Background and Motivation

Hydrogen peroxide (H2O2) is an environmentally friendly oxidizing agent with promising future potential: It is estimated that the current annual production of three megatons will continue to rise to more than five megatons within the next five years. The standard process for industrial H2O2 production is the anthraquinone process. However, due to the many process steps and the limited reusability of organic anthraquinone, this process does not allow a decentralized H2O2 production.

The direct synthesis of hydrogen peroxide on the other hand is an attractive synthesis route in which both molecular hydrogen and oxygen are contacted with a heterogeneous catalyst in a single reaction step. In recent years, intensive research has been conducted on the understanding of the reaction mechanism as well as on new reactor concepts in order to achieve a knowledge-based increase in intrinsic and reactor selectivity, which currently stands in the way of the industrial implementation of this method. The reason for this is that in addition to hydrogen peroxide, water is produced thermodynamically favoured as a by-product in various subsequent and parallel reactions.

At IMVT a novel membrane microreactor is used to overcome these reaction engineering challenges. A polymer membrane allows a bubble-free dosing of the reactants H2 and O2 into the liquid reaction medium which continuously flows through the reaction channel. Due to the alternating dosage of the reactants, the hydrogen peroxide concentration is not limited by the saturation concentration of the gases, as the consumed substances are always „replenished“. At the same time, specially developed 3D-printed channel inserts, so-called flow guiding elements, enable an intensified contact of the gases with the reaction medium. At the same time, these structures serve as carriers for the required catalyst.

Figure 1: Scheme of a fluid guiding element with catalytically coated surfaces (left) [2], 3D-printed fluid guiding element: SEM image of a coated surface and close-up of an uncoated prototype [1] (right).

Topic and Tasks

In previous work and international collaborations, catalytic coatings were successfully applied to the structures using various processes. In order to be able to assess the suitability of these coatings in terms of activity and adhesion to the direct synthesis process, tests are being carried out in an existing reactor setup. The product obtained is to be characterised with regard to its composition by means of UV-vis spectroscopy.

The position is aimed at students from the faculties of chemistry or chemical engineering.

Tasks

• Production of coatings
• Characterization of the coatings
• Conducting tests with the existing plant
• Determination of the achieved concentrations of hydrogen peroxide

Conditions

• Students of chemical engineering / process engineering / chemistry
• Language: English or German

Start: by arrangement

Supervisor: Laura Trinkies (laura.trinkies∂kit.edu)