scholarly journals HKUST-1-Supported Cerium Catalysts for CO Oxidation

Catalysts ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 108
Author(s):  
Michalina Stawowy ◽  
Paulina Jagódka ◽  
Krzysztof Matus ◽  
Bogdan Samojeden ◽  
Joaquin Silvestre-Albero ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thermal Stability ◽  
Co Oxidation ◽  
Cerium Oxide ◽  
Photoelectron Spectroscopy ◽  
Synthesis Method ◽  
Textural Properties ◽  
Hexadecyltrimethylammonium Bromide ◽  
Incipient Wetness Impregnation ◽  
X Ray

The synthesis method of metal–organic frameworks (MOFs) has an important impact on their properties, including their performance in catalytic reactions. In this work we report on how the performance of [Cu3(TMA)2(H2O)3]n (HKUST-1) and Ce@HKUST-1 in the reaction of CO oxidation depends on the synthesis method of HKUST-1 and the way the cerium active phase is introduced to it. The HKUST-1 is synthesised in two ways: via the conventional solvothermal method and in the presence of a cationic surfactant (hexadecyltrimethylammonium bromide (CTAB)). Obtained MOFs are used as supports for cerium oxide, which is deposited on their surfaces by applying wet and incipient wetness impregnation methods. To determine textural properties, structure, morphology, and thermal stability, the HKUST-1 supports and Ce@HKUST-1 catalysts are characterised using X-ray diffraction (XRD), N2 sorption, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), and thermogravimetric analysis (TGA). It is proven that the synthesis method of HKUST-1 has a significant impact on its morphology, surface area, and thermal stability. The synthesis method also influences the dispersion and the morphology of the deposited cerium oxide. Last but not least, the synthesis method affects the catalytic activity of the obtained material.

Effect of Cerium Oxide Nanostructures on CO Oxidation

2021 ◽  
Vol 21 (3) ◽  
pp. 1641-1652
Author(s):  
R. V. Lakshmi ◽  
Parthasarathi Bera ◽  
Kamalesh Pal ◽  
Vijay Alwera ◽  
Arup Gayen ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Co Oxidation ◽  
Cerium Oxide ◽  
Oxidation State ◽  
Photoelectron Spectroscopy ◽  
Fluorite Structure ◽  
X Ray ◽  
Rice Grains ◽  
Intermediate Phases ◽  
Xrd Patterns

Cerium oxide particles with different morphologies, namely nanoparticles, nanofibers, nanocubes, and rice grains have been prepared by simple chemical routes. The shape and size of the synthesized morphologies have been studied using field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). X-ray diffraction (XRD) and selected area electron diffraction (SAED) techniques have been used to determine their crystal phases. Both nanoparticles and nanocubes of cerium oxide exclusively crystallize in fluorite structure of CeO2 as observed in XRD patterns, whereas nanofibers and rice grains are characterized by the presence of CeO2, Ce2O3, and Ce(OH)3 phases. X-ray photoelectron spectroscopy (XPS) has been employed to evaluate Ce species present in the different cerium oxide morphologies and to estimate their relative surface concentrations. As evident from Ce 3d core level spectra cerium oxide nanoparticles and nanocubes are basically CeO2 having Ce in the +4 oxidation state along with some amount of Ce3+ species. In contrast, Ce is in +3 oxidation state on its surface in cerium oxide nanofibers and rice grains that contain intermediate phases like Ce2O3 and Ce(OH)3 as endorsed by XRD patterns. CO oxidation has been carried out over these cerium oxide morphologies and among all morphologies lowest temperature CO oxidation has been demonstrated by the nanocube morphology.

scholarly journals Efficient Adsorption of Methylene Blue by Porous Biochar Derived from Soybean Dreg Using a One-Pot Synthesis Method

Molecules ◽  
2021 ◽  
Vol 26 (3) ◽  
pp. 661
Author(s):  
Zhiwei Ying ◽  
Xinwei Chen ◽  
He Li ◽  
Xinqi Liu ◽  
Chi Zhang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Methylene Blue ◽  
Photoelectron Spectroscopy ◽  
Synthesis Method ◽  
Urban Pollution ◽  
Maximum Adsorption Capacity ◽  
One Pot ◽  
Average Pore ◽  
X Ray ◽  
Isotherm Equation

Soybean dreg is a by-product of soybean products production, with a large consumption in China. Low utilization value leads to random discarding, which is one of the important sources of urban pollution. In this work, porous biochar was synthesized using a one-pot method and potassium bicarbonate (KHCO3) with low-cost soybean dreg (SD) powder as the carbon precursor to investigating the adsorption of methylene blue (MB). The prepared samples were characterized with scanning electron microscopy (SEM), transmission electron microscopy (TEM), elemental analyzer (EA), Brunauer-Emmett-Teller (BET), X-ray diffractometer (XRD), Raman spectroscopy (Raman), Fourier transform infrared spectrometer (FTIR), and X-ray photoelectron spectroscopy (XPS). The obtained SDB-K-3 showed a high specific surface area of 1620 m2 g−1, a large pore volume of 0.7509 cm3 g−1, and an average pore diameter of 1.859 nm. The results indicated that the maximum adsorption capacity of SDB-K-3 to MB could reach 1273.51 mg g−1 at 318 K. The kinetic data were most consistent with the pseudo-second-order model and the adsorption behavior was more suitable for the Langmuir isotherm equation. This study demonstrated that the porous biochar adsorbent can be prepared from soybean dreg by high value utilization, and it could hold significant potential for dye wastewater treatment in the future.

scholarly journals Synthesis of Ce1−xPdxO2−δ Solid Solution in Molten Nitrate

Catalysts ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 640
Author(s):  
Hideaki Sasaki ◽  
Keisuke Sakamoto ◽  
Masami Mori ◽  
Tatsuaki Sakamoto
Keyword(s):  
Electron Microscopy ◽  
Solid Solution ◽  
Solid Solutions ◽  
Photoelectron Spectroscopy ◽  
Synthesis Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Co Precipitation ◽  
Ionic States

CeO2-based solid solutions in which Pd partially substitutes for Ce attract considerable attention, owing to their high catalytic performances. In this study, the solid solution (Ce1−xPdxO2−δ) with a high Pd content (x ~ 0.2) was synthesized through co-precipitation under oxidative conditions using molten nitrate, and its structure and thermal decomposition were examined. The characteristics of the solid solution, such as the change in a lattice constant, inhibition of sintering, and ionic states, were examined using X-ray diffraction (XRD), scanning electron microscopy–energy-dispersive X-ray spectroscopy (SEM−EDS), transmission electron microscopy (TEM)−EDS, and X-ray photoelectron spectroscopy (XPS). The synthesis method proposed in this study appears suitable for the easy preparation of CeO2 solid solutions with a high Pd content.

scholarly journals Photocatalytic degradation of deoxynivalenol over dendritic-like α-Fe2O3 under visible light irradiation

Toxins ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 105 ◽  
Author(s):  
Huiting Wang ◽  
Jin Mao ◽  
Zhaowei Zhang ◽  
Qi Zhang ◽  
Liangxiao Zhang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Visible Light ◽  
Photocatalytic Degradation ◽  
Visible Light Irradiation ◽  
Photoelectron Spectroscopy ◽  
High Performance ◽  
Synthesis Method ◽  
Light Irradiation ◽  
Trichothecene Mycotoxin ◽  
X Ray

Deoxynivalenol (DON) is a secondary metabolite produced by Fusarium, which is a trichothecene mycotoxin. As the main mycotoxin with high toxicity, wheat, barley, corn and their products are susceptible to contamination of DON. Due to the stability of this mycotoxin, traditional methods for DON reduction often require a strong oxidant, high temperature and high pressure with more energy consumption. Therefore, exploring green, efficient and environmentally friendly ways to degrade or reduce DON is a meaningful and challenging issue. Herein, a dendritic-like α-Fe2O3 was successfully prepared using a facile hydrothermal synthesis method at 160 °C, which was systematically characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). It was found that dendritic-like α-Fe2O3 showed superior activity for the photocatalytic degradation of DON in aqueous solution under visible light irradiation (λ > 420 nm) and 90.3% DON (initial concentration of 4.0 μg/mL) could be reduced in 2 h. Most of all, the main possible intermediate products were proposed through high performance liquid chromatography-mass spectrometry (HPLC-MS) after the photocatalytic treatment. This work not only provides a green and promising way to mitigate mycotoxin contamination but also may present useful information for future studies.

scholarly journals Catalytic Behaviour of Flame-Made CuO-CeO2 Nanocatalysts in Efficient CO Oxidation

Catalysts ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 256 ◽  
Author(s):  
Feng Zhao ◽  
Shuangde Li ◽  
Xiaofeng Wu ◽  
Renliang Yue ◽  
Weiman Li ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Water Vapor ◽  
Co Oxidation ◽  
Photoelectron Spectroscopy ◽  
Co Adsorption ◽  
Synergistic Interaction ◽  
Flame Spray ◽  
Oxidation Activity ◽  
X Ray

CuO-CeO2 nanocatalysts with varying CuO contents (1, 5, 9, 14 and 17 wt %) were prepared by one-step flame spray pyrolysis (FSP) and applied to CO oxidation. The influences of CuO content on the as-prepared catalysts were systematically characterized by X-ray diffraction (XRD), N2 adsorption-desorption at −196 °C, field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and hydrogen-temperature programmed reduction (H2-TPR). A superior CO oxidation activity was observed for the 14 wt % CuO-CeO2 catalyst, with 90% CO conversion at 98 °C at space velocity (60,000 mL × g−1 × h−1), which was attributed to abundant surface defects (lattice distortion, Ce3+, and oxygen vacancies) and high reducibility supported by strong synergistic interaction. In addition, the catalyst also displayed excellent stability and resistance to water vapor. Significantly, in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS) showed that in the CO catalytic oxidation process, the strong synergistic interaction led readily to dehydroxylation and CO adsorption on Cu+ at low temperature. Furthermore, in the feed of water vapor, although there was an adverse effect on the access of CO adsorption, there was also a positive effect on the formation of fewer carbon intermediates. All these results showed the potential of highly active and water vapor-resistive CuO-CeO2 catalysts prepared by FSP.

scholarly journals Development of a nitrogen-doped 2D material for tribological applications in the boundary-lubrication regime

2017 ◽  
Vol 8 ◽  
pp. 1476-1483 ◽  
Author(s):  
Shende Rashmi Chandrabhan ◽  
Velayudhanpillai Jayan ◽  
Somendra Singh Parihar ◽  
Sundara Ramaprabhu
Keyword(s):  
Electron Microscopy ◽  
Tribological Properties ◽  
Photoelectron Spectroscopy ◽  
Large Scale ◽  
Synthesis Method ◽  
Field Trials ◽  
Base Oil ◽  
X Ray ◽  
Nitrogen Doped ◽  
Sliding Mechanism

The present paper describes a facile synthesis method for nitrogen-doped reduced graphene oxide (N-rGO) and the application of N-rGO as an effective additive for improving the tribological properties of base oil. N-rGO has been characterized by different characterization techniques such as X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and Raman spectroscopy. N-rGO-based nanolubricants are prepared and their tribological properties are studied using a four-ball tester. The nanolubricants show excellent stability over a period of six months and a significant decrease in coefficient of friction (25%) for small amounts of N-rGO (3 mg/L). The improvement in tribological properties can be attributed to the sliding mechanism of N-rGO accompanied by the high mechanical strength of graphene. Further, the nanolubricant is prepared at large scale (700 liter) and field trials are carried out at one NTPC thermal plant in India. The implementation of the nanolubricant in an induced draft (ID) fan results in the remarkable decrease in the power consumption.

scholarly journals Facet-Dependent Reactivity of Fe2O3/CeO2 Nanocomposites: Effect of Ceria Morphology on CO Oxidation

Catalysts ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 371 ◽  
Author(s):  
Maria Lykaki ◽  
Sofia Stefa ◽  
Sόnia Carabineiro ◽  
Pavlos Pandis ◽  
Vassilis Stathopoulos ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Co Oxidation ◽  
Photoelectron Spectroscopy ◽  
Rational Design ◽  
Mixed Oxides ◽  
Specific Activity ◽  
Catalytic Performance ◽  
Catalytic Systems ◽  
X Ray ◽  
Full Characterization

Ceria has been widely studied either as catalyst itself or support of various active phases in many catalytic reactions, due to its unique redox and surface properties in conjunction to its lower cost, compared to noble metal-based catalytic systems. The rational design of catalytic materials, through appropriate tailoring of the particles’ shape and size, in order to acquire highly efficient nanocatalysts, is of major significance. Iron is considered to be one of the cheapest transition metals while its interaction with ceria support and their shape-dependent catalytic activity has not been fully investigated. In this work, we report on ceria nanostructures morphological effects (cubes, polyhedra, rods) on the textural, structural, surface, redox properties and, consequently, on the CO oxidation performance of the iron-ceria mixed oxides (Fe2O3/CeO2). A full characterization study involving N2 adsorption at –196 °C, X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), temperature programmed reduction (TPR), and X-ray photoelectron spectroscopy (XPS) was performed. The results clearly revealed the key role of support morphology on the physicochemical properties and the catalytic behavior of the iron-ceria binary system, with the rod-shaped sample exhibiting the highest catalytic performance, both in terms of conversion and specific activity, due to its improved reducibility and oxygen mobility, along with its abundance in Fe2+ species.

Pd/SiO2 Inorganic–Organic Composite Membrane Calcined Under N2 Atmosphere: Thermal Stability and H2/CO2 Separation

2019 ◽  
Vol 19 (6) ◽  
pp. 3210-3217
Author(s):  
Jing Yang ◽  
Wang-Qing Fan ◽  
Ruihua Mu ◽  
Yamei Zhao
Keyword(s):  
Electron Microscopy ◽  
Thermal Stability ◽  
Photoelectron Spectroscopy ◽  
Total Pore Volume ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
N2 Atmosphere ◽  
Bet Specific Surface Area ◽  
The Mean

A novel Pd/SiO2 inorganic–organic composite material was developed for the selective separation of H2 from a mixture of H2 and CO2. Its thermal stability and microstructure calcined under N2 atmosphere were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy and N2 sorption–desorption measurements. Pd element in Pd/SiO2 gel material exists in PdCl2 form, calcination at 350 °C can result in the complete transformation of Pd2+ to metallic Pd0. With the increase of calcination temperature, the hydrophobic Si–CH3 bands decreased in intensity. The residue of Pd/SiO2 material calcined at 800 °C was mainly composed of Si–O–Si, metallic Pd0, CSi4 and some elemental C0. The mean pore size, BET specific surface area and total pore volume of the as-prepared Pd/SiO2 material calcined at 350 °C was about 2.26 nm, 417.35 m2 g−1 and 0.288 m3 g−1, respectively. The mean H2 and CO2 permeances of the corresponding Pd/SiO2 membrane were 9.90×10−6 and 9.10×10−7 mol m−2 Pa−1 s−1, respectively, when operating at 200 °C and a pressure difference of 0.3 MPa. After the steam exposure at 200 °C for 168 h, the H2 permeance decreased by 3.23% while the H2/CO2 permselectivity increased by 2.50%.

Hydrothermal synthesis of Zeolite NaA from Kaolin

2019 ◽  
Vol 12 (05) ◽  
pp. 1950075 ◽  
Author(s):  
Peng Wang ◽  
Qi Sun ◽  
Yujiao Zhang ◽  
Jun Cao ◽  
Xingmao Li
Keyword(s):  
Electron Microscopy ◽  
Hydrothermal Synthesis ◽  
Synthesis Method ◽  
Textural Properties ◽  
Treatment Temperature ◽  
Low Grade ◽  
Tem Analysis ◽  
X Ray ◽  
Zeolite Naa ◽  
Adsorption Desorption

Zeolite NaA was successfully synthesized from low-grade kaolin via hydrothermal synthesis method. The properties of the zeolite NaA were characterized by means of X-ray diffraction (XRD), Fourier transform infrared (FTIR), X-ray fluorescence (XRF), scanning electron microscopy (SEM)-energy-dispersive spectrometry (EDS), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET), and thermogravimetry (TG)-differential thermal analysis (DTA). TEM analysis indicated the formation of body-centered cubic crystal zeolite NaA and the polycrystallinity of the zeolite NaA structure. The textural properties of the zeolite NaA were further studied by N2 adsorption-desorption technique. In addition, the TG-DTA study confirmed that the heat treatment temperature of the zeolite NaA should be controlled below 600∘C.

scholarly journals Thermal CO Oxidation and Photocatalytic CO2 Reduction over Bare and M-Al2O3 (M = Co, Ni, Cu, Rh, Pd, Ag, Ir, Pt, and Au) Cotton-Like Nanosheets

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1278
Author(s):  
Heejung Yoon ◽  
Juhyun Yang ◽  
Sojeong Park ◽  
Youngku Sohn
Keyword(s):  
Electron Microscopy ◽  
Transition Metals ◽  
Co Oxidation ◽  
Photoelectron Spectroscopy ◽  
Co2 Reduction ◽  
Data Sets ◽  
X Ray Diffraction ◽  
Oxidation Activity ◽  
X Ray ◽  
Transmission Electron

Aluminum oxide (Al2O3) has abundantly been used as a catalyst, and its catalytic activity has been tailored by loading transition metals. Herein, γ-Al2O3 nanosheets were prepared by the solvothermal method, and transition metals (M = Co, Ni, Cu, Rh, Pd, Ag, Ir, Pt, and Au) were loaded onto the nanosheets. Big data sets of thermal CO oxidation and photocatalytic CO2 reduction activities were fully examined for the transition metal-loaded Al2O3 nanosheets. Their physicochemical properties were examined by scanning electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction crystallography, and X-ray photoelectron spectroscopy. It was found that Rh, Pd, Ir, and Pt-loading showed a great enhancement in CO oxidation activity while other metals negated the activity of bare Al2O3 nanosheets. Rh-Al2O3 showed the lowest CO oxidation onset temperature of 172 °C, 201 °C lower than that of bare γ-Al2O3. CO2 reduction experiments were also performed to show that CO, CH3OH, and CH4 were common products. Ag-Al2O3 nanosheets showed the highest performances with yields of 237.3 ppm for CO, 36.3 ppm for CH3OH, and 30.9 ppm for CH4, 2.2×, 1.2×, and 1.6× enhancements, respectively, compared with those for bare Al2O3. Hydrogen production was found to be maximized to 20.7 ppm during CO2 reduction for Rh-loaded Al2O3. The present unique pre-screening test results provided very useful information for the selection of transition metals on Al2O3-based energy and environmental catalysts.

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