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• Polymeric membrane was used in a membrane reactor for ozonation treatment of DEET. • The membrane reactor equipped with membrane distributor, contactor and separator. • Coating the membrane contactor/distributor with PAC achieved greater DEET conversion. • The additional of ferrihydrite lead to deeper DEET mineralization. • Selective removal of water resulted in efficient treatment of DEET in membrane reactor. The ozone treatment of N,N -diethyl-meta-toluamide (DEET) in water was carried out in a membrane reactor that uses ozone-resistant polymer membranes for ozone distribution, catalytic contactor and water separation. Iron oxide (ferrihydrite) nanoparticles supported on powdered activated carbon (CAT1) were used as catalyst, and were coated on the surface of the membrane contactor/distributor. Ferrihydrites promote ozone dissolution and transformation to reactive hydroxyl radicals, and accelerate the conversion and mineralization of DEET. The powdered activated carbon helped retain the organic pollutants in the reaction zone leading to greater conversion and deeper mineralization. Consistently, the catalytic membrane contactor/distributor displayed the highest DEET conversion and TOC reduction over the entire studied range of ozone dosage and reaction residence time. The selective removal water by the membrane separator had the desired effect of concentrating the organic pollutants resulting in their improved treatment. The compact membrane reactor unit equipped with catalytic membrane contactor/distributor and membrane water separator outperformed a semi-batch ozone reactor with 60% DEET conversion compared to 20%, and 30% TOC reduction versus 5%. [ABSTRACT FROM AUTHOR]

Abstract: A novel membrane reactor was designed for the ozonolysis of refractory organic pollutants in water. The reactor employed a membrane contactor and a membrane separator in a concentric arrangement to affect a uniform ozone distribution along the reactor length, while allowing the simultaneous membrane separation and production of clean water. An alumina capillary membrane contactor and a ZSM-5 zeolite pervaporation membrane were used in this study. Using potassium hydrogen phthalate as model pollutant, the performance of the novel membrane reactor was tested and compared to ozone reaction carried out using the capillary membrane contactor and membrane pervaporation using the ZSM-5 membrane. The novel membrane reactor consistently outperformed both membrane processes. Forty-seven percent higher TOC degradation was observed compared to ozone reaction using a capillary membrane contactor. This enhancement is due to the increase in the organic pollutant concentration in the reaction zone as a result of water withdrawal by membrane pervaporation. As in the case of membrane pervaporation, clean water was produced at the permeate outlet of the novel membrane reactor. Clean water with less than 0.5±0.1ppm was collected from the membrane permeate outlet at a rate of 11–15kg−1 h−1 m−2. [Copyright &y& Elsevier]

Abstract: Two types of membrane reactors, the packed-bed membrane reactor (PBMR) and catalytic membrane reactor (CMR) were successfully miniaturized. Zeolites were incorporated as catalyst for reaction and membrane for separation. The membrane microreactors were tested for Knoevenagel condensation reaction between benzaldehyde and ethyl cyanoacetate to produce ethyl 2-cyano-3-phenylacrylate. Supra-equilibrium conversion and high product purity were obtained from selective removal of water during the reaction. A simple computation model was developed to simulate the reaction in the multichannel membrane microreactor using kinetic data from batch reaction, correlated data from membrane separation and published transport data. The influence of reactor geometry (i.e. channel width and membrane location), membrane separation and catalyst properties were evaluated and the results compared well with experimental data. The information provided by the model suggests several ways of improving the reactor performance. [Copyright &y& Elsevier]

A ZIF-8/NaA composite membrane microreactor was fabricated on multi-channel stainless steel plate. NaA zeolite membrane was first introduced into the microchannel as a modification layer via a secondary growth. Subsequently, a layer of ZIF-8 membrane was grown over the NaA zeolite layer as a catalytic layer by using ZnO-induced synthesis method. Such ZIF-8/NaA composite membrane microreactor was applied in continuous flow Knoevenagel condensation of benzaldehyde and ethyl cyanoacetate. Nearly 100% product yield was achieved in a short residence time under mild conditions. Importantly, no obvious deactivation was observed even after 50 h, indicating its excellent stability. [ABSTRACT FROM AUTHOR]

Abstract: Pd membrane reactor for one-step hydroxylation of benzene to phenol was investigated in an effort to reconcile the contradicting reports in the literature. A systematic study of the membrane, reactor and feed mode was conducted. Reactions carried out on Pd-TS-1 and Pd capillary membranes support Niwa''s postulate of in situ hydrogen peroxide formation, but at the same time indicate that reactive species generated by reactions between permeated hydride ions and activated oxygen also participate in the reaction. The former reaction is important at low benzene feed concentrations and for reactors with small membrane area-to-reactor volume ratios. TS-1 catalyst in Pd-TS-1 membrane can significantly improve the yield and selectivity to phenol. High benzene feed concentrations and faster mass transfer gives the reactive species greater opportunity to react directly with benzene resulting in high benzene conversion but poor selectivity. [Copyright &y& Elsevier]

Abstract: An advanced ozone membrane reactor that uses membranes for ozone distribution, reaction contact and selective water separation was used for ozone treatment of a recalcitrant endocrine disrupting compound in water. Experiments and model calculation were employed to examine the ozonation of phthalate in the new reactor. Experimental results showed that fast ozone mass transfer rate is responsible for membrane reactor''s superb performance compared with a semibatch reactor. Selective water removal further enhanced phthalate conversion and TOC removal by concentrating the pollutants in the reaction zone. Clean water was produced by membrane separation. Mathematical model was used to investigate the effect of membranes, reactor design and reaction operation on pollutant conversion and removal. [Copyright &y& Elsevier]

Abstract: Pd–Sil-1 composite membrane consisting of 5μm Pd membrane anchored by multi-leg protrusions to the 2μm Sil-1 intermediate support layer was prepared from Pd/Sil-1 co-seeds. The membrane displays good permeation flux and is stable for 2.5 weeks of permeation and reaction studies. The Pd–Sil-1 composite membrane was employed for direct hydroxylation of benzene to phenol. Reaction parameters including temperature and H2/O2 molar feed ratio were investigated for their effects on benzene conversion, phenol yield, water generation and hydrogen efficiency. [ABSTRACT FROM AUTHOR]

Abstract: Titanium silicalite-1 (TS-1) and mesoporous TS-1p were incorporated as catalyst for the direct hydroxylation of benzene to phenol in a palladium membrane reactor. The zeolite also served as intermediate support layer and diffusion barrier against contaminants. Pd–TS-1 and Pd–TS-1p were characterized and tested for hydrogen permeation before investigating their performance for the benzene direct hydroxylation reaction. The effects of reactor configuration, reaction conditions and catalysts on conversion, product yield and water production were examined. The phenol yield of Pd–TS-1p was the highest followed by Pd–Sil-1 and Pd–TS-1 with Pd–TS-1p and Pd–TS-1 having phenol selectivity higher than 95%. The optimum reactor configuration and H2/O2 molar feed ratio were identified. [ABSTRACT FROM AUTHOR]

Abstract: Titanium silicalite-1 (TS-1) films were prepared on porous α-Al2O3 tubes using nanosized silicalite-1 (Sil-1) particles as seeds by hydrothermal treatment and a TS-1 catalytic membrane reactors (CMR) was reasonably designed and evaluated by phenol hydroxylation with hydrogen peroxide as oxidant. Some factors on influencing TS-1 film formation and catalytic properties were investigated and the TS-1 films were characterized by scanning electron microscope (SEM), transmission electron micrograph (TEM), X-ray diffractometer (XRD), FTIR, UV–vis and X-ray fluorescence (XRF). It was indicated that TS-1 films prepared from Sil-1 and TS-1 seeds were comparable in structure, morphology and reaction behavior. The crystallization time and times of TS-1 film had a strong effect on its morphology, thickness and orientation. However, the film thickness could be easily controlled by crystallization time and times. The Ti/Si ratio in synthesis solution intensely influenced the content of the titanium atoms incorporated as framework Ti that was correlated well with the activity. The maximum Ti (IV) incorporated corresponds to a Ti/Si ratio of approximately 0.02–0.03. A constant conversion for phenol hydroxylation was obtained with the film thickness of over 7.5μm. It is demonstrated that most of the reaction occurred in a shallow layer near the film due to the mass transfer effects in the TS-1 films. [Copyright &y& Elsevier]