Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/34—Chemical or biological purification of waste gases
  • B01D53/46—Removing components of defined structure
  • B01D53/68—Halogens or halogen compounds
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B7/00—Halogens; Halogen acids
  • C01B7/01—Chlorine; Hydrogen chloride

Definitions

• the present invention concerns a process for removing nitrogen trihalides from mixtures which contain them.
• it concerns a process for the destruction of nitrogen trichloride contained in gas or liquid mixtures, for. example in mixtures containing liquid or gaseous chlorine and nitrogen trichloride.
• the nitrogen triha-lides are very unstable compounds whose decomposition can often be accompanied by violent defiagration.
• the nitrogen trihalides are found in a large number of mixtures which contain halogens, it is necessary to remove them because of their instability.
• thermal or photochemical processes have been used to destroy the nitrogen trihalides. These processes have not proved satisfactory because, in addition to the fact that they are expensive and difiicult to carry out, they do not lead to a complete destruction of the nitrogen trihalides, and this means that a mixture which only contains a small amount of these impurities cannot be purified.
• Monel metal is employed to describe alloys containing 60 to 70% Ni, 25 to 35% Cu, 1 to 3% Fe, 0.25 to 2% Mn, 0.02 to 1.5% Si and 0.3 to 0.5% C (Bennett: Concise Chemical and Technical Dictionary, 1962). These alloys may possibly contain small amounts of Co and Al.
• the process which constitutes the object of the invention is carried out in an exceedingly simple manner: In the case of gaseous mixtures, it is suflicient to let them pass over a filter consisting of piles of turnings or coarse grains of Monel metal. In the case of a liquid, a certain amount of Monel metal turnings are introduced into the medium and it is allowed to react for a given period.
• the alloy remains active for a long time and can readily be regenerated by treating it with water in order to dissolve off the salts formed on its surface before it is dried by a suitable method (for instance by treating it with acetone and airing in a current of air).
• liquid or gaseous chlorine contains an amount of bromine greater than p.p.m. it is convenient to submit it to a preliminary debromination treatment in order to reduce the bromine content to a value less than 100 p.p.m. in order to derive the full benefit of the process which constitutes the object of the present invention.
• EXAMPLE 1 This example is given by way of comparison; it concerns the treatment of gaseous chlorine containing variable amounts of nitrogen trichloride (expressed in parts per million) by means of copper turnings, nickel turnings and a mixture of copper and nickel turnings, the copper and nickel being in the proportion of 30:70 by weight, i.e. very substantially in the proportion of these metals in Monel metal.
• the filter employed has a height of mm. and a diameter of 45 mm.
• the rate of flow of the chlorine is 20 CIlL/SEC. The operation is carried out at room temperature.
• Example 2 The same conditions as in Example 1 are observed but the filtering element used to fill the filter consists of turnings of Monel metal of the composition Ni 65%, Cu 31%, Fe 1.5%, Si 0.3%, Mn 0.8%, C 0.2% and Co 0.4%.
• a filter of diameter 150 mm. and height 500 mm. has been fitted on the collector of concentrated chlorine from an electrolytic cell with a mercury cathode.
• the nitrogen trichloride content of the concentrated chlorine had varied between 3 and 6 p.p.m.
• EXAMPLE 3 This example deals with the destruction of nitrogen trichloride in liquid chlorine. For this purpose, Monel metal turnings are introduced into liquid chlorine and the reaction is allowed to continue until the instant when the destruction of the nitrogen trichlorideis complete.
• Process for the decomposition of nitrogen trichloride in a mixture containing it as an impurity comprising contacting said mixture with a natural alloy known as Monel metal, said alloy being in the form of particles and containing 60 to Ni, 25 to 35% Cu, 1 to 3% Fe, 0.25 to 2% Mn, 0.02 to 1.5% Si and 0.2 to 0.5% C, whereby nitrogen trichloride is decomposed and removed from said mixture and recovering the thus-purified mixture.
• a natural alloy known as Monel metal said alloy being in the form of particles and containing 60 to Ni, 25 to 35% Cu, 1 to 3% Fe, 0.25 to 2% Mn, 0.02 to 1.5% Si and 0.2 to 0.5% C
• Process according to claim 10 in which the period of contact is about 0.6 second provided that the content of nitrogen trichloride in the chlorine is not greater than 12.
• Process according to claim 9 in which said mixture is further comprised of bromine and said mixture is subjected to a preliminary debromination treatment in order to reduce its bromine content to a value less than 100 ppm.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Organic Chemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Biomedical Technology (AREA)
• Environmental & Geological Engineering (AREA)
• Analytical Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Treatment Of Water By Oxidation Or Reduction (AREA)
• Conductive Materials (AREA)
• Manufacture And Refinement Of Metals (AREA)
• Heat Treatment Of Articles (AREA)
• Solid-Sorbent Or Filter-Aiding Compositions (AREA)

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Publications (1)

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Citations (3)

• 1964
  • 1964-10-29 DE DES93962A patent/DE1232933B/de active Pending
  • 1964-11-28 ES ES0306515A patent/ES306515A1/es not_active Expired
• 1965
  • 1965-01-07 CH CH21365A patent/CH455721A/fr unknown
  • 1965-01-11 US US424851A patent/US3361536A/en not_active Expired - Lifetime
  • 1965-01-20 FI FI0126/65A patent/FI43425B/fi active
  • 1965-01-28 NL NL6501096A patent/NL6501096A/xx unknown
  • 1965-02-05 FR FR4567A patent/FR1424111A/fr not_active Expired
  • 1965-02-16 GB GB6653/65A patent/GB1069062A/en not_active Expired

Patent Citations (3)

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