Fabrication And Catalytic Performance Of UiO-66-NH₂ Film Capillary Microreactor By Flow Synthesis

Microreactor which has a series of unique features over conventional reactor,can notonly greatly improve the efficiency of reaction,but also provide a green and safe environment.Especially,it shows huge advantages when applied to catalytic reactions.Notably,the catalyst and the form of loading in the microchannel are the key of the fabrication of efficient catalytic microreator.In addition,with the metal organic frameworks(MOFs)rising,the MOFs with active catalytic sites,chemical and thermal stability,are gradually emerging.But,there is only a little researches combining microreator with MOFs nowadays.In this paper,considering the special structure and chemical nature of microchannel with the unique advantages of MOFs,we proposed the methods to fabricate efficient and stable catalytic films in microchannel modified by chemical couping agents in flow condition.The main details are as follows:(1)In this paper,the UiO-66-NH2 film was synthesized on the quartz capillary wall modified by APTES via situ flow method,while UiO-66-NH2 film was not achieved by direct situ flow way.The flow rate,which effecting the form of UiO-66-NH2 film,was first studied in this experiment,and we obtained uniform and continuous film at the flow rate of 0.4m L/h.Moreover,it was also found that the H2 O and acetic acid were all favorable for promoting the form of UiO-66-NH2 film.In addition,we also found that the thickness of UiO-66-NH2 film increased with the synthesis time,which was linear correlation with film thickness in a certain range from 8 to 20 h.Finally,knoevenagel condensation reaction was used as probe reaction to test UiO-66-NH2 catalytic film microreactor,which showed excellent catalytic performance.Under the condition that residence time was 10 min and the molar ratio of BA:ECA:DMSO was 1:1:7,the conversion of ECA was reached 98% at 60 ?.And the microreactor showed outstanding stability in continuous run of 10 h.(2)In this work,we developed a facile method to fabricate the efficient capillary quartz microreactor with UiO-66-NH2 films immobilizing Pd nanocatalysts.UiO-66-NH2 film was pre-achieved by the above method.Afterwards,basing on solution impregnation method,Pd species were easy introduced into the prepared UiO-66-NH2 films,and immediately reduced by sodium borohydride(Na BH4).Pd nanocatalysts were highly dispersed in UiO-66-NH2 film,and the film was still complete.Finally,we employed the prepared microreactor to catalyze the reduction of 4-nitrophenol and obtained very exciting results that Pd nanocatalystsshowed efficient catalytic performance.And the conversion of 4-NP maintained at 100% in a long time run of 100 h under the 4-NP concentration of 2m M and a flow rate of 30?L/min.