Simulated distillation of high-boiling petroleum fractions by capillary supercritical fluid chromatography and vacuum thermal gravimetric analysis

Capillary supercritical fluid chromatography (SFC) and vacuum thermal gravimetric analysis (VTGA) were utilized for simulated distillation (SIMDIS) of high-boiling petroleum fractions obtained by short-path vacuum distillation. The SFC method covers the approximate boiling range of 250-1400/sup 0/F. Under the present conditions, even 42% of a nondistillable, nondeasphalted residue was recovered from the column at a calculated 1426/sup 0/F atmospheric equivalent boiling point. The influence of temperature and pressure on resolution and retention was studied. SFC-SIMDIS was performed by using linear pressure programming at 100/sup 0/C, as compared to 400/sup 0/C+ temperatures required for comparable samples when capillary gas chromatography (GC) is employed. Polysiloxane-coated, 50-..mu..m-i.d. columns permitted fast analyses (30-min run time) yet maintained adequate resolution for SIMDIS analysis. VTGA-SIMDIS data of samples in the 500-1000/sup 0/F boiling range yielded excellent correlation with actual distillation data. However, thermal analysis revealed decomposition of samples at temperatures exceeding ca. 370/sup 0/C. The validity of the SFC method was demonstrated by comparing SFC-SIMDIS data with those obtained by GC and VTGA.