Catalytic Membrane Reactor of Nano (Ag+ZIF-8)@Poly(tetrafluoroethylene) Built by Deep-Permeation Synthesis Fabrication

Abstract

With the PTFE membrane as the substrate, a novel Ag-based catalytic membrane reactor (CMR) was fabricated by deep-permeation synthesis fabrication (DPSF). In DPSF, ZIF-8 was first assembled inside the membrane pores by permeation flow and the depositing reaction of Zn 2+ , and 2-methylimidazole solutions flow through the membrane synergistically. Then, Ag was reduced inside the pores impregnating ZIF-8 nanoclusters by Ag + and reductant solutions flowing through the membrane similarly. The TEM images of the cross-sectional membrane exhibited the composite nanoparticles of Ag+ZIF-8 with good dispersion and size distribution (10−50 nm). The as-synthesized (Ag+ZIF-8)@PTFE was applied to the catalytic reduction of p-nitroaniline to pphenylenediamine in a continuous flow-through reactor and presented remarkable catalyzing performance. The maximal apparent reaction rate constant is 3−4 orders of magnitude higher than that reported with good stability.

Micromembrane absorber with deep‐permeation nanostructure assembled by flowing synthesis

“…The high surface energy of NPs also promotes the immobilization of NPs on membrane walls and improve the immobilization stability of NPs. The high stability of nanoparticles in the deep‐permeation nanostructure has also been demonstrated in our previous works 17‐19 . In addition, compared with MOF powders, the reuse of the micromembrane adsorber can prevent the centrifugation process, thereby further decreasing the loss of the MOF materials.…”

“…That means a deep‐permeation nanostructure (DPNS) should be realized in the membrane absorber. In‐situ assembly of nanoparticles in membrane pores by flowing synthesis is a feasible method for the expected DPNS 17‐19 . During the flowing synthesis, the flowing of precursor solution in the membrane pores by external forces can overcome the surface tension of the precursor solution, so that the precursor solution can be filled in each membrane pore along the whole thickness direction of the membrane 20‐22 .…”

Porous Membrane Reactors for Liquid-Phase Heterogeneous Catalysis

“…Schematic diagram of the (Ag + ZIF-8)@PTFE membrane structure. [Reprinted with permission from ref . Copyright 2020, American Chemical Society, Washington, DC.…”

Membrane adsorber with hierarchically porous HKUST-1 immobilized in membrane pores by flowing synthesis

“…It can be deduced that the adsorption rate constant can be increased about three times for CR adsorption and five times for MB adsorption, after the HP-HKUST powder is immobilized in membrane pores under the condition of adsorption carried out in the flow-through mode. Enhanced contact and mass transfer are the two contributors for the faster adsorption by membrane adsorber, as described in our previous research [16][17][18][19][20][21][22] . The aggregation of the nano HP-HKUST-1 powder can be prevented beyond the scale of membrane pore size.…”

“…In our previous study, flowing synthesis has been developed to immobilize the MOFs particles in membrane pores [16][17][18][19][20][21][22] . During this process, the precursor solution of the MOFs particles is flowing through the membrane by an external force and the MOFs particles can be fabricated and immobilized in membrane pores simultaneously.…”