Oxidation testing

The most common technique for estimating thermal stability is called the Jet Fuel Thermal Oxidation Test (JFTOT). It shows the tendency of the fuel to form deposits on a metallic surface brought to high temperature. The sample passes under a pressure of 34.5 bar through a heated aluminum tube (260°C for Jet Al). After two and one-half hours, the pressure drop across a 17-micron filter placed at the outlet of the heater is measured (ASTM D 3241). 

There are available standard accelerated oxidation tests that consist of passing air or oxygen through an oil at elevated temperature. The test is conducted with or without the presence of catalysts or water. 

A sequence of tests has been devised to evaluate antioxidants for use in automotive crankcase lubricants. The Indiana Stirring Oxidation Test (ISOT) JISK2514 is an example of a laboratory screening test. The oil is stirred at 165.5°C in the presence of air. Copper and iron strips are used as metal catalysts. The development of sludge, viscosity, and acidity are deterrnined periodically. Failure time is determined when the development of acidity requires... 

The properties of 1,1-dichloroethane are Hsted ia Table 1. 1,1-Dichloroethane decomposes at 356—453°C by a homogeneous first-order dehydrochlofination, giving vinyl chloride and hydrogen chloride (1,2). Dehydrochlofination can also occur on activated alumina (3,4), magnesium sulfate, or potassium carbonate (5). Dehydrochlofination ia the presence of anhydrous aluminum chloride (6) proceeds readily. The 48-h accelerated oxidation test with 1,1-dichloroethane at reflux temperatures gives a 0.025% yield of hydrogen chloride as compared to 0.4% HCl for trichloroethylene and 0.6% HCl for tetrachloroethylene. Reaction with an amine gives low yields of chloride ion and the dimer 2,3-dichlorobutane, CH CHCICHCICH. 2-Methyl-l,3-dioxaindan [14046-39-0] can be prepared by a reaction of catechol [120-80-9] with 1,1-dichloroethane (7). 

Oxidation. Atmospheric oxidation of 1,2-dichloroethane at room or reflux temperatures generates some hydrogen chloride and results in solvent discoloration. A 48-h accelerated oxidation test at reflux temperatures gives only 0.006% hydrogen chloride (22). Addition of 0.1—0.2 wt. % of an amine, eg, diisopropylamine, protects the 1,2-dichloroethane against oxidative breakdown. Photooxidation in the presence of chlorine produces monochloroacetic acid and 1,1,2-trichloroethane (23). 

Oxidation. 1,1,1-Trichloroethane is stable to oxidation when compared to olefinic chlorinated solvents like trichloroethylene and tetrachloroethylene. Use of a 48-h accelerated oxidation test gave no hydrogen chloride, whereas trichloroethylene gave 0.4 wt % HCl and tetrachloroethylene gave 0.6 wt % HCl (22). 

Finally, oxidation rates obviously increase with increasing partial pressure of oxygen, although rarely in a simple way. The partial pressure of oxygen in a gas turbine atmosphere, for example, may well be very different from that in air, and it is important to conduct oxidation tests on high-temperature components under the right conditions. 

Obtain all available information about the material. If it is a surplus or off-specification product, obtain an analysis or a Material Safety Data Sheet. If it is a waste, check for previous analyses, and if none exists, obtain one. (Even if a previous analysis exists, consider running a few screening-type field analyses for confirmation of important properties such as pH, redox potential, or other oxidizer test such as cyanide, sulfide, and flashpoint.)... 

Ammonia oxidation Test drawn during manufacturing process to evaluate the ammonia oxidation rate for the nitrifiers. 

The principal use of this oxidative test for hydration is to locate quickly the probable site of hydration, which can then be confirmed by inserting a methyl group as described in Section II, C. 

The stringent requirements covering oxidation stability are defined by the test method DIN 51352, Part 2, known as the Pneurop Oxidation Test (POT). This test simulates the oxidizing effects of high temperature, intimate exposure to air, and the presence of iron oxide, which acts as catalyst - all factors highly conducive to the chemical breakdown of oil, and the consequent formation of deposits that can lead to fire and explosion. 

Rotary-screw compressor mineral oils oxidation resistance is assessed in a modified Pneurop oxidation test using iron naphthenate catalyst at 120°C (250°F)... 

Table 7.17 Results of oxidation tests on nickel-chromium alloys ...

Oxidation tests on Nimonic 90A, in which sodium chloride was introduced into the atmosphere, showed that this constituent produces a significant deterioration in the protective nature of the normally adherent film. Although under certain service conditions the presence of sodium chloride is likely, this is not always so, and thus the general applicability of the results of laboratory tests in sodium sulphate and mixtures involving sodium chloride may be questioned. Test procedures for hot-salt corrosion have been reviewed by Saunders and Nicholls who concluded that burner rig testing is the most appropriate procedure provided contaminant flux rates similar to those found in an operating turbine are used in the rig. 

Photocatalytic oxidation tests were performed in a photoreactor [2]. The flat, rectangular stainless steel reactor has dimensions of 578 mm x 113 mm and inlet/outlet ports at the two ends. The aerogel catalyst placed in a recess located at the center of the reactor was uniformly irradiated by... 

Fig. 3. Photocatalytic oxidation test of titania-silica aerogels, (a) TCE (air 400 seem, TCE 113 ppm), (b) isopropanol (air 200 seem, isopropanol 268 ppm).

CO oxidation tests on Au supported on various metal oxides were undertaken at low CO concentrations, where the adiabatic temperature rise in the bed is negligible. Since CO oxidation is highly exothermic, when high CO concentrations are present in the feed 1%), and at high conversions, the adiabatic temperature rise in the catalyst bed due to the heat of reaction may be as high as 100 C. Therefore, it is important to monitor the catalyst bed temperature when high CO concentrations are present in the feed. 

Au/metal oxides are active for low temperature CO oxidation. The activity of the catalysts is very sensitive to catalyst preparation. All the Au/metal oxides tested for room temperature CO oxidation deactivated substantially with time. The deactivation... 

Results of the cyclohexane oxidation tests are shown in Table 41.4. Mono-oxygenated products are cyclohexanone, cyclohexanol and cyclohexyl hydroperoxide. Cu and Cr were very active, but subsequent tests showed considerable leaching for both metals, whereas Co-Si-TUD-1 did not show ai r leaching. Tests with different Co loadings indicate that the lowest Co concentration has the best conversion and ketone selectivity. Isolated cobalt species are most efficient for the conversion of cyclohexane, as agglomeration of Co reduces... 

The low allylic alcohols (< 6%) yield suggests that the alcohol is reoxidized to the corresponding ketone, probably by Fe =0 species (M = O) (29). Alcohol oxidation tests (Figure 49.2) confirm that the formation of alcohol is an intermediate step in the synthesis of the corresponding ketone, equations 9-11. 

Various pyridazine-A-oxides (including cinnoline A-oxides) have been prepared as potential antitumour agents in Japan [276-278]. Among several 4-nitro-pyridazine 1-oxides tested for activity against rat ascites hepatoma AH-13, 3,6-dimethoxy-4-nitropyridazine 1-oxide (74) has been found to be the most potent compound a minimal effective dose of 5 mg/kg has been estimated [276], Also pyridazine A-oxides of type (75) bearing a bis(2-chloroethyl)ami-nomethyl side-chain at C-6 have been reported to be effective (0.5-5 mg/kg, i.p.) against AH-13 in rats [278]. Both types of compound (74), (75, R = H, Br), however, have been shown to be inactive against mouse lymphoid leukaemia L-1210. 

Argon and oxygen for 02/Ar oxidizer tests were supplied from high-pressure gas bottles. Steam for H2O oxidizer tests was supplied by a 150 psig electric steam boiler and was superheated to 600 °F using electric heaters. To start a H2O oxidizer test run, the steam flow was first set to the required rate for the test condition. An amount of oxygen sufficient to complete combustion of the aluminum was then mixed with the steam, and a flow of propane into the combustor was initiated. 

Figure 8.2 Typical measured hemispherical emissive power distribution for the 02/Ar oxidizer test. 1 — Port 7 Data, 2 — Fit T = 2887 K, EM = 0.46...

Figure 8.4 Measured temperature and radiation intensity distributions for the 02/Ar oxidizer test in 24-inch long combustor. 1 — temperature, 2 — power, 425-800 nm... 

Figure 8.6 Particle size distribution for combustion products collected during H2O oxidizer test... 

Figure 8.7 Combustion products particle size distributions for O2 oxidizer tests 1 — 02/Ar, 2 — H2O...

Figure 8.8 Particle size distribution of fuel and unburned fraction in products from H2O oxidizer test 1 — fuel, 2 — products...

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