Matrimid-JUC-62 and Matrimid-PCN-250 mixed matrix membranes displaying light-responsive gas separation and beneficial ageing characteristics for CO2/N2 separation

The performance of two generation-3 light-responsive metal-organic framework (MOF), namely JUC-62 and PCN-250, was investigated in a mixed matrix membrane (MMM) form. Both of them were incorporated inside the matrimid as the polymer matrix. Using our custom-designed membrane testing cell, it was observed that the MMMs showed up to 9% difference in CO₂ permeability between its pristine and UV-irradiated condition. This shows that the light-responsive ability of the light-responsive MOFs could still be maintained. Thus, this finding is applicable in designing a smart material. Apart from that, the MMMs also has the potential to be applied for post-combustion carbon capture. At loadings up to 15 wt%, both CO₂ permeability and CO₂/N₂ ideal selectivity could be significantly improved and surpassed the value exhibited by most of the MOF-matrimid MMM. Lastly the long term performance of the MMM was also evaluated and it was observed that both MMM could maintain their performance up to 1 month with only a slight decrease in CO₂ permeability observed for 10 wt% PCN-250-matrimid. This study then opens up the possibility to fabricate a novel anti-aging multifunctional membrane material that is applicable as a smart material and also in post combustion carbon capture applications.

Synthesis of Chainlike ZSM-5 Zeolites: Determination of Synthesis Parameters, Mechanism of Chainlike Morphology Formation, and Their Performance in Selective Adsorption of Xylene Isomers

Chainlike zeolites are advantageous to various applications as a catalyst or an adsorbent with specific selectivity; however, it is often very difficult to get desired morphology due to the complexity of zeolite synthesis process. In this work, appropriate parameters for the synthesis of perfect chainlike ZSM-5 zeolites were well determined, which illustrates that the chain length can be controlled by the composition of synthesis mixture, the amount of residual alcohol in the synthesis system, and the crystallization time. Moreover, the mechanism of chainlike crystal growth was investigated by analyzing the surface species during the synthesis process, with the help of density functional theory (DFT) calculation. The results indicate that the formation of disk crystals with proper dimension and flat surface having abundant hydroxyl groups is crucial to the growth of chainlike ZSM-5 crystals; the condensation of Si-OH groups on the (010) facet is energetically more favorable than that on other facets, leading to the growth of MFI crystals along the b-orientation. Through finely tuning the multifarious synthesis parameters, chainlike ZSM-5 zeolites with controllable length in b-orientation are obtained without using any other extra organic additives except the necessary template agent such as tetrapropylammonium hydroxide (TPAOH). Owing to the increased tortuosity of pore channels in the chainlike ZSM-5, the difference between p-xylene and o/m-xylenes in their adsorption behavior and diffusivity is greatly enhanced. These results help to clarify the formation mechanism of zeolites with chainlike morphology and then bring forward an effective approach to get zeolite materials with specific properties in adsorption and catalysis.