【摘要】 针对硝基苯催化加氢合成对氨基苯酚(PAP)的过程,提出了Pt/SiO2和新型季铵型Brφnsted酸性离子液体N,N,N-三甲基-N-磺丁基硫酸氢铵([HSO3-b-N(CH3)3]HSO4)构成的双功能催化体系。考察了离子液体浓度、Pt/SiO2用量及操作条件对对氨基苯酚收率和选择性的影响。并与硫酸体系进行了对比。在85℃、4h、0.4 MPa条件下,硝基苯转化率96.6%,对氨基苯酚的选择性为81.4%,优于Pt/SiO2和硫酸溶液体系。可能的原因是,离子液体增加了硝基苯溶解度,并且抑制了中间产物苯基羟胺的深度加氢。反应后用减压过滤可分离出Pt/SiO2催化剂;滤液经由萃取、减压蒸馏和结晶析出PAP。结果证明,该双功能催化体系重复使用3次,PAP收率没有明显的下降。更多还原

【Abstract】 A bifunctional catalytic system,Pt/SiO2 and a novel Brnsted acidic ionic liquid of quaternary ammonium type N,N,N-trimethyl-N-sulfobutyl hydrogen sulfate([HSO3-b-N(CH3)3]HSO4) was studied for the synthesis of p-aminophenol through the hydrogenation of nitrobenzene.The effect of ionic liquid concentration,amount of Pt/SiO2 and reaction conditions on the p-aminophenol yield and selectivity was investigated,and was compared with the result obtained over H2SO4 and Pt/SiO2 catalytic system.Under the reaction conditions of 85℃,4 h and 0.4 MPa,nitrobenzene conversion was 96.6% and p-aminophenol selectivity was 81.4% over Pt/SiO2 and [HSO3-b-N(CH3)3]HSO4,superior to the results over Pt/SiO2 and H2SO4.The possible reasons were the enhancement of nitrobenzene solubility influenced by ionic liquid,and the restriction of deep hydrogenation for phenylhydroxylamine.Pt/SiO2 catalyst could be recovered by filtration in vacuum,and p-aminophenol could be obtained from the filtrate by extraction,vacuum distillation and crystallization in sequence.Moreover,the ionic liquid and Pt/SiO2 catalytic system could be used for three times without obvious decrease of p-aminophenol yield.更多还原