Intrinsically Safe Operations and Microreactors

This approach offers several advantages over a conventional suspended catalyst It guarantees safe operation of the process due to the separated supply of both gaseous 

272 8 Direct Synthesis of Hydrogen Peroxide Recent Advances 

Various studies and some patents have been published on the use of membrane catalysts for the direct synthesis of H202 [73-81]. The redox treatment of the membrane influences the properties both in the synthesis and decomposition of H202. Formation of a hydrophobic layer improves the selectivity, because it limits the consecutive decomposition of hydrogen peroxide, limiting the chemisorption of H2 and re-adsorption of H202 [73]. Either polymeric or ceramic-type membranes could be used, but the latter are preferable to allow more robust operations. The mono- or bi-metallic Pd-based active component could be deposited either in the form of dispersed particles (e.g., by precipitation-deposition) or of a thin film (e.g., by 

Reproducibly of results, however, was questioned, because the total oxidation reaction was underestimated [84]. Possibly, these discrepancies derive from the observation of structural changes of the Pd-based membrane during direct hydroxylation of benzene to phenol [85]. The surface state of Pd during the reaction could be divided into two major regions the oxidized region near the gas 

A few fundamental studies have also been reported on the topic of hydrogen peroxide synthesis by direct combination of H2 and 02 in a microreactor. A recent contribution ofVoloshin et al. [86] from the Stevens Institute ofTechnology shows the first results on the role of reaction conditions. A maximum concentration of 1.3 wt% H202 was achieved. Further studies are necessary, but this interesting direction warrants further investigation. 

H2O2 was achieved. Further studies are necessary, but this interesting direction warrants further investigation. 

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