Molecular Simulation Study of Poly (ether-block-amide) Based Mix Matrix Membranes Incorporating 2D Molybdenum Disulfide Nanosheets for Carbon Dioxide Capture Enhancement

• Main Authors: Cian-Yu Chen, 陳芊宇
• Other Authors: 童國倫
• Format: Others
• Language: en_US
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/cv9hv4

碩士 === 國立臺灣大學 === 化學工程學研究所 === 107 === In recent years, two-dimensional materials have widely been used to replace traditional fillers in mix matrix membranes (MMMs). With high affinity for carbon dioxide (CO2), molybdenum disulfide (MoS2) provides great potential to produce MMMs with high permeability and sufficient selectivity in gas separation application. However, it is still a challenge to estimate the performance of using MoS2 as functional fillers in MMMs due to the complex structure. An aim of our study is to develop a methodology to appropriately simulate MoS2-contained MMMs system and also predict the separation performance. We modified the force field parameters in PCFF, which is built in commercial software Materials Studio 2017 R2, and applied the restraint method for a better description of MoS2 nanosheet structure. In this study, Pebax-1657 was chosen as the polymer matrix and a series of MMMs models with MoS2 loading ranging from 0wt% to 20wt% were constructed. By applying molecular dynamics (MD) and Monte Carlo (MC) simulations, we respectively determined the diffusivity and solubility coefficient of CO2 and N2 within the MMMs. Then, to investigate the influence of MoS2 loading on the performance, the permeability via the solution-diffusion mechanism for each gas as well as the ideal gas selectivity for binary gas mixtures were examined. The results reveal that the addition of MoS2 could significant increase the solubility of CO2 at low loading and the upward trend seems to level off with additional loading to 20wt%. Compared to the results of diffusivity, it was found that the solution step dominates the solution-diffusion process. By increasing the MoS2 loading from 0wt% to 20wt%, the permeability of CO2 significantly increased from 32.05 to 129.64 Barrer without sacrificing the permeability selectivity of CO2/N2. Therefore, our results indicate that, at appropriate MoS2 loading, the incorporation of MoS2 could enhance the CO2 capture performance of Pebax-1657 membrane. Our study provides a method to build representative MoS2-contained MMMs models and predict the performance. The results can help followers to efficiently conduct the experiment and design MMMs of other polymer bases as well.