Effect of light alkanes and aromatics on decalin dehydrogenation over noble metal catalysts: A new strategy for the development of naphthalene-based LOHCs

Abstract

The use of the naphthalene/decalin pair as a liquid organic hydrogen carrier has gained increasing interest due to its high hydrogen loading capacity and industrial availability. However, a major challenge in its application is the fact that naphthalene is a solid at ambient conditions, leading to the solidification of the unloaded organic carrier. To address this limitation, small amounts of light organics, such as monoaromatics or cycloalkanes, can be added. In this study, we investigated the dehydrogenation of decalin over various supported precious catalysts (Pt, Pd, Rh, Ru; supported on both activated carbon and alumina) in a stirred batch reactor at 200 °C. Initial experiments were conducted with pure decalin, and we found that Pt/C provided the best performance. Subsequently, we studied the dehydrogenation of decalin in mixtures with different solvents (cyclohexane, methylcyclohexane, benzene, and toluene in the concentration range of 10–40% of the light hydrocarbon). Our results show that the addition of cycloalkanes did not affect the main reaction, while aromatic compounds exhibited weak inhibition. A Langmuir-Hinshelwood kinetic model has been proposed for predicting this behavior, taking into account the significant inhibitory impacts of naphthalene and, when present, the aromatic additive.