Predictive method of hydrogen solubility in heavy petroleum fractions using EOS/GE and group contributions methods

Hydrogen solubility in heavy petroleum fractions was modelled with Peng-Robinson cubic equation of state combined with the UNIFAC solution model (EoS/GE) through a modified Huron-Vidal mixing rule (MHV1). As critical properties and molecular structure of heavy petroleum fractions are entering parameters in this thermodynamic model, the thermodynamic characterization procedure by contribution of functional groups proposed by Carreón-Calderón et al. (2012) was taken as starting point in order to develop a predictive method for estimating hydrogen solubility in such fractions. The functional groups considered in the original work were reviewed and modified, improving predictions and avoiding adjustment of model parameters. Besides, a procedure of mass distribution for the hydrogen-carbon ratio (HCR) of the petroleum fraction is proposed so that the hydrogen solubility can be estimated when more than one heavy petroleum fraction is present. This approach was tested with twelve heavy petroleum fractions in a wide range of pressure and temperature. These fractions include coal liquids, refinery products and a bitumen from Athabasca. The total average deviation was about 15%.