Magnetic mixed matrix membranes (MMMs) show great potential for enhancing O 2 /N 2 separation efficiency by leveraging the inherent magnetic property differences between O 2 (paramagnetic) and N 2 (diamagnetic). However, one of the major challenges is the establishment and precise control of magnetic channels between magnetic fillers and polymer matrix. To address this issue, herein, ZIF-8 wrapped Fe 3 O 4 nanoparticles (Fe 3 O 4 @ZIF-8) were synthesized using a step-by-step assembly method, and then integrated into polymer of intrinsic microporosity (PIM-1) matrix to develop MMMs with well-defined magnetic channels for O 2 /N 2 separation. In comparison with Fe 3 O 4 , Fe 3 O 4 @ZIF-8 nanoparticles exhibited significantly enhanced compatibility with the polymer matrix, thereby facilitating uniform dispersion and improving interfacial adhesion. Gas permeation experiments revealed that the magnetic PIM-1/Fe 3 O 4 @ZIF-8 MMMs demonstrated enhanced O 2 /N 2 separation performance due to the combined effects of magnetic responsiveness and the presence of ZIF-8 magnetic channels. Under a magnetic field strength of 56mT, the magnetic MMM with a 4 wt% loading of Fe 3 O 4 @ZIF-8 exhibited optimal O 2 /N 2 separation performance with O 2 permeability of 710 Barrer and O 2 /N 2 selectivity of 3.64. These values represented a significant improvement of 42% and 24%, respectively, compared to pure PIM-1 membrane. Moreover, the simultaneous improvement of permeability and selectivity enabled the achievement of Robeson’s 2008 upper bound for O 2 /N 2 separation, underscoring the great potential of Fe 3 O 4 @ZIF-8 nanoparticles for designing magnetic MMMs with favorable structural attributes and exceptional separation efficiency.
Few studies on the low-temperature combustion behavior of MIPK, being a promising fuel additive , have been conducted. In this work, ignition delay times (IDTs) of MIPK were measured in the temperatures ranging between 780–910 K and pressures of 20 and 25 bar using a rapid compression machine (RCM). Oxy-fuel combustion combined with biofuel could remove CO 2 from the atmosphere. The IDTs of MIPK were measured in the temperatures ranging between 1125–1600 K under the O 2 /CO 2 atmosphere at the pressures of 1 and 10 bar using a shock tube . A low to high-temperature MIPK kinetic model (HUST-MIPK model) was proposed, in which the low-temperature sub-model consists of 19 low-temperature reaction classes and was constructed by analogy-based method, the high-temperature sub-model was adapted from the works of Cheng et al.. The predictions of HUST-MIPK model are in good agreement with the present low-temperature IDTs, high-temperature O 2 /CO 2 atmosphere IDTs, and the literature experimental data. The negative temperature coefficient (NTC) behavior was not observed in the temperature range from 790 to 910 K in the present RCM experiments, but was observed for methyl propyl ketone (MPK) and diethyl ketone (DEK) under similar conditions. The low-temperature chemistry of three pentanone isomers (MIPK, MPK, and DEK) was compared using the flux and sensitivity analysis. The comparison of the experimental high-temperature IDTs between O 2 /CO 2 and O 2 /Ar atmospheres indicates the IDTs of MIPK under O 2 /CO 2 atmosphere are longer than those under O 2 /Ar atmosphere at 1 bar, and the effects of CO 2 are almost independent of the pressure. The physical and chemical effects of CO 2 on the ignition were studied in detail.
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