Evaluation of industrially applied heat-transfer fluids as liquid organic hydrogen carrier systems.

Liquid organic hydrogen carrier (LOHC) systems offer a very attractive method for the decentralized storage of renewable excess energy. In this contribution, industrially well-established heat-transfer oils (typically sold under trade names, e. g., Marlotherm) are proposed as a new class of LOHC systems. It is demonstrated that the liquid mixture of isomeric dibenzyltoluenes (m.p. -39 to -34 degrees C, b.p. 390 degrees C) can be readily hydrogenated to the corresponding mixture of perhydrogenated an-alogues by binding 6.2 wt% of H-2. The liquid H-2-rich form can be stored and transported similarly to diesel fuel. It readily undergoes catalytic dehydrogenation at temperatures above 260 degrees C, which proves its applicability as a reversible H-2 carrier. The presented LOHC systems are further characterized by their excellent technical availability at comparably low prices, full registration of the H-2-lean forms, and excellent thermal stabilities.