Catalyst shape matters: Influence of catalyst shape on reactor performance in hydrogen release from perhydro benzyltoluene

This study investigates how the geometrical catalyst pellet shape affects the reaction performance in hydrogen release from the liquid organic hydrogen carrier (LOHC) compound perhydro benzyltoluene (H12-BT). A catalytic distillation (CD) reactor setup serves as experimental platform for our investigation of different catalyst pellet shapes in H12-BT dehydrogenation. CD facilitates H2 release from H12-BT at lower temperatures enabling heat integration of this endothermic process with low temperature waste heat sources. At 200 mbarabs and temperatures below 250 °C, we achieved complete dehydrogenation of H12-BT for the first time. The CD setup enhances the H12-BT concentration in the catalyst bed, but also introduces challenges such as the risk of flooding. Our research introduces a ribbed-ring catalyst shape for the specific purpose of H12-BT dehydrogenation that significantly outperforms the commercial reference catalyst. The ribbed-ring catalyst achieves a 2.4-fold increase in H2 release rate without additional by-product formation and eliminates the need for a gas channel in the CD thus facilitating scale-up. Liquid phase dehydrogenation (LD) experiments revealed that the superior performance of the ribbed-ring catalyst is mainly due to the increased geometric ratio of outer surface area to pellet volume. ... mehrOur findings underscore the importance of a tailored catalyst pellet geometry in optimizing fixed-bed reactors for hydrogen release reactions from LOHC systems and other reactions with significant volume expansion.