Vapor-liquid phase diagrams are Calculated for binary mixtures of diatomic Lennard-Jones molecules using Monte Carlo simulations and the Gibbs-Duhem integration method. We explore the effects of varying the molecular size ratio, intermolecular attraction parameter ratio and binary interaction parameter on the mixture's phase behavior. We plot pressure versus composition vapor-liquid phase diagrams for the binary mixtures O-2-N-2, CO2-C2H6 and N-2-C2H6 at different temperatures. Our results are in good agreement with experimental data, especially away from the critical point. Adding a quadrupole term to the two-center Lennard-Jones (2CLJ) potential model further improves the agreement with experimental data. We also investigate the dependence of Henry's constant on temperature, pressure and binary interaction parameter. (c) 2006 Elsevier B.V. All rights reserved.