Catalytic cracking of alkanes on FAU: Single‐event microkinetic modeling including acidity descriptors

Borm, Rhona Van; Reyniers, Marie-Françoise; Marin, Guy

doi:10.1002/aic.13831

Cited by 18 publications

(21 citation statements)

References 72 publications

(125 reference statements)

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“…This descriptor has a clear relation to the acid strength distribution of the zeolite as the stabilization of these carbenium species occurs at the acid sites within the zeolite [60]. This approach has been widely utillized to explain the effects of acid strength distribution within one specific type of zeolite for cracking reactions [61][62][63][64] and to model the effect of different Si/Al ratios within a single zeolite [65][66][67], as the Si/Al ratio can be related to a change in average acid strength.…”

Section: Experimental Effect Of Si/al Ratiomentioning

confidence: 99%

Study of n-butanol conversion to butenes: Effect of Si/Al ratio on activity, selectivity and kinetics

Gunst

Sabbe

Reyniers

et al. 2019

Applied Catalysis A: General

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As bio-butanol is gaining more and more interest as a commercially available bioresource, the dehydration of this alcohol towards butenes and higher carbons gains more of interest. In general HZSM-5 has shown to be the most promising catalyst for this conversion. The role of the zeolite's Si/Al ratio in the butanol dehydration reaction is still not fully understood. Experimental data obtained for a series of HZSM-5 with decreasing Si/Al ratio revealed an increase in activity of the catalyst per active site without affecting the selectivity profile. To understand the underlying effects, a microkinetic model was constructed for H-ZSM-5 with a Si/Al ratio of 25, based on literature DFT calculations, and the model was further modified by fitting the key parameters to the measured data at the four different temperatures studied in this work. This resulted in an adequate model for the dehydration of butanol across the evaluated temperature range of 503K to 533K. Investigation of the occurring mechanisms indicated a inhibiting effect due to the strong adsorption of din -butylether. This 'poisoning' of the catalyst surface resulted in a peculiar S-like curve for the conversion site time relation, which was also experimentally observed. This newly fitted base model was used to obtain more insight in the effect of the Si/Al ratio by implementing an additional H parameter, which is related to the adsorption strength of n-butanol in the base model. H varies between-4.8 to +11.3 kJ/mol and provides a good fit for Si/Al ratios ranging from 15 to 140. The higher dehydration rates observed with decreasing Si/Al can be traced back to an increase in adsorption strength resulting in an overall increase in surface coverage. The constant selectivity-conversion profile can be explained by a similar dependency of all elementary steps on the adsorption strength. The model developed in this study enables to simulate and understand the experimentally observed effects of temperature and Si/Al ratio on the n-butanol dehydration.

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Section: Experimental Effect Of Si/al Ratiomentioning

confidence: 99%

Study of n-butanol conversion to butenes: Effect of Si/Al ratio on activity, selectivity and kinetics

Gunst

Sabbe

Reyniers

et al. 2019

Applied Catalysis A: General

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“…Now with the calculated value for the intrinsic activation energy and Eq. (22), it is possible to calculate the adsorption enthalpy for the type 2 cracking sites, being this value -147.7 kJ mol -1 , that indicates a stronger adsorption of n-heptane on sites type 2 than on sites type 1.…”

Section: Isosteric Heat Of Adsorption (Q St )mentioning

confidence: 99%

Catalytic cracking of n-alkane naphtha: The impact of olefin addition and active sites differentiation

Corma

Cuquerella

Miguel

2015

Journal of Catalysis

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An extended dual kinetic model allows to fit the n-heptane cracking results working in a wide range of reaction conditions. The duality of the model is provided by the contribution of monomolecular and bimolecular cracking mechanisms. It takes into account the role played by the olefins formed on the global cracking or added within the feed. Furthermore by means of this model and the kinetic parameters obtained when cracking n-heptane on ZSM-5, it has been observed that, while some characterization techniques show a homogeneous zeolite surface from the point of view of the active sites, rigorous kinetic experiments point to the possibility that the reactant sees a heterogeneous surface with, at least, two group of cracking active sites. Those differentiated active sites give different cracking rates and different activation energies for the process and, in the case of ZSM-5, could be assimilated to sites pointing to the 10R channels and sites pointing into the crossing of the 10R channels, mainly due to differences in acid site location and confinement effects.3

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“…The cracking performances of the SL-CGO conducted over four different cracking materials are shown in Table . There can be little doubt that the feed conversions and product yields are obviously distinct on different cracking materials because the HYZ is the main component that promotes the hydrocarbon catalytic cracking . To the best of our knowledge, there are two mechanisms that can explain the harmful effect of the nitrogen compounds over cracking catalysts.…”

Section: Resultsmentioning

confidence: 99%

Structure and Composition Changes of Nitrogen Compounds during the Catalytic Cracking Process and Their Deactivating Effect on Catalysts

Chen

Liu

et al. 2017

Energy Fuels

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The comprehensive structure and composition changes of the nitrogen compounds during the catalytic cracking processes of coker gas oil and vacuum residue are investigated using electrospray ionization combined with Fourier transform ion cyclotron resonance mass spectrometry. These experiments were conducted over different cracking materials under the reaction temperatures of 500/520 °C, the weight hourly space velocity of 18 h–1, and the catalyst/oil ratio of 5. The results show that the diffusion resistance in the micropores of the zeolite is the key factor affecting the interaction between the nitrogen compounds and the acid sites. The basic N1 and N2 class species with double bond equivalence (DBE) values smaller than 10 can easily diffuse into the micropores of the zeolite and are preferentially adsorbed onto the acid sites. These adsorbed nitrogen compounds generally conduct condensation reactions and hydrogen transfer reactions to form coke deposited on the cracking catalysts. The basic N1 and N2 class species with DBE values larger than 10, other basic nitrogen compounds other than N1 and N2, and the non-basic nitrogen compounds seldom interact with the acid sites of the zeolite. They usually undergo side chain thermal cracking on the surface of the matrix, which can reduce their carbon numbers but cannot change their DBE values. The basic N1 class species with DBE values smaller than 10 are the main compounds that poison the cracking catalysts. In comparison to the SL-CGO catalytic cracking, the nitrogen-poisoning effect on the catalysts is much less during the SL-VR catalytic cracking process because the main poisoning compounds (the basic N1 class species with DBE values smaller than 10) are much fewer.

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Catalytic cracking of alkanes on FAU: Single‐event microkinetic modeling including acidity descriptors

Cited by 18 publications

References 72 publications

Study of n-butanol conversion to butenes: Effect of Si/Al ratio on activity, selectivity and kinetics

Study of n-butanol conversion to butenes: Effect of Si/Al ratio on activity, selectivity and kinetics

Catalytic cracking of n-alkane naphtha: The impact of olefin addition and active sites differentiation

Structure and Composition Changes of Nitrogen Compounds during the Catalytic Cracking Process and Their Deactivating Effect on Catalysts

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