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Titolo:
Role of framework on NH4NO3 occlusion in zeolite pores
Autore:
Park, M; Shin, SC; Choi, CL; Lee, DH; Lim, WT; Komarneni, S; Kim, MC; Choi, J; Heo, NH;
Indirizzi:
Kyungpook Natl Univ, Dept Ind Chem, Taegu 702701, South Korea Kyungpook Natl Univ Taegu South Korea 702701 , Taegu 702701, South Korea Kyungpook Natl Univ, Dept Agr Chem, Taegu 702701, South Korea Kyungpook Natl Univ Taegu South Korea 702701 , Taegu 702701, South Korea Pohang Accelerator Lab, Pohang 790784, Kyungbuk, South Korea Pohang Accelerator Lab Pohang Kyungbuk South Korea 790784 uk, South Korea Penn State Univ, Mat Res Lab, University Pk, PA 16802 USA Penn State UnivUniversity Pk PA USA 16802 b, University Pk, PA 16802 USA Penn State Univ, Dept Agron, University Pk, PA 16802 USA Penn State Univ University Pk PA USA 16802 n, University Pk, PA 16802 USA Kyung Il Univ, Coll Gen Educ, Kyungsan 712701, South Korea Kyung Il Univ Kyungsan South Korea 712701 , Kyungsan 712701, South Korea
Titolo Testata:
MICROPOROUS AND MESOPOROUS MATERIALS
fascicolo: 1, volume: 50, anno: 2001,
pagine: 91 - 99
SICI:
1387-1811(200112)50:1<91:ROFONO>2.0.ZU;2-1
Fonte:
ISI
Lingua:
ENG
Soggetto:
MOLTEN-SALT METHOD; NATURAL ZEOLITES; ION-EXCHANGE; DISPERSION; INDIUM;
Keywords:
salt occlusion; zeolite; pore window; size fit; framework charge;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
31
Recensione:
Indirizzi per estratti:
Indirizzo: Park, M Kyungpook Natl Univ, Dept Ind Chem, Taegu 702701, South Korea Kyungpook Natl Univ Taegu South Korea 702701 702701, South Korea
Citazione:
M. Park et al., "Role of framework on NH4NO3 occlusion in zeolite pores", MICROP M M, 50(1), 2001, pp. 91-99

Abstract

Salt occlusion in zeolites is a unique phenomenon and plays an important role in solid and molten state reactions. To elucidate its mechanism, the NH4NO3 occlusion was studied with various zeolites that exhibit diversity in pore shape (channel and cavity), window size, and composition and charge offramework. We also attempted to classify NH4NO3 introduced into zeolite pores by characterizing their properties such as stability against washing with water, thermal behavior, and spectroscopic characteristics. Based on thegeometric consideration between zeolite pores and salts, the salts introduced into zeolite pores could be classified as 'dispersed', 'occluded', and 'trapped' salts. This classification was based on their stability against washing with water. Occluded NH4NO3 salts were present in the pores of zeolites such as AlPO4-18, Na-P1 and 4A, while dispersed ones were observed in those of zeolites such as ZSM-5 and 13X. Framework charge was not essential in salt occlusion, although it affected the occluded amount and stability of occluded NH4NO3. It is clear from these results that the requirement for salt occlusion is the proper size fit between the window size of zeolite pore and the size of each ion pair of salt. Occluded salts were stabilized through geometric fit and/or electrostatic interactions with negatively charged frameworks that led to increase in their stabilities against washing with water and thermal treatment. Therefore, the geometric relationship of zeolite pore to salt plays more crucial role in salt occlusion than framework charge. (C) 2001 Elsevier Science B.V. All rights reserved.

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Documento generato il 07/07/20 alle ore 22:33:22