高氨基嫁接改性炭凝胶吸附分离密闭空间低浓度CO2的研究

Elevated CO2 levels in confined space can lead to impaired functioning and even death to humans. The adsorption process using solids is regarded as a very promising potential for practical applications due to low regeneration energies, wide applications, long adsorption/desorption cycles, and low corrosion. However, the used adsorbents for low-concentration CO2 from the confined space suffered from vapor, low loading of amine, low degree of diffusion and low thermal stability. Herein, to introduce the heteroatoms into the carbon gels framework where they are of high porosity and surface area was designed to adjust the porosity and surface chemistry of the support, and accordingly PEI can be chemically grafted with the active sites on the surface of carbon gels induced by the heteroatom-doping in high efficiency. Moreover, surfactants were used for designing the 2-D network of PEI. High loading and well dispersion of amine can be achieved. The present work will focus on the investigation of the effects of the introduction of heteroatoms on the porosity and surface chemistry, the reaction efficiencies of chemically grafting with different organic amines, and the mechanisms of CO2 adsorption and regeneration of amine-grafted carbon gels. The proposed results gain further insight into the synthesis of the novel functionalized adsorbents to control CO2 in the chambers which is be of prime importance in the manned space engineering project.

密闭空间内，若产生的CO2不及时清除，会对人的健康造成威胁。吸附法因能耗低、使用周期长、无腐蚀等优点，被认为较有应用前景。针对目前低浓度CO2吸附剂存在不耐水，有机胺负载量低、分散度差、与吸附载体结合力不强等问题，设计在炭凝胶合成过程中掺杂异质金属，对其表面化学性质进行有目的的调控，使之能与聚乙烯亚胺（PEI）进行高效嫁接反应，同时通过引入表面活性剂将PEI分散为相互贯穿的聚合物网络，大幅提高PEI负载量、分散度、结合力和利用率。研究炭凝胶孔道微观结构和表面化学性质的调控规律、探讨有机胺的嫁接反应机理和评价氨基改性掺杂型炭凝胶对CO2与水汽的共吸附性能。研究成果将为新型CO2捕集材料功能化设计提供新思路和新方法，对我国载人航天工程具有重要意义。

密闭空间内，若产生的CO2不及时清除，会对人的健康造成威胁。吸附法因能耗低、使用周期长、无腐蚀等优点，被认为较有应用前景。针对目前低浓度CO2吸附剂存在不耐水，有机胺负载量低、分散度差、与吸附载体结合力不强等问题，本研究利用乙酸锆代替碳酸钠作为催化剂参与炭凝胶的溶胶-凝胶过程，研究发现炭化后的材料大孔较多，孔道结构相对丰富，有利于有机胺分散在孔道中。单纯用乙酸锆代替碳酸钠作为催化剂的炭凝胶材料比表面积和总孔容都很小，且孔径分布集中在100nm以上，大孔较多，微孔较少，因此用锆掺杂后的炭凝胶材料能够负载较多有机胺，达到较高的CO2吸附量。锆掺杂炭凝胶浸渍TEPA后的CO2吸附量比较研究表明，浓度越高，吸附效果越好，但当有机胺浓度过高时，会堵塞孔道结构，反而会降低吸附效果；不同载体材料由于孔结构不同，导致有机胺的分散效果也不同。通过调节R/C比，有效改善炭凝胶载体的孔结构，而当这些载体浸渍PEI后，比表面积和孔容发生变化，这些变化会影响吸附剂对CO2的吸附量。电热脱附相较于相同温度下的热吹扫脱附，脱附速率更快。因此电热脱附除了能使吸附剂快速升温至脱附温度，还能对脱附过程有催化作用，提高脱附效率，大大缩短吸附/脱附的循环操作周期，降低吸附剂再生过程的能耗。研究成果将为新型CO2捕集材料功能化设计提供新思路和新方法，对我国载人航天工程具有重要意义。