Thermal behavior of synthetic faujasite

Ambs, William J.; Flank, William H.

doi:10.1016/0021-9517(69)90416-3

Cited by 23 publications

(4 citation statements)

References 10 publications

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“…These observations agree with an earlier report [16]. Exothermic peaks (900-990 ~ and temperature of mullatization in the range 1030-1065 ~ are attributed to structural transformation, as confirmed by the X-ray analysis [17].…”

Section: Resultssupporting

confidence: 93%

Thermal behaviour of modified faujasites

Chandwadkar

Kulkarni

1980

Journal of Thermal Analysis

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A derivatograph was used to follow the modification of the skeleton structure and thermal stability of zeolites in sodium and ammonium forms. Analogous investigations were carried out by independent methods such as IR and X-ray. Comparison showed good agreement between the results. The controlled dealumination of the Y-type zeolite enhanced the thermal stability.Modified zeolites prepared by treatment with ethylene diamine tetraacetic acid (H4 EDTA) and subsequent activation profoundly alter their structures. Samples treated in this manner show differences in both catalytic activity and adsorptional properties, depending on the SiO~/A120 3 ratio. In particular, the crystallinity of the Y-type zeolite is maintained up to the elimination of roughly one-half of the aluminium [1 ], and then it begins to fall off while the catalytic activity incracking reactions rises [2]. The zeolite-based catalysts containing protons and polyvalent cations are more active [3] as compared to alkali metal zeolites.As regards the cation-deficient zeolites, the thermal behaviour of Y-type zeolites exchanged with ammonium ions has been reported [4,5] to some extent. The effects of the variation of the silica-alumina ratio and the bed geometry on the dehydroxylation and thermal stability of the products have been studied [4] and related [5] to the residual Na § ions in the Y-type zeolite. Kerr [4,6] proposed that ultrastabilization involved the removal of framework aluminum, which is held as AI(OH)~-, AI(OH) 2 § or A13 § ions. The present study was undertaken to obtain additional evidence on the thermal stability of dealuminated zeolites by thermal, X-ray and IR. ExperimentalBinder-free Y-type zeolites in the sodium (SK-40) and ammonium (SK-41) forms were obtained from Union Carbide (USA), dried at 120 ~ and kept for about a week over a saturated solution of ammonium chloride at room temperature. The chemical compositions of the dehydrated zeolites, determined by gravimetric analysis, were as follows:* NCL Communication No.

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Section: Resultssupporting

confidence: 93%

Thermal behaviour of modified faujasites

Chandwadkar

Kulkarni

1980

Journal of Thermal Analysis

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“…Ambs and Flank [16] explained the thermal stability of DAY over 1273 K as a result of the removal of sodium ions which destabilize the framework due to their mineralizing effect. Peri [17] gave preference to the formation of novel Si-O-Si bonds as a result of dehydroxylation of intermediately formed hydroxyl nests.…”

Section: Introductionmentioning

confidence: 99%

Zeolite Y: Synthesis, Modification, and Properties—A Case Revisited

Lutz

2014

Advances in Materials Science and Engineering

134

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Y zeolites dealuminated by steaming were introduced as fluid-cracking catalysts in the year 1970. Extensive research has been done to develop suitable dealumination techniques, to investigate crystal structure, and to characterize catalytic behaviour. However, the origin of the secondary pore system formed in the zeolite structure during dealumination process remained completely obscure over a period of four decades. Open questions concerned also the existence of extraframework siliceous admixture in addition to extraframework aluminium species which can dramatically change the catalytic properties of these zeolites. This paper gives a review on the synthesis of DAY materials and provides some answers to several open questions.

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“…At present, opinion seems to converge on the compromise that both the so-called Bronsted Downloaded by UNIV OF NEW ORLEANS on December 9, 2014 | http://pubs.acs.org Publication Date: August 1, 1974 | doi: 10.1021/ba-1971-0101.ch001and Lewis acid sites are required, with optimum activity coinciding with equal numbers of each(68, 69). Infrared and thermal analytical studies have contributed greatly to an understanding of these materials(3,25,80). The diverse activities shown by zeolite catalysts in many different organic reactions is reviewed by Venuto.…”

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confidence: 99%

Recent Advances in Zeolite Science

Breck¹

1974

Molecular Sieve Zeolites-I

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Zeolite properties are being studied by nearly every type of modern scientific discipline, and they are being utilized in many new chemical engineering processes. Important ad vances include detailed basic information on cations in zeo lites, more understanding of the mechanism of zeolite formation, the formation and character of structural defects and hydroxyl groups, the role of zeolite structure in adsorp tion and catalysis, and the increasing technology of the use of molecular sieve zeolites in catalysis and adsorption. 'Tihe discovery of synthetic crystalline zeolites has resulted in wide scientific interest and a great variety of applications in industry. The growth of scientific interest in zeolites may be measured by the increase in the number of related publications. From the early research on zeolite minerals in 1909 until 1969, over 4500 papers have been published in the open literature. The extensive interest is evidenced equally by over 1000 patents which have been issued in the United States alone. The funda mental properties and applications of molecular sieve zeolites involve many scientific disciplines and cross many of the traditional boundaries. Fields involved are inorganic and physical chemistry with emphasis on surface and colloid chemistry and catalysis, biochemistry, the geological sciences of geochemistry, geology, mineralogy, and physics, including crystallography, spectroscopy, and solid state physics. Applications in the engineering sciences include adsorption separa tions, hydrocarbon catalysis, and purifications. The molecular sieve zeo lites possess many unique properties which have resulted in their use in a great variety of applications such as hydrocarbon conversion catalysts, recovering radioactive ions from waste solutions, separating hydrogen isotopes, solubilizing enzymes, carrying active catalysts in the curing of plastics and rubber, transporting soil nutrients in fertilizers, and even filtering tars from cigarette smoke. Minato has presented an interesting review on industrial uses for mineral zeolites in Japan (65). Relatively 1 Downloaded by UNIV OF NEW ORLEANS on December 9, 2014 |

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Thermal behavior of synthetic faujasite

Cited by 23 publications

References 10 publications

Thermal behaviour of modified faujasites

Thermal behaviour of modified faujasites

Zeolite Y: Synthesis, Modification, and Properties—A Case Revisited

Recent Advances in Zeolite Science

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