BE672170A - - Google Patents

Description

  

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    '"PROCESS FOR PREPARING HIGH MOLYBDENE CHLORIDE
PURITY, PREFERRED FROM MOLYBDENE PENTACHLORIDE "
The invention relates to the preparation of high purity molybdenum chloride - preferably molybdenum pentachloride - which is to be processed for the manufacture of molybdenum metal and / or high purity molybdenum combinations.



   Liquid-liquid extraction processes, sublimation of molybdenum trioxide and crystallization of molybdenum compounds are known for the purification of combinations of molybdenum. These processes for preparing high purity compounds are very expensive, respectively do not allow high purity compounds to be obtained, and the removal of tungsten in particular is difficult.



   There are also known methods of purifying

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 molybdenum compounds by distillation or sublimation. In the distillation or sublimation of molybdenum chlorides, and more particularly of molybdenum pentachloride, the product can only be purified to a small extent for elements such as iron, aluminum, and mainly tungsten, if the process is based on the temperatures of distillation or sublimation of their chlorides.



   The invention has given itself the problem of preparing high purity molybdenum compounds by distillation. or sublimation of molybdenum chloride, and in particular of molybdenum pentachloride, according to a process in which elements such as for example iron, aluminum, titanium, silicon, niobium, tantalum and mainly tungsten , are removed from the treated molybdic compound.



   This problem is solved, according to the invention, in that for the preparation of high purity molybdenum chloride by distillation or by sublimation, one adds to the treated product, before and / or during the distillation or sublimation, oxygen, water, gases containing oxygen or water, oxygenated combinations which react easily with metal chlorides, @ and whose reaction products are volatile or easily separable from the treated mass, or do not constitute other additional impurities for the molybdic compound subjected to purification;

   such are, for example, the oxides of molybdenum, of chlorine, of sulfur, of nitrogen, of carbon dioxide, of phosgene, of the oxides of molybdenum and of sulfur, and of other similar products, or of mixtures of these substances.



   This treatment transforms some metal chlorides into oxides of low volatility, and others into oxychlo-

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   more volatile rides, easy to separate from molybdenum pentachloride.



   As purifying agents, oxygen, air, water, chlorides and oxychlorides of molybdenum in particular, have proved their worth.



   The addition of oxygen must be measured at least in an amount sufficient to be able to convert the impurities to be eliminated quantitatively into oxides or oxychlorides, an excess favoring their elimination from the product to be removed. laugh.



   The gases or oxygenated combinations are added before and / or during the distillation or the sublimation of the molybdenum chloride, or introduced into the evaporator.



  With a molybdenum pentachloride thus treated, the volatile oxy- chlorides, and in particular the tungsten oxychloride, distil or sublime at the top and are precipitated in a cold room, while the slightly volatile oxides remain in the mass. . The removal of tungsten, in particular, is already carried out by heating the molybdenum chloride, preferably under reflux, with or without carrier gas.



   The advantages of this process, over the processes known to date for the preparation of high purity molybdenum pentachloride, are convenient and rapid technology, variable production, and excessive cost of reagents to be implemented. and very low yield losses of molybdenum pentachloride.



   The invention is commented on in more detail in the two exemplary embodiments below:.



  1st example of execution.



   To 500 g of molybdenum pentachloride is added dropwise, before distillation, 1 cm3 of water; the chloride is distilled at 280 ° C. with the extension held at 200 ° C.



    @

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 EMI4.1
 
<tb> Elements <SEP> to <SEP> the <SEP> state of <SEP> traces <SEP> ppm <SEP> before <SEP> ppm <SEP> after
<tb>
<tb> Fe <SEP> 60 <SEP> 6
<tb>
<tb> A1 <SEP> 20 <SEP> <<SEP> 0.3
<tb>
<tb> If <SEP> 50 <SEP> <<SEP> 0.3
<tb>
<tb> W <SEP> 20 <SEP> <
<tb>
 2nd example of execution.



   A moderate stream of air is passed for 5 minutes through 500 g of molybdenum pentachloride molten, and the chloride is distilled off after a more or less prolonged time. Distillation at 300 C; extension held at 250 C.
 EMI4.2
 
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  Elements <SEP> to <SEP> the <SEP> state of <SEP> traces <SEP> ppm <SEP> before <SEP> ppm <SEP> after
<tb>
<tb> Fe <SEP> 20 <SEP> 2
<tb>
<tb> Al <SEP> 13 <SEP> <<SEP> 0.3
<tb>
<tb> If <SEP> 90 <SEP> <<SEP> 0.3
<tb>
<tb> w <SEP> 100 <SEP> <<SEP> 1
<tb>
 
These examples of execution relate to a simple distillation; a distillation column allows the purification to be increased at will.

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Claims (1)

CLAIMS 1. Process for the preparation, by distillation or by sublimation, of molybdenum chloride - in particular molybdenum pentachloride - of high purity, characterized in that, before and / or during the distillation or the sublimation, one adds to the treated product oxygen, water, gases containing oxygen or water, oxygenated combinations which react easily with metal chlorides, and whose reaction products are volatile or easily separable of the treated mass, or do not constitute other additional impurities <Desc / Clms Page number 5> for the molybdic compound subjected to purification; such are, for example, the oxides of molybdenum, of chlorine, of sulfur, of nitrogen, of carbon dioxide, of phosgene, of the oxychlorides of molybdenum and of sulfur, and other similar substances, or of mixtures of these substances. 2. A method according to claim 1, characterized in that the oxygenates are introduced into, passed into and / or over the surface of the molybdenum chloride. 3. Process according to claims 1 and 2, characterized in that, in particular, tungsten can be removed as tungsten oxide chloride from molybdenum chloride by heating, with or without carrier gas.