Continuous synthesis of copper nanoparticles using a polyol process in a milli-channel reactor

The physio-chemical properties of metallic nanoparticles are different from their corresponding bulk material. Synthesizing stable zero valent copper nanoparticles is a challenge since they get oxidized easily. This paper discusses both the batch and continuous synthesis of copper nanoparticles using a polyol process in the absence of an inert atmosphere. The nanoparticles were synthesized using copper amine complex as a precursor, ascorbic acid as a reducing agent, and polyvinyl pyrrolidone as a capping agent. UV-Vis spectra confirmed that particles from a continuous synthesis had better Localized Surface Plasmon Resonance (LSPR) peak than those from batch synthesis. At 120 °C, nanoparticles in the continuous process could be synthesized at a residence time of 1 min in contrast to the batch reactor, which needed a reaction time of 4 min. The nanoparticles synthesized were of size 1.5–6 nm. Those synthesized in continuous mode were stable for 10 days as compared to those synthesized in batch mode.