Hydrogenation of the Liquid Organic Hydrogen Carrier Compound Monobenzyl Toluene: Reaction Pathway and Kinetic Effects

Abstract

Liquid organic hydrogen carriers (LOHCs) are an interesting option for storing hydrogen through a reversible chemical reaction. The catalytic hydrogenation reaction was studied for the carrier material monobenzyl toluene. GC analysis was used to quantify the components occurring in a complex reaction mixture. It was shown that the hydrogenation reaction proceeds predominantly by stepwise hydrogenation of the aromatic ring. As the molecular structure of monobenzyl toluene is formally the combination of a xylene and a toluene ring, two possible reaction pathways have been evaluated: hydrogenation of the mono‐substituted side ring (toluene) and di‐substituted main ring (xylene). Intermediates for both pathways were detected during the reaction. Concerning the isomeric structure of benzyl toluene, the fastest hydrogenation was observed for the para species. Isomeric mixtures were hydrogenated the slowest.

Hydrogen Production from the LOHC Perhydro-Dibenzyl-Toluene and Purification Using a 5 µm PdAg-Membrane in a Coupled Microstructured System

“…The general structures of the molecules do not change in the course of the reaction. [6,7] Materials 2020, 12, x FOR PEER REVIEW 3 of 15 partially hydrogenated isomers as intermediates, and completely dehydrogenated C6 rings in one molecule. The general structures of the molecules do not change in the course of the reaction.…”

“…The general structures of the molecules do not change in the course of the reaction. [6,7] Figure 2. Schematic drawing of the LOHC system perhydro-dibenzyl-toluene/dibenzyl-toluene and its stable forms with different hydrogenation levels.…”

Hydrogen Storage for Mobility: A Review

“…Dibenzyltoluene is another LOHC which is being studied and evaluated [183,184,185,186,187,188]. It can store up to 6.2 wt % at 7.7 MJ/L of hydrogen [189], and it is a liquid substance at ambient temperature with low water solubility, flammability, and toxicity [190].…”

Hydrogenation of the LOHC Compound Monobenzyl Toluene over ZrO2‐supported Ru Nanoparticles: A Consequence of Zirconium Hydroxide's Surface Hydroxyl Group and Surface Area

“…Although the extended ageing resulted in a larger BET surface area of Ru/ZrO 2 , the hydrogenation activity and Ru dispersion turned out to be in a volcano-shaped dependence on the ageing period. Ru, the cheapest among noble metals, was examined the most active for several LOHC materials including N-ethylcarbazole, [4] H 0 -MBT, [1,5] H 0 -DBT, [1,6] and 2-(n-methylbenzyl)pyridine. Consequently, the hydrogenation activity trend of the present Ru/ZrO 2 was a combined consequence of the surface OH content and surface area of zirconium hydroxide.…”

“…However, less attention has been paid to the latter reaction because the dehydrogenation catalyst suffers more from thermal stress than the hydrogenation catalyst.In this communication we focused on supported Ru catalysts for the hydrogenation of H 0 -MBT (purity: > 99 %, an isomeric mixture as represented in Figure S1). Ru, the cheapest among noble metals, was examined the most active for several LOHC materials including N-ethylcarbazole, [4] H 0 -MBT, [1,5] H 0 -DBT, [1,6] and 2-(n-methylbenzyl)pyridine. [7] The catalytic activity of supported Ru particles was reported to depend largely on the textural and acidic/basic properties of support materials.…”