ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Effect of titanium source on structural properties and acidity of Ti-pillared bentonite

Funda Turgut Basoglu

Chemical Engineering Department, Faculty of Engineering, Gazi University, 06570 Ankara, Turkey

E-mail: tfunda@gazi.edu.tr

Abstract: Ti-pillared bentonites (Ti-PBs) were synthesised using bentonite from the Hançılı region in Turkey. Ti(IV) chloride, Ti(IV) ethoxide and Ti(IV) propoxide were used as the titanium sources; the syntheses were carried out using different H⁺/Ti ratios, bentonite suspension percentages and calcination temperatures. Titanium was found in the form of titanium dioxide for all the sources. The Ti(IV) chloride source afforded a sample with a significantly higher specific BET surface area (by 323 m² g⁻¹), TiO₂ content of 50.5 mass % and a more microporous structure with a micropore volume of 0.112 cm³ g⁻¹; the Ti(IV) propoxide source afforded a more mesoporous structure with a higher total pore volume. The micropore region showed the formation of pores of different sizes, while prominent narrow peaks were obtained in the mesopore region. Ti-PBs, which exhibited only the anatase phase of titanium dioxide, yielded high Bronsted and Lewis acidities. When the rutile phase and the anatase phase occurred together, as a result of the lower TiO₂ content, the Bronsted and Lewis acidities of the Ti-PBs decreased. The use of Ti(IV) chloride and Ti(IV) propoxide sources at H⁺/Ti ratios of 4.0 and a bentonite suspension percentage of 2.0 resulted in samples exhibiting strong Brønsted acidity.

Keywords: Ti-pillared bentonite – titanium(IV) chloride – titanium(IV) ethoxide – titanium(IV) propoxide – pore structure – acidity

Full paper is available at www.springerlink.com.

DOI: 10.1515/chempap-2016-0026

Chemical Papers 70 (7) 933–945 (2016)