酞菁敏化MIL-53(Al)光催化氧化脱硫性能

Photocatalytic desulfurization properties of phthalocyanine sensitized MIL-53(Al)

摘要:

为改善金属酞菁的团聚现象，提高其光催化活性，选取具有框架柔性和大孔结构的MIL-53(Al)为载体，采用水热法将羧基取代金属酞菁（MTcPc，M=Mn、Fe、Co、Ni、Cu、Zn）负载在MIL-53(Al)表面，制备具有吸附-光催化氧化脱硫性能的MTcPc/MIL-53(Al)复合材料，通过SEM、XRD、FTIR、UV-Vis和XPS等表征其形貌、结构和元素分布，在常温常压、氧气作为氧化剂的条件下，以噻吩/正辛烷为模拟燃油，测试MnTcPc/MIL-53(Al)光催化氧化脱硫性能。结果表明，酞菁分子以有序晶态形式较为均匀的分散在载体MIL-53(Al)上，团聚问题得到明显改善，其平面共轭结构对MIL-53(Al)晶体特定方向生长具有明显的诱导作用，与MTcPc相比，MTcPc/MIL-53(Al)的Q带存在一定程度的红移现象，扩展了光响应范围；MnTcPc/MIL-53(Al)表现出最佳的光催化脱硫性能，催化反应150 min，噻吩转化率100%，经五次循环使用，噻吩转化率降至93.01%。机理研究发现，MIL-53(Al)与具有共轭平面结构的MTcPc之间的π-π堆积作用提高了酞菁的分散性，其呼吸效应促进了噻吩分子和氧分子在MTcPc/MIL-53(Al)表面的强吸附富集作用，有利于活性中间体MIL-53(Al)/MTcPc-1O2的形成，从而提高了氧化脱硫的活性；金属酞菁的共轭结构和中心离子的构型也是影响氧化脱硫效率的重要因素

Abstract:

In order to improve the aggregation phenomenon of metal phthalocyanines and enhance their photocatalytic activity, MIL-53(Al) with flexible frame and large pore structure was selected as the carrier, and carboxyl substituted metal phthalocyanines (MTcPc, M=Mn, Fe, Co, Ni, Cu, Zn) were loaded on the surface of MIL-53(Al) by hydrothermal method. MTcPc/MIL-53(Al) composite material with adsorption-photocatalytic oxidation desulfurization performance was prepared. Its morphology, structure and element distribution were characterized by SEM, XRD, FTIR, UV-Vis and XPS, and thiophene/n-octane was used as simulated fuel at room temperature and pressure with oxygen as oxidant. The desulfurization performance of MnTcPc/MIL-53(Al) photocatalytic oxidation was tested. The results showed that the phthalocyanine molecules were evenly dispersed on the carrier MIL-53(Al) in an ordered crystalline form, and the agglomeration problem was significantly improved. The planar conjugated structure of the phthalocyanine molecules had an obvious induction effect on the growth of MIL-53(Al) crystals in a specific direction. The Q-band of MTcPc/MIL-53(Al) has a certain degree of redshift, which extends the optical response range. MnTcPc/MIL-53(Al) showed the best photocatalytic desulfurization performance. After 150 min of catalytic reaction, the thiophene conversion rate was 100%. After five cycles of use, the thiophene conversion rate decreased to 93.01%.Moreover, the breathing effect of MIL-53(Al) promoted the enrichment of thiophene molecules and molecular oxygen on the catalyst surface, which was conducive to the formation of active intermediate MIL-53(Al)/MTcPc-1O2 to improve the photocatalytic desulfurization properties of thiophene. Mechanistic studies revealed that the conjugation structure and central ion configuration of metal phthalocyanine strongly affected the oxidative desulfurization properties of MIL-53(Al)/MTcPc.