Nd-Fe-B: From sludge waste to powders via purification and modified Ca-reduction reaction process

Selective non-catalytic reduction (SNCR) is a denitration method in the high temperature area, and NH3 or urea is used for SNCR as reducing agents to react with NOX to produce N2 in the flue gas in the temperature ranged from 850°C to 1100°C. The SNCR deNOx technology has been well used in utility boiler, but compared with it, the lower denitration efficiency and the larger consumption of ammonia indicate a more complex process in cement pre-calciner. Unlike in utility boiler, the presence of high concentrations of cement raw materials may influence SNCR denitration reaction process in cement kilns. Therefore, studying the effect of CaO which occupy the major composition of cement raw material is very important in SNCR process. In this study the influence of CaO on the SNCR deNOx process was investigated by simulating SNCR reaction at temperature that ranges from 750°C to 1100°C with different normalized stoichiometric ratio. The experimental results demonstrate that the addition of CaO increases the optimum denitration temperature to 1100°C, but it has no effect on normalized stoichiometric ratio. In the whole reaction process NH3 not only restores NO to O2 but also reacts with O2 to NO. Since the adsorption of NH3 on CaO surface, in the temperature range of 750°C-850°C the addition of CaO promotes the reaction of NH3 and O2 and increases NOX concentration. However, in the temperature range of 850°C-1000°C it not only promotes NH3 oxidation but also inhibits the reduction reaction of NH3, thereby the denitration reaction is inhibited. In the temperature range of 1050°C-1100°C the denitration reaction is promoted due to the NH3 desorption from CaO surface.

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A theoretical study of atomically dispersed MN4/C (M = Fe or Mn) as a high-activity catalyst for the oxygen reduction reaction

Physical Chemistry Chemical Physics ◽

10.1039/d0cp04676k ◽

2020 ◽

Vol 22 (48) ◽

pp. 28297-28303

Author(s):

Hao Xu ◽

Dan Wang ◽

Peixia Yang ◽

Anmin Liu ◽

Ruopeng Li ◽

...

Keyword(s):

Oxygen Reduction Reaction ◽

Oxygen Reduction ◽

High Activity ◽

Active Site ◽

Theoretical Study ◽

Reduction Reaction ◽

Reaction Process ◽

Activity Catalyst

MN4 is the ORR active site of MN4/C, which can promote the reaction process to proceed through a four-electron pathway.

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Boosting selective nitrogen reduction to ammonia on electron-deficient copper nanoparticles

Nature Communications ◽

10.1038/s41467-019-12312-4 ◽

2019 ◽

Vol 10 (1) ◽

Cited By ~ 40

Author(s):

Yun-Xiao Lin ◽

Shi-Nan Zhang ◽

Zhong-Hua Xue ◽

Jun-Jun Zhang ◽

Hui Su ◽

...

Keyword(s):

Rational Design ◽

Reduction Reaction ◽

Reaction Process ◽

Cu Nanoparticles ◽

Ambient Conditions ◽

Depletion Effect ◽

Aqueous Conditions ◽

Electron Deficiency ◽

Near Future ◽

Insight Into

Abstract Production of ammonia is currently realized by the Haber–Bosch process, while electrochemical N2 fixation under ambient conditions is recognized as a promising green substitution in the near future. A lack of efficient electrocatalysts remains the primary hurdle for the initiation of potential electrocatalytic synthesis of ammonia. For cheaper metals, such as copper, limited progress has been made to date. In this work, we boost the N2 reduction reaction catalytic activity of Cu nanoparticles, which originally exhibited negligible N2 reduction reaction activity, via a local electron depletion effect. The electron-deficient Cu nanoparticles are brought in a Schottky rectifying contact with a polyimide support which retards the hydrogen evolution reaction process in basic electrolytes and facilitates the electrochemical N2 reduction reaction process under ambient aqueous conditions. This strategy of inducing electron deficiency provides new insight into the rational design of inexpensive N2 reduction reaction catalysts with high selectivity and activity.

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Effect of mixing on NO removal in the selective noncatalytic reduction reaction process

Journal of Material Cycles and Waste Management ◽

10.1007/s10163-010-0289-6 ◽

2010 ◽

Vol 12 (3) ◽

pp. 204-211

Author(s):

Gang-Woo Lee ◽

Byung-Hyun Shon ◽

Jong-Hyeon Jung ◽

Won-Joon Choi ◽

Kwang-Joong Oh

Keyword(s):

Reduction Reaction ◽

Reaction Process ◽

No Removal ◽

Selective Noncatalytic Reduction ◽

Noncatalytic Reduction

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Oxygen reduction reaction process of LaNi0.6Fe0.4O3− film – porous Ce0.9Gd0.1O1.95 heterostructure electrode

Solid State Ionics ◽

10.1016/j.ssi.2017.10.007 ◽

2017 ◽

Vol 312 ◽

pp. 80-87 ◽

Cited By ~ 4

Author(s):

R.A. Budiman ◽

S. Hashimoto ◽

T. Nakamura ◽

K. Yashiro ◽

K.D. Bagarinao ◽

...

Keyword(s):

Oxygen Reduction Reaction ◽

Oxygen Reduction ◽

Reduction Reaction ◽

Reaction Process

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A Pyridinic Fe-N4 Macrocycle Effectively Models the Active Sites in Fe/N-Doped Carbon Electrocatalysts

10.26434/chemrxiv.10008545.v2 ◽

2020 ◽

Author(s):

Travis Marshall-Roth ◽

Nicole J. Libretto ◽

Alexandra T. Wrobel ◽

Kevin Anderton ◽

Nathan D. Ricke ◽

...

Keyword(s):

Oxygen Reduction ◽

Active Sites ◽

Catalytic Properties ◽

Reduction Reaction ◽

Iron Phthalocyanine ◽

Electrochemical Studies ◽

Onset Potential ◽

Nitrogen Doped Carbon ◽

Iron Active Sites

Iron- and nitrogen-doped carbon (Fe-N-C) materials are leading candidates to replace platinum in fuel cells, but their active site structures are poorly understood. A leading postulate is that iron active sites in this class of materials exist in an Fe-N4 pyridinic ligation environment. Yet, molecular Fe-based catalysts for the oxygen reduction reaction (ORR) generally feature pyrrolic coordination and pyridinic Fe-N4 catalysts are, to the best of our knowledge, non-existent. We report the synthesis and characterization of a molecular pyridinic hexaazacyclophane macrocycle, (phen2N2)Fe, and compare its spectroscopic, electrochemical, and catalytic properties for oxygen reduction to a prototypical Fe-N-C material, as well as iron phthalocyanine, (Pc)Fe, and iron octaethylporphyrin, (OEP)Fe, prototypical pyrrolic iron macrocycles. N 1s XPS signatures for coordinated N atoms in (phen2N2)Fe are positively shifted relative to (Pc)Fe and (OEP)Fe, and overlay with those of Fe-N-C. Likewise, spectroscopic XAS signatures of (phen2N2)Fe are distinct from those of both (Pc)Fe and (OEP)Fe, and are remarkably similar to those of Fe-N-C with compressed Fe–N bond lengths of 1.97 Å in (phen2N2)Fe that are close to the average 1.94 Å length in Fe-N-C. Electrochemical studies establish that both (Pc)Fe and (phen2N2)Fe have relatively high Fe(III/II) potentials at ~0.6 V, ~300 mV positive of (OEP)Fe. The ORR onset potential is found to directly correlate with the Fe(III/II) potential leading to a ~300 mV positive shift in the onset of ORR for (Pc)Fe and (phen2N2)Fe relative to (OEP)Fe. Consequently, the ORR onset for (phen2N2)Fe and (Pc)Fe is within 150 mV of Fe-N-C. Unlike (OEP)Fe and (Pc)Fe, (phen2N2)Fe displays excellent selectivity for 4-electron ORR with <4% maximum H2O2 production, comparable to Fe-N-C materials. The aggregate spectroscopic and electrochemical data establish (phen2N2)Fe as a pyridinic iron macrocycle that effectively models Fe-N-C active sites, thereby providing a rich molecular platform for understanding this important class of catalytic materials.

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Promoting Nitrogen Electroreduction to Ammonia with Bismuth Nanocrystals and Potassium Cations in Water

10.26434/chemrxiv.11768814.v1 ◽

2020 ◽

Cited By ~ 1

Author(s):

Jaecheol Choi ◽

Hoang-Long Du ◽

Manjunath Chatti ◽

Bryan H. R. Suryanto ◽

Alexandr Simonov ◽

...

Keyword(s):

Electrocatalytic Activity ◽

Aqueous Electrolyte ◽

Electrolyte Solutions ◽

Reduction Reaction ◽

Nitrogen Reduction ◽

Aqueous Electrolyte Solutions

We demonstrate that bismuth exhibits no measurable electrocatalytic activity for the nitrogen reduction reaction to ammonia in aqueous electrolyte solutions, contrary to several recent reports on the highly impressive rates of Bi-catalysed electrosynthesis of NH3 from N2.

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Graphene Supported Tungsten Carbide as Catalyst for Electrochemical Reduction of CO2

10.26434/chemrxiv.8280986 ◽

2019 ◽

Author(s):

Sahithi Ananthaneni ◽

Rees Rankin

Keyword(s):

Tungsten Carbide ◽

Electrochemical Reduction ◽

Low Cost ◽

Co2 Reduction ◽

Platinum Group Metal ◽

Reduction Reaction ◽

Metal Carbides ◽

Depth Study ◽

Reduction Of Co2 ◽

Co2 Reduction Reaction

<div>Electrochemical reduction of CO2 to useful chemical and fuels in an energy efficient way is currently an expensive and inefficient process. Recently, low-cost transition metal-carbides (TMCs) are proven to exhibit similar electronic structure similarities to Platinum-Group-Metal (PGM) catalysts and hence can be good substitutes for some important reduction reactions. In this work, we test graphenesupported WC (Tungsten Carbide) nanocluster as an electrocatalyst for the CO2 reduction reaction. Specifically, we perform DFT studies to understand various possible reaction mechanisms and determine the lowest thermodynamic energy landscape of CO2 reduction to various products such as CO, HCOOH, CH3OH, and CH4. This in-depth study of reaction energetics could lead to improvements and develop more efficient electrocatalysts for CO2 reduction. </div>

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