Functionalized mesoporous SBA-15 silica: Recent trends and catalytic applications

The development of advanced materials for heterogeneous catalytic applications requires fine control over the synthesis and structural parameters of the active site. Mesoporous silica materials have attracted increasing attention to be considered as an important class of nanostructured support materials inheterogeneous catalysis. Their large surface area, well-defined porous architecture and ability to incorporate metal atoms within the mesopores lead them to be a promising support material for designing a variety of different catalysts. In particular, SBA-15 mesoporous silica has its broad applicability in catalysis because of its comparatively thicker walls leading to higher thermal and mechanical stability. In this review article, various strategies to functionalize SBA-15 mesoporous silica have been reviewed with a view to evaluating its efficacy in different catalytic transformation reactions. Special attention has been given to the molecular engineering of the silica surface, within the framework and within the hexagonal mesoporous channels for anchoring metal oxides, single-site species and metal nanoparticles (NPs) serving as catalytically active sites.

10.1039/D0NR00732C

2040-3364

11333-11363

Verma, Priyanka

a826bc8d-272c-4a8b-82ae-2d86affd497f

Kuwahara, Yasutaka

ce81d21e-b744-47ec-b184-ae9fb96be800

Mori, Kohsuke

6c5edbbc-7202-486e-be49-dfd06dd7778e

Raja, Robert

74faf442-38a6-4ac1-84f9-b3c039cb392b

Yamashita, Hiromi

fec03e29-7093-4b3d-bf7f-6a58a152b838

7 June 2020

Verma, Priyanka

a826bc8d-272c-4a8b-82ae-2d86affd497f

Kuwahara, Yasutaka

ce81d21e-b744-47ec-b184-ae9fb96be800

Mori, Kohsuke

6c5edbbc-7202-486e-be49-dfd06dd7778e

Raja, Robert

74faf442-38a6-4ac1-84f9-b3c039cb392b

Yamashita, Hiromi

fec03e29-7093-4b3d-bf7f-6a58a152b838

Verma, Priyanka, Kuwahara, Yasutaka, Mori, Kohsuke, Raja, Robert and Yamashita, Hiromi (2020) Functionalized mesoporous SBA-15 silica: Recent trends and catalytic applications. Nanoscale, 12 (21), 11333-11363. (doi:10.1039/D0NR00732C).

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Accepted/In Press date: 31 March 2020

e-pub ahead of print date: 1 April 2020

Published date: 7 June 2020

Additional Information: Funding Information: Nakagaki’s group has investigated a series of niobia functionalized mesoporous silica (Nb/SBA-15) solid catalysts.188 SBA-15 has been used to stabilize highly dispersed niobium species on the surface to carry out the efficient catalytic reaction. Nb/SBA-15 has been explored in a variety of chemical reactions from various research groups in Knoevenagel condensation, biodiesel production and sucrose hydrolysis.189–191 Despite such interest, these catalysts have never been explored for the esterification reaction. In this report, the authors have explored the esterification of propanoic acid with methanol to study its potential for biodiesel production and further studied the significance of Lewis acidity in the catalytic activity. The N2 physisorption analysis confirmed the surface area of the parent SBA-15 as 750 m2 g−1 and it decreased to 500 m2 g−1 for the highest loading of 32 wt% Nb/SBA-15. The UV-vis spectra showed 2 strong absorption bands at 220 nm and 330 nm attributed to tetrahedral and octahedral Nb oxide species, respectively, coordinated with the silica support material. 2 wt% of Nb/SBA-15 displayed a superior catalytic performance for the esterification reaction at 60 °C. This was supported by the TEM and acidity measurement studies which showed the highly dispersed Nb species possessing a high acid content. Furthermore, the catalyst retains the stability after three runs due to the formation of Si–O–Nb bonds between the Nb precursor and surface silanol groups of the silica support. Funding Information: This work was supported by the International Joint Research Promotion Program of Osaka University. The present work was partially supported by Grants-in-Aid for Scientific Research (No. 19K15311, 26220911, 18K14056, and 19H00838) from the Japan Society for the Promotion of Science (JSPS) and MEXT. YK, KM and HY thank the MEXT program “Element Strategy Initiative” (No. JPMXP0112101003). PV would like to acknowledge the Royal Society-Newton International Fellowship (NIF \R1\180185) for her postdoctoral research funding at the University of Southampton, UK. Publisher Copyright: © 2020 The Royal Society of Chemistry.

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