Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
t-
BACKGROUND OF THE INVENTION
2 1. Field of the Inventlon
3 The present invention relates to a catalyst and
4 its use in a catalytic cracking process. More particularly,
the prese~_ invention relates to a catalytic cracking cata-
6 lyst having improved activity and selectivity for producing
7 high octane number naphtha.
8 2. Des_rlption of the Pr _r Art
9 Hydrocarbon conversion catalysts comprising a
zeolite dispersed in a siliceous matrix are known. See,
11 for example, ~.S. Patent 3,140,249 and U.S. Patent 3,352,796.
12 A catalyst comprising a zeolite, an inorganic oxide
13 matrix and inert fines, which may be alpha alumina, is
14 known. See U.S. Patent 3,312,615.
15 A catalyst comprising an amorphous silica-alumina, ;
16 separately added alumina and a æeolite is known. See U.S.
17 Patent 3,542,670.
18 A catalyst comprising a zeolite, an amorphous hy-
19 drous alumina and alumina monohydrate is known. See U.S.
Patent 3,428,550.
21 To impro~e ~he steam and thermal stability o~
22 zeolites, it is known to produce zeolites having a low level
23 of alkali metal content and a unit cell size less than about
24 24.45 Angstroms. See U.S. Patents 3,293,192 and Re 28,629
(Reissue of U.S. Patent 3,402,996).
26 It is also known to treat hydrogen or ammonium
27 zeolite with H20 at a temperature ranging from about 800 to 1500F
~8 150nF, and subsequently cation exchanging the steam and
29 water treated zeolite with cations which may be rare earth
metal cations. The method increases the silica to alumina
31 mole ratio of the zeolite. See U.S. Patent 3,591,488.
32 U.S. Patent 3,676,368 discloses a rare earth ex-
33 changed-hydrogen faujasite containing from 6 to 14 percent
34 rare earth oxides.
~J-
~
1 U.S. Patent 3,9S7,623 discloses a rare earth ex
2 changed zeolite having a total of 1 to 10 weight percent
3 rare earth metal oxide.
4 U.SO Patent 3,607,043 discloses a process for pre-
S paring a zeolite having a rare earth content of 0.3 to 10
6 weight percent.
7 U.S. Patent 4,036,739 discloses hydrothermally
8 stable and ammonia stable Y zeolite in which a soaium Y
9 zeolite is ion exchanged to partially exchange sodium ions
for ammonium ions, followed by steam calcination and a
11 further ion exchange wi~h ammonium to reduce the final
12 sodium oxide content to below 1 weight percent, followed
13 by calcination of the reexchanged product, or according to
14 U.S. Patent 3,781,199, the second calcination may be con-
ducted after the zeolite is admixed with a refractory oxide.
16 SUMMARY OF T~E INVENTION
,
17 In accordance with the invention there is provided,
18 a catalyst comprising:
19 (a) an ultrastable Y-type crystalline alumino-
silicate zeolite;
21 (b) an inorganic oxide matrix, and
22 (c) discrete particles of alumina;
23 said zeolite prior to being composited with (b)
24 having a unit cell size not greater than about 24.5 Angstroms,
and said catalyst having a rare earth metal content such that
26 the ratio o weight percent rara earth metal, calculated as
27 the rare earth metal oxide, based on the tQtal catalyst,
28 divided by the weight percent zeolite based on the total
29 catalyst ranges from about 0.01 t~ about 0.08.
In accordance with the invention there is further
31 provided a catalytic cracking proce s utilizing ~he above
32 stated catalyst.
33 DETAILED DESCRIPTION OF THE INVENTION
34 The catalyst of the present invention must have a
,rare earth content such that the ratio of weight percent rare
36 earth metal oxide based on the total catalyst divided by the
37 weight percent zeolite based on the total catalyst ranges
from about 0.01 to about 0.08, preferably from about 0.01
to about 0.06, more preferably from about 0.01 to about 0.04.
The rare earth metal may be a single rare earth
metal or a mixture of rare earth metals of elements having
atomic numbers ranging from 57 to 71.
The alkali metal content of the total catalyst is
suitably less than about 0.6 weight percent, preferably less
than about 0.3 weight percent, calculated as the alkali metal
oxide, based on the total catalyst.
The required amount of rare earth metal can be
incorporated into the catalyst either by preparing a zeolite
having the required rare earth content and then compositing
the zeolite with a conventional matrix or the required amount
of rare earth in the catalyst can be obtained by utilizing
a zeolite having essentially no rare earth metal cations,
that is, less than 1 weight percent rare earth oxide, based
on the zeolite, or less than the requir~d amount of rare
earth metal and subsequently treating the composite catalyst
(that is, æeolite dispersed in a matrix) with a solution
comprising rare earth metal components to incorporate the
required amount of rare earth metal components into the
catalyst.
The Ultrastable Y-type Zeolite Com~onent
Ultrastable Y-type zeolites are well known. They
are described, for example, in U.S. Patent 3,293,192; U.S.
Patent Re 28,629 ~Reissue of U.S. Pa~ent 3,402~996); U.S.
Patent 4,036,739; U.S. Patent 3,781,199; U.S. Patent 4,036,739.
They are also described in the publication, Soci0ty of Chemical
Engineering (London) Monograph Moleculare Sieves, p. 186
(1968) by C.V. McDaniel and P.K. Maher. The term "ultrastable"
with reference to a Y-type zeolite refers to a z.eolite which
has improved resistance to degradation o crystallinity by
high temperature and steam treatment and is characterized by
an alkali metal content ~Na, K or any other alkali metal ion~
of less than
,, "
~-~'7~
-- 4 --
1 about 4 weight percent, calculated as the alkali metal oxide
2 based on the zeolite, a unit cell size not greater than
3 about 24.5 Angstroms, preferably not greater than about
4 24.4 Angstroms and a silica to alumina mole ratio of at
least about 3. The ultrastable Y-type zeolite is identified
6 both by the smaller unit cell size and the low level of
7 alkali metal cations. The particle size of the zeolite may
8 vary widely and is not criticalO u~ally, the particle size
9 of the zeolite ra~ges from about 0.1 to 10 microns in di-
ameter, preferably from about 0.5 to about 3 microns.
11 The æeolite may comprise rare earth metal cations
12 and may additionally comprise hydrogen cations and cations
13 of Group IB to VIII metals of the Periodic Table of Elements.
14 The Periodic Table referred to herein is given in andbook
of Chemistr~ and Physics, published by the Chemical Rubber
16 Company, Cleveland, Ohio, 45th Edition, 1964. When addi-
17 tional cations are present other than rare earth metals ~nd
18 alkali metals, the preferred additional cations are calcium,
19 magnesium, hydrogen and mixtures thereof. The concentration
of hydrogen present in the finished zeolite will be that
21 concentration equivalent to the difference between theoreti-
22 cal cati~n concentration of the particular zeolite in ques-
23 tion and the amount of cation present in the form of, for
24 example, rare earth and residual alkali metal ion.
When the rare earth content and low alkali metal
26 of the catalyst axe controlled by utilizing a xeolite which
27 has been treated to comprise at least a portion of the re-
28 quired rare earth metal, for example, as rare earth metal
29 cations, the zeolite having the desired rare earth metal
component can be obtained by various methods.
31 One method of producing a required zeolite having
32 only a limited amount of rare earth metal cations and low
33 alkali metal content is to start with an ultrastable Y-type
34 zeolite having a unit cell size not greater than about 24.5
Angstroms, preferably not greater than about 24.4 Angstroms,
36 having less than 4 weight percent alkali metal, calculated
37 as the alkali metal oxide, based on the zeolite, and contact
the ultrastable Y-type zeolite with a fluid medium comprising
rare earth metal cations of a single rare earth metal or cations
of a mixture of rare earth metals. The ion exchange is
conducted in a conventional way such as by utilizing salts of
the desired rare earth metals. Ion exchange methods are well
known in the art and are described, for example, in U.S.
Patent 3,140,249; U.S. Patent 3,140,251; U.S. Patent 3,140,253.
The amount of rare earth metal used is such that
it does not exceed the limits of the range required for the
catalyst of the present invention. The total amount of re-
quired rare earth may be exchanged into the zeolite itself
or only a portion of the amount required by the catalyst of
the present invention may be exchanged into the zeolite and
the balance of the desired required amount may be composited
with the finished catalyst, for example, by posttreating the
finished catalyst with a solution comprising rare earth metal
components that become associated with the finished catalyst.
The rare earth-exchanged zeolite is recovered, for
example, by-filtration, and washed with water to remove solu-
ble ma~ter and calcined, for example, at a temperature rangingfrom about 700F to 1600F for about 0.5 to 6 hours, preferably
from about 900F to 1200F for about 1 to 3 hours in the
presence of H2O which may be steam or water.
The final zeolita may be composited with other
catalytic metal components, such as metals of Gro~ps IIA,
IIIA, IVA, IB, IIB, IIIB, IVB, VIB, and ~III of the Periodic
Table of Elements.
The particle size of the zeolite component will
generally range from abou~ 0.1 to 10 microns, preferably from
about 0.5 to 3 microns. Suitable amounts of the zeolite
component in the totaI catalyst will range from about 1 to
60, preferably from about 1 to 40, more preferably from about
5 to 40, most preferably from about 8 to 35 weight
7~ 0~
-- 6 --
1 percent, based on the total catalyst.
2 The Alumina Com~onent
3 The catalyst of the present invention, optionally,
4 comprises a porous alumina component. The porous alumina
component is present in the preferred catalyst of the present
6 invention.
7 The porous alumina component of the catalyst of
8 the present invent~vn comprises discrete particles of var-
9 ious porous aluminas, preferably crystalline alumina, which
are kno~n and commercially available. In general, the por-
11 ous alumina component of the catalyst of the present in~
12 vention are discrete particles having a total surface area,
13 as measured by the method of Brunauex, Emmett and Teller
14 (BET) greater than about 20 square meters per gram (m2/g),
preferably greater than 145 m2/g, for examplP, fro~ about
16 145 to 300 m2/g. Preferably the pore volume (BET) of the
17 alumina will be greater than 0.35 cc/g. The average parti-
18 cle size of the alumina particles would generally be less
19 than 10 microns, preferably less than 3 microns. Prefer-
ably, the porous alumina will be a material having init-
21 ially, if used alone, prior to being composited with the
22 other components, inherently less catalytic cracking ac-
23 tivity of its own than the inorganic matrix component of
24 the catalyst. Preferably, the porous alumina will be a
bulk alumina. The term "bulk'l with reference to the por-
26 ous alumina is intended herein to designate a material which
27 has been preformed and placed in a physical form such that
28 its surface area and pore structure are stabilized so that
29 when it is added to an impure, inorganic gel containing
considerable amounts of residual soluble salts, the salts
31 will not alter the surface and pore characteristics measur-
32 ably nor will they promote chemical attack on the preformed
33 porous alumina which could undergo change. For example,
34 addition of "bulk" alumina will mean use of a material which
has been ~ormed by suitable chemical reaction, the slurry
36 aged, filtered, dried, washed free of residual sal~ and
37 then heated to reduce its volatile content to less than
'7~
7 --
1 about 15 weight percent. The porous alumina component may
2 suitably be present in the catalyst of the present inven-
- 3 tion in an amount ranging from about 5 to about ~0 weight
4 percent, preferably from about lO to about 30 weight percent,
based on the total catalyst. Alternatively and optionally,
6 an alumina hydrosol or hydrogel or hydrous alumina may be
7 used initially in the catalyst preparation as precursor of
8 the discrete particles of alumina in the finished catalyst.
9 The Inorganic Oxide Matrix Component
The inorganic oxide matrices suitable as component
11 of the catalyst of the present invention are amorphous cata-
12 lytic inorganic oxides, ~uch as silica, alumina, silica-
13 alumina, silica-zirconia, silica-magnesia, alumina-boria,
14 alumina-titania and the like and mixtures thereof. Prefer-
ably, the inorganic oxide matrix is a silica-containing
16 gel; more preferably the inorganic oxide gel is an amorphous
17 silica-alumina component such as a conventional silica-
18 alumina cracking catalyst, several types and compositions
l9 of which are commercially available. These materials are
generally prepared as a cogel of silica and alumina or as
21 alumina precipitated on a preformed and preaged hydrogel~
22 In general, the silica is present as a major component in
23 the catalytic solids present in said gels, being present
24 in amounts ranging from about 55 to lO0 weight percent;
preferably the silica will be present in amounts ranging
26 from about 70 to about 90 weight percent. Particularly
27 preferred are two cogels, one comprising about 75 weight
28 percent silica and 25 weight percent alumina and ~he other
29 camprising about 87 weight percent silica and 13 weight
percent alumina. The inorganic oxide matrix component may
31 suitably be present in the catalyst of the present invention
32 in an amount ranging from about 40 to about 99 weight per-
33 cent, preferably from about 50 to about 80 weight percent,
34 based on the total catalyst. It is also within the scope
35 of this invention to incorporate in the catalyst other mat- ;
36 erials, to be employed in cracking catalysts such as various
37 other types of zeolites, clays, carbon monoxide oxidation
63~
- 8
l promoters, etc.
2 The catalyst of the present invention may be pre-
3 pared by any one of several methods. The preferred method
4 of preparing one of the catzlysts of the present invention,
that is, a catalyst compri~ing silica-alumina and porous
6 alumina, is to react sodium silicate with a solution of
7 aluminum sulate to form a silica/alumina hydrogel slurry
8 which is then aged to give the desire~ ore properties,
9 filtered to remove a considerable amount of the extraneous
and undesired sodium and sulfate ions and then reslurried
11 in waterO Separately, the bulk alumina is made, for ex- ~
12 ample, by reacting solutions of sodium aluminate and aluminum
13 sulfate under suitable conditions, aging the slurry to give
14 the desired pore properties of the alumina, filtering, dry-
ing, reslurxying in water to remove sodium and sulfate ions
16 and drying to reduce volatile matter content to less than
17 15 weight percent. The alumlna is then slurried in water
18 and blended in proper amounts, with a slurry of impure
19 silica-alumina hydrogel.
The zeolite component is added to this blend. A
21 sufficient amount of each component is utilized to sive the
~2 desired final composition. The resulting mixture is then
23 filtered to remove a portion of the remaining extraneous
24 soluble salts therefrom. The filtered mixture is then dried
to produce d~ied solids. The dried solids are subsequently
26 reslurried in water and washed substantially free of the
27 undesired soluble salts. The catalyst is then dried to a
28 residual water content of less than about 15 weight percent.
29 The dried ca~alyst is reco~ered. The catalyst of ~he pres-
ent invention is particularly suited for use in catalytic
31 cracking of hydrocarbons.
32 Catalytic cracking with the catalyst of the pres-
33 ent invention can be conducted in any conventional catalytic
34 cracking manner. Suitable catalytic cracking conditions in-
clude a temperature ranging from a~out 700F to about 1300F
36 and a pressure ranging from about subatmosphexic to several
37 hundreds of atmospheres, typically from about atmospheric
. .
,: ' ;
~ 7~3~
g
1 to about 100 psig. The process may be carried out in a
2 fixed bed, moving bed, ebullating bed, slurry, transferline,
3 or fluidized bed operation. The catalyst of the present
4 invention can be used to convert any of the conventional
hydrocarbon feeds used in catalytic cracking, that is, it
6 can be used to crack naphthas, gas oil and residual oils
7 having a high content of metal contaminants. It is es-
8 pecially suited for cracking hydrocarbons boiling in the
9 gas oil range, that is, hydrocarbon oils having an atmos-
pheric pressure boiling point ranging from about 450 to
11 about 1100F to yield not only products having a lower
12 boiling point than the i~itial feed but also a naphtha
13 product having an improved octane nu~ber.
14 DE5CRIPTION OF THE PREFERRED EMBODIMENTS
The following examples are presented to illustrate
16 the invention.
17 EXAMPLE 1
18 A large sample of a catalyst, herein designated
19 catalyst A, was divided into 5 equal portions. Catalyst A
comprised 20 weight percent ultrastable Y type zeolite, 20
21 weight percent of discrete particles of porous alumina dis-
22 persed in a matrix of 60 weight percent silica-alumina gel
23 based on the total catalyst (75 weight percent silica and
24 25 weight percent alumina). One portion was left unreacted.
The remaining four portions were treated to different levels
26 of rare earth metals by post-exchange, that is, by treating
27 the composite catalyst. Post-exchange ~as accomplished by
28 slurrying one part of catalyst by weight with 3 parts o~
29 water by weight. Enough nitric acid was added to adjust
the slurry pH to between 6.0 and 6.5 and the slurry was
31 heated to 135F. A mixed rare earth chloride solution ~as
32 then added to the slurry to achieve the desired ~evel of
33 exchange. The rare earth solution contained the equivalent
34 of 484 grams of rare earth oxide per liter of solution.
Aiter the rare earth solution had been added, the slurry
36 was heated and stirred an additional 60 minutes. The wet
37 cake was then dried and calcined. This procedure was used
~7~
-- 10 --
1 to produce four catalys~s, catalysts B, C, D and E, that
2 differed from the parent catalyst only in the amount of
3 rare earths added. A11 of the catalysts were then steamed
4 16 hours at 1400F to simulate the deactivation that would
occur in a commercial cracking unit. The catalysts were
6 then evaluated in two ways. Each was tested for activity
7 using the standard microactivity test ~MAT~. Each catalyst
8 was also evaluated us,~ a circulating fluidized bed cata-
9 lytic cracking unit with reactor and regenerator vessels.
The feed used in this test is described in Table I. The
11 operating conditions are described in Table II. Yield and
12 product quality data from this test are given in Table III
13 along with the rare earth levels and microactivity test
14 results. It can be seen from Table III that as rare earth
level increases, activity and naphtha yields also increase.
16 Coke and gas yields decreased. These very desirable effects
17 are accomplished at some small loss in clear octane number.
18 _The octane number loss did not become significant until the
19 ratio of rare earth oxide to zeolite as defined on page 2,
was over 0.08.
21 Catalysts B and C are catalysts in accordance
22 with the present invention. Catalysts A and D are not cata-
23 lys~s in accordance with the present invention.
1TABLE I
2VACUUM GAS OI~ _EED INS_ CTIONS
3 Gravity,API at 50F 22.5
4 Molecular weight 530.0
Carbon/hydrogen, wt. % 86.6/12.3
6 Sulfur, wt. % 1~243
7 Nitrogen, ppm 746
8 Conradson carbon, wt. % 0.44
9 ~5etals, wppm
Fe 5-5
11 Ni 0.28
12 V 0.33
13 Bromine No. cgm/gm 5.16
14 Aniline Point, F 183
Pour Point, F 98
16 Refractive index at 67C 1.4937
17 Distill tion, F at Vol. % Off
18 5% 636
19 10/~0 671/721
~0/40 753/785
21 50 816
22 60/70 854/891
23 80/90 928/976
24 95~ 1015
s
1 TABLF II
2 OPE~ATING CONDITIONS
3 Reactor
4 Temperature, F 925
Catalys~/oil wt. ratio 4.0
6 Feed rate(l), W/Hr/W 15 to 30
7 ~2~
8 Temperature, F 1100 to 1125
9 Carbon remaining on catalyst, wt. ~ 0.05 to 0.25
--
(1) Varied to change conver ion
-- 13 --
oo
C~ ~p O o~
a~ ~ ~ ~ Ul ~r _I a)
Clo ~r o~ N
. . o ~ ~ ~ ~ o ~ r-
O t~ I` o ~J er ~,9 cn t-- dP
P~
~D a~
o C~ . o ~ CO ~
~ ~ O
O O 1` o ~ e~
.,
U~ ~ ~ ~ ~D
E~ .~ ~ ~D ~1 ~ O CD
U~ ~ ~ o ~ o C~
o
~_1 O O ~D O
~td
E~ ~ ~ ~
l¢ ~ h
C)
a . ,
~,~ r~ Ln ~ a~ o
~ U~ ~ O ~D U~ . ~ ~0
H Z e~ co ~ O O
H ,cc `P O O ~ O tN
H 5: ~ O
:: ~ X O
~ ~ ~ ~ 0~ ~ ~: O
~ U~ t~l O U~ ~
O ~ rl
~i ~ ~ RC) ~
~, oP a) aJo h
E~ o ? ~au, n~
~ ~ ~ ~ .
A~ Ul O X~ u~ f-l h
IL~ ~ ~ C,) OQ) ~t.) 0
~) 0 d~. f~
;~ to ~ ~1 o\~ ~ S~ R
O a
O ~: ~ .
~1 ~ æ ~
O
~D ~ ~ ~ ~
o ~ a) ~ ~ u ~ z
a ~ ~ ~ ~ o ~
o ~ U~ ~ ~ ~ ._ ~--I U . o
0 ~ O ~P S ~ ~ h 0 rl ~ ~
u~ a) oP~ a ~ ~ ~ O E~ zrl O
h ~,
~3 3 ~> ~ ~ 3 ~1~4 a~ rl ~ 0
tq ~:: ~ 3 ~ 3o O E~ ta U1 JJ
~ ` O ~ ~ ~ Z Z ~
,~s o o ~a ~ o f'~ ~r O O
IJ t~O ~ `~ ~; ~ ~ ~
al E~ u~l f~
C) p~ P4 C,) I ~
~ ~7~ ~3
- 14 -
1 EXAMPI~ 2
2 Two catalysts, catalysts E and F, were prepared
3 and the composite catalyst E was post treated (post-exchanged)
4 with a rare earth metal salt solution in a manner similar to
that described in Example 1. The catalysts E and F com-
6 prised 25 weight percent ultrastable Y type zeolite, 20
7 weight percent of discrete particles bulk porous alumina,
8 dispersed in a matrix of 55 weight percer,~ ~Dased on totzl
9 catalyst) silica alumina gel. The catalysts were evalua_ec
in a microactivity test ~MAT) and also in the same catalyt-c
11 cracking unit described in Example 1. Feed and operatins
12 conditions were the same as given in Tables I and II.
13 The results of these tests are summarized in
14 Table IV.
TABLE IV
16 ~ y~ E F
__
17 RE2O3, wt. %(1) 0.067 0
18 Na2O, wt. ~ on total catalyst 0.15 0.24
19 RE2O3 on total cataiyst, wt. % 1.34 0
20 MAT Conversion, LV % 73.2 65.1
21 Product Yields at 65% Conversion
.
22 ~2~ wt. ~ on feed 0.029 0.030
23 Coke, wt. % 2.6 2.6
24 C3 , wt. % ~.5 4.5
25 ~/430F naphtha, vol. % 61.0 59.4
26 RON Clear 92.2 92.4
27 MON Clear 79 3 79.9
28 (1) Wt. % rare earth metal oxide based on total catalyst
29 divided by wt. % zeolite on total catalyst.
Catalyst E is a catalyst in accordance with the
31 present invention. As can be seen from the data of Table
32 IV, at a rare earth metal oxide to zeolite ratio of 0.067,
33 there is only a slight decrease in octane number.
. .
7~ ~?5~
- 15 -
1 EXAMæL~ 3
2 Three catalysts (catalysts H, I, J) comprising
3 rare earth metal oxides at different levels were compared
4 with a reference catalyst (herein designated catalyst G).
All 4 catalysts comprised 20 weight percent ultrastable Y
6 zeolite, 20 weight percent alumina in the form of discrete
7 particles dispersed in a matrix of 60 weight percent (based
8 on total catalyst) silica-alumil.a gel (75 wt. ~ silica; 25
9 wt. % alumina). Catalyst H was prepared by the post exchange
o~ the composite catalyst procedure described in Example 1.
11 Catalysts I and J were prepared by pre~exchanging only the
12 ultrastable Y zeolite with a mixed rare earth chloride solu-
13 tion prior to adding the zeolite to the other catalyst com-
14 ponents. Catalysts H and J are catalysts in accordance
with the present invention. Catalysts G and I are not
16 catalysts of the present invention. After the rare earth
17 exchange step, the ultrastable Y zeolite was washed with
18 water and then calcined 2 hours at 1000F to ensure that
19 the rare earth ions would remain in the ultrastable Y zeo-
lite during the subsequent catalyst preparation steps.
21 Catalysts G, H, I and J were evaluated using the same pro-
22 cedure described in Example 1 except that catalyst J was
~23 not tes-ted in the fluidized bed catalytic cracking unit.
24 The data obtained are summarized in Table V.
As can be seen from Table V, catalyst J compares
26 favorably with catalysts at the same weight percen~ RE2O3
27 prepared by post exchanging the composite catalyst. Catalyst
28 I showed no advantage over catalyst G which contained zero
29 rare earth. The rare earth level of cataIyst I was too low
to change significantly the M~T conversion or the product
31 yields and quality.
5S;
-- 16 --
." O`P
L~ ~ ~ cr~
~I c
. . . . ~ I I I I I I ~
o o o ~r r I I I I I 1 3
o r-- U~ er ~ In~O N ~1
HO O 1--l 0 O ~ I` ~ . ~rl
. . . r~C) ~) O
OOOO~DOtllLt)U~a~co
.
co ~7 ~ ~ o t~
O ~ ~ ~ O O~
. ~ 0
O O O ~ ~D O ~ e!~
O
` ~~ ~ O ~ ~D . . ~ I
E':l ~ O
o o o o u:~ o ~ 11-) u~ a-
E~ ~
:
~0 ~ :
; ' : O
~ : ~ .
~ ~ S~ ~
: _ C) ~ 3 ~ ~ : ta o
~1 ~ 3 ~ o~ ,C
d, .'- ~ ~1 ~1 ~P R :
tO O dP . ~ h h
~ 1 ~ ' ~ ~ ~ ~
' 3 .L) C~ a~ dP O
:~ ` O O 3 ' o N
_, . ,., ~ ~ . æ z; 3
~1 O O ~1 0 ~ ~ O ~ er O O
E~ O ~ C~ C) ~ ~ ~ _
0 ~1 ~d O ~ I¢ h Ln ~-1
; k ~:1; ~ ~ ~) I _
. ~ :
'.
' ",: ; `
.
,
