Issue 19, 1999

The “silica garden’' as a Brønsted acid catalyst

Abstract

The “silica garden’', an amorphous aluminosilicate produced from a solution of sodium silicate seeded with crystalline aluminium nitrate, has been examined by FTIR, TGA, solid-state NMR and catalytic testing. The silica garden is a Brønsted acid catalyst and we characterize its porosity, acidity and catalytic activity. The as-synthesized (AS) and H+-exchanged (H-AS) samples have BET surface areas of 148 and 161 g-1, respectively, with corresponding pore volumes of 0.36 and 0.31 cm3 g-1 and a broad distribution of pore sizes (30–1000 Å in diameter). The average pore size for AS and H-AS is 116 and 88 Å, respectively. The presence of Brønsted sites in the H+-exchanged samples was confirmed by FTIR of adsorbed pyridine. The population of Brønsted acid sites in the H+-exchanged sample with Si/Al=5.3 is lower than in a commercial amorphous aluminosilicate (ASA) with Si/Al=12 because, as NMR reveals, H-AS has proportionally more non-acid generating 6-coordinate aluminium. Catalytic tests reveal that, despite this, the acid sites in H-AS are stronger than in ASA.

Article information

Article type
Paper

Phys. Chem. Chem. Phys., 1999,1, 4669-4672

The “silica garden’' as a Brønsted acid catalyst

C. Collins, R. Mokaya and J. Klinowski, Phys. Chem. Chem. Phys., 1999, 1, 4669 DOI: 10.1039/A905296H

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements