A molecular separation method can include: passing a deasphalted oil stream through a reactor containing an active substrate, wherein the catalytic active substrate adsorbs heteroatom species from the deasphalted oil stream and produces a pretreated hydrocarbon feed stream essentially free of 4+ ring aromatic molecules (ARC 4+ species), metal species, and heteroatom species; and chromatographically separating with a simulated moving bed apparatus or a true moving bed apparatus (SMB/TMB) the pretreated hydrocarbon feed stream into a saturate fraction and an aromatics fraction.