scholarly journals Characteristics of High Surface Area Molybdenum Nitride and Its Activity for the Catalytic Decomposition of Ammonia

Catalysts ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 192
Author(s):  
Seo-Hyeon Baek ◽  
Kyunghee Yun ◽  
Dong-Chang Kang ◽  
Hyejin An ◽  
Min Bum Park ◽  
...  
Keyword(s):  
Surface Area ◽  
Photoelectron Spectroscopy ◽  
High Surface ◽  
High Surface Area ◽  
Catalytic Decomposition ◽  
Molybdenum Nitride ◽  
X Ray ◽  
Temperature Programmed Oxidation ◽  
Oxidation Reduction ◽  
Temperature Programmed

High surface area (>170 m2 g−1) molybdenum nitride was prepared by the temperature-programmed nitridation of α-MoO3 with pure ammonia. The process was optimized by adjusting the experimental variables: the reaction temperature, heating rate, and molar flow rate of ammonia. The physicochemical properties of the as-formed molybdenum nitride were characterized by X-ray diffraction, N2 sorption, transmission electron microscopy, temperature-programmed oxidation/reduction, and X-ray photoelectron spectroscopy. Of the experimental variables, the nitridation temperature was found to be the most critical parameter determining the surface area of the molybdenum nitride. When the prepared molybdenum nitride was exposed to air, the specific surface area rapidly decreased because of the partial oxidation of molybdenum nitride to molybdenum oxynitride. However, the surface area recovered to 90% the initial value after H2 treatment. The catalyst with the highest degree of nitridation showed the best catalytic activity, superior to that of unmodified α-MoO3, for the decomposition of ammonia because of its high surface area.

The dissociative adsorption of hydrogen sulfide over nanophase titanium dioxide

1992 ◽  
Vol 7 (10) ◽  
pp. 2840-2845 ◽  
Author(s):  
Donald D. Beck ◽  
Richard W. Siegel
Keyword(s):  
Surface Area ◽  
Photoelectron Spectroscopy ◽  
High Surface ◽  
High Surface Area ◽  
Synthesis Method ◽  
Dissociative Adsorption ◽  
Initial Activity ◽  
Adsorption Activity ◽  
Rutile Structure ◽  
Temperature Programmed

A variety of TiO2 materials, including a nanophase TiO2 powder, were evaluated for their ability to dissociatively adsorb H2S in a H2 environment. A temperature programmed desorption technique was used to determine the rate of sulfide accumulation on the surface of the samples as a measurement of initial activity. The initial activity for the gas condensation-produced nanophase TiO2 with its rutile structure was found to be greater than that for other samples of TiO2 tested. When normalized for surface area, the initial specific activities of the rutile samples studied for the dissociative adsorption of H2S were similar in magnitude, but significantly higher than those of the anatase TiO2 samples investigated. Thus, the improvement in the activity is attributed mainly to the ability of the nanophase synthesis method to produce high surface area rutile TiO2. When evaluated using x-ray photoelectron spectroscopy, the nanophase TiO2 was found to be significantly deficient in oxygen. Annealing this material in oxygen decreased the number of anion vacancies and lowered the activity. Thus, we conclude that oxygen vacancies also contribute to the H2S dissociative adsorption activity.

Hydrogen production by ammonia decomposition using high surface area Mo2N and Co3Mo3N catalysts

2016 ◽  
Vol 6 (5) ◽  
pp. 1496-1506 ◽  
Author(s):  
Seetharamulu Podila ◽  
Sharif F. Zaman ◽  
Hafedh Driss ◽  
Yahia A. Alhamed ◽  
Abdulrahim A. Al-Zahrani ◽  
...  
Keyword(s):  
Citric Acid ◽  
Hydrogen Production ◽  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Ammonia Decomposition ◽  
Molybdenum Nitride ◽  
Ammonium Heptamolybdate ◽  
Temperature Programmed

High surface area bulk molybdenum nitride catalysts were synthesized via temperature-programmed ammonolysis of an ammonium heptamolybdate and citric acid (CA) composite.

Structure Effects of High Surface Area Molybdenum Nitride Powders, Macrocrystals and Nanoparticles as Catalysts for Thiophene Desulfurization

1998 ◽  
Vol 549 ◽  
Author(s):  
K. L. Roberts ◽  
E. J. Markel
Keyword(s):  
Surface Area ◽  
Specific Activity ◽  
High Surface ◽  
High Surface Area ◽  
Lower Surface ◽  
Metal Catalysts ◽  
Molybdenum Nitride ◽  
Temperature Programmed ◽  
Thiophene Hds ◽  
N Powder

AbstractMo2N powder, macrocrystals and nanoparticles and porous Mo metal were synthesized using temperature programmed reduction of MoO3 powder and crystals with reactant feed gases consisting of NH3 N2/H2 mixtures and pure H2. The Mo-based catalysts were characterized using BET, XRD, TGA, SEM, and STM. The Mo-based catalysts were also analyzed for the hydrodesulfurization (HDS) of thiophene. The relatively lower surface area Mo2N macrocrystalline catalysts (SSA = 44 m2/g) have a greater area specific activity than that of the higher surface area Mo2N powder catalysts (SSA = 150 m2/g) for the HDS of thiophene. Mo metal catalysts have significantly lower activity for thiophene HDS than Mo 2N catalysts and the HDS selectivities of non-sulfided Mo metal catalysts are significantly different from those of Mo 2N catalysts.

Characterization of High Surface Area Silicon Oxynitrides

1992 ◽  
Vol 271 ◽  
Author(s):  
Peter W. Lednor ◽  
Rene De Ruiter ◽  
Kees A. Emeis
Keyword(s):  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Surface Area ◽  
Photoelectron Spectroscopy ◽  
High Surface ◽  
High Surface Area ◽  
X Ray ◽  
Silicon Oxynitrides

ABSTRACTHigh surface area silicon oxynitrides have been prepared by nitrida- tion of silica with ammonia. Characterization by Fourier-transform infrared spectroscopy has allowed quantitative determination of hydroxyl, amido and imido groups. Data obtained by X-ray photoelectron spectroscopy show that the nitrogen is well distributed in the surface of the materials.

scholarly journals Synthesis, characterization, and reactivity of tungsten oxynitride

1998 ◽  
Vol 13 (8) ◽  
pp. 2321-2327 ◽  
Author(s):  
Toby E. Lucy ◽  
Todd P. St. Clair ◽  
S. Ted Oyama
Keyword(s):  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
X Ray Diffraction ◽  
Heating Rates ◽  
Continuous Transformation ◽  
X Ray ◽  
Synthesis Conditions ◽  
Temperature Programmed ◽  
Temperature Programmed Reaction

High surface area tungsten oxynitride has been prepared by the temperature programmed reaction (TPR) of WO3 with NH3. All samples were characterized by x-ray diffraction (XRD), nitrogen physisorption, CO chemisorption, and elemental analysis. Samples were prepared at different heating rates (β), and a Redhead analysis yielded an activation energy for nitridation of 109 kJ mol−1. A heating rate of 0.016 K s−1 gave optimal synthesis conditions. Solid state intermediates were studied by interrupting the temperature program at various stages. No distinct suboxide phases were found using XRD. The nitridation step was determined to be a continuous transformation from oxide to oxynitride. Surface area, CO uptake, and nitrogen weight % were all found to increase as the reaction progressed. Reactivity experiments showed reasonable hydrodeoxygenation (HDO) and hydrodenitrogenation (HDN) activity, but little hydrogenation (HYD) or hydrodesulfurization (HDS) activity.

scholarly journals Green Preparation of High Surface Area Cu-Au Bimetallic Nanostructured Materials by Co-Electrodeposition in a Deep Eutectic Solvent

2021 ◽  
Author(s):  
Elena Plaza Mayoral ◽  
Paula Sebastián Pascual ◽  
Kim Nicole Dalby ◽  
Kim Degn Jensen ◽  
Ib Chorkendorff ◽  
...  
Keyword(s):  
Surface Area ◽  
Nanostructured Materials ◽  
Photoelectron Spectroscopy ◽  
Choline Chloride ◽  
High Surface ◽  
High Surface Area ◽  
Deep Eutectic Solvent ◽  
Fold Increase ◽  
Active Surface Area ◽  
X Ray

In this work we present an electrodeposition method in a deep eutectic solvent (DES) to prepare bimetallic high surface area nanostructures of Cu and Au with tunable structure and composition. The metal electrodeposition performed in green choline chloride within a urea deep eutectic solvent allows us to tailor the size, morphology and elemental composition of the deposits. We combine electrochemical methods with scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDS) to characterize the electrodeposited nanostructured materials. We assess the increase of the electroactive surface area through the analysis of the lead underpotential deposition (UPD) on the prepared films. We observe a 5 to 15-fold increase of the active surface area compared to flat surfaces of polycrystalline Cu or Au. Our work reports, for the first time, a green route for the electrodeposition of Cu-Au bimetallic nanostructures in a deep eutectic solvent.

scholarly journals Green Preparation of High Surface Area Cu-Au Bimetallic Nanostructured Materials by Co-Electrodeposition in a Deep Eutectic Solvent

2021 ◽  
Author(s):  
Elena Plaza Mayoral ◽  
Paula Sebastián Pascual ◽  
Kim Nicole Dalby ◽  
Kim Degn Jensen ◽  
Ib Chorkendorff ◽  
...  
Keyword(s):  
Surface Area ◽  
Nanostructured Materials ◽  
Photoelectron Spectroscopy ◽  
Choline Chloride ◽  
High Surface ◽  
High Surface Area ◽  
Deep Eutectic Solvent ◽  
Fold Increase ◽  
Active Surface Area ◽  
X Ray

In this work we present an electrodeposition method in a deep eutectic solvent (DES) to prepare bimetallic high surface area nanostructures of Cu and Au with tunable structure and composition. The metal electrodeposition performed in green choline chloride within a urea deep eutectic solvent allows us to tailor the size, morphology and elemental composition of the deposits. We combine electrochemical methods with scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDS) to characterize the electrodeposited nanostructured materials. We assess the increase of the electroactive surface area through the analysis of the lead underpotential deposition (UPD) on the prepared films. We observe a 5 to 15-fold increase of the active surface area compared to flat surfaces of polycrystalline Cu or Au. Our work reports, for the first time, a green route for the electrodeposition of Cu-Au bimetallic nanostructures in a deep eutectic solvent.

Facile preparation of CeO2 microspheres with high surface area by ultrasonic spray pyrolysis

2018 ◽  
Vol 7 (3) ◽  
pp. 241-247 ◽  
Author(s):  
Shou-Feng Xue ◽  
Wen-Yuan Wu ◽  
Xue Bian ◽  
Zhen-Feng Wang ◽  
Yong-Fu Wu
Keyword(s):  
Electron Microscopy ◽  
Spray Pyrolysis ◽  
Surface Area ◽  
Photoelectron Spectroscopy ◽  
High Surface ◽  
High Surface Area ◽  
Ultrasonic Spray Pyrolysis ◽  
Relative Sensitivity ◽  
X Ray ◽  
Ultrasonic Spray

Abstract CeCl3 solution was used as a precursor to prepare CeO2 microspheres by ultrasonic spray pyrolysis (USP). This is a green process that allows the transformation from CeCl3 to CeO2 without consuming any precipitant. The prepared material was investigated through various analysis technologies, such as X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high resolution TEM (HRTEM), energy dispersive X-ray spectroscopy (EDS), N2 adsorption-desorption and X-ray photoelectron spectroscopy (XPS). The prepared sample was confirmed as high purity CeO2 microspheres, and two different microstructures were observed. The microsphere surface area was 86.5 m2/g according to the Brunauer-Emmett-Teller method. The microsphere diameter ranged from 0.09 μm to 3.86 μm and the microsphere surface was covered by numerous nanoparticles. The observed nanoparticles ranged in size from 19 nm to 200 nm as determined from FESEM and HRTEM images. The concentrations of Ce4+, Ce3+, residual chloride and oxygen vacancy in CeO2 were studied by relative sensitivity factors based on the XPS results. Finally, the data suggested the possible formation mechanism of the CeO2 microsphere structure.

scholarly journals Non-Thermal Plasma-Modified Ru-Sn-Ti Catalyst for Chlorinated Volatile Organic Compound Degradation

Catalysts ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1456
Author(s):  
Yujie Fu ◽  
You Zhang ◽  
Qi Xin ◽  
Zhong Zheng ◽  
Yu Zhang ◽  
...  
Keyword(s):  
Plasma Treatment ◽  
Photoelectron Spectroscopy ◽  
High Surface ◽  
High Surface Area ◽  
Surface Oxidation ◽  
Treatment Method ◽  
X Ray ◽  
Chlorinated Volatile Organic Compounds ◽  
Volatile Organic ◽  
Doped Titania

Chlorinated volatile organic compounds (CVOCs) are vital environmental concerns due to their low biodegradability and long-term persistence. Catalytic combustion technology is one of the more commonly used technologies for the treatment of CVOCs. Catalysts with high low-temperature activity, superior selectivity of non-toxic products, and resistance to chlorine poisoning are desirable. Here we adopted a plasma treatment method to synthesize a tin-doped titania loaded with ruthenium dioxide (RuO2) catalyst, possessing enhanced activity (T90%, the temperature at which 90% of dichloromethane (DCM) is decomposed, is 262 °C) compared to the catalyst prepared by the conventional calcination method. As revealed by transmission electron microscopy, X-ray diffraction, N2 adsorption, X-ray photoelectron spectroscopy, and hydrogen temperature-programmed reduction, the high surface area of the tin-doped titania catalyst and the enhanced dispersion and surface oxidation of RuO2 induced by plasma treatment were found to be the main factors determining excellent catalytic activities.

scholarly journals Organomineral nanocomposite carbon burial during Oceanic Anoxic Event 2

2014 ◽  
Vol 11 (5) ◽  
pp. 6815-6844
Author(s):  
S. C. Löhr ◽  
M. J. Kennedy
Keyword(s):  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Mineral Surfaces ◽  
Mineral Surface ◽  
X Ray ◽  
Oceanic Anoxic Event ◽  
Carbon Burial ◽  
Anoxic Events ◽  
Mineral Surface Area

Abstract. Organic carbon (OC) enrichment in sediments deposited during Oceanic Anoxic Events (OAEs) is commonly attributed to elevated productivity and marine anoxia. We find that OC enrichment in the late Cenomanian aged OAE2 at Demerara Rise was controlled by co-occurrence of anoxic bottom-water, sufficient productivity to saturate available mineral surfaces and variable deposition of high surface area detrital smectite clay. Redox indicators show consistently oxygen-depleted conditions, while a strong correlation between OC concentration and sediment mineral surface area (R2=0.92) occurs across a range of TOC values from 9–33%. X-ray diffraction data indicates intercalation of OC in smectite interlayers while electron, synchrotron infrared and X-ray microscopy show an intimate association between clay minerals and OC, consistent with preservation of OC as organomineral nanocomposites and aggregates rather than discrete, μm-scale pelagic detritus. Since the consistent ratio between TOC and mineral surface area suggests that excess OC relative to surface area is lost, we propose that it is the varying supply of smectite that best explains variable organic enrichment against a backdrop of continuous anoxia, which is conducive to generally high TOC during OAE2 at Demerara Rise. Smectitic clays are unique in their ability to form stable organomineral nanocomposites and aggregates that preserve organic matter, and are common weathering products of continental volcanic deposits. An increased flux of smectite coinciding with high carbon burial is consistent with evidence for widespread volcanism during OAE2, so that organomineral carbon burial may represent a potential feedback to volcanic degassing of CO2.

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