Predicting Vapor Pressure of Heavy Hydrocarbons from Molar Refraction and Its Applications to Petroleum Mixtures

In this paper a generalized relation based on the corresponding states approach and use of molar refraction is proposed for the estimation of vapor pressure of pure hydrocarbons from C1 to C100. The hydrocarbons are divided into three groups of n-alkanes, n-alkylcyclohexanes, and n-alkylbenzenes from the paraffinic, naphthenic, and aromatic families. The method is also extended to undefined petroleum mixtures using bulk measurable properties, and unified methods are proposed for the calculation of input parameters from measurable properties of the mixture. The AAD for the proposed method for pure hydrocarbons (C1−C100) and for temperature range of T r = 0.4 to the critical point (ca. 91−968 K) for 1300 data points is 1.85% while from other available methods in the literature this error is about 24%. When evaluated against petroleum fractions the proposed method produces data slightly more accurate than the existing methods recommended specifically for petroleum mixtures. Application of the proposed method to vapor pressure of crude oil is also demonstrated.