Hydrogenation process for preparing 4-aminophenol

Abstract From the Canadian patent

The process for the production of 4-aminophenol by reducing nitrobenzene with hydrogen in a reaction zone at an elevated temperature and moderate pressure in the presence of aqueous sulfuric acid, a surfactant and a catalyst is improved by, using a platinum on carbon catalyst; utilizing a reaction zone which is not completely filled so that there is both a vapor space and a lower liquid space in the reaction zone and introducing the hydrogen into the vapor space part of said reaction zone; stirring the reaction mixture vigorously using an impeller placed at 40-60% of liquid depth to attain a rate of hydrogenation resulting in a performance index expressed as grams 4-aminophenol produced per …