催化学报 ›› 2018, Vol. 39 ›› Issue (7): 1263-1271.DOI: 10.1016/S1872-2067(18)63063-3

• 论文 • 上一篇    下一篇

简便方法合成含铁石墨相氮化碳材料及其催化苯直接羟基化制苯酚

薛冰, 陈晔, 洪颖, 马丁阳, 许杰, 李永昕   

  1. 常州大学石油化工学院, 江苏省绿色催化材料与技术重点实验室, 江苏常州 213164
  • 收稿日期:2018-01-19 修回日期:2018-03-19 出版日期:2018-07-18 发布日期:2018-06-07
  • 通讯作者: 许杰, 李永昕
  • 基金资助:

    国家自然科学基金(21673024);江苏省先进催化与绿色制造协同创新中心创新型人才支持项目(ACGM2016-06-28);省部共建煤炭高效利用与绿色化工国家重点实验室开放课题(2017-K28);江苏高校品牌专业建设工程(PPZY2015B145).

Facile synthesis of Fe-containing graphitic carbon nitride materials and their catalytic application in direct hydroxylation of benzene to phenol

Bing Xue, Ye Chen, Yin Hong, Ding-Yang Ma, Jie Xu, Yong-Xin Li   

  1. Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, School of Petrochemical Engineering, Changzhou University, Changzhou 213164, Jiangsu, China
  • Received:2018-01-19 Revised:2018-03-19 Online:2018-07-18 Published:2018-06-07
  • Contact: 10.1016/S1872-2067(18)63063-3
  • Supported by:

    This work was supported by the National Natural Science Foundation of China (21673024), Advanced Catalysis and Green Manufacturing Collabora-tive Innovation Center (ACGM2016-06-28), Foundation of State Key Laboratory of High-efficiency Utilization of Coal and Green Chemical Engineering (2017-K28), and the Top-notch Academic Programs Project of Jiangsu Higher Education Institutions (PPZY2015B145).

摘要:

苯酚是一种重要的基本有机化工原料.全球近90%的苯酚都是经"三步异丙苯法"工艺合成而得,但是该工艺存在单程苯酚收率低(<5%)、酸污染严重等不足.同时由于联产丙酮,苯酚的产量也受丙酮市场所制约.由苯经氧化或羟基化一步法合成苯酚是催化化学领域中一项极具挑战的课题.由于苯分子较难活化,而苯酚易于深度氧化,因此研发和设计具有高活性和高选择性的催化剂是该课题的研究核心.
因具有诸多特殊的理化性质,石墨相氮化碳(g-C3N4)作为一种新型碳质材料近年来在光催化、热催化、燃料电池和气体吸附等领域展示出广阔的应用前景.g-C3N4的类石墨层基本单元为大π共轭的三均三嗪环,对苯分子具有良好的吸附和活化能力.目前,g-C3N4(尤其是具有高比表面的介孔材料)在苯Friedel-Crafts烷基化和酰基化反应、苯的CO2氧化等反应中均显示了良好的催化活性.尽管如此,由于缺乏合适的氧化活性中心,纯的g-C3N4对苯直接羟基化几乎无催化活性.
本课题组曾将乙酰丙酮氧钒和氧化钒负载至介孔g-C3N4,发现该类催化剂在H2O2参与的苯直接羟基化反应中,苯转化率高达18%,而苯酚选择性大于95%.然而,此类介孔g-C3N4均采用硬模板法合成,制备周期长且需要HF溶液蚀刻氧化硅模板.另外,钒基组分在介孔g-C3N4表面也存在着部分溶脱现象.
本文以FeCl3和二氰二胺为前驱体,通过一步热解法直接合成了含铁的g-C3N4材料(Fe-g-C3N4).采用N2吸附-脱附、XRD、TG、FT-IR、UV-vis、XPS光谱和TEM对材料的理化性质进行表征.结果显示,Fe的原位引入能显著提高g-C3N4的比表面积和孔体积,且使其依然保持石墨相结构.同时,富N的g-C3N4材料能有效地锚定Fe离子,使其均匀地分散在载体表面.作为多相催化剂,Fe-g-C3N4在H2O2环境下对苯羟基化合成苯酚的反应表现出较高的催化活性.当反应温度为60℃,其苯酚收率最高可达17.5%,且回收使用多次催化剂活性表现稳定.与之前报道的含铁和负载氧化钒或乙酰丙酮氧钒的g-C3N4催化剂材料相比,Fe-g-C3N4催化剂制备工艺更加简便.

关键词: 苯, 羟基化, 石墨相氮化碳, 苯酚

Abstract:

Fe-containing graphitic carbon nitride (Fe-g-C3N4) materials were synthesized via one-step pyrolysis of FeCl3 and dicyandiamide. The physicochemical properties of the synthesized Fe-g-C3N4 samples were characterized by N2 adsorption-desorption, X-ray diffraction, thermal gravimetric, Fourier transform infrared, UV-vis diffuse reflectance, X-ray photoelectron spectroscopy, and transmission electron microscopy. The Fe cations were anchored by nitrogen-rich g-C3N4, whereas the graphitic structures of g-C3N4 were retained after the introduction of Fe. As heterogeneous catalysts, Fe-g-C3N4 exhibited good catalytic activity in the direct hydroxylation of benzene to phenol with H2O2, affording a maximum yield of phenol of up to 17.5%. Compared with other Fe-and V-containing g-C3N4 materials, Fe-g-C3N4 features a more convenient preparation procedure and higher catalytic productivity of phenol.

Key words: Benzene, Hydroxylation, Graphitic carbon nitride, Phenol