The Hydrogenation Of Nitrobenzene In The CO₂/H₂O System Using Lindlar-Pd To Synthesize P-aminophenol

In this dissertation, CO2/H2O system employing Lindlar catalyst is developed for the preparation of p-aminophenol (PAP) from selective catalytic reduction of nitrobenzene (NB). On the one hand, CO2/H2O system is the optimum substitution for the conventional acid which provides acidic medium for Bamberger rearrangement, besides, the system is self-neutralized by releasing CO2with no need of base. On the other hand, the commercial Lindlar catalyst is choosed to prepare PAP from reduction of NB which realizes the higher selectivity and benefits to the industrial application of this reaction process.In this work, two kinds of Lindlar catalysts with different poison treatments (Pd-Pb/CaCO3,5wt.%, Pd-Quinoline/BaSO4,5wt.%) were used. The effect of different reaction parameters on the preparation of PAP from selective catalytic reduction of NB were stuied when any one of the Lindlar catalysts was choosen. And the optimum reaction conditions were confirmed as:1) Pd-Pb/CaCO3as catalyst, NB5mmol, cat.6.4mg (nNB:nPd=1600:1), H2O60mL, r=1500r/min,140℃, initial pressure PH20.3MPa, initial pressure PCO24.0MPa,8h, the conversion of NB was75%, the yield and selectivity of PAP were49%and64%, respectively.2) Pd-Quinoline/BaSO4as catalyst, NB5mmol, cat.10.6mg (nNB:npd=1000:1), H2O60mL, r=1500r/min,140℃, reaction pressure Ph20.7MPa, initial pressure PCo24.0MPa,5h, the conversion of NB was99%, the yield and selectivity of PAP were68%and75%, respectively.