Experimental and theoretical study of the influence of solvent on asphaltene-aggregates thermo-oxidation through high-pressure thermogravimetric analysis

•Asphaltene aggregate size increases in the order o- < m- < p-xylene.•Xylene isomers have a substantial impact on the aggregation state of asphaltenes.•High asphaltene aggregate size reduces the mass gained by oxygen chemisorption.•Large asphaltene aggregates have low reactivity at higher temperatures.•Understanding the reactivity of asphaltene aggregates promotes alternatives to improve the ISC. This study is focused on the understanding of n-C7 asphaltene-aggregates oxidative behavior under high-pressure conditions. For this aim, different asphaltene model solutions were prepared using three asphaltene concentrations (0.1, 1.0, and 10 wt%) on three xylene isomers. The experimental results revealed that the asphaltene aggregate size increase in the order o-xylene