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

Catalysis for the valorization of exhaust carbon: from CO2 to chemicals, materials, and fuels. technological use of CO2.

Advanced oxidation processes (AOPs) constitute a promising technology for the treatment of wastewaters containing non-easily removable organic compounds. Chlorophenols (CPs) are a group of special interest due to their high toxicity and low biodegradability. Data concerning the degradation of CPs by means of AOPs reported during the period 1995–2002 are evaluated in this work. Among the AOPs, the following techniques are studied: processes based on hydrogen peroxide (H2O2+UV, Fenton, photo-Fenton and Fenton-like processes), photolysis, photocatalysis and processes based on ozone (O3, O3+UV and O3+catalyst). Half-life times and kinetic constants for CP degradation are reviewed and the different mechanistic degradation pathways are taken into account.

Degradation of chlorophenols by means of advanced oxidation processes: a general review

Atmospheric-pressure plasmas are used in a variety of materials processes. Traditional sources include transferred arcs, plasma torches, corona discharges, and dielectric barrier discharges. In arcs and torches, the electron and neutral temperatures exceed 3000/spl deg/C and the densities of charge species range from 10/sup 16/-10/sup 19/ cm/sup -3/. Due to the high gas temperature, these plasmas are used primarily in metallurgy. Corona and dielectric barrier discharges produce nonequilibrium plasmas with gas temperatures between 50-400/spl deg/C and densities of charged species typical of weakly ionized gases. However, since these discharges are nonuniform, their use in materials processing is limited. Recently, an atmospheric-pressure plasma jet has been developed, which exhibits many characteristics of a conventional, low-pressure glow discharge. In the jet, the gas temperature ranges from 25-200/spl deg/C, charged-particle densities are 10/sup 11/-10/sup 12/ cm/sup -3/, and reactive species are present in high concentrations, i.e., 10-100 ppm. Since this source may be scaled to treat large areas, it could be used in applications which have been restricted to vacuum. In this paper, the physics and chemistry of the plasma jet and other atmospheric-pressure sources are reviewed.

/pdf/the-atmospheric-pressure-plasma-jet-a-review-and-comparison-4n3xn1jiyb.pdf

The atmospheric-pressure plasma jet: a review and comparison to other plasma sources

The need to reduce the accumulation of CO2 into the atmosphere requires new technologies able to reduce the CO2 emission. The utilization of CO2 as a building block may represent an interesting approach to synthetic methodologies less intensive in carbon and energy. In this paper the general properties of carbon dioxide and its interaction with metal centres is first considered. The potential of carbon dioxide as a raw material in the synthesis of chemicals such as carboxylates, carbonates, carbamates is then discussed. The utilization of CO2 as source of carbon for the synthesis of fuels or other C1 molecules such as formic acid and methanol is also described and the conditions for its implementation are outlined. A comparison of chemical and biotechnological conversion routes of CO2 is made and the barriers to their exploitation are highlighted.

Utilisation of CO2 as a chemical feedstock: opportunities and challenges

A comprehensive model of ozone generation in dielectric barrier discharges is presented. The model combines the physical processes in the micro-discharges with the chemistry of ozone formation. It is based on an extensive reaction scheme including the major electronic and ionic processes. The importance of excited atomic and molecular states is demonstrated. Theoretical limits are given for the ozone production efficiency and the attainable ozone concentration. The most important parameters influencing the performance of ozonisers are identified. All theoretical predictions are compared to measured data.

https://iopscience.iop.org/article/10.1088/0022-3727/20/11/010/pdf

Ozone synthesis from oxygen in dielectric barrier discharges

The nature of the silent discharge (dielectric barrier discharge) is reviewed. Theoretical models for describing its discharge physics and ensuing plasma chemistry are presented. The phenomena leading to gas breakdown in such electrode configurations at about atmospheric pressure are discussed. The current transport takes place within a large numer of short-lived microdischarges, the plasma conditions of which are investigated. The theoretical predictions are compared to measurements. Two entirely different applications of silent discharges are treated: industrial ozone production and the formation of excimers to generate ultraviolet radiation. The special capability of the silent discharge for large-scale industrial processing is demonstrated. >

Modeling and applications of silent discharge plasmas

A review is presented of plasma chemical processes occurring in the volume part of electrical nonequilibrium discharges. The role of energetic electrons as initiators of chemical reactions in a cold background gas is discussed. Different discharge types of (glow, corona, silent, RF, and microwave discharges) are investigated with respect to their suitability for plasma processing. Emphasis is placed on the requirements of initiating and maintaining the discharge and, at the same time, optimizing plasma parameters for the desired chemical process. Using large-scale industrial ozone production as an example, the detailed process of discharge optimization is described. Other applications of volume plasma processing include other plasma chemical syntheses as well as decomposition processes such as flue gas treatment and hazardous waste disposal. The author only deals with plasmas which are not in equilibrium. >

Nonequilibrium volume plasma chemical processing

Dielectric-barrier discharges (silent discharges) are non-equilibrium discharges that can be conveniently operated over a wide temperature and pressure range. At about atmospheric pressure electrical breakdown occurs in many independent thin current filaments. These short-lived microdischarges have properties of transient high pressure glow discharges with electron energies ideally suited for exciting or dissociating background gas atoms and molecules. The traditional application for large-scale ozone generation is discussed together with novel applications in excimer UV lamps, high power CO 2 lasers and plasma display panels. Additional applications for surface treatment and pollution control are rapidly emerging technologies. Recent results on greenhouse gas recycling and utilisation in dielectric-barrier discharges are also discussed.

/pdf/dielectric-barrier-discharges-principle-and-applications-58g99jaira.pdf

Dielectric-Barrier Discharges. Principle and Applications

Dielectric-barrier discharges (silent discharges) combine the ease of atmospheric pressure operation with nonequilibrium plasma conditions suited for many plasma chemical processes. In most gases at this pressure the discharge consists of a large number of randomly distributed short-lived microdischarges. Their properties are discussed in detail. Traditionally mainly used for industrial ozone production, dielectric-barrier discharges have found addi- tional large volume applications in surface treatment, high-power CO2 lasers, excimer ultraviolet lamps, pollution control and, most recently, also in large-area flat plasma display panels. Future applications may include their use in greenhouse gas control technologies. Historical aspects, properties and applications of dielectric-barrier discharges are discussed.

/pdf/from-ozone-generators-to-flat-television-screens-history-and-1vqtnixaa4.pdf

Ulrich Dr Kogelschatz

Papers

Ozone synthesis from oxygen in dielectric barrier discharges

Modeling and applications of silent discharge plasmas

Nonequilibrium volume plasma chemical processing

Dielectric-Barrier Discharges. Principle and Applications

From ozone generators to flat television screens: history and future potential of dielectric-barrier discharges