Hydrogenation of dibenzyl toluene - A competing side reaction in three phase methanation

Dibenzyl toluene (DBT), known as Liquid Organic Hydrogen Carrier, is also used as liquid phase in three phase
CO2 methanation. This study explores the hydrogenation of dibenzyl toluene as a side reaction during three
phase CO2 methanation for a range of reactor temperature (𝑇 R = 140 ◦ C to 320 ◦ C) and pressure (𝑝R,abs = 4 bar
to 20 bar). Hydrogenation of DBT and CO2 methanation reaction are competing for hydrogen. Reaction rates
of both reactions are high at high reactor pressure. Regarding reactor temperature, CO2 methanation reaction
rate is increasing with increasing temperature, whereas the DBT hydrogenation reaction rate is decreasing.
This observation can be attributed to competing CO2 methanation and catalyst deactivation at elevated
reactor temperature. The CO2 methanation reaction rate is reduced by competing DBT hydrogenation until
the chemical equilibrium is reached. Catalyst deactivation is also affecting CO2 methanation reaction rates for
𝑇 R > 260 ◦ C.