Micromeritics ASAP 2460 - BET Surface Area

Appendix C ASAP 2460 Operator’s Manual
C-8 246-42800-01 - Aug 2013
BET Surface Area
For each point designated for surface area calculations, the BET
2
transformation is calculated as:
where B is in units of g/cm
3
STP.
A least-squares fit is performed on the (P
rel
, B) designated pairs where P
rel
is the independent variable
and B is the dependent variable. The following are calculated:
a.) Slope (S g/cm
3
STP)
b.) Y-intercept (Y
int
g/cm
3
STP)
c.) Error of the slope (S
err
g/cm
3
STP)
d.) Error of the y-intercept (YI
err
g/cm
3
STP)
e.) Correlation coefficient
Using the results of the above calculations, the following can be calculated
BET Surface Area (m
2
/g):
where
CSA = analysis gas molecular cross-sectional area (nm
2
), user-entered on the
Adsorptive Properties window
BET C value:
Quality of the Monolayer (cm
3
/g STP):
B
P
rel
1.0 P
rel
–N
ads 1
-------------------------------------------
=
SA
bet
CSA 6.023 10
23

22414 cm
3
STP
10
18
nm
2
m
2
-----------------------



SY
int
+
-------------------------------------------------------------------------------------------------
=
C
SY
int
+
Y
int
------------------
=
Q
m
1
CY
int
-------------
1
SY
int
+
------------------
==