Coke Formation and Its Effects on Shape Selective Adsorptive and Catalytic Properties of Ferrierite

Xu, Wenqing; Ye, Yin; Suib, Steven L.; O’Young, Chi-Lin

doi:10.1021/j100002a045

Cited by 88 publications

(51 citation statements)

References 8 publications

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“…Once the deposits were totally converted to unreactive species, the intrinsic high selectivity of the H-FER was recovered. Note that the current proposal on the role of aromatics formation differs significantly from that of the role of coke reported in other studies (4,(10)(11)(12)(13)(14), in which coke was suggested to hinder oligomers formation by restricting pore dimension or blocking unselective acid sites. On the contrary, our experimental findings strongly support the model recently reported by de Jong et al (8).…”

Section: Relation Between the Carbonaceous Deposits And The Catalyticcontrasting

confidence: 95%

“…The catalyst was transformed into the ammonium form by successive ion exchange with a 1-M NH 4 NO 3 solution at room temperature. The ammonium form of the catalyst was heat-treated for 6 h ex situ at 823 K in flowing N 2 , and further outgassed in situ at 823 K for 1 h before use.…”

Section: Catalystmentioning

confidence: 99%

“…Such deactivation can occur by direct poisoning of the active sites or by blockage of the pores of the catalytic material (1)(2)(3)(4). It has also been proposed that the carbonaceous deposits could act as catalytic entities (5)(6)(7)(8), and in this respect, the deposits formed in the case of the skeletal isomerization of n-butenes over H-FER catalysts have raised a lot of interest and controversy.…”

Section: Introductionmentioning

confidence: 99%

“…Guisnet et al suggested that the isobutene yield was related to the formation of aromatic (5) or tert-butyl (9) carbocations, which catalyzed butene isomerization via a pseudomonomolecular mechanism. However, other authors proposed that the main role of these deposits was to deactivate nonselective sites and/or to increase steric constraint within the microporous solid (4,(10)(11)(12)(13)(14). De Jong et al recently proposed yet another model, in which reactive aliphatic carbonaceous deposits initially yield by-products before being converted to more inert aromatics (8).…”

Section: Introductionmentioning

confidence: 99%

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In Situ IR Study of the Nature and Mobility of Sorbed Species on H-FER during But-1-ene Isomerization

Meunier

Domokos

Seshan

et al. 2002

Journal of Catalysis

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The sorption and reaction of but-1-ene over a ferrierite sample was studied by in situ IR spectroscopy to relate the selectivity to isobutene and the sorbed species. The spectra highlighted the presence of various unsaturated species including polyenes, which were readily formed upon contacting H-FER with but-1-ene while a poor selectivity to isobutene was observed. Aromatic compounds were concluded to be subsequently formed via dehydrogenation/cyclization of the polyenic deposits while the isobutene selectivity increased via suppression of by-products. These data support earlier assumptions that the initial high yield of by-products was produced by the reaction of butenes with reactive deposits, which were gradually converted into more inert aromatic deposits. Upon purging the catalyst with an inert, branched C 8 hydrocarbons and aromatic molecules such as xylenes desorbed. The rates of desorption showed an initially linear variation with the square root of time and were fitted to a monodimensional Fickian model. Because the slowly diffusing species were rather abundant during the course of the reaction, it is proposed that the skeletal isomerization was effectively limited to the acid sites close the pore mouth of H-FER crystallites. c 2002 Elsevier Science (USA)

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Section: Relation Between the Carbonaceous Deposits And The Catalyticcontrasting

confidence: 95%

Section: Catalystmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

In Situ IR Study of the Nature and Mobility of Sorbed Species on H-FER during But-1-ene Isomerization

Meunier

Domokos

Seshan

et al. 2002

Journal of Catalysis

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“…The twodimensional zeolite H-ferrierite (H-FER), for which 8-MR pores interconnect the 10-MR main channels, displays an exceptionally high selectivity and stability (5,6). Nevertheless, the initial selectivity of H-FER is low, but increases with time onstream (TOS) when carbonaceous deposits largely fill the H-FER pores (4,(7)(8)(9). Over a fresh catalyst 13 C-labeling experiments have proven that nonselective bimolecular reactions, i.e., dimerization followed by cracking, dominate the catalytic action.…”

Section: Introductionmentioning

confidence: 99%

Probing the Accessible Sites for n-Butene Skeletal Isomerization over Aged and Selective H-Ferrierite with d3-Acetonitrile

Donk

Bus

Broersma

et al. 2002

Journal of Catalysis

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Aged H-ferrierite (H-FER) samples with different contents of de-posits were prepared and studied under differential catalytic conditions in a tapered element oscillating microbalance. Subsequently, these samples were examined using infrared spectroscopy to determine the nature of carbonaceous deposits and probing the type and number of accessible sites with d 3 -acetonitrile. From these results, for the first time, we have been able to calculate turnover frequencies (TOFs) for n-butene conversion and isobutene formation for both fresh and aged H-FER catalysts. It is observed that the deposition of carbonaceous species significantly lowers the number of accessible Brønsted sites. With short time on stream (TOS), cracking of the alkyl-aromatic deposits contributes to the overall isobutene production but simultaneously harms the selective catalytic action by inducing nonselective side reactions. With prolonged TOS these deposits become nonreactive and as a result the TOF drops, while isobutene is produced with high selectivity. It is demonstrated that at this stage no carbenium ions are detected, while Brønsted OH acid sites are still accessible for d 3 -acetonitrile on the extensively aged and highly selective H-FER. This indicates that the latter sites are responsible for the selective catalytic conversion of n-butene into isobutene. c 2002 Elsevier Science (USA)

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Monitoring the Location, Amount, and Nature of Carbonaceous Deposits on Aged Zeolite Ferrierite Crystals by Using STEM‐EELS

Donk

Groot

Stéphan

et al. 2003

Chemistry A European J

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By the use of electron energyloss spectroscopy performed in a scanning transmission electron microscope (STEM-EELS), detailed spatial information is obtained concerning the amount and nature of carbonaceous deposits formed inside the crystals of the zeolite ferrierite (FER) during the reaction of n-butene to isobutene. In all cases, gradients in coke concentration over the crystal have been observed and quantified. An extensive accumulation of coke is observed at the entrance of the eight-membered-ring (MR) pores, while less coke is present at the entrances of the ten-MR channels. At a higher coke content, further filling up of the complete micropore system occurs and the eight-MR pores become fully blocked. The ten-MR channels remain partially accessible for n-butene, with alkyl-aromatic species deposited near the inlets of these channels. With regard to the selective transformation of nbutene into isobutene, this supports the view that the catalytic action takes place in the pore mouths of the ten-MR channels. Overall it is demonstrated that the major benefit of STEM-EELS is the possibility to simultaneously determine the position-resolved amount and nature of carbonaceous deposits on intact zeolite crystals.

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Coke Formation and Its Effects on Shape Selective Adsorptive and Catalytic Properties of Ferrierite

Cited by 88 publications

References 8 publications

In Situ IR Study of the Nature and Mobility of Sorbed Species on H-FER during But-1-ene Isomerization

In Situ IR Study of the Nature and Mobility of Sorbed Species on H-FER during But-1-ene Isomerization

Probing the Accessible Sites for n-Butene Skeletal Isomerization over Aged and Selective H-Ferrierite with d3-Acetonitrile

Monitoring the Location, Amount, and Nature of Carbonaceous Deposits on Aged Zeolite Ferrierite Crystals by Using STEM‐EELS

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