Alpha-S Method - Micromeritics ASAP 2460 Operator's Manual

ASAP 2460 Operator's Manual

Alpha-S Method

The alpha-S curve is calculated from the reference isotherm by dividing each quantity adsorbed by the
quantity adsorbed at 0.4 relative pressure.
Q
i
--------- -
a =
i
Q
0.4
where Q is found by linear interpolation.
0.4
A least-squares analysis fit is performed on the (α
able and Q is the dependent variable. The following are calculated:
ads,i
a.) Slope (S cm³/g STP)
b.) Y-intercept (Q
c.) Error of the slope (cm³/g STP)
d.) Error of the Y-intercept (cm³/g STP)
e.) Correlation coefficient
Surface area is calculated as:
A
S
ref
------------ -
A =
Q
0.4
Pore size is calculated as:
Q V
0 mol
------------------------------------ -
3
22414
cm
where V is liquid molar volume from the fluid property information.
mol
246-42800-01 - Aug 2013
cm³/g STP)
0
STP
,Q ) data pairs where α
i ads,i
Appendix C
is the independent vari-
i
C-13