Fischer-Tropsch synthesis employing supercritical fluid reaction media offers mass transfer advantages over conventional processes. Data are needed to calculate effective diffusivities in catalyst pores, for which molecular diffusion coefficients in the supercritical media as well as the catalyst porosity and tortuosity are required. The Taylor dispersion technique was used to measure the molecular diffusion coefficients. A tracer response technique was used to measure the effective diffusivities employing 1-octene in supercritical ethane (Pc = 48.8 bar, Tc = 305.4 K) as the model system with an iron-based Fischer-Tropsch catalyst. Measurements were made in the temperature range of 523-543 K and pressure range of 62-144 bar. The results were analyzed by the subtraction of moments method. The precision of the results is within approximately 15%. The average value of tortuosity divided by particle porosity (τ/є p) is (9.72 ± 1.22), while the average value of τ is (6.10 ± 0.766) using the particle porosity set at 0.628.
ASJC Scopus subject areas
- Chemical Engineering(all)