Intensified Flow Reactor for Continuous Synthesis of High Surface Area Titania Microparticles

Titania microparticles have attracted substantial attention for application in a wide variety of applications due to their moderate band gap and good charge-transfer characteristics. In the past 30 years, numerous synthetic methods, ranging from sol-gel to deposition, have been utilized to synthesize crystalline titania across a wide variety of length scales (nano to micro) and morphologies (hollow and dense) for use in applications including catalysis, electrochemistry, and photovoltaics.¹ However, the aforementioned synthetic strategies are commonly limited to a single morphology and possess substantial hurdles when synthesizing monodisperse titania microspheres, including high polydispersity, size limitations, or the use of complex and time-consuming synthetic methods.

Here we introduce an intensified flow reactor for continuous manufacturing of monodisperse titania microspheres across a wide variety of morphologies that possess excellent surface areas post-calcination, surpassing 360 m²/g.^2,3 The titania microparticles are synthesized utilizing a capillary-based flow-focusing microreactor constructed using easily accessible commercially available components. The microreactor combines in-line UV crosslinking of a photocurable polymer scaffold and the use of a polar aprotic solvent as the continuous phase to enable control of microparticle morphology, crystallinity, and size while using air- and moisture-sensitive titanium precursors. By varying precursor compositions, it is possible to achieve different microparticle morphologies ranging from hollow shells to dense spheres while maintaining anatase crystalline phase at calcination temperatures up to 900 C.

1 T. Zhao et al. Nano Energy, 2016, 26, 16–25.

2 Z. S. Campbell et al. Chem. Mater., 2018, 30, 8948–8958.

3 Z. S. Campbell et al. RSC Adv., 2020, 10, 8340–8347.