Some observations on coke precursor on ZSM-5 during n-hexane cracking

Gielen, Bjorn; Palekar, M.G.

doi:10.1016/0144-2449(89)90028-6

Cited by 12 publications

(3 citation statements)

References 29 publications

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“…In the recent years, considerable efforts have been made to arrive at a possibly full understanding of the factors responsible for the formation of coke in the intracrystalline channels or on the external surfaces of microporous molecular sieves. − Despite the vast amount of data accumulated during the last two decades, many questions still remain open or controversial. Investigations carried out up to now have mainly focused on zeolites, including the most commonly used ZSM-5. − The wide-porous zeolites, like mordenite or zeolite Y, have been studied relatively infrequently and mostly for comparative purposes. − Carbonaceous deposits formed during the conversion of methanol over zeolite Y have been studied with different techniques such as thermogravimetric analysis (TGA); , gas chromatography (GC); coke combustion combined with GC; , and spectroscopic methods including UV−vis, , IR, − ESR, and 1 H, 13 C, 27 Al, and 29 Si NMR. , It has been concluded that the temperature of the reaction and the pore structure of the zeolite have essential effects on the nature and amount of carbonaceous deposits formed in a particular system . As has been found, three different types of the deposits can be distinguished depending on the reaction temperature.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Coke Deposits on Al-MCM-41

et al. 2001

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Carbonaceous compounds deposited on aluminosilicate mesoporous molecular sieves of the MCM-41 type during conversion of cyclohexene at various temperatures were investigated using TGA; DRIFT, UV-vis, and 13 C solid state NMR spectroscopies; and a sorption technique. The chemical composition of the deposits is not significantly affected by the Al content of Al-MCM-41 and depends mainly on the temperature and the duration of the reaction. At lower applied temperatures, both aliphatic and aromatic compounds are formed; they are relatively weakly bound to the surface of the material. After a longer reaction period, some deposits appear that are strongly bound to the surface. At higher temperatures, a fraction of the coke migrates out of the pores. Then, part of the coke (most likely aliphatics) desorbs and moves away, while the other part (presumably aromatics) adsorbs on the external surface of the sieve. The coke remaining both in the pores and on the external surface mostly forms multilayered polyaromatic structures that are strongly bound to the surface of the material. The water sorption capacity of the studied materials decreases with the content of the deposits.

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Section: Introductionmentioning

confidence: 99%

Investigation of Coke Deposits on Al-MCM-41

et al. 2001

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“…During the upgrading reactions, the activity of upgrading catalysis (especially cracking catalysis) rapidly decreases. 13 To reduce coke deposition, it is very beneficial to understand the mechanism of coke formation during the reaction and its effects on the catalyst performance. A major step for coke deposition is the formation of coke precursors, such as olefins and diolefins.…”

Section: Characterization Of Produced Gases Duringmentioning

confidence: 99%

“…Coke formation and catalyst deactivation are one of the most important technological and economic problems in upgrading processes of the petrochemical industry. During the upgrading reactions, activity of the upgrading catalysis (especially cracking catalysis) rapidly decreases . To reduce coke deposition, it is very beneficial to understand the mechanism of coke formation during the reaction and its effects on the catalyst performance.…”

Section: Introductionmentioning

confidence: 99%

In Situ Upgrading of Athabasca Bitumen Using Multimetallic Ultradispersed Nanocatalysts in an Oil Sands Packed-Bed Column: Part 2. Solid Analysis and Gaseous Product Distribution

2014

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Thermal cracking of Athabasca bitumen was carried out in an oilsand packed-bed column, in the presence and absence of in situ prepared trimetallic nanocatalysts at a pressure of 3.5 MPa, residence time of 36 h, and temperatures of 320 and 340°C. In this part of the study, the effects of reaction severity (time and temperature) as well as the presence of nanocatalysts in packed media on solid and gaseous products were investigated. Results showed that the presence of trimetallic nanocatalysts enhanced the hydrogenation reactions and, consequently, led to significant reduction of coke formation (51.3%) and CO 2 emission reduction. Further, the analysis of the gaseous products and deposited solids confirmed the previous findings reported in part 1 (10.1021/ef401716h) of this study. The accumulative volume of coke precursor gases, such as ethylene and propylene, increased with the reaction severity. However, reaction severity has no significant effect on the atomic metallic ratios (metal/total metal) of the employed trimetallic nanocatalysts, which clearly demonstrates the stability of injected ultradispersed (UD) nanocatalysts (metal/total metal: Mo, 0.6267; Ni, 0.1808; and W, 0.1924) in the porous media at high pressure and temperature. Nonetheless, aggregation of nanocatalysts inside the porous media was observed and graphically demonstrated by environmental scanning electron microscopy (ESEM) images. Overall, the presence of trimetallic nanocatalysts in porous media not just enhanced bitumen upgrading but also improved the produced liquid quality and reduced the coke content as well as CO 2 emission by 50%.

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Vapor phase alkylation of aniline using ethanol over alkali and alkaline-earth exchanged zeolites-Y

Yuvaraj

Palanichamy

1996

React Kinet Catal Lett

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Some observations on coke precursor on ZSM-5 during n-hexane cracking

Cited by 12 publications

References 29 publications

Investigation of Coke Deposits on Al-MCM-41

Investigation of Coke Deposits on Al-MCM-41

In Situ Upgrading of Athabasca Bitumen Using Multimetallic Ultradispersed Nanocatalysts in an Oil Sands Packed-Bed Column: Part 2. Solid Analysis and Gaseous Product Distribution

Vapor phase alkylation of aniline using ethanol over alkali and alkaline-earth exchanged zeolites-Y

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