Multiscale modeling of monolithic sponges as catalyst carrier for the methanation of carbon dioxide

Abstract

Solid sponges provide large surface areas, low pressure drops, and excellent heat transport properties and are thus promising monolithic catalyst carriers. Their potential compared to randomly packed beds at industrial scales, however, is largely unknown. To facilitate scale-up and future simulation studies, we present a 2-d mulstiscale reactor model for catalytic sponges. Therefore, we couple a 2-d pseudo-homogeneous reactor model with a 1-d reaction–diffusion model to explicitly consider heat and mass transfer and diffusional limitations at the catalyst scale. A comparison of simulated temperature profiles with experimental ones during CO₂ methanation at the lab scale demonstrates the validity of the developed model. Further, the results show that it is necessary to include heat and mass transport at the catalyst scale to adequately simulate concentration and temperature distributions in solid sponges although the applied catalyst layers are typically thinner than 100 $\mu$m. The presented model thus allows to obtain insights into the interplay between heat and mass transport at both, the reactor and the catalyst scale, and provides a solid foundation for scale-up and techno-economic studies to assess the performance of solid sponges as catalyst carrier at industrial scales.