Evaluation of industrial aromatic oils as potential hydrogen carriers: Study of the hydrogenation step

Abstract

Industrial organic streams (oils) with high concentration of aromatics compounds are present in different carbochemical and petrochemical processes. These aromatic compounds are potential hydrogen carriers through hydrogenation-dehydrogenation cycles. For this purpose, catalytic hydrogenation of three different aromatic oils using conventional hydrogenation catalysts is considered in this work. Two oil samples (petrochemical Oil A and carbochemical Oil B) enriched with polyaromatic compounds, along with a manufactured oil of petrochemical origin (SolvessoTM 200), were hydrogenated using Pt/γ-Al2O3 and Pd/γ-Al2O3 catalysts. The study aims to work under mild conditions to avoid secondary reactions and cracking, which is important for using these oils as potential LOHCs. The methodology involved using a stainless-steel autoclave reactor and analysing the composition of the oils and reaction products using gas chromatography and mass spectrometry. Diaromatic compounds were found to be the most reactive, reactant conversion depending on the catalyst and reaction temperature. However, the presence of tri and tetra-aromatic compounds hinder the reaction. Moreover, nitrogenated aromatic compounds are extremely reactive at these conditions. Comparison of SolvessoTM 200 with benzyltoluene, an established LOHC, resulted in promising results. Thus, both Oil A and B, after a purification step, would have interesting qualities to be used as LOHCs with the added advantage of its low price.