A comprehensive study of product distributions and coke deposition during catalytic cracking of vacuum gas oil over hierarchical zeolites

Fals, Jayson; Toloza, Carlos A.T.; Puello-Polo, Esneyder; Márquez, Edgar; Méndez, Franklin J.

doi:10.1016/j.heliyon.2023.e15408

Cited by 4 publications

(2 citation statements)

References 43 publications

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“…With the increasing temperature of the thermal treatment from 800 • C to 860 • C, the signal at the wavenumber of 1550 cm −1 , associated with Brønsted acid sites, decreases and the LAS peak (at 1440 cm −1 ) increases, indicating the conversion of BAS to LAS. This can be explained again by a bleed-out of aluminum or iron atoms from the zeolite crystal lattice, removing the associated BAS and generating additional iron species outside the lattice structure, characterized by their Lewis acidic properties [31]. This hence confirms that the decrease in benzene selectivity is caused by a loss of BAS, the active sites for benzene formation, due to the insufficient thermal stability of the metal substituent in the zeolite lattice.…”

Section: Regeneration Using Comentioning

confidence: 62%

“…This result hence underscores the importance of a durable and resilient catalyst when employing CO 2 regeneration. lattice structure, characterized by their Lewis acidic properties [31]. This hence confi that the decrease in benzene selectivity is caused by a loss of BAS, the active sites for b zene formation, due to the insufficient thermal stability of the metal substituent in zeolite lattice.…”

Section: Regeneration Using Comentioning

confidence: 85%

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Coke Formation and Regeneration during Fe-ZSM-5-Catalyzed Methane Dehydro-Aromatization

Karpe,

Veser

2024

Catalysts

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Coke formation poses a significant obstacle in the direct conversion of methane into valuable chemicals such as ethylene, benzene, and hydrogen via methane dehydro-aromatization (MDA). At the elevated temperatures necessary for this reaction, coke is the thermodynamically favored product, causing rapid catalyst deactivation and hence necessitating frequent catalyst regeneration. Successful industrial implementation of MDA requires the advancement of catalyst regeneration processes and a comprehensive understanding of coke formation to enhance catalyst performance. Here, we examined the types of coke generated during MDA over a Fe-ZSM-5 catalyst and their impact on deactivation. By combining reactivity studies using catalysts with carefully controlled coke populations with the characterization of the catalyst via XRD, H2-TPR, and pyridine FTIR, we find that soft coke is formed at the Brønsted acid sites, resulting in loss of selectivity, while hard coke is formed at the metal sites causing a loss of activity. While soft coke can be removed at low regeneration temperatures, the removal of hard coke requires harsh conditions which compromise catalyst stability. An investigation into the use of CO2 as an alternative, mild oxidant for catalyst regeneration, however, shows that the mild oxidation strength of CO2 requires even higher regeneration temperatures and hence irreversible loss of Brønsted acid sites.

show abstract

Section: Regeneration Using Comentioning

confidence: 62%

Section: Regeneration Using Comentioning

confidence: 85%

Coke Formation and Regeneration during Fe-ZSM-5-Catalyzed Methane Dehydro-Aromatization

Karpe,

Veser

2024

Catalysts

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Deactivation and regeneration dynamics in hierarchical zeolites: Coke characterization and impact on catalytic cracking of vacuum gas oil

Fals,

Ospina-Castro,

Ramos-Hernández

et al. 2024

Heliyon

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Hierarchical Y Zeolite-Based Catalysts for VGO Cracking: Impact of Carbonaceous Species on Catalyst Acidity and Specific Surface Area

Fals,

Garcia-Valencia,

Puello-Polo

et al. 2024

Molecules

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The performance of catalysts prepared from hierarchical Y zeolites has been studied during the conversion of vacuum gas oil (VGO) into higher-value products. Two different catalysts have been studied: CatY.0.00 was obtained from the standard zeolite (Y-0.00-M: without alkaline treatment) and CatY.0.20 was prepared from the desilicated zeolite (Y-0-20-M: treated with 0.20 M NaOH). The cracking tests were carried out in a microactivity test (MAT) unit with a fixed-bed reactor at 550 °C in the 20–50 s reaction time range, with a catalyst mass of 3 g and a mass flow rate of VGO of 2.0 g/min. The products obtained were grouped according to their boiling point range in dry gas (DG), liquefied petroleum gas (LPG), naphtha, and coke. The results showed a greater conversion and selectivity to gasoline with the CatY.0.20 catalyst, along with improved quality (RON) of the C5–C12 cut. Conversely, the CatY.0.00 catalyst (obtained from the Y-0.00-M zeolite) showed greater selectivity to gases (DG and LPG), attributable to the electronic confinement effect within the microporous channels of the zeolite. The nature of coke has been studied using different analysis techniques and the impact on the catalysts by comparing the properties of the fresh and deactivated catalysts. The coke deposited on the catalyst surfaces was responsible for the loss of activity; however, the CatY.0.20 catalyst showed greater resistance to deactivation by coke, despite showing the highest selectivity. Given that the reaction occurs in the acid sites of the zeolite and not in the matrix, the increased degree of mesoporosity of the zeolite in the CatY.0.20 catalyst facilitated the outward diffusion of products from the zeolitic channels to the matrix, thereby preserving greater activity.

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A comprehensive study of product distributions and coke deposition during catalytic cracking of vacuum gas oil over hierarchical zeolites

Cited by 4 publications

References 43 publications

Coke Formation and Regeneration during Fe-ZSM-5-Catalyzed Methane Dehydro-Aromatization

Coke Formation and Regeneration during Fe-ZSM-5-Catalyzed Methane Dehydro-Aromatization

Deactivation and regeneration dynamics in hierarchical zeolites: Coke characterization and impact on catalytic cracking of vacuum gas oil

Hierarchical Y Zeolite-Based Catalysts for VGO Cracking: Impact of Carbonaceous Species on Catalyst Acidity and Specific Surface Area

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