Effects of SO2 on Standard and Fast SCR over CeWO : A Quantitative Study of the Reaction Pathway and Active Sites

2021 ◽  
pp. 120784
Author(s):  
Yanlong Huo ◽  
Kuo Liu ◽  
Jingjing Liu ◽  
Hong He
Keyword(s):  
Quantitative Study ◽  
Active Sites ◽  
Reaction Pathway ◽  
Fast Scr

The effects of H2O on a vanadium-based catalyst for NH3-SCR at low temperatures: a quantitative study of the reaction pathway and active sites

2019 ◽  
Vol 9 (20) ◽  
pp. 5593-5604 ◽  
Author(s):  
Kuo Liu ◽  
Zidi Yan ◽  
Hong He ◽  
Qingcai Feng ◽  
Wenpo Shan
Keyword(s):  
Quantitative Study ◽  
Active Site ◽  
Low Temperatures ◽  
Active Sites ◽  
Reaction Pathway ◽  
Site Distribution ◽  
Nh3 Scr

The effects of H2O on the adsorption amounts of NO, NO2, and NH3, NH3-SCR reaction pathway and active site distribution over V2O5/WO3–TiO2 at low temperatures were quantitatively studied by the TRM and TPSR.

Catalytic Resonance Theory: Parallel Reaction Pathway Control

2019 ◽  
Author(s):  
M. Alexander Ardagh ◽  
Manish Shetty ◽  
Anatoliy Kuznetsov ◽  
Qi Zhang ◽  
Phillip Christopher ◽  
...  
Keyword(s):  
Chemical Reactions ◽  
Active Site ◽  
Active Sites ◽  
Reaction Pathway ◽  
Control Strategies ◽  
Oscillation Amplitude ◽  
Catalytic Performance ◽  
Parallel Reaction ◽  
Resonance Theory ◽  
Static Conditions

Catalytic enhancement of chemical reactions via heterogeneous materials occurs through stabilization of transition states at designed active sites, but dramatically greater rate acceleration on that same active site is achieved when the surface intermediates oscillate in binding energy. The applied oscillation amplitude and frequency can accelerate reactions orders of magnitude above the catalytic rates of static systems, provided the active site dynamics are tuned to the natural frequencies of the surface chemistry. In this work, differences in the characteristics of parallel reactions are exploited via selective application of active site dynamics (0 < ΔU < 1.0 eV amplitude, 10<sup>-6</sup> < f < 10<sup>4</sup> Hz frequency) to control the extent of competing reactions occurring on the shared catalytic surface. Simulation of multiple parallel reaction systems with broad range of variation in chemical parameters revealed that parallel chemistries are highly tunable in selectivity between either pure product, even when specific products are not selectively produced under static conditions. Two mechanisms leading to dynamic selectivity control were identified: (i) surface thermodynamic control of one product species under strong binding conditions, or (ii) catalytic resonance of the kinetics of one reaction over the other. These dynamic parallel pathway control strategies applied to a host of chemical conditions indicate significant potential for improving the catalytic performance of many important industrial chemical reactions beyond their existing static performance.

scholarly journals Spin-sate reconfiguration induced by alternating magnetic field for efficient oxygen evolution reaction

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Gang Zhou ◽  
Peifang Wang ◽  
Hao Li ◽  
Bin Hu ◽  
Yan Sun ◽  
...  
Keyword(s):  
Reaction Kinetics ◽  
Oxygen Evolution ◽  
Oxygen Evolution Reaction ◽  
Active Sites ◽  
Reaction Pathway ◽  
Low Cost ◽  
Orbital Interaction ◽  
New Paradigm ◽  
Metal Organic ◽  
Energy Conversion Devices

AbstractOxygen evolution reaction (OER) plays a determining role in electrochemical energy conversion devices, but challenges remain due to the lack of effective low-cost electrocatalysts and insufficient understanding about sluggish reaction kinetics. Distinguish from complex nano-structuring, this work focuses on the spin-related charge transfer and orbital interaction between catalysts and intermediates to accelerate catalytic reaction kinetics. Herein, we propose a simple magnetic-stimulation approach to rearrange spin electron occupation in noble-metal-free metal-organic frameworks (MOFs) with a feature of thermal-differentiated superlattice, in which the localized magnetic heating in periodic spatial distribution makes the spin flip occur at particular active sites, demonstrating a spin-dependent reaction pathway. As a result, the spin-rearranged Co0.8Mn0.2 MOF displays mass activities of 3514.7 A gmetal−1 with an overpotential of ~0.27 V, which is 21.1 times that of pristine MOF. Our findings provide a new paradigm for designing spin electrocatalysis and steering reaction kinetics.

Efficient N2 Reduction with VS2 Electrocatalyst: Identifying the Active Sites and Unraveling the Reaction Pathway

2021 ◽  
Author(s):  
Liang Zhao ◽  
Rui Zhao ◽  
Yixiang Zhou ◽  
Xiaoxuan Wang ◽  
Xinyue Chi ◽  
...  
Keyword(s):  
Active Sites ◽  
Reaction Pathway ◽  
Reduction Reaction ◽  
Sustainable Production ◽  
Nitrogen Reduction

Electrochemical nitrogen reduction reaction (NRR) is an effective method for sustainable production of NH3. However, a robust NRR electrocatalyst is predominantly required in order to active the inert N2 molecule....

scholarly journals Platinum–copper single atom alloy catalysts with high performance towards glycerol hydrogenolysis

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Xi Zhang ◽  
Guoqing Cui ◽  
Haisong Feng ◽  
Lifang Chen ◽  
Hui Wang ◽  
...  
Keyword(s):  
Active Sites ◽  
High Performance ◽  
Reaction Pathway ◽  
Theoretical Calculations ◽  
Experimental Studies ◽  
Value Added ◽  
Catalytic Performance ◽  
Single Atom ◽  
Glycerol Hydrogenolysis ◽  
Single Atom Alloy

AbstractSelective hydrogenolysis of biomass-derived glycerol to propanediol is an important reaction to produce high value-added chemicals but remains a big challenge. Herein we report a PtCu single atom alloy (SAA) catalyst with single Pt atom dispersed on Cu nanoclusters, which exhibits dramatically boosted catalytic performance (yield: 98.8%) towards glycerol hydrogenolysis to 1,2-propanediol. Remarkably, the turnover frequency reaches up to 2.6 × 103 molglycerol·molPtCu–SAA−1·h−1, which is to our knowledge the largest value among reported heterogeneous metal catalysts. Both in situ experimental studies and theoretical calculations verify interface sites of PtCu–SAA serve as intrinsic active sites, in which the single Pt atom facilitates the breakage of central C–H bond whilst the terminal C–O bond undergoes dissociation adsorption on adjacent Cu atom. This interfacial synergistic catalysis based on PtCu–SAA changes the reaction pathway with a decreased activation energy, which can be extended to other noble metal alloy systems.

scholarly journals Methanol conversion on borocarbonitride catalysts: Identification and quantification of active sites

2020 ◽  
Vol 6 (26) ◽  
pp. eaba5778 ◽  
Author(s):  
Xuefei Zhang ◽  
Pengqiang Yan ◽  
Junkang Xu ◽  
Fan Li ◽  
Felix Herold ◽  
...  
Keyword(s):  
Active Sites ◽  
Density Functional ◽  
Catalytic Mechanism ◽  
Reaction Pathway ◽  
Methanol Conversion ◽  
Kinetic Measurements ◽  
Catalytic Systems ◽  
X Ray Absorption ◽  
Further Development

Borocarbonitrides (BCNs) have emerged as highly selective catalysts for the oxidative dehydrogenation (ODH) reaction. However, there is a lack of in-depth understanding of the catalytic mechanism over BCN catalysts due to the complexity of the surface oxygen functional groups. Here, BCN nanotubes with multiple active sites are synthesized for oxygen-assisted methanol conversion reaction. The catalyst shows a notable activity improvement for methanol conversion (29%) with excellent selectivity to formaldehyde (54%). Kinetic measurements indicate that carboxylic acid groups on BCN are responsible for the formation of dimethyl ether, while the redox catalysis to formaldehyde occurs on both ketonic carbonyl and boron hydroxyl (B─OH) sites. The ODH reaction pathway on the B─OH site is further revealed by in situ infrared, x-ray absorption spectra, and density functional theory. The present work provides physical-chemical insights into the functional mechanism of BCN catalysts, paving the way for further development of the underexplored nonmetallic catalytic systems.

Experimental and Computational Interrogation of Fast SCR Mechanism and Active Sites on H-Form SSZ-13

ACS Catalysis ◽  
2017 ◽  
Vol 7 (8) ◽  
pp. 5087-5096 ◽  
Author(s):  
Sichi Li ◽  
Yang Zheng ◽  
Feng Gao ◽  
Janos Szanyi ◽  
William F. Schneider
Keyword(s):  
Active Sites ◽  
Fast Scr

scholarly journals Efficient upgrading of CO to C3 fuel using asymmetric C-C coupling active sites

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Xue Wang ◽  
Ziyun Wang ◽  
Tao-Tao Zhuang ◽  
Cao-Thang Dinh ◽  
Jun Li ◽  
...  
Keyword(s):  
Energy Density ◽  
Active Sites ◽  
Reaction Pathway ◽  
Energy Conversion Efficiency ◽  
High Energy ◽  
High Energy Density ◽  
Renewable Electricity ◽  
Half Cell ◽  
Asymmetric Reaction ◽  
Faradaic Efficiency

AbstractThe electroreduction of C1 feedgas to high-energy-density fuels provides an attractive avenue to the storage of renewable electricity. Much progress has been made to improve selectivity to C1 and C2 products, however, the selectivity to desirable high-energy-density C3 products remains relatively low. We reason that C3 electrosynthesis relies on a higher-order reaction pathway that requires the formation of multiple carbon-carbon (C-C) bonds, and thus pursue a strategy explicitly designed to couple C2 with C1 intermediates. We develop an approach wherein neighboring copper atoms having distinct electronic structures interact with two adsorbates to catalyze an asymmetric reaction. We achieve a record n-propanol Faradaic efficiency (FE) of (33 ± 1)% with a conversion rate of (4.5 ± 0.1) mA cm−2, and a record n-propanol cathodic energy conversion efficiency (EEcathodic half-cell) of 21%. The FE and EEcathodic half-cell represent a 1.3× improvement relative to previously-published CO-to-n-propanol electroreduction reports.

scholarly journals Two Distinct Modes of Processive Kinesin Movement in Mixtures of ATP and AMP-PNP

2007 ◽  
Vol 130 (5) ◽  
pp. 445-455 ◽  
Author(s):  
Radhika Subramanian ◽  
Jeff Gelles
Keyword(s):  
Active Sites ◽  
Atp Hydrolysis ◽  
Reaction Pathway ◽  
Duty Ratio ◽  
Tight Coupling ◽  
Functional Mechanism ◽  
Motor Enzymes

An enzyme is frequently conceived of as having a single functional mechanism. This is particularly true for motor enzymes, where the necessity for tight coupling of mechanical and chemical cycles imposes rigid constraints on the reaction pathway. In mixtures of substrate (ATP) and an inhibitor (adenosine 5′-(β,γ-imido)triphosphate or AMP-PNP), single kinesin molecules move on microtubules in two distinct types of multiple-turnover “runs” that differ in their susceptibility to inhibition. Longer (less susceptible) runs are consistent with movement driven by the alternating-sites mechanism previously proposed for uninhibited kinesin. In contrast, kinesin molecules in shorter runs step with AMP-PNP continuously bound to one of the two active sites of the enzyme. Thus, in this mixture of substrate and inhibitor, kinesin can function as a motor enzyme using either of two distinct mechanisms. In one of these, the enzyme can accomplish high-duty-ratio processive movement without alternating-sites ATP hydrolysis.

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