Chen Yi, Yuan Huili, Xia Haian, Jiang Wei, Yang Can, Hu Gengshen, Lan Youzhao, Fan Maohong
College of Engineering and College of Chemistry, Zhejiang Normal University, Jinhua 321004, China.
Jiangsu Provincial Key Lab for the Chemistry and Utilization of Agro-forest Biomass, College of Chemical Engineering, Nanjing Forestry University, Nanjing 210037, China.
J Colloid Interface Sci. 2020 Jul 15;572:190-197. doi: 10.1016/j.jcis.2020.03.088. Epub 2020 Mar 24.
The volume expansion effect of amine supported on mesoporous silica during CO adsorption process was found for the first time through well-designed experiments and was further confirmed by theoretical calculations. It was found that the residual pore volume of mesocellular silica foam (MCF) based solid amine sorbent (tetraethylenepentamine (TEPA) supported on MCF) gradually decreased with the increase of CO uptake. Moreover, the surface area, the average diameters of window and cell of MCF show a similar changing trend. This is due to the volume expansion effect of TEPA during CO adsorption process, i.e., the total volume of reaction products of TEPA and CO is larger than that of pure TEPA. The products are very sticky and almost lose the liquidity totally even at 80 °C. The sticky products and the volume expansion effect may increase the mass transfer resistance and are not beneficial to higher CO uptakes especially for solid amine sorbent with higher amine loading due to the decrease of pore size and the residual pore volume. DFT calculations based on simple models also indicate that the total volume of the generated products is much larger than that of unreacted amine, further confirming the volume expansion effect of amine during CO adsorption process. DFT calculations also indicate that the volume is even doubled in the presence of moisture. The volume expansion effect of solid amine sorbent found in this study may help to design the sorbent with high CO capture performance and less the mass transfer resistance.
通过精心设计的实验首次发现了介孔二氧化硅负载胺在CO吸附过程中的体积膨胀效应，并通过理论计算进一步得到证实。研究发现，介孔泡沫二氧化硅（MCF）基固体胺吸附剂（MCF负载四乙烯五胺（TEPA））的残余孔体积随着CO吸附量的增加而逐渐减小。此外，MCF的比表面积、窗口和孔的平均直径呈现出类似的变化趋势。这是由于TEPA在CO吸附过程中的体积膨胀效应，即TEPA与CO反应产物的总体积大于纯TEPA的体积。产物非常粘稠，即使在80℃时也几乎完全失去流动性。粘稠的产物和体积膨胀效应可能会增加传质阻力，不利于更高的CO吸附量，特别是对于胺负载量较高的固体胺吸附剂，因为孔径和残余孔体积会减小。基于简单模型的密度泛函理论（DFT）计算也表明，生成产物的总体积远大于未反应胺的体积，进一步证实了胺在CO吸附过程中的体积膨胀效应。DFT计算还表明，在有水存在的情况下体积甚至会翻倍。本研究中发现的固体胺吸附剂的体积膨胀效应可能有助于设计具有高CO捕获性能且传质阻力较小的吸附剂。
