Enhancement of the Solubility of Alkanes in Hydrogen by Structural Branching

The understanding of mutual solubilities in H2-containing systems is the foundation for improving H2-related processes. This study demonstrates that Gibbs ensemble Monte Carlo simulations successfully predict the mutual solubility of hydrogen-alkane systems over a wide range of conditions (323.2–462.5 K, 1.7–20.3 MPa) with the optimal corrections to the combination rules. We found that the solubility of decane and hexadecane in H2 increases by 2–3.3 times with an increasing number of methyl groups in the alkane (branching). Notably, a decrease in the solubility parameter and an increase in alkane–H2 interactions are the key mechanisms responsible for the enhanced solubility in H2. This study enables the prediction of mutual solubility for a variety of hydrogen–alkane systems and reveals that introducing methyl groups is an effective strategy for enhancing the solubility of compounds in H2 (termed H2-philicity).