Reactive at high temperature

Viable methods of producing the metals from oxide ores have to siumount two problems. In the first place, reduction with carbon is not possible because of the formation of intractable carbides (p. 299), and even reduction with Na, Ca or Mg is unlikely to remove all the oxygen. In addition, the metals are extremely reactive at high temperatures and, unless prepared in the absence of air, will certainly be contaminated with oxygen and nitrogen. 

Oxygen supports combustion. It becomes very reactive at high temperatures. The reaction with hydrogen can be explosive. 

Thermal activation can combine stability at low temperature with high reactivity at high temperature. 

Titanium becomes more reactive at high temperatures. It can acmally catch fire when heated in the presence of oxygen. 

Whilst being reactive at high temperatures, zeolite molecular sieves exhibit a high absorption of phosgene at room temperature, a factor which has been utilized in the... 

Whilst the precursors are required to be reactive at high temperatures, they should be stable enough to be carried into the reactor chamber, and no chemical reactions should take place below the deposition temperature. 

Vapor phase oxidation processes prevail over liquid phase processes, although the latter are sometimes used inlarge-scale chemical production when the products (i) can be easily recovered from the reaction medium, as interephthalic acid production, for example (ii) are thermally unstable (i.e., in the production of hydroperoxides and carboxylic acids, except for P-unsaturated compounds) and (iii) are very reactive at high temperature (i.e., epoxides, aldehydes and ketoses, with the exception of ethene oxide and formaldehyde). Liquid-phase oxidation is also preferred in fine chemicals production, although most processes are still non-catalytic. 

Titanium has an atomic weight of 47.90, it melts at about 1800°C and boils at 3262°C. Titanium filings are quite stable against water, moisture or the various other chemicals that we use. The filings are quite reactive at high temperatures (over a red heated state)and produce pretty yellowish white sparks, when they are mixed with a black powder type composition.The front page photos show the sparks in comparison with others caused by aluminium and magnalium. (The author owes the tests to... 

The papers included in this symposium cover the full gamut of problems that had to be addressed. The physical and chemical stability of the catalysts had to be significantly improved over known catalysts in order to meet the 50,000 mile life requirement prescribed by the regulations. The effects of catalyst poisons such as lead, sulfur, phosphorus, etc. were also critical in relation to the limits of deposition that could be tolerated while maintaining catalyst effectiveness. The nature of the catalyst support or substrate became significant in relation to its interaction with the metallic components of the catalyst—adherence, distribution, and reactivity at high temperature. 

The major limitation of titanium is its chemical reactivity with other materials at elevated temperatures. This property has necessitated the development of nonconven-tional refining, melting, and casting techniques consequently, titanium alloys are quite expensive. In spite of this reactivity at high temperature, the corrosion resistance of titanium alloys at normal temperatures is unusually high they are virtually immune to air, marine, and a variety of industrial environments. Table 11.10 presents several titanium alloys along with their typical properties and applications. They are commonly used in airplane structures, space vehicles, surgical implants, and in the petroleum and chemical industries. 

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