In situ Fourier transform infrared spectroscopy study of HY cracking catalysts: Coke formation and the nature of the active sites

Blackmond, Donna G.; Goodwin, James G.; Lester, Joseph E.

doi:10.1016/0021-9517(82)90283-4

Cited by 95 publications

(22 citation statements)

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“…The 1R spectra were obtained by diluting the coked catalyst with KBr and compressing it into a thin wafer. A "coke peak," as reported previously, was present near 1590-1620 cm-' (Eisenbach and Gallei, 1979;Blackmond et al, 1982a). There were other very broad peaks observed below lo00 cm-' that could indicate a complex, plycyclic structure.…”

Section: Resultssupporting

confidence: 72%

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Interparticulate coke formation during hydrocarbon cracking on zeolite catalysts

1983

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A thermogravimetric study of coking of various C6–C7 hydrocarbons on HY and REY zeolites was performed using a Cahn microbalance modified to allow in‐situ measurements of catalyst weight changes during reaction under flow conditions. Mass transfer effects during the reaction were found to play an important role in the coking process of the static catalyst bed. The results indicate that catalytic coke can form in the void space between zeolite particles in such a way as to deter molecular diffusion through the catalyst bed.

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Section: Resultssupporting

confidence: 72%

“…Original studies of coking were mainly concerned with defining regeneration techniques and kinetics. Only in the past fifteen years or so has there been a marked increase in fundamental research in this area rceville, PA. (Langner, 1981;Walsh and Rollman, 1977;Eisenbach and Gallei, 1979;Blackmond et al, 1982aBlackmond et al, . 1982b.…”

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confidence: 99%

Interparticulate coke formation during hydrocarbon cracking on zeolite catalysts

1983

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“…After exposure to the feed gas for 20 min, stretching vibrations that corresponded to the C=C bond of aromatic rings (ñ = 1594, 1572, and 1494 cm À1 ) were observed, which were accompanied by aromatic CÀH stretching bands (ñ = 3040 and 3100 cm À1 ). [22] The intensities of these bands increased gradually with the time on stream, which suggested that the partly dehydrogenated cyclohexane was further dehydrogenated into benzene. The band at ñ = 1643 cm À1 weakened gradually, but it was still observed after 70 min.…”

Section: Resultsmentioning

confidence: 97%

The Unique Role of CaO in Stabilizing the Pt/Al₂O₃ Catalyst for the Dehydrogenation of Cyclohexane

Wang

Ren

et al. 2012

ChemCatChem

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Coke‐induced deactivation is one of the major challenges in the field of heterogeneous catalysis. Herein, the performance of the Pt/Al2O3 catalyst for the hydrogen‐free dehydrogenation of cyclohexane was improved by doping with a small amount of Ca. The Ca‐modified Pt/Al2O3 catalyst exhibited a cyclohexane conversion of 97.0 % and maintained a conversion above 75 % after 48 h, whilst the unmodified catalyst was deactivated from 87.0 to 2.7 % under the same conditions. Characterization techniques, including in situ DRIFT, XPS, thermal analysis, and temperature‐programmed techniques, revealed that the presence of Ca effectively suppressed the deep dehydrogenation of H‐rich carbonaceous components and promoted coke desorption by increasing the H/C ratio of H‐deficient coke. This promotion effect of Ca was also associated with neutralizing the residual Cl ions and promoting immediate dehydrogenation.

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“…Table 5 also shows that Cki(SI) increases significantly as the chain length of the alkene increases from 6 to 8. There is considerable evidence that alkenes are adsorbed at Bronsted sites on solid acid catalysts to produce carbenium ions (Blackmond and Goodwin, 1982). Since the double bond shift occurs easily on zeolites, even at low temperatures, we expect that equilibrium is probably established between the various linear carbenium ion species, at least in the case of short chain length 1-alkenes.…”

Section: Ksicnjmentioning

confidence: 97%

Kinetics and selectivity of reactions of 1‐alkenes on HY zeolite: The influence of chain length

Abbot

Wojciechowski

1988

Can J Chem Eng

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Catalytic reactions of 1‐alkenes on HY have been studied at 400°C. Skeletal isomerization to the corresponding rnonornethylalkene is the dominant initial process. Cracking and coke formation are also observed as initial processes. Initial cracking selectivity can be accounted for by monomolecular β‐scission processes involving a carbenium ion intermediate. However, the initial cracking product distribution for l‐hexene must be explained by assuming some contribution from a dimerization‐cracking mechanism. The kinetics of these processes have been fitted by a model previously used to describe the reactions of n‐alkanes. It is found that the rate constants for both skeletal isomerization and cracking increase with chain length of the feed alkene.

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In situ Fourier transform infrared spectroscopy study of HY cracking catalysts: Coke formation and the nature of the active sites

Cited by 95 publications

References 22 publications

Interparticulate coke formation during hydrocarbon cracking on zeolite catalysts

Interparticulate coke formation during hydrocarbon cracking on zeolite catalysts

The Unique Role of CaO in Stabilizing the Pt/Al₂O₃ Catalyst for the Dehydrogenation of Cyclohexane

Kinetics and selectivity of reactions of 1‐alkenes on HY zeolite: The influence of chain length

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In situ Fourier transform infrared spectroscopy study of HY cracking catalysts: Coke formation and the nature of the active sites

Cited by 95 publications

References 22 publications

Interparticulate coke formation during hydrocarbon cracking on zeolite catalysts

Interparticulate coke formation during hydrocarbon cracking on zeolite catalysts

The Unique Role of CaO in Stabilizing the Pt/Al2O3 Catalyst for the Dehydrogenation of Cyclohexane

Kinetics and selectivity of reactions of 1‐alkenes on HY zeolite: The influence of chain length

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The Unique Role of CaO in Stabilizing the Pt/Al₂O₃ Catalyst for the Dehydrogenation of Cyclohexane