Author ORCID Identifier
Doctor of Philosophy
In recent years, research has focused on reducing the cost of catalysts in a variety of ways including using less expensive materials, improving the synthetic method, and increasing the catalytic activity, recovery, and recyclability. Typically with nanoparticles, the size, shape, composition, and surface coating have an effect on catalytic activity.1-2 In this work, we focused on reducing the cost of precious metal based catalysts by altering the synthetic methods.
One way to lower the cost of synthesizing precious metal nanoparticles is by debasing the precious metal with a second cheaper more abundant metal. CuPd nanoparticles were synthesized in oleylamine and displayed catalytic activity in several cross-coupling reactions. Due to copper being present in the nanoparticle, a copper halide co-catalyst was not needed for Sonogashira cross coupling to be successful.3 While this method produced reactive catalysts, low product yield hinders its application for industry.
Solution based synthesis of metallic nanoparticles typically require long reaction times and high temperatures, which make large scale production of nanoparticles on an industrial scale difficult.4-5 The use of continuous flow microreactors provides greater control of synthetic parameters, leading to lower batch-to-batch variability and increasing the efficient of heat and mass transfer and have been applied to the synthesis of metals, semiconductors, zeolites, organic compounds, and semiconductors.5-7 To compare continuous flow methods to benchtop reactions, a well-characterized benchtop reaction synthesizing Cu@Ni core/shell nanoparticles was successfully transferred to a flow reactor set-up. Cu@Ni nanoparticles were synthesized using a capillary microreactor in under 1 minute compared to the 1 hour reaction on benchtop with similar properties in a green solvent.2 The Cu@Ni nanocomposites were active towards the Fischer Tropsch reaction.8 2 nm platinum nanoparticles and platinum bimetallic alloys were synthesized in water using a capillary microwave flow reactor. Investigations showed the nanoparticles were activity toward hydrogenation of octene.
With further development, continuous flow synthesis of metallic nanoparticles can be applied to the synthesis of a wide variety of catalysts on an industrial scale. Continuous flow methods provide greater control of reaction parameters, increased safety by reacting smaller volumes of chemicals at a given time, and decreasing the batch-to-batch variability.
© Sarah Emily Smith
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Available for download on Saturday, May 07, 2022