Page 150 - Gas Adsorption Equilibria

136 Chapter 3

4. High pressure adsorption of and on activated carbon NORIT Rl at
298 K-343 K for pressures (p < 50 MPa).
5. Adsorption of sub- and supercritical on MS 5A.

Example 1
Adsorption of natural gas compounds on activated carbon

The sorbent material chosen is activated carbon NORIT R1 EXTRA made
from peat by thermal and chemical activation. To determine its BET surface
the adsorption isotherm (AI) of nitrogen was taken at 77 K. It is
presented in Figure 3.7A. It shows a very steep increase at low pressures
indicating existence of micropores (d < 2 nm) and a slight hysteresis in the
range reflecting mesoporous structures. The
resulting BET surface area is (ISO 9277: 1995). Other
characteristic quantities are given below [3.27], [3.28]:

Elemental analysis given in (%atom):

C 0 N Ca S Si Others
93.7 4.8 0.4 0.2 0.2 0.7 0.3

Structure of C-based active sites given in (%):

-C-O-C- -C=O O=C-O -CX
70 13 6 5 4 2

The activated carbon was delivered by the manufacturer as cylindrical
pellets of length 4 mm and diameter 1 mm having a bulk density of 0.435
kg/l.