Showing papers by "Lu Bai published in 2021"

Carbon hollow fiber membranes for a molecular sieve with precise-cutoff ultramicropores for superior hydrogen separation.

Abstract: Carbon molecular sieve (CMS) membranes with rigid and uniform pore structures are ideal candidates for high temperature- and pressure-demanded separations, such as hydrogen purification from the steam methane reforming process. Here, we report a facile and scalable method for the fabrication of cellulose-based asymmetric carbon hollow fiber membranes (CHFMs) with ultramicropores of 3–4 A for superior H2 separation. The membrane fabrication process does not require complex pretreatments to avoid pore collapse before the carbonization of cellulose precursors. A H2/CO2 selectivity of 83.9 at 130 °C (H2/N2 selectivity of >800, H2/CH4 selectivity of >5700) demonstrates that the membrane provides a precise cutoff to discriminate between small gas molecules (H2) and larger gas molecules. In addition, the membrane exhibits superior mixed gas separation performances combined with water vapor- and high pressure-resistant stability. The present approach for the fabrication of high-performance CMS membranes derived from cellulose precursors opens a new avenue for H2-related separations. Energy-efficient hydrogen purification technologies are needed for the hydrogen economy. Here the authors report facile and scalable fabrication of asymmetric carbon molecular sieve membranes for the separation of hydrogen and carbon dioxide.

Task-Specific Ionic Liquids Tuning ZIF-67/PIM-1 Mixed Matrix Membranes for Efficient CO2 Separation

Abstract: Ionic liquids (ILs) have become attractive in membranes for CO₂ separation because of the designable structure, high CO₂ affinity, and good compatibility and stability. Modification of metal–organic frameworks with ILs is an effective strategy to improve the gas separation performance of mixed matrix membranes (MMMs). In this work, task-specific ionic liquids (TSILs) were incorporated to prepare TSIL@ZIF-67/PIM-1 MMMs and improve CO₂ separation performance because of the high CO₂ solubility and great compatibility toward ZIF-67 and PIM-1. The TSILs (TMGHIM and TMGHPhO) selectively and reversibly interact with CO₂ and improve the interfacial compatibility between ZIF-67 and PIM-1, leading to higher CO₂/CH₄ and CO₂/N₂ selectivities than that of the ZIF-67/PIM-1 MMM and the directly blended membrane (TSIL/ZIF-67/PIM-1). The 10 wt % TMGHIM@ZIF-67/PIM-1 MMM shows enhanced CO₂/N₂ and CO₂/CH₄ selectivities of 13.7 and 10.5, respectively; meanwhile, the CO₂ permeability reaches 12,848.5 Barrer and is 2.5 times that of the pure PIM-1 membrane. The TSIL@ZIF-67/PIM-1 MMMs also show good stability against physical aging.

Preparation of Core/Shell Electrically Conductive Fibers by Efficient Coating Carbon Nanotubes on Polyester

Abstract: Conducting fibers with improved properties and functionalities are needed for diverse applications. Here we report the fabrication of core/shell conductive Dacron fibers by dip-coating method through originating from multi-walled carbon nanotubes (MWCNTs) coated on polyester fibers. The annealing process was conducted to enhance interaction between the conductive shell and polyester core as well as within the MWCNTs network. The properties of two kinds of MWCNTs dispersions and the electrical properties of conductive fibers were studied, respectively. The results show that both MWCNTs-polyurethane resin (MWCNTs-WPU) dispersion and MWCNTs-acrylic resin (MWCNTs-PAA) dispersion present a typical characteristic of pseudo-plastic fluid and an excellent wetting ability to polyester fibers. The ultimate tensile stress and elongation at break for the MWCNTs-PAA coated fiber are 261 MPa and 25.43%. The ultimate tensile stress and the elongation at break are both increasing with the increasing of MWCNTs contents, due to the strong interface bonding ability between the conductive shell and polyester core and strengthen the MWCNTs network. The electrical resistance of the obtained fibers can be controlled in the range from 732 to 30 Ω/cm by changing MWCNTs content, dipping times and annealing temperature. It was found that it is able to light a LED. All results suggest that the conductive fibers embody a good synergy effect of carbon nanotubes and polymers. Therefore, the fabricated conductive fibers have a widely prospect for being applied in the field of flexible electronics.

Process Simulation and Optimization of Ammonia-Containing Gas Separation and Ammonia Recovery with Ionic Liquids

Abstract: Ionic liquids (ILs) have been experimentally proved to be effective for ammonia-containing gas separation and recovery. A systematic strategy including thermodynamic models, process simulation, mul...