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Magdalena Król, Justyna Morawska, Włodzimierz Mozgawa and Waldemar Pichór

[1] Breck D.W., Zeolite Molecular Sieves, John Wiley & Sons, New York — London — Sydney — Toronto, 1974. [2] Colella C., Natural zeolites, in: Čejka J., Bekkum H. (Eds.), Zeolites and ordered mesoporous materials: Progress and prospects, Studies in Surface Science and Catalysis 157, Elsevier, 2005, p. 13. http://dx.doi.org/10.1016/S0167-2991(05)80004-7 [3] Gottardi G., Galli E. (Eds.), Natural Zeolites, Mineral and Rocks 18, Springer-Verlag, Berlin Heidelberg, 1985

Open access

Jin Hou and Qiwang Jiang

Abstract

Nanosized NaA zeolite was successfully synthesized by hydrothermal method using tetraethyl orthosilicate (TEOS) and aluminum isopropoxide (AIP) as the main raw materials. The surface modification of NaA zeolite was carried out by silane coupling agent 3-aminopropyltriethoxysilane (KH-550). The effects of silane coupling agent dosage, reaction temperature, reaction time, hydrolysis time and pH value on grafting rate of NaA zeolite were investigated in detail. The zeolites were characterized by XRD, SEM-EDS, FT-IR and TG-DTA. The results showed that the surface of NaA zeolite was modified successfully by KH-550. The optimal modification conditions obtained were as follows: the dosage of coupling agent in 95 % ethanol – 1.6 %, reaction temperature − 70 °C, reaction time – 2 h, hydrolysis time – 20 min, and pH value – 3.5. Under these conditions, the grafting rate of modified NaA zeolite was 3.95 %.

Open access

Shahram Ghanbari and Behzad Vaferi

Abstract

Zeolites are microporous aluminosilicate/silicate crystalline materials with three-dimensional tetrahedral configuration. In this study, the degree of crystallinity of the synthesized Linde Type A (LTA) zeolite, which is the main indicator of its quality/purity is tried to be modeled. Effect of crystallization time, temperature, molar ratio of the synthesis gel on the relative crystallinity of the LTA zeolites is investigated using artificial neural networks. Our experimental observations and some data collected from literature have been used for adjusting the parameters of the proposed model and evaluating its performance. It has been observed that two-layer perceptron network with eight hidden neurons is the most accurate approach for the considered task. The designed model predicts the experimental datasets with a mean square error of 3.99 × 10-6, absolute average relative deviation of 8.69 %, and regression coefficient of 0.9596. The proposed model can decrease the required time and number of experiments to evaluate the extent of crystallinity of the LTA zeolites.

Open access

Karolina Maduna Valkaj, Vesna Tomašić, Andrea Katović and ElżBieta Bielańska

1. Introduction The copper containing MFI zeolites (Cu-MFI) have been proven to be very active in catalytic reduction of NO x by ammonia or hydrocarbons as well as in the direct decomposition of NO to nitrogen and oxygen [ 1 - 16 ]. Unfortunately, in the presence of water vapor or sulphur dioxide in the feed, Cu-MFI catalysts suffer from deactivation under high temperature conditions [ 17 ]. In the literature several different methods of preparation of Cu-MFI catalysts are described. The methods range from classical ion exchange to solid state exchange

Open access

Magdalena Król, Justyna Morawska, Włodzimierz Mozgawa and Waldemar Pichór

[1] Ciciszwili G.W., Andronikaszwili T.G., Kirow G.N., Filizowa Ł.D., Zeolity naturalne (in Polish), WNT, Warszawa, 1990. [2] Breck D.W., Zeolite Molecular Sieves, John Wiley & Sons, New York — London — Sydney — Toronto, 1974. [3] Christidis G.E., Papantoni H., Open Miner. J., 2 (2008), 1. http://dx.doi.org/10.2174/18744567000802010001 [4] Moirou A., Vaxevanidou A., Christidis G., Paspaliaris I., Clay. Clay Miner., 48/5 (2000), 563. http://dx.doi.org/10

Open access

Jinghong Ma, Yuhong Kang, Ning Ma, Wenming Hao, Yan Wang and Ruifeng Li

Abstract

A high-acidity HUSY zeolite with mesoporous structure was prepared by alumination with a dilute aqueous NaAlO2 solution and characterized by XRD, N2 adsorption, IR framework vibration and 29Si MAS NMR methods. The results indicated the extra-framework aluminum was reinserted into the tetrahedral framework through isomorphic substitution of framework Si (0Al) sites by Al ions, whereas the crystal and micropore structure were unaltered. FTIR spectra of hydroxyl vibrations and pyridine adsorbed on realuminated zeolites showed that the number of Brønsted acid sites and strong Lewis acid sites increased whereas weak Lewis acid sites decreased twice. The mesoporous structure composed of inter-and intra-crystalline pores in the aluminated HUSY increased the external surface area of the zeolite, improving accessibility of molecules to the active sites and enhancing its catalytic ability. The realuminated HUSY zeolite supported with Ru catalyst exhibited a higher catalytic activity for benzene hydrogenation than the parent HUSY zeolite; the reaction rate in comparison to the mesozeolite increased by 5.5 times.

Open access

F. Tutti, S. Kamyab, M. Barghi and A. Badiei

Abstract

In the present study, edingtonite has been extracted from natural zeolite clinoptilolite by simulating the natural hydrothermal conditions in the laboratory, under the influence of solutions with different concentrations of Ba+2 and Na+, varying from 0.5 to 2.8 mol/L, at 150 °C. In this work, the essential hydrothermal conditions have been provided by hydrothermal autoclaves. The natural and laboratory prepared samples were characterized by XRD, XRF and SEM methods.

Open access

Meiry G. F. Rodrigues, Antonielly S. Barbosa, Ana C. F. Coriolano, Edjane F. B. Silva and Antonio S. Araujo

References [1] LAWTON S.L., FUNG A.S., KENNEDY G.J., ALEMANY L.B., CHANG C.D., HATZIKOS G.H., LISSY D.N., RUBIN M.K., TIMKEN H.K.C, STEUERNAGEL S., WOESSNER D.E., J. Phys. Chem., 100 (1996), 3788. [2] CORMA A., CORELL C., FORNES V., KOLODZIEJSKI W., PEREZ-PARIENTE J., Zeolites, 15 (1995), 576. [3] DELITALA C., CADONI E., DELPIANO D., MELONI D., MELIS S., FERINO I., Micropor. Mes., 110 (2008), 197. [4] KUMAR G.S., SARAVANAMURUGAN S., HARTMANN M., PALANICHAMY M., MURUGESAN V., J. Mol. Catal. A

Open access

Ashok Borhade and Arun Dholi

.1063/1.1660796 [13] Chang I.F., J. Electrochem. Soc., 121 (1974), 815. http://dx.doi.org/10.1149/1.2401925 [14] Godber J., Ozin G.A., J. Phys. Chem., 92 (1988), 4980. http://dx.doi.org/10.1021/j100328a032 [15] Newsam J.M., IN: A.K. Cheetham, P. Day (Eds.), Solid State Chemistry: Compounds, Chapter 7, Oxford University Press, Oxford, 1992. [16] Meier W.M., Olson D.H., Baerlocher Ch., Atlas of Zeolite Structure Types, Fourth ed., Elsevier, London, 1996. [17] Neurgaonkar R

Open access

A. Borhade and S. Wakchaure

[1] Pauling L., Z. Kristallogr., 74 (1930), 213. [2] Barrer R.M., Cole J.F., J. Chem. Soc. A, (1970), 1516. [3] Veit T., Buhl J.CH., Haffmann W., Cat. Today, 8 (1991), 405. http://dx.doi.org/10.1016/0920-5861(91)87019-J [4] Buhl J.CH., Engelhart G., Felsche L., Zeolites, 9 (1989), 40. http://dx.doi.org/10.1016/0144-2449(89)90007-9 [5] Borhade A.V., Wakchaure S.G., Inter. J. Chem., 2(1) (2010), 3. [6] Van