Impact of the local environment of Brønsted acid sites in ZSM-5 on the catalytic activity in n-pentane cracking

Schallmoser, Stefan; Ikuno, Takaaki; Wagenhofer, Manuel; Kolvenbach, Robin; Haller, Gary L.; Sanchez‐Sanchez, Maricruz; Lercher, Johannes A.

doi:10.1016/j.jcat.2014.05.004

Cited by 178 publications

(144 citation statements)

References 33 publications

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“…The samples ZSM‐5(100 °C) and ZSM‐5(120 °C) include mostly crystalline ( 27 Al NMR: δ =53 ppm) and some amorphous material with five‐ ( 27 Al NMR: δ =29 ppm) and six‐fold ( 27 Al NMR 7 ppm) coordination. It seems that the amorphous aluminosilicate phase formed during low temperature crystallization does not contain a lot of OH groups since only zeolite framework bands were found in the corresponding IR spectra …”

Section: Resultsmentioning

confidence: 84%

Tuning Zeolite Properties for a Highly Efficient Synthesis of Propylene from Methanol

Palčić

Ordomsky

Qin

et al. 2018

Chemistry A European J

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A series of nanosized ZSM-5 samples was synthesized at 170, 150, 120, and 100 °C. Experimental data show that the decrease of crystallization temperature leads to significant changes in zeolite properties. Crystals synthesized at 100 °C exhibit many framework defects with lower acid-site density, strength, and a larger external surface area. The selectivity to light olefins and the propylene-to-ethylene ratio increases as the crystallization temperature decreases. A propylene-to-ethylene ratio of above 6 with the highest selectivity to propylene of 53 % was obtained over ZSM-5 catalyst prepared at 100 °C. The stability of the nanosized zeolite in methanol to olefins (MTO) was also improved compared to the industrial sample with a similar Si/Al ratio. This catalytic performance is a result of the decrease in the acid-site density, strength, and the crystals' size, providing a shorter diffusion path and larger external surface area. The presence of structural defects and a different external surface in the crystals has been shown to play an important role in the MTO catalyst performance.

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Section: Resultsmentioning

confidence: 84%

Tuning Zeolite Properties for a Highly Efficient Synthesis of Propylene from Methanol

Palčić

Ordomsky

Qin

et al. 2018

Chemistry A European J

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“…The hydroxyl stretching region of the FT‐IR spectra as well as the FT‐IR spectra obtained after pyridine adsorption (further denoted as Py‐FT‐IR) for the fresh and spent Ru/H‐ZSM‐5 catalysts are shown in Figure a,c. In the hydroxyl region, three main features can be seen, corresponding to hydroxyl groups assigned as BAS at 3602 cm −1 , as LAS at 3662 cm −1 and as terminal FAL silanol groups at 3735 cm −1 . Only the BAS at 3602 cm −1 were found to decrease in intensity for zeolite ZSM‐5‐S‐EHA, indicating some loss of these species during the catalytic reaction in EHA.…”

Section: Fitted Peak Parameters and Intensities For The Solid‐state Nmentioning

confidence: 96%

“…This suggests the transition of FAL species to distorted FAL species, again thought to be the result of the coordination of dealuminated EFAL to FAL. The main change in Al speciation after catalysis is therefore the transition of four‐coordinated, symmetric FAL (Al IV ‐M) to distorted FAL (Al IV ‐L), together with some minor dealumination, mainly of EFAL species …”

Section: Fitted Peak Parameters and Intensities For The Solid‐state Nmentioning

confidence: 99%

“…[28,33,47] In this respect, it seems more likely that the Al IV -L signali st he result of EFAL speciesp resenti nt he MFI pores with coordination to FALc ausing the distortion. [48][49][50][51] 27 Al 3QMAS NMR of H-Y,a nd they assigned this distorted signal to EFAL speciesA l(OH) 2 + . [50] The Al VI -M species shows the standard parameters for six-coordinated extra-framework aluminuma toms (EFAl, diso around 0ppm and as mallC Q of 1.6 MHz) and can be assigned to octahedralE FAL Al(OH) 3 (H 2 O) 3 ;f or the other octahedral Al VI -L species with the larger C Q of 5.56 MHz, distorted EFAL or three-coordinated FAL speciesw ith three additionally adsorbed water molecules have been suggested.…”

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confidence: 99%

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Influence of Levulinic Acid Hydrogenation on Aluminum Coordination in Zeolite‐Supported Ruthenium Catalysts: A ²⁷Al 3QMAS Nuclear Magnetic Resonance Study

Luo

Eck²,

Bruijnincx

et al. 2017

ChemPhysChem

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The influence of a highly oxygenated, polar protic reaction medium, that is, levulinic acid in 2‐ethylhexanoic acid, on the dealumination of two zeolite‐supported ruthenium catalysts, namely Ru/H‐β and Ru/H‐ZSM‐5, has been investigated by 27Al triple‐quantum magic‐angle spinning nuclear magnetic resonance spectroscopy (3QMAS NMR). Upon use of these catalysts in the hydrogenation of levulinic acid, the heterogeneity in aluminum speciation is found to increase for both Ru/H‐ZSM‐5 and Ru/H‐β. For Ru/H‐ZSM‐5, the symmetric, tetrahedral framework aluminum species (FAL) were found to be mainly converted into distorted tetrahedral FAL species, with limited loss of aluminum to the solution by leaching. A severe loss of both FAL and extra‐framework aluminum (EFAL) species into the liquid phase was observed for Ru/H‐β instead. The large decrease in tetrahedral FAL species, in particular, results in a significant decrease in strong acid sites, as corroborated by Fourier transform infrared spectroscopy (FT‐IR). This decrease in acidity, evidence of the inferior stability of the strongly acidic sites in Ru/H‐β relative to Ru/H‐ZSM‐5 under the applied conditions, is considered as the main reason for differences seen in catalyst performance.

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“…as weak Brønsted or Lewis acidic sites or adsorption sites, respectively. [20] Especially Lewis acidic sites are generated during processes such as dehydroxylation during thermal treatment or different postsynthetic dealumination techniques, compare below. [21,22] EFSPE can influence the geometric as well as the chemical properties of H-ZSM-5.…”

Section: Impact and Chemical Nature Of Extra-lattice Speciesmentioning

confidence: 99%

Durability improvements of H-ZSM-5 zeolite for ethanol conversion after treatment with chelating agents

Däumer

Seifert

Reschetilowski

2016

Microporous and Mesoporous Materials

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Impact of the local environment of Brønsted acid sites in ZSM-5 on the catalytic activity in n-pentane cracking

Cited by 178 publications

References 33 publications

Tuning Zeolite Properties for a Highly Efficient Synthesis of Propylene from Methanol

Tuning Zeolite Properties for a Highly Efficient Synthesis of Propylene from Methanol

Influence of Levulinic Acid Hydrogenation on Aluminum Coordination in Zeolite‐Supported Ruthenium Catalysts: A ²⁷Al 3QMAS Nuclear Magnetic Resonance Study

Durability improvements of H-ZSM-5 zeolite for ethanol conversion after treatment with chelating agents

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Impact of the local environment of Brønsted acid sites in ZSM-5 on the catalytic activity in n-pentane cracking

Cited by 178 publications

References 33 publications

Tuning Zeolite Properties for a Highly Efficient Synthesis of Propylene from Methanol

Tuning Zeolite Properties for a Highly Efficient Synthesis of Propylene from Methanol

Influence of Levulinic Acid Hydrogenation on Aluminum Coordination in Zeolite‐Supported Ruthenium Catalysts: A 27Al 3QMAS Nuclear Magnetic Resonance Study

Durability improvements of H-ZSM-5 zeolite for ethanol conversion after treatment with chelating agents

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Influence of Levulinic Acid Hydrogenation on Aluminum Coordination in Zeolite‐Supported Ruthenium Catalysts: A ²⁷Al 3QMAS Nuclear Magnetic Resonance Study