Centimeter-sized zeolite bodies of intergrown crystals: Preparation, characterization and study of binder evolution

Itani, Lama; Valtchev, Valentin; Patarin, Joël; Rigolet, Séverinne; Gao, Feifei; Baudin, Gérard

doi:10.1016/j.micromeso.2010.09.011

Cited by 21 publications

(17 citation statements)

References 30 publications

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“…For all isotherms shown in Figure (right) no further gas uptake is observed once the saturation plateau is reached. Thus, the shaping procedure developed in this work did not generate voids in the mesoporous regime (2–50 nm) which was previously reported for zeolite beta monoliths prepared with alumina binder . The N 2 saturation plateau is reduced with increasing binder content.…”

Section: Resultssupporting

confidence: 73%

“…The most commonly used binder is polyvinyl alcohol (PVA) but also biopolymers such as sucrose, alginate,, or chitosan were considered for MOF shaping. Other approaches make use of inorganic binders like bentonite, silica sol, or alumina that are traditionally employed for the production of shaped zeolites and mesoporous silicas . The mechanical stability of shaped MOFs is usually increasing with higher binder content.…”

Section: Introductionmentioning

confidence: 99%

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Shaping of Flexible Metal‐Organic Frameworks: Combining Macroscopic Stability and Framework Flexibility

et al. 2019

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A facile extrusion approach that can fully retain the breathing behavior of flexible metal-organic frameworks (MOF) like MIL-53 and MIL-53-NH 2 employing methyl cellulose as binder is reported. Shaped MOF extrudates were extensively characterized by nitrogen sorption, X-ray diffraction, thermogravimetric analysis and scanning electron microscopy. A detailed study on the mechanical stability of MIL-53 extrudates with different amounts of binder reveals an increase in stability at low binder fractions while the maximum in attainable stabil- [a] 4700 Figure 2. Powder X-ray diffraction patterns of produced MIL-53 extrudates with different amounts of MC 400 (left). Nitrogen adsorption isotherms at 77 K of the MIL-53 extrudates in comparison to the parent powder (right). Desorption branches are excluded for clarity.

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Section: Resultssupporting

confidence: 73%

Section: Introductionmentioning

confidence: 99%

Shaping of Flexible Metal‐Organic Frameworks: Combining Macroscopic Stability and Framework Flexibility

et al. 2019

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“…The preparation of zeolite‐based industrial catalysts usually involves mixing the zeolites with silica and or alumina binders in order to dilute the zeolite properties and to obtain the desired throughput . During this process it is assumed that the zeolite crystals themselves are homogeneous in nature, that is, only small variations in properties between the zeolite crystals in a batch exist. However, if this assumption is wrong and large variations in, for example, acid site density are present, parts of the shaped catalyst could become more active than others, resulting in undesired coke formation and thus a loss in catalyst activity and lifetime …”

Section: Figurementioning

confidence: 99%

Assessing Inter and Intra‐particle Heterogeneity in Alumina‐poor H‐ZSM‐5 Zeolites

et al. 2017

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We reveal the presence of significant variations in Brønsted catalytic activity within and between individual H-ZSM-5 zeolite crystals. Fluorescence microscopy in combinationw ith a fluorogenic probe was used to resolve the catalytic activity at the nanoscale. The observed variations in catalytic activity could be directly linked to structural parameters and crystal morphology observed in scanninge lectron microscopy and by specifically stainingc rystal defects. The obtained resultsa re directly comparedw ith ensemblea veraged information from techniques such as pyridine IR spectroscopy and nitrogen physisorption, typically used to characterize acid zeolites. The inter-and intra-particle heterogeneities resolved by the employed fluorescence approach remainu naddressed by bulk characterization. Our experimental resultsr elate the heterogeneous catalytic activity to variation in both the Si/Al ratio and mesoporosity inducedd uring the zeolite synthesis.The preparation of zeolite-based industrial catalysts usually involves mixingt he zeolitesw ith silicaa nd or aluminab inders in order to dilute the zeolite properties and to obtain the desired throughput. [1][2][3] During this process it is assumed that the zeolite crystalsthemselves are homogeneous in nature, [2,4,5] that is, only small variations in properties between the zeolite crystals in ab atch exist. However,i fthis assumption is wrong and large variations in, for example, acid site density are present, parts of the shaped catalystc ould become more active than others,r esulting in undesired coke formation and thus al oss in catalystactivity and lifetime. [4,6,7] Twop arameters impacting catalyst activity are the number and strength of acid sites present in az eolite. These are directly relatedt ot he framework Al content, [8,9] hence Al determination is often used to assess zeolite acidity.S everalt echniques can be used to determine the Si/Al ratio, yielding powder averaged information, for example, elemental analysisu sing inductive coupled plasma (ICP), [10,11] magic angle spinning (MAS) 29 Si and 27 Al NMR, [8,12] laser induced break down spectroscopy (LIBS), [13] X-ray photon electron spectroscopy (XPS) [12,14] and time of flight-secondary ion mass spectrometry (TOF-SIMS). [15,16] All of theset echniques lead to the determination of the 'bulk" scale acidity and some are even able to obtain single crystal information given that crystal sizes and aluminum content are sufficiently large; [17] for example, single crystal X-ray diffraction [17,18] and energy dispersive X-ray spectroscopy (EDX) coupled to electron microscopy potentially with focused-ion-beam milling. [14,19] In summary,t he acidic properties of zeolitesa re often deduced indirectly from the aluminum content.F urther,n oi nformation regarding site accessibility is obtained in these results. Direct measurements of acid site density and strengtha re possible via temperature programmed desorption (TPD) [8,14,20] and infrared- [2,21,22] or Raman spectroscopy [23] using basic probe molecules such...

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“…However, binders are necessary to improve the mechanical properties and to allow for the compression of powders. In the literature, significant amounts of binder is used to shape zeolites, leading to objects (e.g., cylinders, beads) with high mechanical resistance and optimal dimensions [20–24]. In the literature, the use of a hydraulic press to form zeolite pellets is not common, although some articles have been published [24–25].…”

Section: Introductionmentioning

confidence: 99%

“…In the literature, significant amounts of binder is used to shape zeolites, leading to objects (e.g., cylinders, beads) with high mechanical resistance and optimal dimensions [20–24]. In the literature, the use of a hydraulic press to form zeolite pellets is not common, although some articles have been published [24–25]. Moreover, the mechanical resistance (compression tests) is either low (between 1 and 10 MPa) or the amount of binder is very high (more than 20 wt %) [20–25].…”

Section: Introductionmentioning

confidence: 99%

Prediction of the mechanical properties of zeolite pellets for aerospace molecular decontamination applications

Rioland¹,

Dutournié²,

Faye³

et al. 2016

Beilstein J. Nanotechnol.

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Zeolite pellets containing 5 wt % of binder (methylcellulose or sodium metasilicate) were formed with a hydraulic press. This paper describes a mathematical model to predict the mechanical properties (uniaxial and diametric compression) of these pellets for arbitrary dimensions (height and diameter) using a design of experiments (DOE) methodology. A second-degree polynomial equation including interactions was used to approximate the experimental results. This leads to an empirical model for the estimation of the mechanical properties of zeolite pellets with 5 wt % of binder. The model was verified by additional experimental tests including pellets of different dimensions created with different applied pressures. The optimum dimensions were found to be a diameter of 10–23 mm, a height of 1–3.5 mm and an applied pressure higher than 200 MPa. These pellets are promising for technological uses in molecular decontamination for aerospace-based applications.

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Centimeter-sized zeolite bodies of intergrown crystals: Preparation, characterization and study of binder evolution

Cited by 21 publications

References 30 publications

Shaping of Flexible Metal‐Organic Frameworks: Combining Macroscopic Stability and Framework Flexibility

Shaping of Flexible Metal‐Organic Frameworks: Combining Macroscopic Stability and Framework Flexibility

Assessing Inter and Intra‐particle Heterogeneity in Alumina‐poor H‐ZSM‐5 Zeolites

Prediction of the mechanical properties of zeolite pellets for aerospace molecular decontamination applications

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