Hydrothermal decomposition of aluminosilicate zeolites and prediction of their long-term stability

Ehrhardt, K.; Suckow, M.; Lutz, W.

doi:10.1016/s0167-2991(06)81220-6

Cited by 25 publications

(19 citation statements)

References 6 publications

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“…This phenomenon was checked in this series that utilizes the sodium and proton modifications of a FAU zeolite. Whereas the Na-modification is nearly unchanged up to its collapse above 513 K (Ehrhardt et al, 1995), the H-modification is decomposed beginning already at 403 K (Fig. 3).…”

Section: Resultsmentioning

confidence: 98%

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Investigation and Modeling of the Hydrothermal Stability of Technically Relevant Zeolites

et al. 2005

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The dense-structured zeolites of types ZSM-5 (MFI) and mordenite (MOR) of different SiO 2 /Al 2 O 3 moduli are relatively stable under treatment by liquid water for 72 hours up to 513 K. The open-structured zeolites of types Y in dealuminated modification (FAU) and beta (BEA) undergo strong decomposition in the same range. For these two sample types a mathematical model for the decomposition of the zeolite framework is established that takes into account the influence of modulus as well as temperature. Here the kinetic of the solid phase reaction is a superposition of two different mechanisms described by the Monod equation.

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Section: Resultsmentioning

confidence: 98%

“…The function g(w) characterizes the influence of steam pressure in the system, and it is assumed that it can be defined as a n-th order dependency of normalized steam concentration (Ehrhardt et al, 1995) …”

Section: Modelingmentioning

confidence: 99%

Investigation and Modeling of the Hydrothermal Stability of Technically Relevant Zeolites

et al. 2005

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“…Content of extraframework species in steamed DAY samples [77] amounted to 0.6-4.9% for the aluminosilicate ( ) and 4.3-14,7% for silica gel ( ). It has been shown [83,84] that the intensity of the peaks assigned to and at lowtemperature steaming could be reduced by successive chemical dissolution in hydrochloric acid and solution of potassium hydroxide. Acid treatment caused the decomposition of the Al aluminosilicate with formation of silica gel.…”

Section: Extraframework Species In Steamed Y Zeolitesmentioning

confidence: 99%

“…Then, with the rising temperature, carnegiiete and nepheline occur above 1123 K [4,10]. In water or steam of autogenous pressure, NaY is stable up to 513 K [83]. It will be decomposed into an amorphous phase followed by transformation into hydroxysodalite or zeolite P [89,90].…”

Section: Origin Of Siliceous Extraframework Species Zeolitementioning

confidence: 99%

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

Lutz

2014

Advances in Materials Science and Engineering

142

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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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“…Several studies have been carried out on the hydrothermal stability of zeolite LTA and FAU (Wolf et al 1967;Lutz et al 1983Lutz et al , 1988Lutz et al , 2005Richtermendau et al 1988;Fichtner-Schmittler et al 1992;Ehrhardt et al 1995;Buhl et al 2004;Dimitrijevic et al 2006). In these publications, a relation between the susceptibility of zeolites to hydrothermal damage and the Si/Al-ratio, as well as the dependency on the cation size in ion-exchanged zeolites was established (Buhl et al 2004;Fichtner-Schmittler et al 1992).…”

Section: Introductionmentioning

confidence: 99%

Hydrothermal stability of pelletized zeolite 13X for energy storage applications

et al. 2008

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Three samples of pelletized zeolite Na-13X from different industrial suppliers were hydrothermally treated in an open system for up to 3500 adsorption/desorption cycles. Before and after this aging procedure, the samples have been characterized by water uptake measurements, X-ray powder diffraction (XRD), Hg-porosimetry, N 2 -and CO 2 -adsorption and small-angle X-ray scattering (SAXS). Large differences in the degree of degradation were found between the different materials: The adsorbent with the best performance maintains 79% of its original water uptake capacity after 3500 cycles, whereas this value is reduced to 65% after only 1600 cycles in case of the most unstable sample. For all materials, the residual water adsorption capacity was found to be higher than it was to expect from XRD data. In addition to structural changes of the zeolite cages, Hg-porosimetry and SAXS reveal a modification of the sample morphology in the meso-and macropore range. CO 2 adsorption experiments evidence that as a result of the aging process mass transfer kinetics are slowed down significantly.These findings indicate that the influence of hydrothermal treatment on the water adsorption performance not only depends on the crystal structure of the actual adsorbent, but is indeed a result of a complex interplay with the system of larger pores. The crucial role of the binder material is underlined by the fact that the most stable sample was produced by a so-called binder-free method.

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Hydrothermal decomposition of aluminosilicate zeolites and prediction of their long-term stability

Cited by 25 publications

References 6 publications

Investigation and Modeling of the Hydrothermal Stability of Technically Relevant Zeolites

Investigation and Modeling of the Hydrothermal Stability of Technically Relevant Zeolites

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

Hydrothermal stability of pelletized zeolite 13X for energy storage applications

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