scholarly journals Waste-to-Energy: Production of Fuel Gases from Plastic Wastes

Polymers ◽  
2021 ◽  
Vol 13 (21) ◽  
pp. 3672
Author(s):  
Cheuk-Fai Chow ◽  
Chow-Shing Lam ◽  
Kai-Chung Lau ◽  
Cheng-Bin Gong
Keyword(s):  
Energy Production ◽  
Density Functional ◽  
Room Temperature ◽  
Density Functional Theory Calculations ◽  
Hydrogen Atom Transfer ◽  
Waste To Energy ◽  
Mechanochemical Method ◽  
Hydrogen Atoms ◽  
Functional Theory ◽  
Polymer Wastes

A new mechanochemical method was developed to convert polymer wastes, polyethylene (PE), polypropylene (PP), and polyvinyl chloride (PVC), to fuel gases (H2, CH4, and CO) under ball-milling with KMnO4 at room temperature. By using various solid-state characterizations (XPS, SEM, EDS, FTIR, and NMR), and density functional theory calculations, it was found that the activation followed the hydrogen atom transfer (HAT) mechanism. Two metal oxidant molecules were found to abstract two separate hydrogen atoms from the α–CH and β–CH units of substrates, [–βCH2–αCH(R)–]n, where R = H in PE, R = γCH3 in PP, and R = Cl in PVC, resulting in a di-radical, [–βCH•–αC•(R)–]. Subsequently, the two unpaired electrons of the di-radical were recombined into an alkene intermediate, [–βCH =αC(R)–], which underwent further oxidation to produce H2, CH4, and CO gases.

scholarly journals Large H2O solubility in dense silica and its implications for the interiors of water-rich planets

2020 ◽  
Vol 117 (18) ◽  
pp. 9747-9754 ◽  
Author(s):  
Carole Nisr ◽  
Huawei Chen ◽  
Kurt Leinenweber ◽  
Andrew Chizmeshya ◽  
Vitali B. Prakapenka ◽  
...  
Keyword(s):  
Density Functional ◽  
High Pressures ◽  
Density Functional Theory Calculations ◽  
Mutual Solubility ◽  
Hydrogen Atoms ◽  
Functional Theory ◽  
Geochemical Cycle ◽  
High Pressures And Temperatures ◽  
State Of Matter ◽  
Formula Type

Sub-Neptunes are common among the discovered exoplanets. However, lack of knowledge on the state of matter in H2O-rich setting at high pressures and temperatures (P−T) places important limitations on our understanding of this planet type. We have conducted experiments for reactions between SiO2 and H2O as archetypal materials for rock and ice, respectively, at high P−T. We found anomalously expanded volumes of dense silica (up to 4%) recovered from hydrothermal synthesis above ∼24 GPa where the CaCl2-type (Ct) structure appears at lower pressures than in the anhydrous system. Infrared spectroscopy identified strong OH modes from the dense silica samples. Both previous experiments and our density functional theory calculations support up to 0.48 hydrogen atoms per formula unit of (Si1−xH4x)O2 (x=0.12). At pressures above 60 GPa, H2O further changes the structural behavior of silica, stabilizing a niccolite-type structure, which is unquenchable. From unit-cell volume and phase equilibrium considerations, we infer that the niccolite-type phase may contain H with an amount at least comparable with or higher than that of the Ct phase. Our results suggest that the phases containing both hydrogen and lithophile elements could be the dominant materials in the interiors of water-rich planets. Even for fully layered cases, the large mutual solubility could make the boundary between rock and ice layers fuzzy. Therefore, the physical properties of the new phases that we report here would be important for understanding dynamics, geochemical cycle, and dynamo generation in water-rich planets.

Density Functional Theory Calculations of the Radical Scavenging Activity of Alkannin Derivatives

2012 ◽  
Vol 189 ◽  
pp. 225-231
Author(s):  
Xiang Peng Guo ◽  
Rui Fa Jin
Keyword(s):  
Density Functional ◽  
Radical Scavenging Activity ◽  
Radical Scavenging ◽  
Density Functional Theory Calculations ◽  
Hydrogen Atom Transfer ◽  
Scavenging Activity ◽  
Functional Theory ◽  
Hydrogen Bond Formation ◽  
Structural And Electronic Properties ◽  
The One

The structural and electronic properties of alkannin and its derivatives and their radicals were investigated at density functional level. It turned out that the presence of the dihydroxy functionality increases the radical stability through hydrogen bond formation. The hydrogen atom transfer for alkannin derivatives is difficult to occur compared with zero compound phenol. However, alkannin derivatives appear to be good candidates for the one-electron-transfer, particularly for alkannin derivatives with –OCOCH=CH(CH3)2 and –OCOCH2CH(CH3)2 groups. It suggests that 1–7 are expected to be the promising candidates for radical scavenging activity compounds because The ionization potential (IP) values of 1–7 are lower than that of the zero compound phenol.

Theoretical Insights into the Role of Water Molecule in The Aqueous/Cu(111) Interface during Corrosion Pathway

2014 ◽  
Vol 19 (4) ◽  
pp. 235-240
Author(s):  
Jun Hu ◽  
Xiao-yong Fan ◽  
Chao-Ming Wang
Keyword(s):  
Water Molecule ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Adsorbed Water ◽  
Dipole Interaction ◽  
Hydrogen Atoms ◽  
Functional Theory ◽  
Adsorbed Water Molecule ◽  
The One

The absorption and possible reaction paths during corrosion have been systematically identified at the molecular level by us-ing density functional theory calculations. The results show that the co-adsorbed water molecule has a two-fold impact on the corrosive kinetics process. The one is the solvation effect, where water molecule affects the various reactions through ion dipole interaction, without bond fracture and formation. Another is the H-transfer mediator, where the bond of co-adsorbed water molecule breaks and regenerates in order to transfer hydrogen atoms.

Stable sodium-sulfur electrochemistry enabled by phosphorus-based complexation

2021 ◽  
Vol 118 (49) ◽  
pp. e2116184118
Author(s):  
Chuanlong Wang ◽  
Yue Zhang ◽  
Yiwen Zhang ◽  
Jianmin Luo ◽  
Xiaofei Hu ◽  
...  
Keyword(s):  
Electrochemical Properties ◽  
Density Functional ◽  
Room Temperature ◽  
Solid Phase ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Wide Range ◽  
Sulfur Battery ◽  
Sodium Sulfur Battery ◽  
Sodium Sulfur

A series of sodium phosphorothioate complexes are shown to have electrochemical properties attractive for sodium-sulfur battery applications across a wide operating temperature range. As cathode materials, they resolve a long-standing issue of cyclic liquid–solid phase transition that causes sluggish reaction kinetics and poor cycling stability in conventional, room-temperature sodium-sulfur batteries. The cathode chemistry yields 80% cyclic retention after 400 cycles at room temperature and a superior low-temperature performance down to −60 °C. Coupled experimental characterization and density functional theory calculations revealed the complex structures and electrochemical reaction mechanisms. The desirable electrochemical properties are attributed to the ability of the complexes to prevent the formation of solid precipitates over a fairly wide range of voltage.

scholarly journals Electronic and Optical Properties of Sodium Niobate: A Density Functional Theory Study

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Daniel Fritsch
Keyword(s):  
Density Functional Theory ◽  
Optical Properties ◽  
Lead Zirconate Titanate ◽  
Density Functional ◽  
Room Temperature ◽  
Structural Phase ◽  
Density Functional Theory Calculations ◽  
Sodium Niobate ◽  
Functional Theory ◽  
Electronic And Optical Properties

In recent years, much effort has been devoted to replace the most commonly used piezoelectric ceramic lead zirconate titanate Pb[ZrxTi1−x]O3 (PZT) with a suitable lead-free alternative for memory or piezoelectric applications. One possible alternative to PZT is sodium niobate as it exhibits electrical and mechanical properties that make it an interesting material for technological applications. The high-temperature simple cubic perovskite structure undergoes a series of structural phase transitions with decreasing temperature. However, particularly the phases at room temperature and below are not yet fully characterised and understood. Here, we perform density functional theory calculations for the possible phases at room temperature and below and report on the structural, electronic, and optical properties of the different phases in comparison to experimental findings.

scholarly journals A Bridging Carbonyl of Unlikely Geometry: On the True Nature of the Technetium Complex [Tc2(μ-CO)2(CO)6(NC5H5)2]

2020 ◽  
Author(s):  
Miguel Ruiz ◽  
Daniel García-Vivó
Keyword(s):  
Density Functional Theory ◽  
Title Compound ◽  
Density Functional ◽  
Room Temperature ◽  
Main Product ◽  
Density Functional Theory Calculations ◽  
Crystallographic Data ◽  
Chemical Information ◽  
Functional Theory ◽  
True Nature

The title compound was reported a decade ago by Zuhayra et al as the main product of the reaction of [Tc2(CO)10] with pyridine at room temperature. Chemical information, coupled to density functional theory calculations, have now been used to show that the "bridging carbonyls" then proposed from the crystallographic data most likely correspond to bridging hydroperoxide groups. <br>

scholarly journals Calculations of helium separation via uniform pores of stanene-based membranes

2015 ◽  
Vol 6 ◽  
pp. 2470-2476 ◽  
Author(s):  
Guoping Gao ◽  
Yan Jiao ◽  
Yalong Jiao ◽  
Fengxian Ma ◽  
Liangzhi Kou ◽  
...  
Keyword(s):  
Density Functional ◽  
Room Temperature ◽  
Experimental Validation ◽  
Noble Gas ◽  
Density Functional Theory Calculations ◽  
Honeycomb Lattice ◽  
Separation Performance ◽  
High Concentration ◽  
Functional Theory ◽  
Membrane Materials

The development of low energy cost membranes to separate He from noble gas mixtures is highly desired. In this work, we studied He purification using recently experimentally realized, two-dimensional stanene (2D Sn) and decorated 2D Sn (SnH and SnF) honeycomb lattices by density functional theory calculations. To increase the permeability of noble gases through pristine 2D Sn at room temperature (298 K), two practical strategies (i.e., the application of strain and functionalization) are proposed. With their high concentration of large pores, 2D Sn-based membrane materials demonstrate excellent helium purification and can serve as a superior membrane over traditionally used, porous materials. In addition, the separation performance of these 2D Sn-based membrane materials can be significantly tuned by application of strain to optimize the He purification properties by taking both diffusion and selectivity into account. Our results are the first calculations of He separation in a defect-free honeycomb lattice, highlighting new interesting materials for helium separation for future experimental validation.

scholarly journals A Bridging Carbonyl of Unlikely Geometry: On the True Nature of the Technetium Complex [Tc2(μ-CO)2(CO)6(NC5H5)2]

2020 ◽  
Author(s):  
Miguel Ruiz ◽  
Daniel García-Vivó
Keyword(s):  
Density Functional Theory ◽  
Title Compound ◽  
Density Functional ◽  
Room Temperature ◽  
Main Product ◽  
Density Functional Theory Calculations ◽  
Crystallographic Data ◽  
Chemical Information ◽  
Functional Theory ◽  
True Nature

The title compound was reported a decade ago by Zuhayra et al as the main product of the reaction of [Tc2(CO)10] with pyridine at room temperature. Chemical information, coupled to density functional theory calculations, have now been used to show that the "bridging carbonyls" then proposed from the crystallographic data most likely correspond to bridging hydroperoxide groups. <br>

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