Improving Productivity, Heat Transfer, and Catalyst Stability in the Dehydrogenation of Perhydro Benzyl Toluene through Internal Product Recycling

High Resolution Image Download MS PowerPoint Slide The liquid organic hydrogen carrier (LOHC) technology enables efficient hydrogen storage under ambient conditions by chemically binding hydrogen to organic molecules. Among the various LOHC systems, the perhydro benzyl toluene/benzyl toluene (H12‑BT/H0‑BT) pair stands out due to its low vapor pressure, favorable thermal stability, and high volumetric storage density. Continuous dehydrogenation of H12‑BT in fixed‑bed reactors, however, is typically characterized by rapid evaporation of the LOHC once a significant part of the bound hydrogen has been released. The resulting gas‑phase dehydrogenation suffers from reduced heat transfer efficiency and catalyst wetting. In this study, we introduce a reactor concept that suppresses full LOHC evaporation through an internal recycling of the hydrogen‑lean liquid product. We compare this recycling concept with the classical once-through reaction mode regarding heat demand, heat transfer, hydrogen release productivity, by‑product formation, and catalyst stability. Although the recycling concept exhibits a moderately higher heat demand due to its higher overall amount of LOHC evaporation, it significantly improves heat transfer in the reactor, leading to higher average catalyst bed temperatures. As a result, hydrogen release productivity increases by up to 50%, while by‑product formation remains comparable to the classical concept. Furthermore, the enhanced liquid holdup reduces coke precursor accumulation at the catalyst and markedly improves catalyst stability.