Removal of nitric oxides by copper-containing zeolites

Copper-containing zeolites are prepared by subjecting a zeolite having the lattice spacings (d value) indicated in Table 1 as estimated by powder X-ray diffraction to ion exchange with copper ions in an aqueous solution containing a water soluble copper salt and ammonia. Nitrogen oxides can be decomposed with the copper-containing zeolite catalyst.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to the production of catalysts and adsorbents 
which can be used for the removal of nitrogen oxides from exhaust gases 
containing the same. 
2. Description of the Background 
Nitrogen oxides (hereinafter referred to as NO.sub.x) are found in 
combustion exhaust gases from industrial plants and automobiles and lead 
to the production of photochemical smog. Methods to prevent the formation 
of such smog are urgently needed for environmental safety. 
At present, both dry and wet methods are known for the removal of NO.sub.x. 
Using wet methods, the NO.sub.x is contained in exhaust liquids which are 
quite difficult to treat. Therefore, the wet methods are still not of 
practical use. Among the dry methods, there are known methods such as 
non-catalytic reduction, direct catalytic decomposition, selective 
catalytic reduction, and adsorption. Among these methods, the selective 
NH.sub.3 catalytic reduction method is already in practical use. However, 
this process requires NH.sub.3 as a reducing agent, and further requires 
devices for the recovery or decomposition of unreacted NH.sub.3, thus 
leading to a more complicated process. 
The direct catalytic decomposition of NO.sub.x is the most preferred 
method, since it entails the simplest process and does not require a 
reducing agent such as NH.sub.3. Hitherto, a number of investigations have 
been performed on the direct catalytic decomposition of NO.sub.x. Pt, CuO 
and Co.sub.3 O.sub.4 are known to exhibit catalytic activity in 
decomposing NO.sub.x, but the activity remains insufficient due to the 
poisoning action of the decomposition product oxygen. Thus, these 
catalysts cannot be used in practice. 
Recently, the zeolite (ZSM-5) which contains copper ions and has a specific 
crystalline structure has been found to act as a decomposition catalyst 
for NO (Japanese Laid-Open Patent Application No. Sho 60-125250) in the 
direct catalytic decomposition of NO.sub.x which does not suffer from the 
poisoning action of moisture and oxygen even if they are present in the 
gas to be treated. The ZSM-5 containing copper as disclosed in the cited 
reference is prepared from conventional ZSM-5 by subjecting the same to 
ion exchange in an aqueous solution of a water-soluble divalent copper 
salt. 
There are a large number of reports regarding ZSM5 containing copper. In 
Japanese Laid-Open Patent Application No. Sho 54-96500, for example, the 
ZSM-5 containing copper is prepared from ZSM-5 by repeated ion exchange 
with an aqueous solution of a watersoluble divalent copper salt. The 
product is used as a catalytic combustion catalyst. 
In Japanese Laid-Open Patent Application No. Sho 57-36015 and U.S. Pat. No. 
4,297,328, the ZSM-5 is ion exchanged three times with an aqueous solution 
of copper(II) chloride at a refluxing temperature to obtain a rate of 
exchanged copper ions of larger than 160%. The prepared materials are used 
as a combustion catalyst and as ternary catalyst, respectively. 
However, as long as the conventional ion exchange method is employed, the 
exchange of a large amount of copper is not possible in a single run, 
instead, several repeated runs of exchange are needed. 
ZSM-5 containing copper which evidences activity in the direct catalytic 
decomposition reaction of NO can be prepared by the process described in 
the existing literature. However, the ion exchange carried out as 
described in the literature does not yield a sufficient amount of copper 
ions in a single run and repeated runs are necessary. Therefore, several 
repeated procedures of ion exchange are needed to obtain a larger amount 
of exchanged copper and to attain a high activity for the decomposition of 
NO. 
Thus, a need continues to exist for a process by which nitrogen oxides in 
exhaust gases can be catalytically decomposed in an efficacious manner. A 
need also continues to exist for a process by which a catalyst having the 
above-described properties can be prepared in high yield. 
SUMMARY OF THE INVENTION 
Accordingly, it is an object of this invention to provide a process for the 
production of a copper-containing zeolite catalyst which is advantageously 
used in the decomposition of nitrogen oxides in gases containing the same. 
Further, it is an object of this invention to provide a process for the 
catalytic decomposition of nitrogen oxides. 
These objects and others which will become more apparent in view of the 
following disclosure are provided, in particular, by a copper-containing 
zeolite which is produced by subjecting a zeolite having the following 
lattice spacings (d values) as determined by powder X-ray diffraction to 
ion exchange with copper ions in an aqueous solution containing a 
water-soluble copper salt and ammonia. 
______________________________________ 
lattice spacing 
relative lattice spacing 
relative 
(d value) strength (d value) strength 
______________________________________ 
11.1 .+-. 0.3 
strong 4.60 .+-. 0.08 
weak 
10.0 .+-. 0.3 
strong 4.25 .+-. 0.08 
weak 
7.4 .+-. 0.2 
weak 3.85 .+-. 0.07 
very strong 
7.1 .+-. 0.2 
weak 3.71 .+-. 0.05 
strong 
6.3 .+-. 0.2 
weak 3.04 .+-. 0.03 
weak 
6.04 .+-. 0.2 
weak 2.99 .+-. 0.02 
weak 
5.56 .+-. 0.1 
weak 2.94 .+-. 0.02 
weak 
5.01 .+-. 0.1 
weak 
______________________________________

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The present invention relates to the production of catalysts which are used 
to remove nitrogen oxides from gases containing the same which are 
released from industrial plants and automobiles, for example. Also, this 
invention provides a process for producing catalysts for the direct 
catalytic decomposition of NO.sub.x as well as a method of use therefor. 
The catalyst of the present invention is prepared from a basic material 
zeolite having the following lattice spacings (d values) as shown in Table 
1. The basic material zeolite may be prepared by any known method without 
restriction. 
TABLE 1 
______________________________________ 
Lattice Lattice 
spacing Relative spacing Relative 
(d value) strength (d value) strength 
______________________________________ 
11.1 .+-. 0.3 
strong 4.60 .+-. 0.08 
weak 
10.0 .+-. 0.3 
strong 4.25 .+-. 0.08 
weak 
7.4 .+-. 0.2 
weak 3.85 .+-. 0.07 
very strong 
7.1 .+-. 0.2 
weak 3.71 .+-. 0.05 
strong 
6.3 .+-. 0.2 
weak 3.04 .+-. 0.03 
weak 
6.04 .+-. 0.2 
weak 2.99 .+-. 0.02 
weak 
5.56 .+-. 0.1 
weak 2.94 .+-. 0.02 
weak 
5.01 .+-. 0.1 
weak 
______________________________________ 
Preferably, the ratio in moles of SiO.sub.2 to Al.sub.2 O.sub.3 of the 
zeolite to be used in this invention is 15 to 300, more preferably 20 to 
200. The basic material zeolite having the lattice spacings (d values) as 
indicated in Table 1 has almost no activity in decomposing NO.sub.x, if it 
is used without further treatment. 
The copper-containing zeolite of the present invention can be prepared from 
the zeolite having the lattice spacings (d values) as indicated in Table 1 
either by exchanging cations in the zeolite with copper ions in an aqueous 
solution containing a water-soluble copper salt and ammonia, or by 
supplying ammonia gas to be adsorbed on zeolites on which cations have 
been exchanged with copper ions. 
Any copper salt may be used so long as it is a water-soluble salt. Salts 
applicable are, for example, the sulfate, chloride, acetate, nitrate and 
other salts of copper. Ammonia may be applied in the form of ammonia 
water, hydrous ammonia compounds, and aqueous solutions containing 
dissolved ammonia. The ammonia may be added in any amount, but preferably 
in such a amount that the pH of a slurry containing the zeolite is in the 
range from 4 to 12. When the pH is less than 4, the exchange of ions 
hardly occurs because of the low speed of ion exchange. When the pH 
exceeds 12, impure copper is deposited and therefore the activity of the 
catalyst in decomposing NO.sub.x is lowered. The concentration of copper 
ions in the aqueous solution may be set as needed according to the 
required rate of exchanged copper ions of the zeolite. 
The copper ions in the form of Cu.sup.+, Cu.sup.2+, CuOH.sup.+, and 
[Cu(NH.sub.3).sub.4 ].sup.2+ exchange with cations on the zeolite. A part 
of the zeolite is also turned into the NH.sub.4 -type due to the presence 
of a large excess of NH.sub.3 molecules. 
In the above method of preparation, a rate of exchanged copper ions greater 
than 100% and a NH.sub.3 content of more than 0.2 molecule per unit Cu 
atom can be achieved with the product obtained by a single exchange 
procedure. 
The product produced by ion exchange is washed with water and dried, to 
obtain the present coppercontaining zeolite catalyst. 
The copper content of the copper-containing zeolite is preferably larger 
than 0.03%, more preferably larger than 1% by weight. In general, the 
larger the copper content of the copper-containing zeolite is, the greater 
is the decomposition activity for NO.sub.x. 
The present copper-containing zeolite catalysts also exhibit high 
activities as a reductive denitration catalyst for NO.sub.x. 
The ratio in moles of SiO.sub.2 to Al.sub.2 O.sub.3 of copper-containing 
zeolite is substantially the same as that of the original zeolite. Also 
the crystalline structure of the copper-containing zeolite remains 
unchanged through the ion exchange treatment and therefore can be 
characterized by the lattice spacings (d values) indicated in Table 1. 
The NH.sub.3 content of the copper-containing zeolite catalyst was 
determined by the neutralization titration for the analysis of ammonia 
("Handbook for Analytical Chemistry", 1971, Maruzen, Tokyo). The procedure 
used is as follows. First, a solution of NaOH is added to a sample of the 
catalyst, then NH.sub.3 is liberated by distillation and absorbed in a 
known excess of a standard solution of acid where the excess of acid is 
determined by back titration with a standard solution of NaOH. 
At present, it is not clear why the copper-containing zeolites prepared 
according to the present invention exhibit such a high activity in the 
catalytic decomposition of NO.sub.x, however it is thought that the 
ammonia molecules captured on the zeolite together with copper ions are 
liberated in the pretreatment stage of the catalytic decomposition 
reaction of NO.sub.x, and partially reduce the Cu.sup.2+ into Cu.sup.+ 
which forms an active site for the catalytic decomposition reaction of 
NO.sub.x. The facility of the oxidation-reduction process, Cu.sup.+ 
.revreaction.Cu.sup.2+, is perhaps decisive in maintaining the high 
activity. 
Japanese Laid-Open Patent Application Nos. Sho 54-96500 and Sho 57-36015 
disclose that copper, after ion exchange treatment, exists in the form of 
CuOH.sup.+ and can be changed to Cu.sup.+ at temperatures approximately 
above 300.degree. C. However, the copper-containing ZSM-5 prepared 
according to the method of these references exhibit a much lower activity 
for decompositing NO.sub.x than the copper-containing zeolite catalysts of 
the present invention. 
The copper-containing zeolite catalysts of the present invention may have a 
higher activity due to the presence of Cu.sup.+ which is formed when the 
ammonia molecules coordinating to copper ions are liberated in the 
pretreatment stage. This Cu.sup.+ may be considered to be different in 
the degree of reduction from the Cu.sup.+ formed via CuOH.sup.+, thus 
leading to the difference in the activity for decomposing NO.sub.x. 
In short, the copper-containing zeolite catalysts prepared by the method of 
the present invention having a specific crystalline structure are highly 
active even at low temperatures as a result of the compound effect of 
structural stability and thermal resistance. The present catalysts are, 
moreover, free from the influence of oxygen and moisture, and are also 
stationarily stable. 
In the decomposition reaction using the copper-containing zeolite 
catalysts, time of contact of the gases to be treated with the catalysts 
is not particularly restricted. In accordance with the components and the 
concentration of gas to be treated, the best ratio values for moles of 
SiO.sub.2 to Al.sub.2 O.sub.3 and the rate of exchanged copper ions can be 
selected. In the combined use of these factors, the temperature of the 
reaction and time of contact of the gas with the catalyst can be set so 
that the decomposition activity together with other characteristics of the 
catalyst can be exhibited to the highest degree. 
The temperature at which the copper-containing zeolite catalysts are used 
as a decomposition catalyst for NO.sub.x is in the range from 200.degree. 
to 1,000.degree. C., preferably from 300.degree. to 700.degree. C. 
The copper-containing zeolite catalysts prepared in the present invention 
can be used as a catalyst and also as an adsorbent in petroleum chemistry, 
the purification of petroleum and the prevention of environmental 
pollution. Among the above applications, these catalysts particularly 
exhibit excellent activity in decomposing NO.sub.x, when they are used as 
a catalyst for decomposing and removing NO.sub.x from a gas containing the 
same. 
The copper-containing zeolite catalysts of the present invention may also 
be supplied in the form of moldings which are shaped using such binders as 
clay minerals. 
In another aspect of this invention, a zeolite molding which is shaped 
beforehand is submitted to exchange with copper ions in an aqueous 
solution containing a water-soluble copper salt and ammonia. The 
dimensions of the moldings are not particularly restricted. 
The zeolite moldings as the basic material of the catalysts of this 
invention are required to exhibit the lattice spacings (d values) 
indicated in Table 1, but may be prepared by any known method without 
restriction. The zeolites are granulated using clay as a binder. For 
example, kaolin, attapulgite, montmorillonite, bentonite, allophane, and 
sepiolite may be used. Five to thirty parts of these binders are used to 
100 parts of zeolite. Otherwise, moldings called binderless moldings, may 
be prepared directly from the zeolite, itself, without using any binder. 
The present invention will now be further illustrated by reference to the 
following Examples which are provided solely for the purpose of 
illustration and are not intended to be limitative. 
EXAMPLE 1 
(Synthesis of zeolite) 
Into an overflow type reaction tank of a 2 liter net capacity which is 
under agitation, aqueous solutions of sodium silicate (SiO.sub.2 ; 153.4 
g/l, Na.sub.2 O; 49.9 g/l, Al.sub.2 O.sub.3 ; 0.8 g/l) and aluminum 
sulfate together with sulfuric acid (Al.sub.2 O.sub.3 ; 38.4 g/l, H.sub.2 
SO.sub.4 ; 275.4 g/l) were supplied continuously at a speed of 3.2 l/hr 
and 0.1 l/hr, respectively. The temperature of the reaction was 30.degree. 
to 32.degree. C. and the pH of the slurry was 6.4 to 6.6. Solid matter was 
separated with a centrifuge from the slurry produced, thoroughly washed 
with water, to obtain a homogeneous and amorphous aluminosilicate compound 
in fine particles (Na.sub.2 O; 1.72 wt %, Al.sub.2 O.sub.3 ; 2.58 wt %, 
SiO.sub.2 ; 39.3 wt %, H.sub.2 O; 56.4 wt %). This homogeneous compound 
(2840 g) and an aqueous solution of NaOH (1.39 wt %, 5160 g) were placed 
in an autoclave of a 10 liter capacity and the solid matter was allowed to 
be crystallized at 160.degree. C. under agitation for 72 hrs. The product 
obtained was separated, washed with water and dried, to obtain zeolite 
TSZ-821 which is used as a basic material for preparing the 
copper-containing zeolite catalyst. Chemical analysis revealed the 
composition to have a molar ratio of oxides on an anhydride basis: 
EQU 1.05 Na.sub.2 O.Al.sub.2 O.sub.3.23.3 SiO.sub.2 
In addition, d values estimated by powder X-ray diffraction patterns were 
essentially identical with those indicated in Table 1. 
Next, using the same procedure as that for the synthesis of TSZ-821, fine 
particles of homogeneous amorphous compounds of aluminosilicate of 
different SiO.sub.2 and Al.sub.2 O.sub.3 content were prepared, allowed to 
crystallize by heating in an aqueous solution of sodium hydroxide under 
agitation, to obtain zeolites TSZ-841 and TSZ-851 which are basic 
materials for the preparation of the copper-containing zeolite catalysts. 
These may be represented by the following formulae in molar ratios of 
oxides on an anhydride basis: 
EQU TSZ-841: 1.41 Na.sub.2 O.Al.sub.2 O.sub.3.40.4 SiO.sub.2 
EQU TSZ-851: 1.05 Na.sub.2 O.Al.sub.2 O.sub.3.49.0 SiO.sub.2 
The d values of these zeolites determined by the powder X-ray diffraction 
patterns were essentially identical with those in Table 1. 
EXAMPLE 2 
(Preparation of copper-containing zeolite) 
TSZ-821 obtained in Example 1 was taken in an amount of 10 g, mixed with a 
0.1 mol/l aqueous solution of copper acetate so as to make the number of 
copper atoms equal to the number of Al atoms in the zeolite. The mixture 
was stirred at room temperature, mixed with a 2.5% aqueous NH.sub.3 
solution, to make the pH of the slurry 6.0. Then, the slurry was agitated 
for 12 hrs. at room temperature. The solid matter was separated, 
thoroughly washed with water, dried at 100.degree. C. for 10 hrs. The 
copper-containing zeolite catalyst thus obtained was designated as 
TSZ-821-A. The rate of exchanged copper ions of the copper-containing 
zeolite catalyst as determined by chemical analysis is indicated in Table 
2, where divalent copper was assumed to indicate the rate of exchanged 
copper ions. In addition, ammonia existing in the copper-containing 
zeolite catalyst was determined by the neutralization titration, of which 
result expressed in moles per unit atom of Cu is also found in Table 2. 
TABLE 2 
______________________________________ 
Copper- Rate of Cu 
containing 
exchanged content NH.sub.3 
zeolite copper (%) (wt %) (NH.sub.2 /Cu) 
______________________________________ 
TSZ-821-A 124 6.37 0.51 
______________________________________ 
EXAMPLE 3 
(Preparation of copper-containing zeolite catalyst) 
The TSZ-821 obtained in Example 1 was taken in the amount of 10 g and an 
aqueous 0.1 mol/l solution of copper acetate was added so that the number 
of copper atoms is 0.34 times as many as that of Al atoms in the zeolite. 
The mixture was stirred at room temperature and mixed with a 2.5% aqueous 
solution of NH.sub.3 to afford a pH of 10.5 in the resulting slurry. Then 
agitation was continued at room temperature until the required rate of 
exchanged copper ions is attained in the zeolite. Solid matter formed was 
separated, thoroughly washed with water, and dried at 100.degree. C. for 
10 hrs. The copper-containing zeolite obtained was named TSZ-821-B. The 
rate of exchanged copper ions of the copper-containing zeolite catalyst as 
determined by chemical analysis is shown in Table 3. Divalent copper was 
assumed on the exchange in determining the rate of exchanged copper ions. 
Ammonia existing in the copper-containing zeolite catalyst was determined 
by the neutralization titration, of which result expressed in moles per 
unit atom of Cu is also found in Table 3. 
EXAMPLE 4 
(Preparation of copper-containing zeolite catalyst) 
The TSZ-821, TSZ-841 and TSZ-851 obtained in Example 1 were taken each in 
the amount of 10 g and an aqueous 0.1 mol/l solution of copper acetate was 
added to each so that the number of copper atoms are equal to that of Al 
atoms in each zeolite. The mixtures were stirred at room temperature and 
mixed with a 2.5% aqueous solution of NH.sub.3 to afford a pH of 10.5 in 
the resulting slurry. Then agitation was continued at room temperature 
until the required rate of exchanged copper ions was attained in the 
zeolite. Solid matter was separated, thoroughly washed with water, and 
dried at 100.degree. C. for 10 hrs. The copper-containing zeolites 
obtained were named TSZ-821-C, TSZ-841-D, and TSZ-851-E, respectively. The 
rates of exchanged copper ions of the copper-containing zeolites 
determined by chemical analysis are shown in Table 3. Divalent copper was 
assumed on exchange in determining the rate of exchanged copper ions. 
Ammonia existing in the copper-containing zeolite catalysts was determined 
by the neutralization titration, of which result expressed in moles per 
unit atom of Cu is also found in Table 3. 
TABLE 3 
______________________________________ 
Copper- Rate of Cu 
containing 
exchanged content NH.sub.3 
zeolite copper (%) (wt %) (NH.sub.3 /Cu) 
______________________________________ 
TSZ-821-B 66 3.43 0.82 
TSZ-821-C 123 6.12 0.83 
TSZ-841-D 121 3.61 0.78 
TSZ-851-E 127 3.29 0.69 
______________________________________ 
EXAMPLE 5 
(Test of the decomposition activity for NO of copper-containing zeolite 
catalyst) 
The copper-containing zeolite catalysts prepared in Examples 2, 3 and 4 
were press-molded and broken into uniform particles of 42 to 80 mesh. A 
normal pressure flow-type fixed bed reaction tube was packed with 1 g of 
each catalyst. Prior to the reaction, the copper-containing zeolite 
catalysts were pretreated by elevating the temperature to 500.degree. C. 
at a speed of 5.degree. C./min in a stream of helium and maintaining the 
temperature for 2 hrs. Helium gas which contained NO in a concentration of 
5000 ppm was forced to flow through the packing layer of the 
copper-containing zeolite catalysts at a flow rate of 15 cc/min to allow 
reaction. In 50 min of reaction at selected temperatures, the rate of 
conversion of NO was determined. Results are shown in Table 4. 
TABLE 4 
______________________________________ 
Copper-containing zeolite 
TSZ- TSZ- TSZ- TSZ- TSZ- 
821-A 821-B 821-C 841-D 851-E 
Rate of Rate of Rate of Rate of 
Rate of 
conver- conver- conver- conver- 
conver- 
sion of sion of sion of sion of 
sion of 
NO (%) NO (%) NO (%) NO (%) NO (%) 
______________________________________ 
400 97.3 94.0 97.2 94.1 95.8 
500 100 100 100 100 80.5 
600 100 100 100 100 60.3 
______________________________________ 
EXAMPLE 6 
(Stability of activity of the copper-containing zeolite catalyst) 
Sustaining ability of the copper-containing zeolite catalyst TSZ-821-C 
(rate of exchanged copper ions of 123%) to decompose NO was determined. 
The same apparatus and the same method as in Example 5 were employed and 
the temperature for reaction 500.degree. C. was selected. Time variation 
of the rate of conversion is shown in FIG. 1. 
COMISON EXAMPLE 1 
(Preparation of zeolite for comparison) 
The TSZ-821 obtained in Example 1 was taken in the amount of 10 g, mixed 
with an aqueous 0.1 mol/l solution of copper acetate so that number of 
copper atoms is equal to that of Al atoms on the zeolite, and stirred for 
12 hrs. at room temperature. Solid matter was separated from the slurry, 
washed with water and dried at 100.degree. C. for 10 hrs. The obtained 
zeolite for comparison was named TSZ-821-F. The rates of exchanged copper 
ions on the catalysts for comparison which was determined by chemical 
analysis is shown in Table 5. 
COMISON EXAMPLE 2 
(Preparation of zeolite for comparison) 
The TSZ-821 obtained in Example 1 was taken in the amount of 10 g, mixed 
with an aqueous 0.1 mol/l solution of copper acetate so that number of 
copper atoms is equal to that of Al atoms in the zeolite, and stirred for 
12 hrs. at room temperature. Solid matter was separated from the slurry 
and washed with water. After repeating the procedure two times, the solid 
was dried at 100.degree. C. for 10 hrs. 
The obtained zeolite for comparison was named TSZ-821-G. The rate of 
exchanged copper ions on the catalysts for comparison, determined by 
chemical analysis, is found in Table 5. 
COMISON EXAMPLE 3 
(Preparation of zeolite for comparison) 
The TSZ-821 obtained in Example 1 was taken in the amount of 10 g, mixed 
with an aqueous 0.1 mol/l solution of copper(II) chloride so that number 
of copper atoms is equal to that of Al atoms in the zeolite, and stirred 
for 12 hrs. at room temperature. Solid matter was separated from the 
slurry, washed with water and dried at 100.degree. C. for 10 hrs. The 
obtained zeolite for comparison was named TSZ-821-H. The rates of 
exchanged copper ions on the catalyst for comparison determined by 
chemical analysis is shown in Table 5. 
COMISON EXAMPLE 4 
(Preparation of zeolite for comparison) 
The TSZ-821 obtained in Example 1 was taken in the amount of 10 g, mixed 
with an aqueous 0.1 mol/l solution of copper(II) chloride so that number 
of copper atoms is equal to that of Al atoms on the zeolite, and stirred 
for 12 hrs. at room temperature. Solid matter was separated from the 
slurry and washed with water. After additional 2 time repetition of the 
procedure, the solid was dried at 100.degree. C. for 10 hrs. 
The obtained zeolite for comparison was named TSZ821-I. The rate of 
exchanged copper ions on the catalysts for comparison, determined by 
chemical analysis, is also found in Table 5. 
TABLE 5 
______________________________________ 
Zeolite for Rate of exchanged 
Copper content 
comparison copper ion (%) 
(wt %) 
______________________________________ 
TSZ-821-F 88 4.43 
TSZ-821-G 103 5.26 
TSZ-821-H 88 4.50 
TSZ-821-I 104 5.33 
______________________________________ 
COMISON EXAMPLE 5 
(Test of activity for decomposing NO of zeolite for comparison) 
The rate of conversion of NO was determined according to the method in 
Example 5 with the zeolites for comparison prepared in Comparison Examples 
1, 2, 3 and 4. Results are shown in Table 6. 
TABLE 6 
______________________________________ 
Zeolite for comparison 
TSZ- TSZ- TSZ- TSZ- 
821-F 821-G 821-H 821-I 
Rate of 
Rate of Rate of Rate of 
conver- 
conver- conver- conver- 
sion of 
sion of sion of sion of 
NO (%) NO (%) NO (%) NO (%) 
______________________________________ 
400 60.0 70.0 61.5 65.0 
500 55.2 67.5 58.0 59.8 
600 38.8 52.3 39.0 47.0 
______________________________________ 
COMISON EXAMPLE 6 
(Preparation of zeolite for comparison) 
The TSZ-821, TSZ-841 and TSZ-851 obtained in Example 1 were taken in the 
amount of 10 g each, mixed with an aqueous 0.1 mol/l solution of copper 
acetate so that number of copper atoms is equal to that of Al atoms on the 
zeolites, and stirred for 12 hrs. at room temperature. Solid matter was 
separated from the slurry and washed with water. This procedure was 
repeated 3 times and the product was dried at 100.degree. C. for 10 hrs. 
The obtained zeolites for comparison were named TSZ-821-J, TSZ-841-K and 
TSZ-851-L, respectively. The rates of exchanged copper ions on the 
catalysts for comparison which were determined by chemical analysis are 
shown in Table 7. 
TABLE 7 
______________________________________ 
Zeolite for Rate of exchanged 
Copper content 
comparison copper ion (%) 
(wt %) 
______________________________________ 
TSZ-821-J 112 5.67 
TSZ-841-K 108 3.31 
TSZ-851-L 118 3.16 
______________________________________ 
COMISON EXAMPLE 7 
(Test of activity for decomposing NO of zeolites for comparison) 
The rate of conversion of NO was estimated with the zeolites for comparison 
prepared in Comparison Example 6, according to the method in Example 5. 
Results are found in Table 8. 
TABLE 8 
______________________________________ 
Zeolite for comparison 
TSZ- TSZ- TSZ- 
821-J 841-K 851-L 
Rate of Rate of Rate of 
conver- conver- conver- 
sion of sion of sion of 
NO (%) NO (%) NO (%) 
______________________________________ 
400 70.8 37.9 31.0 
500 69.0 39.3 27.0 
600 54.9 28.8 17.0 
______________________________________ 
COMISON EXAMPLE 8 
(Preparation of zeolite for comparison) 
The TSZ-821 obtained in Example 1 was taken in the amount of 10 g, mixed 
with an aqueous 0.10 mol/l solution of copper(II) chloride. The mixture 
was stirred for 3 hrs. at a refluxing temperature. Solid matter was 
separated and washed. After repeating the procedure three times, the 
product was dried at 100.degree. C. for 10 hrs. The zeolite for comparison 
thus obtained was named TSZ-821-M. The rate of exchanged copper ions as 
determined by chemical analysis is shown in Table 9. 
TABLE 9 
______________________________________ 
Zeolite for Rate of exchanged 
Copper content 
comparison copper ion (%) 
(wt %) 
______________________________________ 
TSZ-821-M 167 6.38 
______________________________________ 
COMISON EXAMPLE 9 
(Test of activity of decomposing NO of zeolite for comparison) 
The rate of conversion of NO was estimated by the method described in 
Example 5 with the zeolite for comparison prepared in Comparison Example 
8. Results are shown in Table 10. 
TABLE 10 
______________________________________ 
Zeolite for comparison 
TSZ-821-M 
Rate of conversion 
of NO 
______________________________________ 
400 76.8 
500 70.5 
600 62.0 
______________________________________ 
EXAMPLE 7 
(Production of zeolite molding) 
With 100 parts of zeolite prepared in Example 1, 20 parts of bole clay was 
mixed and thoroughly kneaded with a kneader. The starting mixture thus 
prepared was formed in cylinders of 1.5 mm diameter with an extrusion 
molder and the cylindrical moldings were dried at 100.degree. C. for 10 
hrs. Baking the above products at 650.degree. C. for 1 hr gave zeolite 
moldings. Their chemical composition can be expressed by molar ratios of 
oxides on an anhydride basis as follows: 
EQU TSZ-821 molding: 0.78 Na.sub.2 O.Al.sub.2 O.sub.3.16.4 SiO.sub.2 
The d values of the TSZ-821 molding as determined by the powder X-ray 
diffraction pattern were essentially identical with those in Table 1. 
EXAMPLE 8 
(Preparation of copper-containing zeolite molding) 
The molding of TSZ-821 produced in Example 7 was taken in the amount of 10 
g and immersed in an aqueous 0.1 mol/l solution of copper acetate so that 
the number of copper atoms is equal to that of Al atoms on the zeolite. 
The mixture was stirred at room temperature, and mixed with an aqueous 
2.5% solution of NH.sub.3 so as to make the pH of the slurry 10.5. 
Then stirring continued at room temperature for 12 hrs. Solid matter was 
separated, thoroughly washed with water, and dried at 100.degree. C. for 
10 hr. The copper ion content of the copper-containing zeolite molding 
(designated as TSZ-821-molding-A) as determined by chemical analysis is 
shown in Table 11. 
TABLE 11 
______________________________________ 
Copper-containing 
Copper content 
zeolite molding (wt %) 
______________________________________ 
TSZ-821-molding-A 
5.17 
______________________________________ 
EXAMPLE 9 
(Test of activity for decomposing NO of the copper-containing zeolite 
molding) 
The copper-containing zeolite molding(TSZ-821-molding-A) prepared in 
Example 8 was grounded in a mortar to obtain particles of 42 to 80 mesh. 
Then a normal pressure flow-type fixed bed reaction tube was packed with 1 
g of the particles. Prior to the reaction, the copper-containing zeolite 
molding was heated up to 500.degree. C. with an elevation speed at 
5.degree. C./min and the final temperature was maintained for 2 hrs. with 
passage of helium gas. A helium gas containing 5000 ppm of NO was passed 
through the layer packed with the copper-containing zeolite molding at a 
speed of 15 cc/min to allow reaction. In 50 min of the reaction, the rate 
of conversion of NO was estimated at each temperature of reaction. Results 
are found in Table 12. 
TABLE 12 
______________________________________ 
Copper-containing 
zeolite molding TSZ-821-molding-A 
Reaction Conversion rate 
Temperature (.degree.C.) 
of NO (%) 
______________________________________ 
400 100 
500 100 
600 100 
______________________________________ 
EXAMPLE 10 
(Stability of activity of the copper-containing zeolite molding) 
The sustained ability of the present catalysts for decomposing NO was 
tested using TSZ-821-molding-A containing copper. The same apparatus and 
the same method as in Example 9 were employed and the reaction was carried 
out at 500.degree. C. Time variation of the rate of conversion is shown in 
FIG. 2. 
COMISON EXAMPLE 10 
(Preparation of zeolite for comparison) 
The TSZ-821 molding obtained in Example 7 was taken in the amount of 10 g 
and mixed with an aqueous 0.1 mol/l solution of copper(II) chloride so 
that the number of copper atoms is equal to that of Al atoms in the 
zeolite, and the mixture was stirred at room temperature. Solid matter was 
separated from the slurry and washed. After repeating the procedure three 
times, the solid was dried at 100.degree. C. for 10 hrs. Copper content of 
the zeolite for comparison (designated as TSZ-821-molding-B) obtained by 
the chemical analysis is shown in Table 13. 
TABLE 13 
______________________________________ 
Zeolite for comparison 
Copper content (wt %) 
______________________________________ 
TSZ-821-molding-B 
5.46 
______________________________________ 
COMISON EXAMPLE 11 
(Test of activity for decomposing NO for zeolite for comparison) 
The rate of conversion of NO was determined with the zeolite for comparison 
(TSZ-821-molding-B) prepared in Comparison Example 10 by the method in 
Example 9. Results are found in Table 14. 
TABLE 14 
______________________________________ 
Zeolite for comparison 
TSZ-821-molding-B 
Reaction Rate of conversion 
Temperature of NO (%) 
______________________________________ 
400 44.8 
500 21.2 
600 9.5 
______________________________________ 
Having now fully described the present invention, it will be apparent to 
one of ordinary skill in the art that many changes and modifications can 
be made to the above descriptions while remaining within the spirit and 
scope of the present invention.