Anthraquinone auto oxidation process

In the chemical industry, more than a megaton of hydrogen peroxide is produced yearly in a biphasic reaction scheme known as the anthraquinone auto-oxidation process, where reduced anthraquinone is used to reduce oxygen to H2O2 and where the anthraquinone is reduced again by hydrogen on a palladium catalyst. 

The alkylated anthraquinone process accounts for over 95% of the world production of H202, mainly because the it operates under mild conditions and direct contact of 02 and H2 is avoided. In this process, 2-alkylanthraquinone (the alkyl group is typically an ethyl, terf-butyl or amyl group) is dissolved in a mixture of a non-polar solvent (C9-Cn alkylbenzene) and a polar solvent [Trioctyl phosphate (TOP), or tetrabutyl urea (TBU) or diisobutyl carbinol (DIBC)] and then hydrogenated over a precious metal (Pd or Ni) catalyst in a three-phase reactor (trickle bed or slurry bubble column) under mild reaction conditions (<5bar, <80 °C) to generate 2-alkylanthrahydroquinone [1-3, 5], The latter is then auto-oxidized with air in a... 

On an industrial scale, the predominant manufacturing process for hydrogen peroxide is by the auto-oxidation of anthraquinone. The North American hydrogen peroxide production was estimated to be 445-520 million lbs in 1989 [20]. Electrochemical processes can compete with this process for small scale operations. At hydrogen peroxide production rates below 3-4 tons/day, electrochemical processes have a cost advantage [23]. 

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