Hierarchical Catalytic Reactors And Their Hierarchical Catalysis

Catalysis is the cornerstone of the modern chemical industry,and achieving controllable and adjustable catalysis and new concept catalysts has always been the goal of scientific researchers.With controllable and adjustable catalysis and new concept catalysts,chemical reactions can be coordinated in a continuous and multi-step manner,reducing unnecessary separation and purification steps and significantly improving catalytic efficiency.Despite its broad prospects and far-reaching significance,based on existing catalysts and catalytic materials,one cannot directly achieve controllable and adjustable catalytic effects.The reason is that the actual catalysis mechanism is complex and diverse in form,mostly involving complex chemical processes such as tandem / non-tandem,and the use of traditional catalysts and catalytic materials cannot simultaneously control the behavior of the catalytic material itself and effectively the catalytic reaction process separate.In this paper,inspired by biological processes(such as cell partition catalysis,etc.),through the hierarchical control of the catalytic process,a series of temperature-sensitive hierarchical catalytic reactors(ie,catalysts with partial biological functions)were developed.The research can be summarized as follows.This paper first designed a double-layer temperature-sensitive catalytic reactor.The reactor consists of an acidic low-temperature response layer(shape memory layer)with a positive temperature response(that is,a temperature-increasing polymer network swells)and a high-temperature response layer(self-healing polymer with interaction force)loaded with metal nanoparticles.The double-layer construction allows different reactions to be carried out in different areas,achieving catalytic grading(partitioning).At low temperatures,the two temperature-sensitive layer channels are closed,and the substrate cannot react.At modest temperatures,the acidic low-temperature response layer channel is opened,and the substrate can only undergo hydrolysis reactions,that is,non-tandem catalytic reactions.At relatively high temperatures,the two temperature-sensitive layer channels are opened,and the substrate can simultaneously contact the acid sites and the metal nanoparticles,and ahydrolysis reduction reaction occurs,that is,a series of catalytic reactions.By spatially separating the metal nanoparticles and the acid sites,the difference in temperature responsiveness of the dual temperature-sensitive layers is used to realize the non-tandem/tandem-switchable catalysis of the reactor,that is,hierarchical catalysis.Secondly,we designed a three-layer polymer reactor based on the structural design of the dual temperature-sensitive layer and the reactor's staged catalytic capability.Here,we adopted two temperature-sensitive layers with opposite temperature responses,namely a PNIPAm temperature-sensitive layer with negative temperature response and a PAMPS-PVIm temperature-sensitive layer with positive temperature response(PAMPS provides acid sites),and a PAM inert layer covering metal nanoparticles is added between the two temperature-sensitive layers.At low temperature,the interaction between PAMPS and PVIm is not broken,the channel is closed,the substrate can only enter the inert layer through the PNIPAm temperature-sensitive layer,and the metal nanoparticles are in contact with the reduction reaction,that is,non-tandem catalytic reaction.The channel of the acidic low-temperature response layer opens at modest temperatures,and the substrate can only undergo a hydrolysis reaction,that is,a non-tandem catalytic reaction.And at high temperature,the interaction between PAMPS and PVIm is broken,the channel is opened,the substrate first contacts the acidic site for hydrolysis reaction,and the intermediate product then contacts the metal nanoparticles for reduction reaction to complete the series catalytic reaction process.In this way,by using the opposite temperature response of different temperature-sensitive layers,a staged catalysis for non-tandem/tandem-switchable commutation of the substrate is achieved.Finally,in order to achieve the staged catalysis of specific substrates in complex environments,on the basis of summarizing the first two experiments,we designed a double-layer smart polymer reactor by introducing molecular imprinting technology.One layer is a molecularly imprinted layer embedding metal nanoparticles,and the other layer is an acidic temperature-sensitive layer with a positive temperature response.While the reactor has identification capability,it also achieves the stagedcatalysis opposite to the previous two chapters,that is,the cascade / non-cascade commutation catalysis.At low temperature,the substrate channel of the temperature-sensitive layer is opened,the specific substrate contacts the acidic site for hydrolysis reaction,and the intermediate product then contacts the metal nanoparticles through the molecularly imprinted channel for reduction reaction to complete the tandem catalytic reaction.The substrate channel of the temperature-sensitive layer is closed at high temperature,and the specific substrate can only contact the metal nanoparticles through the molecularly imprinted channel to perform a reduction reaction,that is,a non-cascade catalytic reaction.In this way,the characteristics of molecular imprinting are used to realize the tandem / non-tandem commutation of specific substrates,which enriches the types of hierarchical catalytic reactors.Through the above-mentioned research work,we have enriched the hierarchical polymer catalytic reactor,clarified the role of reactor hierarchical catalysis,and made the hierarchical control of the tandem catalytic process possible.