Preparation And Performance Of Magnetic Materials Supported Ionic Liquid Polymer Catalysts

Polymer supported ionic liquids could support high amount of ionic liquid, and showbrilliant consistence with reaction system. Magnetic nanoparticles always display highspecific surface area and could be easily separated from reaction system when externalmagnetic field was applied. Thus, magnetic nanoparticles supported ionic liquid polymer isproposed in virtue of the advantages of ionic liquid polymer and magnetic material. Theinvestigation of magnetic nanoparticle supported ionic liquid polymer could favor theindustrial application of ionic liquid, and also show notable significance for thedevelopment of environment-friendly catalysts.Preparation of magnetic nanoparticles, magnetic nanoparticle supported ionic liquidcatalysts, ionic liquid polymer and magnetic nanoparticle supported ionc liquid polymercatalysts was studied in detail in this work. Knoevenagel condensation reaction betweenethyl cyanoacetate and benzaldehyde and transesterification of triolein with methanol wereused as model reaction for investigating the catalytic performance of the catalysts.Firstly, magnetic silica was prepared via a sol-gel process in a reverse microemulsionand combined with solvent-thermal technique. Magnetic nanoparticle was obtained throughalkali treatment. With the increase of the calcination temperature and the magnet content,the crystallinity and magnetic intensity of the magnetic nanoparticle increase, but theparticle size of the magnetic nanoparticle shows little change. The silica layer on thesurface of the magnetic nanoparticle could be controlled via tunning the reaction time ofalkali treatment and the concentration of alkali solution. The silica layer favors the monodispersion and further modification of the magnetic nanoparticles.Secondly, ionic liquid was grafted on the surface of the magnetic silica and magneticnanoparticles. The results showed that the two kinds of supported ionc liquid catalysts showgood catalytic activity. Ionic liquids are mostly immobilized on the internal surface of themagnetic silica, which results in the mass transfer resistance. Magnetic nanoparticlesupported ionic liquid catalysts could be dispersed uniformly in the reation system andform pseudo-homogeneous raction system.Thirdly, ionic liquid polymesr were prepared by “grafting through” and “gfaftingfrom” methods. The results showed that the quaternization degree of the ionic liquidpolymers is low when prepared via the second method. The ionic liquid polymers prepared by the first method show high density of ionic liquid unit.At last, magnetic nanoparticle supported ionic liquid polymer catalysts were preparedby two methods. The first method was the polymerization of1-vinylimidazole ionic liquidwith vinyl group modified magnetic nanoparticle. The other method was hydrolyzation andcondensation of the siloxane group functionalized ionic liquid polymer on the surface ofthemagnetic nanoparticle. The influence of the preparation method and conditions on thestructure and catalytic performance of the catalysts were studied. The results showed thatthe loading amount of ionic liquid in the magnetic nanoparticle supported ionic liquidpolymer is fast higher than that of supported ionic liquid. The chain of ionic liquid polymersupported on the surface of the magnetic nanoparticle is short but the number of the chain islarge in the catalysts prepared by the first method. However, it is in contrast to the catalystsprepared by the second method. For the Knoevenagel condensation reaction, the two kindscatalysts show good catalytic performance. However, for the transesterification of triolein,the catalytic activity of the catalysts prepared by the first method is poorer than that of thecatalysts prepared by the second method, which is probably due to the large sterichindrance caused by the thick chain of the ionic liquid polymer supported on the surface ofthe magnetic nanoparticle.