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Advances in the discovery of novel nanomaterials and their properties have resulted in an increase in their demand. Nanomaterials are gaining increasing importance in multiple fields including catalysis, biomedicine, and energy storage with their market expected to double in the next two years. These applications call for innovative technologies that can produce nanomaterial at high throughputs such that quality obtained at the bench scale is retained. The properties of nanomaterials are highly dependent on the mixing dynamics of their synthesis process. Macromixing in conventional batch nanomaterial syntheses increases the overall mixing time, leading to variability within batches and a wide particle size distribution. These problems can be circumvented by using micro- and milli-fluidic reactors that provide a small mixing time because of their associated micromixing and mesomixing. This work investigates a continuous jet-mixing milli-fluidic reactor for the scalable synthesis of metal and metal-oxide nanomaterials and attempts to expand its applicability to a variety of synthesis conditions.Initially, liquid-phase nanomaterial synthesis under ambient conditions is demonstrated as proof-of-concept using the jet-mixing reactor. Silver nanoparticles (Ag NPs) are used as the test system because of their ease of synthesis and characterization. It is observed that Ag NPs synthesized using jet-mixing have a particle size distribution narrower by 4.5% and a 20% increase in stability as compared to their batch-synthesized counterpart. The jet-mixing reactor also demonstrates material economy by requiring a capping agent concentration that is four times lower than that required in batch.Whereas Ag NPs can be synthesized under ambient conditions, the flow synthesis of nanomaterials that are air-sensitive or have air-sensitive precursors remains a challenge. The scope of jet-mixing is expanded to such systems by developing a process to incorporate inert conditions for pure-phase copper nanomaterial (Cu NP) synthesis. Cu NPs that tend to oxidize readily under ambient conditions are synthesized with >80% phase purity using jet-mixing.Next, multicomponent nanomaterial synthesis is demonstrated using jet-mixing. Pd@TiO2 core-shell nanocatalysts are selected as the test system. These catalysts are known to be highly selective towards hydrodeoxygenation (HDO) because of the microporosity in their TiO2 shell. First, the effect of various parameters on the microporosity is studied in batch to design the jet-mixing synthesis. Next, Pd@TiO2 nanomaterials are synthesized through the batch and jet-mixing syntheses. Jet-mixing results in properties including microporosity and Pd loading that are comparable to the batch-synthesized counterpart. Lastly, Pd@TiO2 obtained from batch and jet-mixing synthesis is tested as a catalyst for the hydrodeoxygenation (HDO) of benzyl alcohol. It is observed that the jet-mixing synthesized material is 100% selective towards the HDO product. Scalable synthesis of heterogeneous HDO-selective Pd@TiO2 is demonstrated using jet-mixing.The flow synthesis of Pd@TiO2 is performed via a “seeded” method in which Pd NPs are pre-synthesized in batch before capping with TiO2 in a single jet-mixer. However, large-scale heterogeneous nanomaterial syntheses would benefit from a fully continuous process over a semi-continuous process. This goal is achieved by adapting the jet-mixing reactor for multi-step syntheses through the design of a `dual’ jet-mixer that is tested as proof-of-concept for gold core silver shell nanoparticles (Au@Ag NPs). Initially, single jet-mixing is used for gold nanoparticle synthesis to compare the properties of nanomaterial synthesized via batch with that obtained from jet-mixing. Next, “seeded” Au@Ag NP synthesis is performed in a single jet-mixer to investigate silver shell capping in flow. Lastly, fully continuous synthesis through dual jet-mixing is done in which gold nanoparticles are synthesized in-situ in the first reactor whereas the silver shell is capped in the second reactor. Successful Au@Ag NP synthesis in a fully continuous process is demonstrated, expanding the synthesis space of the jet-mixing reactor.Overall, the work in this dissertation shows that jet-mixing is a scalable, modular, and versatile millifluidic platform for the synthesis of inorganic nanomaterials under a variety of conditions that also retains or improves properties obtained at the bench scale. |
