Radiofrequency heating for process intensification in metal catalysed hydrogenation over composite magnetic microparticles.

Duration: 05.01.2011 – 04.01.2014
Sponsor: DEL
Ph.D student: Thomas Houlding

Recently, much research in process intensification has been focussed on the development multi-functional reactors, improving processes by system integration. The use of NiZn ferrite nanoparticles embedded in a mesoporous microparticle for radiofrequency (RF) heating, and magnetic separation provides a novel process intensified platform for system integration. The objective of this study was to explore novel metal supported catalysts for selective and economically viable fine chemical synthesis.
The methodology of characterising RF heating of magnetic nanoparticles (MNPs) depends whether those are powders or in solution. Powders give the highest heating rate as the largest density of active material is present but parameters such as packing density, ambient humidity and thermal contact with the probe need to be considered as even small changes in either of these parameters result in different heating responses. Thus it is difficult to obtain reproducible results. Suspending the material in a solvent improves heat transfer between MNPs and the probe but decreases the heating response.
Induction coils with either 4, 5 or 6 turns were used as applicators to generate RF fields with different frequencies. The heating rates are studied as a function of ferrite composition (Ni and Zn content), the total loading of ferrite onto titinia microparticles as well as of the field strength and frequency.
The catalytic activity of composite catalysts in hydrogenation reactions is determined in a reactor made of PEEK. Reference experiments are carried out using conventional heating with a thermostat. During transient experiments under RF-field, the liquid temperature remains considerably below the catalyst temperature which opens up new selective pathways for chemical synthesis.