模拟移动床色谱分离技术提取生物丁醇的建模及优化研究

Currently the SMB technology is attracted lots of attention in the modern separation fields due to its high separation efficiency and continuous operation properties. Modeling and optimization of an SMB unit plays an essential role in obtaining the optimal operating parameters. However, there are a few articles concerning the solubility of the target component in the solvent/desorbent and the multi-objective, multi-parameter global optimization is seldom investigated. Hence, in this work recovery of bio-butanol from the fermentation broth based on SMB technology is selected as a model system. This work focuses on the development of a novel SMB model in which the different solubility of the target compound bio-butanol in solvent (water) and in desorbent (methanol) is taken into account. The molecular simulation as well as the theories about adsorption/desorption thermodynamics and kinetics are applied to investigate the desorption mechanism of butanol on the resin structure. Consequently, the limitation of butanol solubility is introduced in the desorption model to construct the novel SMB unit model. The global optimization is carried out subsequently to optimize the SMB unit for the achievement of the optimal operating conditions for recovery of bio-butanol from the fermentation broth. Several novel multi-level optimization strategies are developed to coordinate the relationship between the objectives and parameters. The optimal operating conditions are obtained and used to validate the simulation results. The results of the study can not only enhance the progression of bio-butanol production, but also extend the application of SMB technology to the solubility-limitation and non-aqueous systems. The developed novel SMB model can be significant to complete the chromatographic model system as well.

模拟移动床技术(SMB)是现代分离科学领域中关注的热点。对SMB系统进行建模，利用模型设计并优化操作条件是该技术的关键。但对于组分在溶剂/洗脱剂中存在溶解度差异的体系研究甚少，对其进行系统建模优化的报道更是寥寥无几。因此，本项目针对溶解度受限条件下SMB系统模型的构建及全局优化策略的设计这两大关键科学问题，以提取生物丁醇为研究体系开展研究。首先针对丁醇在溶剂(水)和洗脱剂(甲醇)中溶解度的不同，以微观分子模拟技术和宏观吸/脱附热/动力学理论探讨丁醇脱附机理，构建SMB系统溶解度受限机理模型；其次设计新型高效的多层次优化方案，对该系统进行多目标多参数的全局优化，确定最佳工艺条件指导实际生产。本研究结果不仅可促进生物丁醇产业化的发展，而且能为SMB技术应用到非水相体系提供参考依据，SMB系统溶解度受限机理模型的构建对进一步完善色谱理论模型系统具有重要意义。

模拟移动床（SMB）技术分离效率高，过程连续，且分离过程不涉及相变化，是一种节能高效的现代分离技术。但因其分离机理复杂，工艺条件众多，导致操作困难。对SMB系统进行建模，利用模型设计并优化操作条件是该技术的关键。因此，本项目以提取生物丁醇为研究体系，根据其工艺特色，为其“量身定做”SMB设备，并建立系统模型，通过模型设计并优化操作条件，极大的节省了人力、物力和财力。研究成果主要包括（1）利用分子模拟技术设计高性能吸附介质，并通过后交联技术合成了多种超高交联介质，其比表面积可达到1600 m2/g以上，对生物燃料丁醇的吸附容量比市售的介质提高了50%，高效介质的制备为后续分离提供了硬件基础；（2）发展了溶剂和洗脱剂不同时的梯度色谱的解吸模型，诠释了吸附质丁醇在吸附剂上的解吸机理。开发了丁醇发酵液中ABE多组分竞争吸附模型及吸附、解吸和再生全过程的色谱分离模型，为后续SMB系统建模提供了基本模型；（3）针对溶剂和洗脱剂不一致的情况，发展了SMB系统新模型，利用多层次多目标多参数的优化策略对SMB系统操作参数进行系统优化，指导实际生产；（4）与此同时，开发了与工艺相配套的SMB装备，并进行了“升级换代”，发展出了第三代“智能型”SMB系统，不仅能对分离结果进行可视化仿真模拟，还能自动根据料液情况的改变调整最优的操作条件，极大地简化了操作的复杂性，为后续工业化的推广奠定了基础。提取液中丁醇的浓度是发酵液中的25 倍，纯度和收率分别达到96.78%和97.80%，产率为43.82 g/(h*kg resin)，比传统蒸馏法提取丁醇能耗降低了20%，废水排放量减少了50%以上，且过程连续，自动化程度高，可实现生物丁醇的产业化发展。