Sixing Chen,Yi Liu,Yanwei Sun,Guoliang Xu,Taotao Ji,Xiongfu Zhang,Fei Wang,Yi Liu
Concurrent manipulation of orientation and thickness of MOF membranes has become a reliable approach for improving their separation performances. In terms of oriented seeded growth, oriented deposition of MOF nanosheets during seeding process and sealing all intergranular gaps with no discernible increase in membrane thickness during secondary growth have become indispensable. In this study, we pioneered the fabrication of uniform hexagonal-shaped, 20–40 nm thick MIL-96 nanosheets through solvent composition optimization (V H2O /V FA = 1/2). Subsequently, spin coating was employed for c -oriented deposition of uniform MIL-96 seed layer, during which the addition of PVP in the suspension was found to be critical for obtaining qualified seed layer. Finally, well-intergrown, highly c -oriented ultrathin MIL-96 membrane was prepared upon employing NMF as the solvent during secondary growth. Gas permeation results implied that prepared MIL-96 membrane exhibited superior gas separation performance compared with that of a -& b -oriented counterpart.
Solid-liquid biphasic solvents(SLBS) are considering as promising absorption for CO 2 chemical capture because of their potential energy-saving potential and easily separation of solid products. Nevertheless most of the SLB systems still with some defects, such as premature phase transition and viscous solid products. This work proposed a novel non-aqueous biphasic absorbent with controllable solid–liquid phase transition, composed of piperazine (PZ), 2-amino-2-methyl-1-propanol (AMP), and N-methylformamide (NMF). When NMF is 90 % by volume as solvent and the volume ratio of PZ and AMP is 3:1, the absorbent maintained a homogeneous phase with CO 2 loading below 0.729 mol/mol, which was about 60.6 % of the saturated loading (1.202 mol/mol). As the loading further increased, the solid products generated and the solution separated into solid–liquid two phases. And the solid product into the saturated solution was only 14 % of the total volume while contained about 93.29 % of total loading. The phase-transition mechanism was investigated by using 13 C NMR analysis and molecular simulations. Due to the higher reactivity of PZ with CO 2 compared to AMP, CO 2 initially reacted with PZ to form PZCOO − and PZH + . The enhanced polarity of the final products, PZ(COO − ) 2 and PZ(H + ) 2 , together with a marked increase in ESP difference, promotes the formation of small-volume, CO 2 -rich solids in the later stages of absorption. During this process, intermediate products (PZCOO − and PZH + ) interact with AMPCOO − and AMPH + , allowing early-stage dissolution of products in the solvent and ultimately producing easily separable solids with high CO 2 enrichment. The regeneration heat duty of the novel SLBS was estimated about 0.76 GJ/ton CO 2 , representing just 20.0 % of the industry standard for MEA (3.80 GJ/ton CO 2 ), which indicated extremely energy-saving advantage of the novel solvent.
危险品化学品经营许可证（带存储）