基于可视化技术的乳酸多级孔内传质及反应模型研究

Visualization techniques developed in biological science field have been widely used into materials research, especially into the hierarchy pore catalytic materials. In this project, the mass transfer and reaction model of lactic acid in the hierarchy porous catalysts would be founded based on visualization spectra results, which would direct the design of the hierarchy pore structure and be used to study the multi-scale effect. Firstly, the hierarchy porous structure would be studied through the combination of multi-scale visualization methods, and the parameters of porous structure would be extracted according to the fractal theory. Secondly, the active sites and porous network would be expressed efficiently based on the specific fluorescent dye molecular. Simultaneously，the diffusion and adsorption of lactic acid in the hierarchy pores would be displayed vividly based on in-situ spectral mapping。The information extracted from the photos would be used to found the model of accessible pore and active sites by lactic acid molecular; finally, the diffusion and adsorption model of lactic acid would be calculated according to a series of parameters extracted from photos of IR mapping; finally, the diffusion and adsorption model would be related to pore structure parameters, lactic acid molecular parameters, interphase force, temperature, and so on. The model would be rectified according to the experimental data, which would consummate the diffusion and adsorption model of lactic acid. This project would provide novel thought and theory support for the design of industrial adsorbent and catalysts with ideal performance, in order to perform the corresponding catalytic and separation process with the characteristics such as efficient，energy-saving and eco-friendly.

生命科学领域发展的可视化技术近年来已成为材料科学研究热点方法，特别是多级孔催化材料研究领域。本项目基于可视化光谱技术，建立乳酸分子在多级孔内的传质与反应模型,以此设计合成多级孔催化材料及研究多尺度效应。首先利用多尺度显微手段等对材料孔道结构进行测试，用分形理论研究其多尺度孔结构参数；其次利用设计的分子荧光探针实现材料活性位及孔道网络结构高效表达，以及利用原位光谱成像技术实现乳酸在颗粒内扩散及吸附的直观呈现，在图像处理后实现乳酸可利用的孔道及活性位的模型化分析；最后建立孔结构参数、乳酸分子参数、界面作用力及温度等参数在内的乳酸分子扩散吸附模型，并与宏观测试乳酸吸附扩散数据对照，完善乳酸在多级孔催化材料的扩散与吸附反应模型。该项目为科学设计具有理想传质效应的工业催化剂，实现高效、节能、环保的催化反应及分离过程，应对未来在多孔材料应用领域的重大需求提供新思路和理论依据。

用于液相反应的固体酸催化剂是绿色催化领域以及精细化学品清洁生产工艺的重要研究课题，是目前国内外研究热点。而在液相反应中多相催化剂的孔结构设计，提高活性位利用率以及对相关的催化反应化学认识都是至关重要的。本项目以乳酸催化脱水、催化酯化以及2，3-丁二醇催化转化为目标反应，考察了多级孔NaY分子筛、磺化碳/凹凸棒土固体酸、凹凸棒土稳定磺化聚苯乙烯树脂固体酸催化剂等多种催化剂的合成、结构表征以及催化乳酸脱水以及乳酸酯化反应性能。通过了扫描电子显微镜、透射电子显微镜、N2吸附、压汞法等方法研究了所合成催化剂材料的多级孔结构，并以荧光染料分子为探针，研究了溶液中染料分子在多级孔结构中的传质效应。在此基础上，以乳酸脱水反应和乳酸丁醇酯化反应为探针反应，研究了多级孔固体酸催化剂在液相反应中的催化性能。以水热碳球为模板合成了多级孔NaY分子筛，多级孔结构显著提高了乳酸的转化率，即使在高空速条件下乳酸的选择性仍能保持在90%以上；以葡萄糖为碳源，通过水热碳化过程在凹凸棒土表面沉积了碳物种，磺化后产生的磺化碳固体酸催化剂保留了凹凸棒土堆积孔结构，这种高比表面积以及提高了酸性活性位利用率，显著提高了乳酸传质效率和酯化效率，显示了快速酯化以及稳定的催化剂寿命等特点；用硅烷偶联剂改性凹凸棒土纳米纤维，作为固体颗粒乳化剂，合成了凹凸棒土强化的聚苯乙烯微球，凹凸棒土稳定磺化聚苯乙烯固体酸催化剂显著提高了乳酸酯化效率。同时，研究了2，3-丁二醇在磷改性ZSM-5分子筛、凹凸棒土负载CuO催化剂表面的反应化学，首次揭示了手性多元醇在固体催化剂表面的吸附反应过程，为手性化学品转化的固体催化剂设计提供了有益的参考价值。本项目研究的多级孔催化剂制备方法制备的催化剂已经在有工业应用前景的酯化反应、醚化反应以及过氧化反应中显示出良好的工业化应用前景。