Controllable synthesis and catalytic performance of mesoporous silica nanotube micro-reactor

We present a robust dual-surfactant strategy to reach full control over the size and morphology of multi-channel mesoporous silica nanotubes, using cetyltrimethylammonium bromide (CTAB) and triblock copolymer PEO20PPO70PEO20 (P123) as co-template. The produced mesoporous silica nanotubes were systematically characterized by XRD, N₂ adsorption-desorption, FE-SEM, TEM, UV-vis, ICP and H₂-TPR techniques. The experimental results indicated that the sizes of nanotubes can be controlled from the adjustment of the molar ratio of CTAB and P123 under adequate synthesis conditions. We propose that in this dual-surfactant system, CTAB may function as the template to form mesopore structure, while P123 mainly controls the morphology of materials. In addition, we developed the controllable synthesis of copper-doped multi-channel mesoporous silica nanotube micro-reactor, which was successfully utilized to catalyze the catalytic hydroxylation of benzene with hydrogen peroxide as oxidant. Interestingly, it was found that the catalytic activity can be essentially enhanced by the elongating length of micro-reactors of nanotubes, possibly due to the longer contact time of the reactant and the active sites inside. Our controllable synthesis of mesoporous silica nanotube provides a novel approach to rationalize the design of catalysts as well as their catalytic performance.