Modeling of Direct Synthesis of Hydrogen Peroxide in a Packed-Bed Reactor

Abstract

Direct synthesis of hydrogen peroxide from oxygen and hydrogen continues to be a research topic of high interest. It would be most desirable if this synthesis could be carried out in a continuous fixed-bed reactor in a safe way, with a catalyst providing both high selectivity and high productivity. This could significantly simplify the hydrogen peroxide production process and reduce both operating and investment costs. In the conventional anthraquinone-based production process, the hydrogenation and oxidation steps are carried out in separate reactors, and extraction is finally used for hydrogen peroxide recovery. Recirculation of large quantities of the multicomponent organic working solution takes place, and expensive filtration of the hydrogenation catalyst from this vast stream is required when a slurry reactor is used. The main benefit of the conventional process is that it is a well-proven and reliably operating technology. The most straightforward approach for the direct synthesis is to carry out the reaction between H 2 and O 2 on a heterogeneous catalyst, preferably Pd or Pd/Au catalyst, in a suitable solvent. Methanol is one of the most popular choices for the solvent because the solubilities of H 2 and O 2 in methanol are much larger than those in water. This article presents a modeling study for the direct synthesis of hydrogen peroxide with methanol as the solvent in a continuous three-phase reactor. The modeling study used data from an experimental study performed with a Pd/CeS catalyst in our laboratory reactor. The aim of the modeling was to provide insight into the physical and chemical phenomena occurring during the process. The reaction system was a challenging one, because both side reaction and decomposition reactions took place simultaneously with the highly desirable synthesis. The model was found to describe the experimental data from the fixed-bed reactor rather well. Particle diffusion was found to be most severe for the synthesis and oxidation reactions.

Another Critical Look at Three-Phase Catalysis

“…Hydrodynamics of trickle bed reactors were studied 15,16 using transport modeling, 17 computational fluid dynamics (CFD) modeling, 18 electrical resistance tomography, 19 as well as by high pressures. 20 Due to the reliability of their operation, trickle bed reactors have won a great use in oil industry, and also found applications in SO 2 oxidation, 21 glucose hydrogenation over ruthenium catalyst, 22 hydro-treating atmospheric residue, 23 hydro-purification, 24 catalytic hydro-treatment of vegetable oils, 25 fuel production via Fischer-Tropsch synthesis, 26 hydrogen production by aqueous-phase reforming of xylitol, 27 hydrogenolysis, 28,29 continuous thermal oxidation of alkenes with nitrous oxide, 30 liquid-phase selective hydrogenation of methylacetylene and propadiene, 31 hydrogen peroxide, 32 as well as continuous operation. 33 There are two possible mechanisms in trickle bed reactors for breaking down bubble sizes and initiating dissolution of gas into liquid: (1) the interactions of liquid and gas flows, (2) through the tortoise routes that are formed by the packed catalysts, the denser the solid particles, the smaller the diameters of bubbles so formed.…”

A mathematical model of a slurry reactor for the direct synthesis of hydrogen peroxide

“…2 Although this conventional process is a well-proven and reliable operating technology and has been the dominant method for H 2 O 2 production since the middle of the twentieth century, it has several important drawbacks. 3 The hydrogen peroxide must be produced in large amounts and at concentrations of about 50 wt% or 70 wt% in order to afford economic feasibility, which requires an energy-intensive separation and concentration of H 2 O 2 . The high concentration is necessary to minimize the liquid volume, thus decreasing the transport expenses.…”

Electrochemical H2O2 Production Modelling for an Electrochemical Bandage

“…To date, studies modelling H 2 O 2 production have primarily focused on enzymatic synthesis from glucose, or direct or electrochemical synthesis of H 2 O 2 in fuel cells specific to the application. [18][19][20][21] None of these models are directly applicable to the described e-bandage.…”

“…[14][15][16][17][18][19] for any respective component. For example, the net rate of HOCl in the counter-electrode domain is R…”