Method for preparing rare earth metal catalysts with honeycomb-like alloy supports and catalysts obtained thereby

This invention relates to a method for preparing rare earth metal catalysts with a honeycomb-like alloy support and catalysts obtained thereby, which method comprises: preparing a corrugated, perforated metal alloy support tape, coating the support tape with a solution of a mixture of light rare earth metal salts; drying the support tapes; decomposing and oxidizing the rare earth metal salts into catalytic materials having a perovskite or a spinel type crystal structure.

FIELD OF THE INVENTION 
This invention relates to a method for preparing rare earth metal catalysts 
with a honeycomb-like alloy support and catalysts obtained thereby. More 
particularly, this invention relates to a fast coating and drying method 
for preparing rare earth metal catalysts with a honeycomb-like alloy 
support and catalysts obtained thereby. The resulting catalysts are 
suitable for use in the purification of industrial waste gases, exhaust 
gases from automobiles as well as in purification of air. 
BACKGROUND OF THE INVENTION 
Much effort has been expended in recent years in impoving the performance 
of catalysts, reducing their cost and extending their useful life. 
In a known method for preparing the catalysts, ceramic materials or high 
temperature-resisting aluminum-containing alloy materials, which generally 
include silica, ceramic compositions, natural silicious materials, 
alundum, silicon carbide, titania and zirconia etc., are used as catalyst 
supports with noble metals being used as the catalytic materials. However 
because noble metals are rare and expensive, the cost of the resulting 
catalysts are also expensive. Presently known rare earth metal catalysts 
are generally formed by impregnating the ceramic support structure with a 
solution of a mixture of rare earth metal salts, then drying and calcining 
the impregnated supports. In this method, the catalytic materials are not 
coated firmly and uniformly onto the supports in strict stoichiometric 
proportions, therefore, one can not obtain a predetermined level of 
catalytic activity. Other known methods for coating a catalytic materials 
onto supports comprise co-deposition, chemical plating, spray drying, 
metallurgical consolidation, freeze drying, and the like. However, all 
these methods are unsatisfactory because the catalytic activity can not be 
predetermined and the catalysts produced have a short useful life. 
SUMMARY OF THE INVENTION 
Thus, an object of the present invention is to provide a method for 
preparing rare earth metal catalysts with a honeycomb-like alloy support 
capable of overcoming the afore-mentioned drawbacks of the prior art. 
Another object of the present invention is to provide a new method for 
coating a catalytic materials onto the support firmly and uniformly in 
stoichiometric proportions forming desired chemical structures. 
A further object of the present invention is to provide rare earth metal 
catalysts with a honeycomb-like alloy support prepared by the method 
according to the present invention, which catalysts have the advantages of 
high catalytic activity, good thermal stability, lower cost and a long 
useful life. 
The present invention provides a method for preparing rare earth metal 
catalysts with a honeycomb-like alloy support comprising the following 
steps: (1) preparing an alloy support tape; (2) rapidly coating the 
surfaces of the support with a solution of a mixture of rare earth metal 
salts; (3) heating the coated support tape to dry and to decompose the 
rare earth metal salts; (4) oxidizing the rare earth metals into composite 
oxides having desired chemical structures; and (5) forming the support 
tape coated with catalytic materials into desired shapes and sizes. 
Alternatively, step (5) may be carried out prior to step (4). 
The support used in the present invention is a Fe-Cr-Al alloy or Ni-Cr-Al 
alloy tape with high thermal stability and electrical resistance. The 
catalytic materials used in the present invention are rare earth metal 
composite oxides having perovskite-type crystal structure (ABO.sub.3) or 
spinel-type crystal structures (A.sub.2 BO.sub.4) comprising mixed light 
rare earth metals and iron. The catalysts prepared by the method according 
to this invention have high catalytic activity, high thermal stability, 
high resistance to lead poisoning and a long useful life.

DETAILED DESCRIPTION OF THE INVENTION AND THE PREFERRED EMBODIMENTS 
The support of the present invention is made of activated tapes prepared 
from Fe-Cr-Al alloy or Ni-Cr-Al alloy strips with high thermal stability 
and electrical resistance. The activated tapes are prepared as shown in 
FIG. 1. The alloy strips are rolled into long tapes with a thickness of 
about 0.5-0.12 mm, preferably about 0.07-0.08 mm, and a desired width of 
from about 25 mm to 50 mm. The resulting long tapes are perforated 
intermittently, preferably at distances of about 1.1 mm to 1.2 mm apart, 
from both the top and bottom surfaces to form small holes of preferably 
about 0.4 mm.times.0.4 mm with metal burrs. The penetration of the small 
holes should be more than or equal to 90%. The tapes may then be crimped 
into corrugated tapes with a wavy structure having a wave height of 
preferably about 1.0-2.0 mm with a distance of preferably about 2-3 mm 
between adjacent waves. The tapes are then subjected to degreasing, acid 
etching, roughening and heat activating treatments, to form a protective 
layer of .gamma. -Al.sub.2 O.sub.3 on their surfaces. 
In comparison with the metal supports in the prior art, the supports of the 
present invention have small holes with metal burrs. This latter feature 
provides increased absorbance and higher specific surface area to the 
supports of the present invention. Moreover, during heat treatment, metal 
bonds can be formed between the surfaces of the supports and the catalytic 
materials, to firmly bond the catalytic materials onto the surfaces of the 
supports. 
In addition, the high thermal stability and electrical resistance of the 
supports used in the present invention permit the catalysts to be 
electrically activated by applying a voltage to the support. After 
activation, the surfaces of the supports rapidly reach a temperature 
sufficient to initiate the catalytic reaction. Thus, the waste gas 
preheaters necessary to a prior art catalytic apparatus can be eliminated 
and the cost of the catalytic purifying apparatus of the present invention 
is reduced. 
The catalytic materials sutiable for use in the present invention are rare 
earth metal composite oxides having perosvkite-crystal structures 
(ABO.sub.3) or spinel-type crystal structrues (A.sub.2 BO.sub.4). 
Generally, in the composite oxides of either crystal structures, A type 
cations are metals of atomic number 11-16, 56-71 or 89-103, and B type 
cations are metals of variable valence having ionic radii between about 
0.4 angstroms and 1.4 angstroms. In ABO.sub.3 type structures, the total A 
type metal cations should be equal to the total of B type metal ions of 
variable valence. In A.sub.2 BO.sub.4 structures, the total A type cations 
should be equal to twice the total of B type cations. In both types of 
structures, the total of charges of A type and B type cations should be 
equal to the total of the charges of the oxygen ions. 
In the composite oxides having ABO.sub.3 structures according to the 
present invention, of the sites of A, from about 60% to 80% are occupied 
by cations of mixed light rare earth metals or lanthanum, and from about 
40% to 20% are occupied by cations of an alkaline earth metal selected 
from the group consistng of strontium, calcium and mixtures thereof; of 
the sites of B, from about 50% to 80% are occupied by cations of iron, and 
from about 50% to 20% are occupied by cations of a metal selected from the 
group consisting of manganese, copper, nickel, and mixtures thereof. When 
a lower initial temperature for the catalytic reaction is desired, a small 
amount of palladium may be added, i.e. about 1% of the sites of B may be 
occupied by palladium. 
In the composite oxides having A.sub.2 BO.sub.4 structures according to the 
present invention, of the sites of A, from about 70% to 90% are occupied 
by cations of mixed light rare earth metals or lanthanum, and from about 
30% to 10% by cations of an alkaline earth metal selected from the group 
consisting of strontium, calcium, and mixtures thereof; and of the sites 
of B, from about 50% to 80% are occupied by cations of iron, and from 
about 50% to 20% are occupied by cations of nickel. 
The catalytic materials useful in the present invention can be formulated 
as follows: 
EQU [RE.sub.(1-x) Sr.sub.x ][Fe.sub.(1-y)Mn.sub.y ]O.sub.3, or 
EQU [La.sub.(1-x) Sr.sub.x ][Fe.sub.1-y-w) Mn.sub.y Pd.sub.w ]O.sub.3 
EQU [RE.sub.(2-a-b) Sr.sub.a Ca.sub.b ][Fe.sub.(1-z) Ni.sub.z ]O.sub.4 or 
EQU [La.sub.2-a-b) Sr.sub.a Ca.sub.b ][Fe.sub.(1-z) Ni.sub.z ]O.sub.4 
wherein x=0.2-0.4, y=0.2-0.5, w=0.01, a=0.1-0.3, b=0.1-0.3, z=0.2-0.5. The 
values indicated hereinabove are approximate values and RE indicate that 
it is a rare earth element or a mixture of rare earth elements. 
In the present invention, the composite oxides of rare earth metals useful 
as catalytic materials are relatively loosely packed, and the surfaces of 
the supports have many small holes. Thus, the catalysts of the present 
invention behave like porous sound absorbing materials. The sound waves 
cause the air in the voids of the materials to vibrate and there is 
friction of the air with the walls in the voids. As a result, sound energy 
is converted into thermal energy and noise is reduced. When several blocks 
of catalysts are placed in spaced intervals, the gas flow therethrough 
suddenly deffuses as it passes from one catalyst block to another. Thus, 
in accordance with the principle of millipore amplified erasure the 
catalysts of the present invention also functions to reduce or eliminate 
noise, and can be used as a muffler. 
The method for preparing a catalyst of the present invention is described 
here below more specifically with reference to the accompanying drawings. 
The catalysts according to this invention can be prepared in a continuous 
manner by the use of the apparatus shown in FIG. 2. First, two differently 
shaped tapes, such as a corrugated support tape, and a flat support tape 
are rolled up respectively on shaft (21) and shaft (22) and fed 
simultaneously at a fixed speed in the range of 1 to 2 m/min. The tapes 
are passed through a tank containing a solution of a mixture of rare earth 
metal salts and is coated uniformly. The speed at which the support tapes 
are fed through the coating tank (23) is such that the support tapes are 
in the coating tank for a period of about 0.5-30 sec. If the first coating 
is not sufficiently thick or uniform, the support tapes may be re-coated. 
Thereafter, the coated support tapes are immediately fed into a drying 
section (24) of the coating kiln set at a temperature in the range of 
about 110.degree. C. to 200.degree. C. The interval between the coating 
step and drying step is not more than 120 sec. The tapes are then fed into 
a salt decomposing section (25) at a temperature set in the range of about 
350.degree. C. to 450.degree. C. and subsequently into a primary oxidizing 
section (26). In the primary oxidizing section (26), catalytic materials, 
which are to be converted to an ABO.sub.3 -type crystal structure, are 
oxidized at a temperature of from about 650.degree. C. to 750.degree. C.; 
whereas, catalytic materials which are to be converted to an A.sub.2 
BO.sub.4 type crystal structure are oxidized at a temperature from about 
800.degree. C. to 850.degree. C. Thereafter, the support tapes coated with 
catalytic materials are rolled up on shaft (27) and shaft (28) 
respectively, or the tapes may be rolled up together on one shaft, (27) or 
(28). The resulting support tapes coated with catalytic materials can be 
formed into catalysts with desired shapes and sizes, such as cylinders or 
blocks. The shaped catalysts (32) are then discharged into a carriage (33) 
and passed through a preheating section (35) in a period of about 30 min. 
at a temperature in the range of about 350.degree. C. to 450.degree. C., 
then through a secondary oxidizing section (36) in a period of about 90 
min. at the same temperature range as the primary oxidizing section (26) 
and subsequently through a cooling section (37) in a period of about 30 
min. Alternatively, after the salts are decomposed, the support tapes 
loaded with catalytic materials may be passed through a long oxidizing 
section in a period of about 60 min., cooled, and then form into shaped 
catalysts as desired. 
The catalysts prepared by the above-said method according to this invention 
have high catalytic activity, a long catalytic life and are low in cost to 
manufacture. 
The following examples illustrate the invention and are not to be construed 
as limiting the scope thereof. 
EXAMPLE 1. 
Preparation of Activated Support Tapes 
As shown in FIG. 1, a Fe-Cr-Al alloy (OCr.sub.21 Al.sub.6) strip with a 
thickness of 1.0 mm is rolled several times with a two-roller mill (1) and 
a four-roller mill (2) to attain a thickness of about 0.07-0.08 mm. The 
composition of the Fe-Cr-Al alloy is as follows (by weight based on the 
total weight of the alloy): Cr:21-24%, Al:6.5-7.5%, rare earth metals: 
0.03%, Ti:0.15%, Co:0.5%, C less than or equal to 0.06%, Si less than or 
equal to 0.06%, Mn less than or equal to 0.06%, S less than or equal to 
0.03%, P less than or equal to 0.03%, with the balance being Fe. 
The Fe-Cr-Al alloy has the following characteristics: a maximum operating 
temperature of up to 1200.degree. C., a coefficient of elongation of 
greater than or equal to 12%, a cold bend for 90% of greater than or equal 
to 5 bendings, a specific electrical resistance of 
1.4.+-.0.1.OMEGA.mm.sup.2 /M, and an annealing temperature of about 
800.degree..+-.20.degree. C. 
The resulting metal tape is perforated at intervals of about 1.2 mm with a 
perforator (3) to contain small holes having metal burrs on both surfaces. 
The size of the holes is about 0.4 .times.0.4 mm, and the penetration of 
the holes is greater than or equal to 90%. Part of the resulting tape is 
then rolled by a crimping machine (4) to form a corrugated tape with a 
wavy structure having a wave distance between adjacent waves of about 3 
mm, and a wave height of about 1.1-1.7 mm. 
Thereafter, the resulting alloy tape is subjected to the following 
treatments to form an oxide layer on the surfaces. The treatments include 
(a) degreasing with a degreasing agent (7) in degreasing tank (6) at 
50.degree. C., (b) washing with water in tank (8), (c) acid etching in 
tank (9) with 38% industrial hydrochloric acid for about 5-8 min., (d) 
water washing in tank (10), (e) cleaning with deionized water (12) in an 
ultra-sonic cleaner (11), and (f) activating in a kiln (13) at a 
temperature in the range of 650.degree.-750.degree. C. The abovementioned 
treatments are carried out continuously. 
EXAMPLE 2. 
Preparation of Catalysts 
234.8 grams of lanthanum nitrate, 63.49 grams of strontium nitrate, 318,93 
grams of iron nitrate, 35.79 grams of manganese nitrate and 2.30 grams of 
palladium nitrate are dissolved in water and mixed homogeneously to form 
2000 ml of solution. The solution was charged into tank (23) of the 
coating apparatus as shown in FIG. 2. The drying section of the fast 
coating kiln was controlled at a temperature in the range of about 
150.degree. C., the salts decomposing section of the fast coating kiln was 
controlled at a temperature in the range of about 400.degree. C., and the 
primary oxidizing section was controlled at a temperature in the range of 
about 700.degree. C. 
Two activated support tapes, one being corrugated and one being flat, 
prepared according to Example 1 were simultaneously fed out of shafts (21) 
and shaft (22) respectively, and passed through the fast coating apparatus 
at a fixed speed in the range of about 1.5 m/min., resulting in a coating 
time of about 0.5 sec. The coated support tapes were then passed through 
the drying section, the salt decomposing section and the primary oxidizing 
section. Afterwards, the resulting support tapes having two different 
shapes were rolled on one shaft, (27) or (28), to form catalysts with 
cylindrical shapes. The cylindrical shaped catalysts were discharged into 
carriage (33), and then passed through the oxidizing kiln at a temperature 
in the range of about 700.degree. C. for about 1.5 hours. About 4-5 kg of 
the catalyst with the following stoichiometry, [La.sub.0.7 Sr.sub.0.3 
][Fe.sub.0.79 Mn.sub.0.2 Pd.sub.0.01 ]O.sub.3, as the catalytic material 
was obtained. The catalytic material was about 7-8 percent by weight of 
the catalyst. 
The suitability and efficiency of purification of this catalyst are shown 
in FIGS. 3, 4 and 5. The graphs comparing this catalyst with a noble metal 
palladium catalyst as the catalytic material (with the same support) are 
shown in FIGS. 6, 7 and 8. The performance of this catalyst in purifying 
air contained in a steel bottle is shown in FIG. 9. The space velocity 
character and acoustic absorption coefficient are shown in Tables 1 and 2. 
TABLE 1 
______________________________________ 
Propylene Purifying Efficiency (%) And Space Velocity 
catalyst of the catalyst with 0.1% 
waste gas 
present invention 
by weight of Pd 
space ve- 
inlet temperature (.degree.C.) 
locity (h.sup.-1) 
200 300 400 500 200 300 400 500 
______________________________________ 
40000 9.7 87.5 82.4 87.2 21.5 56.6 72.0 79.2 
30000 22.9 93.3 92.9 91.2 38.0 54.7 79.7 89.4 
20000 58.2 100 92.9 97.9 54.0 54.0 87.5 93.3 
10000 66.7 100 99.4 100 70.0 73.6 100 100 
5000 64.0 100 100 100 78.5 90.7 100 100 
______________________________________ 
Note: 
The waste gas contains 1% by weight of C.sub.3 H.sub.6 and 0.2% by weight 
of CO. 
TABLE 2 
__________________________________________________________________________ 
Coefficient of Acoustic Absorption of Catalysts 
wave 
air 
height 
thickness 
acoustic frequency (HZ) 
shape (mm) 
(mm) 125 
250 
500 
100 
1800 
2000 
4000 
__________________________________________________________________________ 
.phi. 98 mm, thickness 
1.7 -- 0.09 
0.07 
0.09 
0.09 
-- 0.34 
0.55 
0.07 mm thick, 
corrugated sheet 
.phi. 98 mm .times. 50 mm 
1.1 2.1 0.09 
0.12 
0.21 
0.42 
0.44 
catalyst having 
2.0 1.5 0.09 
0.18 
0.25 
0.48 
0.54 
honeycomb shape 
2.3 0.7 0.10 
0.13 
0.21 
0.43 
0.53 
__________________________________________________________________________ 
EXAMPLE 3. 
98.0 grams of mixed light rare earth metals was dissolved in 100 ml of 
nitric acid to form a solution. 84.65 grams of strontium nitrate, 238.7 
grams of iron nitrate, 35.79 grams of manganese nitrate and 37.51 grams of 
copper nitrate were dissolved in water to form a solution. Thereafter, the 
above two solutions are mixed together to form 2000 ml of a mixed 
solution. The resulting mixed solution is charged into the coating tank 
(23) of the fast coating apparatus. 4 kg of catalyst with the 
stoichiometric formula [RE.sub.0.6 Sr.sub.0.4 ][Fe.sub.0.6 Mn.sub.0.2 
Cu.sub.0.2 O.sub.3 as catalytic material was obtained by using the method 
as described in Example 2. 
The catalyst as prepared above was used to purify automobile waste gases 
and showed noise suppression effects. By experiment, this catalyst was 
shown to have a useful life exceeding a vehicle travelling distance of 
58,000 km. The comparison data between an automobile waste gas purifier 
(HF-type) using the catalyst of the present invention and an ordinary 
muffler are shown in Tables 3 and 4. 
TABLE 3 
__________________________________________________________________________ 
Results of Plateform Test In A BJ-492 Engine* 
Engine Speed (km/hr) 
idle 
20 30 40 50 60 70 average 
__________________________________________________________________________ 
effective 
engine + hollow pipe 
-- 4.12 
6.77 
10.41 
15.21 
20.8 
28.78 
14.36 
power (hp) 
engine + muffler 
-- 4.14 
6.76 
10.42 
15.08 
21.08 
28.50 
14.33 
engine + purifier 
0.30 
4.08 
6.79 
10.38 
14.87 
21.54 
28.47 
14.35 
gas flow 
muffler 12.0 
17.5 
21.5 
33.52 
68.0 
104.0 
186.0 
63.2 
resistance 
purifier 25 4.0 
10.5 
14.5 
32.5 
63.0 
110.0 
33.9 
(mmH.sub.2 O) 
specific 
engine + hollow pipe 
-- 436 
368 
314 
288 
278 
287 
328 
fuel con- 
engine + muffler 
-- 433 
376 
316 
286 
278 
284 
329 
sumption 
engine + purifier 
3866 
428 
370 
309 
295 
278 
284 
327 
(g/hp.hr) 
concern- 
front of purifier 
5.05 
3.5 
4.3 
1.7 
1.7 
2.4 
2.3 
3.0 
tration 
back of purifier 
0.47 
0.05 
1.8 
0.05 
0.5 
1.1 
1.8 
0.8 
of CO in 
exhaust (%) 
concern- 
front of purifier 
6850 
1100 
350 
205 
200 
180 
200 
1298 
tration 
back of purifier 
1160 
0 150 
50 100 
100 
100 
237 
of HC in 
exhaust 
(ppm) 
concern- 
front of purifier 
47.2 
431 
119 
88 117 
115 
85 143 
tration 
back of purifier 
6.6 
168 
95 40 93 69 96 81 
of NO.sub.x in 
exhaust 
(mg/m.sup.3) 
noise engine + hollow pipe 
113 
114 
117 
123 
126 
131 
136 
123 
dB(A) engine + muffler 
66 70 72 78 82 88 89 78 
engine + purifier 
62 65 68 70 74 80 82 76 
__________________________________________________________________________ 
*HF-Type of purifier contains 1.7 l of catalyst having ABO.sub.3 -type, 
fuel is a lead containing gasoline. 
TABLE 4 
__________________________________________________________________________ 
Comparison of Automobile Waste Gas Purifier (HF-Type) (N) 
using the catalyst of the present invention and origional muffler (M) 
Purification of 
Purification of Times to accelerate 
Fuel consumption 
CO at idle speed 
HC at idle speed engine in sec reduction 
concentra- 
efficiency 
concentra- 
efficiency 
Noise level 
25/60 
15/40 
fuel 
of fuel- 
Auto tion (%) 
of purifi- 
tion (ppm) 
of purifi- 
dB(A) (km/hr) 
(km/hr) 
tion 1/100 
consump- 
mobiles 
Purifier 
M/N cation (%) 
M/N cation (%) 
M/N M/N M/N M/N tion 
__________________________________________________________________________ 
(%) 
BJ-130 
HF-1 6.8/0.9 
86.8 1626/100 
93.8 81.3/79.4 
20.9/19.7 
28.4/28.3 
-- -- 
(light 
truck) 
BJ-212 
HF-1 2.4/0.28 
90.4 2000/145 
92.8 79.3/80.0 
13.1/11.6 
12.2/16.1 
10.3/9.55 
7.3 
(Jeep) 
TJSF HF-1 6.2/0.13 
97.9 1000/ 86.2 76.7/76.2 
23.3/23.1 
28.4/28.6 
-- -- 
travel- 
ling car 
WU HAN 
HF-1 5.94/0.02 
99.0 4000/115 
97.1 79.8/77.3 
17.1/17.1 
21.1/20.4 
13.3/12.1 
9.0 
121 
(Jeep) 
WU HAN 
HF-2 5.4/1.0 
81.5 2300/450 
80.4 85.8/84.6 
-- -- -- -- 
121 
(Jeep) 
Jie Fang 
HF-3 0.22/0.06 
72.7 530/20 
86.8 90.0/84.5 
19.8/19.5 
30.2/31.1 
-- -- 
CA-10C 
(truck) 
CA-653 
HF-4 4.22/0.05 
98.7 1020/955 
90.6 88.4/79.8 
43.6/39.6 
57.8/52.2 
29.5/28.4 
3.7 
(sedan) 
__________________________________________________________________________ 
EXAMPLE 4. 
454.90 grams of lanthanum nitrate, 63.49 grams of strontium nitrate, 49.22 
grams of calcium nitrate, 242.27 grams of iron nitrate and 73.08 grams of 
nickel nitrate are dissolved in water to form 2500 ml of solution. The 
resulting solution is charged into the coating tank (23) of the coating 
apparatus. 5 kg of catalysts with the following stiochiometric formula 
[La.sub.1.4 Sr.sub.0.3 Ca.sub.0.3 ][Fe.sub.0.6 Ni.sub.0.4 ]O.sub.4 as the 
catalytic material was obtained using the same method and conditions as 
described in Example 2 except that the oxidizing temperature was from 
800.degree. C. to 850.degree. C. 
When this catalyst was used in the purification of waste gas containing 100 
ppm of NO.sub.x, at a space velocity of 10000 h.sup.-1 and a temperature 
of 300.degree. C. After purification the gas contained less than 0.6 ppm 
of NO.sub.x. 
The above-mentioed catalysts may also be formed into various shapes and 
sizes as desired. The overall characteristics of the catalysts of the 
present invention is shown in Table 5. 
TABLE 5 
______________________________________ 
Shape Of Catalyst 
industrial waste 
automobile waste 
characteristic 
unit gases gases 
______________________________________ 
external mm 200 .times. 200 .times. 50 
.phi. 120 .times. 25 
size 250 .times. 200 .times. 50 
.phi. 150 .times. 25 
hole surface 
mm.sup.2 
2.7 2.3 
area 
hole wall mm 0.05-0.12 0.05-0.12 
thickness 
free % 88-92 85-88 
section surface 
specific weight 
kg/l 0.5-0.6 0.75-0.85 
parts by weight 
% 7-8 7-8 
of catalytic 
material in 
the catalyst 
______________________________________ 
The catalysts prepared by the method according to the invention can be 
regenerated. Regeneration test results are shown in Table 6. The test 
results show that the catalysts can be regenerated by different methods 
according to the cause of reduction of catalytic activity. When the 
catalysts becomes completely inactive, the supports may be re-used. 
TABLE 6 
__________________________________________________________________________ 
Results of Regeneration Test 
Activity 
Initial Before 
Efficiency 
Regeneration 
After 
Cause of Activity 
Catalysts 
Regeneration 
Activity 
Method of 
t 50% 
t 90% 
t 50% 
t 90% 
t 50% 
t 90% 
Reduction 
Regeneration 
(.degree.C.) 
(.degree.C.) 
(.degree.C.) 
(.degree.C.) 
(.degree.C.) 
(.degree.C.) 
__________________________________________________________________________ 
dust washing with 
214 365 260 477 216 260 
pollution 
1% of wash 
liquid, and 
then drying 
heated at 
reactivating 
190 420 342 590 190 410 
700.degree. C. for 
with gas 
2 hours 
flow at 450.degree. C. 
for 2 hours 
heating 290 393 370 560 370 560 
in Presence 
of air at 500.degree. C. 
for 2 hours 
carbon heating 290 393 370 560 300 398 
deposit 
in presence 
of air at 500.degree. C. 
for 24 hours 
heating 270 420 290 441 270 421 
in presence 
of air at 650.degree. C. 
for 2 hours 
Loss of 
wash with 
224 350 432 605 216 350 
catalytic 
1% of wash 
material 
liquid, 
dry, and 
coat with 
catalytic 
material 
according to 
original 
composition 
__________________________________________________________________________