scholarly journals Mesoporous Carbon Production by Nanocasting Technique Using Boehmite as a Template

Catalysts ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1132
Author(s):  
María Ortega-Franqueza ◽  
Svetlana Ivanova ◽  
María Isabel Domínguez ◽  
Miguel Ángel Centeno
Keyword(s):  
Mesoporous Carbon ◽  
Textural Properties ◽  
X Ray Diffraction ◽  
Template Removal ◽  
X Ray ◽  
Carbon Production ◽  
Transmission Electron ◽  
Phosphorus Doped ◽  
Positive Effect ◽  
Raman And Ir Spectroscopy

A series of mesoporous carbonaceous materials were synthesized by the nanocasting technique using boehmite as a template and glucose as a carbon precursor. After pyrolysis and template removal, the resulting material is a mesoporous carbon that can be additionally doped with N, B and K during prepyrolysis impregnation. In addition, the influence of doping on the morphology, crystallinity and stability of the synthesized carbons was studied using X-ray diffraction, nitrogen physisorption, thermogravimetry, Raman and IR spectroscopy and transmission electron microscopy. While the nanocasting process is effective for the formation of mesopores, KOH and urea do not modify the textural properties of carbon. The use of H3PO4 as a dopant, however, led to the formation of an AlPO4 compound and resulted in a solid with a lower specific surface area and higher microporosity. All doped solids present higher thermal stability as a positive effect of the introduction of heteroatoms to the carbon skeleton. The phosphorus-doped sample has better oxidation resistance, with a combustion temperature 120–150 °C higher than those observed for the other materials.

scholarly journals Ce- and Y-Modified Double-Layered Hydroxides as Catalysts for Dry Reforming of Methane: On the Effect of Yttrium Promotion

Catalysts ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 56 ◽  
Author(s):  
Katarzyna Świrk ◽  
Magnus Rønning ◽  
Monika Motak ◽  
Patricia Beaunier ◽  
Patrick Da Costa ◽  
...  
Keyword(s):  
Textural Properties ◽  
Dry Reforming ◽  
Dry Reforming Of Methane ◽  
Side Reactions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Temperature Programmed ◽  
Nickel Species

Ce- and Y-promoted double-layered hydroxides were synthesized and tested in dry reforming of methane (CH4/CO2 = 1/1). The characterization of the catalysts was performed using X-ray fluorescence (XRF), X-ray diffraction (XRD), N2 sorption, temperature-programmed reduction in H2 (TPR-H2), temperature-programmed desorption of CO2 (TPD-CO2), H2 chemisorption, thermogravimetric analysis coupled by mass spectrometry (TGA/MS), Raman, and high-resolution transmission electron microscopy (HRTEM). The promotion with cerium influences textural properties, improves the Ni dispersion, decreases the number of total basic sites, and increases the reduction temperature of nickel species. After promotion with yttrium, the increase in basicity is not directly correlated with the increasing Y loading on the contrary of Ni dispersion. Dry reforming of methane (DRM) was performed as a function of temperature and in isothermal conditions at 700 °C for 5 h. For catalytic tests, a slight increase of the activity is observed for both Y and Ce doped catalysts. This improvement can of course be explained by Ni dispersion, which was found higher for both Y and Ce promoted catalysts. During DRM, the H2/CO ratio was found below unity, which can be explained by side reactions occurrence. These side reactions are linked with the increase of CO2 conversion and led to carbon deposition. By HRTEM, only multi-walled and helical-shaped carbon nanotubes were identified on Y and Ce promoted catalysts. Finally, from Raman spectroscopy, it was found that on Y and Ce promoted catalysts, the formed C is less graphitic as compared to only Ce-based catalyst.

scholarly journals Synthesis, Structure, and Luminescent Properties of Europium-Doped Hydroxyapatite Nanocrystalline Powders

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Carmen Steluta Ciobanu ◽  
Simona Liliana Iconaru ◽  
Florian Massuyeau ◽  
Liliana Violeta Constantin ◽  
Adrian Costescu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Textural Properties ◽  
Average Crystallite Size ◽  
Luminescent Properties ◽  
Nanocrystalline Powders ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Vibrational Studies ◽  
20 Nm

The luminescent europium-doped hydroxyapatite (Eu:HAp, Ca10−xEux(PO4)6(OH)2) with0≤x≤0.2nanocrystalline powders was synthesized by coprecipitation. The structural, morphological, and textural properties were well characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The vibrational studies were performed by Fourier transform infrared, Raman, and photoluminescence spectroscopies. The X-ray diffraction analysis revealed that hydroxyapatite is the unique crystalline constituent of all the samples, indicating that Eu has been successfully inserted into the HAp lattice. Eu doping inhibits HAp crystallization, leading to a decrease of the average crystallite size from around 20 nm in the undoped sample to around 7 nm in the sample with the highest Eu concentration. Furthermore, the samples show the characteristic5D0→7F0transition observed at 578 nm related to Eu3+ions distributed on Ca2+sites of the apatitic structure.

Engineering Iron-Based Nanoparticles Spatially Dispersed on Mesoporous Carbon and Its Catalytic Activity for the Direct Oxidization of Benzene to Phenol

NANO ◽  
2018 ◽  
Vol 13 (08) ◽  
pp. 1850094
Author(s):  
Qiang Sun ◽  
Long Liu ◽  
Yi-Ding Li ◽  
Zeng-Rong Wang ◽  
Xue Zhang
Keyword(s):  
Mesoporous Carbon ◽  
Molecular Diffusion ◽  
Carbon Matrix ◽  
Mesoporous Structure ◽  
X Ray Diffraction ◽  
Efficient Catalyst ◽  
X Ray ◽  
Transmission Electron ◽  
Benzene Hydroxylation ◽  
Iron Based

We report engineered iron-based nanoparticles supported on cagelike mesoporous carbon that leaves its most mesopores empty to retain an open pore network and are expected to be efficient catalyst with fast molecular diffusion/transportation. The nano-scale iron-based particle inlayed in mesoporous carbon catalyst was obtained via the introduction of N atoms as an anchor. Results of X-ray diffraction, N2 sorption and transmission electron microscopy showed that the cagelike mesoporous structure of the carbon matrix was retained during catalyst preparation and iron-based nanoparticles were spatially dispersed on the mesoporous carbon. Importantly, it was found that the obtained iron-based nanoparticles inlayed into mesoporous carbon with a low Fe loading of 1.26[Formula: see text]wt.% was an appropriate catalyst for the benzene hydroxylation to phenol using H2O2 as the oxidant. At a low temperature of 30∘C, 19.4% conversion to benzene and 14.6% phenol yield were obtained; in addition, the catalyst could be recycled at least four times.

Preparation and Electrochemical Characteristics of Nitrogen-Doped Mesoporous Carbon Using Surfactants as Carbon Source

2011 ◽  
Vol 239-242 ◽  
pp. 2573-2577
Author(s):  
Guan Gui Yi ◽  
Ying Liang Liu ◽  
Yong Xiao ◽  
Wen Qi He ◽  
Shuai Zhao
Keyword(s):  
Carbon Source ◽  
Mesoporous Carbon ◽  
Electrode Materials ◽  
Electrochemical Capacitor ◽  
Electrochemical Characteristics ◽  
X Ray Diffraction ◽  
Electrochemical Behaviors ◽  
X Ray ◽  
Nitrogen Doped ◽  
Transmission Electron

Nitrogen-doped mesoporous carbons (NMC) were prepared through a facile procedure using surfactants (polyvinylpyrrolidone) as a nitrogen-containing carbon source. The NMC samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and nitrogen sorption at 77 K. Cyclic voltammetry and galvanostatic charge/discharge experiments were adopted to investigate their electrochemical behaviors. The NMC-5 sample contain abundant mesopores shows the large specific capacitance up to 276 F g−1at the current of density of 0.1 A g-1. We suggest that the nitrogen-doped mesoporous carbon has potential application as electrochemical capacitor electrode materials.

Synthesis and Characterization of Mesoporous Carbon with MoO3 Loading via Ultrasonic Assembly

2010 ◽  
Vol 654-656 ◽  
pp. 2277-2280
Author(s):  
Xi Long ◽  
Wen Chen ◽  
Shao Jiang Chen ◽  
Chun Xia Zhao
Keyword(s):  
Electron Microscopy ◽  
Mesoporous Carbon ◽  
Nitrogen Adsorption ◽  
Photoelectron Spectra ◽  
Synthesis And Characterization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Sol Precursor

Mesoporous carbon with MoO3 loading (MoO3/CMK-3) was obtained via ultrasonic assembly with CMK-3 as the host material and MoO3 as the guest material which was yield from MoO3ּpH2O2ּqH2O sol precursor. The microstructures of such MoO3/CMK-3 composites were characterized by X-ray diffraction (XRD), nitrogen adsorption and desorption, X-ray photoelectron spectra (XPS), Fourier-transform infrared (FTIR) and transmission electron microscopy (TEM). The results show that the method of ultrasonic assembly was efficient to highly disperse MoO3 nanoparticales into the channels of mesoporous carbon.

Fabrication of Pd-Doped SiO2 Aerogels by Radiation Method

2016 ◽  
Vol 847 ◽  
pp. 308-312
Author(s):  
Ming Long Zhong ◽  
Chao Yang Wang ◽  
Zhi Bing Fu ◽  
Yong Zeng ◽  
Qi Fang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Textural Properties ◽  
Pd Nanoparticles ◽  
X Ray Diffraction ◽  
X Ray ◽  
Radiation Method ◽  
Surface Areas ◽  
Transmission Electron ◽  
Scanning Electron

The radiation method was studied to prepare Pd-doped SiO2 aerogels with different contents. The textural properties of the pristine SiO2 aerogels and Pd-doped SiO2 aerogels were systematically characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and N2 adsorption measurements. It can be concluded that there were large amounts of Pd particles presented in the framework of SiO2 aerogels after radiation. In addition, the size of Pd particles increased with the increase of radiation dose. The introduction of Pd nanoparticles produced a reduction of the surface areas, total pore and mesopore volumes.

scholarly journals Highly Dispersed Pt Nanoparticles on N-Doped Ordered Mesoporous Carbon as Effective Catalysts for Selective Hydrogenation of Nitroarenes

Catalysts ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 374 ◽  
Author(s):  
Yao Sheng ◽  
Xinrui Lin ◽  
Xueguang Wang ◽  
Xiujing Zou ◽  
Chunlei Zhang
Keyword(s):  
Selective Hydrogenation ◽  
Mesoporous Carbon ◽  
Pt Nanoparticles ◽  
Catalytic Performance ◽  
Photoelectron Spectra ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Highly Dispersed ◽  
Nitro Aromatics

Highly-dispersed Pt nanoparticles supported on nitrogen-modified CMK-3 mesoporous carbon (Pt/N-CMK-3) were first fabricated by a two-step impregnation route. The influences of N content on the catalyst porous structure, Pt nanoparticle size, surface properties, and interaction between Pt species and the support were investigated in detail using N2 sorption, X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectra (XPS). The N species acted as anchoring sites for the stabilization of Pt particles. Benefiting from the formation of ultrafine metal nanoparticles, the Pt/N-CMK-3 exhibited excellent catalytic activity and selectivity for the selective hydrogenation of nitro aromatics to the corresponding anilines with hydrogen. The Pt/N-CMK-3 catalyst could be reused eight times and keep its catalytic performance.

Solid-Phase Synthesis and Photocatalytic Property of Cobalt-Doped TiO2 Mesoporous Materials

2011 ◽  
Vol 217-218 ◽  
pp. 1462-1468 ◽  
Author(s):  
Shao You Liu ◽  
Qing Ge Feng
Keyword(s):  
Photoelectron Spectroscopy ◽  
Solid Phase ◽  
Photocatalytic Property ◽  
Textural Properties ◽  
Bet Surface Area ◽  
X Ray Diffraction ◽  
Bending Vibration ◽  
Toluene Oxidation ◽  
X Ray ◽  
Transmission Electron

Mesoporous cobalt-doped TiO2 (Co-TiO2) material has been synthesized by solid-state reaction route. The textural properties of the samples are monitored by the X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM) and energy dispersive spectroscopy(EDS), Raman spectroscopy, N2-physisorption, Fourier transform infrared spectroscopy (FT-IR), ultraviolet visible light spectroscopy (UV-Vis) and X-ray photoelectron spectroscopy(XPS). It is shown that the mesoporous Co-TiO2 is consisted of polycrystalline with some amorphous mixture and trace cobalt oxide. Cobalt has been incorporated into the framework of anatase TiO2. The bending vibration at 1124 cm-1 of Co-O-Ti bond in mesoporous Co-TiO2 material is confirmed. Interestingly, it possesses a large BET surface area (97.6 m2/g) and a narrow distribution of pore size presenting a better photocatalytic reactivity for toluene oxidation. Within 150 min irradiation, the maximum conversion (95 mol%) of toluene oxidation is obtained.

The Use of Advanced Analytical Techniques for Characterization of the Chemical, Physical, and Crystallographic Nature of a Surface

1973 ◽  
Vol 31 ◽  
pp. 132-133 ◽  
Author(s):  
R. E. Herfert
Keyword(s):  
Surface Characterization ◽  
Analytical Techniques ◽  
X Ray Diffraction ◽  
Depth Of Penetration ◽  
X Ray ◽  
The Past ◽  
Transmission Electron ◽  
Scanning Electron

Studies of the nature of a surface, either metallic or nonmetallic, in the past, have been limited to the instrumentation available for these measurements. In the past, optical microscopy, replica transmission electron microscopy, electron or X-ray diffraction and optical or X-ray spectroscopy have provided the means of surface characterization. Actually, some of these techniques are not purely surface; the depth of penetration may be a few thousands of an inch. Within the last five years, instrumentation has been made available which now makes it practical for use to study the outer few 100A of layers and characterize it completely from a chemical, physical, and crystallographic standpoint. The scanning electron microscope (SEM) provides a means of viewing the surface of a material in situ to magnifications as high as 250,000X.

A High Resolution Study of G.P. Zones in Aluminum - 4.2 at % Silver

1982 ◽  
Vol 40 ◽  
pp. 722-723 ◽  
Author(s):  
R. Gronsky
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Computer Simulations ◽  
Structural Characteristics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Resolution Study

The phenomenon of clustering in Al-Ag alloys has been extensively studied since the early work of Guinierl, wherein the pre-precipitation state was characterized as an assembly of spherical, ordered, silver-rich G.P. zones. Subsequent x-ray and TEM investigations yielded results in general agreement with this model. However, serious discrepancies were later revealed by the detailed x-ray diffraction - based computer simulations of Gragg and Cohen, i.e., the silver-rich clusters were instead octahedral in shape and fully disordered, atleast below 170°C. The object of the present investigation is to examine directly the structural characteristics of G.P. zones in Al-Ag by high resolution transmission electron microscopy.

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