Hydrogen Peroxide Production

     The most widely used processing method is the AO (Autoxidation) process. The primary use of hydrogen peroxide is the manufacture of "green" bleaching agents such as perborates and percarbonates for the paper and textile industries. Other significant uses include wastewater treatment and hydrometallurgical processes (for example, the extraction of uranium by oxidation). The 1998 U.S. capacity totaled just over 1.1 billion lbs/year, with an anticipated growth of 6-8% per year.

     The reaction mixture fed to the first reactor contains a carrier solvent and anthraquinones (usually 2-ethyl or 2-pentyl-anthraquinone). A stream containing the hydrocarbon-based carrier solvent is usually referred to as the "work solution". This first reactor in the series of two is known as the hydrogenator as hydgrogen is also fed to this reactor and a hydrogenation reaction occurs over a Ni or Pd catalysts.

     The products from the hydrogenator are filtered (to remove catalyst particles) and cooled before being fed to the second reactor which is referred to as the oxidizer. In the second reactor, air or oxygen enriched air is introduced to the work solution to reverse the previous reaction via oxidation.

The contaminated air from the oxidizer is fed to a carbon adsorption unit and then to a vent condenser. The work solution, now containing nearly 40% hydrogen peroxide by weight, is cooled once again before being fed to a liquid-liquid extraction unit. Water is fed to the extractor and acts as the extracting agent. The hydrogen peroxide is miscible in water while the solvents are not. Then the H₂O₂-water layer can be removed and sent to Vacuum Column I and the solvent is sent to be purified before it is recycled.

Feed to Vacuum Column I is preheated with the column condensate (mostly water) which is then either refluxed back to the column or sent to the extractor. In some cases, there are multiple columns to separate the H₂O₂-water mixture from the extractor depending on the deserved purity of the product). While water is removed as an overhead product, the hydrogen peroxide is further concentrated as the bottom product. Finally, the hydrogen peroxide product is cooled before being treated with an inhibitor (to prevent oxidation) and sent to storage.