Oxidative cracking

In some cases the number of oxide layers can be related directly to the number of breaks in the curve and there is then no doubt that the acceleration derives from repetitive stress-induced oxide cracking. 

Polymers Aging Oxidation Cracking (Dil/Con) (Dil/Con) Hydrocarbons Hydrocarbons... 

The adherence of the oxide to the metal substrate may be related to the epitaxial relationships of the oxide-metal system. Bardolle (53) showed that die adherence of the oxide diminished with the multiplication of the epitaxial possibilities. Thus on iron the oxide was less adherent on the Oil and 113 faces than on the 001 faces. The authors observed that when a copper single crystal sphere was heated in oxygen at a high temperature until a thick oxide scale formed on the high rate faces, the oxide cracked and flaked off easily on these faces but adhered tightly on the low rate faces. In this case the high rate faces show the greatest number of possible orientations, whereas the low rate faces show only one orientation. It should be noted that Bardolle s observations indicated that the faces with multiple orientations on iron were slow rate faces. 

Acetone is obtained by fermentation as a by-product of -butyl alcohol manufacture, or by chemical synthesis from isopropyl alcohol from cumene as a by-product in phenol manufacture or from propane as a by-product of oxidation-cracking. 

Our recent studies of cobalt oxides catalyst deposited on y-alumina indicate unexpected activity of C0-O/AI2O3 in oxidative cracking of n-butane at low temperature. High yield of olefins 30% (mostly ethylene and propylene) was reached at 550°C and WHSV - 4.5h" [8]. Furthermore varying of oxygen concentration affects olefins distribution. Such essential features of cobalt oxide catalyst render it interesting as a base for catalyst development. 

Adsorption of oxygen with generation of active species of catalyst is a key factor in oxidative dehydrogenation and oxidative cracking of paraffins. Characterization of the catalysts supports their difference in performance ... 

Oxidizing cracking of butyl acetate. Cracking takes place in the liquid phase in the... 

The highly aromatic character of certain bituminous coals, with a C/H ratio of about 0.8, may offer an interesting source of benzene-carboxylic adds by oxidative cracking. In the presence of potassium salts, these aromatic adds are largely converted to diucids, essentially in the para position. 

Maximum yield of propylene, which occurs near the higher temperature, according to Calderbank et al (9), is only 8.5 wt %, and this is accompanied by 5 wt % ethylene as a co-product. Above 950°F, oxidative cracking is the main reaction, and while yields of light paraffins and unsaturates result, almost no propylene and large amounts of carbon monoxide become the product distribution. 

Thorium and uranium are used in cotmnercial catalytic systems. Industrially, thorium is used in the catalytic production of hydrocarbons for motor fuel. The direct conversion of synthetic gas to liquid fuel is accomplished by a Ni-Th02/Al203 catalyst that oxidatively cracks hydrocarbons with steam. The primary benefit to the incorporation of thorium is the increased resistance to coke deactivation. Industrially, UsOs also has been shown to be active in the decomposition of organics, including benzene and butanes and as supports for methane steam reforming catalysts. Uranium nitrides have also been used as a catalyst for the cracking of NH3 at 550 °C, which results in high yields of H2. 

Coking of metal-oxide cracking catalysts Power law, time on stream Developed correlation for coke on catalyst versus time of reaction... 

Reactions between two solids are analogous to the oxidation of a metal, because the product of the reaction separates the two reactants. Further reaction is dependent on the transport of material across this barrier. As with oxidation, cracking, porosity and volume mismatch can all help in this. In this section, the case when a coherent layer forms between the two reactants will be considered. The mechanism of the reaction may depend on whether electron transport is possible in the intermediate phase, and the rate of reaction will be controlled by the rate of diffusion of the slowest species. To illustrate the problems encountered a typical solid-state reaction, the formation of oxide spinels, is described. 

Oxide cracking occurs when the oxide is put into tension. This is the situation described for the oxidation of Nb in Chapter 4 which results from the growth mechanism of Nb20s. Oxides forming on the alkali metals also form under tension because the PER is less than unity for these systems (Table 5.1). 

Rabo has shown that ALPO s and SAPO s may be used in many chemical and petrochemical processes. They give unique opportunities to be tailored to specific requirements. On the other hand, they have only mild acidity (which could be an Advantage in some cases), they are difficult to synthetize, and they may be more expensive than present commercial zeolites. Therefore they rely on their superior performance to compete with their aluminosilicate cousins. Applications include the removal of nitrogen oxides, cracking of heavy petroleum fractions, octane increase in hydrocracking, various reactions of olefins and aromatics such as oligomerization and xylene isomerization, syngas conversions, and methane activations. Co- and Co-Si-aluminophosphates have been active for this last reaction. 

Reduction of Iron Oxide Cracking of Hydrocarbons (Plastics)... 

Oxidative dehydrogenation and oxidative cracking of alkanes to alkenes... 

It has already been pointed out that, above approximately 400 C, the oxidation of several alkanes yields olefins and only small quantities of oxygenated organic compounds (10). In connection with the problem of olefin production through oxidative cracking of alkanes, let us note that two patents have been taken out (11). 

Wei, Z., Yang, F., Lin, B., Luo, L., Konson, D. Nikbin, K. 2013. Deterministic and probabilistic creep-fatigue-oxidation crack growth modeling. Probabilistic Engineering Mechanics 33(0) 126-134. 

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