Flow Catalysis Performance Based On Metal Organic Frameworks And Metal Phenolic Networks

Flow chemistry is a recent noval technology in which two or more reagents are continuously pumped into one reactor and chemical reaction under control.The advantages of this reactor design for chemical production are in general the potential to work under a continuous operational mode,large surface-to-volume ratios,enhanced heat-and mass transfer,excellent process safety and the ease of increasing throughput by numbering-up.The flow chemistry technology could improve the conversion efficiency,the purity of products,and reduce side reactions,which makes automatic production process more convenient and efficient.The novel functional materials as catalysts contribute to achieve rapid and efficient organic reactions.Among them,heterogeneous catalysts have the advantages of easy recycling and simple product post-treatment technology compared with homogeneous catalysts,and have extensive research value.However,most of heterogeneous catalysts or catalyst carriers are studied in the batch process,which cannot provide enough data support during continuous chemical production procedure.Therefore,it is important to to evaluate the performance of flow chemistry catalysis.Based on the above basis,the research content is as follows:1.Evaluation of flow catalyzed acetalization based on metal organic frameworks MIL-100（Fe）.MIL-100（Fe）was synthesized by hydrothermal method using ferric nitrate and trimesic acid.The structure and properties of MIL-100（Fe）were characterized by X-ray diffraction（XRD）,scanning electron microscope（SEM）,Fourier transform infrared spectroscopy（FT-IR）,etc.,which proved the successful synthesis of the catalyst.Then the MIL-100（Fe）was filled in stainless steel tubes to build a flow catalytic system.The acetalization of benzaldehyde and methanol was used as a template reaction to evaluate the catalytic performance of the catalyst.The result showed that the conversion of benzaldehyde was maintained 91.9%-94.8%at the range of 25-60°C,and the conversion slightly decreased with the increase of flow rate and concentration of reactant.The acetalization of benzaldehyde and methanol can be efficiently catalized in the presence of MIL-100（Fe）,and it is a heterogeneous catalysis procedure.The conversion of benzaldehyde was 94.8%under optimized flow conditions with 4 minutes.After the flow reaction system has been operated continuously for 72 hours,the conversion of benzaldehyde still kept 92.1%.Then,it was proved that the water as by-product can be effectively discharged during the flow reaction process,which avoided the poisoning and deactivation of catalyst.Finally,the general applicability of the acetalization was evaluated.The experimental results showed that the conversion of p-methylbenzaldehyde and p-chlorobenzaldehyde are96.7%and 94.8%,and the conversion rate of p-hydroxybenzaldehyde and p-nitrobenzaldehyde are 36.8%and 9.1%,respectively.When acetalization between alcohols with longer carbon chains and benzaldehyde,the conversion of benzaldehyde becomes lower,and the conversion of ethanol,n-propanol and isopropanol for benzaldehyde are only 20.9%,7.7%and 5.1%,respectively.2.Evaluation of flow catalytic performance of gold-loaded metal phenolic network membrane for 4-nitrophenol reduction.The inner wall of the quartz capillary was chemically treated with sodium hydroxide and hydrochloric acid,and the pretreated capillary was chemically modified with 3-aminotriethoxysilane（APTES）.The tannic acid and Fe³⁺solution were used to dynamically and controllably prepare MPN films during the flow coating process.Experiments showed that the film thickness and the number of coatings has a good linear relationship,and the more the number of coatings,the darker the capillary appearance.The SEM characterization also successfully confirmed the existence of the MPN film on the inner wall of the capillary.The Au nanoparticles produced by the static sealing of chloroauric acid solution,in situ reduction and fixation were prepared a gold-loaded phenolic network membrane on the inner wall of capillary.The incubation time of the chloroauric acid solution can be used to control the particle size and load of Au nanoparticles.A dual-channel syringe pump,capillary,and peek tube was utilized to construct a microchannel flow catalytic device.Finally,the prepared gold-loaded phenolic network membrane was used to catalyze the reduction of 4-nitrophenol（4-NP）.The obtained results indicated that Au nanocatalysts showed highly efficient catalytic performance.The conversion rate of 4-NP maintained100%in a long time run of 80 hours under the 4-NP concentration of 0.1 mmol L^-1 and a flow rate of 80μL h^-1.