A bifunctional catalytic system

Pt/SiO2 and a novel Brφ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.