Hydrocracking of n-butane and n-heptane over a sulfided nickel erionite catalyst

Heck, R. H.; Chen, N.Y.

doi:10.1016/0926-860x(92)85140-7

Cited by 9 publications

(5 citation statements)

References 25 publications

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“…This light-naphtha reforming process selectively hydrocracks short-chain n-pentane and n-hexane, removing them from the gasoline pool to yield liquid petroleum gas (LPG). The overall effect on the gasoline pool is one of reduced volatility and increased octane number [3][4][5]. The resulting high-octane gasoline is compatible with high-compression engines and their concomitant advantage of increased mileage.…”

Section: Introductionmentioning

confidence: 99%

Understanding cage effects in the n-alkane conversion on zeolites

Maesen

Beerdsen

Calero

et al. 2006

Journal of Catalysis

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Molecular simulations are used to provide insight into published catalytic reactivity data for zeolites that exhibit a cage effect, the selective and preferential conversion of short-chain rather than long-chain n-alkanes. This paper demonstrates that understanding cage effects for ERI-, AFX-, and FER-type zeolites requires consideration of four components: (1) adsorption thermodynamics, (2) adsorption kinetics, (3) conversion at the exterior surface of the catalysts, and (4) coke-induced modifications to the pore texture. By breaking down the Gibbs free energy of adsorption into its enthalpic and entropic contributions, we can further elucidate the influence of the zeolite topology on the adsorption of n-alkanes with different hydrocarbon chain lengths. This analysis indicates that zeolite topologies with cages accessible through windows <0.47 nm wide are particularly prone to exhibiting a cage effect, because they impose a high thermodynamic penalty on the adsorption of molecules that are too long to fit comfortably in a single cage. This improved understanding of the cage effect could facilitate its renewed use in commercial practice.  2005 Elsevier Inc. All rights reserved.

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Section: Introductionmentioning

confidence: 99%

Understanding cage effects in the n-alkane conversion on zeolites

Maesen

Beerdsen

Calero

et al. 2006

Journal of Catalysis

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“…The formation of lighter alkanes can also be achieved by hydride transfer from alkanes in the gas phase (i.e., n -butane under differential conditions) to the surface alkoxy groups (eq ). ,,− Under differential conditions, it can be assumed that the active sites are composed of BAS and butoxy groups, as is shown in eq . At low temperatures, when n -butane dehydrogenation is thermodynamically disfavored, θ H + Z – ≈ 1. Additionally, site balance at steady-state gives .…”

Section: Results and Discussionmentioning

confidence: 99%

“…At a moderate temperature of 683 K when the active sites in zeolite are predominantly H + Z – , the primary cracking reactions toward ethane and methane are close to first order in butane (Figure a) and zeroth order in H 2 (Figure d), which differ from the bimolecular reaction routes for C 3 and C 5 hydrocarbons at the same conditions. The insensitivity to p H 2 indicates that the cracking reactions toward methane and ethane (eq ) likely proceed through the direct conversion of n -butane without forming n -butenes following the Haag–Dessau mechanism. It has also been widely accepted that the rate-determining step of monomolecular cracking is the activation/protonation of the molecular alkane on the BAS to form a carbonium transition state. ,,,, When θ H + Z – ≈ 1, the reaction rate of eq can be approximated as which is first order in p n ‑C 4 H 10 and zeroth order in p H 2 , principally matching the reaction orders derived from methane and ethane formation at 683 K. Therefore, it is evident that the primary cracking reactions toward methane and ethane are predominantly monomolecular at mild conditions. As reaction temperature increased, the apparent reaction orders in the primary cracking from n -butane to methane remained about one and zero concerning n -C 4 H 10 and H 2 , respectively.…”

Section: Results and Discussionmentioning

confidence: 99%

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Cracking of Butane on a Pt/H-ZSM-5 Catalyst in the Presence of Hydrogen

Shou

Dasari

Broekhuis

et al. 2022

Ind. Eng. Chem. Res.

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This work provides a detailed interpretation of the complex reaction mechanisms of n-butane on Pt/H-ZSM-5 catalyst in the presence of H 2 from the perspective of kinetics. In one route, n-butane conversion involved dehydrogenation on Pt to form butene and isomerization, dimerization, and cracking steps on the acid sites in the zeolite. Alternatively, butane could have underwent direct protolytic cracking on zeolite. On zeolite surfaces dominated by unoccupied Brønsted acid sites, protolytic cracking of butane was the preferred primary cracking mechanism. As the coverage of C 4 surface adsorbate increased, the routes via butene became prominent and likely dominated under practical conditions with high hydrocarbon partial pressures. The various reaction pathways all followed the Langmuir−Hinshelwood rate model. With over 90% combined selectivity of propane and ethane at nearly full butane conversion and good catalyst regenerability, this mechanism presents an effective way to convert butane fuel to chemical feedstocks.

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“…457 There was some evidence for the involvement of reactants in a set of reactions such as OLI, deHYD/HYD, hydrogen transfer and cracking. The study by Heck and Chen highlighted the importance of alkene partial pressure over the catalyst.…”

Section: Bifunctional Zeolitic Silica-alumina Hcr Catalystsmentioning

confidence: 98%

Catalysis in the Upgrading of Fischer–Tropsch Syncrude

2010

Catalysis in the Refining of Fischer-Tropsch Syncrude

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The catalysis of conversion technologies that are found in most commercial Fischer–Tropsch upgrading and refining facilities are discussed. Four main classes of catalysis are considered, namely a) alkene oligomerisation, b) isomerisation and hydroisomerisation of alkanes and alkenes, c) cracking and hydrocracking, and d) hydrotreating. The focus is on catalysis, with aspects such as oxygenates, oxygenate related deactivation, commercial processes and Fischer–Tropsch application specifics being highlighted.

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Hydrocracking of n-butane and n-heptane over a sulfided nickel erionite catalyst

Cited by 9 publications

References 25 publications

Understanding cage effects in the n-alkane conversion on zeolites

Understanding cage effects in the n-alkane conversion on zeolites

Cracking of Butane on a Pt/H-ZSM-5 Catalyst in the Presence of Hydrogen

Catalysis in the Upgrading of Fischer–Tropsch Syncrude

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