Alkylanthraquinone hydrogenation

Figure 11.6 shows the scheme of alkylanthraquinone hydrogenation using the Degussa process. The reaction is carried out in a loop reactor by varying the diameter of the reactor tubes different reactant flow velocities are achievable. 

Hydrogenated vegetable oil, in cosmetic molded sticks, 7 840t Hydrogenation(s), 13 769 acetylene, 1 180 10 613-614 alkylanthraquinone, 14 47 asymmetric, 5 210—212 butadiene, 4 370 carbon monoxide, 5 3 carbon dioxide, 26 881 catalytic, 10 504 catalytic aerogels for, l 763t chlorocarbons, 6 235 conditions of, 10 810 cyclopentadiene and dicyclopentadiene, 8 224-225... 

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... 

Arco have developed an integrated process for the production of industrially important epoxides via an adapted AO process (Figure 1.13).33 34 A sulfonic acid substituted alkylhydroanthraquinone alkylammonium salt is reacted with molecular oxygen to form the alkylanthraquinone and hydrogen peroxide. The hydrogen peroxide is then reacted with an alkene in the presence of a titanium zeolite catalyst (TS-1 see Chapter 4). The epoxide product is then separated, and the anthraquinone salt recycled to a hydrogenator for reaction with... 

Large-scale production of hydrogen peroxide has been put on stream using monoliths for hydrogenation of alkylanthraquinones [37,38,5]. Irandoust et al. [5] studied the process... 

The monolith reactors have found broad applications in gas-phase processes and are at the development stage for catalytic gas-liquid processes. Currently, there is only one process, hydrogenation of alkylanthraquinones in production of hydrogen peroxide, operating on a commercial scale. 

The first reaction, hydrogenation of the alkylanthraquinone, is catalyzed by Pd. The second, the epoxidation of propene by the HP generated by air oxidation of the RAHQ, is catalyzed by TS-1. This is possible because TS-1 activity is not affected by the polynuclear compounds forming the redox couple, since they do not enter the zeolite cages due to steric hindrance (the average diameter of the channel system of TS-1 and TS-2, with ME I and MEL type structures, respectively, is 0.55 nm the cross... 

As noted previously, even if they did form the Diels-Alder adducts, they would not yield alkylanthraquinones because of the absence of hydrogen atoms at the 1- and/or 4-positions. Figure I.B-1 also summarizes the various anthraquinonecarboxylic acids which could arise from the phytadienes depicted. 

Industrially, hydrogen peroxide is almost universally produced by the alternate hydrogenation and oxidation with air of an alkylanthraquinone [2], Although the process is efficient from a yield standpoint, it is quite complex and is carried out in two separate steps, using a stoichiometric amount of expensive high molecular weight quinones e.g. 2-ethylanthraquinone). 

Hydrogen peroxide is an oxidant used in many markets, including the pulp and paper industry. Almost all of the world capacity is based on alternately hydrogenating and oxidizing an expensive alkylanthraquinone. 

In the anthraquinone process, an alkylanthraquinone is catalytically reduced to the corresponding hydroquinone with hydrogen the hydroquinone reacts with oxygen (air), becoming re-oxidized to the anthraquinone derivative, with the formation of hydrogen peroxide. 

Scheme I shows a simplified block diagram illustrating the four main stq>s of a new route to propylene oxide production. In die first step, an alkylanthrahydroquinone, propylene and air react through a series of reactors producing propylene oxide, a minor amount of solvolysis products and water. Propylene oxide is separated by distillation and recovered. In die next step, methanol, propylene glycol and its methyl ether derivatives are extracted widi water and purified. The remaining organic phase passes to the alkylanthraquinone purification/hydrogenation step and finally is fed widi methanol, back to the epoxidation reactors. The regeneration and purification of the working solution are not shown in Scheme I.

Hydrogenation. Alkylanthraquinones (AQ) are catalytically reduced by hydrogen to the corresponding alkylanthrahydroquinone (AQH). The alkyl group can be ethyl [10], or t-butyl [11], and catalysis include Raney nickel or palladium. The catalyst can be suspended, on a fixed bed, or supported. If the catalyst is suspended or supported, a filtration step is included to retain the catalyst, which is then returned to the hydrogenator. 

At the industrial scale, hydrogen peroxide is produced almost exclusively by the alternate oxidation and reduction of alkylanthraquinone derivatives. This anthraquinone process, or AO (from autoxidation) process, was originally developed... 

Large quantities of hydrogen peroxide are commercially obtained from catalytic hydrogenation of alkylanthraquinone to anthrahydroquinone, which is oxidized to hydrogen peroxide and alkylanthraquinone (again). 

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