Pyrophoric iron

In the 1950 s, crude oils were either corrosive (sour), or non-corrosive (sweet). Crudes containing more than 6 ppm of dissolved H2S were classed as sour because, beyond this limit, corrosion was observed on the walls of storage tanks by formation of scales of pyrophoric iron sulfides. 

At the beginning of the twentieth century, the incandescent mantle, utilising the candoluminescence of a mixture of thorium (95% weight) and cerium oxides was developed. The pyrophoricity of rare-earth metals led to the invention of the lighter flint made through the alloying of iron and mischmetal. Since that time, numerous other appHcations have developed to coincide with the availabiUty of the rare-earth compounds on an industrial scale and having a controlled purity. 

Reactions of monoethan olamine with mild steel are referenced in the Hterature (23). The complex formed, identified as triseth an o1 amin o—iron, can decompose in air to pyrophoric iron, with the potential to cause a fire, if contacted with combustible materials. 

Lighter Flints and Getters. Traditionally the item most widely associated with cerium has been the pyrophoric iron-mischmetal (- 0%) alloy for lighter flints, in limited use in the 1990s. Similar low vapor pressure reactive alloys based on cerium, such as Th2Al-MM, can also be used as getters for electronic equipment and vacuum tubes (see Electronic materials Vacuumtechnology). 

Care should be exercised in filtering the reaction mixture. The solid collected is largely finely divided iron and is pyrophoric, so it should not be allowed to dry. 

Regeneration with air can be done with continuous or periodic addition of small amounts of air. Both must be done carefully because of exothermic reaction. Regeneration is never complete, so the beds must be eventually changed out. This must be done carefully because of the pyrophoric (spontaneously combustible) nature of the iron sulfide. The entire bed is wetted first. 

Co304 with an excess of n-butyl lithium results in further lithiation of the oxide particles, but with a concomitant extrusion of very finely divided transition metal from the rock salt structure. Highly lithiated iron oxide particles are pyrophoric if exposed to air [100]. 

Inorganic oxides are usually prepd by intimate contact between the element and oxygen or air. The reaction may be rapid and exothermic, as when finely divided pyrophoric materials ignite spontaneously in air or oxygen. Examples of these materials are iron, lead and phosphorus.-Or, the reaction may be slow as when iron oxidizes when exposed to ordinary moist air, or when aluminum oxidizes at the surface upon exposure to air. Much of the time oxidation re-... 

Some materials such as oil-impregnated cotton and iron pyrites are prone to spontaneous combustion, whilst selected materials such as metal alkyls and metals in a finely divided state burn on immediate contact with water or air. These are termed pyrophoric . Examples and precautions for their control are described in Chapter 6. 

There are pyrophoric forms of iron, which combust spontaneously in air if they are heated above 180°C. 

See pyrophoric iron-sulfur compounds See other corrosion incidents... 

Thermally unstable basic iron(III) maleates produced from mixtures of the above may be pyrophoric. 

The solid chelate is pyrophoric in air, binning to iron(III) oxide. 

The oxide (prepared at 300°C) bums in air above 200°C, while the finely divided oxide prepared by reduction may be pyrophoric at ambient temperature [1]. That prepared by thermal decomposition under vacuum of iron(II) oxalate is also pyrophoric [2],... 

See Other METAL SULFIDES, PYROPHORIC IRON-SULFUR COMPOUNDS... 

Reduced iron, potassium and pyrophoric manganese all ignite in the gas at ambient temperature. Magnesium filings bum vigorously when heated in the gas [1]. Slightly warm sodium ignites in contact with the gas, and interaction with calcium is explosive [2],... 

Thermolysis of Fe(C0)5, f°r example, gives pyrophoric, finely divided iron powder ( 19) ultraviolet photolysis (20) yields Fe2(C0)9, via the intermediate Fe(C0)4 multiphoton infrared photolysis in the gas-phase (2M) >(22) yields isolated Fe atoms. Multiple ligand... 

For on-board fuel processing, there are two principal concerns (1) the feasibility of keeping the iron-chrome and copper oxide catalysts in the reduced state, especially during periods of shutdown and (2) the pyrophoric nature of the copper oxide catalyst in the reduced state [29], Because of these concerns, considerable research and development is being conducted to develop new WGS catalysts for on-board fuel processing. 

---