Plasma-catalyst modeling for materials selection: challenges and opportunities in nitrogen oxidation

Ma, Hanyu; Schneider, William F.

doi:10.1088/1361-6463/ac1bd1

Cited by 8 publications

(8 citation statements)

References 55 publications

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“…25% of gas phase entropies were assumed to be lost in adsorption reactions. The entropy assumptions impact the absolute values of predicted microkinetic rates but have much weaker influence on relative rates across materials or versus temperatures . For a reaction involving only surface species, Δ S TS ° is assumed to be zero.…”

Section: Experimental Sectionmentioning

confidence: 99%

“…The entropy assumptions impact the absolute values of predicted microkinetic rates but have much weaker influence on relative rates across materials or versus temperatures. 38 involving only surface species, ΔS TS °is assumed to be zero. This simplification has negligible influence on microkinetic rates versus models parametrized with a harmonic oscillator model.…”

Section: ■ Introductionmentioning

confidence: 99%

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Plasma-Catalyst Reactivity Control of Surface Nitrogen Species through Plasma-Temperature-Programmed Hydrogenation to Ammonia

Barboun

Otor

et al. 2022

ACS Sustainable Chem. Eng.

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Nonthermal plasma activation of N2 can facilitate nitrogen adsorption on metal catalysts at low bulk temperatures and atmospheric pressure. We apply a plasma-assisted temperature-programmed reaction (plasma-TPRxn) for ammonia (NH3) synthesis using sequential exposure of a silica-supported metal catalyst to N2 plasma followed by thermal hydrogen treatment while ramping the temperature to decouple the plasma activation of N2 from surface catalyzed hydrogenation steps. This approach eliminates the effects from bulk plasma phase reactions, thereby allowing for direct interrogation of plasma activated nitrogen on the active metal surfaces. We confirm previously reported spectroscopic observations that show plasma-generated surface nitrogen can be converted to NH3 through surface catalyzed pathways. Further, we demonstrate that the ammonia desorption peak temperature is sensitive to metal, with Pt desorbing NH3 at the lowest temperature. Unsteady state microkinetic models of desorption kinetics as a function of initial N coverage and metal recover observed trends in NH3 desorption temperatures and confirm that observed results reflect hydrogenation of plasma-induced N accommodation at each surface. In total, we show that the hydrogenation ability of the catalyst after plasma activation of N2 is responsible for the reactivity trends observed in plasma-assisted NH3 synthesis.

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Section: Experimental Sectionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Plasma-Catalyst Reactivity Control of Surface Nitrogen Species through Plasma-Temperature-Programmed Hydrogenation to Ammonia

Barboun

Otor

et al. 2022

ACS Sustainable Chem. Eng.

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“…The enhancement of NTP-based reactor performance is the main motivation of the “in-plasma catalysis” (IPC) application to C,H,N-based chemistries, ,− where surface reactions have been promoted through direct catalyst exposure to plasma (Figure d). The most typical setup of IPC involves a DBD reactor where a catalytic material (e.g., Al 2 O 3 -supported catalytic beads) is inserted between the two electrodes.…”

Section: Non-thermal Plasma Technology and Its Catalytic Integrationmentioning

confidence: 99%

“…The generation of vibrationally excited species with a lowered surface interaction/adsorption barrier is postulated to be responsible for IPC's effectiveness. 16,24 The types of discharges adopted in DBD IPC configurations operate in a wide range of pulse frequencies, from RF to nanopulsated ones. 8 When liquid materials' exposition to plasma is considered, the technologies adopted include DBD as well as gliding arc (GDA) reactors, in which a periodically extending arc is ignited by a rotating electrode.…”

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confidence: 99%

Integrating Materials in Non-Thermal Plasma Reactors: Challenges and Opportunities

Rosa,

Cameli,

Stefanidis

et al. 2024

Acc. Mater. Res.

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Metrics & MoreArticle Recommendations CONSPECTUS: Electricity-driven chemical processes play a crucial role in mitigating the CO 2 footprint of the process industry. Non-thermal plasmas (NTP) hold significant potential for electrifying the chemical industry by activating molecules through electron-based mechanisms in the absence of thermal equilibrium. However, the broad application of NTPs is hampered by their general inability to direct energy toward a specific chemical pathway, limiting their effectiveness as a selective and scalable technology. Therefore, the integration of NTPs with catalytic materials in a single reactor assembly is being considered more and more to overcome this limitation.Recently, two multifunctional plasma concepts have emerged, demonstrated at small scales. The first concept is in-plasma catalysis (IPC), where a solid catalyst is directly exposed to the plasma discharge. The second concept is post-plasma catalysis (PPC), involving a conventional heterogeneous catalytic step following the plasma activation.Another option explores the combination of non-catalytic materials with plasma, leveraging their distinct physiochemical affinities with molecules for improved selectivity (e.g., membranes and adsorbents), through either in-plasma or post-plasma adoption. Despite these possibilities, the limited understanding of interactions between plasma and surface-adsorbed/permeated species, coupled with discharge-related catalysts and material deactivation, often restricts the design choice to post-plasma catalysis. To harness synergies, energy-efficient NTP technologies are essential. In this context, nanosecond-pulsed discharges (NPDs, also known as nanosecond repetitively pulsed, NRP) emerge as potentially disruptive solutions due to their activation of both electronic and thermal channels. This results in high energy efficiency, facilitating applications such as cleavage of C−C, C−O, and N−N bonds and providing sufficiently high temperatures for thermal integration with post-plasma materials. This integration can be tailored to the NPD product distribution, creating a synergy with conventional materials unique to NTPs and enhancing the overall process throughput.While promising, further advancements in materials science are necessary to maximize the interplay between high-energy bond breakage in plasma and the selectivity enhancement of integrated materials. Our research group has dedicated extensive efforts to the development of multifunctional two-step plasma reactors, with a particular focus on NPD. This has led to remarkable energy efficiency in non-oxidative coupling of methane (NOCM) and CO 2 splitting. Key applications involved a 3D-printed triply periodic minimal surface (TPMS) copper support with a Pd/Al 2 O 3 catalytic layer and a looping process with a CeO 2 /Fe 2 O 3 nanostructured scavenger. The potential of such reactors is vast, given the various applications for which conversion and selectivity currently pose limitations. As current designs are mostly heuristic and the literat...

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“…The assumptions on entropies of adsorption/desorption transition states impact the absolute values of adsorption/desorption rates and the predicted overall rates. The relative rates among materials or at different temperatures, however, are not sensitive to these assumptions . The steady-state coverages and rates at constant pressures were solved with a mean-field microkinetic model, as detailed in our previous works. , In brief, the pressures of gas phase species are fixed and the reactions are evaluated without the presence of products.…”

Section: Computational Detailsmentioning

confidence: 99%

Kinetic Origins of High Selectivity of Metal Phosphides for Ethane Dehydrogenation

Schneider

2022

Ind. Eng. Chem. Res.

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Supercell density functional theory (DFT) calculations are used to create and exercise complete ethane dehydrogenation (EDH) reaction networks over Ni(111) and Ni 2 P(001). EDH intermediates are predicted to be more weakly bound to Ni 2 P than to Ni, with the differences being the greatest for deeply dehydrogenated intermediates. Both C−H and C−C bond cleavage activation energies are generally greater on Ni 2 P than Ni. The implications of these differences are explored through microkinetic models that incorporate a pathway for carbon growth. Ethylene formation rates and selectivities are predicted to be greater over Ni 2 P than Ni across a wide range of temperatures. Ni is predicted to be more susceptible to coke generation. Ethane activation exerts the greatest degree of rate control on both materials; in contrast, the competition between ethylene desorption and dehydrogenation controls selectivity on Ni, while no single step dominates selectivity on Ni 2 P. Results are consistent with previously reported observations, highlight the distinct and active contributions of phosphorus to phosphide surface chemistry, and highlight the role of coking pathways on predicted kinetics.

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Plasma-catalyst modeling for materials selection: challenges and opportunities in nitrogen oxidation

Cited by 8 publications

References 55 publications

Plasma-Catalyst Reactivity Control of Surface Nitrogen Species through Plasma-Temperature-Programmed Hydrogenation to Ammonia

Plasma-Catalyst Reactivity Control of Surface Nitrogen Species through Plasma-Temperature-Programmed Hydrogenation to Ammonia

Integrating Materials in Non-Thermal Plasma Reactors: Challenges and Opportunities

Kinetic Origins of High Selectivity of Metal Phosphides for Ethane Dehydrogenation

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