Surface Acidities of Bentonite, Sepiolite, and Synthetic Silica-Aluminas

Abstract

The surface acidities of Bentonite, Sepiolite, and Silica-Aluminas were determined by Hammett indicators, amine titrations, and of pyridine adsorption-IR spectroscopy. The quantitative estimation of surface acidities of silica-aluminas and their natures as Brønsted and Lewis acid sites were evaluated. Lewis and total surface acidity values of sepiolite were higher than bentonite, 0.53 and 2.22 mmole g-1, respectively. Surface acidity values of sepiolite and bentonite were much lower than Siral compounds. Among the Siral compounds, Siral 30 was found to be more effective in terms of acidity. All samples have both Lewis and Brønsted acid centers in which the Lewis sites predominated. IR spectroscopy with pyridine as a probe molecule was still very useful for the estimation of the surface acidities of the silica-alumina and also aluminosilicate structures such as clays and clay minerals.

Keywords

• surface acidity
• Hammett indicators
• amine titration
• pyridine adsorption
• FTIR spectroscopy

References

1. 1. Tanabe K, Misono M, Ono Y, Hattori H. 2 Determination of Acidic and Basic Properties on Solid Surfaces. In: Studies in Surface Science and Catalysis [Internet]. Elsevier; 1989 [cited 2021 Oct 16]. p. 5–25.
2. 2. Kijeński J, Baiker A. Acidic sites on catalyst surfaces and their determination. Catalysis Today. 1989 Mar;5(1):1–120. .
3. 3. Selli E, Forni L. Comparison between the surface acidity of solid catalysts determined by TPD and FTIR analysis of pre-adsorbed pyridine. Microporous and Mesoporous Materials. 1999 Oct;31(1–2):129–40. .
4. 4. Busca G, Gervasini A. Solid acids, surface acidity and heterogeneous acid catalysis. In: Advances in Catalysis [Internet]. Elsevier; 2020 [cited 2021 Oct 16]. p. 1–90. .
5. 5. Liu D, Yuan P, Liu H, Cai J, Qin Z, Tan D, et al. Influence of heating on the solid acidity of montmorillonite: A combined study by DRIFT and Hammett indicators. Applied Clay Science. 2011 Jun;52(4):358–63. .
6. 6. Topaloğlu Yazıcı D, Bilgiç C. Determining the surface acidic properties of solid catalysts by amine titration using Hammett indicators and FTIR-pyridine adsorption methods: Determining the surface acidic properties of solid catalysts. Surf Interface Anal. 2010 Jun;42(6–7):959–62. .
7. 7. Benesi HA. Acidity of Catalyst Surfaces. II. Amine Titration Using Hammett Indicators. J Phys Chem. 1957 Jul;61(7):970–3. .
8. 8. Hart MP, Brown DR. Surface acidities and catalytic activities of acid-activated clays. Journal of Molecular Catalysis A: Chemical. 2004 Apr;212(1–2):315–21. .

9. 9. Brown DR, Rhodes CN. Brønsted and Lewis acid catalysis with ion- exchanged clays. Catalysis Letters. 1997;45(1/2):35–40. .
10. 10. Breen C, Deane AT, Flynn JJ. The acidity of trivalent cation-exchanged montmorillonite. Temperature-Programmed desorption and infrared studies of pyridine and n -butylamine. Clay miner. 1987 Jun;22(2):169–78. .
11. 11. Jankovic L. Metal cation-exchanged montmorillonite catalyzed protection of aromatic aldehydes with Ac2O. Journal of Catalysis. 2003 Aug 15;218(1):227–33. .
12. 12. Breen C. Thermogravimetric study of the desorption of cyclohexylamine and pyridine from an acid-treated Wyoming bentonite. Clay miner. 1991 Dec;26(4):473–86. .
13. 13. Richardson RL, Benson SW. A Study of the Surface Acidity of Cracking Catalyst. J Phys Chem. 1957 Apr;61(4):405–11. .
14. 14. Basila MR, Kantner TR, Rhee KH. The Nature of the Acidic Sites on a Silica-Alumina. Characterization by Infrared Spectroscopic Studies of Trimethylamine and Pyridine Chemisorption 1. J Phys Chem. 1964 Nov;68(11):3197–207. .
15. 15. Bourne KH, Cannings FR, Pitkethly RC. Structure and properties of acid sites in a mixed-oxide system. I. Synthesis and infrared characterization. J Phys Chem. 1970 May;74(10):2197–205. .
16. 16. Cannings FR. Acidic sites on mordenite: an infrared study of adsorbed pyridine. J Phys Chem. 1968 Dec;72(13):4691–3. .
17. 17. Parry E. An infrared study of pyridine adsorbed on acidic solids. Characterization of surface acidity. Journal of Catalysis. 1963 Oct;2(5):371–9. .
18. 18. Tanabe K. Solid acids and bases: their catalytic properties. Tokyo, New York: Kodansha; Academic Press; 1970. 175 p. ISBN: 978-0-12-683250-1.
19. 19. Liu D, Yuan P, Liu H, Cai J, Tan D, He H, et al. Quantitative characterization of the solid acidity of montmorillonite using combined FTIR and TPD based on the NH3 adsorption system. Applied Clay Science. 2013 Aug;80–81:407–12. .
20. 20. Bilgiç C, Topaloglu Yazıcı D, Vural N. Characterizing the surface acidity of bentonite by various methods: The surface acidity of bentonite. Surf Interface Anal. 2010 Jun;42(6–7):1000–4. .
21. 21. Benaliouche F, Boucheffa Y, Ayrault P, Mignard S, Magnoux P. NH3-TPD and FTIR spectroscopy of pyridine adsorption studies for characterization of Ag- and Cu-exchanged X zeolites. Microporous and Mesoporous Materials. 2008 Apr;111(1–3):80–8. .
22. 22. Hughes TR, White HM. A study of the surface structure of decationized Y zeolite by quantitative infrared spectroscopy. J Phys Chem. 1967 Jun;71(7):2192–201. .
23. 23. Emeis CA. Determination of Integrated Molar Extinction Coefficients for Infrared Absorption Bands of Pyridine Adsorbed on Solid Acid Catalysts. Journal of Catalysis. 1993 Jun;141(2):347–54. .
24. 24. Makarova MA, Karim K, Dwyer J. Limitation in the application of pyridine for quantitative studies of brönsted acidity in relatively aluminous zeolites. Microporous Materials. 1995 Jun;4(2–3):243–6. .
25. 25. Khabtou S, Chevreau T, Lavalley JC. Quantitative infrared study of the distinct acidic hydroxyl groups contained in modified Y zeolites. Microporous Materials. 1994 Sep;3(1–2):133–48. .
26. 26. Datka J. Acidic properties of supported niobium oxide catalysts: An infrared spectroscopy investigation. Journal of Catalysis. 1992 May;135(1):186–99. .
27. 27. Turek AM, Wachs IE, DeCanio E. Acidic properties of alumina-supported metal oxide catalysts: an infrared spectroscopy study. J Phys Chem. 1992 Jun;96(12):5000–7. .
28. 28. Busca G. Catalytic materials based on silica and alumina: Structural features and generation of surface acidity. Progress in Materials Science. 2019 Jul;104:215–49. .
29. 29. Akçay M. FT-IR spectroscopic investigation of the adsorption pyridine on the raw sepiolite and Fe-pillared sepiolite from anatolia. Journal of Molecular Structure. 2004 Jun;694(1–3):21–6. .
30. 30. Akçay M. The surface acidity and characterization of Fe-montmorillonite probed by in situ FT-IR spectroscopy of adsorbed pyridine. Applied Catalysis A: General. 2005 Oct;294(2):156–60. .
31. 31. Madejová J. FTIR techniques in clay mineral studies. Vibrational Spectroscopy. 2003 Jan;31(1):1–10. .
32. 32. Yariv S, Michaelian K. Structure and surface acidity of clay minerals. In: Yariv S, Cross H, editors. Organo-clay complexes and interactions. New York: Marcel Dekker; 2002. p. 1–38. ISBN: 978-0-8247-0586-2.
33. 33. Heller-Kallai L. Clay catalysis in reactions of organic matter. In: Organo-Clay Complexes and Interactions. New York: Marcel Dekker; 2002. p. 567–614. ISBN: 978-0-8247-0586-2.
34. 34. Jystad A, Leblanc H, Caricato M. Surface Acidity Characterization of Metal-Doped Amorphous Silicates via Py-FTIR and 15 N NMR Simulations. J Phys Chem C. 2020 Jul 16;124(28):15231–40. .
35. 35. Saito M, Aihara T, Miura H, Shishido T. Brønsted acid property of alumina-based mixed-oxides-supported tungsten oxide. Catalysis Today. 2021 Sep;375:64–9. .
36. 36. Beutel TW, Willard AM, Lee C, Martinez MS, Dugan R. Probing External Brønsted Acid Sites in Large Pore Zeolites with Infrared Spectroscopy of Adsorbed 2,4,6-Tri-tert-butylpyridine. J Phys Chem C. 2021 Apr 29;125(16):8518–32. .
37. 37. Robinson N, Bräuer P, York APE, D’Agostino C. Nuclear spin relaxation as a probe of zeolite acidity: a combined NMR and TPD investigation of pyridine in HZSM-5. Phys Chem Chem Phys. 2021;23(33):17752–60. .
38. 38. Cengiz S, Çavaş L, Yurdakoç K. Bentonite and sepiolite as supporting media: Immobilization of catalase. Applied Clay Science. 2012 Sep;65–66:114–20. .
39. 39. Yurdakoç M, Akçay M, Tonbul Y, Yurdakoç K. Acidity of silica-alumina catalysts by amine titration using Hammett indicators and FT-IR study of pyridine adsorption. Turk J Chem. 1999;23(3):319–218. .
40. 40. Barzetti T, Selli E, Moscotti D, Forni L. Pyridine and ammonia as probes for FTIR analysis of solid acid catalysts. Faraday Trans. 1996;92(8):1401. .