Post-plasma catalysis: charge effect on product selectivity in conversion of methane and nitrogen plasma to ethylene and ammonia

Tiwari, Sarojini; Ibrahim, Saleh Ahmat; Robinson, Brandon; Brown, Sean; Wang, Qiang; Che, Fanglin; Hu, Jianli

doi:10.1039/d2cy02077g

Cited by 6 publications

(10 citation statements)

References 83 publications

(119 reference statements)

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“…Electrostatic interactions rely on particle chemistry, geometry, and plasma properties; while a full analysis is impossible, the review by Neyts and our recent work by Tiwari et al. support our observations. , The charging effect can both increase and decrease the reaction rates of interest …”

Section: Resultssupporting

confidence: 71%

Ambient Carbon-Neutral Ammonia Generation via a Cyclic Microwave Plasma Process

Brown

Ibrahim

Robinson

et al. 2023

ACS Appl. Mater. Interfaces

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A novel reactor methodology was developed for chemical looping ammonia synthesis processes using microwave plasma for pre-activation of the stable dinitrogen molecule before reaching the catalyst surface. Microwave plasma-enhanced reactions benefit from higher production of activated species, modularity, quick startup, and lower voltage input than competing plasma-catalysis technologies. Simple, economical, and environmentally benign metallic iron catalysts were used in a cyclical atmospheric pressure synthesis of ammonia. Rates of up to 420.9 μmol min–1 g–1 were observed under mild nitriding conditions. Reaction studies showed that both surface-mediated and bulk-mediated reaction domains were found to exist depending on the time under plasma treatment. The associated density functional theory (DFT) calculations indicated that a higher temperature promoted more nitrogen species in the bulk of iron catalysts but the equilibrium limited the nitrogen converion to ammonia, and vice versa. Generation of vibrationally active N2 and, N2 + ions is associated with lower bulk nitridation temperatures and increased nitrogen contents versus thermal-only systems. Additionally, the kinetics of other transition metal chemical looping ammonia synthesis catalysts (Mn and CoMo) were evaluated by high-resolution time-on-stream kinetic analysis and optical plasma characterization. This study sheds new light on phenomena arising in transient nitrogen storage, kinetics, effect of plasma treatment, apparent activation energies, and rate-limiting reaction steps.

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Section: Resultssupporting

confidence: 71%

Ambient Carbon-Neutral Ammonia Generation via a Cyclic Microwave Plasma Process

Brown

Ibrahim

Robinson

et al. 2023

ACS Appl. Mater. Interfaces

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“…[21] Recent results were published by Tiwari et al 2023, and summarized below (Figure 2). [22] When plasma is coupled with a catalyst, AgPd/CeO 2 , the selectivities of the reactions are shifted. [22] Additionally, coflowing with N 2 was found to prevent the overhydrogenation of ethylene into other products by forming ammonia (Figure 2).…”

Section: Mw-plasma Catalysismentioning

confidence: 99%

“…[22] When plasma is coupled with a catalyst, AgPd/CeO 2 , the selectivities of the reactions are shifted. [22] Additionally, coflowing with N 2 was found to prevent the overhydrogenation of ethylene into other products by forming ammonia (Figure 2). [22] These results suggest that surface charging explains the catalytic reactions observed over the AgPd catalyst by shifting reaction energies which leads to differing selectivities, and more broadly some of the different metal performances observed under plasma-catalysis.…”

Section: Mw-plasma Catalysismentioning

confidence: 99%

Post‐microwave plasma catalysis: Current developments and future implications

Brown,

Tiwari,

2024

Plasma Processes & Polymers

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Post‐microwave plasma catalysis combines plasma preactivation of the gas phase followed by a fixed bed catalyst. This process has the potential to be energy efficient, modular, versatile and to generate high numbers of active species compared with other plasma generation technologies. Specific applications of these post‐microwave plasma systems include the dissociation and activation of stable molecules and the modification of catalyst materials. This concept article will address the current findings in microwave plasma catalysis research and propose future questions that need to be addressed to further develop the technology.

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“…[51] Furthermore, catalysts may modify the reaction pathways and allow specific types of reactions to occur, thereby improving the selectivity of the desired products. [52] Typically, catalysts that exhibit higher activity have strong binding energies to nitrogen atoms. However, when such a catalyst is used, the products tend to remain adsorbed on the active sites, which somehow lowers the reaction rates.…”

Section: Synergistic Effects With Catalystsmentioning

confidence: 99%

“…The presence of active sites on the catalyst surface provides a favorable environment for these reactions, lowering the dissociation energy and promoting interactions between reactant molecules [51] . Furthermore, catalysts may modify the reaction pathways and allow specific types of reactions to occur, thereby improving the selectivity of the desired products [52] …”

Section: Plasma‐assisted Synthesis Of Nh3 From N2 and H2mentioning

confidence: 99%

Plasma‐Assisted Sustainable Nitrogen‐to‐Ammonia Fixation: Mixed‐phase, Synergistic Processes and Mechanisms

Qu,

Zhou,

Sun

et al. 2023

ChemSusChem

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Ammonia plays a crucial role in industry and agriculture worldwide, but traditional industrial ammonia production methods are energy‐intensive and negatively impact the environment. Ammonia synthesis using low‐temperature plasma technology has gained traction in the pursuit of environment‐benign and cost‐effective methods for producing green ammonia. This Review discusses the recent advances in low‐temperature plasma‐assisted ammonia synthesis, focusing on three main routes: N2+H2 plasma‐only, N2+H2O plasma‐only, and plasma coupled with other technologies. The reaction pathways involved in the plasma‐assisted ammonia synthesis, as well as the process parameters, including the optimum catalyst types and discharge schemes, are examined. Building upon the current research status, the challenges and research opportunities in the plasma‐assisted ammonia synthesis processes are outlined. The article concludes with the outlook for the future development of the plasma‐assisted ammonia synthesis technology in real‐life industrial applications.

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Post-plasma catalysis: charge effect on product selectivity in conversion of methane and nitrogen plasma to ethylene and ammonia

Abstract: Microwave-enhanced methane and nitrogen plasma is known to produce dense and highly active plasma species at atmospheric pressure. The main challenge in simultaneous production of ethylene and ammonia under plasma...

Cited by 6 publications

References 83 publications

Ambient Carbon-Neutral Ammonia Generation via a Cyclic Microwave Plasma Process

Ambient Carbon-Neutral Ammonia Generation via a Cyclic Microwave Plasma Process

Post‐microwave plasma catalysis: Current developments and future implications

Plasma‐Assisted Sustainable Nitrogen‐to‐Ammonia Fixation: Mixed‐phase, Synergistic Processes and Mechanisms

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