The determination of effective diffusivity by gas chromatography. Time domain solutions

✍ Scribed by Henry W. Haynes Jr.

• Publisher: Elsevier Science
• Year: 1975
• Tongue: English
• Weight: 639 KB
• Volume: 30
• Category: Article
• ISSN: 0009-2509
• DOI: 10.1016/0009-2509(75)80062-5

✦ Synopsis

Time domain solutions applicable to the GC pulse dispersion experiment are presented in the form of dimensionless numerical plots. It is shown that when the particles are nonporous, or diffusion in both the macro-and micropore systems is rapid, a Gaussian peak results. In this case the peak broadening is due to axial dispersion alone. When either the macro-or micropore resistance becomes significant, the peak assumes a skewed shape. The experiment should be conducted under these circumstances if possible.

Selection of the proper particle size to employ in the experiment is important. Large particles should be employed in measurements of macropore diffusion. Small particles enhance the microparticle contribution to peak broadening and measurements of micropore diffusion in amorphous materials should be conducted over crushed samples. With some materials, namely zeolite systems in which strong molecule-pore entrance interactions exist, the tailing may be impossible to determine over crushed particles. This situation can sometimes be improved by using full-size particles.