Hydride Transfer versus Deprotonation Kinetics in the Isobutane–Propene Alkylation Reaction: A Computational Study

Liu, C Chong; Santen, Rutger A. van; Poursaeidesfahani, Ali; Vlugt, Tjh Thijs; Pidko, Evgeny A.; Hensen, Emiel J. M.

doi:10.1021/acscatal.7b02877

Cited by 51 publications

(54 citation statements)

References 81 publications

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“…While the formation of higher olefins can be attributed to the oligomerization of ethylene catalysed by BAS, formation of paraffins and aromatics (including coke) is related to dehydrogenation and hydrogen transfer processes. 40,41 The low yield of saturated hydrocarbons indicates that the main pathway to form aromatics is dehydrogenation. Dehydrogenation can be catalysed by both BAS and Lewis acidic sites.…”

Section: Influence Of Metal Promotion On Ethylene Aromatizationmentioning

confidence: 99%

Aromatization of ethylene over zeolite-based catalysts

Uslamin

Saito

Kosinov

et al. 2020

Catal. Sci. Technol.

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Section: Influence Of Metal Promotion On Ethylene Aromatizationmentioning

confidence: 99%

Aromatization of ethylene over zeolite-based catalysts

Uslamin

Saito

Kosinov

et al. 2020

Catal. Sci. Technol.

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“…Li-LSX zeolite contains a low Si/Al ratio (1.0), large surface area and pores size between 7 and 12 Å. The addition of a metal to large pores Faujalite zeolites was linked to enhanced hydrocracking and alkylation activity by providing a large surface area and interactions between Lewis and Bronsted acid sites [23]. Deoxygenation occurred mostly via dehydration and decarbonylation as shown by the gas analysis.…”

Section: Pyrolysis Mechanismmentioning

confidence: 98%

Stability of Li-LSX Zeolite in the Catalytic Pyrolysis of Non-Treated and Acid Pre-Treated Isochrysis sp. Microalgae

2020

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This paper investigates the use of Li-LSX-zeolite catalyst over three regeneration cycles in presence of non-treated and acid pre-treated Isochrysis sp. microalgae. The spent and regenerated catalysts were characterised by surface analysis, elemental analysis (EA), SEM-EDS, and XRD to correlate their properties with the bio-oil yield and quality. The acid pre-treatment removed alkali metals, reducing gas yield in favour of bio-oil, but, at the same time, led to catalyst deactivation by fouling. Differently, the non-treated microalgae resulted in a bio-oil enriched in C and H and depleted in O, compared to the pre-treated ones, denoting higher deoxygenation activity. After 3 pyrolysis/regeneration cycles, the analyses suggest that there are no major changes on catalyst using non-treated microalgae. Regeneration at 700 °C has been shown to be able to remove most of the coke without damaging the Li-LSX zeolite structure. In summary, Li-LSX zeolite was effective in maintaining deoxygenation activity over three cycles in the pyrolysis of non-treated Isochrysis microalgae, while the algae pre-treatment with sulphuric acid was detrimental on the catalyst activity.

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“…First-principles microkinetics simulations based on quantum chemically calculated elementary reaction rate data representative for these two cases are available. 26 In these simulations, faujasite zeolites with reactive and less reactive protons were compared. The default reaction rate parameters selected in the kinetics simulations of this paper have been chosen to give approximate agreement with the data of the microkinetics simulations.…”

Section: Deactivation Kinetics Of the Alkylation Reactionmentioning

confidence: 99%

“… 19 , 31 Therefore, competition between hydride transfer and oligomerization reactions is in favor of the hydride transfer reaction when it is catalyzed by highly reactive proton sites. 10 , 26 …”

Section: Introductionmentioning

confidence: 99%

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Deactivation Kinetics of Solid Acid Catalyst with Laterally Interacting Protons

et al. 2018

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Differences in catalyst deactivation kinetics in solid acid catalysis are studied with catalyst models that allow for lateral interaction between protons. Deactivation of a solid acid catalyst with laterally interacting protons induces inhomogeneity of proton reactivity that develops with time. As a consequence, product selectivity changes and deactivation will accelerate. This is demonstrated by simulations of the deactivation kinetics of the alkylation reaction of propylene with isobutane. The effect of lateral interactions between protons arises because initial catalyst deactivation is not caused by pore blocking or coke deposition but by a molecular mechanism where protons are consumed due to the formation of stable nonreactive carbenium ions. High selectivity to alkylate requires a catalyst with protons of high reactivity. When protons become consumed by formation of stable deactivating carbenium ions, initially reactive protons are converted into protons of lower reactivity. The latter only catalyze deactivating oligomerization reactions. Simulations that compare the deactivation kinetics of a catalyst model with laterally interacting protons and a catalyst model that contains protons of similar but different reactivity, but that do not laterally interact, are compared. These simulations demonstrate that the lateral interaction catalyst model is initially more selective but also has a lower stability. Catalyst deactivation of the alkylation reaction occurs through two reaction channels. One reaction channel is due to oligomerization of reactant propylene. The other deactivation reaction channel is initiated by deprotonation of intermediate carbenium ions that increase alkene concentration. By consecutive reactions, this also leads to deactivation. The hydride transfer reaction competes with oligomerization reactions. It is favored by strongly acid sites that also suppress the deprotonation reaction. Within the laterally interacting proton catalyst model, when reactive protons become deactivated, weakly reactive protons are generated that only catalyze the deactivating alkene oligomerization and consecutive reactions. This rapid formation of the weakly reactive protons is the cause of decreasing selectivity with reaction time and increased rate of deactivation. Solutions of the mean field kinetic equations as well as stochastic simulations are presented. Comparative simulations with a reduced number of neighbors of the protons illustrate decreased deactivation rates when the proton density decreases. Island formation of adsorbed reaction intermediates on the catalyst surface is observed in stochastic kinetics simulations. When alkylation selectivity is high, this island formation increases the rate of catalyst deactivation in comparison to the rate of deactivation according to the mean field studies. A nonlinear dynamics model of proton dynamics is provided, which shows that the differences between stochastic and mean field simulations are due to frustrated proton state percolation.

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Hydride Transfer versus Deprotonation Kinetics in the Isobutane–Propene Alkylation Reaction: A Computational Study

Cited by 51 publications

References 81 publications

Aromatization of ethylene over zeolite-based catalysts

Aromatization of ethylene over zeolite-based catalysts

Stability of Li-LSX Zeolite in the Catalytic Pyrolysis of Non-Treated and Acid Pre-Treated Isochrysis sp. Microalgae

Deactivation Kinetics of Solid Acid Catalyst with Laterally Interacting Protons

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