Abstract: A method for preparing 2,4-diaminophenol or 2,4-diaminophenol dihydrochloride comprising hydrogenation of 2,4-dinitrophenol on a membrane catalyst made of an alloy consisting of 90 to 98% by mass of palladium, 2 to 10% by mass of rhodium or ruthenium. Said hydrogenation of 2,4-dinitrophenol is effected by hydrogen diffusing through said membrane catalyst. The starting 2,4-dinitrophenol is used in a medium of water or a 4--37% aqueous solution of hydrochloric acid at a concentration of 2,4-dinitrophenol in said medium ranging from 2 to 50% by mass. The hydrogenation is effected at a temperature within the range of from 50.degree. to 150.degree. C. under a pressure of from 1 to 60 atm.

Abstract: A process for producing aniline, residing in a catalytic hydrogenation of nitrobenzene by using hydrogen in a gaseous phase at a temperature of from 20.degree. to 260.degree. C. and under atmospheric pressure, using a membrane catalyst which is essentially an alloy of palladium and ruthenium taken in a mass percent ratio of 88-98:12-2, respectively, permselective to hydrogen; hydrogenation being carried out by feeding nitrobenzene on the one side of the membrane catalyst and hydrogen, on the other side thereof. The process enables one to obviate purification of the end product from the residual catalyst and thereby to avoid losses of metals of the platinum group, as well as to effect hydrogenation under milder conditions without the formation of any by-products.