多区式模拟移动床离子排斥新技术脱除木质纤维素水解液中抑制物的基础应用研究

The sugar and acid in the lignocellulosic hydrolysates can be effectively separated using SMB-IEC technology. However, so far the systematic theoretical models have not been established, which lead to the complexity and high cost for SMB-IEC operation. Moreover, the current SMB-IEC system can only separate sugar-acid two components. These are the bottlenecks for the large-scale application of SMB-IEC technology to detoxify the inhibitors from the hydrolysates. Therefore, the following studies will be carried out in this project: 1) The SMB-IEC separation mechanism will be explored by investigation of the competitive adsorption behaviors of the main components in the hydrolysate with the combination of several theoretical models, for instance, the real adsorption solution theory, Pitzer activity model as well as the ion-exclusion model; 2) The new multi-zone SMB-IEC unit will be designed optimally to realize the multi-component separation, i.e., strong electrolyte (sulfuric acid), weak electrolytes (acetic acid, etc.) and non-electrolytes (sugar and HMF, etc.). Afterwards, the multi-zone SMB-IEC system model will be established, and the operating conditions will be designed and optimized to guide the practical operation, which will enable a sharp reduction of the running costs; 3) Considering the heterogeneous flow distribution in the radial direction of the chromatographic column during the large-scale process, the two-dimensional (2D) IEC chromatographic column model will be established by integration into the Navier-Stokes equation. Meanwhile, the 2D model will be combined with the multi-zone SMB-IEC system model as well to establish a novel 2D multi-zone SMB-IEC system model to predict the multi-component separation process in the large-scale production. This study can provide the fundamental theoretical models as well as a new approach for detoxification of inhibitors from lignocellulosic hydrolysates in the industrial-scale production.

模拟移动床离子排斥色谱技术(SMB-IEC)可有效分离木质纤维素水解液中的糖酸，但因缺乏系统理论模型，导致操作复杂运行成本高，且该技术目前只能分离糖和酸两个组分，是制约其大规模推广应用的瓶颈所在。为此，本项目拟开展如下研究：1）基于真实吸附溶液理论，结合Pitzer活度系数和离子排阻模型，研究水解液中各组分的竞争吸附行为，探讨分离机理；2）通过优化设计，开发多区式SMB-IEC新工艺，实现水解液中强(硫酸)、弱(乙酸)和非电解质(糖和糠醛等)多组分分离，并构建多区式SMB-IEC系统模型，通过模型设计并优化操作参数，降低生产成本；3）考虑色谱柱放大过程中，径向流场分布的不均匀性，运用Navier-Stokes流体方程建立二维IEC柱模型，并与多区式SMB-IEC模型相结合，构建二维多区式SMB-IEC系统放大新模型。本研究可为实现木质纤维素水解液脱毒的工业化放大生产提供理论基础和实现方法。

发展可再生能源是全球可持续能源发展的趋势，也是我国未来能源发展的必由之路。我国木质纤维素资源丰富，以木质纤维素基为主体的纤维素燃料乙醇已被国家能源局列为重点发展的生物能源之一。众所周知，木质纤维素需要经过酸处理后才能使用，而水解液的预处理成本是制约纤维素燃料乙醇大规模生产的瓶颈所在。本项目自主开发了一套膜-色谱分离集成系统，设计开发的纳滤膜脱毒技术成功脱除了水解液中的抑制物，离子排阻模拟移动床色谱技术（IEC-SMB）实现了糖和酸的高效分离。本项目主要研究内容包括：首先，通过纳滤膜渗滤过程考察了pH和硫酸根浓度对木质纤维素水解液中各溶质截留率的影响。结果表明，水解液中的硫酸根离子能促进羧酸和酚类化合物的透过，对单糖和抑制剂的分离有促进作用；其次，通过构建的道南位阻孔质量守恒模型（DSPM-MS）对渗滤过程进行了模拟，设计了平行多目标的优化策略，以抑制剂除去率、总糖回收率最大化和水用量最小化作为多目标函数，以抑制剂移除率和总糖损失率作为约束条件，求得了三个最优操作点，并利用真实水解液验证了优化结果。结果表明，经过纳滤膜渗滤过程后，葡萄糖、木糖等糖的损失率均小于5%，抑制物浓度小于0.01%，且硫酸浓度几乎不被稀释；而后，通过构建的驻波优化设计方法，对多组分IEC-SMB系统和操作参数进行了全局优化，并通过总传质模型对优化结果进行了验证。结果表明，分离得到的糖和硫酸的纯度及收率均能达到98%以上；最后，探讨了膜-色谱分离集成的协同效应，实现了实验室规模的木质纤维素水解液预处理生产线。本项目的研究成果，为木质纤维素水解液预处理的工业化放大生产，提供了结实的理论基础和实现方法。.共发表论文13篇，其中化工三大刊AIChE，CES和IECR，以及色谱分离领域的top期刊SPT和JCA等高档次论文7篇；授权专利7项；项目执行期间，申请人晋升为教授。研究成果达到预期考核指标。