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
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B15/00—Peroxides; Peroxyhydrates; Peroxyacids or salts thereof; Superoxides; Ozonides
  • C01B15/01—Hydrogen peroxide
  • C01B15/022—Preparation from organic compounds
  • C01B15/023—Preparation from organic compounds by the alkyl-anthraquinone process

Definitions

• the present invention relates to a process for reducing the oxygen content in gas mixtures that may be utilized as protective or inert gases.
• R alkyl, for instance C 2 H 5
• An inert gas for this process must contain not more than about 1.5% by volume of oxygen.
• inert gas requirements in the anthraquinone process have hitherto been satisfied by energy-intensive methods, for instance by closed combustion of hydrogen wirh air to water in a nearly stoichiometric hydrogen-oxygen ratio or by combustion of hydrocarbons with air.
• the oxidation of the anthrahydroquinone derivative is carried out such that the hydrogen peroxide yield, based upon the anthrahydroquinone content in the starting solution, will be as high as possible when the oxygen source is air.
• the oxidation therefore is carried out with excess air such that the exhaust gas will have an oxygen content of 4-10% by volume.
• the pressure in the oxidation reactor is usually maintained at 3-6 bars.
• the exhaust gas from this oxidation process could be used as a protective gas for the hydrogenation reaction if its oxygen content could be reduced to not more than 1.0-1.5% by volume.
• the reaction rate, relatively seen, is rather high, also at oxy-gen pressures below 80-100 millibars while at the same time the water formation is low.
• a decreasing content of hydrogen peroxide in the solution will enhance the possibility of performing the oxidation at a low oxygen pressure, while maintaining a high hydrogen peroxide yield.
• the present invention thus concerns a process of reducing the oxygen content in gas mixtures to 0.0 - 1.5% by volume, in which process the gas is contacted with a solution containing anthrahydroquinone derivatives capable of being oxidized with molecular oxygen under formation of hydrogen peroxide, and which process is characterized in that the supply of oxygen is so adjusted that the amount of oxygen supplied, upon quantitative formation of hydrogen peroxide, stoichiometrically corresponds to not more than 90% of the supplied amount of anthrahydroquinone derivative, and in that the hydrogen peroxide content of the solution a the contact surfaces between the solution and the gas is not more than 100 millimols per liter at a simultaneous oxygen pressure of not more than 100 millibars.
• the oxygen preferably is supplied in an amount which stoichiometrically corresponds to not more than 50% of the. supplied amount of anthrahydroquinone derivative.
• the process according to the invention may preferably be carried out continuously in any type of oxidation reactor, for instance a tubular reactor or in one or more columns. If a column is used, the solution and the gas may be conducted in a co-current flow from the top to the base of the column, or vice versa. Also a counter-current flow may be employed, i.e. the gas is introduced at the base of the column and the solution at the top. In order to obtain a large contact surface between the gas and the liquid, the columns prefer ably are provided with built-in nettings or perforated bottoms, or filled with packings.
• the oxidation temperature may amount to 20-100oC, preferably 40-70°C.
• the pressure within the oxidation reactor may be 0.8-10 bars, but preferably is limited to 1-6 bars.
• the solvents utilized for the anthrahydroquinone solution may be selected optionally among such solvents as are suitable for the anthraquinone process.
• the process according to the invention implies a partial oxidation of the anthrahydroquinone content in the solution.
• this solution contains further unoxidized anthrahydro quinone derivative which may be finally oxidized in known manner, whereupon the hydrogen peroxide can be recovered for instance by extraction with water.
• the process according to the invention may be utilized to reduce the oxygen content in all types of gas mixtures, provided that they do not contain any gas capable of reacting with the solvents or the remaining constituents of the solution in an undesired manner.
• the exhaust gas which is obtained from the oxidation system usually employed in the preparation of hydrogen peroxide by the anthraquinone process may, like , be used for generating oxygen-poor gas mixtures according to the invention.
• the product gas can be purified from solvent vapours in known manner, for instance by freezing and/or adsorption on active carbon. If a very low content of oxygen in the product gas is absolutely essential, any residual content after the process according to the invention has been carried out can be removed, for instance by catalytic combustion.
• Oxygen-poor exhaust gas mixtures from the process according to the invention may thus be utilized as protective gas in, inter alia, the hydrogenation. step of the anthraquinone process. After suitable purification, they may be used as protective and inert gases also within other fields of application and may constitute the starting material for the preparation of, for instance, liquid nitrogen, noble gases and ammonia.
• the solution initially contained 15 millimols of THEAHK and 111 millimols of hydrogen peroxide per liter.
• the oxygen content of the air was reduced during 200 minutes to 5.3% by volume. After a further 40 minutes, the oxygen content in the gas was still 5.3% by volume.
• the solution then contained 3 millimols of THEAHK and 117 millimols of hydrogen peroxide.
• THEAHK per liter were introduced continuously.
• air was introduced at the column base at a constant flow, such that the oxygen supply amounted to 102 millimols per liter of supplied THEAHK solution.
• Both the exhaust gas and the partially oxidized THEAHK solution left the column at the top thereof.
• the pressure at the column base was 3.28 bars, and 2.45 bars at the top.
• the oxygen content of the exhaust gas was 0.6% by volume.
• the oxygen process is shown in the Figur . EXAMPLE 4
• the solution leaving the column contained 138 millimols of THEAHK and 105 millimols of hydrogen peroxide per liter.

Landscapes

• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Analytical Chemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Gas Separation By Absorption (AREA)
• Oxygen, Ozone, And Oxides In General (AREA)

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• 1981
  • 1981-07-08 SE SE8104242A patent/SE426808B/sv not_active IP Right Cessation
• 1982
  • 1982-06-28 WO PCT/SE1982/000228 patent/WO1983000139A1/en not_active Ceased
  • 1982-06-28 EP EP82902097A patent/EP0082864B1/en not_active Expired
  • 1982-06-28 DE DE8282902097T patent/DE3262974D1/de not_active Expired
  • 1982-06-28 US US06/467,478 patent/US4541997A/en not_active Expired - Fee Related
  • 1982-06-28 JP JP57502107A patent/JPS58501072A/ja active Granted
  • 1982-07-05 CA CA000406637A patent/CA1186869A/en not_active Expired
• 1983
  • 1983-03-01 FI FI830677A patent/FI68603C/fi not_active IP Right Cessation

Patent Citations (1)

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