核-壳型TiO2@CuO/C微球催化反应/吸附分离耦合体系的构建及脱硫性能研究

In recent years, the problem of environmental pollution of thiophene sulfides from liquid fuel has received considerable attention. Adsorptive desulfurization (ADS) could remove the thiophene sulfides with ultra-deep desulfurization of diesel oil. However, the low adsorptive selectivity and the low adsorptive capacity for organo-sulfur compounds would limit the application of ADS. In this work, TiO2@CuO/C microsphere with core-shell architecture will be synthesized. The TiO2 shell could remove thiophene sulfides from fuel with UV photocatalysis-assisted oxidative desulfurization, and the Cu based-Metal organic frameworks (MOFs) derived porous CuO/C core could adsorb and separate the oxidized products (sulfoxides and/or sulphones). Thus, this microsphere would possess the reaction/adsorption coupling system. First of all, the TiO2@CuO/C is synthesized. The effects of reaction condition on the forming of core-shell architecture are studied and the structural control of morphology, dimension and pore structure of this composite microsphere are discussed. Secondly, formation mechanism of core-shell architecture is studied by characterization, such as scanning electron microscope (SEM), Brunauer-Emmett-Teller surface area measurement (BET), X-ray Diffraction (XRD). Then thiophene sulfides is used as model oil in this work, and the desulfurization efficiency, adsorption capacity, adsorptive selectivity, and life of TiO2@Cu-BTC composite microsphere are determined. Finally, desulfurization thermodynamics and kinetics is studied, and the desulfurization mechanism of reaction/adsorption intergration is elucidated at a molecular level. In short, TiO2@CuO/C microsphere prepared in this work having core-shell architecture will possess excellent adsorption performance and stability, and it will be of guiding significance to the materials applied in ultra-deep desulfurization of diesel.

液体燃料中含硫化合物所带来的环境污染问题备受关注，吸附脱硫技术能够超深度去除柴油中的噻吩类硫化物，但存在吸附容量低和吸附选择性差等问题。本项目拟设计合成一种核-壳结构的TiO2@CuO/C微球，其以TiO2为壳，以铜基MOFs衍生的多孔CuO/C为核，“壳”对噻吩类硫化物进行光催化脱硫反应，“核”对产物亚砜/砜类进行吸附分离，从而构建催化反应和吸附分离的耦合体系。本项目通过合成TiO2@CuO/C微球，研究反应条件对核-壳结构的影响；探索核-壳结构形态、尺寸和孔结构的调控规律，借助多种表征手段来研究核-壳结构的形成机制；以噻吩硫为模型油，研究该核-壳微球的脱硫率、吸附容量、吸附选择性、使用寿命和再生性能等；结合脱硫热力学和脱硫动力学研究，从分子层面阐释其一步实现反应/吸附的耦合脱硫机理。本项目拟构建的核-壳型微球将具有优异的吸附性能和稳定性，这对柴油脱硫材料的应用具有重要的指导意义。

液体燃料中含硫化合物所带来的环境污染问题备受关注，吸附脱硫技术能够超深度去除柴油中的噻吩类硫化物，但存在吸附容量低和吸附选择性差等问题。本项目设计合成了一种核-壳结构的TiO2@Cu-BTC微球，其以TiO2为壳，以铜基MOFs——Cu-BTC为核，“壳”对噻吩类硫化物进行光催化氧化反应，“核”对反应产物亚砜/砜类进行吸附分离，从而构建催化反应和吸附分离的耦合体系。.本项目通过合成TiO2@Cu-BTC微球，研究了反应条件对核-壳结构的影响，探索了核-壳结构形态、尺寸和孔结构的调控规律，借助多种表征手段来研究核-壳结构的形成机制；结果发现，对于制备均一的核壳结构TiO2@Cu-BTC微球，氨水在控制反应速率方面起到非常重要的作用，可以通过调节氨水的加入量来调控Cu-BTC表面的TiO2形态和数量，即调节壳层的厚度；此外，TiO2的加入，促进了Cu2+的还原和Ti2+的氧化，Ti/O和Cu之间发生了电子转移，产生了显著的相互作用。本项目以苯并噻吩（BT）和二苯并噻吩（DBT）为模型油，当反应20min后，BT脱硫率达86%，DBT脱硫率达96%，脱硫量分别达到59.39mg/g和63.76mg/g，模型油中BT和DBT的硫含量也分别降至140和47ppmw；相比Cu-BTC的吸附脱硫，TiO2@Cu-BTC的吸附-催化耦合脱硫效率分别提高了4.6和6.5倍。这说明在脱硫过程中，紫外光辐射促进了BT和DBT的氧化反应，结果噻吩硫被TiO2壳层催化氧化变成了相应的砜类化合物，同时，由于极性差异，这些氧化产物被Cu-BTC核牢牢吸附，而实现了原料和产物的同步分离，减少了后续分离产物的操作；由于TiO2和Cu-BTC的协同作用，使TiO2@Cu-BTC微球具有较高的脱硫效率，能够在短时间内实现快速、深度脱硫。.本项目构建的TiO2@Cu-BTC核-壳型微球具有优异的脱硫性能和稳定性，这对柴油脱硫材料的应用具有重要的指导意义。