Induction period powder

Chain-breaking antioxidant DLTP Carbon black Copper powder Induction period at 140°C (h)... 

In several instances an induction period has been observed but this has been shortened by elimination of dissolved oxygen . Deposition of cuprous oxide (Fehling s test) does not appear to influence the zero-order disappearance of Cu(II), but the induction period can be eliminated by adding copper powder (but not Cu20) ° . 

After reduction and surface characterization, the iron sample was moved to the reactor and brought to the reaction conditions (7 atm, 3 1 H2 C0, 540 K). Once the reactor temperature, gas flow and pressure were stabilized ( 10 min.) the catalytic activity and selectivity were monitored by on-line gas chromatography. As previously reported, the iron powder exhibited an induction period in which the catalytic activity increased with time. The catalyst reached steady state activity after approximately 4 hours on line. This induction period is believed to be the result of a competition for surface carbon between bulk carbide formation and hydrocarbon synthesis.(6,9) Steady state synthesis is reached only after the surface region of the catalyst is fully carbided. 

The rapid autocatalytic dissolution of aluminium, magnesium or zinc in 9 1 methanol-carbon tetrachloride mixtures is sufficiently vigorous to be rated as potentially hazardous. Dissolution of zinc powder is subject to an induction period of 2 h, which is eliminated by traces of copper(II) chloride, mercury(II) chloride or chromium(III) bromide. 

It may ignite in moist air [1], The dry powder is very dusty, and suspensions in dry air have a low minimum ignition energy, 17.1 mJ. After an induction period depending on the temperature and humidity of the atmosphere, a sample confined in a Dewar flask decomposed rapidly, with an exotherm of 200°C. Heats of solution in ethanol and in water are 0.63 and 0.65 kJ/g, respectively. [2],... 

The reaction of magnesium and methanol to form magnesium methoxide and used to prepare dry methanol [1] is very vigorous, but often subject to a lengthy induction period. Sufficient methanol must be present to absorb the violent exotherm which sometimes occurs [2], Mixtures of powdered magnesium (or aluminium) and methanol are capable of detonation and are more powerful than military explosives [3],... 

Rate Constants kd and Induction Periods t of Hydroperoxide Decomposition Catalyzed by Mo and MoS2 Powder in Hydrocarbon Mixture (Fuel T-6) [10]... 

We observed a more complicated behavior in the study of retarding action of amines (IV-benzyl-IV -phenyl-l,4-benzenediamine and 4-hydroxyphenyl-2-naphtalenamine) on fuel T-6 oxidation catalyzed by the copper powder [13]. Both antioxidants appeared to retard the autoxidation of T-6 very effectively. They stop chain oxidation during the induction period in concentrations equal to 5 x 10 5mol L 1 and higher. The induction period was found to be the longer, the higher the concentration of the antioxidant and lower the amount of the copper powder introduced in T-6. 

More rudimentary tests to identify the stability of powders are the so-called "hot plate" tests. Here, the substance is placed in a well-defined manner (circular, specified thickness of the layer, and so forth) on a hot plate with a controlled temperature. The temperature in the center of the layer is recorded continuously, and the progress of the self-heating is followed. Observations are made if self-heating of the substance occurs, the induction period of such self-heating, and the extent of the effect such as smoldering or spontaneous ignition. 

A Hydrox mixture can be initiated either by heating it at one point by a heat-producing fuse, by an electrically-heated wire or a blackpowder igniter. A few drops of acid produce a self-sustained reaction, after an induction period. The induction period depends on the nature of the acid solution, its concentration and on the amount of alkaline stabilizer in the Hydrox powder. 

Ti02-A, specific surface area is 1.9 m2/g, further details of properties are listed in fable 12.2), by contrast, the product ratio was a suitable value even at the beginning of the reaction as shown in Fig. 12.2. In general, the finer powder has the higher catalytic activity because of large surface area. For the same reason, on the other hand, higher amounts of intermediates such as H202 are adsorbed on the photocatalyst surface, and this adsorption may cause the induction period. 

Metals. Reaction with Mg is vigorous and often subject to a lengthy induction period. Mixtures with powdered Mg or A1 are capable of powerful detonation.7 Reaction with K may lead to an explosion. Methanol should not be substituted for fert-butanol in the disposal of waste K.8... 

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