Oxidation high pressure

CI2 into alkaline solutions of Br ). lodates can be prepared either by direct high-pressure oxidation of alkali metal iodides with oxygen at 600° or by oxidation of I2 with chlorates ... 

HP-OIT High-pressure oxidative induction emission spectrometry... 

Shannon, R. D., Chenavas, J., and Joubert, J. C. (1975). Bond strength considerations applied to cation coordination in normal and high pressure oxides. J. Solid State Chem. 12, 16-30. 

In the Nippon Mining Company process,163 the aqueous feed consists of a solution of cobalt, nickel and other metal sulfates obtained by the high-pressure oxidative leaching of a mixed metal sulfide ore. Following the removal of iron and copper by chemical precipitation methods, and the successive extraction of zinc and cobalt by organophosphorus acid reagents (Section 63.3.2.2) under weakly acidic conditions, the pH value of the solution is adjusted to between 9 and 9.5 with ammonia, and nickel is extracted into a 25% solution of LIX 64N in an alkane solvent. 

Catalyst life depends on several variables. High-pressure oxidation operations (which also operate at higher temperatures, per Table 22.16) require more frequent catalyst regeneration. The presence of trace amounts of iron, calcium, MoS2 (lubricants), and phosphorus in the ammonia feed has been shown to shorten catalyst life. Deposits of iron oxides tend to catalyze the conversion of ammonia and oxygen to nitrogen and water, rather than to nitric oxide. These effects, as well as poor ammonia-air mixing and poor gas distribution across the catalyst, may reduce the yield by up to 10 percent 91,97... 

W.J. Pitz and C.K. Westbrook, Chemical Kinetics of the High Pressure Oxidation of -Butane and its Relation to Engine Knock, Comb, and Flame 63 (1986) 113. 

To shorten the time for the oxidation test method, a test for sludge formation in transformer oil by high-pressure oxidation bomb has been devel-... 

In the discussion of the oxidation at atmospheric pressure it was pointed out that in general surfaces and catalysts had been found to be detrimental to the production of methanol and formaldehyde. The results of high pressure oxidation, however, lead to an entirely different conclusion namely, that good yields, based on the hydrocarbon reacted, of methanol and formaldehyde may be obtained in the presence of metallic and inert surfaces and that the governing factor is not the kind of surface present but the velocity of the reacting gases over the surface (time of contact). Rates of flow of gas over the catalytic surface in excess of 0.20 liters per hour per square centimeter of superficial catalyst surface must... 

Because of manufacturing demands for lower process temperatures, interest in two alternative oxidation techniques has been rekindled. One technique is high pressure oxidation. From the L-P model we can see that an increased oxidant pressure will accelerate transport across the growing film and thereby increase the rate. This technique was identified in the 1960 s (27) but was ahead of... 

Y. M. Ercil, "A Study of Passivation of Germanium by High Pressure Oxidation, Ph.D. Thesis, Brown University, Providence, RI, (1981). 

The oxide isolation has one additional key limitation. The overall thickness of the oxide is practically limited to about 1.0 pm. Greater thicknesses would require an inordinate amount of process time (somewhat offset with the use of high pressure oxidation methods). Furthermore, further thicknesses would also require additional lateral areas consumed during the oxidation process. Thus, in the final analysis, this process technology does not completely have the desireable features for the full extendibility required for VLSI applications. 

This could be encountered in high-pressure oxidation reactions, for example. From typical profiles shown in Fig. 6.3.f-l, it follows that when there are B and R profiles the R selectivity in the film is lower than that in the bulk. In such a case, higher selectivity can be expected when the amount reacting in the bulk is large as compared to that reaaing in the film. 

The crystal structure of a solid can influence the properties of a material, for example, the structure must be noncentric for a material to demonstrate antiferromagnetic, ferromagnetic, ferroelectric, or piezoelectric behavior. Rapid cooling of a sample from high temperature and/or high pressure can quench in a structure that is not stable at room temperature or atmospheric pressure. High-pressure oxide polymorphs, which are more dense, have been studied to model the earth s interior. Furthermore, unique crystal structure characteristics of a material can allow stmcture-property variation, for example, insertion compound formation in layered materials. 

A series of high pressure oxidative induction time measurements (HPOIT) were conducted on a PE geomembrane sheet in order to investigate the interaction of the pressure and temperature variables on the induction time. The experiments consisted of determining the EffOIT at constant cell volume employing a wide operational range of pressure and temperature values. The HPOIT test results were found to be inversely related to both variables, with temperature being the predominant factor (Tikuisis et al. 1985). 

T. Tikuisis, P. Lam, M. Cossar, High Pressure Oxidative Induction Time Analysis By Differential Scanning Calorimetry (TA Instruments Inc., TA085, 1985)... 

High-pressure oxidation in CO2 has hardly been studied so far [6]. Moreover, the few reports which have been published are on catalyzed oxidation [7,8,9]. Our investigations on oxidation in carbon dioxide, in which methanol, ethanol, and toluene were used as model substances, were conducted not only to test the feasibility of such an integrated process, but also to learn more about the role of water during high pressure oxidation for example in supCTcritical water (SCW) from comparative experiments. 

The model description of the measured differences in high pressure oxidation is not satisfactory concerning the influence of small wato amounts. Eiiher the model is not complete or th e is a specific solvent effect in addition to the pressure effect on the chemical kinetics. Until now the reaction rate of elementary reactions at high pressure has been measured only in helium [e.g. 32] Calculation of the fugacity coefficients of the HO2 free radical in supCTcritical water also shows specific solvent interactions as a consequence of partial charges [33]. It can be assumed that these inta actions are much lower in supCTcritical carbon dioxide which may lead to somewhat different reaction rates of elementary reactions in the reaction network. 

High-pressure oxidation in carbon dioxide shows the same high conversion rates of the model compounds as in oxidation in supercritical v/ater. However small differences are found even if small amounts of water are added to carbon dioxide. The oxidation of methanol at 420°C and 25 MPa leads to a smalls CO content and lower oxygen conversion if small amounts of water are added into the mixture before reaction. 

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