scholarly journals Higher Activity of Ni/γ-Al2O3 over Fe/γ-Al2O3 and Ru/γ-Al2O3 for Catalytic Ammonia Synthesis in Nonthermal Atmospheric-Pressure Plasma of N2 and H2

Catalysts ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 590
Author(s):  
Masakazu Iwamoto ◽  
Masataka Horikoshi ◽  
Ryu Hashimoto ◽  
Kaori Shimano ◽  
Tomiko Sawaguchi ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Atmospheric Pressure ◽  
Active Sites ◽  
Ammonia Synthesis ◽  
Atmospheric Pressure Plasma ◽  
Nonthermal Plasma ◽  
Synthesis Process ◽  
Efficient Catalyst ◽  
Plasma Reaction ◽  
Activity Sequence

Developing a novel ammonia synthesis process from N2 and H2 is of interest to the catalysis and hydrogen research communities. γ-Alumina-supported nickel was determined capable of serving as an efficient catalyst for ammonia synthesis using nonthermal plasma under atmospheric pressure without heating. The catalytic activity was almost unrelated to the crystal structure and the surface area of the alumina carrier. The activity of Ni/Al2O3 was quantitatively compared with that of Fe/Al2O3 and Ru/Al2O3, which contained active metals for the conventional Haber–Bosch process. The activity sequence was Ni/Al2O3 > Al2O3 > Fe/Al2O3 > no additive > Ru/Al2O3, surprisingly indicating that the loading of Fe and Ru decreased the activity of Al2O3. The catalytic activity of Ni/Al2O3 was dependent on the amount of loaded Ni, the calcination temperature, and the reaction time. XRD, visual, and XPS observations of the catalysts before the plasma reaction indicated the generation of NiO and NiAl2O4 on Al2O3, the latter of which was generated upon high-temperature calcination. The NiO species was readily reduced to Ni metal in the plasma reaction, whereas the NiAl2O4 species was difficult to reduce. The catalytic behavior could be attributed to the production of fine Ni metal particles that served as active sites. The PN2/PH2 ratio dependence and rate constants of formation and decomposition of ammonia were finally determined for 5.0 wt% Ni/Al2O3 calcined at 773 K. The ammonia yield was 6.3% at an applied voltage of 6.0 kV, a residence time of reactant gases of 0.12 min, and PH2/PN2 = 1.

The Effect of Ni Precursor Salts on Diatomite Supported Ni-Mg Catalysts in Methanation of CO2

2021 ◽  
Vol 1016 ◽  
pp. 1417-1422
Author(s):  
Chao Sun ◽  
Jugoslav Krstic ◽  
Vojkan Radonjic ◽  
Miroslav Stankovic ◽  
Patrick da Costa
Keyword(s):  
Catalytic Activity ◽  
Atmospheric Pressure ◽  
Textural Properties ◽  
Catalytic Performance ◽  
Nickel Salt ◽  
Nitrate Salt ◽  
Efficient Catalyst ◽  
Mild Conditions ◽  
The Difference ◽  
Supported Ni

This study is aimed to investigate the effect of Ni precursor salts on the properties (textural, phase-structural, reducibility, and basicity), and catalytic performance of diatomite supported Ni-Mg catalyst in methanation of CO2. The NiMg/D-X catalysts derived from various nickel salts (X = S-sulfamate, N-nitrate or A-acetate) were synthesized by the precipitation-deposition (PD) method. The catalysts were characterized by N2-physisorption, XRD, TPR-H2, and TPD-CO2 techniques. The different catalytic activity (conversion) and selectivity, observed in CO2 methanation carried out under relatively mild conditions (atmospheric pressure; temperatures: 250-450 °C) are related and explained by the difference in textural properties, metallic Ni-crystallite size, reducibility, and basicity of studied catalysts. The results showed that catalyst derived from Ni-nitrate salt (NiMg/D-N) is more suitable for the preparation of efficient catalyst for CO2 methanation than its counterparts derived from sulfamate (NiMg/D-S) or acetate (NiMg/D-A) nickel salt. The NiMg/D-N catalyst showed the highest specific surface area and total basicity, and the best catalytic performance with CO2 conversion of 63.3 % and CH4 selectivity of 80.9 % at 450 °C.

scholarly journals In Situ Investigation of the Formation Kinematics of Plasma-Generated Silver Nanoparticles

Nanomaterials ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 555 ◽  
Author(s):  
Daniel Tasche ◽  
Mirco Weber ◽  
Julia Mrotzek ◽  
Christoph Gerhard ◽  
Stephan Wieneke ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Atmospheric Pressure ◽  
Nanoparticle Synthesis ◽  
Atmospheric Pressure Plasma ◽  
Spherical Particles ◽  
Synthesis Process ◽  
Plasma Exposure ◽  
Pressure Plasma ◽  
In Situ Investigation

In this publication, it is shown how to synthesize silver nanoparticles from silver cations out of aqueous solutions by the use of an atmospheric pressure plasma source. The use of an atmospheric pressure plasma leads to a very fast reduction of silver ions in extensive solvent volumes. In order to investigate the nanoparticle synthesis process, ultraviolet/visible (UV/VIS) absorption spectra were recorded in situ. By using transmission electron microscopy and by the analysis of UV/VIS spectra, the kinetics of silver nanoparticle formation by plasma influence can be seen in more detail. For example, there are two different sections visible in the synthesis during the plasma exposure process. The first section of the synthesis is characterized by a linear formation of small spherical particles of nearly constant size. The second section is predominated by saturation effects. Here, particle faults are increasingly formed, induced by changes in the particle shape and the fusion of those particles. The plasma exposure time, therefore, determines the shape and size distribution of the nanoparticles.

scholarly journals Chromium-modified cobalt molybdenum nitrides as catalysts for ammonia synthesis

2019 ◽  
Vol 17 (1) ◽  
pp. 127-131
Author(s):  
Paweł Adamski ◽  
Marlena Nadziejko ◽  
Agata Komorowska ◽  
Adam Sarnecki ◽  
Aleksander Albrecht ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Specific Surface ◽  
Surface Area ◽  
Chromium Content ◽  
Ammonia Synthesis ◽  
Chromium Concentration ◽  
Synthesis Process ◽  
Pure Cobalt ◽  
Molybdenum Nitrides ◽  
Chromium Compounds

AbstractThe influence of chromium compounds on the properties of cobalt molybdenum nitrides was studied. CoMoO4 obtained by precipitation from cobalt and molybdenum salts was modified by the addition of chromium(III) nitrate. A mixture of cobalt-molybdenum nitrides, Co2Mo3N and Co3Mo3N, was formed by ammonolysis of modified CoMoO4. The concentration of Co2Mo3N decreases with increasing chromium content. The specific surface area of cobalt molybdenum nitrides consisting of 2 wt% of Cr atoms increased by 50% in comparison to pure cobalt molybdenum nitrides. The catalytic activity of obtained catalysts in ammonia synthesis process decreases with rising of chromium concentration.

scholarly journals Non-thermal atmospheric pressure plasma as a powerful tool for the synthesis of rhenium-based nanostructures for the catalytic hydrogenation of 4-nitrophenol

RSC Advances ◽  
2021 ◽  
Vol 11 (61) ◽  
pp. 38596-38604
Author(s):  
Piotr Cyganowski ◽  
Dominik Terefinko ◽  
Piotr Jamroz ◽  
Pawel Pohl ◽  
Anna Dzimitrowicz
Keyword(s):  
Catalytic Activity ◽  
Catalytic Hydrogenation ◽  
Atmospheric Pressure ◽  
Atmospheric Pressure Plasma ◽  
Discharge System ◽  
Pressure Plasma ◽  
Unique Reaction

A unique reaction-discharge system was used for the production of Re-based nanoparticles (NPs) revealing enhanced catalytic activity.

scholarly journals The effect of iron nanocrystallites’ size in catalysts for ammonia synthesis on nitriding reaction and catalytic ammonia decomposition

2011 ◽  
Vol 9 (2) ◽  
pp. 240-244 ◽  
Author(s):  
Rafał Pelka ◽  
Karolina Kiełbasa ◽  
Walerian Arabczyk
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Atmospheric Pressure ◽  
Active Sites ◽  
Ammonia Synthesis ◽  
Iron Catalyst ◽  
Ammonia Decomposition ◽  
Mean Size ◽  
Catalytic Ammonia Decomposition

AbstractIron catalyst for ammonia synthesis of various mean sizes of iron nanocrystallites were nitrided with ammonia in a differential reactor equipped with systems that made it possible to conduct both thermogravimetric measurements and hydrogen concentration analyses in the reacting gas mixture. The nitriding process was investigated under atmospheric pressure at the temperature of 475°C. It was found that along with an increase of mean size of iron nanocrystallites, with a decrease of specific surface area of the samples, nitriding degree of solid samples increased. At the same time the rate of surface reaction of catalytic ammonia decomposition decreased. Along with an increase of the samples’ specific surface area an increase of the catalyst’s activity was observed. However, it was also observed that the concentration of active sites on the catalysts’ surface decreased along with an increase of specific surface area.

scholarly journals Synergistic Effects of Nonthermal Plasma and Disinfecting Agents against Dental Biofilms In Vitro

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Ina Koban ◽  
Marie Henrike Geisel ◽  
Birte Holtfreter ◽  
Lukasz Jablonowski ◽  
Nils-Olaf Hübner ◽  
...  
Keyword(s):  
Atmospheric Pressure ◽  
Synergistic Effects ◽  
Argon Plasma ◽  
Atmospheric Pressure Plasma ◽  
Nonthermal Plasma ◽  
Antimicrobial Effect ◽  
Dental Biofilm ◽  
Pressure Plasma ◽  
Cultivation Technique

Aim. Dental biofilms play a major role in the pathogenesis of many dental diseases. In this study, we evaluated the synergistic effect of atmospheric pressure plasma and different agents in dentistry on the reduction of biofilms. Methods and Results. We used monospecies (S. mutans) and multispecies dental biofilm models grown on titanium discs in vitro. After treatment with one of the agents, the biofilms were treated with plasma. Efficacy of treatment was determined by the number of colony forming units (CFU) and by live-dead staining. For S. mutans biofilms no colonies could be detected after treatment with NaOCl or H2O2. For multispecies biofilms the combination with plasma achieved a higher CFU reduction than each agent alone. We found an additive antimicrobial effect between argon plasma and agents irrespective of the treatment order with cultivation technique. For EDTA and octenidine, antimicrobial efficacy assessed by live-dead staining differed significantly between the two treatment orders (P<0.05). Conclusions. The effective treatment of dental biofilms on titanium discs with atmospheric pressure plasma could be increased by adding agents in vitro.

scholarly journals Ag Nanoparticles Stabilized on Cyclodextrin Polymer Decorated with Multi-Nitrogen Atom Containing Polymer: An Efficient Catalyst for the Synthesis of Xanthenes

Molecules ◽  
2020 ◽  
Vol 25 (2) ◽  
pp. 241 ◽  
Author(s):  
Samahe Sadjadi ◽  
Fatemeh Ghoreyshi Kahangi ◽  
Masoumeh Dorraj ◽  
Majid M. Heravi
Keyword(s):  
Catalytic Activity ◽  
Nitrogen Atom ◽  
Hybrid System ◽  
Ag Nanoparticles ◽  
Active Sites ◽  
Phase Transfer ◽  
High Catalytic Activity ◽  
Ag Nps ◽  
Efficient Catalyst ◽  
Cyclodextrin Polymer

In attempt to broaden the use of cyclodextrin polymer for catalytic purposes, a novel covalent hybrid system was prepared through growth of multi-nitrogen atom containing polymer (PMelamine) derived from reaction of ethylenediamine and 2,4,6-trichloro-1,3,5-triazine on the functionalized cyclodextrin polymer (CDNS). The resulting hybrid system was then utilized as a catalyst support for the immobilization of silver nanoparticles through using Cuscuta epithymum extract as a naturally-derived reducing agent. The catalytic activity of the catalyst, Ag@CDNS-N/PMelamine, for the synthesis of xanthenes through reaction of aldehydes and dimedone in aqueous media was examined. The results showed high catalytic activity and recyclability of the catalyst. It was believed that cyclodextrin in the backbone of the catalyst could act both as a capping agent for Ag nanoparticles and phase transfer agent to bring the hydrophobic substrates in the vicinity of the catalytic active sites and accelerate the reaction rate. Multi-nitrogen atoms on the polymer, on the other hand, could improve the Ag NPs anchoring and suppress their leaching.

Unveiling the Genesis of the High Catalytic Activity in Nickel Phthalocyanine for Electrochemical Ammonia Synthesis

2021 ◽  
Author(s):  
Shyamal Murmu ◽  
Sourav Paul ◽  
Samadhan Kapse ◽  
Ranjit Thapa ◽  
Santanu Chattopadhyay ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Active Sites ◽  
Ammonia Synthesis ◽  
Reduction Reaction ◽  
High Catalytic Activity ◽  
Nitrogen Reduction ◽  
Nickel Phthalocyanine ◽  
Bosch Process

Electrochemical ammonia synthesis by nitrogen reduction reaction (NRR) using economically efficient electrocatalyst can provide a substitute of Haber-Bosch process. However, identification of active sites responsible for the origination of catalytic...

Sign in / Sign up

Export Citation Format

Share Document