Development of electromagnetic wave absorbing catalysts

School of Engineering, University of Warwick

The project:

The laboratory for Energy Intensified Reactor Engineering, together with several academic and industrial partners, performs an ongoing research on application of magnetic catalysts in flow reactors. Our new project aims at the exploration of ferromagnetism assisted plasma catalysis for (i) nitrogen fixation into NH3 or NOx and (ii) CO2 reduction into solar fuels and chemicals under non-thermal plasma conditions. Non-thermal plasma (NTP) is an ionized gas, created in mild conditions by applying electric energy to a gas (for example a potential difference between two electrodes).

The use of magnetic field is known to induce a local temperature hot spot and this was already implemented in cancer therapy. The concept has been recently extended to heterogeneous catalysis where the temperature modulation leads to much higher reaction rates and improved selectivity patterns. However the huge potential of this process in terms of energy efficiency is limited by the need for the development of specific catalysts with high heating efficiency and excellent catalytic activity.

Our assumption is that ferromagnetic domains introduced in catalyst supports would overcome the current limitations of thermal plasma catalysts. Magnetic nanoparticles with a size above the critical size have several magnetic domains that can rotate following the direction of magnetization. The particle size and shape have a large influence on the specific heating power of the catalyst and on the frequency dependence of the catalysts. Nickel ferrite nanoparticles will be obtained with different size and shape by changing the synthesis protocol. The study will be on how to improve further the absorbing properties by making (i) specific shapes (nanoneedles, nanowires), (ii) preferred orientation regarding the magnetic field vector in secondary structures (e.g microtubes composed in individual nanoparticles), and by use of (iii) specific additives to dope the basis material.

The magnetization direction can be switched by external magnetic field running electrical current in an induction coil. The extent to which the catalytic activity can be enhanced by the induction heating will be investigated.