基于V-MCM-41介孔材料催化苯直接胺化合成苯胺的研究

Directamination of Benzene to Aniline Over V-MCM-41 Mesoporous Molecular Sieves

目前苯胺的工业生产采用多步反应路线,条件苛刻。本文制备了不同钒负载量的VMCM-41介孔分子筛材料,把他们应用于苯直接胺化合成苯胺的反应,期望在保证较高的苯胺收率下,实现在温和条件下苯胺的一步合成。采用红外、XRD、低温氮气吸附对催化剂样品进行了表征;考察了催化剂在以羟胺为胺化直接胺化合成苯胺的催化活性。实验结果表明:金属钒的添加并未破坏MCM-41介孔分子筛结构,在钒添加适量的情况下,催化剂材料仍具有较高的比表面积和较大的孔容孔径;催化剂的胺化催化活性与钒的负载量直接相关,在苯与羟胺摩尔比为1∶1、苯11.25 mmol、反应温度70℃、催化剂量为0.05 g、介质乙酸7.5 m L(70 vol.%)、反应时间为2 h时,以V-MCM-41(60)为催化剂,苯的最大转化率为68.6%,选择性为98.8%,苯胺收率为67.8%,实现了温和条件下苯胺的一步合成。

The existing methods for aniline production involve multiple reactions,which has harsh conditions.V-MCM-41 catalysts were prepared using different concentrations of VOSO4,then they are used for the direct amination of benzene to aniline,to expect that one step synthesis of aniline with high yield will be achieved under mild conditions. The resulting catalysts were characterized by FT-IR,XRD and nitrogen physisorption measurements. Experimental results showed that vanadium has not destroyed porous structure of MCM-41,and in the case of adding an appropriate amount of vanadium,the material still has a higher specific surface area,high pore volume and pore diameter; the catalytic activities of these catalysts were related to the vanadium content. The highest conversion of benzene was 68. 7% over V-MCM-41（ 60）,with a benzene-to-hydroxylamine ratio of 1∶ 1,benzene 11. 25 mmol,temperature 70℃,catalyst amounts 0. 05 g,acetic acid 7. 5 m L（ 70 vol. %）,and reaction time 2 h. One step synthesis of aniline was achieved under mild conditions.