ChemInform Abstract: Spectroscopic and Physicochemical Characterization of P‐Modified H‐ZSM‐ 5.

Lischke, G.; Eckelt, Reinhard; Jerschkewitz, H.-G.; Parlitz, B.; Schreier, E.; Storek, W.; Zibrowius, Bodo; Oehlmann, G.

doi:10.1002/chin.199203025

Cited by 13 publications

(85 citation statements)

References 1 publication

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“…[6][7][8][9][10][11][12] Even though there is still some debate on the effect of acid site strength on the MTO product distribution, the promoting effect of phosphorus on the hydrothermal stability of H-ZSM-5 is undisputed. 4,9,[13][14][15][16][17][18][19][20][21][22][23][24][25] Zeolite H-ZSM-5 catalysts that contain phosphorus are more stable under hydrothermal conditions i.e. they retain more framework aluminium species and strong acid sites than their non-phosphated counterparts.…”

Section: Introductionmentioning

confidence: 99%

“…Not surprisingly, many models for possible interactions have been discussed over the years, where the main division of opinion lies between the question whether permanent phosphorus-framework interaction exists or not. 14,17,19,[26][27][28][29][30]42 In the case of permanent phosphorus-framework interaction the most intuitive explanation would be the incorporation of phosphorus into the zeolitic framework. However, the Si-O-P bonds that are required for such a substitution have never been found in either phosphorus/H-ZSM-5 or SAPO materials and theoretical work has pointed to the unlikeliness of such bonds.…”

Section: Introductionmentioning

confidence: 99%

“…However, the Si-O-P bonds that are required for such a substitution have never been found in either phosphorus/H-ZSM-5 or SAPO materials and theoretical work has pointed to the unlikeliness of such bonds. 14,15,17,20,[29][30][31][32] Other possibilities of phosphorus-framework interaction have been suggested to arise from protonation of phosphoric acid by zeolitic bridging hydroxyl groups, stabilising the nearest neighbouring aluminium atom. 17 However, due to the low aluminium content generally found in H-ZSM-5, Al-O-Si-O-Al sites are quite rare and theoretical studies excluded the possibility of H 3 PO 4 protonation.…”

Section: Introductionmentioning

confidence: 99%

“…Permanent phosphorusframework interaction was suggested not to exist. 14 Caro and co-workers also proposed that phosphorus only interacted with extra-framework aluminium and that dealumination leads to a decrease in acid sites. 42 These disagreements on zeolite-phosphorus interaction have led to much confusion with regard to the interpretation of data and spectra, as different authors attribute similar peaks to different species, e.g.…”

Section: Introductionmentioning

confidence: 99%

“…in 27 Al MAS NMR and especially 31 P MAS NMR. 14,17,18,42 Another complicating factor is the synthesis conditions used during phosphatation, which vary for different studies. There are three parameters that can affect the structure of the zeolite material, namely (i) acidity coming from the acidic precursor H 3 PO 4 , which is often used, (ii) thermal treatment that is customarily performed after phosphorus introduction, and (iii) the actual presence of phosphorus species.…”

Section: Introductionmentioning

confidence: 99%

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Local silico-aluminophosphate interfaces within phosphated H-ZSM-5 zeolites

Bij

Weckhuysen

2014

Phys. Chem. Chem. Phys.

127

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In order to elucidate phosphorus-zeolite H-ZSM-5 interactions, a variety of phosphorus-modified zeolite H-ZSM-5 materials were studied in a multi-spectroscopic manner. By deploying single pulse 27 Al, 31 P MAS NMR, 2D heteronuclear 27 Al-31 P correlation (HETCOR), 27 Al MQ MAS NMR spectroscopy, TPD of pyridine monitored by FT-IR spectroscopy, and Scanning Transmission X-ray Microscopy (STXM) the interplay and influence of acidity, thermal treatment and phosphorus on the structure and acidity of H-ZSM-5 were established. It was found that while acid treatment did not affect the zeolite structure, thermal treatment leads to the breaking of Si-OH-Al bonds, a decrease in the strong acid site number and the formation of terminal Al-OH groups. No extra-framework aluminium species was observed. Phosphorus precursors interact with the zeolitic framework through hydrogen bonds and physical coordination, as phosphorus species can be simply washed out with hot water. After phosphatation and thermal treatment two effects occur simultaneously, namely (i) phosphorus species transform into water insoluble condensed poly-phosphoric acid and (ii) phosphoric acid binds irreversibly to the terminal Al-OH groups of partially dislodged four-coordinated framework aluminium, forming local silico-aluminophosphate interfaces.These interfaces are potentially the promoters of hydrothermal stability in phosphated zeolite H-ZSM-5.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Local silico-aluminophosphate interfaces within phosphated H-ZSM-5 zeolites

Bij

Weckhuysen

2014

Phys. Chem. Chem. Phys.

127

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Solid‐State MAS NMR Study of Hydrated/Dehydrated Phosphorus‐modified ZSM‐5 Zeolite

Kim

2018

Bulletin Korean Chem Soc

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The chemical changes of the phosphorus-modified ZSM-5 zeolites in hydration/dehydration processes have been studied by using the solid-state MAS NMR spectroscopy. The identification of the chemical species of the steamed or washed zeolite could be done by analyzing the spectral changes on the solid-state multinuclear MAS NMR spectroscopy when the zeolite was hydrated and dehydrated. It was reconfirmed that the steaming process effectively remove Al-attached polyphosphates from the zeolite framework even though the zeolite was modified with phosphorus but the washing process did not. Dehydration process led to a dramatic change of aluminum species by breaking the aluminum-oxygen bond in the zeolite framework and to a formation of polyphosphate attached to aluminum.

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Hexane Cracking over Steamed Phosphated Zeolite H‐ZSM‐5: Promotional Effect on Catalyst Performance and Stability

Bij

Meirer

Kalirai

et al. 2014

Chemistry A European J

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The nature behind the promotional effect of phosphorus on the catalytic performance and hydrothermal stability of zeolite H-ZSM-5 has been studied using a combination of (27) Al and (31) P MAS NMR spectroscopy, soft X-ray absorption tomography and n-hexane catalytic cracking, complemented with NH3 temperature-programmed desorption and N2 physisorption. Phosphated H-ZSM-5 retains more acid sites and catalytic cracking activity after steam treatment than its non-phosphated counterpart, while the selectivity towards propylene is improved. It was established that the stabilization effect is twofold. First, the local framework silico-aluminophosphate (SAPO) interfaces, which form after phosphatation, are not affected by steam and hold aluminum atoms fixed in the zeolite lattice, preserving the pore structure of zeolite H-ZSM-5. Second, the four-coordinate framework aluminum can be forced into a reversible sixfold coordination by phosphate. These species remain stationary in the framework under hydrothermal conditions as well. Removal of physically coordinated phosphate after steam-treatment leads to an increase in the number of strong acid sites and increased catalytic activity. We propose that the improved selectivity towards propylene during catalytic cracking can be attributed to local SAPO interfaces located at channel intersections, where they act as impediments in the formation of bulky carbenium ions and therefore suppress the bimolecular cracking mechanism.

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ChemInform Abstract: Spectroscopic and Physicochemical Characterization of P‐Modified H‐ZSM‐ 5.

Cited by 13 publications

References 1 publication

Local silico-aluminophosphate interfaces within phosphated H-ZSM-5 zeolites

Local silico-aluminophosphate interfaces within phosphated H-ZSM-5 zeolites

Solid‐State MAS NMR Study of Hydrated/Dehydrated Phosphorus‐modified ZSM‐5 Zeolite

Hexane Cracking over Steamed Phosphated Zeolite H‐ZSM‐5: Promotional Effect on Catalyst Performance and Stability

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