Production of Nanostructures Under Ultraturbulent Collision Reaction Conditions - Application to Catalysts, Superconduct
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Production of Nanostructures Under Ultraturbulent Collision Reaction Conditions Application to Catalysts, Superconductors, CMP Abrasives, Ceramics, and Other Nanoparticles Irwin J. Gruverman and Jeffrey R. Thumm Microfluidics Division, MFIC Corporation, 30 Ossipee Road Newton, MA 02464-9101 ABSTRACT The development, operation and applications of a novel continuous chemical reactor system are described. The system, known as a Multiple Stream Mixer/Reactor (or MMR), produces nanoparticles by direct precipitation from two or more reactant solution streams in an extreme energy density, ultraturbulent, collision reaction region. Sensors and a control system are employed to assure constant mixing conditions and desired stoichiometry in the reaction region. The interaction chamber is designed to allow macro-, meso- and micromixing during processing. This allows control of product purity, yield, size, size distribution, and phase purity. Typical nanoparticle diameters in the one to ten nanometer range are often achievable, with tight size distribution. The MMR can be scaled from development quantities to tons/hour for production applications. INTRODUCTION If your objective is uniform nanometer-scale dispersions or suspensions, the history of your starting material limits the properties of your end product. Dispersion/mixing systems cannot create particles smaller than the existing primary crystallites since mixing energy densities do not approach levels required to disrupt covalent or ionic bonds. Only by controlling the history of the starting material can truly predictable nanoparticle preparations be manufactured. A new reactor system allows total control of material history and produces nano-scale structures, which can then be separated, purified and redispersed in a desired medium at the primary structure sizes created. The system is a Multistream Mixer/Reactor (MMR). Reactions of two or more streams of pure starting materials are conducted in an ultraturbulent collision zone, continuously and under MMR control of reaction conditions and reactant stoichiometry. Applications include stable suspensions of insoluble therapeutic actives for injection, fine coatings, catalysts, fine grinding media, ceramics, superconductors, and a myriad of other valuable, unique products. Conventional stirred reactors conduct precipitation reactions on a batch basis at low mixing energy density. Throughput is constrained, products have large (many microns) crystallite sizes, and energy efficiency is poor. In contrast, the MMR is a continuous precipitation device utilizing ultraturbulent mixing. Throughput is high, products have crystallite sizes in the nanometer range, and energy efficiency is high. MMR capital cost and space requirements are many times less than equivalent conventional manufacturing resources, with far more reaction control. We will describe the MMR, its evolution from its Microfluidizer® processor roots and its applications, and discuss two demonstration experimental programs, performed under an ATP grant [1] [2]
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