Experimental and Numerical Study of the Ultrasonic Atomization Pyrolysis Process toward Mass Production of Photocatalysts

Ultrasonic atomization pyrolysis (UAP) is an effective method for the mass production of micro-/nano-photocatalysts; however, studies on particle-flow behaviors and the collection efficiency were seldom reported, which are very important for its scale-up and industrialization. In this study, a computational fluid dynamics model was developed to simulate the UAP process. Experiments were carried out via a self-designed UAP setup to validate the developed model. A two-way coupling discrete phase model considering particle collision and breakage was employed to investigate the influence of operating conditions (for example, carrying gas flow rate, precursor concentration, ultrasonic frequency, particle injection rate, and temperature) on the collection efficiency and particle-flow behaviors. Effects of particle polydispersity were also studied based on the developed model. Finally, three types of UAP reactors were designed based on the developed model, and the results suggested that a T-shape reactor possessed higher particle collection efficiency. This study could help to understand the particle-flow behaviors inside the reactor, and the developed model could serve as a tool to optimize the design and operation of the UAP reactor toward large-scale production of photocatalysts.