Plasma-catalysis processing

Different aspects of total oxidation processes are reviewed in the first part of the book hydrocarbon oxidation (Chapter 1) and soot oxidation (Chapter 2) for mobile appficafions while oxidation of volatile organic compounds (VOC) is treated in the next five chapters. Chapter 3 provides a general overview of VOC oxidation while chlorinated VOCs are specifically discussed in Chapter 4 and persistent VOC in Chapter 5. Plasma catalysis processes for VOC abatement are reviewed in Chapter 6. Finally, Chapter 7 gives the point of view of industry for the development and applications of catalysis for air depollution technologies. Total oxidation is also used for energy production by combustion processes exemplified in Chapter 8. The last two chapters are devoted to oxidation processes in liquid media by electrochemical techniques (Chapter 9) or more generally as "advanced oxidation processes" for water depollution (Chapter 10). 

Positive ions are obvionsly major players in plasma-chemical processes. Their exothermic reactions with neutrals usually have no activation energy, which makes their contribution significant in many specific plasma-chemical processes, particularly in plasma catalysis. In addition to high chemical activity, the ions can have significant kinetic eneigy, which determines their contribntion, for example, in reactive ion etching. 

Other Processes of Decomposition, Elimination, and Isomerization of Hydrocarbons in Non-Equilibrium Plasma Plasma Catalysis... 

Plasma Catalysis in the Process of Hydrogen Production by Direct Decomposition (Pyrolysis) of Methane... 

The 0/C ratio in the process is 1.23, which is close to the ideal partial oxidation reaction. The process produces nitrogen-diluted syngas containing up to 45% of H2 + CO. The output syngas flow rate is 2.7 standard m /h, which is equivalent to 8.6 kW of output power. In terms of plasma catalysis, discharge power in this case (0.1 kW) is only 1.2% of the total power of the produced syngas. Reaction (10-12) proceeds with the total absence of soot. 

Combined Plasma-Catalytic Approach Versus Plasma Catalysis in Processes of Hydrogen Production by Partial Oxidation of Hydrocarbons... 

Mutaf-Yardimci, O. (2001), Plasma-Catalysis in Hydrocarbon Processing by Using Non-Equilibrium Plasma Discharges, Ph.D. Dissertation, University of Illinois at Chicago, Chicago, IL. 

Krawczyk, K., Motek, M. (2001). Combined plasma-catalytic processing of nitrous oxide. Applied Catalysis B Environmental, 30, 233-245. 

Further insight into the mechanism of plasma-assisted catalysis can be gained by studying the temperature dependence of the oxidation process and comparing the decomposition of the DCM as a frmction of temperature for both plasma catalysis and thermal catalysis The catalyst is incorporated into the barium titanate packed-bed plasma reactor in a one-stage configrrration. The reactor can be heated to 400°C with an electric heater. Figure 6.6 shows the temperature variation for the decomposition of DCM with a catalyst. 

The use of plasma catalysis can increase the energy efficiency of the abatement process for both propane and propene, but the effect of the addition of a catalyst is modest in the case of propane processing but quite dramatic for propene, as shown in Fig. 6.8, where 100% destruction can be achieved at a plasma energy density of 20 J litre The equivalent destruction for propene in the absence of a catalyst at this energy would be only 50%. In both cases, the most effective material was found to be y-alumina which may result from reactions involving surface OH species as was seen for DCM and also the effectiveness of y-alumina as an absorbent which will increase the processing time within the plasma. 

Many of the plasma catalysis schemes described in this chapter are not optimised in a way that is suitable for processing large volumes of waste gas in an efficient manner on a larger scale. Plasma reactors are generally limited to rather low gas flows compared to normal waste gas emissions and are presently best suited to niche applications of small flows with low concentrations of pollutants. A more energy-efficient configuration can be constructed where the pollutant is initially adsorbed... 

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