利用微胶囊强化沼气提纯过程的纳微界面效应研究

Preparing biomethane by purification of biogas from low-valued biomass is strategically valuable in terms of energy-saving, emission reduction and resource conservation. The energy density of biogas is low due to its rich in CO2, which substantially limits its industrial application. Because of their various excellent properties in the field of CO2 capture, deep eutectic solvents based ionic liquid is a potential choice to promote the industrialization of biomethane. The major limitation of this strategy, however, is that high viscosity and low absorption rate. The viscosity of deep eutectic solvent can be reduced by addition of water. Unfortunately, this method leads to the decrease of absorption capacity. Microencapsulation of deep eutectic solvent is proposed because the specific area of the liquid can be substantially increased and the absorption rate can be enhanced while absorption capacity remains unchanged. How to obtain microcapsules with uniform size and stable properties is the key problem. Herein, in this project, the shell materials are designed and prepared based on molecular level, while the size and scale of microcapsules are controlled with the help of microfluidics. Based on characterization of the microstructure of microcapsules, the prepared microcapsules are used to purify biogas. With the help of the CO2 absorption ability data obtained by experiments, the mechanism of the enhanced biogas purification process is revealed through the theoretical study of the interface effect. The aim of this project includes: establishes the design basis of shell material, broadens the application scopes of microcapsule and microfluidic technology, provides a useful reference for the development of CO2 capture technology.

利用低劣生物质产沼气进而提纯制备生物甲烷，兼具节能、减排和资源化三重意义。但因沼气中含有大量CO2，导致其能量密度低，工业应用受限。低共熔溶剂型离子液体在CO2的捕集方面有着优异性能，是推进生物甲烷工业化应用的潜在选择，但也存在黏度大而导致吸收速率低的问题。加水虽可降低其黏度，但同时也会造成吸收容量的下降。若能将低共熔溶剂微胶囊化，则有望在不影响CO2吸收容量的同时提升相应吸收速率，其中如何获得粒径均一、性状稳定的微胶囊是关键。本项目拟从分子层面设计、制备壳体材料，并借用微流控的技术手段来实现胶囊粒径及性状的调控，再在对胶囊微结构表征的基础上，将所制得的胶囊应用于沼气的纯化，实测相应的CO2吸收性能，进而解析微胶囊高效吸收CO2的纳微界面效应，最终强化沼气的提纯。项目的实施，将建立微胶囊壳体材料的设计依据，拓展微胶囊和微流控技术的应用领域，为CO2捕集技术的发展提供有益参考。

利用低劣生物质产沼气进而提纯制备生物甲烷，兼具节能、减排和资源化三重意义。但因沼气中含有大量CO2，导致其能量密度低，工业应用受限。低共熔溶剂型离子液体在CO2的捕集方面有着优异性能，是推进生物甲烷工业化应用的潜在选择，但也存在黏度大而导致吸收速率低的问题。加水虽可降低其黏度，但同时也会造成吸收容量的下降。本项目创新地提出将低共熔溶剂微胶囊化，以期在不影响CO2吸收容量的同时提升相应吸收速率。.本项目合成了价格低廉、吸收量大的低共熔溶剂（氯化胆碱和尿素混合），基于此筛选出合适的壳材材料PDMS（聚二甲基硅氧烷），通过自制的微流控装置，调节各相流速包封出不同粒径、壳厚的微胶囊，并探究了不同流速对微胶囊尺寸和结构的影响，同时将所制得的微胶囊应用于沼气的纯化，对制备的微胶囊进行吸收性能和循环性能测试，获得其界面效应。实验结果表明低共熔溶剂微胶囊化能够强化CO2的捕集，与游离低共熔溶剂相比，240、350、500 μm尺寸的微胶囊每单位吸收剂对CO2吸收容量分别提高了11 倍、8 倍、3.7倍，吸收速率分别提高了16倍、10倍和4.6倍。除此之外，发现碳酸酐酶的加入能够协同强化低共熔溶剂捕集CO2，240 μm（壳厚20 μm）含最优酶浓度的微胶囊，在308.15 K下其吸收容量和吸收速率分别是未加酶240 μm微胶囊的7.5倍和16倍。与游离低共熔溶剂相比，包封低共熔溶剂和碳酸酐酶、包封低共熔溶剂微胶囊提纯沼气的选择性分别提高了62倍、8.5倍。因此，通过微胶囊化，实现了吸收容量、吸收速率和吸收选择性的大幅度提升。基于本项目资助，发表文章16篇，申请专利2项，圆满完成了预期目标。.综上所述，本项目建立了微胶囊壳体材料的设计依据，定量了微胶囊的纳微界面效应，拓展了微胶囊和微流控技术的应用领域，为CO2捕集技术的发展提供有益参考，也为微胶囊在化工、医药等行业的应用提供了思路。