CORDIS - EU research results

RF-enhanced Microprocessing for Fine Chemicals Synthesis using Catalysts Supported on Magnetic Nanoparticles

Final Report Summary - RFMIFICS (RF-enhanced Microprocessing for Fine Chemicals Synthesis using Catalysts Supported on Magnetic Nanoparticles)

This project aimed at application of non traditional energy sources and structured reactors for newly emerging liquid phase catalytic processes for, amongst others, fine chemicals and pharmaceuticals synthesis. It is widely accepted that the activity of a solid catalyst suspended in a liquid phase can benefit greatly from the use of smaller catalyst particles to avoid mass-transfer limitations. However, the difficulties with handling and manipulation and of small particles in the reaction mixture severely circumvent their industrial applications.
In this project, a set of novel core-shell composite magnetic nano- and micro-particles has been developed for induction heating and magnetic actuation. The obtained particles have very high heating rate (up to 50 K/s in a fixed bed reactor) and/or they can be manipulated by an external magnetic field of 0.5 Tesla (in a slurry reactor). The outer surface of these particles was functionalized to use them in important classes of industrial reactions: oxidations with molecular oxygen, selective hydrogenation and direct amide synthesis. In general, the synthesized composite catalysts showed improved catalytic activity towards direct amide formation under RF heating compared to conventional heating. The obtained catalysts demonstrated high selectivity, which was typically by 20-30% better than present industrial catalysts.
A magnetic actuation set-up has been designed and constructed to enhance mass transfer rate in laminar flow using composite magnetic microparticles. Using this device, particle motion in the fluid was investigated in a sinusoidal magnetic field generated by a dual coupled quadrupole arrangement of electromagnets around the reactor. The mass transfer of a reactant to the reacting surface of the particle was investigated under different actuation conditions. An optimum frequency, voltage and phase shift has been found to obtain the maximum mass transfer rate in the reactor. The magnetic actuation allows to increase mass transfer rate by a factor of 2.5 under laminar flow conditions. This, in turn, allows to apply higher reactant concentrations which leads to process intensification. A correlation for Sh number has been developed under magnetic actuation conditions. The true interdisciplinary nature of process intensification is apparent in this line of research, combining aspects of reactor engineering, materials, catalysis and magnetism research.
A near-isothermal micro-trickle bed reactor operated under radio frequency heating was developed. The reactor bed was packed with composite magnetic catalysts, generating heat by the application of RF field at 180-400 kHz. Hydrodynamics in a co-current (gas-liquid) configuration was analyzed and heat transfer rates were determined at temperature ranging from 55 to 100 oC. Then, this concept was extended to a multiple thermal zone configuration. Such configuration allowed achieving desired temperatures in the catalyst beds whereas the inlet and outlet gas temperatures were close to ambient temperature which increases energy efficiency of the system. The overall product yield was increased by 9 times as compared with a single thermal zone configuration. Finally, the scale-up of the micro-trickle bed reactor was performed. The axial scale-up was achieved by repeating a single periodic unit consisting of one heating and one catalytic zone along the reactor length. The catalyst loading can be increased by an order of magnitude following this approach. A radial temperature difference of 2 K was developed in a reactor with an inner diameter of 15 mm. The scale-up by numbering up allows the accommodation of seven parallel tubes inside a single RF coil. It creates a 7 K difference in the average temperature between the central and the outer tubes which results in a 5% difference in conversion. An overall scale-up factor of near 700 is achieved which corresponds to a production rate of 0.5 kg of product/day.