Synthesis And Catalytic Application Of Aminopropyl Organic Silicon Polymer Microspheres

Organic silicon polymer microspheres has a aminopropyl propyl siloxane shell, which can used as a solid base catalyst as the aminopropyl group can access the proton. Organic silicon polymer microspheres will have different properties by selecting different kernel sphere.In this paper, we mainly focus on the preparation and modification of two different kernel sphere, while the morphology, structure, BET specific surface area and the content of aminopropyl site were characterized. Then we select the Knoevenagel coupling reaction, as the probe experiments for exploring the acid-base properties of the catalysts.On the one hand, the preparation, modification, and characterization of Fe3O4@NH2: Fe3O4 were synthesized by the solvent thermal method, while we explored the influences of different reagents ratio on the morphology of Fe3O4, then we chose APTES as a single source of silicon, while Fe3O4@NH2 were synthesized by controlling the hydrolytic condensation rate, we explored the effect of different quality of APTES. In the aspect of modified catalytic materials, scanning electron microscopy, transmission electron microscopy (TEM), thermogravimetric analysis (TGA), infrared spectroscopy (IR), powder X-ray diffraction (XRD) were used to characterize the prepared catalysts, and the results show that the Fe3O4@NH2 microsphere is a kind of solid base catalyst with a good morphology and high contents of amino active site. The Fe3O4@NH2 microsphere were used to catalyzed the Knoevenagel coupling reaction of benzaldehyde and malononitrile as probe reaction, ultraviolet-visible spectroscopy (UV Vis) and gas chromatography (GC)were used for monitoring reaction, the effect of the reaction temperature, catalyst concentration, the change of morphology after the reaction and the circulation of the catalytic materials was explored, the experimental results show that the yield reached 97% in 2 hours while chose an optimal reaction condition, in particular, ethanol as solvent,60℃ as reaction temperature,5mol% as catalyst concentration.On the other hand, the preparation, modification, and characterization of SiO2@NH2: firstly, the hard template PS microsphere with uniform particle size distribution were synthesized by the dispersion polymerization method; secondly, the PS@SiO2 were prepared by using sol-gel method, then the hollow SiO2 microsphere were prepared by using the method of solvent extraction hard template to remove the PS microspheres; thirdly, APTES was added for modifying the hollow SiO2 microsphere, while we explored the influences of different reagents ratio on the morphology and contents of amino active sites of SiO2@NH2.In the aspect of modified catalytic materials, scanning electron microscopy, transmission electron microscopy (TEM), N2 physical adsorption stripping tester (BET), infrared spectroscopy (IR) were used to characterize the prepared catalysts, and the results show that the SiO2@NH2 microsphere is a kind of solid base catalyst with a good morphology and high contents of amino active site. The SiO2@NH2 microsphere were used to catalyzed the Knoevenagel coupling reaction of benzaldehyde and malononitrile as probe reaction, ultraviolet-visible spectroscopy (UV Vis) and gas chromatography (GC)were used for monitoring reaction, the effect of the reaction temperature, catalyst concentration, the change of morphology after the reaction and the circulation of the catalytic materials was explored, the experimental results show that the yield reached 95% in 0.5 hours while chose an optimal reaction condition, in particular,80℃ as reaction temperature,5mol% as catalyst concentration.