Characterization of Zeolites by XRD, SEM, FTIR Analysis and BET Method and Determination of Surface Acidic Properties of Thermal Treated Zeolites

Öz

The surface characteristics of the zeolites need to be known for their effective use especially, as ion exchanger, catalyst, and adsorbent. In this study, the morphological, mineralogical and surface properties of zeolites were investigated by some instrumental analyses such as X-ray diffraction pattern (XRD), Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) and Brunauer-Emmett-Teller (BET) methods. FTIR spectra proved the presence of silanol and bridged hydroxyls on the zeolite surface. The pore properties including surface area, pore volume, pore size distribution, and average pore diameter of the zeolites were determined by N2 adsorption at 77 K using the BET t-plot and density functional theory (DFT) methods. The pore size distribution showed that the zeolites include both micro and mesopores. The specific surface area of zeolites with different SiO2/Al2O3 ratios decreased as the Si/Al ratio increased. XRD Method was used to examine the crystal structures of zeolites and SEM was used to examine the particle structures. Surface acidity of heat activated zeolites was determined using two different methods. Information about the total amount of acid sites on the zeolites was provided by the n-Butylamine titration method. and FTIR spectra provided information about surface acidity.

Anahtar Kelimeler

• Zeolites
• Instrumental characterization
• DRIFT Spectroscopy
• Bronsted and Lewis acidity
• Si/Al ratio

XRD, SEM, FTIR Analizleri ve BET Yöntemiyle Zeolitlerin Karakterizasyonu ve Isıl İşlem Görmüş Zeolitlerin Yüzey Asidik Özelliklerinin Belirlenmesi

Öz

Zeolitlerin özellikle iyon değiştirici, katalizör ve adsorban olarak etkin kullanımları için yüzey özelliklerinin bilinmesi gerekmektedir. Bu çalışmada zeolitlerin morfolojik, mineralojik ve yüzey özellikleri, X-ışını kırınım deseni (XRD), Taramalı Elektron Mikroskobu (SEM), Fourier Dönüşümlü Kızılötesi Spektroskopisi (FTIR) ve Brunauer-Emmett-Teller (BET) yöntemlerinin birlikte kullanıldığı enstrümantal analiz teknikleriyle incelenmiştir. FTIR spektrumlarından, zeolit yüzeylerinde silanol ve hidroksil köprülerinin varlığı kanıtlanmıştır. Zeolitlerin yüzey alanı, gözenek hacmi, gözenek boyut dağılımı ve ortalama gözenek çapı dâhil gözenek özellikleri, BET t-plot ve yoğunluk fonksiyonel teorisi (DFT) yöntemleri kullanılarak 77 K'de N2 adsorpsiyonu ile belirlenmiştir. Gözenek boyut dağılımı, zeolitlerin hem mikro hem de mezo gözenekler içerdiğini göstermiştir. Farklı SiO2/Al2O3 oranlarına sahip zeolitlerin, Si/Al oranı arttıkça özgül yüzey alanında azalma gözlenmiştir. Isıl aktivasyona uğratılmış zeolitlerin yüzey asitlikleri farklı iki yöntem kullanılarak belirlenmiştir. n-Bütilamin titrasyon yöntemiyle zeolitler üzerindeki asit bölgelerinin toplam miktarı ve FTIR spektrumlarından, yüzey asitlikleri hakkında bilgi sağlanmıştır.

Anahtar Kelimeler

• Zeolitler
• Enstrümantal karakterizasyon
• DRIFT Spektroskopisi
• Bronsted ve Lewis asitliği
• Si/Al oranı

Kaynakça

1. [1] Rogers, B., Adams, J., Pennathur, S. 2013. Nanotechnology: The Whole Story, CRC Press. Boca Raton, 395s.
2. [2] Zecchina, A., Bordiga, S., Groppo, E. 2011. The structure and reactivity of single and multiple sites on heterogeneous and homogeneous catalysts: Analogies, differences, and challenges for characterization methods. ss. 1-27. Zecchina, A., Bordiga, S., Groppo, E., ed. 2011. Selective Nanocatalysts and Nanoscience: Concepts for Heterogeneous and Homogeneous Catalysis, Wiley, 348s.
3. [3] Flanigen, E. M. 2001. Zeolites and molecular sieves: an historical perspective. ss 11-37. Van Bekkum, H., Flanigen, E.M., Jacobs P.A., Jensen, J.C. ed. 2001. Studies in Surface Science and Catalysis, Elsevier Science B.V., Netherlands, 1062s.
4. [4] Kunkeler, P. J., Downing, R. S., Van Bekkum, H. 2001. The use of bulky molecules as probes for investigating the contributions of the external and internal pore-wall activities of zeolite catalysts. ss 987-1001. Van Bekkum, H., Flanigen, E.M., Jacobs, P.A., Jensen, J.C. ed. 2001. Studies in Surface Science and Catalysis. Elsevier Science B.V., Netherlands, 1062s.
5. [5] Maesen, T., Marcus, B. 2001. The zeolite scene: An over-view. ss 1-9. Van Bekkum, H., Flanigen, E.M., Jacobs, P.A., Jensen, J.C. ed. 2001. Studies in Surface Science and Catalysis. Elsevier Science B.V., Netherlands, 1062s.
6. [6] Volkov, D. S., Rogova, O. B., Proskurnin, M. A. 2021. Organic Matter and Mineral Composition of Silicate Soils: FTIR Comparison Study by Photoacoustic, Diffuse Reflectance, and Attenuated Total Reflection Modalities. Agronomy, 11(9),1-30.
7. [7] Helfrecht, B. A., Semino, R., Pireddu, G., Auerbach, S. M., Ceriotti, M. 2019. A new kind of atlas of zeolite building blocks. The Journal of Chemical Physics, 151(15), 154112.
8. [8] Gates, W. P., Komadel, P., Madejová, J., Bujdák, J., Stucki, J. W., Kirkpatrick, R. J. 2000. Electronic and structural properties of reduced-charge montmorillonites. Applied Clay Science, 16(5-6), 257-271.

9. [9] Brunauer, S., Emmett, P. H., Teller, E. 1938. Adsorption of gases in multimolecular layers. Journal of the American chemical society, 60(2), 309-319.
10. [10] Su, L. 2019. Research Progress in Organosilane Modification of Clay Minerals. Conservation and Utilization of Mineral Resources, 39(1), 124-130.
11. [11] Valverde, J. L., Cañizares, P., Sun Kou, M. R., Molina, C. B. 2000. Enhanced thermal stability of Al-pillared smectites modified with Ce and La. Clays and Clay Minerals, 48(4), 424-432.
12. [12] Wang, K., Wang, X., Li, G. 2006. Quantitatively study acid strength distribution on nanoscale ZSM-5, Microporous and Mesoporous Materials, 94, 325-329.
13. [13] Akçay, M. 2004. FT-IR Spectroscopic Investigation of the Adsorption Pyridine on The Raw Sepiolite and Fe-Pillared Sepiolite from Anatolia, Journal of Molecular Structure, 694, 21-26.
14. [14] Önal, M., Sarıkaya, Y. 2007. Preparation and characterization of acid-activated bentonite powders. Powder Technology, 172(1), 14-18.
15. [15] Fan, M., Dai, D., Huang, B. 2012. Fourier transform infrared spectroscopy for natural fibres. Fourier transform-materials analysis, 3, 45-68.
16. [16] Bardestani, R., Patience, G. S., Kaliaguine, S. 2019. Experimental methods in chemical engineering: specific surface area and pore size distribution measurements—BET, BJH, and DFT. The Canadian Journal of Chemical Engineering, 97(11), 2781-2791.
17. [17] Flanigen, E.M., Szymanski, H.A., Khatami, H. 1971. Infrared Structural Studies of Zeolite Frameworks, In: Molecular Sieve Zeolites-I. American Chemical Society, 16, 201-229.
18. [18] Roy, B. N. 1990. Infrared Spectroscopy of Lead and Alkaline‐Earth Aluminosilicate Glasses. Journal of the American Ceramic Society, 73(4), 846-855.
19. [19] Alosious Gonsago, C., Albert, H. M., Umamaheswari, R., Joseph Arul Pragasam, A. 2012. Spectral, optical, and thermal studies of pure and Zn (II)-doped L-histidine hydrochloride monohydrate (LHHC) crystals. Journal of thermal analysis and calorimetry, 110(2), 839-845.
20. [20] Byrappa, K., Kumar, B.S. 2007. Characterization of zeolites by infrared spectroscopy. Asian Journal of Chemistry, 19(6), 4933-4935.
21. [21] Tabassum, N., Rafique, U., Ashraf, M. A. 2018. Novel Method for Doping of Vanadium into Zeolites Synthesized from Industrial Refused Materials and Application for Environmental Remediation. Ekoloji, 27(106), 1519-1532.
22. [22] Ali, M.A., Brisdon, B., Thomas, W.J. 2003. Synthesis, characterization and catalytic activity of ZSM-5 zeolites having variable silicon-to-aluminum ratios. Applied Catalysis A: General, 252(1), 149-162.
23. [23] Shirazi, L., Jamshidi, E., Ghasemi, M.R. 2008. The effect of Si/Al ratio of ZSM‐5 zeolite on its morphology, acidity and crystal size. Crystal Research and Technology: Journal of Experimental and Industrial Crystallography, 43(12), 1300-1306.
24. [24] Çağlar, B., Afşin, B., Çubuk, O., Tabak, A., Erdal, Eren., Porikli, S. 2010. Asit Aktifleştirilmiş Bentonit (Ünye) Numelerindeki Asidik Merkezlerinin Teşhisi. Erzincan University Journal of Science and Technology, 3(1), 73-89.
25. [25] Abdul-Moneim, M., Abdelmoneim, A. A., Geies, A. A., Farghaly, S. O. 2018. Synthesis, Characterization and Application of Cancrinite in Ground Water Treatment From Wadı El-Assiuti Area, Assiut-Egypt. Assiut University of Bulletin Environmental Researches, 21(1), 23-40.
26. [26] Vandegehuchte, B. D., Thybaut, J. W., Detavernier, C., Deduytsche, D., Dendooven, J., Martens, J. A., Marin, G. B. 2014. A Single-Event MicroKinetic assessment of n-alkane hydroconversion on ultrastable Y zeolites after Atomic Layer Deposition of alumina. Journal of Catalysis, 311, 433-446.
27. [27] Van der Bij, H. E., Weckhuysen, B. M. 2015. Phosphorus promotion and poisoning in zeolite-based materials: synthesis, characterisation and catalysis. Chemical Society Reviews, 44(20), 7406-7428.
28. [28] Costa, C., Dzikh, I.P., Lopes, J.M., Lemos, F.,Ribeiro, F.R. 2000. Activity–acidity relationship in zeolite ZSM-5. Application of Brönsted-type equations, Journal of Molecular Catalysis A: Chemical, 154(1-2), 193-201.
29. [29] Dai, Q., Zhu, Q., Lou, Y., Wang, X. 2018. Role of Brønsted acid site during catalytic combustion of methane over PdO/ZSM-5: Dominant or negligible? Journal of Catalysis, 357, 29-40.
30. [30] Kianfar, E., Hajimirzaee, S., Mehr, A. S. 2020. Zeolite-based catalysts for methanol to gasoline process: a review. Microchemical Journal, 156(104822), 1-9.