scholarly journals Al2O3-Supported Transition Metals for Plasma-Catalytic NH3 Synthesis in a DBD Plasma: Metal Activity and Insights into Mechanisms

Catalysts ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1230
Author(s):  
Yury Gorbanev ◽  
Yannick Engelmann ◽  
Kevin van’t Veer ◽  
Evgenii Vlasov ◽  
Callie Ndayirinde ◽  
...  
Keyword(s):  
Catalytic Mechanism ◽  
Metal Catalyst ◽  
Potential Contribution ◽  
Plasma Catalysis ◽  
Dbd Plasma ◽  
Microkinetic Model ◽  
Industrial Energy ◽  
Cu Catalysts ◽  
Radical Adsorption ◽  
Good Agreement

N2 fixation into NH3 is one of the main processes in the chemical industry. Plasma catalysis is among the environmentally friendly alternatives to the industrial energy-intensive Haber-Bosch process. However, many questions remain open, such as the applicability of the conventional catalytic knowledge to plasma. In this work, we studied the performance of Al2O3-supported Fe, Ru, Co and Cu catalysts in plasma-catalytic NH3 synthesis in a DBD reactor. We investigated the effects of different active metals, and different ratios of the feed gas components, on the concentration and production rate of NH3, and the energy consumption of the plasma system. The results show that the trend of the metal activity (common for thermal catalysis) does not appear in the case of plasma catalysis: here, all metals exhibited similar performance. These findings are in good agreement with our recently published microkinetic model. This highlights the virtual independence of NH3 production on the metal catalyst material, thus validating the model and indicating the potential contribution of radical adsorption and Eley-Rideal reactions to the plasma-catalytic mechanism of NH3 synthesis.

Removal of sulfur dioxide from air using a packed-bed DBD plasma reactor (PBR) and in-plasma catalysis (IPC) hybrid system

2021 ◽  
Author(s):  
Niloofar Damyar ◽  
Ali Khavanin ◽  
Ahmad Jonidi Jafari ◽  
Hassan Asilian Mahabadi ◽  
Ramazan Mirzaei ◽  
...  
Keyword(s):  
Sulfur Dioxide ◽  
Hybrid System ◽  
Plasma Reactor ◽  
Packed Bed ◽  
Plasma Catalysis ◽  
Dbd Plasma

scholarly journals K-Promoted Ni-Based Catalysts for Gas-Phase CO2 Conversion: Catalysts Design and Process Modelling Validation

2021 ◽  
Vol 9 ◽  
Author(s):  
J. Gandara-Loe ◽  
E. Portillo ◽  
J. A. Odriozola ◽  
T. R. Reina ◽  
L. Pastor-Pérez
Keyword(s):  
Coke Formation ◽  
Surface Characteristics ◽  
Process Modelling ◽  
Metal Catalyst ◽  
Reaction Conditions ◽  
Reverse Water Gas Shift ◽  
Rwgs Reaction ◽  
Lower Temperature ◽  
Water Gas ◽  
Good Agreement

The exponential growth of greenhouse gas emissions and their associated climate change problems have motivated the development of strategies to reduce CO2 levels via CO2 capture and conversion. Reverse water gas shift (RWGS) reaction has been targeted as a promising pathway to convert CO2 into syngas which is the primary reactive in several reactions to obtain high-value chemicals. Among the different catalysts reported for RWGS, the nickel-based catalyst has been proposed as an alternative to the expensive noble metal catalyst. However, Ni-based catalysts tend to be less active in RWGS reaction conditions due to preference to CO2 methanation reaction and to the sintering and coke formation. Due to this, the aim of this work is to study the effect of the potassium (K) in Ni/CeO2 catalyst seeking the optimal catalyst for low-temperature RWGS reaction. We synthesised Ni-based catalyst with different amounts of K:Ni ratio (0.5:10, 1:10, and 2:10) and fully characterised using different physicochemical techniques where was observed the modification on the surface characteristics as a function of the amount of K. Furthermore, it was observed an improvement in the CO selectivity at a lower temperature as a result of the K-Ni-support interactions but also a decrease on the CO2 conversion. The 1K catalyst presented the best compromise between CO2 conversion, suppression of CO2 methanation and enhancing CO selectivity. Finally, the experimental results were contrasted with the trends obtained from the thermodynamics process modelling observing that the result follows in good agreement with the modelling trends giving evidence of the promising behaviour of the designed catalysts in CO2 high-scale units.

scholarly journals Progress and Challenges of Mercury-Free Catalysis for Acetylene Hydrochlorination

Catalysts ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1218
Author(s):  
Yanxia Liu ◽  
Lin Zhao ◽  
Yagang Zhang ◽  
Letao Zhang ◽  
Xingjie Zan
Keyword(s):  
Noble Metal ◽  
Chemical Industry ◽  
Catalytic Mechanism ◽  
Catalyst Design ◽  
Research Progress ◽  
Metal Catalyst ◽  
Noble Metal Catalyst ◽  
Acetylene Hydrochlorination ◽  
Design And Synthesis ◽  
Toxic Pollutant

Activated carbon-supported HgCl2 catalyst has been used widely in acetylene hydrochlorination in the chlor-alkali chemical industry. However, HgCl2 is an extremely toxic pollutant. It is not only harmful to human health but also pollutes the environment. Therefore, the design and synthesis of mercury-free and environmentally benign catalysts with high activity has become an urgent need for vinyl chloride monomer (VCM) production. This review summarizes research progress on the design and development of mercury-free catalysts for acetylene hydrochlorination. Three types of catalysts for acetylene hydrochlorination in the chlor-alkali chemical industry are discussed. These catalysts are a noble metal catalyst, non-noble metal catalyst, and non-metallic catalyst. This review serves as a guide in terms of the catalyst design, properties, and catalytic mechanism of mercury-free catalyst for the acetylene hydrochlorination of VCM. The key problems and issues are discussed, and future trends are envisioned.

scholarly journals Isotope Labelling for Reaction Mechanism Analysis in DBD Plasma Processes

Catalysts ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 45 ◽  
Author(s):  
Paula Navascués ◽  
Jose M. Obrero-Pérez ◽  
José Cotrino ◽  
Agustín R. González-Elipe ◽  
Ana Gómez-Ramírez
Keyword(s):  
Energy Efficiency ◽  
Practical Implementation ◽  
Operating Pressure ◽  
Mechanism Analysis ◽  
Plasma Catalysis ◽  
Gas Phase Reactions ◽  
Dbd Plasma ◽  
Isotope Labelling ◽  
Gas Molecules ◽  
Selectivity Control

Dielectric barrier discharge (DBD) plasmas and plasma catalysis are becoming an alternative procedure to activate various gas phase reactions. A low-temperature and normal operating pressure are the main advantages of these processes, but a limited energy efficiency and little selectivity control hinder their practical implementation. In this work, we propose the use of isotope labelling to retrieve information about the intermediate reactions that may intervene during the DBD processes contributing to a decrease in their energy efficiency. The results are shown for the wet reforming reaction of methane, using D2O instead of H2O as reactant, and for the ammonia synthesis, using NH3/D2/N2 mixtures. In the two cases, it was found that a significant amount of outlet gas molecules, either reactants or products, have deuterium in their structure (e.g., HD for hydrogen, CDxHy for methane, or NDxHy for ammonia). From the analysis of the evolution of the labelled molecules as a function of power, useful information has been obtained about the exchange events of H by D atoms (or vice versa) between the plasma intermediate species. An evaluation of the number of these events revealed a significant progression with the plasma power, a tendency that is recognized to be detrimental for the energy efficiency of reactant to product transformation. The labelling technique is proposed as a useful approach for the analysis of plasma reaction mechanisms.

A Study of Point Defects and Cause of Nonstoichiometry in InSb Nanowires

2011 ◽  
Vol 1302 ◽  
Author(s):  
U. Philipose ◽  
Gopal Sapkota ◽  
Pradeep Gali ◽  
Prathyusha Nukala
Keyword(s):  
Point Defects ◽  
Growth Temperature ◽  
Defect Formation ◽  
Growth Parameters ◽  
Chemical Vapor ◽  
Metal Catalyst ◽  
Vapor Pressures ◽  
Experimental Findings ◽  
Good Agreement ◽  
Insb Nanowires

ABSTRACTSynthesis of InSb nanowires using chemical vapor deposition (CVD) is technically challenging due to the tuning of III-V vapor pressures. Growth parameters such as the choice of the metal catalyst, growth temperature and vapor pressure of constituents affect the morphology and stoichiometry of InSb nanowires. By controlling the growth temperature, it was possible to grow either stoichiometric InSb nanowires or In nanowires that contained no Sb within detectable limits. We present a simple model to show that the occurrence of native point defects in InSb is influenced by the growth kinetics and by the thermodynamics of defect formation. Results from this model are in good agreement with our experimental findings of the evidence of point defects in these nanowires.

scholarly journals Supported Cu/W/Mo/Ni—Liquid Metal Catalyst with Core-Shell Structure for Photocatalytic Degradation

Catalysts ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1419
Author(s):  
Shuting Liang ◽  
Chaowei Wang ◽  
Fengjiao Li ◽  
Gang Song
Keyword(s):  
Liquid Metal ◽  
Catalytic Mechanism ◽  
Solid Phase ◽  
Liquid Metals ◽  
Metal Species ◽  
Metal Catalyst ◽  
Core Shell ◽  
Metal Metal ◽  
Catalytic Material ◽  
Shell Composite

Room-temperature liquid metal is a very ideal material for the design of catalytic materials. At low temperatures, the liquid metal enters the liquid state. It provides an opportunity to utilize the liquid phase in the catalysis, which is far superior to the traditional solid-phase catalyst. Aiming at the low performance and narrow application scope of the existing single-phase liquid metal catalyst, this paper proposed a type of liquid metal/metal oxide core-shell composite multi-metal catalyst. The Ga2O3 core-shell heterostructure was formed by chemical modification of liquid metals with different nano metals Cu/W/Mo/Ni, and it was applied to photocatalytic degrading organic contaminated raw liquor. The effects of different metal species on the rate of catalytic degradation were explored. The selectivity and stability of the LM/MO core-shell composite catalytic material were clarified, and it was found that the Ni-LM catalyst could degrade methylene blue and Congo red by 84% and 74%, respectively. The catalytic mechanism and charge transfer mechanism were revealed by combining the optical band gap value. Finally, we provided a theoretical basis for the further development of liquid metal photocatalytic materials in the field of new energy environments.

scholarly journals Catalytic Mechanism of Pd Adsorption on S-Terminated GaAs(001)-(2 × 6) Surface

2013 ◽  
Vol 2013 ◽  
pp. 1-4
Author(s):  
Deng-feng Li ◽  
Zhi-cheng Guo ◽  
Bo-Lin Li ◽  
Ming Luo
Keyword(s):  
Electronic Properties ◽  
Density Of States ◽  
Heck Reaction ◽  
Catalytic Mechanism ◽  
First Principle ◽  
Structural And Electronic Properties ◽  
Good Agreement

Structural and electronic properties of Pd adsorption on clean and S-terminated GaAs(001)-(2 × 6) surfaces are studied using first-principle simulations. Our calculations show that the Pd atom prefers to occupy the HH3 site. The Pd atom is lower than the S atom with 0.15 Å. The density of states analysis confirms that S–Ga bond plays an important role in Heck reaction. We also find that the Pd catalysis activity for Pd adsorption on clean GaAs(001)-(2 × 6) surface is weak while it is enhanced when the Pd atom is adsorbed on the S-terminated GaAs(001)-(2 × 6) surface, which is in good agreement with the experiments.

Oscillator Strength Measurements in the Vacuum-Ultraviolet by the Emission Method

1988 ◽  
Vol 102 ◽  
pp. 353-356
Author(s):  
C. Goldbach ◽  
G. Nollez
Keyword(s):  
Oscillator Strength ◽  
Vacuum Ultraviolet ◽  
Oscillator Strengths ◽  
Emission Method ◽  
Absolute Scale ◽  
Good Agreement

AbstractThe principles and the realization of an experiment devoted to oscillator strength measurements in the vacuum-ultraviolet by the emission method are briefly presented. The results obtained for the strong multiplets of neutral nitrogen and carbon in the 1200-2000 Å range yield an absolute scale of oscillator strengths in good agreement with the most recent calculations.

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