Abstract: A rapid and efficient method was developed to determine the carbon number distribution of Fischer-Tropsch wax by high temperature gas chromatography coupled with cold-on-column inlet and flame ionization detector (FID). The experimental parameters, such as column flow, oven temperature program, injection volume and sample concentration, were studied in detailed by using a DB-HT-SimDis column. The optimized GC conditions were as follows: Column: DB-HT-SimDis 5 m×0.53 mm×0.15 μm. Carrier gas: hydrogen at flow-rate of 9.0 mL/min (constant flow); Flame ionization detector (FID) temperature 400 ℃. Combustion gases: hydrogen, 40 mL/min; air, 400 mL/min. Nitrogen as makeup gas, 30 mL/min; Oven temperature program: initial oven temperature 60 ℃, hold 1 min; ramp 1 rate, 10 ℃/min to 240 ℃, hold 1 min; ramp 2 rate, 5 ℃/min to 400 ℃, hold 10 min; Inlet temperature: track oven temperature; Injection volume, 0.5 μL; Sample concentration in heated n-heptane: 0.5%. Under above conditions, the carbon number distribution of Fischer-Tropsch wax between C21 and C101 was analyzed within 60 minutes accurately. The GC resolutions higher than 1.5 and 1.2 were obtained in the ranges of C21 to C74 and C74 to C101, respectively. The linear correlation coefficient value between Ln(W/n) and carbon number in the range of C57 and C101 was 0.999 3 and the chain growth probability (α value) of 0.928 was calculated.

Key words: high temperature gas chromatography, flame ionization detector, DB-HT-SimDis column, Fischer-Tropsch wax, carbon number distribution