(Ag)Pd-Fe3O4 Nanocomposites as Novel Catalysts for Methane Partial Oxidation at Low Temperature

Nanostructured composite materials based on noble mono-(Pd) or bi-metallic (Ag/Pd) particles supported on mixed iron oxides (II/III) with bulk magnetite structure (Fe3O4) have been developed in order to assess their potential for heterogeneous catalysis applications in methane partial oxidation. Advancing the direct transformation of methane into value-added chemicals is consensually accepted as the key to ensuring sustainable development in the forthcoming future. On the one hand, nanosized Fe3O4 particles with spherical morphology were synthesized by an aqueous-based reflux method employing different Fe (II)/Fe (III) molar ratios (2 or 4) and reflux temperatures (80, 95 or 110 °C). The solids obtained from a Fe (II)/Fe (III) nominal molar ratio of 4 showed higher specific surface areas which were also found to increase on lowering the reflux temperature. The starting 80 m2 g−1 was enhanced up to 140 m2 g−1 for the resulting optimized Fe3O4-based solid consisting of nanoparticles with a 15 nm average diameter. On the other hand, Pd or Pd-Ag were incorporated post-synthesis, by impregnation on the highest surface Fe3O4 nanostructured substrate, using 1–3 wt.% metal load range and maintaining a constant Pd:Ag ratio of 8:2 in the bimetallic sample. The prepared nanocomposite materials were investigated by different physicochemical techniques, such as X-ray diffraction, thermogravimetry (TG) in air or H2, as well as several compositions and structural aspects using field emission scanning and scanning transmission electron microscopy techniques coupled to energy-dispersive X-ray spectroscopy (EDS). Finally, the catalytic results from a preliminary reactivity study confirmed the potential of magnetite-supported (Ag)Pd catalysts for CH4 partial oxidation into formaldehyde, with low reaction rates, methane conversion starting at 200 °C, far below temperatures reported in the literature up to now; and very high selectivity to formaldehyde, above 95%, for Fe3O4 samples with 3 wt.% metal, either Pd or Pd-Ag.

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Photocatalytic Reduction of CO2 to Methanol Using a Copper-Zirconia Imidazolate Framework

Catalysts ◽

10.3390/catal11030346 ◽

2021 ◽

Vol 11 (3) ◽

pp. 346

Author(s):

Sonam Goyal ◽

Maizatul Shima Shaharun ◽

Ganaga Suriya Jayabal ◽

Chong Fai Kait ◽

Bawadi Abdullah ◽

...

Keyword(s):

Photoelectron Spectroscopy ◽

Catalyst Support ◽

Oxidation Potential ◽

Molar Ratio ◽

X Ray Diffraction ◽

X Ray ◽

Molar Ratios ◽

Optimum Parameters ◽

Reduction Of Co2 ◽

Enhanced Yield

A set of novel photocatalysts, i.e., copper-zirconia imidazolate (CuZrIm) frameworks, were synthesized using different zirconia molar ratios (i.e., 0.5, 1, and 1.5 mmol). The photoreduction process of CO2 to methanol in a continuous-flow stirred photoreactor at pressure and temperature of 1 atm and 25 °C, respectively, was studied. The physicochemical properties of the synthesized catalysts were studied using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) spectroscopy. The highest methanol activity of 818.59 µmol/L.g was recorded when the CuZrIm1 catalyst with Cu/Zr/Im/NH4OH molar ratio of 2:1:4:2 (mmol/mmol/mmol/M) was employed. The enhanced yield is attributed to the presence of Cu2+ oxidation state and the uniformly dispersed active metals. The response surface methodology (RSM) was used to optimize the reaction parameters. The predicted results agreed well with the experimental ones with the correlation coefficient (R2) of 0.99. The optimization results showed that the highest methanol activity of 1054 µmol/L.g was recorded when the optimum parameters were employed, i.e., stirring rate (540 rpm), intensity of light (275 W/m2) and photocatalyst loading (1.3 g/L). The redox potential value for the CuZrIm1 shows that the reduction potential is −1.70 V and the oxidation potential is +1.28 V for the photoreduction of CO2 to methanol. The current work has established the potential utilization of the imidazolate framework as catalyst support for the photoreduction of CO2 to methanol.

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Synthesis of Fe2O3/C Nanocomposite Using Microwave Assisted Calcination Method

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.896.100 ◽

2014 ◽

Vol 896 ◽

pp. 100-103 ◽

Cited By ~ 2

Author(s):

Anggi Puspita Swardhani ◽

Ferry Iskandar ◽

Abdullah Mikrajuddin ◽

Khairurrijal

Keyword(s):

Crystallite Size ◽

Average Particle Size ◽

Molar Ratio ◽

Average Particle ◽

X Ray ◽

Molar Ratios ◽

Microwave Assisted ◽

Chloride Hexahydrate ◽

Calcination Method ◽

Scherrer Method

Fe2O3/C nanocomposites were successfully synthesized using microwave assisted calcination method. Ferric (III) chloride hexahydrate (FeCl36H2O), sodium hydroxide (NaOH), and dextrose monohydrate (C6H12O6H2O) were used as precursors. A microwave oven of 2.445 GHz with a power of 600 W for 20 minutes was employed during the syntheses. Calcination was performed in a simple furnace at 350 °C for 30 min. The molar ratio of C:Fe is the only process parameter. From Scanning Electron Microscope images, the average particle size were 199 nm and 74 nm for the samples with molar ratio of C:Fe of 1:2 and 1:1, respectively. X-ray diffractometer spectra showed that the obtained samples have γ-Fe2O3 (maghemite) crystal structure. Using the Scherrer method, the crystallite size were 61.7, 58.8, 52.5, and 48.8 nm for the samples with the molar ratios of C:Fe of 1:3, 1:2, 1:1, and 2:1, respectively. It means that the crystallite size of the nanocomposite decreases with the increase of the molar ratio of carbon to iron (C:Fe). The Brunauer-Emmett-Teller characterization showed that the surface area as high as 255.6 m2/g is achieved by of the Fe2O3/C nanocomposite with the molar ratio of C:Fe of 1:1.

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Cathode Material Li [Li0.2 Mn0.44Ni0.18Co0.18]O2 Synthesized by Molten Salt Method

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.690-693.981 ◽

2013 ◽

Vol 690-693 ◽

pp. 981-984

Author(s):

Guang Xin Fan ◽

Hui Lian Li ◽

Shu Pu Dai ◽

Chuan Xiang Zhang ◽

Xue Mao Guan ◽

...

Keyword(s):

Molten Salt ◽

Specific Area ◽

Constant Current ◽

Molar Ratio ◽

Molten Salt Method ◽

X Ray Diffraction ◽

X Ray ◽

Molar Ratios ◽

Structures And Properties ◽

Constant Current Charge

In this paper, LiOH·H2O and Li2CO3, which were widely used in industry and (Mn0.533Co0.233Ni0.233) (OH)2prepared by ourselves selected as starting materials, series materials of lithium-rich layered material Li [Li0.2Mn0.44Ni0.18Co0.18]O2were obtained by a molten salt method. Their structures and properties of the materials were investigated by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) and constant current charge/discharge methods. The effects of different LiOH and Li2CO3molar ratios on the Li [Li0.2Mn0.44Ni0.18Co0.18]O2structures and properties were characterized. The results of the experiments indicate that The structures of the material such as crystal structure, the specific area, particle size distribution, tap densities were controlled by adjusting the proportion of the two lithium sources. Forthermore , when the molar ratio of LiOH and Li2CO3was 3:7, the maximum discharge capacity (214.77 mAhg-1) of the cathode was obtained.

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Structural, Surface Morphology and Optical Properties of ZnS Films by Chemical Bath Deposition at Various Zn/S Molar Ratios

Journal of Nanomaterials ◽

10.1155/2014/594952 ◽

2014 ◽

Vol 2014 ◽

pp. 1-7 ◽

Cited By ~ 6

Author(s):

Fei-Peng Yu ◽

Sin-Liang Ou ◽

Pin-Chuan Yao ◽

Bing-Rui Wu ◽

Dong-Sing Wuu

Keyword(s):

Chemical Bath Deposition ◽

Photoelectron Spectroscopy ◽

Visible Region ◽

Film Surface ◽

Optical Transmittance ◽

Molar Ratio ◽

Infrared Spectrometry ◽

X Ray ◽

Molar Ratios ◽

Zns Films

In this study, ZnS thin films were prepared on glass substrates by chemical bath deposition at various Zn/S molar ratios from 1/50 to 1/150. The effects of Zn/S molar ratio in precursor on the characteristics of ZnS films were demonstrated by X-ray diffraction, scanning electron microscopy, optical transmittance, X-ray photoelectron spectroscopy, and Fourier transform infrared spectrometry. It was found that more voids were formed in the ZnS film prepared using the precursor with Zn/S molar ratio of 1/50, and the other ZnS films showed the denser structure as the molar ratio was decreased from 1/75 to 1/150. From the analyses of chemical bonding states, the ZnS phase was indeed formed in these films. Moreover, the ZnO and Zn(OH)2also appeared due to the water absorption on film surface during deposition. This would be helpful to the junction in cell device. With changing the Zn/S molar ratio from 1/75 to 1/150, the ZnS films demonstrate high transmittance of 75–88% in the visible region, indicating the films are potentially useful in photovoltaic applications.

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Liquid petroleum gas sensing performance enhanced by CuO modification of nanocrystalline ZnO-TiO2

Materials Science-Poland ◽

10.1515/msp-2016-0083 ◽

2016 ◽

Vol 34 (3) ◽

pp. 571-581

Author(s):

R.B. Pedhekar ◽

F.C. Raghuwanshi ◽

V.D. Kapse

Keyword(s):

Thick Film ◽

Gas Sensing ◽

Molar Ratio ◽

X Ray Diffraction ◽

X Ray ◽

Molar Ratios ◽

Transmission Electron ◽

Liquid Petroleum Gas ◽

Synthesized Materials ◽

Sensing Characteristics

AbstractNanocrystalline ZnO-TiO2 (with molar ratios 9:1, 7:3, 1:1, 3:7 and 1:9) were successfully synthesized by hydrothermal method. Synthesized materials were examined with the help of X-ray diffraction and transmission electron microscope. Liquid petroleum gas sensing characteristics of the ZnO-TiO2 films were investigated at different operating temperatures. The ZnO-TiO2 thick film (with 1:1 molar ratio) exhibited good response toward liquid petroleum gas as compared to other investigated compositions. Further, liquid petroleum gas sensing characteristics of CuO modified ZnO-TiO2 thick films were investigated. 0.2 M CuO modified ZnO-TiO2 thick film exhibited excellent liquid petroleum gas sensing characteristics such as higher response (~ 1637.49 at 185 °C) with quick response time (~30 s), low recovery time (~70 s), excellent repeatability and stability at low operating temperature.

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Synthesis of Layered Octadecyltrimethylammonium-Templated Aluminosilicate and its Use as a Thickening Agentfor Lubricating Grease

10.21203/rs.3.rs-593309/v1 ◽

2021 ◽

Author(s):

Lukun Han ◽

Wenxing Niu ◽

Xinrui Zhao ◽

Hong Xu ◽

Jinxiang Dong

Keyword(s):

Molar Ratio ◽

Wear Property ◽

X Ray Diffraction ◽

Lubricating Grease ◽

X Ray ◽

Molar Ratios ◽

Simple Preparation ◽

Dropping Point ◽

27Al Mas Nmr ◽

Aluminum Silicon

Abstract We describe herein the use of octadecyltrimethylammonium-templated aluminosilicate (designated as LS) as a thickener to induce gelation. LS samples with different aluminum/silicon molar ratios (Al/Si = 0, 0.05, 0.10, 0.15, 0.20) were synthesized hydrothermally and characterized by X-ray diffraction analysis, 27Al MAS NMR spectra, elemental analysis, and scanning electron microscopy. The aluminum/silicon molar ratio was shown to be an important factor affecting the rheological properties of LS gels. With increasing Al/Si molar ratio, the viscoelasticity and structural strength of LS gel were enhanced, the dropping point increased, and the amount of oil separation decreased. LS(0.20) gel exhibited superior relative elastic character. The strength of the LS(0.20) gel was also enhanced with increasing LS(0.20) content. In SRV tests, LS(0.20) gel with different contents showed good performance in terms of load-bearing ability and anti-wear property, indicating that LS was strongly adhered on the friction surface, and thereby promoted lubrication. Owing to simple preparation, the promising rheological and tribological properties, LS gel hold great potential application in lubricating grease.

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Comparative Analysis of Aminopolycarboxylate Chelants Improves Iron Control in Acidizing Operations

10.2118/204322-ms ◽

2021 ◽

Author(s):

Ahmed Hamdy El-Kady ◽

Zheng Chai ◽

Hisham A. Nasr-El-Din

Keyword(s):

Iron Concentration ◽

Control Agent ◽

Molar Ratio ◽

X Ray ◽

Molar Ratios ◽

Iron Precipitation ◽

Ph Values ◽

Initial Iron ◽

Carbonate Cores ◽

Iron Concentrations

Abstract Aminopolycarboxylate-based chelants are used to control iron precipitation during acidizing operations by interacting directly with the iron, resulting in water-soluble complexes. This paper highlights that, in order to improve the effectiveness of iron control during acidizing operations, the type and the concentration of the chelants should be based on the formation properties and the well characteristics by comparing the cheltors’ performance as iron-control agents at different temperatures and pH environments with different levels of iron concentrations and chelant to iron molar ratios in acid (HCl). This study also addresses the interactions between the tested iron-control additives and acid, as well as the performance of the chelants in carbonate cores. Laboratory experiments were conducted to investigate the performance of nitrilotriacetic acid (NTA), glutamic acid, N, N-diacetic acid (GLDA), diethylenetriaminepentaacetic acid (DTPA), ethylenediamine-tetraacetic acid (EDTA), and hydroxyethylethylenediaminetriacetic acid (HEDTA) as iron control additives in 5 wt% HCl at pH values 0 to 4.5 to simulate carbonate acidizing at temperatures of 70 to 300°F, and initial iron concentrations of 2000 ppm. The performance of NTA and EDTA was also compared at higher initial iron concentration (4000 ppm). This work also quantified the effects of acid additives such as corrosion inhibitor and non-ionic surfactant on the chelation performance. Coreflood experiments using carbonate cores in acid with chelant helped determine its influence on permeability. Testing chelant-to-acid molar ratios of 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, and 2:1 relative to iron concentration yielded optimal values. Additional tests monitored iron precipitation in solution using an inductively coupled argon plasma (ICAP) emission spectroscopy. Precipitates were filtered and analyzed using X-ray diffraction (XRD), X-ray fluorescence (XRF), and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS). Without chelant, at 70°F and 2000 ppm initial iron concentration, precipitation began at pH 1.45 and completed by pH 2.42. At 150 and 210°F, iron precipitated at pH 0.68 and 0.3 and completed by pH 1.3 and 1, respectively. At 70°F, NTA showed a minimum of 98% chelation at pH 4.3; however, its performance declined at 150°F to 74% chelation at pH 4.24, and at 210°F to 53% chelation at pH 4.0. Although DTPA dissolves completely in live acid, precipitations occurred at partially spent acid. At pH 0.15, SEM-EDS showed that the precipitate contains as much as 13 wt% iron. Thus, DTPA is not a suitable iron-control agent. HEDTA showed a 90% chelation at 210°F and pH 4.8. GLDA's performance declined to less than 50% at 150°F. At higher iron concentrations of 4000 ppm, Na3NTA kept all iron in solution in a 5 wt% HCl up to pH 4.0 at 70°F and its performance declined to a minimum of 97% at pH 4.7 at same temperature. At 150°F, and 210°F, Na3NTA started to gradually decline at pH values greater than 3.9, and 3.5, respectively. The minimum chelation reached by NTA was 91% at pH 4.4, at 150°F, and 73% at pH 4 at 210°F. Upon comparing the NTA's results at high iron concentrations to the popular EDTA, Na4EDTA at 1-to-1 mole ratio with iron exceeded its maximum solubility in 5 wt% HCl and precipitated in the original solution. For NTA, a molar ratio of 1.4:1 is optimal at 70 and 150°F, showing chelation performance of 95% and 94%, respectively, while a molar ratio of 1.5:1 is optimal at 210°F, showing a chelation performance of 87%. This study's results improve field operations by identifying NTA and HEDTA as having the best iron-control chelation performance of the five additives tested, thus reducing guesswork and streamlining production. The work also provided recommendations for choosing the best type of iron-control agent based on solubility and coreflood analysis. The results can be used to design more efficient acidizing fluids. This work won second place in the Masters division of the 2020 Gulf Coast Regional Student Paper Contest, April 2020.

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Polymorphism of felodipine co-crystals with 4,4′-bipyridine

CrystEngComm ◽

10.1039/c4ce00756e ◽

2014 ◽

Vol 16 (29) ◽

pp. 6603-6611 ◽

Cited By ~ 18

Author(s):

Artem O. Surov ◽

Katarzyna A. Solanko ◽

Andrew D. Bond ◽

Annette Bauer-Brandl ◽

German L. Perlovich

Keyword(s):

Blocking Agent ◽

Solution Calorimetry ◽

Molar Ratio ◽

X Ray Diffraction ◽

X Ray ◽

Molar Ratios ◽

Hirshfeld Surfaces ◽

Channel Blocking ◽

Polymorphic Forms ◽

Hirshfeld Surfaces Analysis

The calcium-channel blocking agent felodipine forms co-crystals with 4,4′-bipyridine with 1 : 1 and 2 : 1 molar ratios. The co-crystal with 1 : 1 molar ratio exists in two polymorphic forms. The co-crystals polymorphism was investigated by X-ray diffraction, DSC, solution calorimetry and Hirshfeld surfaces analysis.

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Synthesis of Single-Phased BaTi2O5 Powders by Arc-Melting

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.279.44 ◽

2011 ◽

Vol 279 ◽

pp. 44-48 ◽

Cited By ~ 1

Author(s):

Jian Peng ◽

Chuan Bin Wang ◽

Ling Li ◽

Qiang Shen ◽

Lian Meng Zhang

Keyword(s):

Raman Spectra ◽

Main Phase ◽

Molar Ratio ◽

X Ray Diffraction ◽

X Ray ◽

Molar Ratios ◽

Arc Melting

Arc-melting was employed to synthesize BaTi2O5 powders by fast melting the reagent mixture of BaCO3 and TiO2 with different molar ratios (0.90~1.05:2). The influence of molar ratios of BaCO3 to TiO2 on the phase of the powders derived from arc-melting was investigated by X-ray diffraction and Raman spectra. When the molar ratio was larger than 0.95:2, a little amount of Ba-rich compound Ba2TiO4 was produced besides the main phase of BaTi2O5. Ti-rich compound Ba6Ti17O40, BaTi2O9 and TiO2 began to appear at the ratios ranging from 0.90:2 to 0.95:2. Single-phased BaTi2O5 powders were obtained by arc-melting the reagent mixture with the molar ratio of 0.95:2.

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Preparation of TiO2/CNTs Nanocomposite and its Photocatalytic Activity for Methyl Orange in Aqueous Solutions

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.130-134.1539 ◽

2011 ◽

Vol 130-134 ◽

pp. 1539-1543

Author(s):

Xuan Hui Zhang ◽

Su Juan Hu ◽

Shao Ping Tong ◽

Yuan Cheng ◽

Dan Chen ◽

...

Keyword(s):

Carbon Nanotubes ◽

Photocatalytic Activity ◽

Methyl Orange ◽

Aqueous Solutions ◽

Average Diameter ◽

Molar Ratio ◽

Molar Ratios ◽

Hydrolysis Method ◽

Transmission Electron ◽

Supernatant Liquid

TiO2/CNTs nanocomposites with different Ti/C molar ratios were prepared by a sol-hydrolysis method at 368 K, using titanium tetrachloride as a precursor and nitrified carbon nanotubes as a support. The crystal phase, morphology and microstructure of the sample were characterized by X-ray Diffraction (XRD) and High-Resolution Transmission Electron Microscope (HRTEM). The photocatalytic activity of the samples was performed by methyl orange in aqueous solutions under UV light.The supernatant liquid of methyl orange during degradation was determined by using an UV-vis spectrophotometer (UV-vis). XRD results show that the crystal phases of the sample are composed of carbon nanotubes, anatase and rutile. HRTEM results show that the average diameter of oval titania is about 4.2 nm, and it decorates on the surface of carbon nanotubes uniformly. UV-vis results show that the photocatalytic activity of the TiO2/CNTs nanocomposite with the optimum Ti/C molar ratio is much higher than that of P25. These results indicate that a synergistic effect exists between titania and carbon nanotubes in the nanocomposite.

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