Optimisation of the direct synthesis of H2O2 in water

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Hydrogen peroxide (H2O2) is a green chemical compound widely used because of its strong oxidant properties (Green Chemistry). Some of the hydrogen peroxide applications are related with bleaching process in paper and textile industries, chemical synthesis and waste water treatment. High Pressure Process Group in collaboration with Åbo Akademi from Turku (Finland) have deeply studied the influence of the main reactor parameters and reactor configuration in order to determinate which parameters are the key ones for H2O2 direct synthesis and reactor development.

 Irene Huerta Illera

Irene_Huerta_01  Figure 1. Experimental set-up for H2O2 direct synthesis in a stirred tank reactor

Direct synthesis (DS) is known since the beginning of the 20th century and it is the most promising alternative to produce H2O2. It is an apparently simple reaction based on the contact between hydrogen and oxygen in presence of an active metal that acts as catalyst to produce hydrogen peroxide. However reaction system has some limitations that limit process conditions and reduce the effectiveness, are secondary reactions (water formation, H2O2 decomposition and H2O2 hydrogenation) that can be controlled by the addition of promotes, mass transfer limitations between the catalyst (solid), the reactives (gases) and the reaction medium (liquid), and inflammability of O2 – H2 mixtures that force to operate with H2 concentration lower than 4%.

Irene_Huerta_05Different projects have been developed by this group in order to study the influence of all reaction parameters and to overcome or reduce some of the drawbacks that impede the industrial implantation of the direct synthesis process for H2O2 production.

– Study of the influence of the main reaction parameters in a perfect mixer stirred tank using supercritical CO2 and N2 as reaction inert.

 – Determination of the optimum amount of catalyst (Pd0 over active carbon) and the optimum ratio promoter (Br and H3PO4) – active metal in order to reduce secondary reactions.

 – Design and optimization of an experimental semicontinous reactor to H2O2 production by direct synthesis using supercritical CO2 and N2 as inert.

 – Study of decomposition and hydrogenation reaction, kinetic study and modeling

– Production of H2O2 by DS and reaction conditions optimization in a tricked bed reactor. Proyect realize in Industrial Chemistry and Reaction Engineering Group of the Department of Chemical Engineering at Åbo Akademi University (Finland)

 – Preliminary studies and designs for H2O2 production in a slurry bubble column at high pressure using CO2 or N2 as inert.

Irene_Huerta_02 Figure 2. Low pressure bubble column for mass transfer and hold up determination

 – Development a quantitative continuous Raman method to measure of H2O2 concentration.

Irene_Huerta_04Figure 3. Traditional determination of H2O2 via iodometric titration

 Further information about all the investigations about H2O2 direct synthesis carried out by the High Pressure Process Group can be obtained by contacting with blog authors or consulting bibliography references listed below.

– Moreno, T., J. García-Serna, and M.J. Cocero, Direct synthesis of hydrogen peroxide in methanol and water using scCO2 and N2 as diluents. Green Chemistry, 2010. 12: p. 282-289.

– Moreno, T., et al., Direct synthesis of H2O2 in methanol at low pressures over Pd/C catalyst: Semi-continuous process. Applied Catalysis A: General, 2010. 386(1-2): p. 28-33.

– Moreno, T., et al., Quantitative Raman determination of hydrogen peroxide using the solvent as internal standard: Online application in the direct synthesis of hydrogen peroxide. Chemical Engineering Journal, 2011. 166(3): p. 1061-1065.

– Moreno, T., J. García-Serna, and M.J. Cocero, Decomposition reaction of H2O2 over Pd/C catalyst in an aqueous medium at high pressure: Detailed kinetic study and modelling. The Journal of Supercritical Fluids, 2011. 57(3): p. 227-235.

– Moreno Rueda, T., J. García Serna, and M.J. Cocero Alonso, Direct production of H2O2 from H2 and O2 in a biphasic H2O/scCO2 system over a Pd/C catalyst: Optimization of reaction conditions. The Journal of Supercritical Fluids, 2012. 61(0): p. 119-125.

– Huerta, I., J. García-Serna, and M.J. Cocero, Hydrogenation and decomposition kinetic study of H2O2 over Pd/C catalyst in an aqueous medium at high CO2 pressure. The Journal of Supercritical Fluids, 2013. 74(0): p. 80-88.

– Huerta, I., et al., Effect of the low hydrogen to palladium ratio in the direct synthesis of H2O2 in water in a trickle bed reactor. Catalysis Today 2014. Submmited.

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