Effect of particles size and density on the segregation of catalyst-sorbent mixtures for direct sorption-enhanced DME synthesis: Experimental and mathematical study

Direct sorption-enhanced dimethyl ether synthesis (SEDMES) is a promising process for the production of fuels from CO 2 sources. Using novel technologies, the process can be run exploiting the phenomena of particles segregation in a fluidized bed reactor. However, the knowledge on the solid movement and the segregation patterns is a mandatory preliminary step for the setup of the final application. In this study, we evaluated the impact of particles size and density on the segregation patterns, and we used the Gibilaro and Rowe (GR) model to analytically represent the experimental results. It was observed that the variation of both parameters influences segregation, even though a higher separation degree in a wider operating velocity range was observed when a higher density ratio was induced between the two solids. Through the experimental analysis, five possible bed configurations were identified, and a consideration was made on the aims of the GR model to adjust the mathematical representation to the present case. By considering the bottom portion of the bed as a jetsam-rich phase and not – as previously reported – as a segregated layer, a mass balance on the catalyst allowed to obtain a faithful analytical representation of the experimental segregation patterns. • Small variations in density or particles size ensure segregation in a fluidized bed. • Density ratio has the biggest impact on segregation in binary mixture fluidization. • Higher density ratios ensure segregation over a wider fluidization velocity range. • Segregation models adapted to small-scale systems match experimental patterns. • Jetsam-rich/flotsam-rich phase approach improves segregation pattern predictions.