One object of the invention is a process for the catalytic hydrogenation of aromatic nitro compounds in solution or in melt in the presence of hydrogen and at least one noble metal catalyst, nickel catalyst or cobalt catalyst, in which process a catalytic amount of at least one vanadium compound is present, wherein the vanadium has the oxidation state 0, II, IV or V. It has been found that in the catalytic hydrogenation of aromatic nitro compounds the accumulation of hydroxylamines can be almost completely prevented by the addition of catalytic amounts of vanadium compounds, which usually results in concentrations of <1% hydroxylamine. The resulting hydrogenated products are whiter (purer) than those obtained without the addition of the vanadium compound because almost no azo or azoxy compounds are obtained. The hydrogenation, in particular the final phase, proceeds faster than without said addition. Accordingly, substantial advantages with respect to quality constancy and economy are obtained.
                            本发明的一个目标是在存在
氢气和至少一种
贵金属催化剂、
镍催化剂或
钴催化剂的情况下,在溶液或熔融状态下催化氢化芳香族
硝基化合物的过程中,存在至少一种
钒化合物的催化量,其中
钒的氧化态为0、II、IV或V。已经发现,在芳香族
硝基化合物的催化氢化过程中,通过添加催化量的
钒化合物,可以几乎完全防止
羟胺的积累,这通常会导致<1%
羟胺的浓度。与没有添加
钒化合物的情况相比,所得到的氢化产品更白(更纯),因为几乎不会产生偶氮或偶氮氧化物化合物。氢化,特别是最后阶段的氢化,比没有该添加物的情况下更快进行。因此,获得了在质量恒定和经济方面的实质性优势。