Dissolution of high-silica zeolites in alkaline solutions II. Dissolution of ‘activated’ silicalite-1 and ZSM-5 with different aluminum content

Čimek, Ankica; Subotić, Boris; Šmit, Ivan; Tonejc, Antun; Aiello, R.; Crea, F.; Nastro, A.

doi:10.1016/s0927-6513(96)00082-x

Cited by 112 publications

(63 citation statements)

References 12 publications

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“…Figure 2a shows that, in line with findings of ižmek et al, 40 yields reduced with increasing NaOH concentration and Si/Al ratio of the parent zeolite. The yields for Z40…”

Section: Two-dimensional Screening Of Desilicationsupporting

confidence: 87%

Full Compositional Flexibility in the Preparation of Mesoporous MFI Zeolites by Desilication

et al. 2011

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We demonstrate that desilication in alkaline medium is a suitable post-synthetic method to introduce intracrystalline mesoporosity in MFI zeolites independent of the Si/Al ratio in the parent material. By systematic screening of the influence of both base concentration (0.1-1.8 M NaOH) and Si/Al ratio (10-1000) on the properties of the treated zeolites, we reveal that effective mesoporosity introduction Hierarchical ZSM-5 after acid washing stands as the most active sample, which stresses the relevance of the additional post-synthesis treatment step.

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“…Figure 2a shows that, in line with findings of ižmek et al, 40 yields reduced with increasing NaOH concentration and Si/Al ratio of the parent zeolite. The yields for Z40…”

Section: Two-dimensional Screening Of Desilicationsupporting

confidence: 87%

Full Compositional Flexibility in the Preparation of Mesoporous MFI Zeolites by Desilication

et al. 2011

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“…The absence of particles resembling the partially dissolved EMT-A and EMT-B samples in the SEM images of all FAU-on-EMT overgrowth materials supports this hypothesis. The distribution of Si(nAl) environments in the EMT support crystals and in some selected FAU-on-EMT overgrowth samples was determined with 29 Si MAS NMR. The 29 Si MAS NMR spectrum of the EMT support crystals is shown in Figure 11, a.…”

Section: Characterization Of Both the Fau And The Emt Phasementioning

confidence: 99%

“…300 nm. The compositional difference between the EMT support and the FAU film was investigated with 29 Si magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and energy-dispersive analysis of X-rays (nano-EDAX). The continuous nature of the film was confirmed by the absence of intracrystalline mesopores, which was evidenced by nitrogen physisorption.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Characterization of Epitaxial FAU-on-EMT Zeolite Overgrowth Materials

Goossens

Wouters

Grobet

et al. 2001

Eur. J. Inorg. Chem.

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Epitaxial FAU zeolite films were achieved on micrometer‐sized EMT support crystals using a two‐step synthetic procedure, in which EMT support crystals with hexagonal‐platelet morphology, were added to a synthesis gel for the crystallization of an FAU phase. Identification of the appropriate synthesis parameters made it possible to suppress homogeneous nucleation and initial breeding, and to promote the secondary nucleation of the FAU crystallites on the surface of the EMT support crystals. The presence of both an FAU and an EMT phase was verified with powder X‐ray diffraction (XRD). Scanning electron microscopy (SEM) was used to confirm the formation of a layer of FAU crystallites on the EMT support crystals. The growth of the FAU phase was found to start at the corners and edges of the EMT support. An FAU crystallization front progressed from the edges towards the center of the hexagon until the EMT support crystals became completely covered by an FAU zeolite film with a thickness of ca. 300 nm. The compositional difference between the EMT support and the FAU film was investigated with 29Si magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy, X‐ray photoelectron spectroscopy (XPS) and energy‐dispersive analysis of X‐rays (nano‐EDAX). The continuous nature of the film was confirmed by the absence of intracrystalline mesopores, which was evidenced by nitrogen physisorption.

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“…Hierarchical porosity can be introduced into zeolites via templating and/or desilication; the former being part of zeolite synthesis and the latter a postsynthetic modification [40]. Desilication through treatment with alkaline solutions of Na 2 CO 3 or NaOH selectively removes Si from zeolites [35,37,41]. In a study by Čimek et al, the importance of aluminium removal as a prerequisite to desilication was investigated by varying the dissolution conditions [41].…”

Section: Introductionmentioning

confidence: 99%

“…Desilication through treatment with alkaline solutions of Na 2 CO 3 or NaOH selectively removes Si from zeolites [35,37,41]. In a study by Čimek et al, the importance of aluminium removal as a prerequisite to desilication was investigated by varying the dissolution conditions [41]. The synthesis and application of hierarchical and large pore zeolites has been extensively reviewed [39,40,42,43].…”

Section: Introductionmentioning

confidence: 99%

On the influence of Si:Al ratio and hierarchical porosity of FAU zeolites in solid acid catalysed esterification pretreatment of bio-oil

Osatiashtiani

Puértolas

Oliveira

et al. 2017

Biomass Conv. Bioref.

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A family of faujasite (FAU) zeolites with different Si:Al ratio, and/or hierarchical porosity introduced via postsynthetic alkaline desilication treatment, have been evaluated as solid acid catalysts for esterification pretreatments of pyrolysis bio-oil components. Acetic acid esterification with aliphatic and aromatic alcohols including methanol, anisyl alcohol, benzyl alcohol, p-cresol and n-butanol was first selected as a model reaction to identify the optimum zeolite properties. Materials were fully characterised using N 2 porosimetry, ICP, XRD, XPS, FT-IR, pyridine adsorption, NH 3 TPD, In-situ ATR and inverse gas chromatography (IGC). IGC demonstrates that the surface polarity and hence hydrophobicity of FAU decreases with increased Si:Al ratio. Despite possessing a higher acid site loading and acetic acid adsorption capacity, high Al-content FAU possess weaker acidity than more siliceous catalysts. Esterification activity increases with acid strength and decreasing surface polarity following the order FAU30>FAU6>FAU2.6. The introduction of mesoporosity through synthesis of a hierarchical HFAU30 material further enhances esterification activity through improved acid site accessibility and hydrophobicity. Methanol was the most reactive alcohol for esterification, and evaluated with HFAU30 for the pretreatment of a real pyrolysis bio-oil, reducing the acid content by 76% under mild conditions.

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Dissolution of high-silica zeolites in alkaline solutions II. Dissolution of ‘activated’ silicalite-1 and ZSM-5 with different aluminum content

Cited by 112 publications

References 12 publications

Full Compositional Flexibility in the Preparation of Mesoporous MFI Zeolites by Desilication

Full Compositional Flexibility in the Preparation of Mesoporous MFI Zeolites by Desilication

Synthesis and Characterization of Epitaxial FAU-on-EMT Zeolite Overgrowth Materials

On the influence of Si:Al ratio and hierarchical porosity of FAU zeolites in solid acid catalysed esterification pretreatment of bio-oil

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