Adsorption equilibria of methanol/carbon dioxide mixtures on plain silica particles at 308 K and pressures of 10.1 MPa, 12.7 MPa, 15.1 MPa and 20.1 MPa were measured with the frontal analysis by characteristic points (FACP) method using supercritical fluid chromatography. The data show a bimodal adsorption energy distribution and cannot be sufficiently modeled with a two-dimensional SAFT-VR approach. Therefore, an extension of SAFT-VR is proposed to model adsorption on heterogeneous surfaces and applied to the presented data. It can be described by the extended model with very low ARDs between 1.0% and 2.4%.