Encapsulation of Reactive Nanoparticles of Aluminum, Magnesium, Zinc, Titanium, or Boron within Polymers for Energetic Applications

2019 ◽  
Vol 3 (1) ◽  
pp. 3-13 ◽  
Author(s):  
Wenhui Zeng ◽  
Calvin O. Nyapete ◽  
Alexander H.H. Benziger ◽  
Paul A. Jelliss ◽  
Steven W. Buckner
Keyword(s):  
Metal Nanoparticles ◽  
Energy Content ◽  
High Surface ◽  
High Energy ◽  
Reactive Metal ◽  
Surface Areas ◽  
Nanoparticle Surface ◽  
Methods Of Synthesis ◽  
Primary Focus

Background: There is increasing academic and industrial interest in fabricating reactive metal and metalloid nanoparticles for a number of energetics applications. Objective: Because of inherent thermodynamic instability, the greatest challenge for producing such metal nanoparticles is to kinetically stabilize their high surface areas toward reactive atmospheric constituents. Such stabilization can effectively produce nanocomposite materials that retain their high energy content or other useful properties with a respectable shelf-life. The primary focus is to summarize methods of synthesis and characterization of these energetically valuable nanoparticles. Method and Results: Method and Results: A popular and convenient method to passivate and protect reactive metal nanoparticles is to either graft pre-assembled polymer molecules to the nanoparticle surface or use the reactive nanoparticle surface to initiate and propagate oligomer or polymer growth. Conclusion: Reactive nanoparticles composed of aluminum, magnesium, zinc, titanium, or boron may be effectively passivated, capped, and protected by a variety of organic polymers. Such treatment mitigates degradation due to atmospheric reaction, while retaining the unique properties associated with the metal-polymer nanocomposites.

Synthesis and Characterization of Aerogel-derived Cation-substituted Hexaaluminates

1996 ◽  
Vol 457 ◽  
Author(s):  
Lin-chiuan Yan ◽  
Levi T. Thompson
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Catalytic Combustion ◽  
High Surface ◽  
High Surface Area ◽  
Synthesis And Characterization ◽  
New Methods ◽  
Surface Areas ◽  
Different Characteristics

ABSTRACTNew methods have been developed for the synthesis of high surface area cation-substituted hexaaluminates. These materials were prepared by calcining high temperature (ethanol extraction) or low temperature (CO2 extraction) aerogels at temperatures up to 1600°C. Cation-substituted hexaaluminates have emerged as promising catalysts for use in high temperature catalytic combustion. In comparing unsubstituted and cation-substituted hexaaluminates, we found that the phase transformations were much cleaner for the cation-substituted materials. BaCO3 and BaAl2O4 were intermediates during transformation of the unsubstituted materials, while the cation-substituted materials transformed directly from an amorphous phase to crystalline hexaaluminate. Moreover, the presence of substitution cations caused the transformation to occur at lower temperatures. Mn seems to be a better substitution cation than Co since the Mn-substituted materials exhibited higher surface areas and better heat resistances than the Co-substituted materials. The low temperature aerogel-derived materials possessed quite different characteristics from the high temperature aerogel-derived materials. For example, phase transformation pathways were different.

scholarly journals Effects of Amorphous Ti–Al–B Nanopowder Additives on Combustion in a Single-Cylinder Diesel Engine

2017 ◽  
Vol 139 (9) ◽  
Author(s):  
Brian T. Fisher ◽  
Jim S. Cowart ◽  
Michael R. Weismiller ◽  
Zachary J. Huba ◽  
Albert Epshteyn
Keyword(s):  
Diesel Engine ◽  
Fuel Consumption ◽  
Energy Content ◽  
High Energy ◽  
Constant Load ◽  
High Specific Surface Area ◽  
Naval Research ◽  
Reactive Metal ◽  
Maximum Heat ◽  
Single Cylinder

Energetic nanoparticles are promising fuel additives due to their high specific surface area, high energy content, and catalytic capability. Novel amorphous reactive mixed-metal nanopowders (RMNPs) containing Ti, Al, and B, synthesized via a sonochemical reaction, have been developed at the Naval Research Laboratory. These materials have higher energy content than commercial nano-aluminum (nano-Al), making them potentially useful as energy-boosting fuel components. This work examines combustion of RMNPs in a single-cylinder diesel engine (Yanmar L48V). Fuel formulations included up to 4 wt % RMNPs suspended in JP-5, and equivalent nano-Al suspensions for comparison. Although the effects were small, both nano-Al and RMNPs resulted in shorter ignition delays, retarded peak pressure locations, decreased maximum heat release rates, and increased burn durations. A similar but larger engine (Yanmar L100V) was used to examine fuel consumption and emissions for a suspension of 8 wt % RMNPs in JP-5 (and 8 wt % nano-Al for comparison). The engine was operated as a genset under constant load with nominal gross indicated mean effective pressure of 6.5 bar. Unfortunately, the RMNP suspension led to deposits on the injector tip around the orifices, while nano-Al suspensions led to clogging in the fuel reservoir and subsequent engine stall. Nevertheless, fuel consumption rate was 17% lower for the nano-Al suspension compared to baseline JP-5 for the time period prior to stall, which demonstrates the potential value of reactive metal powder additives in boosting volumetric energy density of hydrocarbon fuels.

The Characterization of the Low-Index α-Al203 Surfaces by REM

1990 ◽  
Vol 48 (1) ◽  
pp. 328-329
Author(s):  
Yootaek Kim
Keyword(s):  
High Energy ◽  
X Ray Diffraction ◽  
Microscopy Observation ◽  
Basal Surface ◽  
X Ray ◽  
Surface Areas ◽  
Fair Comparison ◽  
Reflection Electron Microscopy ◽  
Atomically Flat

Four low-index surfaces; (A-surface), (0001) (basal surface), (R-surface), and of the α-Al203 single crystals were investigated by reflection electron microscopy (REM) and reflection high energy electron diffraction (RHEED) techniques[1] and the characteristics of these surfaces are reported. Specimens were prepared by polishing and annealing[2, 3], Orientation of each surface was confirmed with x-ray diffraction using a Laue camera. Microscopy observation was carried out on a JEOL JEM-200CX TEM operated at 100 KV.To facilitate a fair comparison, the surface areas which were obviously affected by a macroscopic tilt, localized contamination, etc., were avoided. Only the flat, clean, and smooth areas were compared. The surface (Fig. 1. The scale in this figure also applies to all other figures.) shows large atomically flat areas divided by steps running in <000 1> and directions. The steps in this image are not of the same height. Some are one or two atoms high and others are much higher. Fig. 2 shows the surface which is periodically facetted. One type of the facets is flat and atomically smooth while the other type is rough. The (0001) planes display curved and/or straight steps[4]. An example of curved step configuration is shown in Fig. 3. Most of the steps in this image have the same height. This step configuration is similar to the surface shown in Fig. 4. However, the contrast of the steps are very different; on the (0001) surfaces the steps are much darker and well-defined. A summary of these four surfaces is presented in the table below.

Preparation and characterization of highly active nanosized strontium-doped lanthanum cobaltate catalysts with high surface areas

2006 ◽  
Vol 51 (14) ◽  
pp. 1673-1681 ◽  
Author(s):  
Jianrong Niu ◽  
Wei Liu ◽  
Hongxing Dai ◽  
Hong He ◽  
Xuehong Zi ◽  
...  
Keyword(s):  
High Surface ◽  
Surface Areas ◽  
Highly Active

scholarly journals Production and Characterization of Molecular Dications: Experimental and Theoretical Efforts

Molecules ◽  
2020 ◽  
Vol 25 (18) ◽  
pp. 4157
Author(s):  
Stefano Falcinelli ◽  
Marzio Rosi
Keyword(s):  
Review Paper ◽  
Molecular Level ◽  
Energy Content ◽  
Plasma Chemistry ◽  
High Energy ◽  
Upper Atmosphere ◽  
Translational Energy ◽  
Research Groups ◽  
Doubly Charged

Molecular dications are doubly charged cations of importance in flames, plasma chemistry and physics and in the chemistry of the upper atmosphere of Planets. Furthermore, they are exotic species able to store a considerable amount of energy at a molecular level. This high energy content of several eV can be easily released as translational energy of the two fragment monocations generated by their Coulomb explosion. For such a reason, they were proposed as a new kind of alternative propellant. The present topic review paper reports on an overview of the main contributions made by the authors’ research groups in the generation and characterization of simple molecular dications during the last 40 years of coupling experimental and theoretical efforts.

scholarly journals Synopsis of Factors Affecting Hydrogen Storage in Biomass-Derived Activated Carbons

2021 ◽  
Vol 13 (4) ◽  
pp. 1947
Author(s):  
Al Ibtida Sultana ◽  
Nepu Saha ◽  
M. Toufiq Reza
Keyword(s):  
Surface Area ◽  
Storage Temperature ◽  
Activated Carbons ◽  
Energy Content ◽  
High Surface ◽  
High Energy ◽  
Heat Of Adsorption ◽  
Morphological Properties ◽  
Potential Cost ◽  
Widespread Application

Hydrogen (H2) is largely regarded as a potential cost-efficient clean fuel primarily due to its beneficial properties, such as its high energy content and sustainability. With the rising demand for H2 in the past decades and its favorable characteristics as an energy carrier, the escalating USA consumption of pure H2 can be projected to reach 63 million tons by 2050. Despite the tremendous potential of H2 generation and its widespread application, transportation and storage of H2 have remained the major challenges of a sustainable H2 economy. Various efforts have been undertaken by storing H2 in activated carbons, metal organic frameworks (MOFs), covalent organic frameworks (COFs), etc. Recently, the literature has been stressing the need to develop biomass-based activated carbons as an effective H2 storage material, as these are inexpensive adsorbents with tunable chemical, mechanical, and morphological properties. This article reviews the current research trends and perspectives on the role of various properties of biomass-based activated carbons on its H2 uptake capacity. The critical aspects of the governing factors of H2 storage, namely, the surface morphology (specific surface area, pore volume, and pore size distribution), surface functionality (heteroatom and functional groups), physical condition of H2 storage (temperature and pressure), and thermodynamic properties (heat of adsorption and desorption), are discussed. A comprehensive survey of the literature showed that an “ideal” biomass-based activated carbon sorbent with a micropore size typically below 10 Å, micropore volume greater than 1.5 cm3/g, and high surface area of 4000 m2/g or more may help in substantial gravimetric H2 uptake of >10 wt% at cryogenic conditions (−196 °C), as smaller pores benefit by stronger physisorption due to the high heat of adsorption.

Synthesis and Characterization of Molecular Sieve SBA-15 and Catalysts Co/SBA-15 and Ru/Co/SBA-15

2014 ◽  
Vol 798-799 ◽  
pp. 100-105 ◽  
Author(s):  
Jocielys Jovelino Rodrigues ◽  
Liliane Andrade Lima ◽  
Gustavo Medeiros de Paula ◽  
Meiry Glaúcia Freire Rodrigues
Keyword(s):  
Molecular Sieve ◽  
High Surface ◽  
Nitrogen Adsorption ◽  
Synthesis And Characterization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Surface Areas ◽  
Bet Method ◽  
Superficial Area

A series of mesoporous materials have been synthesized in an acid medium, with various structures, such as SBA-15. These materials have many properties which make them potential catalysts. Among these we highlight their high surface areas and pore walls relatively thick, resulting in a greater hydrothermal stability. This work aims at the synthesis and characterization of molecular sieve SBA-15 with molar composition: 1.0 TEOS: 0.017 P123: 5.7 HCl: 193 H2O and Co/SBA-15 and catalysts for the reaction of Ru/Co/SBA-15 Fischer Tropsch process. The materials were characterized by the techniques of X-ray diffraction (XRD), chemical analysis by X-ray spectrometry, energy dispersive (EDX) and Nitrogen adsorption (BET method). X-ray diffraction showed that the calcined cobalt catalyst did not modify the structure of SBA-15 and that Co was present under the form of Co3O4 in the catalyst. The addition of cobalt in the SBA-15 decreased the specific superficial area of the molecular sieve.

Synthesis, Characterization of Bimetallic V-Fe-SBA-15 and Its Catalytic Performance in the Hydroxylation of Phenol

2007 ◽  
Vol 7 (12) ◽  
pp. 4508-4514 ◽  
Author(s):  
Fei Gao ◽  
Yanhua Zhang ◽  
Chunling Wang ◽  
Cheng Wu ◽  
Yan Kong ◽  
...  
Keyword(s):  
Ph Value ◽  
High Surface ◽  
Mesoporous Structure ◽  
Catalytic Performance ◽  
Hydroxylation Of Phenol ◽  
Surface Areas ◽  
Hexagonal Arrangement ◽  
Ft Ir ◽  
Catalytic Performances

A series of V-Fe incorporated-SBA-15 has been synthesized by adjustment of the pH value of the gel mixtures and characterized by using XRD, N2-adsorption, ICP, FT-IR, Raman, and UV–vis techniques. Results indicated that all samples exhibited typical hexagonal arrangement of mesoporous structure with high surface areas and the heteroatoms were probably incorporated into the framework of SBA-15. Catalytic performances of the obtained materials were evaluated in the hydroxylation of phenol with H2O2, and the catalytic results revealed that the selectivity for catechol (CAT) and hydroquinone (HQ) could be controlled by adjusting the contents of V and Fe in the samples, and an appropriate nV/nFe mol ratio in SBA-15 could approach the optimal catalytic performance.

scholarly journals Adsorption of Paracetamol and Acetylsalicylic Acid onto Commercial Activated Carbons

2008 ◽  
Vol 26 (9) ◽  
pp. 721-734 ◽  
Author(s):  
Sabina Beninati ◽  
Domenica Semeraro ◽  
Marina Mastragostino
Keyword(s):  
Acetylsalicylic Acid ◽  
Activated Carbons ◽  
High Surface ◽  
High Surface Area ◽  
Adsorption Behaviour ◽  
Actual Surface ◽  
Ph Values ◽  
Surface Areas ◽  
Molecular Sizes

The adsorption of paracetamol (PAR) and acetylsalicylic acid (ASA) onto high-surface-area, commercial activated carbons was investigated at 26°C via adsorption isotherms at different pH values, including pH 1.5 to simulate conditions existing in the stomach. A wide-ranging characterization of the carbons, including analysis of their morphology and surface chemistry, was undertaken, with the actual surface areas of the carbons available for PAR and ASA adsorption being estimated by taking the molecular sizes of the drugs into account. This provided an understanding of the differences in the drug adsorption behaviour of the carbons.

Rheological Idiosyncrasies of Elastomer/Clay Nanocomposites

2008 ◽  
Vol 18 (5) ◽  
pp. 54894-1-54894-10 ◽  
Author(s):  
Zoran Susteric ◽  
Tomaz Kos
Keyword(s):  
High Surface ◽  
Clay Nanocomposites ◽  
Rheological Characterization ◽  
Melt Mixing ◽  
Mixing Processes ◽  
Rheological Analysis ◽  
Clay Particles ◽  
Surface Areas ◽  
Montmorillonite Clays

Abstract Rheological properties of elastomeric nanocomposites with organically modified Montmorillonite clays, as possible replacements or supplements to classical active fillers, such as carbon black or silica, have been intensively studied in recent years. Possessing large specific surface areas acquired through the melt-mixing processes of elastomeric intercalation and subsequent filler exfoliation, the clay particles have indeed proved to be highly eligible reinforcing and thermally stabilizing ingredients for application in elastomers. In fact, their performance has shown to be in many respects superior to that of classical fillers, particularly owing to some unusual, though beneficial, exhibited properties. Namely, apart from uncommonly high surface activity, manifested by creation of a host of van der Waals type secondary linkages with elastomer molecules, the main curiosity of clay filler is its dissipative action. Using dynamic mechanical functions under different deformational and temperature conditions, as means for rheological characterization of nanocomposites, the foregoing nano-scale traits are clearly reflected in substantial stiffness at low strains and, unexpectedly, dwindling energy loss with increasig filler content and/or decreasing temperature. Besides, rheological analysis of this kind, together with appropriate theoretical grounds, has enabled elucidation of peculiar conduct, as well as macroscopic insight into the very nature of secondary interactions in elastomers.

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