(693g) Impact of Particle Shape and Orientation on the Intraparticle Physicochemical Phenomena of Catalytic Particles

Optimising fixed bed chemical reactors requires a deep understanding of the interconnected nature of the bed structure with its heat and mass transfer profiles. For this, Computational Fluid Dynamics (CFD) models play a key role, especially when directly coupled with experimental setups. In our previous work, the internal structure of laboratory-scale catalytic beds, consisting of particles produced by sieving, was generated and analysed through computed tomography scans [1]. The beds consisted of a wide range of particle sizes, shapes, and orientations, creating a highly polydispersed structure, which was significantly different than that formed by monodispersed spheres [1]. By meshing and simulating the flow through a section of these beds, significant local velocity and pressure gradients between neighbouring pores were observed [2].

Due to their complexity, a fundamental understanding of polydispersed beds has not been reached. This necessitates studies at the individual particle scale, focusing on particle shape and orientation. In the conference, catalytic particles of various shapes are placed at different orientations with regards to the incoming flow, Fig. 1, and the physicochemical phenomena around and within them are resolved. Orientation determined the exposed surface area of the particle, and how the flow is distributed around it. Specifically, convection’s impact was driven by the particle’s orientation, affecting the pressure and temperature profiles, and introducing significant local intraparticle temperature gradients which modified the reaction rate. Orientation also drove the intraparticle diffusion rate, either restricting or enhancing it, and thus the particle efficiency factor. These observations yield valuable insights into the association of particle form with the involved physicochemical phenomena, advancing reactor engineering.

[1] S. Kyrimis et al., Advanced Powder Technology, vol. 34, no. 2, p. 103932, 2023

[2] S. Kyrimis et al., Proceedings of the 10th International Conference on Fluid Flow, Heat and Mass Transfer (FFHMT '23) (Under review), 2023