Infrared spectroscopic investigations relating to coke formation on zeolites I. Adsorption of hexene-1 and n-hexane on zeolites of type Y

Eisenbach, D.; Gallei, E.

doi:10.1016/0021-9517(79)90130-1

Cited by 141 publications

(18 citation statements)

References 12 publications

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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: 73%

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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: 73%

“…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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“…The clay turned black during the higher temperature reactions. The appearance of the clay was suggestive of coke formation, as has been observed for many systems (see, e.g., Eisenbach and Gallei, 1979).…”

Section: Reactions Of Butadienesupporting

confidence: 69%

Reactions of the Conjugated Dienes Butadiene and Isoprene Alone and with Methanol Over Ion-Exchanged Montmorillonites

Adams

1986

Clays and clay miner.

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Abstract--The reactions of simple conjugated dienes over divalent and trivalent transition metal-exchanged montmorillonites yield, in the absence of nucleophiles, a variety of products. Some of these products are a result of Diels-Alder cycloaddition reactions, whereas others are indicative of carbocation intermediates, i.e., other dimers, oligomer8, and isomerization products of these intermediates. The reactions in sealed cells between 20 ~ and 150"C show trends in the yields of the various product groups. Dimers of butadlene and isoprene formed by cycloaddition (i.e., 4-vinylcyclohexene and the monoterpene p-menthadiene (limonene)) were formed at low temperatures (20-50~ As the temperature was raised, the total yield of dimers increased and higher oligomers were formed along with isomerization products of the dimers and oligomers. The products of cycloaddition, however, did not increase markedly. The type of solvent used for the reaction was found to influence the reactivity, e.g., the use of 1,4-dioxan rather than chloroform led to a reduction in total conversion and also to a markedly higher degree of selectivity. In the presence of a suitable nucleophile (methanol), both dienes gave the 1,4-addition product predominantly, which suggests that an allylic carbocation intermediate was involved. The use of an interlayer-supported nickel complex, [HNi(P(OEt)3)4] § produced the only large scale polymerization observed in this work.

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“…As shown in Figure , there are two major adsorption bands observed at 1450 and 1555–1620 cm −1 for all samples. Previous studies have assigned the band at 1450 cm −1 to C‐H vibration, and the other band presented in 1555–1610 cm −1 to polymerized hydrocarbons or aromatics . Obviously, these polymerized hydrocarbons are coke deposits, which gradually cover the active sites on the surface of the catalysts and lead to fast deactivation of VO x catalysts.…”

Section: Resultsmentioning

confidence: 99%

Structure and catalytic consequence of Mg‐modified VO_x/Al₂O₃catalysts for propane dehydrogenation

Liu

Zeng

et al. 2017

AIChE Journal

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Supported VOx catalysts are promising nonoxidative propane dehydrogenation (PDH) materials for their commercially attractive activity and propylene selectivity. However, they frequently suffer from rapid deactivation caused by coke deposition. This article describes the promoting role of magnesium on the stability of VOx/Al2O3 catalysts for PDH. A series of VOx/Al2O3 and Mg‐modified VOx/Al2O3 catalysts were synthesized by an incipient wetness impregnation method. The catalysts were carefully characterized by Raman spectra, UV‐Vis spectra, STEM, TGA and in situ DRIFTS. We showed that the stability of a 12V/Al2O3 catalyst was significantly improved on addition of small amounts of MgO. Experimental evidences indicate that V2O5 nanoparticles emerge in the 12V/Al2O3 samples, and appropriate Mg addition helps dispersing the V2O5 nanoparticles into 2D VOx species thus decreasing coke formation and improving stability in nonoxidative dehydrogenation of propane. © 2017 American Institute of Chemical Engineers AIChE J, 2017

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Infrared spectroscopic investigations relating to coke formation on zeolites I. Adsorption of hexene-1 and n-hexane on zeolites of type Y

Cited by 141 publications

References 12 publications

Interparticulate coke formation during hydrocarbon cracking on zeolite catalysts

Interparticulate coke formation during hydrocarbon cracking on zeolite catalysts

Reactions of the Conjugated Dienes Butadiene and Isoprene Alone and with Methanol Over Ion-Exchanged Montmorillonites

Structure and catalytic consequence of Mg‐modified VO_x/Al₂O₃catalysts for propane dehydrogenation

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Infrared spectroscopic investigations relating to coke formation on zeolites I. Adsorption of hexene-1 and n-hexane on zeolites of type Y

Cited by 141 publications

References 12 publications

Interparticulate coke formation during hydrocarbon cracking on zeolite catalysts

Interparticulate coke formation during hydrocarbon cracking on zeolite catalysts

Reactions of the Conjugated Dienes Butadiene and Isoprene Alone and with Methanol Over Ion-Exchanged Montmorillonites

Structure and catalytic consequence of Mg‐modified VOx/Al2O3catalysts for propane dehydrogenation

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Structure and catalytic consequence of Mg‐modified VO_x/Al₂O₃catalysts for propane dehydrogenation