Functionalized Mesoporous Carbon/Silica Nanocomposites For Carbon-Carbon/Carbon-Oxygen (C-C/C-O) Coupling Reaction

Mesoporous materials have attract much research interest in recent years due to their special advantages in many fields such as catalysis,adsorptions and separation.Particularly,carbon/silica mesoporous sister nanospheres,because of its unique structure features,can act as a matrix functionalized by different organic groups and be applied for heterogeneous catalysis and biomimetic catalysis.In this the sis,based on the systematically and in-depth investigations by the combination of different characterization techniques,such as N₂ adsorption,Temperature Programmed Desorption?NH₃-TPD?,Infrared Spectroscopy?FT-IR?,Thermogravimetry?TG?,Solid State NMR,Scanning Electron Microscope?SEM?,Chemical Element Analysis etc.,the synthesis and catalytic application of functional mesoporous carbon/silica nanoparticles were focused on.The obtained main results are summarized as follows:?1?Using novel surfactant cetyltrimethylammonium bromide?CTAB?as templates,kinds of organic compound?triethanolamine,ammonium hydroxide and N-?2-aminoethyl?-3-aminopropyltrimethoxysilane?as alkali sources,the mesoporous carbon/silica nanospheres with different surface morphologic structures and particle sizes were synthesized by using a one-pot soft-templating method.Carbonization in the N₂ inert atmosphere was followed by etching of the silica in the carbon/silica composite nanospheres,resulting in the formation of dendritic mesoporous carbon nanospheres.By high-temperature calcination in air,these composite nanospheres can be directly transformed to dendritic mesoporous silica nanospheres.The obtained mesoporous carbon/silica nanoparticles will be used as catalyst support for the following research.?2?Amino functionalized mesoporous carbon/silica nanospheres were prepared by a simple post-grafting technique,and Henry reaction was used as the probe reaction for the understanding of the relationships of catalyst structure and performance.Among of catalysts,silica based mesoporous silica nanoparticles?MSNs?functionalized with AAPTMS showed the optimal conversion and selectivity,and the reaction rate strongly depended on the concentration and type of used anionic ammonium salt.Finally,a simple mechanism on the Hofmeister series effects on the reactivity was proposed based the delicate change of micro-environment in the pure silica,carbon and hybrid nanospheres.?3?Novel solid acid catalysts have been prepared from mesoporous carbon/silica nanospheres with tunable mesostructures through a carefully controlled sulfonation procedure.Various techniques have been adopted to characterize throughout their structures,porosity,acidity as well as the information related to the sulfonic acid groups.The sulfonic acid group-functionalized mesoporous nanospheres proved to be efficient heterogeneous catalysts in the reactions glycol with the aldehydes having different molecular structures.The chemical reactivity strongly depends on the morphology,the composition,surface hydrophobicity of nanospheres.These datas further confirmed the importance of the micro-environment of support to improve reaction activity.