Molybdenum nitrides from structures to industrial applications

Abstract Owing to their remarkable characteristics, refractory molybdenum nitride (MoN x )-based compounds have been deployed in a wide range of strategic industrial applications. This review reports the electronic and structural properties that render MoN x materials as potent catalytic surfaces for numerous chemical reactions and surveys the syntheses, procedures, and catalytic applications in pertinent industries such as the petroleum industry. In particular, hydrogenation, hydrodesulfurization, and hydrodeoxygenation are essential processes in the refinement of oil segments and their conversions into commodity fuels and platform chemicals. N-vacant sites over a catalyst’s surface are a significant driver of diverse chemical phenomena. Studies on various reaction routes have emphasized that the transfer of adsorbed hydrogen atoms from the N-vacant sites reduces the activation barriers for bond breaking at key structural linkages. Density functional theory has recently provided an atomic-level understanding of Mo–N systems as active ingredients in hydrotreating processes. These Mo–N systems are potentially extendible to the hydrogenation of more complex molecules, most notably, oxygenated aromatic compounds.

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Free and Open Source Software for Computational Chemistry Education

10.33774/chemrxiv-2021-hr1r0-v2 ◽

2021 ◽

Author(s):

Susi Lehtola ◽

Antti Karttunen

Keyword(s):

Computational Chemistry ◽

Open Source ◽

Open Source Software ◽

Density Functional ◽

Chemistry Education ◽

Tight Binding ◽

Industrial Applications ◽

Bring Your Own Device ◽

Wide Range ◽

The Masses

Abstract Long in the making, computational chemistry for the masses [J. Chem. Educ. 1996, 73, 104] is finally here. Our brief review on various free and open source software (FOSS) quantum chemistry packages points out the existence of software offering a wide range of functionality, all the way from approximate semiempirical calculations with tight-binding density functional theory to sophisticated ab initio wave function methods such as coupled-cluster theory, both for molecular and for solid-state systems. Combined with the remarkable increase in the computing power of personal devices, which now rivals that of the fastest supercomputers in the world of the 1990s, we demonstrate that a decentralized model for teaching computational chemistry is now possible thanks to FOSS computational chemistry packages, enabling students to perform reasonable modeling on their own computing devices, in the bring your own device (BYOD) scheme. FOSS software can be made trivially simple to install and keep up to date, eliminating the need for departmental support, and also enables comprehensive teaching strategies, as various algorithms' actual implementations can be used in teaching. We exemplify what kinds of calculations are feasible with four FOSS electronic structure programs, assuming only extremely modest computational resources, to illustrate how FOSS packages enable decentralized approaches to computational chemistry education within the BYOD scheme. FOSS also has further benefits: the open access to the source code of FOSS packages democratizes the science of computational chemistry, and FOSS packages can be used without limitation also beyond education, in academic and industrial applications, for example. For these reasons, we believe FOSS will become ever more pervasive in computational chemistry.

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Recent Development of Catalytic Materials for Ethylbenzene Oxidation

Journal of Nanomaterials ◽

10.1155/2020/7532767 ◽

2020 ◽

Vol 2020 ◽

pp. 1-20

Author(s):

Md. Motiar Rahman ◽

Mst. Gulshan Ara ◽

Md. Sohanur Rahman ◽

Md. Sahab Uddin ◽

May N. Bin-Jumah ◽

...

Keyword(s):

Carbonyl Compounds ◽

Thermal Condition ◽

Heterogeneous Catalysts ◽

Reactive Intermediates ◽

Industrial Applications ◽

Ethylbenzene Oxidation ◽

Substituted Benzenes ◽

Platform Chemicals ◽

Wide Range ◽

Academic Settings

Catalysts are well-known to convert alkylbenzenes at high thermal condition to a number of useful products. However, the current schemes of transformation are not suitable for the hazard-free industrial applications because their reactive intermediates are transformed to a variety of side products that often retard the optimum yield and cause environmental pollutions. It is also observed that the formation of products depends on a wide range of parameters which are extremely difficult to control and often incur extra cost. Recently, heterogeneous catalysts have received huge commercial interests for the oxidation of alkylbenzene into carbonyl compounds which are platform chemicals in various synthetics and fine chemicals. This review is an up-to-date documentary on various catalysts used for the oxidation of alkyl-substituted benzenes along with their reaction condition and selectivity profiles. This work updates our knowledge for the selection and/or design of novel catalysts for the chemists and engineers in the industrial and academic settings.

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Density Functional Theory Calculations of Atomic Hydrogen Adsorption on (3, 3) Single-Wall Carbon Nanotubes with Vacancy Defects

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.687-691.4315 ◽

2014 ◽

Vol 687-691 ◽

pp. 4315-4318

Author(s):

Zong Sheng Li

Keyword(s):

Carbon Nanotubes ◽

Density Functional Theory ◽

Hydrogen Atom ◽

Density Functional ◽

Single Wall Carbon Nanotubes ◽

Adsorbed Hydrogen ◽

Hydrogen Atoms ◽

Functional Theory ◽

Vacancy Defects ◽

Single Wall Carbon

In this paper, we have employed density functional theory (DFT) to investigate the adsorption mechanisms of atomic hydrogens on the sidewalls of (3, 3) single-wall carbon nanotubes (CNTs) which have vacancy defects. All the calculations were performed using the generalized gradient approximation (GGA) with the Perdew, Burke and Ernzerhof (PBE) correlation functional.Our results show that hydrogen atoms can chemically adsorb on the defective nanotube. Bonding energy of per hydrogen atom decreases with the number of adsorbed hydrogen atoms. The hydrogen atoms will enhance the electrical conductivity of the (3, 3) nanotube. Besides one hydrogen atom adsorbing on the nanotube with a vacancy defect (MVD), hydrogen atoms move towards the MVD of the nanotube.

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Microbial Surfactants: The Next Generation Multifunctional Biomolecules for Applications in the Petroleum Industry and Its Associated Environmental Remediation

Microorganisms ◽

10.3390/microorganisms7110581 ◽

2019 ◽

Vol 7 (11) ◽

pp. 581 ◽

Cited By ~ 13

Author(s):

Emmanuel O. Fenibo ◽

Grace N. Ijoma ◽

Ramganesh Selvarajan ◽

Chioma B. Chikere

Keyword(s):

Environmental Sustainability ◽

Environmental Remediation ◽

Petroleum Industry ◽

Acinetobacter Calcoaceticus ◽

Industrial Applications ◽

Industrial Growth ◽

Agriculture Sector ◽

Industrial Sectors ◽

Wide Range ◽

Synthetic Surfactants

Surfactants are a broad category of tensio-active biomolecules with multifunctional properties applications in diverse industrial sectors and processes. Surfactants are produced synthetically and biologically. The biologically derived surfactants (biosurfactants) are produced from microorganisms, with Pseudomonas aeruginosa, Bacillus subtilis Candida albicans, and Acinetobacter calcoaceticus as dominant species. Rhamnolipids, sophorolipids, mannosylerithritol lipids, surfactin, and emulsan are well known in terms of their biotechnological applications. Biosurfactants can compete with synthetic surfactants in terms of performance, with established advantages over synthetic ones, including eco-friendliness, biodegradability, low toxicity, and stability over a wide variability of environmental factors. However, at present, synthetic surfactants are a preferred option in different industrial applications because of their availability in commercial quantities, unlike biosurfactants. The usage of synthetic surfactants introduces new species of recalcitrant pollutants into the environment and leads to undesired results when a wrong selection of surfactants is made. Substituting synthetic surfactants with biosurfactants resolves these drawbacks, thus interest has been intensified in biosurfactant applications in a wide range of industries hitherto considered as experimental fields. This review, therefore, intends to offer an overview of diverse applications in which biosurfactants have been found to be useful, with emphases on petroleum biotechnology, environmental remediation, and the agriculture sector. The application of biosurfactants in these settings would lead to industrial growth and environmental sustainability.

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Intrinsic Stacking Interactions of Natural and Artificial Nucleobases

10.26434/chemrxiv.11400405 ◽

2019 ◽

Author(s):

Drew P. Harding ◽

Laura J. Kingsley ◽

Glen Spraggon ◽

Steven Wheeler

Keyword(s):

Gas Phase ◽

Electrostatic Interactions ◽

Density Functional ◽

Molecular Descriptors ◽

Stacking Interactions ◽

Interaction Energies ◽

Functional Theory ◽

Binding Partner ◽

Heavy Atoms ◽

Wide Range

The intrinsic (gas-phase) stacking energies of natural and artificial nucleobases were explored using density functional theory (DFT) and correlated ab initio methods. Ranking the stacking strength of natural nucleobase dimers revealed a preference in binding partner similar to that seen from experiments, namely G > C > A > T > U. Decomposition of these interaction energies using symmetry-adapted perturbation theory (SAPT) showed that these dispersion dominated interactions are modulated by electrostatics. Artificial nucleobases showed a similar stacking preference for natural nucleobases and were also modulated by electrostatic interactions. A robust predictive multivariate model was developed that quantitively predicts the maximum stacking interaction between natural and a wide range of artificial nucleobases using molecular descriptors based on computed electrostatic potentials (ESPs) and the number of heavy atoms. This model should find utility in designing artificial nucleobase analogs that exhibit stacking interactions comparable to those of natural nucleobases. Further analysis of the descriptors in this model unveil the origin of superior stacking abilities of certain nucleobases, including cytosine and guanine.

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Substituent Effects on the Thermal Decomposition of Phosphate Esters on Ferrous Surfaces

10.26434/chemrxiv.11418978.v1 ◽

2019 ◽

Author(s):

James Ewen ◽

Carlos Ayestaran Latorre ◽

Arash Khajeh ◽

Joshua Moore ◽

Joseph Remias ◽

...

Keyword(s):

Thermal Decomposition ◽

Film Formation ◽

Substituent Effects ◽

Vapour Phase ◽

Industrial Applications ◽

Phosphate Esters ◽

Antiwear Additives ◽

Formation Mechanisms ◽

Phosphate Ester ◽

Wide Range

Phosphate esters have a wide range of industrial applications, for example in tribology where they are used as vapour phase lubricants and antiwear additives. To rationally design phosphate esters with improved tribological performance, an atomic-level understanding of their film formation mechanisms is required. One important aspect is the thermal decomposition of phosphate esters on steel surfaces, since this initiates film formation. In this study, ReaxFF molecular dynamics simulations are used to study the thermal decomposition of phosphate esters with different substituents on several ferrous surfaces. On Fe3O4(001) and α-Fe(110), chemisorption interactions between the phosphate esters and the surfaces occur even at room temperature, and the number of molecule-surface bonds increases as the temperature is increased from 300 to 1000 K. Conversely, on hydroxylated, amorphous Fe3O4, most of the molecules are physisorbed, even at high temperature. Thermal decomposition rates were much higher on Fe3O4(001) and particularly α-Fe(110) compared to hydroxylated, amorphous Fe3O4. This suggests that water passivates ferrous surfaces and inhibits phosphate ester chemisorption, decomposition, and ultimately film formation. On Fe3O4(001), thermal decomposition proceeds mainly through C-O cleavage (to form surface alkyl and aryl groups) and C-H cleavage (to form surface hydroxyls). The onset temperature for C-O cleavage on Fe3O4(001) increases in the order: tertiary alkyl < secondary alkyl < primary linear alkyl ≈ primary branched alkyl < aryl. This order is in agreement with experimental observations for the thermal stability of antiwear additives with similar substituents. The results highlight surface and substituent effects on the thermal decomposition of phosphate esters which should be helpful for the design of new molecules with improved performance.

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Quasi-Barrierless Submolecular Motion in Mechanically Interlocked Carbon Nanotubes

10.26434/chemrxiv.12136248 ◽

2020 ◽

Author(s):

Julia Villalva ◽

Belén Nieto-Ortega ◽

Manuel Melle-Franco ◽

Emilio Pérez

Keyword(s):

Density Functional ◽

Close Contact ◽

Tight Binding ◽

Energetic Cost ◽

Molecular Fragments ◽

Activation Barriers ◽

Flat Surfaces ◽

Different Types ◽

Atomically Flat ◽

Derivatives Of

The motion of molecular fragments in close contact with atomically flat surfaces is still not fully understood. Does a more favourable interaction imply a larger barrier towards motion even if there are no obvious minima? Here, we use mechanically interlocked rotaxane-type derivatives of SWNTs (MINTs) featuring four different types of macrocycles with significantly different affinities for the SWNT thread as models to study this problem. Using molecular dynamics, we find that there is no direct correlation between the interaction energy of the macrocycle with the SWNT and its ability to move along or around it. Density functional tight-binding calculations reveal small (<2.5 Kcal·mol-1) activation barriers, the height of which correlates with the commensurability of the aromatic moieties in the macrocycle with the SWNT. Our results show that macrocycles in MINTs rotate and translate freely around and along SWNTs at room temperature, with an energetic cost lower than the rotation around the C−C bond in ethane.

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Efficient Prediction of Structural and Electronic Properties of Hybrid 2D Materials Using DFT and Machine Learning

10.26434/chemrxiv.6254756.v1 ◽

2018 ◽

Author(s):

Sherif Tawfik ◽

Olexandr Isayev ◽

Catherine Stampfl ◽

Joseph Shapter ◽

David Winkler ◽

...

Keyword(s):

Machine Learning ◽

Band Gap ◽

Density Functional ◽

2D Materials ◽

Van Der Waals ◽

Building Blocks ◽

Machine Learning Techniques ◽

Interlayer Distance ◽

Computational Screening ◽

Wide Range

Materials constructed from different van der Waals two-dimensional (2D) heterostructures offer a wide range of benefits, but these systems have been little studied because of their experimental and computational complextiy, and because of the very large number of possible combinations of 2D building blocks. The simulation of the interface between two different 2D materials is computationally challenging due to the lattice mismatch problem, which sometimes necessitates the creation of very large simulation cells for performing density-functional theory (DFT) calculations. Here we use a combination of DFT, linear regression and machine learning techniques in order to rapidly determine the interlayer distance between two different 2D heterostructures that are stacked in a bilayer heterostructure, as well as the band gap of the bilayer. Our work provides an excellent proof of concept by quickly and accurately predicting a structural property (the interlayer distance) and an electronic property (the band gap) for a large number of hybrid 2D materials. This work paves the way for rapid computational screening of the vast parameter space of van der Waals heterostructures to identify new hybrid materials with useful and interesting properties.

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Ab initio calculation on the Optical Properties of AA- Stacked two dimensional Graphene, Silicene, Germanene, and Stanene

International Journal of Computational Physics Series ◽

10.29167/a1i1p46-50 ◽

2018 ◽

Vol 1 (1) ◽

pp. 46-50

Author(s):

Rita John ◽

Benita Merlin

Keyword(s):

Optical Properties ◽

Band Structure ◽

Density Functional ◽

Electronic Band Structure ◽

Complex Refractive Index ◽

Single Layer ◽

Generalized Gradient ◽

Electronic Band ◽

Wide Range ◽

Optical Region

In this study, we have analyzed the electronic band structure and optical properties of AA-stacked bilayer graphene and its 2D analogues and compared the results with single layers. The calculations have been done using Density Functional Theory with Generalized Gradient Approximation as exchange correlation potential as in CASTEP. The study on electronic band structure shows the splitting of valence and conduction bands. A band gap of 0.342eV in graphene and an infinitesimally small gap in other 2D materials are generated. Similar to a single layer, AA-stacked bilayer materials also exhibit excellent optical properties throughout the optical region from infrared to ultraviolet. Optical properties are studied along both parallel (||) and perpendicular ( ) polarization directions. The complex dielectric function (ε) and the complex refractive index (N) are calculated. The calculated values of ε and N enable us to analyze optical absorption, reflectivity, conductivity, and the electron loss function. Inferences from the study of optical properties are presented. In general the optical properties are found to be enhanced compared to its corresponding single layer. The further study brings out greater inferences towards their direct application in the optical industry through a wide range of the optical spectrum.

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PLATINUM

Alloy Digest ◽

10.31399/asm.ad.pt0001 ◽

1970 ◽

Vol 19 (11) ◽

Keyword(s):

Corrosion Resistance ◽

High Temperature ◽

Heat Treating ◽

Industrial Applications ◽

High Melting ◽

High Melting Point ◽

White Metal ◽

Temperature Performance ◽

Wide Range ◽

Corrosion And Oxidation

Abstract PLATINUM is a soft, ductile, white metal which can be readily worked either hot or cold. It has a wide range of industrial applications because of its excellent corrosion and oxidation resistance and its high melting point. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: Pt-1. Producer or source: Matthey Bishop Inc..

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