U.S. patent application number 10/913802 was filed with the patent office on 2005-01-27 for boehmitic aluminas and high-temperature stable, high-porosity, pure-phase aluminium oxides obtained therefrom.
Invention is credited to Bohnen, Frank Michael, Glockler, Reiner, Juhl, Jens, Meyer, Arnold, Noweck, Klaus, Schimanski, Jurgen.
Application Number | 20050019249 10/913802 |
Document ID | / |
Family ID | 7877491 |
Filed Date | 2005-01-27 |
United States Patent
Application |
20050019249 |
Kind Code |
A1 |
Noweck, Klaus ; et
al. |
January 27, 2005 |
Boehmitic aluminas and high-temperature stable, high-porosity,
pure-phase aluminium oxides obtained therefrom
Abstract
This invention relates to crystalline boehmitic aluminas the
crystallites of which exhibit unusual dimensional differences in
the space directions 020 and 120. This invention further relates to
a method for preparing such aluminas and the follow-up products
obtained therefrom by calcination.
Inventors: |
Noweck, Klaus; (Brunsbuttel,
DE) ; Schimanski, Jurgen; (Brunsbuttel, DE) ;
Juhl, Jens; (Itzehoe, DE) ; Bohnen, Frank
Michael; (Brunsbuttel, DE) ; Glockler, Reiner;
(Brunsbuttel, DE) ; Meyer, Arnold; (St.
Michaelisdonn, DE) |
Correspondence
Address: |
C. James Bushman
Browning Bushman
Suite 1800
5718 Westheimer
Houston
TX
77057
US
|
Family ID: |
7877491 |
Appl. No.: |
10/913802 |
Filed: |
August 6, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10913802 |
Aug 6, 2004 |
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09529484 |
Jun 9, 2000 |
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6773690 |
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Current U.S.
Class: |
423/625 |
Current CPC
Class: |
C01F 7/02 20130101; C01P
2006/14 20130101; C01P 2002/60 20130101; C01F 7/441 20130101; C01P
2006/16 20130101; C01P 2006/17 20130101; Y10T 428/2982 20150115;
B01J 21/04 20130101; C01P 2002/70 20130101; C01F 7/448 20130101;
C01F 7/447 20130101; C01P 2002/72 20130101; C01P 2006/12
20130101 |
Class at
Publication: |
423/625 |
International
Class: |
C01F 007/02 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 14, 1998 |
DE |
19836821.6 |
Claims
1-12. (cancelled)
13. A composition comprising a crystalline boehmitic alumina having
a crystallite size that, determined on the 020 reflex in nm, is
larger than the measured crystallite size determined on the 120
reflex reduced by 1.5 nm.
14. The composition of claim 13, characterized in that the
crystallite size determined on the 020 reflex in nm is larger than
the measured crystallite size determined on the 120 reflex reduced
by 0.5 nm.
15. The composition of claim 14, characterized in that the
crystallite size determined on the 020 reflex in nm is larger than
the crystallite size determined on the 120 reflex in nm.
16. The composition according to any one of claims 13, 14, or 15,
characterized in that the crystallite size determined on the 020
reflex is from 10 to 50 nm.
17. A method of preparing crystalline boehmitic alumina according
to any one of claims 13, 14 or 15, characterized in that
aluminium-oxygen compounds are exposed to long-time hydrothermal
aging in the presence of water at 60 to 240.degree. C. for at least
10 hours.
18. A composition comprising pure-phase aluminium oxide prepared
from a crystalline boehmitic alumina according to any one of claims
13, 14 or 15 by thermal treatment.
19. The composition of claim 18, characterized in that the
aluminium oxide is present in the theta or delta phase.
20. The composition according to any one of claims 18 or 19,
characterized in that after thermal treatment by calcination at
1,200.degree. C. for 3 hours the aluminium oxide has a surface of
greater than 60 m.sup.2/g.
21. The composition according to any one of claims 18 or 19,
characterized in that the aluminium oxide has pore volumes of
greater than 0.6 cm.sup.3/g determined by the mercury penetration
method in the pore radius range of from 1.8 to 100 nm.
22. The composition of claim 18, wherein said thermal treatment
comprises calcination at a temperature of from 800 to 1500.degree.
C. for at least 0.5 hour.
Description
[0001] This invention relates to crystalline boehmitic aluminas the
crystallites of which exhibit unusual dimensional differences in
the space directions 020 and 120. This invention further relates to
a method for preparing such aluminas and the follow-up products
obtained therefrom by calcination.
[0002] The structural relations of the various aluminium oxides and
aluminium hydroxides are very complex. Main distinctions are made
between .alpha.-Al.sub.2O.sub.3 (corundum), .alpha.-AlO(OH)
(diaspore), .alpha.-Al(OH).sub.3 (occasionally also termed
.beta.-Al(OH).sub.3, bayerite, or bauxite dihydrate),
.gamma.-Al.sub.2O.sub.3, .gamma.-AlO(OH) (boehmite), and
.gamma.-Al(OH).sub.3 (occasionally also termed
.alpha.-Al(OH).sub.3, gibbsite, hydrargillite). In addition, there
exist numerous modifications thereof, particularly modifications of
different aluminium oxides obtained by thermal degradation of the
aluminium hydroxides or aluminium oxide hydrates. For instance, it
is generally believed that boehmitic alumina will undergo the
following conversion under the influence of temperature:
Boehmite.fwdarw..gamma.(gamma)-Al.sub.2O.sub.3.fwdarw..delta.(delta)-Al.su-
b.2O.sub.3.fwdarw..theta.(theta)-Al.sub.2O.sub.3.fwdarw..alpha.(alpha)-Al.-
sub.2O.sub.3
[0003] In literature references there are no standardized
designations for the various aluminium oxides, aluminium oxide
hydrates (occasionally also termed aluminium oxide hydroxides), and
aluminium hydroxides, particularly with respect to the preceding
Greek characters. The term `boehmitic aluminas` as used herein
comprises boehmitic and pseudo-boehmitic aluminas.
[0004] Boehmitic aluminas are known. High-purity boehmitic aluminas
can be prepared for example by controlled hydrolysis of aluminium
alkoxides. The resultant aluminium hydroxide hydrogels crystallize
for example in the form of the rhombic aluminium oxide hydrate
crystallite (.gamma.-AlO(OH), boehmitic alumina).
[0005] DE 38 23 895-C1 discloses a process for producing boehmitic
aluminas with pore radii which can be adjusted in a controlled way
from 3 to 100 nm. According to said process, the boehmitic aluminas
are subjected to hydrothermal aging at a steam pressure from 1 to
30 bar (corresponding to a temperature from 100 to 235.degree. C.)
for 0.5 to 20 hours with agitation at a peripheral velocity from 1
to 6 s.sup.-1. Such aluminas and the boehmitic aluminas produced by
other processes have crys-tallite sizes (measured on the 020
reflex) which are always smaller by at least 2 nm compared to the
crystallite sizes measured on the 120 reflex. In U.S. Pat. No.
3,898,322, too, a process for producing hydrothermally aged alumina
suspension is described. According to said process, the aqueous
aluminium hydroxide/aluminium oxide hydrate suspension obtained by
hydrolysis of the aluminium alkoxides is subjected to hydrothermal
aging at room temperature for 2 to 60 hours.
[0006] It is an object of the present invention to provide
boehmitic aluminas having unusual morphologies. It is a further
object of this invention to provide aluminium oxides with unusual
high-temperature stabilities and, furthermore, with extraordinarily
large surfaces and pore volumes after calcination.
[0007] The problem is solved by crystalline boehmitic alumina with
a crystallite size measured in nm on the 020 reflex which is larger
than the crystallite size which is smaller by 1.5 nm, preferably
0.5 nm, measured on the 120 reflex. It is particularly preferred
that the crystallite size measured in nm on the 020 reflex be
larger than the crystallite size measured in nm on the 120
reflex.
[0008] It is a further object of the present invention to provide
methods for preparing the crystalline boehmitic aluminas of the
instant invention.
[0009] The starting compounds employed for preparing the
crystalline boehmitic aluminas of the present invention are
conventional (i.e. crystalline, partially crystalline, or
amorphous) aluminium-oxygen compounds, such as aluminium oxide
hydrates, aluminium hydroxides, or mixtures thereof with aluminium
oxides, preferably conventional pseudo-boehmitic and/or boehmitic
aluminas. When using commercial aluminium-oxygen compounds produced
by other processes, or when the boehmitic alumina is not produced
and is readily employed, for example as a hydrogel, it is preferred
that the aluminium-oxygen compounds be subjected to grinding prior
to aging according to this invention.
[0010] The starting compounds are aluminium oxide hydrates (or
aluminium oxide hydroxides) which are preferably prepared by
hydrolysis of aluminium alkoxides obtained from C.sub.1 to
C.sub.24+ alcohols or mixtures thereof. The aluminium alkoxides can
be prepared for example by the Ziegler process.
[0011] The aluminium alkoxides are hydrolyzed in an aqueous
environment. Generally, the hydrolysis can be performed in a
temperature range from 30 to 150.degree. C., preferably 60 to
100.degree. C. The resultant aluminium oxide hydrate suspension is
then separated from the aqueous alcohol phase. The alumina-water
phase may contain for example alumina hydrate with an
Al.sub.2O.sub.3 content from 5 to 12 wt. %, preferably 10 to 11 wt.
%.
[0012] The aluminium-oxygen compounds employed as starting
materials may also originate from natural resources or can be
produced by other processes, e.g. the amalgam process.
[0013] The crystalline boehmitic aluminas of the present invention
can be prepared by long-time hydrothermal aging of oxygen compounds
of the aluminium, particularly aluminium oxide hydrates, in the
presence of water at temperatures from 60 to 240.degree. C.,
preferably 70 to 160.degree. C., most preferably 70 to 110.degree.
C. for at least 10 hours, preferably at least 20 hours, most
preferably at least 24 to 70 hours or 30 to 60 hours. It is
desirable to keep the shear stress on the aluminium oxide hydrate
suspension low during the production. The term `low shear stress`
used herein means the shear stress caused by an agitator, e.g. a
propeller agitator, running at a peripheral velocity of 0.5 to 3
m/s. The particle size of the aluminium oxide hydrates in the
suspension is preferably in the range from 1 to 12 microns, most
preferably from 6 to 12 microns.
[0014] According to another embodiment of the present invention,
the crystalline boehmitic aluminas of this invention can be
prepared by hydrothermal aging in the presence of water and at
least bidentate, preferably at least tridentate bases, which are
preferably nitrogen bases, and at temperatures from 30 to
240.degree. C., preferably 70 to 160.degree. C., for 0.5 to 170
hours. Examples thereof are diethylene triamine, dipropylene
triamine, triethylene tetramine (triene), tetraethylene pentamine
(tetrene), and pentaethylene hexamine (pentrene).
[0015] According to yet another embodiment of the present
invention, the crystalline boehmitic aluminas of this invention can
be prepared by long-time hydrothermal aging in the presence of
water and metallic or nonmetallic oxides, or oxide hydrates, except
for aluminium oxide or aluminium oxide hydrates, and water at 40 to
240.degree. C., preferably 70 to 160.degree. C., for at least 8
hours, preferably 16 to 170 hours, most preferably 32 to 170
hours.
[0016] Preferably, said metallic or nonmetallic oxides or oxide
hydrates are those of silicon, zirconium, titanium, lanthane,
and/or boron. Examples thereof are SiO.sub.2, ZrO.sub.2, TiO.sub.2,
and B.sub.2O.sub.3. Such oxides are added in quantities from 0.1 to
5 wt. %, preferably 0.2 to 2 wt. %, referring to
Al.sub.2O.sub.3.
[0017] It is preferred that the crystalline boehmitic aluminas of
the present invention or the aluminium oxides prepared therefrom be
free from any foreign atoms, particularly other metal atoms
(including silicon and phosphorus), i.e. said materials should
exclusively consist of aluminium, oxygen, and/or hydrogen in
quantities of greater than 99 atom %, preferably greater than 99.9
atom %.
[0018] Preferably, the crystalline boehmitic aluminas of the
present invention, independently of one another, have the following
characteristics: pore volumes of greater than 0.8 cm.sup.3/g,
preferably greater than 0.9 cm.sup.3/g, crystallite sizes (measured
on the 020 reflex) of greater than 10 nm, preferably greater than
12 nm, and surfaces of greater than 150 m.sup.2, preferably 150 to
200 m.sup.2. In contrast thereto, it is preferred that the
crystalline boehmitic aluminas of the present invention prepared
according to the third embodiment, independently of one another,
have the following characteristics: pore volumes of greater than
0.7 cm.sup.3/g, preferably greater than 0.9 cm.sup.3/g, crystallite
sizes (measured on the 020 reflex) from about 6 to 10 nm, and
surfaces of greater than 200 m.sup.2.
[0019] The aluminium oxides prepared from the crystalline aluminas
of the present invention by thermal treatment at higher than
150.degree. C., preferably by calcination at temperatures from 800
to 1,500.degree. C. for at least 0.5 hour are a further object of
the present invention. Said aluminium oxides are distinguished by
their particularly large surfaces, large pore volumes, and
excellent high-temperature stabilities. The term `thermal
stability` employed herein means stability to changes in the
surface or crystalline phase brought about by external influences,
such as water, chemicals, pressure, or mechanical stress and
temperature.
[0020] Furthermore, the aluminium oxide hydrates and aluminium
oxides according to the present invention are pure-phase and
stable-phase products which are present as delta, theta, or alpha
modifications, depending on the calcination time and temperature.
More details are presented in the tables 1, 2, and 3 showing the
powder diffraction pattern data of the different aluminium oxides
of this invention.
[0021] The term `pure-phase` employed herein means that more than
90 wt. %, preferably more than 98 wt. % of the crystalline
aluminium oxide consists of a single phase (determined by X-ray
powder diffraction). The theta-aluminium oxides of the present
invention are pure-phase products on the condition that
particularly the d-values (as {dot over (A)}) do not present any
peaks in the X-ray powder diffraction pattern which are
characteristic of .alpha.-Al.sub.2O.sub.3.
[0022] With respect to the X-ray powder diffraction patterns of
conventional aluminium oxides, reference is made to the
corresponding JCPDS sheets (US National Bureau of Standards) for
corundum (.alpha.-Al.sub.2O.sub.3), delta- and theta-aluminium
oxide.
[0023] The term `stable-phase` employed herein means that the
crystalline phase will not change even if the product is exposed
for a long time to the same or lower temperature used in the
production of said aluminium oxide by calcination.
[0024] Furthermore, the aluminium oxides of the present invention
are temperature-stable and, contrary to conventional aluminium
oxides, have surfaces of larger than 60 m.sup.2/, preferably larger
than 70 m.sup.2/g, even after calcination at 1,200.degree. C. for 3
hours. The calcination is performed in heated air in a muffle
furnace.
[0025] The aluminium oxides of the present invention have pore
volumes of greater than 0.6 cm.sup.3/g, preferably from 0.7 to 1
cm.sup.3/g (determined by the mercury penetration method in
accordance with DIN 66 133) within a pore radius range from 1.8 to
100 nm. The aluminium oxides of this invention keep said
characteristic even after exposure to temperatures of 1,100.degree.
C. for 24 hours. Conventional aluminium oxides, e.g. those obtained
by calcination of bayerite, present distinctly smaller pore volumes
(about 0.2 to 0.4 cm.sup.3/g).
[0026] The aluminium oxides of this invention are most useful as
catalysts or catalyst supports, particularly as support material
for automobile exhaust gas catalysts. In this case the catalyst
support is treated with noble metal catalysts, such as platinum or
palladium.
[0027] When using the aluminium oxides of this invention, the
catalyst or catalyst support can be applied in thin layers which
remain stable even at high temperatures, e.g. of greater than
1,000.degree. C. This characteristic is most advantageous in
exhaust gas catalyst applications. Furthermore, stabilization aids,
such as lanthane oxide or SiO.sub.2, employed in technical
applications can mostly be dispensed with. Stabilization aids made
of metal oxides may have adverse effects on the catalytic behavior
of the Al.sub.2O.sub.3 catalyst or catalyst support.
[0028] The crystallite sizes of the boehmitic aluminas according to
this invention were determined on the 120 and 020 reflexes using
the general Scherrer formula:
Crystallite size=(K.times.lambda.times.57.3)/(beta.times.cos
theta)
1 K (form factor): 0.992 Lambda (X-ray wave length): 0.154 nm Beta
(corrected line broadening of apparatus): reflex- dependent Theta:
reflex- dependent
[0029] The measurements were carried out using a Philips XRD X'pert
apparatus. The measurement parameters for the samples obtained in
Example 1 (Comparative Example) and Example 2 have been compiled in
Tables 1 and 2, respectively.
[0030] The reflexes 120 and 020 (Miller indices) were determined on
the boehmite and relate to the unconventional crystallographic Amam
mounting of orthorhombic space group no. 63. The conventional
mounting is Cmcn, wherein the a- and c-axes have been exchanged in
comparison with the unconventional Amam mounting.
[0031] The surface areas of the aluminium oxides of this invention
were determined by the N.sub.2 sorption method (BET method in
accordance with DIN 66131). The pore volumes and pore volume
distributions were determined by the mercury intrusion
(penetration) method in accordance with DIN 66133 using a mercury
porosimeter. The pore volumes were reported as cumulative volumes
in cm.sup.3/g in accordance with DIN 66133.
EXAMPLE 1
Comparative Example
[0032] First, an alumina slurry to be employed as the starting
material was prepared by neutral aluminium alcoholate
hydrolysis:
[0033] An aluminium alcoholate mixture obtained as an intermediate
in the Ziegler/Alfol process was hydrolyzed with water which had
been liberated from foreign ions in a demineralization unit. The
hydrolysis was performed at 90.degree. C. in an agitated kettle.
The resultant two phases, i.e. the upper alcohol phase and the
lower alumina/water phase, were immiscible.
[0034] 500 grams of this alumina slurry (pH 9) containing 10 to 11
wt. % Al.sub.2O.sub.3 were added in portions to a reactor operated
at a pressure of 3 bar corresponding to 115.degree. C. After the
reaction conditions had been adjusted, the slurry was allowed to
age for 4 hours using a standard agitator running at a peripheral
velocity of 1.6 m/s corresponding to an agitator speed of 500
r.p.m.
[0035] The following values were obtained:
2 Reflex Beta Theta Crystallite Size 120 0.919 14.degree. 9.8 nm
020 0.919 7.degree. 6.7 nm
[0036] The 120 reflex is greater by 3.1 nm than the 020 reflex.
[0037] The specific surface was determined by the N.sub.2 sorption
method (BET method). After thermal treatment at 1,200.degree. C.
for 3 hours the specific surface was found to be 46 m.sup.2/g. The
X-ray powder diffraction pattern of said sample is shown in Table
1. It presents significant alpha-phase signals.
EXAMPLE 2
[0038] 500 grams of the alumina slurry (pH 9) containing 10 to 11
wt. % Al.sub.2O.sub.3 as defined in the Comparative Example were
added in portions to a reactor operated at normal pressure and
98.degree. C. After the reaction conditions had been adjusted, the
slurry was allowed to age for 16 hours using a standard agitator
running at a peripheral velocity of 1.6 m/s corresponding to an
agitator speed of 500 r.p.m. The crystallite sizes measured as
described in the Comparative Example were 13.5 nm (120 reflex) and
12.1 nm (020 reflex).
[0039] After thermal treatment at 1,200.degree. C. for 3 hours the
specific surface was found to be 68 m.sup.2/g. The X-ray powder
diffraction pattern of this sample is shown in Table 1. It presents
theta-phase signals. The aluminium oxide is present in the theta
phase with a phase purity of greater than 98%.
[0040] After aging for 20 hours under the conditions specified
hereinabove the crystallite sizes were found to be 13.5 nm (120
reflex) and 13.0 nm (020 reflex).
EXAMPLE 3
[0041] 500 grams of the alumina slurry (pH 9) containing 10 to 11
wt. % Al.sub.2O.sub.3 as defined in the Comparative Example were
added in portions to a reactor operated at a pressure of 3 bar
corresponding to 110.degree. C. After the reaction conditions had
been adjusted, the slurry was allowed to age for 40 hours using a
standard agitator running at a peripheral velocity of 1.6 m/s
corresponding to an agitator speed of 500 r.p.m.
[0042] The crystallite sizes measured as described in the
Comparative Example were 15.3 nm (120 reflex) and 15.3 nm (020
reflex). After thermal treatment at 1,200.degree. C. for 3 hours
the specific surface was found to be 67 m.sup.2/g.
EXAMPLE 4
[0043] 500 grams of the alumina slurry (pH 9) containing 10 to 11
wt. % Al.sub.2O.sub.3 as defined in the Comparative Example were
added in portions to a reactor operated at a pressure of 3 bar
corresponding to 110.degree. C. After the reaction conditions had
been adjusted, the slurry was allowed to age for 60 hours using a
standard agitator running at a peripheral velocity of 1.6 m/s
corresponding to an agitator speed of 500 r.p.m.
[0044] The crystallite sizes measured as described in the
Comparative Example were 16.1 nm (120 reflex) and 16.5 nm (020
reflex). After thermal treatment at 1,200.degree. C. for 3 hours
the specific surface was found to be 72 m.sup.2/g.
EXAMPLE 5
[0045] 600 grams of the alumina slurry (pH 9) containing 10 to 11
wt. % Al.sub.2O.sub.3 as defined in the Comparative Example were
added to 50 grams of a 20% aqueous tetrene solution and boiled
under reflux for 68 hours. 300 grams of H.sub.2O were added to this
mixture at one-hour intervals. The mixture was diluted with 200
grams of H.sub.2O und spray dried.
[0046] The crystallite sizes measured as described in the
Comparative Example were 14.4 nm (120 reflex) and 14.6 nm (020
reflex). After thermal treatment at 1,200.degree. C. for 3 hours
the specific surface was found to be 81 m.sup.2/g.
EXAMPLE 6
[0047] 300 grams of a 6.02% aluminium-tri-n-hexanolate solution in
n-hexanol were added at 90.degree. C. to 360 grams of a 5% aqueous
tetrene solution. This mixture was agitated at 90.degree. C. for 30
minutes. The hexanol was removed from the reaction mixture by
azeotropic distillation. The residue then was agitated at
90.degree. C. for 24 hours. H.sub.2O was added in 100-gram portions
after 1 hour, 2 hours, and 3 hours, respectively. The reaction
mixture was spray dried.
[0048] The crystallite sizes measured as described in the
Comparative Example were 11.0 nm (120 reflex) and 11.8 nm (020
reflex). After thermal treatment at 1,200.degree. C. for 3 hours
the specific surface was found to be 76 m.sup.2/g.
EXAMPLE 7
[0049] 300 grams of a 6.02% aluminium-tri-n-hexanolate solution in
n-hexanol were added at 90.degree. C. to 360 grams of a 5% aqueous
tetrene solution. This mixture was agitated at 90.degree. C. for 30
minutes. The hexanol was removed from the reaction mixture by
azeotropic distillation. The residue then was agitated at
90.degree. C. for 68 hours. H.sub.2O was added in 100-gram portions
after 1 hour, 2 hours, and 3 hours, respectively. The reaction
mixture was spray dried.
[0050] The crystallite sizes measured as described in the
Comparative Example were 12.6 nm (120 reflex) and 16.4 nm (020
reflex). After thermal treatment at 1,200.degree. C. for 3 hours
the specific surface was found to be 79 m.sup.2/g.
3TABLE 1 X-Ray Powder Diffraction Pattern of Example 1 (Comparative
Example) with Significant Quantity of Alpha-Al.sub.2O.sub.3 d-Value
d-Value T-Width Height Backgr. Rel. Int. d-Value [.degree.2.theta.]
.alpha..sup.1 [.ANG.] .alpha..sup.2 [.ANG.] [.degree.2.theta.]
[counts] [counts] [%] Signific. 16.205 5.46527 5.47872 0.480 19 29
4.1 1.56 19.550 4.53706 4.54822 0.480 45 27 9.5 2.53 21.850 4.06440
4.07439 0.480 9 24 1.9 0.80 25.560 3.48224 3.49081 0.180 276 30
58.5 7.44 31.230 2.86174 2.86878 0.200 286 41 60.7 2.47 32.695
2.73678 2.74351 0.120 441 37 93.7 1.23 32.825 2.72624 2.73294 0.080
441 37 93.7 0.97 35.135 2.55211 2.55838 0.140 449 35 95.4 4.34
36.660 2.44937 2.45539 0.200 313 34 66.5 1.41 37.695 2.38446
2.39032 0.140 185 31 39.3 2.48 38.910 2.31275 2.31844 0.120 266 30
56.4 0.91 39.855 2.26007 2.26563 0.160 169 30 35.9 0.92 41.715
2.16349 2.16881 0.480 21 27 4.5 1.69 43.305 2.08767 2.09280 0.160
396 27 84.1 6.77 44.785 2.02205 2.02703 0.320 282 26 59.9 9.47
45.605 1.98758 1.99247 0.360 137 25 29.1 3.48 46.515 1.95080
1.95560 0.240 90 24 19.2 2.18 47.630 1.90770 1.91239 0.120 185 23
39.3 1.31 50.680 1.79981 1.80424 0.320 77 22 16.4 4.82 51.520
1.77242 1.77678 0.320 22 22 4.7 0.78 52.450 1.74317 1.74745 0.100
154 22 32.7 1.18 57.415 1.60366 1.60761 0.160 317 25 67.3 6.46
58.730 1.57085 1.57471 0.240 26 25 5.5 0.76 59.820 1.54480 1.54861
0.120 114 25 24.3 1.93 61.240 1.51234 1.51606 0.160 74 25 15.7 1.05
62.295 1.48924 1.49291 0.400 71 24 15.0 2.02 63.850 1.45667 1.46025
0.240 137 24 29.1 3.28 64.165 1.45028 1.45385 0.120 98 24 20.8 1.06
65.450 1.42488 1.42838 0.320 59 23 12.6 1.06 66.475 1.40537 1.40883
0.100 324 24 68.8 0.85 67.395 1.38841 1.39182 0.440 471 23 100.0
18.43 68.155 1.37477 1.37815 0.100 190 23 40.4 0.92 72.900 1.29654
1.29973 0.320 41 21 8.7 1.33 73.700 1.28443 1.28759 0.400 48 21
10.1 2.55 75.460 1.25878 1.26188 0.560 28 19 6.0 4.30 76.800
1.24012 1.24317 0.160 58 18 12.3 1.06 Measurement parameters: Start
angle [.degree.2.theta.]: 5.010; end angle [.degree.2.theta.]:
79.990; start d-value [.ANG.]: 17.62435; end d-value [.ANG.]:
1.19850; anode material: Cu; .alpha..sup.1 wave length [.ANG.]:
1.54060; .alpha..sup.2 wave length [.ANG.]: 1.54439
[0051]
4TABLE 2 X-Ray Powder Diffraction Pattern of Example 2
(Al.sub.2O.sub.3 with > 98% Theta Phase) d-Value d-Value T-Width
Height Backgr. Rel. Int. d-Value [.degree.2.theta.] .alpha..sup.1
[.ANG.] .alpha..sup.2 [.ANG.] [.degree.2.theta.] [counts] [counts]
[%] Signific. 16.240 5.45357 5.46699 0.400 40 28 6.6 1.55 19.495
4.54974 4.56093 0.400 56 30 9.4 1.21 25.230 3.52704 3.53571 0.800
11 28 1.8 1.26 31.130 2.87070 2.87777 0.320 292 42 48.7 4.94 32.685
2.73759 2.74433 0.180 600 42 100.0 3.57 32.790 2.72907 2.73578
0.060 562 42 93.6 0.80 34.845 2.57268 2.57901 0.320 102 41 17.0
2.05 36.635 2.45098 2.45701 0.320 372 40 62.1 5.21 38.820 2.31791
2.32361 0.280 266 41 44.3 4.26 39.890 2.25816 2.26372 0.240 196 40
32.7 1.80 43.295 2.08813 2.09326 0.320 15 29 2.5 1.01 44.720
2.02484 2.02982 0.360 361 28 60.1 12.86 46.530 1.95020 1.95500
0.480 59 27 9.9 0.93 47.585 1.90940 1.91410 0.280 196 25 32.7 5.21
50.585 1.80297 1.80741 0.240 85 24 14.1 2.69 51.470 1.77403 1.77839
0.320 31 23 5.2 1.18 52.455 1.74301 1.74730 0.320 22 23 3.7 1.03
56.580 1.62533 1.62933 0.640 18 23 2.9 0.99 57.365 1.60494 1.60889
0.320 20 24 3.4 0.75 58.755 1.57024 1.57410 0.240 37 24 6.2 2.28
59.850 1.54410 1.54790 0.200 139 24 23.2 1.67 62.310 1.48892
1.49258 0.400 100 24 16.7 2.83 63.925 1.45514 1.45872 0.400 164 25
27.3 10.08 65.355 1.42672 1.43023 0.480 69 26 11.5 2.58 66.450
1.40584 1.40930 0.240 228 25 38.0 2.47 67.395 1.38841 1.39182 0.600
524 26 87.4 39.85 72.845 1.29738 1.30057 0.480 50 24 8.4 2.92
73.715 1.28420 1.28736 0.400 64 23 10.7 3.36 75.295 1.26113 1.26423
0.400 27 20 4.5 1.56 77.320 1.23308 1.23611 0.960 15 18 2.5
3.48
[0052] Measurement parameters as specified in Table 1.
5TABLE 3 X-Ray Powder Diffraction Pattern of an Aluminium Oxide of
this Invention in the Delta Phase d-Value d-Value T-Width Height
Backgr. Rel. Int. d-Value [.degree.2.theta.] .alpha..sup.1 [.ANG.]
.alpha..sup.2 [.ANG.] [.degree.2.theta.] [counts] [counts] [%]
Signific. 19.605 4.52446 4.53559 0.480 21 49 6.2 0.82 32.855
2.72382 2.73052 0.560 69 139 20.3 2.95 36.865 2.43621 2.44221 0.320
114 132 33.8 0.95 39.570 2.27568 2.28128 0.880 117 90 34.5 10.25
45.475 1.99296 1.99787 0.560 272 58 80.4 7.14 46.385 1.95596
1.96077 0.480 146 56 43.2 2.24 50.865 1.79370 1.79811 0.800 10 40
3.0 1.35 58.990 1.56455 1.56839 0.140 11 61 3.2 0.85 59.985 1.54095
1.54474 0.800 18 74 5.5 1.38 66.470 1.40547 1.40892 0.560 279 83
82.4 3.34 67.220 1.39160 1.39502 0.240 339 76 100.0 0.99
[0053] Measurement parameters as specified in Table 1.
* * * * *