Non-thermal

Penetrante B M, Bardsley J N and Hsiao M C 1997 Kinetic analysis of non-thermal plasmas used for pollution control Japan. J. Appl. Phys. 36 5007-17... 

We have so far assumed that the atoms deposited from the vapor phase or from dilute solution strike randomly and balHstically on the crystal surface. However, the material to be crystallized would normally be transported through another medium. Even if this is achieved by hydrodynamic convection, it must nevertheless overcome the last displacement for incorporation by a random diffusion process. Therefore, diffusion of material (as well as of heat) is the most important transport mechanism during crystal growth. An exception, to some extent, is molecular beam epitaxy (MBE) (see [3,12-14] and [15-19]) where the atoms may arrive non-thermalized at supersonic speeds on the crystal surface. But again, after their deposition, surface diffusion then comes into play. 

There is sfill some dispufe about how microwave irradiation accelerates reactions. Besides the generally accepted thermal effects, one beheves that there are some specific (but also thermal) microwave effects, such as the formation of hot spots . There is still some controversy about the existence of non-thermal (athermal) microwave effects. At the present time, new techniques such as coohng while heating are being investigated and the problem of upscahng... 

Suggest synthetic methods, for the compounds shown below. At least one of the steps in each method should involve energy input from a non-thermal source. Discuss the benefits of using this non-thermal energy source for the particular reaction. 

Photodynamic therapy uses non-thermal red light to activate verteporfin, which produces reactive oxygen species that locally damage the neovascular endothelium.24 Verteporfin treatment reduces the risk of loss of visual acuity and legal blindness over 1 to 2 years. Long-term results are not yet available. Severe photosensitivity for 3 to 5 days after the procedure is common and some patients experience a severe loss of vision. Eventually, most patients have some visual recovery. This procedure requires multiple treatments over time.22... 

Non-thermal plasmas can be produced in a number of ways, including a variety of electrical corona discharges, radio frequency discharges, microwave discharges and electron beams. The most common NTP technologies for emission reduction in engine exhaust streams are the following. 

Szanyi et al., using again in situ IR-TPD coupled skills, studied the effect of acid sites on the catalytic activities of a series of H+-modified Na-Y zeolites in the non-thermal plasma assisted NO reduction reaction using a simulated diesel engine exhaust gas mixture. The acid sites were formed by NH ion exchange and subsequent heat treatment of a NaY zeolite. The catalytic activities of these H+- modified NaY zeolites... 

Kwak, J.H., Peden, C.H.F. and Szanyi, J. (2006) Non-thermal plasma-assisted NO reduction over Na-Y zeolites The promotional effect of acid sites, Catal. Lett., 109, 1. 

Figure 5.4. Catalytic device for DeNOx reaction coupled with non-thermal plasma.

By coupling a non-thermal plasma reactor to a catalytic reactor containing alumina alone, Baudin [32] have observed the DeNO function of alumina at low temperature,... 

NON-THERMAL PLASMA-ASSISTED CATALYTIC NO REMEDIATION, FOR SUBSTITUTING FUNCTIONS 1 AND 2 OF THE MODEL. ACTIVATION OF THE LOW-TEMPERATURE DeNO -FUNCTION 3 OF ALUMINA [32-38]... 

Effect of a dielectric barrier discharge (DBD) type non-thermal plasma on a synthetic gaseous reaction mixture... 

Figure 5.14. Detection of organic products oxygenates and organic nitrogen-containing compounds at the outlet of non-thermal plasma reactor without catalyst. Feed NO (500 ppm) - C3H6 (2000ppm Cj) - 02 (8 vol.%) - N2 [32],...

Figure 5.15. Non-thermal plasma-assisted DeNO reaction over alumina alone, according to Baudin [32], (a) NO, N02, NO and N20 TPD plots, (b) NO conversion vs. T without plasma.

The preceding results suggest an advantageous plasma-catalyst coupling effect on the NO remediation, in full accordance with the proposed mechanism [38], The C H Oz and RNO compounds, produced by the non-thermal plasma before the catalytic reactor... 

The removal of a wide variety of pollutants by means of non-thermal plasma has been reported aliphatic hydrocarbons [1-3], aromatics [4-7], chlorinated hydrocarbons [4,8-10], as well as inorganic contaminants such as S02, H2S [11,12] and NOx, which will be discussed in detail in this chapter. 

REACTION MECHANISMS RESPONSIBLE FOR NO REMOVAL IN NON-THERMAL PLASMA... 

When hydrocarbons are present in the gas mixture, NO removal by oxidation to NOz occurs at much lower input energy and the reaction paths change significantly as compared to the case without hydrocarbons. Numerous works analyze the reaction mechanism of NO. conversion in non-thermal plasma with addition of hydrocarbons, especially ethylene [33,37,77,79,81-83], propylene [35,76,81,83-87], and propane [76,81,85,87],... 

Typical reaction products of NO removal in non-thermal plasma in the presence of propylene, predicted by the model in Martin et al. and Dorai and Kushner [86,88], include formaldehyde (HCHO), acetaldehyde (CH3CHO) methyl oxirane (C3H60), gly-coxal (CHO-CHO), methyl nitrite (CH3ONO), methyl nitrate (CH30N02), and 2-nitroso ethanal (ONCH2CHO). 

The influence of soot on NO removal in non-thermal plasma has been investigated by Dorai and Kushner and Dorai et al. [88,89] in the presence of propylene and propane. Soot particles were assumed to contain only C and H atoms, and were denoted (C Hy). Soot may undergo oxidation when reacting with O and OH radicals generated in the... 

The oxidation of NO to N02 can be considered an advantage when combining plasma with selective catalytic reduction, as it is well-known that at low temperature the efficiency of NO reduction by SCR strongly depends on the N02 concentration in the gas. An oxidation pre-treatment of the gas by non-thermal plasma, prior to the SCR reactor greatly enhances the performance of SCR at temperatures below 500 K. Therefore, the PE-SCR technique is very promising for efficient NO reduction. 

Holzer, F., Roland, U. and Kopinke, F.-D. (2002) Combination of non-thermal plasma and heterogeneous catalysis for oxidation of volatile organic compounds Part 1. Accessibility of the intra-particle volume, Appl. Cat. B Env. 38, 163-81. 

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