可能是Pt-Fe/AC对催化对氯硝基苯加氢表现出高活性和优异的抑制脱氯性能的主要因素。

Selective Hydrogenation of p-Chloronitrobenzene Catalyzed by Activated Carbon Supported Fe-Pt Bimetallic Catalyst

An activated carbon supported Pt-Fe bimetallic catalyst (Pt-Fe/AC) was prepared by impregnation reduction method, and its catalytic performance for selective hydrogenation of p-chloronitrobenzene (p-CNB) to p-chloroaniline (p-CAN) was investigated. Compared with Pt/AC catalyst, the Pt-Fe/AC catalyst exhibited higher activity and excellent inhibition of dechlorination. One hundred percent selectivity towards p-CAN at complete conversion of p-CNB was achieved under the following conditions: 30 ℃ for 150 min, 1.0 MPa H₂, ethanol as solvent, and 0.02g Pt_0.003-Fe_0.04/AC catalyst(the lower case numbers represent the mass fraction of related metal in the catalyst) per gram p-CNB. The high selectivity towards p-CAN remained even at high temperature and H₂ pressure. The as-prepared catalysts were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The results show that Pt and Fe are well dispersed on the AC surface. The higher activity and excellent selectivity of the Pt_0.003-Fe_0.04/AC are primarily derived from the electron-deficient state of Pt due to the electronic effect of Pt nanoparticles with Fe, which weakened the extent of electron feedback from Pt particles to the aromatic ring of p-CAN and suppressed the hydrodechlorination of p-CAN.