Dielectric-barrier discharges (silent discharges) are used on a large industrial scale. They combine the advantages of non-equilibrium plasma properties with the ease of atmospheric-pressure operation. A prominent feature is the simple scalability from small laboratory reactors to large industrial installations with megawatt input powers. Efficient and cost-effective all-solid-state power supplies are available. The preferred frequency range lies between 1 kHz and 10 MHz, the preferred pressure range between 10 kPa and 500 kPa. Industrial applications include ozone generation, pollution control, surface treatment, high power CO2 lasers, ultraviolet excimer lamps, excimer based mercury-free fluorescent lamps, and flat large-area plasma displays. Depending on the application and the operating conditions the discharge can have pronounced filamentary structure or fairly diffuse appearance. History, discharge physics, and plasma chemistry of dielectric-barrier discharges and their applications are discussed in detail.

https://www3.nd.edu/~sst/teaching/AME60637/reading/2003_PCPP_Kogelschatz_dbd_review.pdf

Dielectric-barrier Discharges: Their History, Discharge Physics, and Industrial Applications

Catalytic removal of NO

Plasma–liquid interactions represent a growing interdisciplinary area of research involving plasma science, fluid dynamics, heat and mass transfer, photolysis, multiphase chemistry and aerosol science. This review provides an assessment of the state-of-the-art of this multidisciplinary area and identifies the key research challenges. The developments in diagnostics, modeling and further extensions of cross section and reaction rate databases that are necessary to address these challenges are discussed. The review focusses on non-equilibrium plasmas.

/pdf/plasma-liquid-interactions-a-review-and-roadmap-4kfoerpjnh.pdf

Plasma-liquid interactions: A review and roadmap

It is well known that urbanization and industrialization have resulted in the rapidly increasing emissions of volatile organic compounds (VOCs), which are a major contributor to the formation of secondary pollutants (e.g., tropospheric ozone, PAN (peroxyacetyl nitrate), and secondary organic aerosols) and photochemical smog. The emission of these pollutants has led to a large decline in air quality in numerous regions around the world, which has ultimately led to concerns regarding their impact on human health and general well-being. Catalytic oxidation is regarded as one of the most promising strategies for VOC removal from industrial waste streams. This Review systematically documents the progresses and developments made in the understanding and design of heterogeneous catalysts for VOC oxidation over the past two decades. It addresses in detail how catalytic performance is often drastically affected by the pollutant sources and reaction conditions. It also highlights the primary routes for catalyst deactivation and discusses protocols for their subsequent reactivation. Kinetic models and proposed oxidation mechanisms for representative VOCs are also provided. Typical catalytic reactors and oxidizers for industrial VOC destruction are further discussed. We believe that this Review will provide a great foundation and reference point for future design and development in this field.

/pdf/recent-advances-in-the-catalytic-oxidation-of-volatile-zw2c35dbg7.pdf

Recent Advances in the Catalytic Oxidation of Volatile Organic Compounds: A Review Based on Pollutant Sorts and Sources.

Catalytic oxidation of volatile organic compounds (VOCs) – A review

In this work, comprehensive investigation was done on the oxygen partial pressure-dependent behavior of the various catalysts using a flow-type plasma-driven catalyst (PDC) reactor. These data provide a useful guideline for the optimization of the cycled system using adsorption and the O 2 plasma-driven catalysis of adsorbed volatile organic compounds (VOCs). The potentials of the tested catalysts for the cycled system were evaluated based on the enhancement factor and the adsorption capability. All the tested materials (TiO 2 , γ-Al 2 O 3 , zeolites) exhibited positive enhancement factor, while negative values with the dielectric-barrier discharge (DBD) plasma alone. TiO 2 catalysts showed the highest enhancement factor of about 100 regardless of the type of metal catalysts and their supporting amount. Based on the experimental findings in this study and the literature information, a plausible mechanism of plasma-driven catalysis of VOCs was suggested.

Oxygen partial pressure-dependent behavior of various catalysts for the total oxidation of VOCs using cycled system of adsorption and oxygen plasma

The current status of plasma-catalysis research and the associated possible applications are outlined. A basic explanation of plasma chemistry is given, which is then used as a foundation to indicate the research vector for the ongoing development of various applications. As an example of an environmental application, volatile organic compound decomposition using plasma-catalysis is discussed in depth, from the fundamental concept to the current industrial application status. As a potential application of plasma-catalysis towards the realization of a future “hydrogen society”, ammonia synthesis is discussed in terms of current social attitudes and regulations, along with historical developments. Additionally, up-to-date information on the fundamentals of the nonthermal plasma interaction with a catalyst is provided.

/pdf/plasma-catalysis-for-environmental-treatment-and-energy-45rwb0g6ju.pdf

Plasma Catalysis for Environmental Treatment and Energy Applications

Benzene oxidation with ozone over supported manganese oxide catalysts: effect of catalyst support and reaction conditions.

This paper describes the decomposition of gas-phase benzene using a plasma-driven catalyst (PDC) reactor packed with 1.0 wt.% Ag/TiO2 catalysts. The decomposition of benzene preferentially produced CO2 and CO, and formic acid as minor one. Carbon balance based on these products was satisfactory at around 100%. For the concentration lower than 110 ppm, the PDC reactor successfully decomposed benzene with specific input energy of around 130 J/l, where the formation of nitrogen oxides was small. The plasma-induced catalytic activity appeared only during plasma application and disappeared as the plasma was turned off. Thermal catalysis showed that temperature was not an important parameter in the decomposition of benzene using the PDC reactor. Comparison of the effects of dilution gases (Ar, N2) on the benzene decomposition revealed that the contribution of UV light from the plasma to the activation of Ag/TiO2 catalyst was negligible. The contribution of catalytic reaction became dominant as increasing specific input energy. The removed amount of benzene showed zero-order to the initial concentration of benzene and determined mostly by specific input energy to the PDC reactor.

Decomposition of gas-phase benzene using plasma-driven catalyst (PDC) reactor packed with Ag/TiO2 catalyst

This paper presents the effect of different catalysts on the decomposition of benzene and toluene using flow-type plasma-driven catalyst (PDC) system. Three representative materials of titanium dioxide, two types of gamma-alumina and two zeolites were tested. Several types of metal catalysts (Ag, Ni, Pt, Pd) and their loading amount were also investigated for the optimization of the PDC system. Three key factors of energy consumption, carbon balance and safety of products were emphasized in evaluating the performance of different catalysts. The type of catalysts greatly influenced on the carbon balance, CO2 selectivity, ozone formation, while no much difference was observed in the degree of enhancement in energy efficiency. Pt/gamma-Al2O3 catalyst was found to be effective in enhancing the CO2 selectivity. The CO2 selectivity increased as Ag-loading amount on TiO2 catalyst increased. The 4.0 wt% Ag/TiO2 catalyst was effective in suppressing the formation of NO2 and N2 O. Zeolites showed comparable decomposition efficiency and good carbon balance, while the CO2 selectivity was poor compared to the other catalysts. Mechanical mixing of 2.0 wt% Ag/H-Y zeolite with Pt/gamma-Al2O3 was effective in enhancing the CO 2 selectivity without changing other performance

Atsushi Ogata

Papers

Oxygen partial pressure-dependent behavior of various catalysts for the total oxidation of VOCs using cycled system of adsorption and oxygen plasma

Plasma Catalysis for Environmental Treatment and Energy Applications

Benzene oxidation with ozone over supported manganese oxide catalysts: effect of catalyst support and reaction conditions.

Decomposition of gas-phase benzene using plasma-driven catalyst (PDC) reactor packed with Ag/TiO2 catalyst

Effect of different catalysts on the decomposition of VOCs using flow-type plasma-driven catalysis