Catalytic dissociation

The Fischer-Tropsch process has attracted renewed interest as a way to produce high quality, sulfur-free diesel fuel from natural gas and, possibly, an opportunity to utilize natural gas at remote oilfields. The process represents proven technology and is regarded as an alternative for when oil may no longer be widely available, and one has to resort to natural gas and coal. In a really futuristic scenario one may even contemplate the use of GO and H2 produced by photo-catalytic dissociation of GO2 and water. 

Peer-reviewed journals [72, 73] proceedings [74] sections in reviews [14, 83, 89, 90, 115] additional information [73] general theoretical analysis on optical photo-catalytic dissociation [140],... 

The Fig. 8 f shows a glass cell which is positioned on a four-hole capillary. The diameter of the cells is 20 mm. Cells with an orifice diameter of 0.5—5 mm are needed depending on the vapor pressure of the sample. The position of the thermocouple is so arranged, that the hot junction is in the center of the substance without direct contact. In the same temperature range metal cells (A1 or stainless steel) can also be used when the above mentioned effect of catalytic dissociation does not occur. Alu-... 

As follows from this example, catalytic dissociation of H202 generates OH radicals in the system and under definite conditions induces another reaction. In this regard, with respect to the particular objective of generating free radicals to the system, H202 may possess... 

It is common knowledge that transition metals are effective catalysts for redox processes, including H202 dissociation. Of the greatest interest is catalytic dissociation of H202 in the liquid phase in the presence of small amounts of bi- and trivalent iron salts (the Fenton reagent [4]). The reaction mechanism primarily suggested by Haber and Weiss [5] was then complemented by Bard [6] ... 

In this context, works [20, 21] should be mentioned, in which 0 2 ion-radicals were ESR detected in all samples of solution quickly frozen after initiation of H202 catalytic dissociation on metals and oxides (applied on A1203). The ion-radicals mentioned occur on the surface and desorb to the liquid phase, where, with high probability, they induce free radical processes. These results conform to the Weiss mechanism (6.3) of H202 dissociation on heterogeneous catalysts. 

This system contains two chemically conjugated reactions H202 catalytic dissociation in the presence of HW04 and olefin epoxidation. For these reactions, peroxy tungstic acid or, most likely, peroxy tungstate ions form the general intermediate substance. 

Nitrous oxide control options at various stages of development included thermal catalytic reduction of N2O in the presence of methane, conversion of N2O to recoverable NO and use of this to prepare nitric acid, and catalytic dissociation of N2O to nitrogen and oxygen (Eq. 19.69-19.73) [33, 34]. 

Different options are available for the abatement of nitrous oxide (i) N2O decomposition in boilers (thermal destruction, efficiency higher than 98%), (ii) conversion of N2O into recoverable NO and (iii) catalytic dissociation of N2O to N2 and O2 (efficiency higher than 90-95%) [9]. 

One mechanism for the synthesis of ammonia proposes that N2 and H2 molecules catalytically dissociate into atoms ... 

Interdiflusion between the components of catalyst coatings and substrates can also lead to catalyst deactivation. If Nb, Ta, Ti, V or Zr diffuses through palladium or other noble metal protective layers and reacts on the outer surface to form stable oxides, carbides or nitrides, the catalytic dissociation of molecular hydrogen can be poisoned. Interdiffusion, linked to loss of hydrogen flux, has been reported by Edlund and McCarthy [47] and Pagheri et al. [56]. Membrane surfaces can also become depleted of palladium if palladium diffuses into the substrates. Apparent complete loss of palladium has been observed by Rothenberger et al. for 40 nm thick Pd films on Ta foils after 48 h use at 1173 K (900 °C) [41]. 

Litovchenko V.G., Efremov A.A. (1999), The enhanced catalytic dissociation of adsorbed hydrogen containing molecules , Cond. Matter Phys., 3(19), 561. 

The palladium-gate devices have been shown to respond to hydrogen sulphide (28). The devices were shown to follow a half-power law similar to the response to hydrogen. The response was considered to be due to the formation of atomic hydrogen from the catalytic dissociation of the hydrogen sulphide (again similar to the response of hydrogen). 

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