Membrane gas separation offers high energy efficiency,
easy operation,
and reduced environmental impacts for vast hydrocarbon recovery in
the petrochemical industry. However, the recovery of real light hydrocarbon
mixtures (e.g., olefin/nitrogen) remains challenging for lack of high-performance
membranes with sufficient reverse selectivity (large molecules permeate
faster) and permeability. Here, we report the incorporation of fine-tuned,
giant-pore featured MIL-101 nanocrystals into rubbery polymers to
fabricate hybrid membranes, which successfully exploited the giant-pore
channels and large sorption volume of the MIL-101 pore system. The
synthesized MIL-101/poly(dimethylsiloxane) (PDMS) hybrid membranes
demonstrated remarkably simultaneous improvement of gas permeance
and separation factor for the model gas mixture propylene/nitrogen.
Compared with the pristine PDMS, the propylene permeance and separation
factor could be improved by more than 50% by adjusting MIL-101 loading
and operating conditions. By consulting molecular simulations and
gas sorption analysis, we verified that the giant-pore system of MIL-101
and the elastic PDMS chains exhibited a synergistic effect on improving
both hydrocarbon solution and diffusion. Pore properties of MIL-101
contributed favorably to accelerated propylene diffusion in MIL-101
that is 236% faster than that in PDMS. In the meantime, MIL-101 reinforced
the hydrocarbon solution additionally to PDMS, which further facilitated
hydrocarbon transport.
A series of polysiloxane grafted with thermotropic fluorinated mesogens (TSCPFLCP) is designed and synthesized, which effectively improves the processability and toughness of LLDPE.
Zn1-xCoxO (x=0.01, 0.02) dilute magnetic semiconductor thin films deposited on Si (001) substrates at 650℃ by pulsed laser deposition method were studied by X-ray absorption fine structure, X-ray diffraction and magnetic measurement. The typical ferromagnetic hysteresis curves were obtained by superconducting quantum interference device magnetometry at room temperature. The X-ray diffraction results showed that Zn1-xCoxO films were of the wurtzite structure. The X-ray absorption fine structure results revealed that the Co atoms were incorporated into the ZnO lattice and located at the substitutional Zn sites, and a homogeneous phase of Zn1-xCoxO was formed. Comparing the experimental curves with the theoretical calculation results, the additional peak C was assigned to the oxygen vacancies, which indicated that the ferromagnetism of Zn1-xCoxO films was strongly correlated with the existence of oxygen vacancies.
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