Chemistry of inorganic compounds – Modifying or removing component of normally gaseous mixture – Molecular oxygen or ozone component
Patent
1983-02-16
1985-09-17
Niebling, John F.
Chemistry of inorganic compounds
Modifying or removing component of normally gaseous mixture
Molecular oxygen or ozone component
423588, C01B 1502
Patent
active
045419973
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process for reducing the oxygen content in gas mixtures that may be utilized as protective or inert gases.
In chemical process industries utilizing inflammable gases and liquids, the requirements for oxygen-poor protective or inert gases are considerable. Such is the case for instance in the preparation of hydrogen peroxide according to the so-called anthraquinone process in which anthraquinone derivatives are hydrogenated by means of hydrogen gas to anthrahydroquinone derivatives. The anthrahydroquinone derivative formed is then oxidized with molecular oxygen back to an anthraquinone derivative which forms hydrogen peroxide. One example of such reaction formulae is as follows ##STR1## R=alkyl, for instance C.sub.2 H.sub.5. An inert gas the hydrogenation step of for this process must contain not more than about 1.5% by volume of oxygen.
The inert gas requirements in the anthraquinone process have hitherto been satisfied by energy-intensive methods, for instance by closed combustion of hydrogen with air to water in a nearly stoichiometric hydrogen-oxygen ratio or by combustion of hydrocarbons with air.
In the above-mentioned anthraquinone process for the preparation of hydrogen peroxide, 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.
Surprisingly, it has been found that the oxidation cannot simply be carried out with an anthrahydroquinone-oxygen ratio to result in less than 1.5% by volume of oxygen in the exhaust gas. When the oxygen pressure is lower than 80-100 millibars, and the hydrogen peroxide content in the solution at the same time is higher than 50-100 millimols per liter, considerable amounts of water are formed, whereby the hydrogen peroxide yield and, thus, the production capacity will be reduced. Under the reaction conditions mentioned above, the reaction rate will be reduced.
On the other hand, if the hydrogen peroxide content of the solution is low, the reaction rate, relatively seen, is rather high, and at oxygen pressures below 80-100 millibars, while at the same time the water formation is also low. A controlled low 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. By thus maintaining the hydrogen peroxide content at a level below about 100 millimols per liter, it is possible to reduce the oxygen content of the exhaust gas to the desired level of not more than 1.5% by volume.
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 to produce 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 at 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 accompanying FIGURE shows a diagram of an oxidation process
REFERENCES:
patent: 4374820 (1983-02-01), Guenter
patent: 4428923 (1984-01-01), Kunkel et al.
Boggs Jr. B. J.
EKA AB
Niebling John F.
LandOfFree
Process of reducing the oxygen content in gas mixtures does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process of reducing the oxygen content in gas mixtures, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process of reducing the oxygen content in gas mixtures will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-369462