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Catalysts
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Kinetics and Mechanism of Catalytic Reactions—Integrity of Experiment and Theory
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Kinetics and Mechanism of Catalytic Reactions—Integrity of Experiment and Theory

A special issue of Catalysts (ISSN 2073-4344). This special issue belongs to the section "Environmental Catalysis".

Deadline for manuscript submissions: closed (28 February 2022) | Viewed by 19916

Special Issue Editor

Prof. Dr. Anton Naydenov

E-Mail Website
Guest Editor
Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Sofia, Bulgaria
Interests: environmental catalysis; reaction kinetics; mechanistic models of catalytic reactions; experimental investigation and mathematical modeling of different types of catalytic reactors; development of computation procedures for identifying the kinetics and mechanisms of catalytic reactions
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Kinetics and Mechanism of Catalytic Reactions—Integrity of Experiment and Theory

Catalytic reactions play a key role in sustainable chemical industry, in energy generation, and in environmental protection. Detailed understanding of the kinetics and insight into the mechanism of catalytic reactions is critical for reliable reactor modeling and, therefore, for further practical implementation of catalytic processes. On one side, evaluation of catalysts requires a deep knowledge of phenomena such as adsorption, desorption, and elementary steps in surface interactions. In parallel, the influence of the factors defining thermal stability and resistance to catalytic poisons is also of great importance. Studies on reaction kinetics and mechanisms are very complex and include the application of advanced experimental systems for catalytic testing and catalyst characterization, together with the development of computational skills to account for the effects of internal and external mass and heat transfer within catalysts, laboratory and pilot-scale reactors, etc.

This Special Issue is devoted to the current progress and the perspective tendencies of scientific research in mechanisms and kinetics of catalytic reactions with a main focus on new techniques for advanced experimental studies and their integrity with the trends in the theory of catalysis.

Prof. Dr. Anton Naydenov
Guest Editor

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Keywords

  • catalytic reaction
  • reaction mechanism
  • reaction kinetics
  • kinetic equation
  • catalytic test
  • catalytic reactor
  • laboratory reactor
  • mechanistic model
  • reactor modeling
  • fixed bed reactor
  • monolithic reactor
  • deactivation model

Published Papers (9 papers)

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Research

14 pages, 3608 KiB  
Article
Catalytic Effect of CO2 and H2O Molecules on •CH3 + 3O2 Reaction
by Mohamad Akbar Ali, Manas Ranjan Dash and Latifah Mohammed Al Maieli
Catalysts 2022, 12(7), 699; https://doi.org/10.3390/catal12070699 - 25 Jun 2022
Cited by 3 | Viewed by 1547
Abstract
The methyl (•CH3) + 3O2 radical is an important reaction in both atmospheric and combustion processes. We investigated potential energy surfaces for the effect of CO2 and H2O molecules on a •CH3 [...] Read more.
The methyl (•CH3) + 3O2 radical is an important reaction in both atmospheric and combustion processes. We investigated potential energy surfaces for the effect of CO2 and H2O molecules on a •CH3+ O2 system. The mechanism for three reaction systems, i.e., for •CH3 + 3O2, •CH3 + 3O2 (+CO2) and •CH3 + 3O2 (+H2O), were explored using ab initio/DFT methods [CCSD(T)//M062X/6-311++G(3df,3pd)] in combination with a Rice−Ramsperger−Kassel−Marcus (RRKM)/master-equation (ME) simulation between a temperature range of 500 to 1500 K and a pressure range of 0.0001 to 10 atm. When a CO2 and H2O molecule is introduced in a •CH3 + 3O2 reaction, the reactive complexes, intermediates, transition states and post complexes become thermodynamically more favorable. The calculated rate constant for the •CH3 + 3O2 (3 × 10−15 cm3 molecule−1 s−1 at 1000 K) is in good agreement with the previously reported experimentally measured values (~1 × 10−15 cm3 molecule−1 s−1 at 1000 K). The rate constant for the effect of CO2 (3 × 10−16 cm3 molecule−1 s−1 at 1000 K) and H2O (2 × 10−17 cm3 molecule−1 s−1 at 1000 K) is at least one–two-order magnitude smaller than the free reaction (3 × 10−15 cm3 molecule−1 s−1 at 1000 K). The effect of CO2 and H2O on •CH3 + 3O2 shows non-RRKM behavior, however, the effect on •CH3 + 3O2 shows RRKM behavior. Our results also demonstrate that a single CO2 and H2O molecule has the potential to accelerate a gas-phase reaction at temperature higher than >1300 K and slow the reaction at a lower temperature. The result is unique and observed for the first time. Full article
(This article belongs to the Special Issue Kinetics and Mechanism of Catalytic Reactions—Integrity of Experiment and Theory)
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19 pages, 3961 KiB  
Article
Reaction Kinetics and Mechanism of VOCs Combustion on Mn-Ce-SBA-15
by Anton Naydenov, Ralitsa Velinova, Jean-Luc Blin, Laure Michelin, Bénédicte Lebeau, Hristo Kolev, Yordanka Karakirova, Daniela Karashanova, Loïc Vidal, Anna Dotzeva, Krasimir Tenchev and Silviya Todorova
Catalysts 2022, 12(6), 583; https://doi.org/10.3390/catal12060583 - 26 May 2022
Cited by 3 | Viewed by 1806
Abstract
A propane combustion catalyst based on Mn and Ce and supported by SBA-15 was prepared by the “two-solvents” method aiming at the possible application in catalytic converters for abatement of alkanes in waste (exhaust) gases. The catalyst characterization was carried out by SAXS, [...] Read more.
A propane combustion catalyst based on Mn and Ce and supported by SBA-15 was prepared by the “two-solvents” method aiming at the possible application in catalytic converters for abatement of alkanes in waste (exhaust) gases. The catalyst characterization was carried out by SAXS, N2-physisorption, XRD, TEM, XPS, EPR and H2-TPR methods. The catalysts’ performance was evaluated by tests on the combustion of methane, propane and butane. The reaction kinetics investigation showed that the reaction orders towards propane and oxygen were 0.7 and 0.1, respectively. The negative reaction order towards the water (−0.3) shows an inhibiting effect on the water molecules. Based on the data from the instrumental methods, catalytic experiments and mathematic modeling of the reaction kinetics, one may conclude that the Mars–van Krevelen type of mechanism is the most probable for the reaction of complete propane oxidation over single Mn and bi-component Mn-Ce catalysts. The fine dispersion of manganese and cerium oxide and their strong interaction inside the channels of the SBA-15 molecular sieve leads to the formation of difficult to reduce oxide phases and consequently, to lower catalytic activity compared to the mono-component manganese oxide catalyst. It was confirmed that the meso-structure was not modified during the catalytic reaction, thus it can prevent the agglomeration of the oxide particles. Full article
(This article belongs to the Special Issue Kinetics and Mechanism of Catalytic Reactions—Integrity of Experiment and Theory)
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23 pages, 6031 KiB  
Article
Kinetics of Catalytic Decarboxylation of Naphthenic Acids over HZSM-5 Zeolite Catalyst
by Nihad Omer Hassan, Mohamed Challiwala, Dhallia Mamoun Beshir and Nimir O. Elbashir
Catalysts 2022, 12(5), 495; https://doi.org/10.3390/catal12050495 - 28 Apr 2022
Cited by 1 | Viewed by 2014
Abstract
Naphthenic acids are naturally occurring carboxylic acids in crude oil with cyclic or aromatic rings in their structure. These carboxylic acids are responsible for the acidity of crude oil, leading to corrosion problems in refinery equipment and the deactivation of catalysts while creating [...] Read more.
Naphthenic acids are naturally occurring carboxylic acids in crude oil with cyclic or aromatic rings in their structure. These carboxylic acids are responsible for the acidity of crude oil, leading to corrosion problems in refinery equipment and the deactivation of catalysts while creating a continuous need for maintenance. Therefore, removing naphthenic acids has become an important requirement in refining acidic crude oil. In this paper, experiments are conducted to investigate the use of HZSM-5 zeolite catalyst to reduce the total acid number (TAN) of a typical acidic crude oil obtained from Al-Fula blocks in Western Sudan. TAN is an important metric signifying the acidity of crude oil. A full factorial design of the experiment (DOE) framework enabled a better understanding of the efficacy of the catalyst at three parametric levels (reaction temperature: 250-270-300 °C, reaction time: 2-3-4 h, and oil:catalyst weight ratio: 20-22-25 g/g). The results demonstrate that the HZSM-5 zeolite catalyst provides up to 99% removal of naphthenic acids via the decarboxylation route. Additionally, the removal efficiency increases with increasing temperature and residence time. The acidity of the crude oil was shown to decrease after treatment with the catalyst for four hrs.; from 6.5 mg KOH/g crude to 1.24; 0.39 and 0.17 mg KOH/g at 250; 270 and 300 °C, respectively. A sharp decrease of TAN was observed at the oil catalyst mass ratio of 20 g/g at 250 °C, and almost complete conversion of acids was achieved after 4 hrs. Another experiment at 270 °C showed a converse relationship between the oil:catalyst ratio and acid removal; suggesting the activation of side reactions at higher temperature conditions catalyzed by excess acid. Finally; a Langmuir–Hinshelwood (LH) kinetic model has been developed to enable rapid prediction of the performance of the HZSM-5 zeolite catalyst for decarboxylation reaction. The model has also been validated and tested in ASPEN® software for future simulation and scalability studies. Full article
(This article belongs to the Special Issue Kinetics and Mechanism of Catalytic Reactions—Integrity of Experiment and Theory)
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14 pages, 24719 KiB  
Article
DFT Study on the Combined Catalytic Removal of N2O, NO, and NO2 over Binuclear Cu-ZSM-5
by Congru Gao, Jianwei Li, Jie Zhang and Xiuliang Sun
Catalysts 2022, 12(4), 438; https://doi.org/10.3390/catal12040438 - 13 Apr 2022
Cited by 2 | Viewed by 2289
Abstract
The large amount of nitrogen oxides (N2O, NO, NO2, etc.) contained in the flue gas of industrial adipic acid production will seriously damage the environment. A designed binuclear Cu-ZSM-5 catalyst can be applied to decompose N2O and [...] Read more.
The large amount of nitrogen oxides (N2O, NO, NO2, etc.) contained in the flue gas of industrial adipic acid production will seriously damage the environment. A designed binuclear Cu-ZSM-5 catalyst can be applied to decompose N2O and reduce NO and NO2, purifying the air environment. Using the density functional theory method, the catalytic decomposition mechanisms of N2O, NOX-NH3-SCR, and NOX-assisted N2O decomposition is simulated over the Cu-ZSM-5 model. The results indicate that N2O can be catalytically decomposed over the binuclear Cu active site in the sinusoidal channel. The speed-limiting step is the second N2O molecule activation process. After the decomposition of the first N2O molecule, a stable extra-frame [Cu-O-Cu]2+ structure will generate. The subsequent discussion proved that the NOX-NH3-SCR reaction can be realized over the [Cu-O-Cu]2+ active site. In addition, it proved that the decomposition reaction of NO and NO2 can be carried out over the [Cu-O-Cu]2+ active site, and NO can greatly reduce the energy barrier for the conversion of the active site from [Cu-O-Cu]2+ to the binuclear Cu form, while NO2 can be slightly reduced. Through discussion, it is found that the binuclear Cu-ZSM-5 can realize the combined removal of N2O and NOX from adipic acid flue gas, hoping to provide a theoretical basis for the development of a dual-functional catalyst. Full article
(This article belongs to the Special Issue Kinetics and Mechanism of Catalytic Reactions—Integrity of Experiment and Theory)
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15 pages, 5969 KiB  
Article
Magnesium-Modified Co3O4 Catalyst with Remarkable Performance for Toluene Low Temperature Deep Oxidation
by Abraham Atour Zigla, Tim Kox, Daniel Mevoa, Hypolite Todou Assaouka, Issah Njiawouo Nsangou, Daniel Manhouli Daawe, Stephane Kenmoe and Patrick Mountapmbeme Kouotou
Catalysts 2022, 12(4), 411; https://doi.org/10.3390/catal12040411 - 07 Apr 2022
Cited by 15 | Viewed by 2224
Abstract
Co3O4, MgCo2O4 and MgO materials have been synthesized using a simple co-precipitation approach and systematically characterized. The total conversion of toluene to CO2 and H2O over spinel MgCo2O4 with wormlike [...] Read more.
Co3O4, MgCo2O4 and MgO materials have been synthesized using a simple co-precipitation approach and systematically characterized. The total conversion of toluene to CO2 and H2O over spinel MgCo2O4 with wormlike morphology has been investigated. Compared with single metal oxides (Co3O4 and MgO), MgCo2O4 with the highest activity has exhibited almost 100% oxidation of toluene at 255 °C. The obtained results are analogous to typical precious metal supported catalysts. The activation energy of toluene over MgCo2O4 (38.5 kJ/mol) is found to be much lower than that of Co3O4 (68.9 kJ/mol) and MgO ((87.8 kJ/mol)). Compared with the single Co and Mg metal oxide, the as-prepared spinel MgCo2O4 exhibits a larger surface area, highest absorbed oxygen and more oxygen vacancies, thus highest mobility of oxygen species due to its good redox capability. Furthermore, the samples specific surface area, low-temperature reducibility and surface adsorbed oxygenated species ratio decreased as follows: MgCo2O4 > Co3O4 > MgO; which is completely in line with the catalytic performance trends and constitute the reasons for MgCo2O4 high excellent activity towards toluene total oxidation. The overall finding supported by ab initio molecular dynamics simulations of toluene oxidation on the Co3O4 and MgCo2O4 suggest that the catalytic process follows a Mars–van Krevelen mechanism. Full article
(This article belongs to the Special Issue Kinetics and Mechanism of Catalytic Reactions—Integrity of Experiment and Theory)
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15 pages, 2730 KiB  
Article
Effect of Water and Formic Acid on ·OH + CH4 Reaction: An Ab Initio/DFT Study
by Mohamad Akbar Ali and Balaganesh Muthiah
Catalysts 2022, 12(2), 133; https://doi.org/10.3390/catal12020133 - 21 Jan 2022
Cited by 3 | Viewed by 2683
Abstract
In this work, we used ab initio/DFT method coupled with statistical rate theory to answer the question of whether or not formic acid (HCOOH) and water molecules can catalyze the most important atmospheric and combustion prototype reaction, i.e., ·OH (OH radical) [...] Read more.
In this work, we used ab initio/DFT method coupled with statistical rate theory to answer the question of whether or not formic acid (HCOOH) and water molecules can catalyze the most important atmospheric and combustion prototype reaction, i.e., ·OH (OH radical) + CH4. The potential energy surface for ·OH + CH4 and ·OH + CH4 (+X) (X = HCOOH, H2O) reactions were calculated using the combination of hybrid-density functional theory and coupled-cluster theory with Pople basis set [(CCSD(T)/ 6-311++G(3df,3pd)//M06-2X/6-311++G(3df,3pd)]. The results of this study show that the catalytic effect of HCOOH (FA) and water molecules on the ·OH + CH4 reaction has a major impact when the concentration of FA and H2O is not included. In this situation the rate constants for the CH4 + HO···HCOOH (3 × 10−9 cm3 molecule−1 s−1) reaction is ~105 times and for CH4 + H2O···HO reaction (3 × 10−14 cm3 molecule−1 s−1 at 300 K) is ~20 times higher than ·OH + CH4 (~6 × 10−15 cm3 molecule−1 s−1). However, the total effective rate constants, which include the concentration of both species in the kinetic calculation has no effect under atmospheric condition. As a result, the total effective reaction rate constants are smaller. The rate constants when taking the account of the FA and water for CH4 + HO···HCOOH (4.1 × 10−22 cm3 molecule−1 s−1) is at least seven orders magnitude and for the CH4 + H2O···HO (7.6 × 10−17 cm3 molecule−1 s−1) is two orders magnitude smaller than ·OH + CH4 reaction. These results are also consistent with previous experimental and theoretical studies on similar reaction systems. This study helps to understand how FA and water molecules change the reaction kinetic under atmospheric conditions for ·OH + CH4 reaction. Full article
(This article belongs to the Special Issue Kinetics and Mechanism of Catalytic Reactions—Integrity of Experiment and Theory)
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20 pages, 5005 KiB  
Article
New Insight into the Interplay of Method of Deposition, Chemical State of Pd, Oxygen Storage Capability and Catalytic Activity of Pd-Containing Perovskite Catalysts for Combustion of Methane
by Silva Stanchovska, Georgy Ivanov, Sonya Harizanova, Krasimir Tenchev, Ekaterina Zhecheva, Anton Naydenov and Radostina Stoyanova
Catalysts 2021, 11(11), 1399; https://doi.org/10.3390/catal11111399 - 18 Nov 2021
Cited by 1 | Viewed by 1664
Abstract
Elaboration of Pd-supported catalysts for catalytic combustion is, nowadays, considered as an imperative task to reduce the emissions of methane. This study provides new insight into the method of deposition, chemical state of Pd and oxygen storage capability of transition metal ions and [...] Read more.
Elaboration of Pd-supported catalysts for catalytic combustion is, nowadays, considered as an imperative task to reduce the emissions of methane. This study provides new insight into the method of deposition, chemical state of Pd and oxygen storage capability of transition metal ions and their effects on the catalytic reactivity of supported catalysts for the combustion of methane. The catalyst with nominal composition La(Co0.8Ni0.1Fe0.1)0.85Pd0.15O3 was supported on SiO2-modified/γ-alumina using two synthetic procedures: (i) aerosol assisted chemical vapor deposition (U-AACVD) and (ii) wet impregnation (Imp). A comparative analysis shows that a higher catalytic activity is established for supported catalyst obtained by wet impregnation, where the PdO-like phase is well dispersed and the transition metal ions display a high oxygen storage capability. The reaction pathway over both catalysts proceeds most probably through Mars–van Krevelen mechanism. The supported catalysts are thermally stable when they are aged at 505 °C for 120 h in air containing 1.2 vol.% water vapor. Furthermore, the experimentally obtained data on La(Co0.8Ni0.1Fe0.1)0.85Pd0.15O3—based catalyst, supported on monolithic substrate VDM®Aluchrom Y Hf are simulated by using a two-dimensional heterogeneous model for monolithic reactor in order to predict the performance of an industrial catalytic reactor for abatement of methane emissions. Full article
(This article belongs to the Special Issue Kinetics and Mechanism of Catalytic Reactions—Integrity of Experiment and Theory)
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18 pages, 2590 KiB  
Article
Kinetic Study on Microwave-Assisted Oligomerization of 1-Decene over a HY Catalyst
by Snunkhaem Echaroj, Channarong Asavatesanupap, Sumaeth Chavadej and Malee Santikunaporn
Catalysts 2021, 11(9), 1105; https://doi.org/10.3390/catal11091105 - 14 Sep 2021
Cited by 5 | Viewed by 2079
Abstract
A promising production route for a high-quality base stock for lubricants is the oligomerization of high molecular-weight olefins in a high energy efficiency system. Oligomerization of 1-decene (C10) was conducted in a microwave-assisted system over a HY zeolite catalyst at different [...] Read more.
A promising production route for a high-quality base stock for lubricants is the oligomerization of high molecular-weight olefins in a high energy efficiency system. Oligomerization of 1-decene (C10) was conducted in a microwave-assisted system over a HY zeolite catalyst at different reaction temperatures and times. Higher reaction temperature resulted in increasing formation of dimers and trimers. The oligomerization reaction yielded 80% conversion, 54.2% dimer product, 22.3% trimer product and 3.4% heavier product at 483 K for a reaction time of 3 h. The best fit kinetic model for the dimerization reaction was formulated from an assumption of no vacant reaction sites. For the trimerization reaction, a molecule of dimer (C20) formed on the active site, interacted with a molecule of 1-decene in the bulk solution to form a molecule of trimer (C30). Apparent activation energies for the dimerization and trimerization reactions were 70.8 ± 0.8 and 83.6 ± 0.9 kJ/mol, respectively. The C13-NMR spectrum indicated that the oligomer product contained a significant portion of highly branched hydrocarbons, causing a substantial reduction in the viscosity index compared to conventional poly-alpha olefin lubricant (PAO). Full article
(This article belongs to the Special Issue Kinetics and Mechanism of Catalytic Reactions—Integrity of Experiment and Theory)
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15 pages, 5374 KiB  
Article
Redundancy-Free Models for Mathematical Descriptions of Three-Phase Catalytic Hydrogenation of Cinnamaldehyde
by Ekaterina Borovinskaya
Catalysts 2021, 11(2), 207; https://doi.org/10.3390/catal11020207 - 04 Feb 2021
Cited by 1 | Viewed by 1969
Abstract
A new approach on how to formulate redundancy-free models for mathematical descriptions of three-phase catalytic hydrogenation of cinnamaldehyde is presented. An automatically created redundant (generalized) model is formulated according to the complete reaction network. Models based on formal kinetics and kinetics concerning the [...] Read more.
A new approach on how to formulate redundancy-free models for mathematical descriptions of three-phase catalytic hydrogenation of cinnamaldehyde is presented. An automatically created redundant (generalized) model is formulated according to the complete reaction network. Models based on formal kinetics and kinetics concerning the Langmuir-Hinshelwood theory for three-phase catalytic hydrogenation of cinnamaldehyde were investigated. Redundancy-free models were obtained as a result of a step-by-step elimination of model parameters using sensitivity and interval analysis. Starting with 24 parameters in the redundant model, the redundancy-free model based on the Langmuir-Hinshelwood mechanism contains 6 parameters, while the model based on formal kinetics includes only 4 parameters. Due to less degrees of freedom of molecular rotation in the adsorbed state, the probability of a direct conversion of cinnamaldehyde to 3-phenylpropanol according to the redundancy-free model based on Langmuir-Hinshelwood approach is practically negligible compared to the model based on formal kinetics. Full article
(This article belongs to the Special Issue Kinetics and Mechanism of Catalytic Reactions—Integrity of Experiment and Theory)
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