Developing a robust large-volume prototype sonochemical reactor for CO2 reduction reactions

PI: Kwan, James

Department: Engineering Science

Cement production generates approximately 10% of global carbon dioxide (CO2) emissions. Converting this CO2 to valuable products presents a substantial positive impact for the environment and provides economical avenues for CO2 to enter a circular economy. Yet, conventional CO2 reduction reactions (CO2RR) requires high temperatures and pressures and hydrogen gas, resulting in an unsustainable process. Sonochemistry may provide an alternative route. Sonochemistry employs sound to generate bubbles that rapidly expand and contract (i.e., cavitation), leading to novel chemical reactions. Unique chemistries are possible because the bubbles created by ultrasound can reach temperatures above 5000°C during compression, which breaks molecular bonds under ambient bulk temperatures. Furthermore, sonochemistry can be powered by sources of renewable energy and is considered a 'green' chemical process. However, sonochemistry remains underexplored regarding potential chemistries and applications owing to low yields, slow reaction rates, and large energy demands. We demonstrated a novel sonochemical reactor (SonoCYL) that uses cylindrically converging ultrasound waves to nucleate cavitation and amplify both the speed and energy efficiency of sonochemistry. Yet, SonoCYL is a small-scale benchtop prototype model. There are also no standard practices to confidently compare different sonochemical reactors, limiting the ability to validate the performance of the SonoCYL. The barriers of this technology are: 1) device scale, 2) operational optimisation, and 3) standardised validation practices. To address these barriers, we aim to deliver a robust 'turn-key' sonochemical reactor with methods to validate and compare its performance using CO2RR as a use-case study. Delivering this objective will be the achieved through three Work Packages (WPs): 1) produce a pilot scale reactor using an array transducer, 2) validate the performance of the reactor, and 3) make useful chemicals from CO2.