Double-Templating Synthesis of Hierarchical Meso-macroporous Silica Monolith

Hierarchical meso-macroporous materials have attracted much attention due to their potential applications in catalysis,sorption,and separation.The incorporation of interconnected macropores in mesoporous materials is very useful because macropores can favor mass transfer and reduce transport limitations.However,it still remains a challenge to fabricate ordered mesoporous channels in the bicontinuous macroporous framework walls.This paper reports a double-templating route based on a sol-gel method to prepare hierarchical meso-macroporous silica monoliths.The obtained material shows a bicontinuous macroporous structure with highly ordered meso-channels distributing inside the macroporous skeleton walls.The bimodal pore structure was formed under the action of the two templates.The organic polymer was added to induce a phase separation taking place at the solgel transition and thus form the bicontinuous macroporous structure.Meanwhile,a nonionic surfactant was introduced to template the formation of ordered mesostructure inside the macroporous skeleton walls.As characterization by scanning electron microscopy,transmittance electron microscopy,N2 physisorption,and X-ray diffraction,the resulting silica monolith exhibits specific surface area as high as 880 m2/g and pore volume as large as 1.2 cm3/g.The hexagonally ordered mesopores are highly centered at 5.8 nm.Besides,through optimizing the synthesis procedure,the monolith morphology of the resulting materials can be perfectly preserved during the wet gel drying process,and thus a crack-free hierarchical silica monolith with centimeter scale can be obtained.