【摘要】 采用混合醇还原法制备了聚乙烯吡咯烷酮 (PVP)稳定的Ru Pt/γ Al2 O3 双金属催化剂 ,考察了其催化对氯硝基苯(p CNB)选择加氢反应的性能 ,探讨了反应温度、压力、第三金属离子的种类、添加量及添加方式对反应的影响 .结果表明 ,以Ru Pt/γ Al2 O3 为催化剂 ,在 1 0MPa和 5 0℃的条件下反应 1h ,p CNB的转化率可达 4 8 2 % ,生成对氯苯胺 (p CAN)的选择性为 87 3% .在反应体系中添加适量的Fe3 + 或Sn4+ 离子时 ,在相同的反应条件下 ,p CNB的转化率和 p CAN的选择性分别提高到 10 0 %和 99 0 % .Fe3 + 或Sn4+ 的添加量及添加方式对 p CNB的转化率有较大的影响 ,加入Fe2 + ,Co2 + 和Ni2 + 离子也有利于提高催化剂的活性和选择性 .Ru Pt/γ Al2 O3 催化剂体系对其它氯硝基苯的加氢反应也有明显的催化作用 .更多还原

【Abstract】 The bimetallic catalyst Ru-Pt/ γ-Al 2O 3 was prepared by impregnating γ-Al 2O 3 with aqueous solution of H 2PtCl 6 and RuCl 3 in the presence of PVP-40000. The influence of reaction temperature, pressure and the addition of metal cations on the selective hydrogenation of p-chloronitrobenzene (p-CNB) over Ru-Pt/ γ-Al 2O 3 was investigated. The catalytic activity of Ru-Pt/ γ-Al 2O 3 was much higher than that of Ru/ γ-Al 2O 3 , while aniline and other by-products over Ru-Pt/ γ-Al 2O 3 were obviously less than those over Pt/ γ-Al 2O 3 . There was a synergistic effect between Ru and Pt in the bimetallic catalyst. The catalytic performance of Ru-Pt/ γ-Al 2O 3 could be remarkably enhanced by the addition of metal cations. Ru-Pt/ γ-Al 2O 3 catalyst modified by Sn 4+ and Fe 3+ exhibited excellent activity and selectivity in p-CNB hydrogenation. Under the conditions of n(substrate) / n(Ru+Pt) = 1*!000 , p(H 2) =1.0 MPa and 50 ℃, the conversion of p-CNB and the selectivity for p-chloroaniline (p-CAN) could reach 100% and 99.0% in 1 h, respectively. When Fe 2+ , Co 2+ and Ni 2+ were used to modify the Ru-Pt/ γ-Al 2O 3 catalyst, the conversion of p-CNB rose from 48.2% to 86%, 74.5% and 87.8%, and the selectivity for p-CAN increased from 87.3% to 98.6%, 98.9% and 99.4%, respectively. However, Zn 2+ and Sn 2+ were poisons for the Ru-Pt/ γ-Al 2O 3 catalyst. The Ru-Pt/ γ-Al 2O 3 catalyst modified by Sn 4+ also exhibited high activity and selectivity for the hydrogenation of other chloronitrobenzenes.更多还原