Preparation And Application Of Core-shell Polyionic Liquid Catalyst

In the early 1990s,scientists developed the concept of"green chemistry",which means designing chemical products and processes that reduce or eliminate harmful substances for sustainable development in the industries in which they are used.Catalysis as a important part of the chemical reaction process,more than 80%of the industrial production process can not be separated from the catalyst,through the design and development of suitable catalysts to reduce energy consumption,pollution,improve efficiency and profitability,to achieve the greening of the reaction process,to achieve the purpose of green catalysis.Poly（ionic liquid）s are a class of polymers with excellent properties of both ionic liquids and polymers generated by the monomer of ionic liquids through their own polymerization or loading polymerization reaction,which have broader development prospects than similar ionic liquids.As a relatively new class of nanomaterials in the field of catalysis,the core-shell structured of poly（ionic liquid）s combines the advantages of non-homogeneous and homogeneous catalysts in a controlled manner,with high activity,good recyclability and easy separation.In this paper,we prepared a series of core-shell structured composite nanospheres of poly（ionic liquid）s as heterogeneous catalysts by functional design and morphology control on the surfaces of silica,Fe₃O₄ and organic polymers,and constructed a stable Pickering emulsion catalytic system to achieve substantial progress in interphase mass transfer,product separation and catalyst recycling in heterogeneous reactions.The paper is presented below:（1）Core-shell structured poly（ionic liquid）s nanoreactors with"inner hydrophobic-outer hydrophilic"properties were prepared by St?ber method and reversible addition-rupture chain transfer（RAFT）polymerization.The introduction of hydrophobic silicone as the inner core,poly（ionic liquid）s as the hydrophilic shell,and the immobilization of Pd nanoparticles in the mesoporous pore channel not only ensured the dispersion of the catalyst in water,but also effectively prevented the leaching of Pd species.And the entropy of styrene adsorption by MIE@Pd/Si NP-CPDB in water was calculated by Clausius-Clapeyron equation,which strongly verified that the prepared catalysts could effectively promote the mass transfer and adsorption of reactants or products under the condition of water as solvent.Furthermore,the prepared nano-reactors exhibited excellent catalytic activity in the aqueous phase hydrogenation reaction,maintaining good catalytic activity and stability even after 7 cycles.（2）Thephoto/magneticdual-responsivecore-shell P[x SPA-y DABCO]@SiO₂@Fe₃O₄ composites were prepared by polymerising basic ionic liquids（F-DABCO）and photoresponsive monomers（SPA）on the surface of the alkene-modified SiO₂@Fe₃O₄ nanoparticles by a layer-by-layer preparation method.Among all the prepared catalysts,P[3SPA-2DABCO]@SiO₂@Fe₃O₄ showed superior catalytic performance,which can stabilize soybean oil-methanol Pickering emulsion for a long time,and catalyze the transesterification reaction between ethanol and soybean oil to obtain biodiesel with high yield under the best experimental conditions.In addition,t the catalyst can be quickly separated from the reaction system by the synergistic action of an external magnet and UV irradiation,and still exhibits excellent catalytic activity after multiple cycles.（3）Smart photoresponsive nanomicrospheres in the sandwich configuration azo-p（St-TMGILs）-OEt were prepared by introducing alkaline ionic liquids（TMG ILs）and a first-of-its-kind photoresponsive monomer（azo-TEPIC）on the surface of polystyrene microspheres via a one-pot soap-free emulsion polymerisation nucleation radical polymerisation,and used to construct Pickering emulsions.Pickering emulsions can be reversibly switched between emulsification and breakage by alternate irradiation with UV and visible light.The Pickering emulsion was used for the transesterification of soybean oil and ethanol to produce biodiesel and was found to give yields above 97%under mild reaction conditions with good cycling stability of the catalyst.