A catalytic membrane nano reactor (CMNR) with deep-permeation nanocomposite structure (DPNS) has been fabricated by flowing synthesis for methanol dehydrogenation to formaldehyde. In this structure, Cu/ZnO nanoparticles are in situ immobilized in the pores of Ti membrane substrate. The characterization by XRD, TGA, XPS, SEM and TEM indicates that the Cu/ZnO nanoparticles with mean size 82 nm was successfully embedded into the membrane pores, and well distributed along the thickness direction of the membrane. In the methanol dehydrogenation reaction, for one sheet of membrane setting up, the selectivity of formaldehyde 98%, the catalyst turnover frequency (TOF) 183 mmol·h-1·g-1, the pressure drop 2.7 kPa with gas permeating the membrane have been measured, under reaction temperature 360 ℃, the gas flux 8 m3·m-2·h-1 through the membrane.
A flow-through catalytic membrane micro-reactor (CMR) with Cu/ZnO/Al2O3 nanoparticles immobilized in porous membrane pores has been developed for hydrogen production by methanol steam reforming (MSR). The characteristics for CMR demonstrated Cu/ZnO/Al2O3 nanoparticles with almost 200 nm were successfully in situ immobilized in membrane pores. During MSR for hydrogen production in CMR by flow-through mode, hydrogen yield of 500 mmol h-1 g-1 cat. and selectivity of 100% can be achieved under the condition of temperature being 360℃, molar ratio of water to methanol of 8.8 and weight hourly space velocity (WHSV) of 9.28 h-1. Compared with the commercial fixed bed reactor, the hydrogen productivity in CMR is one order of magnitude higher, owing to MSR confined in the space of membrane pore with micro-scale. The methanol conversion rate of over 95% can be expected, if five sheets of CMR with thickness of 5 mm was assembly in series.
A membrane adsorber with hierarchically porous HKUST-1 (HP-HKUST-1) immobilized in membrane pores has been fabricated by flowing synthesis. The XRD characteristics indicated that the structure integrity of the HP-HKUST-1 immobilized in the membrane pores can be kept after template agent removed. Other characteristics presented by XPS, FTIR, SEM, TEM and BET proved the effective immobilization of HP-HKUST-1 in membrane pores. Compared with hydrothermal HKUST-1 powder, the adsorption capacity for Congo red and Methylene blue adsorption can be increased several times by hydrothermal HP-HKUST-1 powder, owing to the mesopores with rich active sites for adsorption. When the solution was flowed through the membrane adsorber, the adsorption rate for these adsorbates increased significantly, owing to the enhanced mass transfer in the confined space of the membrane pores with micro or nano scale. After going through seven adsorption-desorption experiments, the membrane adsorber with HP-HKUST-1 immobilized in membrane pores shows a remarkable repeatability.
A micro membrane adsorber with deep-permeation nano structure (DPNS) has been successfully fabricated by flowing synthesis. The nanoparticles are in situ assembled in membrane pores and immobilized in each membrane pores along the direction of membrane thickness. The nanoparticles with a lower size and thinner size distribution can be achieved owing to the confined space effect of the membrane pores. As a concept-of-proof, the nano ZIF-8 and ZIF-67 are fabricated in porous membrane pores for Methyl orange (MO) and Rhodamine B (RhB) adsorption. The adsorption rate is increased significantly owing to the enhanced contact and mass transfer in the confined space. The adsorption capacity for the RhB is also increased, since the size of the nanoparticles assembled in membrane pores is smaller with more active sites exposed. This micro membrane adsorber with DPNS has good reusability, and can provide a promising prospect for industrial application.