Nanoparticles (NPs) display unique properties due to their high surface area to volume ratios and quantum effects. They offer a multitude of potential applications such as in nanomedicine, catalysis, optics, electronics and sensors. The size, shape and dispersity of the NPs are important, since their properties depend on these parameters. Traditionally batch reactors have been used in NP synthesis. Flow reactors offer some distinct advantages over batch reactors for the manipulation of morphology of NPs such as spatio-temporal separation, allowing the stages of reduction reaction, nucleation and growth to be better controlled. A co-axial flow reactor (CFR) and impinging jet reactor (IJR) which have different hydrodynamics and mixing characteristics have been evaluated for NP synthesis. These reactors are contrasting in that the CFR has slower mixing because of its laminar flow profile, whereas the IJR has mixing time in the order of a few ms. The importance of mixing time as well as manipulation of hydrodynamics at the micro scale is shown through the use of these types of reactors. The link between mass transfer and nanoparticle size and dispersity for the systems tested shows the need for well controlled and efficient mixing. Single and multiphase flow reactors for the synthesis of gold NPs and gold nanoclusters will also be discussed. In this case, a rational reactor design based on overall synthesis kinetics will be demonstrated.
Asterios Gavriilidis received his first degree from Aristotle University of Thessaloniki, Greece and his PhD in Chemical Engineering from the University of Notre Dame, USA in 1993 under the supervision of Prof Arvind Varma. The same year he joined University College London, Chemical Engineering dept. where he is currently Prof of Chemical Reaction Engineering. He has long standing expertise on catalytic reaction engineering, and his group has developed a range of intensified reactors, such as coupled catalytic plate reactors, mesh reactors, rotating disk reactors, membrane reactors for applications in bulk chemicals as well as fine chemicals/ pharmaceuticals. The reactors have been used to perform various types of reactions including catalytic oxidations, hydrogenations, epoxidations, ozonolysis etc. Since 2000 he has been working in microreaction technology and micro process engineering. This work takes advantage of unique properties of miniaturised devices and the dominance of different forces in microscale for process intensification and obtaining information under well-controlled conditions. In this context, his group has developed microreactors, microdistillation and microseparation devices that have been fabricated by lithographic processes. Currently, his group is focussing on the development of microreactors and milli reactors for nanoparticle manufacturing for applications in healthcare (antimicrobial surfaces, cancer hyperthermia treatment, diagnostics), on the development of microreactors for catalyst operando studies and automated microreactor set-ups integrated with MBDoE algorithms for closed-loop kinetic model investigations. He has published >200 papers, he is subject editor for Chemical Engineering Research and Design, Fellow of the IChemE, Chartered Engineer, and UK representative in the Working Party of Chemical Reaction Engineering of the European Federation of Chemical Engineers.
This seminar is compulsory for students registered for course CL 702 or CL 704.