Two-Surface Virial Analysis of Alkane Adsorption on Carbopack C with and without Hydrogen Treatment
✍ Scribed by Chrystal D. Bruce; Thomas R. Rybolt; Howard E. Thomas; Tara E. Agnew; Brandon S. Davis
- Publisher
- Elsevier Science
- Year
- 1997
- Tongue
- English
- Weight
- 137 KB
- Volume
- 194
- Category
- Article
- ISSN
- 0021-9797
No coin nor oath required. For personal study only.
✦ Synopsis
the ratio of energy of high energy sites to low energy sites Second gas-solid virial coefficients for propane, butane, penon the surfaces, and the fraction of solid covered with higher tane, and hexane were found for Carbopack C and Carbopack Cenergy sites or ''hot spots.'' Finally, the gas-solid interac-HT (Supelco Inc.) within the temperature range of 323 to 471 tion energies for the four alkanes were correlated versus K using gas-solid chromatography in the Henry's law region of their boiling points and versus their critical temperatures adsorption. Carbopack C and Carbopack C-HT are both graphidivided by the square root of their critical pressures.
tized carbon black powders. Treatment of Carbopack C with hy-
A set of alkanes was selected to provide nonspecific addrogen at 1273 K converts it to Carbopack C-HT and is believed to remove certain high energy sites or ''hot spots'' from the carbon sorbates. These two surfaces were selected because they surface. These two surfaces provide appropriate model systems to provide a useful comparison of the single-surface and twotest a two-surface virial analysis. Surface areas for both powders surface models in that the treatment of Carbopack C to prowere calculated using a uniform single-surface model and a twoduce Carbopack C-HT removes some of the high energy surface model. Only the two-surface virial model which is based sites from the surface. Therefore, we expect the Carbopack on gas-solid interaction parameters determined by an iterative C-HT to have fewer high energy sites than the Carbopack C.
process and numerical integration gave reasonable areas for the
In our two-surface analysis we would hope that the relative two surfaces: 13.2 and 13.9 m 2 /g for Carbopack C and Carbopack amount of the high energy sites on the two different surfaces C-HT, respectively. The percentage of high energy sites on the agrees with this expectation.
Carbopack C was found to be 2.6% and for Carbopack C-HT was found to be 1.5%. The gas-solid interaction energy for the high Gas-solid chromatography (1, 2) was used to obtain virenergy sites was found to be 1.80 times greater than the correial coefficients in the temperature range 323-471 K. In the sponding value for the low energy portion of the surface. In addi-Henry's law region of adsorption the moles adsorbed are tion, the gas-solid adsorption energies for the four alkane addirectly proportional to the second gas-solid virial coeffisorbates were found to have a linear correlation with their boiling cient, B 2s , for the gas-solid system (3). In turn, B 2s is related points and with the ratio of their critical temperatures divided by to the strength of the interaction between the gas adsorbate the square root of their critical pressures.