Abstract
A rapid method for analyzing the compositions of various residues and their hydrocracking products was investigateuds ing thin-layecrh romatography (TLC) with flame ionization detection (FID).
As shown in Fig. 1 and Table 1, accurate separation of saturates (Sa), aromatics (Ar), resins (Rs), and asphaltenes (As) could be carried out by means of threestage solvent development using n-hexane, toluene, and tetrahydrofuran. Furthermore, it was found that analytical precision was influenced by the weight of the sample loaded onto the chromarod. As shown in Figs. 5 and 6, when the weight of a sample loaded ranged from 100 to 150μg, scattering was but slight, however, when it was less than 70μg, scattering was substantial.
The following operating procedures were used:
(1) Suspend the rod, which is activated by scanning once before use, for 10 minutes in the humidity tank containing saturated aq. solution of NaNO2.
(2) Spot 1μl of the sample adjusted with toluene to 10wt/vol percent on the rod with a 1μl glass capillary.
(3) Suspend the spotted rod in the humidity tank used in (1) for 10 minutes.
(4) Develop the rod to 10cm after having it suspended developing tank containing n-hexane for 10 minutes.
(5) After drying the rod at 80°C, suspend it in the humidity tank of (1) for 10 minutes.
(6) Develop the rod to 5cm after having it suspended in the developing tank containing toluene for 10 minutes.
(7) After drying the rod at 800°C, suspend it in the humidity tank of (1) for 10 minutes.
(8) Develop the rod to 2.5cm after having it suspended in the developing tank containing THF for 10 minutes.
(9) Dry the rod at 800°C.
(10) After the contents of the individual components have been identified as peak areas from FID, calculate the results of composition analysis.
It was observed that the standard deviation of the FID-TLC method was less than 1wt%. The time required by our method for analysis per 10 samples was about 2 hours which is very much shorter than that usually required by ordinary SARA methods.
