The influence of outgas conditions and temperature on the adsorptive properties of two aluminas Alon-c and Al6sG were studied using adsorption isotherm measurements. Alon-C and Al6SG were characterized using X-ray powder diffraction, thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and BET nitrogen surface areas. Some of these techniques were applied to two other aluminas but no isotherm data was obtained. Isotherm data and techniques applied to each alumina are summarized in tabular form

Bailey, R. R.

Wightman, J. P.

English

NASA Technical Reports Server

General Disclaimer 
One or more of the Following Statements may affect this Document 
 
 This document has been reproduced from the best copy furnished by the 
organizational source. It is being released in the interest of making available as 
much information as possible. 
 
 This document may contain data, which exceeds the sheet parameters. It was 
furnished in this condition by the organizational source and is the best copy 
available. 
 
 This document may contain tone-on-tone or color graphs, charts and/or pictures, 
which have been reproduced in black and white. 
 
 This document is paginated as submitted by the original source. 
 
 Portions of this document are not fully legible due to the historical nature of some 
of the material. However, it is the best reproduction available from the original 
submission. 
 
 
 
 
 
 
 
Produced by the NASA Center for Aerospace Information (CASI) 
https://ntrs.nasa.gov/search.jsp?R=19760005065 2020-03-22T17:42:27+00:00Z
SEMI-ANNUAL REPORT
Interaction of Hydrogen Chloride with Alumina
by
R. R. Bailey
James P. Wightman
(NASA-CE-1457C8) INTERACTION OF HYDROGEN	 N76-12153
CHLORIDE WITH ALUKIXA Semiannual Repert
(Virginia Polytechnic Inst. and State Univ.)
12 p HC $3.5C	 CSCL 07D	 Onclas
G3/25 01979
Prepared for
National Aeronautics and Space Administration
December, 1975
Grant NSG 1195
NASA-Langley Research Center
Hampton, Virginia 23665
Space Applications and Tecnology Division
Gerald L. Pellett
Chemistry Department
Virginia Polytechnic Institute and State University
Blacksburg, Virginia 24061
DEC X75
RECEIVED C
NASA M FAUN R
MM BRA" ¢4'
1A. INTRODUCTION
Research prior to December, 1975 has primarily concentrated on an
investigation of the adsorption behavior of two aluminas, Alon-C (gamma
form) and A16SG (alpha form). The influence of outgas conditions and
temperature on the adsorptive properties of these two aluminas have been
studied using adsorption isotherm measurements. Alon-C and A16S G have been
characterized using X-ray powder diffraction, thermogravimetric analysis
(TGA), scanning electron microscopy (SEM) and BET nitrogen surface areas.
Some of these techniques were applied to two other aluminas but no isotherm
data has been obtained. Studies using transmission infrared spectroscopy
are now beginning. Table I summarizes the isotherm data and techniques
applied to each alumina.
B. CHARACTERIZATION TECHNIQUES
Alon-C, a high surface area alumina was obtained from Cabot Co.,
Boston, Mass. It is a fumed alumina made by the hydrolysis of aluminum
chloride in a flame process, similar to that described by Fricke and Jockers(l).
An X-ray powder diffraction exhibited diffraction lines at 1.98 and 1.39 kX
characteristic of -y-Al 203 . The BET surface of 93.5 ± 0.5 m2/g for Aloe-C
was determined by low temperature nitrogen adsorption. Therm gravimetric
analysis (TGA) of Alon-C, because of a lack of sensitivity, did not show
water loss from the Alon.
Scanning electron micrographs were obtained of Alon-C before and
after exposure to 20 torr of hydrogen chloride. Micrographs at 5000 X
magnification show the effect hydrogen chloride has on the texture of the
alumina. The degree of roughness of the alumina decreases after HC1 exposure.
t
1I
1
i
2
2. Al6SG
An X-ray powder pattern of A16SG showed lines characteristic of an
alpha alumina. The BET surface area of A16SG is 8.16 ± 0.2 m2/g. SEM
experiments on A16SG, showed the particle size to 6e larger than that of
Alon-C, however, the two aluminas have similar texture. Again a significant
change is seen in the surface roughness of the alumina after exposure to 20
torr of hydrogen chloride. Thermogravimetric analysis of A16SG, like that
of Alon-C showed no weight loss due to water desorption.
3. Other Aluminas
Two gamma aluminas were prepared by heating two different aluminum
trihydroxides obtained from Alcoa. The y-alur,ina prepared by heating
Alcoa's C-31 coarse at 6000C for 6 hrs. show the same two X-ray diffraction
lines as Alon-C. A BET N2 surface area of this preparation was taken. No
other characterization techniques have been performed on the alumina.
No X-ray powder pattern was obtained on a sample of Hydral 710, an
aluminum trihydroxide, after the heat treatment to transform it to a y-alumina.
Because of its small particle size less than 2 microns, it does not easily
undergo transition to the y-form. BET surface areas obtained before and after
the heat treatment were markedly different. Hydral 710 had a surface area
of 3.75 m2/g and Hydral 710 after heating at 600 O for 6 hours showed an in-
crease to 170.2 m2/g.
F	 3
C. ISOTHERM MEASUREMENTS
1. Experimental
Adsorption measurements were made manometrically in a constant volume
apparatus with a base pressure of 10-5 - 10-6 torr. Prior to adsorption, the
alumina sample was dried in situ under vacuum for a few hours at varying
temperatures. The HC1 gas was of reagent grade, and the pressure of the test
gas (HCl or H2O vapor) was varied to develop an isotherm.
2. H2O/Alon-C
Adsorption of H 2O on Alon-C was used as a criteria to study the reproduc-
ibility of the alumina surface as a function of outgas temperature and the
time of outgassing. No time dependence was found, but the temperature of the
E	 pretreatment was critical in defining the adsorption capacity of Alon-C for
H2O.
Isotherms of H 2O on Alon-C were taken after outgassing at 80° and 400 0 ,
the 400° outgassed sample adsorbing significantly more water. Desorption
experiments show the isotherm to be reversible. Comparison of the H2O sur-
face area obtained at these outgas temperatures and the N 2 BET surface areas
gives an indication of the a.aree of hydrophilicity of the Alon-C surface.
100% reversibility was found fcr the H2O adsorption at 40
0
 and 500
 .
3. H2O/A16SG
Adsorption of water vapor on the a-alumina (A16SG) was found to be sensi-
tive to the outgas temperature. 40° isotherms taken at a series of outgas
temperatures from 80° - 750
0
C showed successive increases in BET water surface
area indicating a change in degree of hydrophilicity of A16SG. After outgassing
at 400°C and H2O area was the same as that for the BET N 2 area, a possible
4indication of the removal of all molecular water (hydrophobic site) from
the A16SG. A comparison of 11 20 adsorption on Alon•C and A16SG is shown in
Figure 1. A16SG is more adsorptive than Alon-C after outgassing at 400°C.
i	 4. HC1 Alon-C
T1- 1
Hydrogen chloride adsorption at 0, 40, 500
 on Alon-C shows no significant
temperature dependence. Readsorption measurement, where HO is pumped away
from the alumina show the hydrogen chloride adsorption on Alon-C is 75% irre-
versible.
j
Sample pretreatment, as shown in Figure 2, greatly affects the adsorp-
tion capacity of Alon-C for HC1.
5. HC1/A16SG:
Isotherms for HC1/A16SG has been obtained at 40° for A16SG after out-
gassing at 80° and 400°C. Again the temperature of outgassing affects the
adsorptive properties of the alumina. Irreversibility of HCl adsorption is
seen on A16SG using readsorption experiments. Fig. 3 shows a comparison
between HC1 adsorption on Alon-C and A16SG after outgassing at 400°C. A
difference in the adsorptive behavior of these two alumina phases is evident
at 400°C, outgassing at 80°C shows similar behavior but the effect is not
as pronounced, Fig. 4.
D. I. R. STUDY
An infrared study of the aluminas, to determine the nature of the
adsorbed species after HCl adsorption and the nature of the different alumina
surfaces has just commenced. An infrared cell has been constructed which is
capable of heating the alumina sample in vacuum to outgas temperature up to
°800C.
5Some difficulty has been encountered in pressing the alumina into
transparent disk for transmission infrared measurements. Alon-C can be
pressed into disks and infrared measurements are now underway.
Spectra of Alon-C and A16SG without a pretreatment have been obtained
in nujol mulls.
6REFERENCES
1. R. Fricke and K. Jockers, Z. Anorg. Chem. 263 3 (1950).
2. K. Werfers and G. M. Bell, Technical Paper No. 19, Aluminum Company
of America, 1912.
if
_
O
= a, pE Ln
a^
f-
E O O O O
_--- i O O O OOJ d' ^ tl'f of
- r =
- 4
r- O
- V N O
t b O O a O
o
O^ W O 000
^ ^O
. E
t
1i a O
E CD
4
0
E.^ O O O O
a, 0 0 0 0
.c -d' v Ln qct
C) 4J
1
Nb O O O O
= 7 ^ d
O
0)
- x xH
F--
O i
cr Q
•r X X X X
Wt
U co
Q)
c
O f
•r W X x
+> V)
bN
.r
i
OJ C
_- a-► O
10 Rf
V
4-
•r X X XM
roi
X
0
c
v CV)
7 C V/ i
r _O 10 U Z7
Q S
1
Q Q ?-
r M
w
V
C
C9
C N
O ^C
Q Q
O
N r
uib
m
41
7
O
U
O
O
O
L
47
41
wa
L w
L r
O Q
4
v O
d. N
S
V
C
to
U
i
C
O
Q
O
^	 N
S
4-
O
C
O
L
OU
.
r+
4J
L
m
1	 •^
LL
(vujwnld Zw/OZN S8 lOw ) 5Ol X N
IO
O
0^
1-20'r
^
r-I ^
Go
41
L
O
41
L.	 4J
4j 0
41
4-
4-
41
O
C4
pf
LL
0
6n
0
C)
c"	 CY
( u ON 6 /13H O LOW ) SOL x N
0
eq
CD	 ko	 Wt
Vu twn LV tw /LJH O L OW 901 X _N
N O
q I
cl
U
l0	 O
^S	 d
r	
TiuTUnTV .w/I:)n OTOW 101 X N
ON
co
r-
tD
r-
v
N
r6
Q1
4J
C3
O
O
co
N Lr-	 d
4-
a
c^N
tp
d
O -O
C
ee
V
C
_O
d
O C
O
O
O
Ln
41
b
i.i
tr	 =
O
C
O
aL
O
NV
d
L
7
01
N


Interaction of hydrogen chloride with alumina

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server