Advances in the direct synthesis of hydrogen peroxide from hydrogen and oxygen

The direct synthesis of hydrogen peroxide presents an attractive and atom efficient route to an important commodity chemical. The direct synthesis process has attracted considerable research interest into catalysts which could provide an alternative to the current industrial process. Many catalyst systems have been evaluated, most of which utilise Pd as the active component. The activity of the catalysts can be promoted in a number of ways, either by addition of a second metal, or by adding promoters into the reactant phase such as acid and halides. Acidic supports can increase the activity of catalysts without addition of aqueous acids by minimising the decomposition of hydrogen peroxide, and catalysts can be doped with halide ions to minimise the non-selective hydrogenation reaction. The addition of gold to form bimetallic particles has also been shown to increase hydrogen peroxide yield by increasing hydrogen selectivity without the need to add acid and halides. If the process was to ever be envisaged as a competitor to the anthraquinone process it would need to be operated in a continuous system. Recent research has focused on the use of continuous reactor systems such as membrane, fixed bed and microreactors. Recent literature regarding catalyst design and continuous process development as well as historical perspective of the process is discussed in this review. (C) 2014 Elsevier B.V. All rights reserved.