Zirconia-pillared clays and micas

The present invention is directed to improved zirconia-pillared clays exhibiting high crystallinity and layer spacing and significantly higher thermal stability prepared using zirconyl acetate as the pillaring agent by: (a) mixing a clay selected from the group consisting of smectite clays and fluoromicas with a solution of zirconyl acetate for a time and at a temperature sufficient to form a pillared clay product; (b) separating said pillared clay product formed from the solution; (c) washing the separated pillared clay product with water; (d) drying the separated, washed pillared clay product at a temperature from about 50.degree. to 200.degree. C.; (e) calcining the dried pillared clay product at a temperature from about 300.degree. to 700.degree. C.

FIELD OF THE INVENTION 
Applicants have found an improved method of preparing zirconia-pillared 
clays, especially zirconia-pillared fluoromicas. The method is more 
convenient and reproducible, affording pillared clays with consistently 
higher crystallinity and layer spacing, and significantly higher thermal 
stability as compared with zirconia-pillared clays prepared in accordance 
with the prior art. 
The zirconia-pillared clays prepared in accordance with the present 
invention, resist collapse when exposed to high temperatures and further 
maintain a significant surface area when subjected to steam contact. 
Furthermore, the pillaring solution of the present invention need not be 
heated, thereby allowing the pillaring reaction to be carried out at 
ambient temperatures. 
SUMMARY OF THE INVENTION 
The present invention is directed to improved zirconia-pillared clays and a 
method of producing the same. The method comprises the steps of 
(a) mixing a clay selected from the group consisting of smectite clays and 
fluoromicas with a solution of zirconyl acetate for a time and at a 
temperature sufficient to form a pillared clay product; 
(b) separating said pillared clay product formed from the solution; 
(c) washing the separated pillared clay product with water; 
(d) drying the separated, washed pillared clay product at a temperature 
from about 50.degree. to 200.degree. C.; 
(e) calcining the dried pillared clay product at a temperature from about 
300.degree. to 700.degree. C. 
In a further embodiment the process additionally includes step (f) washing 
the pillared clay product following said calcination step (e) when said 
clay is a fluoromica. 
The invention is further directed to an improved zirconia-pillared clay 
made in accordance with the process described in steps (a), (b), (c), (d), 
and (e), more preferably, when the clay is a fluoromica, the process will 
also include step (f). 
The invention is further directed to the use of the present invention 
zirconia-pillared clay in hydrocarbon conversion reactions such as 
catalytic cracking. 
The clays used in the present invention may be any smectite clay or 
fluoromica, however, the fluoromicas are preferred.

DETAILED DESCRIPTION OF THE INVENTION 
The catalysts of the present invention are prepared from naturally 
occurring and synthetic smectites, such as montmorillonite, beidellite, 
nontronite, saponite, hectorite, and fluorohectorite, and from synthetic 
fluoromicas such as sodium tetrasilicic mica (NaTSM) and synthetic 
taeniolite. Smectites and micas are formed of sheets that may be 
visualized as a sandwich comprising two outer sheets of silicon tetrahedra 
and an inner layer of aluminum octahedra (i.e. 2:1 layered clay). These 
clays are generally represented by the general formula: 
EQU A.sub.x [M.sub.2-3 T.sub.4 O.sub.10 (Y).sub.2] 
where M designates the octahedral cation, T designates the tetrahedral 
cation, A designates the exchangeable interlayer cations, 
0.ltoreq.X.ltoreq.1, and Y is hydroxy (OH) or fluorine (F) either singly 
or in combination. The T coordinated ion is commonly Si.sup.+4, Al.sup.30 
3, or Fe.sup.+3, but could also include several other four-coordinate 
ions, e.g., p.sup.+5, B.sup.+3, Ga.sup.+3, Cr.sup.+3, Ge.sup.+4, 
Be.sup.+2, etc. The M coordinated ion is typically Al.sup.+3 or Mg.sup.+2, 
but could also include many other possible hexacoordinate ions, e.g., 
Fe.sup.+3, Fe.sup.+2, Ni.sup.+2, Co.sup.+2, Li.sup.+, Cr.sup.+3, V.sup.+2, 
etc. Mg.sup.+2 is preferred in this invention. 
Synthetic fluoromicas such as sodium tetrasilicic fluoromica (Na[Mg.sub.2.5 
Si.sub.4 O.sub.10 F.sub.2 ]and lithium taeniolite (Li[(Mg.sub.2 
Li)Si.sub.4 O.sub.10 F.sub.2 ]) undergo swelling in water and other 
suitable polar solvents. Even though fluoromicas such as these exhibit 
high layer charge densities, they are capable of undergoing pillaring 
reactions with large cations. The resulting pillared tetrasilicic micas 
exhibit good thermal stability and are good catalytic cracking, 
isomerization, etc., catalysts. 
The inorganic polymer, or pillaring agent, used to prepare the pillared 
clays of the present invention is zirconyl acetate, having a nominal 
formula of ZrO(OH).sub.0.5 (CH.sub.3 COO).sub.1.5, which is commercially 
available. 
The clay selected is contacted with an aqueous zirconyl acetate solution, 
which has been diluted with water or another suitable polar solvent, and 
allowed to react for a time and at a temperature sufficient to form a 
solid pillared clay material. This contacting is also referred to as 
pillaring. Preferably the reaction will be carried out for about 0.2 to 
about 24 hours, more preferably, 1 to about 6 hours. The temperature 
during pillaring ranges between 0.degree. to 50.degree. C., preferably 
15.degree. to 35.degree. C. Most preferably the reaction is carried out at 
room temperature. The amounts of zirconyl acetate solution and clay are 
chosen such that a desired ratio of Zr/clay will be obtained. The Zr/clay 
ratio will be at least about 4 mmole Zr per g of clay, preferably about 4 
to about 46 mmole Zr per g of clay, most preferably about 23 mmoles Zr per 
g of clay. The resulting solid clay material obtained after contacting may 
then be separated from solution by filtration or centrifugation followed 
by washing with distilled water. The washing is continued until the acetic 
acid odor is not noticeable. The number of washes varies depending on the 
size of the sample and efficiency of wash. The number of washes is readily 
determinable by one skilled in the art. Generally about 4-8 washes will be 
sufficient. The material is then dried between about 50.degree. and 
200.degree. C. The material is then calcined at a temperature of about 
300.degree. C. to 700.degree. C., for about 1 to 24 hours, preferably the 
material will be held at a temperature at or above about 400.degree. C. 
for about 1 to 24 hours. Calcination decomposes the zirconium hydroxy 
acetate complex and forms pillars of zirconium oxide. The resulting 
pillared clays may additionally be washed, for example, with water to 
remove labilized sodium, formed when utilizing NaTSM, and to obtain 
enhanced thermal stability. 
The clays obtained from the present invention are microporous materials 
having two dimensional galleries with 10-12 angstrom height. The surface 
areas are about 300-400 m.sup.2 /g and are stable to high temperatures, at 
or above 700.degree. C. Micropore volumes calculated from the nitrogen 
isotherm using the t-plot method are 0.10 to 0.12 mL/g. The layer repeat 
distances are 20-22 angstroms as measured by X-ray diffraction. The 
zirconia-pillared clays of the present invention exhibit a high degree of 
order in the interlayer spacing following calcination. After steaming in 
100% steam at 760.degree. C. for 17 hours, the surface area in some cases 
is reduced only to about 200 m.sup.2 /g. Hence, the zirconia-pillared 
clays of the present invention are capable of acting as catalysts after 
regeneration in the presence of steam. 
EXAMPLE 1 
A series of experiments was carried out to ascertain the affect of the 
ratio of zirconium to TSM in the pillaring step. All reactions were 
carried out at room temperature for three hours. A series of eight samples 
was prepared in which the Zr/TSM ratio was 2.3, 4.6, 9.2, 13.8, 18.4, 23, 
34.5, and 46 mmole Zr/g TSM. The amount of zirconyl acetate solution 
(ZAA), required to obtain the desired Zr/TSM ratio was added to 100 mL of 
distilled water and stirred at room temperature for 10 minutes. One gram 
of NaTSM was added and the resulting milky white dispersion was stirred 
for three hours at room temperature and then separated by centrifugation. 
The solid product was then washed by redispersion in 1 L of distilled 
water followed by separation by centrifugation. The washing procedure was 
repeated until the acetic acid odor was greatly reduced in the decantates 
(8 washes). The first wash produced a great deal of foam which required 
about 30 minutes to settle. The foaming disappeared after the second wash. 
The samples were then filtered and dried at 120.degree. C. overnight. 
X-ray diffraction at this point in the reaction indicated that there was 
not a high degree of order in the interlayer spacing. Two broad weak peaks 
at about 20 and 10 angstroms were present on a high background in the low 
angle region of the diffraction patterns. The samples were then calcined 
in air at 200.degree. C. for two hours, heated to 400.degree. C. at 
50.degree. C./hr, and held at 400.degree. C. for two hours. When the 
samples were calcined at 400.degree. C., the resulting diffraction 
patterns had a significantly sharper and stronger peak at 20.1 to 20.6 
angstroms depending on the Zr/TSM ratio. See FIG. 1A. The results indicate 
that an excess of zirconyl acetate in the pillaring step is beneficial in 
enhancing the crystallinity of the zirconia-pillared micas. When only 2.3 
mmole Zr/g TSM was used, no diffraction maxima corresponding to an 
expanded interlayer spacing was observed. As the amount of zirconyl 
acetate is increased, a peak in the X-ray diffraction pattern appears at 
slightly greater than 20 angstroms and is maximized at a ratio of 23 mmole 
Zr/g TSM. The peak appears at all ratios from 9.3 to 46 mmole Zr/g TSM. 
The results are presented in Table I. 
TABLE I 
__________________________________________________________________________ 
ml ZrOAc/g TSM 
1 2 4 6 8 10 15 20 
mmole Zr/g TSM 
2.3 4.6 9.3 13.9 
18.6 
23.2 
34.8 
46.4 
g ZrO2/g TSM 
0.3 0.6 1.1 1.7 2.3 2.9 4.3 5.7 
surface area(m.sup.2 /g) 
184 308 319 301 294 290 313 311 
mircopore volume 
0.057 
0.102 
0.111 
0.105 
0.110 
0.107 
0.117 
0.109 
(mL/g) 
% Zr 16.24 
21.32 
19.28 
19.62 
18.20 
17.88 
17.66 
17.72 
% Si 20.54 
16.82 
18.70 
20.42 
19.12 
20.06 
19.96 
22.14 
% Mg 8.63 
7.13 
8.64 
7.88 
7.86 
7.48 
8.17 
8.25 
% Na 1.14 
0.99 
1.18 
1.01 
1.14 
1.00 
1.19 
1.03 
__________________________________________________________________________ 
The analytical results indicate that at least three-fourths of the sodium 
in the interlayer space of the NaTSM is exchanged by the polyoxocations. 
Furthermore, the results show a maximum in zirconium content in the sample 
prepared with 4.6 mmole Zr/g TSM and a slight decrease in the amount of 
zirconium incorporated as the amount of zirconyl acetate used in pillaring 
increases. 
The surface areas of the zirconia-pillared micas in this series are not as 
sensitive to the Zr/TSM ratio as are the X-ray crystallinities. As shown 
in Table I, the surface area of the sample prepared with the lowest amount 
of zirconyl acetate is only 184 m.sup.2 /g, but the rest of the samples 
have surface areas between 290-319 m.sup.2 /g. The shape of nitrogen 
uptake isotherms approaches ideal type 1 behavior as the crystallinity of 
the samples increases. FIG. 2 shows the isotherms for three representative 
samples prepared at Zr/TSM ratios of 2.3, 4.6, and 35 mmole Zr/g TSM. The 
isotherms for the samples prepared with ratios from 9 to 46 mmole Zr/g TSM 
were of a shape similar to that of the 35 mmole Zr/g TSM sample shown in 
the figure. Type 1 isotherms indicate the presence of micropores (R.sub.p 
&lt;20 .ANG.) and are characteristic of zeolites and well-ordered pillared 
clays. 
EXAMPLE 2 
The amount of ZAA required to obtain Zr/TSM ratios of 11.6, 23.2, and 34.8 
mmole Zr/g TSM was added to 750 mL of distilled water and stirred at room 
temperature for ten minutes. 10 g of NaTSM was added and the resulting 
milky white dispersion was stirred for three hours at room temperature. 
The products were isolated and calcined as described in Example 1. Half of 
each of the products was then stirred with 700 mL of distilled water at 
room temperature for 3 hours and then separated by centrifugation. This 
procedure was repeated three times over a twenty four hour period. The 
samples were filtered and dried at 120.degree. C. overnight. The samples 
were then calcined in air at 250.degree. C. for two hours then heated to 
400.degree. C. for two hours. The results are presented in Table II. 
TABLE II 
__________________________________________________________________________ 
Calcined 
Washed 
Calcined 
Washed 
Calcined 
Washed 
__________________________________________________________________________ 
ml ZrOAc/g TSM 
5 5 10 10 15 15 
mmole Zr/g TSM 
11.6 11.6 23.2 23.2 34.8 34.8 
g ZrO2/g TSM 
1.4 1.4 2.9 2.9 4.3 4.3 
surface area 
308 332 328 339 311 339 
micropore volume 
0.109 
0.120 
0.113 
0.118 
0.104 
0.119 
% Zr 23.20 
24.00 
21.75 
22.15 
21.60 
22.22 
% Si 19.35 
20.10 
20.35 
20.30 
20.45 
20.75 
% Mg 8.69 9.40 8.89 9.13 9.08 9.53 
% Na 0.77 0.15 0.61 0.25 0.75 0.20 
__________________________________________________________________________ 
Calcination labilizes some of the sodium ions that are not exchanged by the 
zirconia pillaring cations and they can then be removed by a post 
calcination wash. The results show that the washed samples exhibit 
slightly higher surface area and micropore volumes than the unwashed 
samples of Example 1. The sample prepared with 12 mmole Zr/g TSM had a 
slightly higher zirconium content than the two samples prepared at higher 
Zr/TSM ratios, confirming the trend shown in the Example 1 samples. 
However, little variation was detected by X-ray diffraction, and nitrogen 
adsorption data show that the surface area and micropore volume are 
highest in the sample prepared with 23 mmole Zr/g TSM. 
EXAMPLE 3 
A series of steaming experiments was conducted at temperatures of 
650.degree., 700.degree., and 760.degree. C. Fresh 0.5 g samples of ZrTSM 
prepared with Zr/TSM ratios of 11.6, 23.2, and 34.8 mmole Zr/g were used. 
Two samples at each Zr/TSM ratio were prepared, one that had been washed 
after calcining as in Example 2, while the other was unwashed. 
The ZrTSM samples were spread in a shallow layer inside quartz tubes and 
inserted into a steaming apparatus designed for deactivating cracking 
catalysts. The samples were exposed to pure steam flowing at approximately 
1200 to 1400 cm.sup.3 /min for 17 hours at controlled temperature. 
TABLE III 
__________________________________________________________________________ 
Surface Area (m.sup.2 /g) of ZrTSM 
After Steaming 17 Hours in 100% Steam 
mmole Zr/g TSM 
Unsteamed 
650.degree. C. Steam 
700.degree. C. Steam 
760.degree. C. Steam 
__________________________________________________________________________ 
11.6, unwashed 
308 217 173 95 
11.6, washed 
332 254 218 172 
23.2, unwashed 
328 283 241 20 
23.2, washed 
339 306 260 194 
34.8, unwashed 
311 278 234 20 
34.8, washed 
339 298 258 184 
__________________________________________________________________________ 
The results of surface area measurement, presented in Table III, of the 
steamed samples indicate that as steaming temperature is increased, the 
difference in surface area between washed and unwashed samples becomes 
more pronounced. After steaming at 760.degree. C. the washed sample having 
23 mmole Zr/g TSM exhibited the highest surface area of 194 m.sup.2 /g, 
only a 43% loss from its original surface area of 339 m.sup.2 /g before 
steaming. In contrast, the same sample, without washing, when steamed at 
760.degree. C. lost 94% of its surface area, retaining only 20 m.sup.2 /g. 
The deleterious effects of small amounts of sodium on the hydrothermal 
stability of zirconia-pillared tetrasilicic mica becomes more important as 
the temperature of the steam treatment increases. 
EXAMPLE 4 
A series of X-ray powder diffraction patterns of zirconia-pillared 
tetrasilicic mica samples prepared with 23 mmole Zr/g TSM, and steamed at 
650.degree., 700.degree., and 760.degree. C. were compared for both 
unwashed and washed samples prepared in accordance with the procedures 
outlined in Examples 1 and 2. (See FIGS. 1B and 1C respectively.) The 
enhancement of hydrothermal stability obtained by the removal of sodium by 
the post calcination wash was evident. The washed sample of 
zirconia-pillared tetrasilicic mica after 760.degree. C. steaming had a 
surface area of 194 m.sup.2 /g and a micropore volume of 0.073 mL/g, 
though the layer spacing line is no longer detectable in the X-ray powder 
diffraction pattern. The X-ray diffraction patterns exhibited broad new 
lines at 2 theta=30.degree., 35.degree., 50.degree., and 60.degree. which 
grew with increasing temperature of steam treatment. The lines were in the 
position expected for the tetragonal phase of zirconium dioxide. There was 
no significant difference in the line widths of the ZrO.sub.2 lines for 
the washed and unwashed samples before or after steaming at 650.degree. 
and 700.degree. C., but after-steaming at 760.degree. C. the ZrO.sub.2 
lines in the diffraction pattern of the unwashed sample were sharper (see 
Table IV), demonstrating that sodium enhances the growth of ZrO.sub.2 
microcrystallites during steam treatment. 
TABLE IV 
__________________________________________________________________________ 
fhwm(.degree.) 
d(.ANG.) fhwm(.degree.) 
d(.ANG.) 
__________________________________________________________________________ 
unwashed 
400.degree. C. 
4.92 17 washed 
400.degree. C. 
5.1 16 
calcined calcined 
650.degree. C. 
3.08 27 650.degree. C. 
3.3 25 
steamed steamed 
700.degree. C. 
2.62 31 700.degree. C. 
2.72 30 
steamed steamed 
760.degree. C. 
1.83 45 760.degree. C. 
2.23 37 
steamed steamed 
__________________________________________________________________________ 
Line widths (fwhm) and crystallite diameters (d) calculated from the 
Scherrer equation, d = 0.9.lambda./(fwhm .multidot. cos.theta.), for 
zirconiapillared tetrasilicic mica prepared with 23 mmole Zr/g TSM, using 
the 101 line of tetragonal ZrO.sub.2 at 2.theta. = 29.1.degree.. 
EXAMPLE 5 
(comparative) 
A sample of zirconia-pillared was mica prepared by treating a dilute 
aqueous suspension of size-fractionated NaTSM with an aqueous solution of 
zirconyl chloride, the pillaring agent commonly employed by the prior art, 
followed by washing and calcination at 400.degree. C. to form zirconia 
pillared TSM. The sample was prepared using a solution of 
ZrOCl.sub.2.4H.sub.2 O that had been refluxed for 24 hours prior to 
pillaring at room temperature. The layer spacing of the sample was 21 
angstroms, however the sample did not show a high degree of order as 
demonstrated by its X-ray powder diffraction pattern. The peak 
representing the layer spacing was only a shoulder on the low angle 
background unlike the sharp peak observed for NaTSM pillared with zirconyl 
acetate in accordance with the present invention. The sample exhibited a 
surface area of only 231 m.sup.2 /g. Additionally, reproducible results 
were not obtainable. In preparing a large batch of ZrTSM pillared by 
zirconyl chloride, the 21 angstrom shoulder observed previously in the 
X-ray powder diffraction pattern was absent after calcination of the 
product at 400.degree. C. and the surface area was only 108 m.sup.2 /g. 
After steaming for 17 hours in 100% steam at 700.degree. C., the surface 
area of the zirconyl chloride pillared TSM fell to 48 m.sup.2 /g, and to 
31 m.sup.2 /g after 760.degree. C. calcination. The results demonstrate 
both the superior reproducibility of the zirconyl acetate preparation and 
the higher crystallinity and stability of the pillared micas produced from 
it. 
EXAMPLE 6 
Zirconia-pillared clay using montmorillonite 
A commercially available montmorillonite (bentonite HPM-20 from American 
Colloid Company) was pillared with zirconia following a procedure similar 
to that of Example 1. ZAA solution (100 mL, 232 mmole Zr) was diluted with 
750 mL distilled water. 10.0 g montmorillonite was added and the resulting 
suspension was stirred at ambient temperature for 3 hours. The solid was 
separated by filtration and dried at 120.degree. C. The sample was then 
calcined in a muffle furnace at 200.degree. C. for two hours, heated to 
400.degree. C. at 50.degree. C./hour, and held at 400.degree. C. for 2 
hours. The layer spacing measured by X-ray diffraction was 20.2 .ANG. and 
the surface area was 388 m.sup.2 /g. Steaming tests were carried out on 
this sample of Zr-montmorillonite as described in Example 3. After steam 
treatment at 650.degree. C. for 17 hours, the surface area is 228 m.sup.2 
/g; after steam treatment at 700.degree. C. for 17 hours, the surface 
area is 86 m.sup.2 /g; and steam treatment at 750.degree. C. for 17 hours, 
the surface area is 20 m.sup.2 /g. X-ray diffraction patterns of the 
sample before and after steam treatments are displayed in FIG. 1D. The 
diffraction line corresponding to the .about.20 .ANG. layer spacing is 
maintained after 650.degree. C. steaming, but disappears after steam 
treatment at 700.degree. or 760.degree. C., in conjunction with loss of 
most of the surface area. 
EXAMPLE 7 
An olefin isomerization reaction catalyzed by zirconia-pillared 
tetrasilicic mica 
Zirconia-pillared tetrasilicic mica (Zr-TSM) was prepared according to the 
procedure of Example 2 using 23 mmole Zr/g clay. Part of the sample was 
washed after calcination and recalcined. For a comparison, 
alumina-pillared tetrasilicic mica was prepared in a similar manner using 
aluminum chlorhydrol solution in place of the ZAA solution. The samples 
were characterized by measuring their layer repeat distance by X-ray 
diffraction and their surface areas by nitrogen adsorption. The results 
are given in Table V. The results for a standard .gamma.-Al.sub.2 O.sub.3 
catalyst that had been impregnated with 0.9% Cl have also been included 
for comparison. 
The solid acidity of the pillared clays was assessed by measuring the rate 
of isomerization of a model olefin, 2-methylpent-2-ene (2MP2), in the 
vapor phase over the pillared clay catalysts. The reactions were carried 
out in a standard fixed bed reactor equipped with a furnace for 
temperature control, flow controllers and saturators to control the feed 
stream, and an online gas chromatograph to identify the products of the 
reaction. Pillared clay samples (1 g) were pretreated at 500.degree. C. in 
500 cc/min H.sub.2 flow, and then purged with 500 cc/min He while cooling 
to 250.degree. C. 2MP2 (7% in He) was flowed over the catalyst at 
atmospheric pressure for one hour at 250.degree. C., then the temperature 
was raised to 350.degree. C. The conversions and product ratios measured 
at 350.degree. C. and 2 hour total time on stream are reported in Table V. 
The results of the 2MP2 isomerization tests show that the postcalcination 
wash enhances the acidity of the pillared micas. The sample of Zr-TSM that 
was not washed showed a 2MP2 conversion of 38.6% while the Zr-TSM after 
washing and recalcination gave a 2MP2 conversion of 65.2%. The 
distribution of the strengths of the acid sites in the solid is addressed 
by the rate ratios in Table V. The isomerization of 2MP2 to 
4-methylpent-2-ene (4MP2) requires only a hydrogen shift and can be 
catalyzed by a relatively weak acid site. The isomerization of 2MP2 to 
3-methylpent-2-ene (3MP2) involves a methyl shift and requires a 
moderately strong acid site. The isomerization of 2MP2 to 
2,3-dimethylbutene (23DMB) is a more extensive skeletal rearrangement and 
requires a strong acid site to facilitate it. The ratio of 3MP2/2MP2 shown 
in the results for the washed Zr-TSM shows a relatively large proportion 
of the acid sites in this material have a moderate level of acidity, while 
the low ratio 23DMB/2MP2 show that there are few acid sites of high 
strength. The acidity distribution in Zr-TSM is similar to that found in 
Al-TSM, and narrower than that found in Cl/Al.sub.2 O.sub.3 because there 
are relatively fewer strong acid sites. 
TABLE V 
__________________________________________________________________________ 
Conversion 
3MP2/ 
23DMB2/ 
Surface Area 
Layer Spacing 
(mol %) 
4MP2 
4MP2 (m.sup.2 g) 
(.ANG.) 
__________________________________________________________________________ 
Zr--TSM 38.6 0.40 
0.036 360 21.8 
calcined 
Zr--TSM 65.2 1.29 
0.13 394 21.7 
washed 
Al--TSM 38.5 0.50 
0.040 393 18.0 
calcined 
Al--TSM 73.2 1.89 
0.26 394 18.4 
washed 
0.9% Cl/Al.sub.2 O.sub.3 
67.8 1.44 
0.66 
__________________________________________________________________________