Alcohol and Water Free Synthesis of Mesoporous Silica Using Deep Eutectic Solvent as a Template and Solvent and Its Application as a Catalyst Support for Formic Acid Dehydrogenation

摘要

Synthetic methods of mesoporous silica using surfactants or ionic liquids as a template have several disadvantages to commercialization such as low economic feasibility and low sustainability. Thus, the development of more ecofriendly and economical synthetic pathways for commercialization of mesoporous silica remains a challenge in the field of mesoporous silica synthesis. In this study, we first report a synthetic method of mesoporous silica (KIE-11) using deep eutectic solvent (DES) of choline chloride/urea as a templating agent and solvent without alcohol and water, except for water needed for hydrolysis of tetraethyl orthosilicate. KIE-11 has high surface area (up to 877 m(2)/g) and pore volume (up to 1.74 cm(3)/g), and its pore size can be easily tailored from 3.3 nm up to 24.5 nm with narrow pore size distribution by only changing the aging conditions. On the basis of various analyses of KIE-11, we deduced pore formation mechanism of mesoporous silica by DES. In addition, we used KIE-11 as a catalyst support for additive-free formic acid dehydrogenation at room-temperature, and KIE-11-supported catalysts showed excellent catalytic activity (TOF: 860.7 mol H-2 mol Pd-1 h(-1)). Comparing to surfactant or ionic liquid-templated methods, the DES-templated synthetic method is much cheaper, more ecofriendly, and more energy efficient. Therefore, this work is expected to open a new avenue for cheap and green synthesis of mesoporous silica on an industrial scale.