Editorial

2 pages, 172 KiB

Open AccessEditorial

Computational Chemistry and Catalysis: Prediction and Design

by Salah-Eddine Stiriba

Catalysts 2023, 13(5), 839; https://0-doi-org.brum.beds.ac.uk/10.3390/catal13050839 - 04 May 2023

Cited by 2 | Viewed by 1092

The combination of computational chemistry and catalysis is an insightful approach that can be utilized to predict and design a catalyst, its function and the outcome of the catalytic chemical reaction that this catalyst activates in terms of activity, selectivity and applications [...] [...] Read more.

The combination of computational chemistry and catalysis is an insightful approach that can be utilized to predict and design a catalyst, its function and the outcome of the catalytic chemical reaction that this catalyst activates in terms of activity, selectivity and applications [...] Full article

(This article belongs to the Special Issue Computational Chemistry and Catalysis: Prediction and Design)

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12 pages, 3191 KiB

Open AccessFeature PaperArticle

Insights into the Pt (111) Surface Aid in Predicting the Selective Hydrogenation Catalyst

by Tianzuo Wang, Lun Pan, Xiangwen Zhang and Ji-Jun Zou

Catalysts 2020, 10(12), 1473; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10121473 - 16 Dec 2020

Cited by 4 | Viewed by 3358

Abstract

The d-band center position of the metal catalyst is one of the most important factors for catalytic selective hydrogenation, e.g., the conversion of nitrostyrene to aminostyrene. In this work, we modulate the d-band center position of the Pt surface via H coverage manipulation [...] Read more.

The d-band center position of the metal catalyst is one of the most important factors for catalytic selective hydrogenation, e.g., the conversion of nitrostyrene to aminostyrene. In this work, we modulate the d-band center position of the Pt surface via H coverage manipulation in order to assess the highly efficient selective hydrogenation catalyst using density functional theory (DFT) calculation, which is validated experimentally. The optimal transition metal catalysts are first screened by comparing the adsorption energy values of two ideal models, nitrobenzene and styrene, and by correlating the adsorption energy with the d-band center positions. Among the ten transition metals, Pt nanoparticles have a good balance between selectivity and the conversion rate. Then, the surface hydrogen covering strategy is applied to modulate the d-band center position on the Pt (111) surface, with the increase of H coverage leading to a decline of the d-band center position, which can selectively enhance the adsorption of nitro groups. However, excessively high H coverage (e.g., 75% or 100%) with an insufficiently low d-band center position can switch the chemisorption of nitro groups to physisorption, significantly reducing the catalytic activity. Therefore, a moderate d-band center shift (ca. −2.14 eV) resulted in both high selectivity and catalytic conversion. In addition, the PtSn experimental results met the theoretical expectations. This work provides a new strategy for the design of highly efficient metal catalysts for selective hydrogenation via the modulation of the d-band center position. Full article

(This article belongs to the Special Issue Computational Chemistry and Catalysis: Prediction and Design)

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10 pages, 1433 KiB

Open AccessFeature PaperArticle

H₂ Transformations on Graphene Supported Palladium Cluster: DFT-MD Simulations and NEB Calculations

by Francesco Ferrante, Antonio Prestianni, Marco Bertini and Dario Duca

Catalysts 2020, 10(11), 1306; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10111306 - 12 Nov 2020

Cited by 10 | Viewed by 2440

Abstract

Molecular dynamics simulations based on density functional theory were employed to investigate the fate of a hydrogen molecule shot with different kinetic energy toward a hydrogenated palladium cluster anchored on the vacant site of a defective graphene sheet. Hits resulting in H₂ [...] Read more.

Molecular dynamics simulations based on density functional theory were employed to investigate the fate of a hydrogen molecule shot with different kinetic energy toward a hydrogenated palladium cluster anchored on the vacant site of a defective graphene sheet. Hits resulting in H₂ adsorption occur until the cluster is fully saturated. The influence of H content over Pd with respect to atomic hydrogen spillover onto graphene was investigated. Calculated energy barriers of ca. 1.6 eV for H-spillover suggest that the investigated Pd/graphene system is a good candidate for hydrogen storage. Full article

(This article belongs to the Special Issue Computational Chemistry and Catalysis: Prediction and Design)

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22 pages, 4034 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Deciphering the Mechanism of Silver Catalysis of “Click” Chemistry in Water by Combining Experimental and MEDT Studies

by Hicham Ben El Ayouchia, Lahoucine Bahsis, Ismail Fichtali, Luis R. Domingo, Mar Ríos-Gutiérrez, Miguel Julve and Salah-Eddine Stiriba

Catalysts 2020, 10(9), 956; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10090956 - 20 Aug 2020

Cited by 18 | Viewed by 3421

Abstract

A combined experimental study and molecular electron density theory (MEDT) analysis was carried out to investigate the click of 1,2,3-triazole derivatives by Ag(I)-catalyzed azide-alkyne cycloaddition (AgAAC) reaction as well as its corresponding mechanistic pathway. Such a synthetic protocol leads to the regioselective formation [...] Read more.

A combined experimental study and molecular electron density theory (MEDT) analysis was carried out to investigate the click of 1,2,3-triazole derivatives by Ag(I)-catalyzed azide-alkyne cycloaddition (AgAAC) reaction as well as its corresponding mechanistic pathway. Such a synthetic protocol leads to the regioselective formation of 1,4-disubstituted-1,2,3-triazoles in the presence of AgCl as catalyst and water as reaction solvent at room temperature and pressure. The MEDT was performed by applying Density Functional Theory (DFT) calculations at both B3LYP/6-31G(d,p) (LANL2DZ for Ag) and ωB97XD/6-311G(d,p) (LANL2DZ for Ag) levels with a view to decipher the observed regioselectivity in AgAAC reactions, and so to set out the number of silver(I) species and their roles in the formation of 1,4-disubstituted-1,2,3-triazoles. The comparison of the values of the energy barriers for the mono- and dinuclear Ag(I)-acetylide in the AgAAC reaction paths shows that the calculated energy barriers of dinuclear processes are smaller than those of the mononuclear one. The type of intramolecular interactions in the investigated AgAAC click chemistry reaction accounts for the regioselective formation of the 1,4-regiosisomeric triazole isomer. The ionic character of the starting compounds, namely Ag-acetylide, is revealed for the first time. This finding rules out any type of covalent interaction, involving the silver(I) complexes, along the reaction pathway. Electron localization function (ELF) topological analysis of the electronic structure of the stationary points reaffirmed the zw-type (zwitterionic-type) mechanism of the AgAAC reactions. Full article

(This article belongs to the Special Issue Computational Chemistry and Catalysis: Prediction and Design)

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19 pages, 3095 KiB

Open AccessArticle

Phoenix dactylifera L. Seed Pretreatment for Oil Extraction and Optimization Studies for Biodiesel Production Using Ce-Zr/Al-MCM-41 Catalyst

by Zainab Ibrahim Jibril, Anita Ramli, Khairulazhar Jumbri and Normawati Mohamad Yunus

Catalysts 2020, 10(7), 764; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10070764 - 09 Jul 2020

Cited by 6 | Viewed by 2721

Abstract

This work compared the effect of soaking and roasting Phoenix dactylifera L. seeds pretreatment methods on oil yield. The conversion of the Phoenix dactylifera L. seed oil to fatty acid methyl ester (FAME) was conducted via transesterification reaction using Ce-Zr/Al-MCM-41 monometallic and bimetallic [...] Read more.

This work compared the effect of soaking and roasting Phoenix dactylifera L. seeds pretreatment methods on oil yield. The conversion of the Phoenix dactylifera L. seed oil to fatty acid methyl ester (FAME) was conducted via transesterification reaction using Ce-Zr/Al-MCM-41 monometallic and bimetallic catalysts. The reaction conditions were optimized using response surface methodology based on the central composite design (RSM-CCD). The result shows a quadratic model fitting with an R² value of ~0.98% from the analysis of variance. In addition, the optimum FAME yield of 93.83% was obtained at a reaction temperature of 60.5 °C, a reaction time of 3.8 h, a catalyst concentration of 4 wt.%, and a methanol to oil molar ratio of 6.2:1 mol/mol. The effect of the regenerated catalyst was significantly maintained for five cycles. The fuel properties of the produced FAME lie within the values reported in studies, ASTM D6751, and EN14214 standards. Full article

(This article belongs to the Special Issue Computational Chemistry and Catalysis: Prediction and Design)

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19 pages, 5276 KiB

Open AccessArticle

Synthesis of HZSM-5 Rich in Paired Al and Its Catalytic Performance for Propane Aromatization

by Dezhi Shi, Sen Wang, Hao Wang, Pengfei Wang, Li Zhang, Zhangfeng Qin, Jianguo Wang, Huaqing Zhu and Weibin Fan

Catalysts 2020, 10(6), 622; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10060622 - 03 Jun 2020

Cited by 3 | Viewed by 2492

Abstract

A series of HZSM-5 catalysts with similar Si/Al_F mole ratio, textual properties and morphology, but different contents of Al_F pairs, were synthesized by controlling the Na/Al molar ratios in the precursor gel and used for propane aromatization. It is shown that [...] Read more.

A series of HZSM-5 catalysts with similar Si/Al_F mole ratio, textual properties and morphology, but different contents of Al_F pairs, were synthesized by controlling the Na/Al molar ratios in the precursor gel and used for propane aromatization. It is shown that the catalyst with a Na/Al molar ratio of 0.8 in the synthetic gel possesses the highest paired Al_F concentration (64.4%) and shows higher propane conversion (38.2%) and aromatics selectivity (19.7 wt.%). Propane pulse experiments, micro reactor activity estimation, Operando diffuse reflectance ultraviolet-visible (DR UV-vis) spectroscopy and Fourier Transform Infrared Spectroscopy (FTIR) analysis of coke species deposited on the catalysts provide evidence that Al_F pairs in the ZSM-5 framework promote oligomerization and cyclization reactions of olefins, and then produce more aromatics. Density Functional Theory (DFT) calculations demonstrate that the cyclization of olefins and hydride transfer reaction occurring on Al_F pairs in HZSM-5 zeolite show a lower free energy barrier and a higher rate constant than those on single Al_F, indicating that the structure of Al_F pairs in the HZSM-5 zeolite has a stronger electrostatic stabilization effect on the transition states than that of single Al_F. Full article

(This article belongs to the Special Issue Computational Chemistry and Catalysis: Prediction and Design)

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22 pages, 4423 KiB

Open AccessArticle

Intensification of Catalytic Processes through the Pellet Structuring: Steady-State Properties of a Bifunctional Catalyst Pellet Applied to Generic Chemical Reactions and the Direct Synthesis of DME

by Katarzyna Bizon, Krzysztof Skrzypek-Markiewicz, Dominik Pędzich and Natalia Reczek

Catalysts 2019, 9(12), 1020; https://0-doi-org.brum.beds.ac.uk/10.3390/catal9121020 - 03 Dec 2019

Cited by 14 | Viewed by 3941

Abstract

Structuring of different types of catalytic active centers at a single-pellet level appears to be a promising and powerful tool for integration and intensification of multistep solid-catalyzed chemical reactions. However, the enhancement in the product yield and selectivity strongly depends on the proper [...] Read more.

Structuring of different types of catalytic active centers at a single-pellet level appears to be a promising and powerful tool for integration and intensification of multistep solid-catalyzed chemical reactions. However, the enhancement in the product yield and selectivity strongly depends on the proper choice of the distribution of different catalysts within the pellet. To demonstrate potential benefits from properly designed catalyst pellet, numerical studies were conducted with the aid of the mathematical model of a single spherical bifunctional catalyst pellet. The analysis was performed both for a system of two generic chemical reactions and for a real process, i.e., direct synthesis of dimethyl ether (DME) from synthesis gas via methanol. Evaluation of the pellet performance was done for three arrangements of the catalytic active sites within the pellet, i.e., a uniform distribution of two types of catalytic active centers in the entire volume of the pellet, and two core–shell structures. It was demonstrated that, especially for the larger pellets typical for fixed-bed applications, the product yield might be significantly improved by selecting proper catalyst arrangements within the pellet. Full article

(This article belongs to the Special Issue Computational Chemistry and Catalysis: Prediction and Design)

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17 pages, 4865 KiB

Open AccessFeature PaperArticle

Clicking Azides and Alkynes with Poly(pyrazolyl)borate-Copper(I) Catalysts: An Experimental and Computational Study

by Lahoucine Bahsis, Hicham Ben El Ayouchia, Hafid Anane, Carmen Ramirez de Arellano, Abdeslem Bentama, El Mestafa El Hadrami, Miguel Julve, Luis R. Domingo and Salah-Eddine Stiriba

Catalysts 2019, 9(8), 687; https://0-doi-org.brum.beds.ac.uk/10.3390/catal9080687 - 14 Aug 2019

Cited by 8 | Viewed by 3451

Abstract

The synthesis of 1,4-disubstituted-1,2,3-triazoles under a copper(I)-catalyzed azide–alkyne cycloaddition (CuAAC) regime was accomplished in high yields and a regioselective manner by using two homoscorpionate poly(pyrazolyl)borate anions: tris(pyrazolyl)hydroborate (HB(pz)₃⁻) and bis(pyrazolyl)hydroborate (H₂B(pz)₂⁻), which stabilized in situ [...] Read more.

The synthesis of 1,4-disubstituted-1,2,3-triazoles under a copper(I)-catalyzed azide–alkyne cycloaddition (CuAAC) regime was accomplished in high yields and a regioselective manner by using two homoscorpionate poly(pyrazolyl)borate anions: tris(pyrazolyl)hydroborate (HB(pz)₃⁻) and bis(pyrazolyl)hydroborate (H₂B(pz)₂⁻), which stabilized in situ the catalytically active copper (I) center. The [3+2] cycloaddition (32CA) reactions took place under strict click conditions, including room temperature and a mixture of environmentally benign solvents such as water/ethanol in a 1:1 (v/v) ratio. These click chemistry conditions were applied to form complex 1,2,3-triazoles-containing sugar moieties, which are potentially relevant from a biological point of view. Computational modeling carried out by DFT methodologies at the B3LYP/6-31G(d) level showed that the coordination of poly(pyrazolyl)borate-copper(I) to alkyne groups produced relevant changes in terms of generating a high polar copper(I)-acetylide intermediates. The analysis of the global and local reactivity indices explains correctly the role of poly(pyrazolyl)borate ligands in the stabilization and activation of the copper(I) catalyst in the studied 32CA reactions. Full article

(This article belongs to the Special Issue Computational Chemistry and Catalysis: Prediction and Design)

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15 pages, 2044 KiB

Open AccessArticle

Screening of Additives to Ni-Based Methanation Catalyst for Enhanced Anti-Sintering Performance

by Yuting Li, Xiaoxia Han, Chaofan Zhao, Lin Yue, Jinxian Zhao and Jun Ren

Catalysts 2019, 9(6), 493; https://0-doi-org.brum.beds.ac.uk/10.3390/catal9060493 - 28 May 2019

Cited by 4 | Viewed by 2578

Abstract

The resistance to sintering of Ni/Al₂O₃ catalysts with different additives for methanation reaction was modeled and predicted by data mining. In the screening, the resistance to sintering of Na, Ca, Ce, Mg, La, Cu, Zn, Zr, In, Mo, and Ti [...] Read more.

The resistance to sintering of Ni/Al₂O₃ catalysts with different additives for methanation reaction was modeled and predicted by data mining. In the screening, the resistance to sintering of Na, Ca, Ce, Mg, La, Cu, Zn, Zr, In, Mo, and Ti promoted Ni/Al₂O₃ catalyst were measured in terms of the increased rate of the size of the metallic nickel particles. The resistance to sintering of catalysts, described by the increased rate of Ni particle size as well as basic physicochemical properties of the 11 selected elements, was adopted for optimization model construction by data mining. Through regression model prediction and experimental verification, Cs was found to be an additive, and promotes the resistance to sintering mostly for Ni/Al₂O₃ catalysts. This result provides further evidence that data mining techniques can be employed as a highly efficient tool for the discovery of new catalysts in comparison with the traditional experimental method. Full article

(This article belongs to the Special Issue Computational Chemistry and Catalysis: Prediction and Design)

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