Oxidations in gas phase

VYa Shtern. Mechanism of Hydrocarbons Oxidation in Gas Phase. Moscow Izdatelstvo AN SSSR, 1960 [in Russian]. 

Statement (c) is partially correct—while ozone is considered a pollutant, it is very unlikely that the ozone pollution is caused by the diffusion of this gas from the stratosphere. Rather, this ozone is formed from other atmospheric pollutants (such as nitrogen oxides) in gas-phase atmospheric reactions. 

WUhams, T.B. The determination of nitric oxide in gas phase cigarette smoke by non-dispersive infrared analysis Beifr. Tabakforsch. Int. 10 (1980) 91-99. 

Fig. 3 Extrapolation of the maximum absorption transition energy, Fmax of the mesityl oxide in gas phase, = —0.111, as 43,630 cm (229.2 nm) using a linear regression in the plot of the experimental Emax [16] versus the normahzed Reichardt solvent polarity scale, Ej [2]. The solvents and experimental values (E x nd Ej) are (1) iso-octane (43,365 cm = 230.6 nm and 0.012), (2) chloroform (42,088 cm =...

Raillard C, Hequet V, Le Cloirec P, Legrand J (2004) Kinetic study of ketones photocatalytic oxidation in gas phase using Ti02-containing paper effect of water vapor. J Photochem Photobiol A 163 425 31... 

The definition above is a particularly restrictive description of a nanocrystal, and necessarily limits die focus of diis brief review to studies of nanocrystals which are of relevance to chemical physics. Many nanoparticles, particularly oxides, prepared dirough die sol-gel niediod are not included in diis discussion as dieir internal stmcture is amorjihous and hydrated. Neverdieless, diey are important nanoniaterials several textbooks deal widi dieir syndiesis and properties [4, 5]. The material science community has also contributed to die general area of nanocrystals however, for most of dieir applications it is not necessary to prepare fully isolated nanocrystals widi well defined surface chemistry. A good discussion of die goals and progress can be found in references [6, 7, 8 and 9]. Finally, diere is a rich history in gas-phase chemical physics of die study of clusters and size-dependent evaluations of dieir behaviour. This topic is not addressed here, but covered instead in chapter C1.1, Clusters and nanoscale stmctures, in diis same volume. 

Wall Loss of Oxidation Products. It is known that some classes of hydrocarbons (the higher terpenes, for instance) are prolific aerosol formers when subjected to atmospheric oxidation. Other classes, aromatic hydrocarbons for instance, although they do not form large amounts of suspended aerosol, have been shown to lose (at least under some conditions) large amounts of oxidation products to the reaction vessel walls. The fate of these oxidation products in the open atmosphere remains open to question, as does the extent to which they continue to participate in gas-phase chemistry (187). 

The purpose of this work was to increase the A3 selectivity at low conversion through a catalyst modification. Previous studies of phenol alkylation with methanol (the analogue reaction) over oxides and zeolites showed that the reaction is sensitive to acidic and basic properties of the catalysts [3-5]. It is the aim of this study to understand the dependence of catalyst structure and acidity on activity and selectivity in gas phase methylation of catechol. Different cations such as Li, K, Mg, Ca, B, incorporated into y-Al203 can markedly modify the polarisation of the lattice and consequently influence the acidic and basic properties of the surface [5-8] which control the mechanism of this reaction. 

The first one is the direct synthesis of metallic nanoclusters, not via formation of (hydro)oxides and their reduction in gas-phase, because the successive reduction for formed (hydro)oxides sometimes results in the size growth of metal particles due to the aggregation and/or sintering. The second one is the use of precisely designed metal complexes, which are well adsorbed on the support surfaces, as shown in Figure 1. 

Thus, we considered a number of examples of application of the sensor technique in experiments on heterogeneous recombination of active particles, pyrolysis and photolysis of chemical compounds in gas phase and on the surface of solids, such as oxides of metals and glasses. The above examples prove that, in a number of cases, compact detectors of free atoms and radicals allow one to reveal essential elements of the mechanisms of the processes under consideration. Moreover, this technique provides new experimental data, which cannot be obtained by other methods. Sensors can be used for investigations in both gas phase and adsorbed layers. This technique can also be used for studying several types of active particles. It allows one to determine specific features of distribution of the active particles along the reaction vessel. The above experiments demonstrate inhomogeneity of the reaction mixture for the specified processes and, consequently, inhomogeneity of the... 

Maira, A.f., Yeung, KL, Lee, C.Y., Yue, P.L, and Chan, C.K. (2000) Size effects in gas-phase photo-oxidation of trichloroethylene using nanometer-sized Ti02 catalysts. Journal of Catalysis, 192 (1), 185-196. 

Pillai, U.R. and Sahle-Demessie, E. (2002) Selective oxidation of alcohols in gas phase using light-activated titanium dioxide. Journal of Catalysis, 211 (2), 434—444. 

Different Mechanisms of the Aliphatic Hydrocarbon Oxidation in Gas and Liquid Phases... 

DIFFERENT MECHANISMS OF THE ALIPHATIC HYDROCARBON OXIDATION IN GAS AND LIQUID PHASES... 

FIGURE 2.2 Topology of different mechanisms of hydrocarbon oxidation in gas and liquid phases in coordinates hydrocarbon oxidation (log[RH]) versus temperature (1 IT) [290],... 

Just as in gas phase kinetics, reactive molecular beam-surface scattering is providing important molecular level insight into reaction dynamics. There is no surface reaction for which such studies have proven more illuminating than the carbon monoxide oxidation reaction. For example Len, Wharton and co-workers (23) found that the product CO exits a 700K Pt surface with speeds characteristic of temperatures near 3000K. This indicates that the CO formed by the reactive encounter of adsorbed species is hurled off the surface along a quite repulsive potential. 

Vigorous oxidations are frequently explosive reactions. The reacting oxygen may be supplied from the atmosphere (e.g., in gas phase explosions) or from... 

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