镍-钒催化剂作用下由苯直接氧化氨化合成苯胺

Direct Oxido-amination of Benzene to Aniline over Nickel-Vanadium Catalysts

设计并制备了Ni鄄V/γ鄄Al2O3催化剂,研究了其上苯用过氧化氢氧化氨化一步直接合成苯胺的性能和不同氨基源对合成苯胺的影响.实验结果显示:在本文条件下,Ni/γ鄄Al2O3和V/γ鄄Al2O3催化剂均能活化苯环上C—H键,使苯一步氧化羟基化为苯酚.Ni、V双组分催化剂则表现出较好的合成苯胺活性和选择性,催化剂中Ni/V摩尔比在5.5时催化活性和选择性最好,目标产物苯胺的选择性达到85%,远远高于主要副产物苯酚的选择性.反应时间宜控制在2h左右,反应最佳温度为333K.尿素在碱性条件下可作为氨基化试剂,在Ni鄄V/γ鄄Al2O3催化剂作用下使苯直接氧化氨化为苯胺,尿素和氨水作为共氨化剂表现出对生成苯胺有利的协同效应.

A series of Ni-V/γ-Al2O3 catalysts were prepared and used in the one-step synthesis of aniline from benzene, hydrogen peroxide, and aqueous ammonia and/or urea. It was found that both Ni-V/γ-Al2O3 and Ni-V/γ-Al2O3 catalysts were effective for the activation of C-H bond of benzene, and the co-existed Ni and V on γ-Al2O3 exhibited synergetic effects which promoted the formation of aniline. When the molar ratio of Ni to V was 5.5, the Ni-V/γ-Al2O3 catalyst showed the highest activity and selectivity for aniline. The highest selectivity to aniline obtained was 85%, which was far higher than that to the by-product phenol. The optimal conditions obtained in present work were as the following： reaction time, 2 h; reaction temperature, about 333 K. Urea was found to be one possible aminating agent for this one-step process in basic reaction media. The synergic effect between ammonia and urea under the conditions investigated was found favorable for the production of aniline.