JPS60212234A - Honeycomb shaped deodorizing catalyst - Google Patents

Abstract

PURPOSE:To obtain the titled catalyst receiving no deterioration in its capacity at the time of the treatment of dust-containing exhaust gas and capable of being prevented from clogging, by molding a composition containing oxide of Ti or Si and oxide of copper or Cr to form an integral structure having a large number of piercing pores. CONSTITUTION:A catalyst composition, which contains both of at least one kind of oxide of a metal selected from a group consisting of Ti, Si and Zr as a catalytic component A and at least one kind of oxide of a metal selected from a group consisting of copper, Cr, iron, V, W, Mn, Ni, Co and Mo as a catalytic component B, is molded to obtain an integral structure having a large number of piercing pores and the average diameter of said piercing pores is set to a range of 3-12mm.. In this case, the amount of the component A is adjusted to 33- 99wt% as oxide and that of the component B to 1-70wt% as oxide. This catalyst can employ a linear speed higher than that of a conventional product and is not deteriorated in its capacity due to the abrasion and release of the catalytic substances when dust-containing exhaust gas is especially treated and can be further prevented from clogging by dust.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a honeycomb type deodorizing catalyst. To be more specific, the present invention is capable of converting foul-smelling exhaust gas containing a large amount of dust, which is generated from various odor sources, into a harmless, odorless material without deteriorating performance due to abrasion or peeling of catalyst components caused by dust, and without clogging. This relates to a no-nikum type deodorizing catalyst that converts into gas and removes it.

In recent years, various types of foul-smelling exhaust gases, such as organic solvent-based foul-smelling exhaust gases generated from printing, painting, resin processing, and surface treatment factories, as well as dust-containing foul-smelling exhaust gases generated from garbage incinerators, scrap preheating furnaces, etc., have become increasingly important from an occupational health perspective. These odor components have become a problem not only in terms of pollution, but also in terms of environmental hygiene, and from the standpoint of pollution prevention, there is an urgent need to remove these foul-smelling components.

Conventionally, methods for removing these foul-smelling exhaust gases include (1) atmospheric diffusion using odor stacks, (2) direct combustion method (cleaning method using a 31 scrubber, and (4) adsorption method using adsorbents such as activated carbon. Each method has the following disadvantages: (1) method is ineffective except when the amount of bad odor generated is minute;
Method 1 requires high temperatures of 750 to 900°C, which is disadvantageous due to high fuel costs, and at the same time there is a risk of secondary pollution such as nitrogen oxide (NOx) by-products (Method 31 requires high costs for wastewater treatment) , (4) methods involve complicated operations such as regeneration and replacement of the adsorbent.

For the reasons mentioned above, there are very few cases in which these methods have been put into practical use as decisive methods for deodorization.

There is a catalytic combustion deodorizing method that improves the above-mentioned drawbacks, and this method uses relatively low temperatures (150 to 45
U ), fuel costs are low because it is effective, there is no need for secondary treatment such as wastewater treatment, and NOx is reduced because it is treated at low temperatures.
It has the advantage of not having to worry about by-products, and is currently in practical use.

The catalysts used in this catalytic combustion deodorization method are granular activated alumina supported with noble metals such as platinum and palladium, and base metals such as copper, chromium, and iron.Recently, catalysts used in automobile exhaust gas purification have also been used. Catalysts have been put into practical use in which activated alumina is supported on a cordierite honeycomb carrier with a small pore diameter, and noble metals such as platinum and palladium are supported in a thin layer on the surface. However, granular catalyst V has a large ventilation resistance and cannot process exhaust gas at a high linear velocity.Therefore, it is necessary to have a large exhaust gas flow cross-sectional area, which increases the area occupied by the reactor, and when treating exhaust gas containing dust. This has the disadvantage that the clogging increases ventilation resistance and increases running costs. On the other hand, when using a catalyst using a cordierite honeycomb type body, when treating dust-containing exhaust gas, the noble metal catalyst substance thinly supported on the surface is worn away and peeled off by the hard fine powder in the dust.
This causes a decrease in activity, and the small pore diameter causes an increase in ventilation resistance due to clogging.Furthermore, when exhaust gas containing several r/Nm3 of dust is vented to the catalyst, ventilation 1 to
It has drawbacks such as clogging that becomes unusable within two days.

More specifically, it is as follows.

Granular activated alumina, which has conventionally been used for deodorization, is used as a carrier, and precious metals such as platinum and palladium, copper,
Catalysts supporting base metals such as chromium and iron are generally 2
A grain size of ~6 mm is selected. However, this granular catalyst has a space velocity of 10.000 to 30.000 Hr l.
When using the catalyst layer, the catalyst layer length is limited to about 200% due to the ventilation resistance of the catalyst layer, which results in a large reactor installation cross-sectional area.In addition, scrap preheating furnace exhaust gas,
When processing foul-smelling exhaust gas containing a large amount of dust, such as garbage incinerator exhaust gas, sintering furnace exhaust gas, foundry exhaust gas, etc., even if the layer length is about 100 square meters, airflow resistance increases due to dust clogging in a short period of time, causing running problems. This increases costs and requires complicated operations such as frequent catalyst cleaning and catalyst replacement.

Regarding the conventional Ni-Cam type deodorizing catalyst, activated alumina is supported on a cordierite-based Ni-Cam type carrier with a pore number of 100 to 300 per square inch and a pore diameter of 1 to 2 mm. Generally used are metals with a thin layer of precious metals such as platinum or palladium supported on the surface.

When this catalyst is used to treat the above-mentioned dust-containing foul-smelling exhaust gas, there are problems such as abrasion of the surface noble metal catalyst by dust, performance deterioration due to peeling, and increased ventilation resistance due to clogging of the small pore size. This type of catalyst also has a space velocity of 10.000 to 50.000 Hr.
When used in a catalytic converter, the limit for the catalyst layer is about 400 mm due to the ventilation resistance of the catalyst layer, and as with granular catalysts, the device has the disadvantage of becoming large-scale.@The catalyst layer length must be shortened. In other words, the fact that the exhaust gas cannot be processed at a high linear velocity means that the gas flow inside the catalyst pores becomes more laminar and less turbulent, which is one of the causes of dust clogging. It also becomes. As a countermeasure against dust clogging, it is possible to use an electric precipitator, a bag filter, etc. to remove dust and deodorize it, but when using a bag filter, for example, the exhaust gas must be cooled once because its heat resistance is low. Since the exhaust gas is then removed from dust, it is necessary to heat the exhaust gas again by burning a fuel such as butane to the treatment temperature before it enters the catalyst layer, which increases fuel costs and running costs. It is extremely advantageous to deodorize by containing dust. Honeycomb-shaped mullite and alumina carriers with relatively large pores (about 4 mm pore diameter) have also been disclosed as deodorizing catalyst carriers, and catalysts in which catalyst materials are directly supported on these carriers are also considered, but mullite When a carrier is used, there are problems with the physical properties of the catalyst.

In this carrier, the BET surface area is less than Lm”/f,
The pore volume is as small as 0.25 cc/ or less, and it is difficult to achieve sufficient catalytic performance.
Further, even when an alumina carrier is used, there are problems in terms of wear resistance against poisoning and dust caused by SOx contained in exhaust gas.

Thus, in view of the above-mentioned drawbacks, the present invention can adopt a higher purity rate than these conventional products, and there is no performance deterioration due to abrasion or peeling of the catalyst material, especially when treating dust-containing exhaust gas.
Another object of the present invention is to provide a honeycomb type deodorizing catalyst that can prevent clogging due to dust.

The present invention is specified as follows.

Catalyst A component is at least one oxide selected from the group consisting of titanium, silicon, and zirconium, and catalyst B component is copper, chromium, iron, vanadium, tungsten, manganese, nickel, cobalt, molybdenum, and lead. A catalyst composition each comprising at least one oxide selected from the group consisting of: a catalyst composition formed into an integral structure having a plurality of through holes, the average pore diameter of which is in the range of 3 to 12III+ A honeycomb type deodorizing catalyst characterized by:

The present invention will be explained in more detail below.

For honeycomb catalysts, if the pore diameter (through-hole equivalent diameter) is increased, the ventilation resistance is proportional to the diameter, and clogging due to small particles can be prevented, but at the same time, the geometrical surface area of the catalyst is also reduced, and a certain level of In order to achieve treatment efficiency, it is necessary to increase the number of catalyst lids by increasing the pore size.
The pore size is limited in relation to treatment efficiency and catalyst performance.

As a result of extensive studies including the selection of catalyst materials, the present inventors discovered that a catalyst containing at least one selected from the oxides of component A and at least one selected from the oxides of component B was integrated into a honeycomb shape. Chemically molded with a pore diameter of 3 to 12 m
It has been discovered that a catalyst having a range of It has been reached.

Aluminum can also be used as the A component, but when aluminum is used alone, S contained in the exhaust gas
There are problems in terms of wear resistance against oxygen poisoning and dust, but when aluminum is used, it satisfies the purpose of the present invention when used in a mixed system with other component A. The shape of the through hole employed in the present invention may be square, hexagonal, wavy, or any other shape as long as its equivalent diameter is within the above range.

The ratio of the catalyst components used in the catalyst of the present invention is 30 to 99% by weight, preferably 40 to 99% by weight of component A in the form of oxide.
Suitable weight percentages for component B in oxide form range from 1 to 70 weight percent, preferably from 10 to 60 weight percent.

The starting material for the oxide can be appropriately selected from oxides, hydroxides, inorganic acid salts, organic acid salts, etc., especially ammonium salts, nitrates, sulfates, and halides.

Since the catalyst of the present invention is integrally molded with the catalyst material as described above, the catalyst material is uniformly distributed throughout the catalyst, and even if the surface layer is worn away or peeled off by dust, a new catalyst surface will not be exposed. Because of this, there is no performance deterioration due to wear or peeling, and the catalyst has a satisfactory lifespan.

The ventilation resistance of the catalyst of the present invention is 1/100 or less of that of a granular catalyst, and 1/10 or less of a conventionally used honeycomb catalyst with a relatively small pore size. /sec, whereas the catalyst of the present invention has a speed of about 10
A superficial velocity of m/sec can be obtained, and therefore the design of the catalytic reactor is easy, and a compact reactor with a vertically elongated structure and a small exhaust gas flow cross-sectional area can be manufactured.

In addition, as a method for preparing the catalyst of the present invention, TtOz-V2O3 system,
t'c is the T i O2S t 02 V 20 s system display tf. First, T t 02 or TtOz 5i02 is prepared. In the case of TtOz,
For example, ammonia is added to a titanium salt such as titanium tetrachloride or titanium borrowed acid to form a precipitate, and this precipitate is washed, dried, and then calcined at 150 to 850C.
I get it. In the case of TiO□-8i O2, similarly, titanium salt such as titanium tetrachloride or titanium sulfate is mixed with silica sol, and ammonia is added [7 to form a precipitate. This precipitate is washed and dried at 150 to 850°C. A sintered binary TiO2'5in2 oxide is obtained. T i 02 or TjOz-8iOz obtained by the above method is mixed with an aqueous solution containing a vanadium compound or an oxalic acid or hydrochloric acid aqueous solution, and an organic molding agent that can be decomposed and scattered during firing is added, such as methyl cellulose, polyethylene oxide, polyacrylic. Amide, polyvinyl alcohol, starch and an appropriate amount of water are added and thoroughly kneaded, followed by extrusion molding into a honeycomb mold.

It is also possible to add glass fiber, glass powder, etc. to increase the strength of the catalyst. After tightening, this molded body is 5
Dry at 0 to 150°C and further under an atmosphere with an appropriately controlled oxygen concentration at 300 to 700°C, preferably 350 to 60°C.
A desired catalyst can be obtained by calcining at 0'C for 5 to 10 hours, preferably 2 to 6 hours. In addition to this, the catalyst can also be prepared by directly kneading powder of TjOs or TtO, -8t, and powder of vanadium oxide.

When the catalyst components are multi-component, for example, TtO2-
V2O11CuO or TiO2-8tew V2O5
-CuO-based catalyst: T i 02 or T! in a solution containing a vanadium compound and a copper compound. 0z-8
It can be prepared by the method described above with the addition of jOz powder. Thus, the BET surface area of the catalyst of the present invention prepared by the method described above is 30 to 180 m"/?, and the pore volume is 0.
．． 3~0,5 cc/? have.

The exhaust gas to be treated using the catalyst of the present invention includes cresol, phenol, formalin, xylene,
Exhaust gas containing additives such as toluene and benzene, formaldehyde-containing exhaust gas emitted during the synthetic fiber manufacturing process, and exhaust gas containing various flammable organic compounds with strong pungent odors from the phthalic anhydride and maleic anhydride manufacturing process. , Resin Processing Gas, Other Craftsman Toyang, Chest Factory, City-
The catalyst of the present invention is a foul-smelling exhaust gas emitted from cleaning facilities, etc., and the catalyst of the present invention has a high dust content (5 to 4097 m'') such as scrap preheating furnace exhaust gas and garbage incinerator exhaust gas, and hard metal oxides such as iron oxide are contained in the dust. It is highly effective in treating foul-smelling exhaust gases that contain

Example 1 Binary oxide containing titanium and silicon (TiO□S
P;11 was prepared using the method described below.

Titanium tetrachloride [TiCl4:l l 1.4
Garlic was gradually added dropwise while stirring with water cooling, and then Snowtex-〇 (20 to 21
9 was added to 4.5 (weight percent content). While maintaining the temperature at about 30°C, aqueous ammonia was gradually added dropwise while stirring well, until the pH reached 7, and the mixture was left to mature for 2 hours.
The 25t02 gel was washed with water, dried at 120°C for 10 hours, and after further washing with water, it was calcined for 3 hours at 50°C.The composition of the resulting powder was oxidized. Tj0
2/S to2=4 (molar ratio).

420 t of oxalic acid was dissolved in 900 g of water, 214 f of ammonium metavanadate was added thereto, and to the dissolved solution, 1500 F of the above powder and 759 starch were added, mixed well, and kneaded well with a Nigu. After kneading while adding an appropriate amount of water, each hole diameter (equivalent diameter of the through hole) 4
am, 6 tm, 8 wn, each with a pore area of 64% 3
The product was extruded into a honeycomb mold of various types, dried at 120°C for 6 hours, and then fired at 450°C for 6 hours in an atmosphere with an oxygen concentration of 15% or less. The composition of the finished catalyst obtained was TiO25jOz:V2 in weight percentage as oxide.
0B=90:10 and BET surface area 120? F+2/l
, pore volume o, ascc/r.

Using this catalyst, forced abrasion and peeling tests were carried out for 100 hours under an air flow with a dust concentration of 10 t/N m3 and a superficial linear velocity of 35 m/sec. It was used for experiment-A). In addition, this catalyst was subjected to a forced clogging test (experiment-
B). For comparison, a similar test was conducted using a conventional type of honeycomb catalyst.

Conventional type honeycomb catalyst has an equivalent diameter of through holes of 1.5 m.
A cordierite honeycomb carrier of m (210 cells/square inch) on which activated alumina was supported and 0.3 weight percent (22 Pd/l) of palladium as a catalyst material was used.

Table 1 Test results (Experiment-A) Test conditions 5V=10,000 hr 1. temperature 3
5 (1, gas composition: aldehyde 300 ppm.

H*0 20% Residual air dust: average particle size 13μ (main component iron oxide) According to the test results above, the catalyst of the present invention showed no performance deterioration due to wear or peeling due to dust, whereas the conventional catalyst The performance deterioration was noticeable.

Table 2 Test Results (Experiment-B) According to the above test results, no clogging or increase in ventilation resistance was observed in the catalyst of the present invention, whereas the increase in ventilation resistance in the conventional catalyst was significant.

Example 2 Titanium oxide (TiO2) was prepared by the method described below. Titanium tetrachloride ['l'tC14:) 11
．． 9 was gradually added dropwise to 4 while stirring with water cooling, and the mixture was heated to a temperature of about 3.
While maintaining the temperature at 0° C. and stirring well, aqueous ammonia was gradually added dropwise until the pH reached 7, and the mixture was left to mature for 2 hours. Thus obtained T t 0
2 gels were washed with water, dried at 120°C for 10 hours, further washed with water, and then baked at SOO°C for 3 hours. Oxalic acid 42
07 was dissolved in 900 m of water, and 214f of ammonium metavanadate was added to the solution.
500f' and 75f of starch were added and mixed well, and kneaded well with a kneader. After kneading while adding an appropriate amount of water, the pore diameter (equivalent diameter of the through hole) was 4 m, 6 van.
, 8 tmv, three types of honeycomb molds with porosity of 64% were extruded, and after drying at 120°C for 6 hours, the oxygen concentration was reduced to 15%.
% or less at 450° C. for 6 hours.

The composition of the finished catalyst obtained is the weight percentage as oxides -
'c TiO2: V20==9o: lo -t'
BET surface area 60m2/l, pore volume o, a2cc/
It was r.

A treatment test similar to that in Example 1 was conducted using this catalyst.

Table 3 Test results Examples 3 to 5 Same as used in Example 1 T + 02- S j 02
Using powder, according to the preparation method of Example 1, TiO2-8
Catalysts were prepared by changing the catalyst components added to in2. Copper sheath acid, cobalt nitrate, and iron nitrate were used as starting materials. The composition of the finished catalyst found was TJO2-8i02:CuO-9o: 1o, respectively in weight percentage as oxides.
TiO2-8j02-CoO=90:10, TiO2-
8iO□:Fe203=90:10 B E T fi
The total area is approximately 125m2/? The pore volumes were all approximately 37 cc/y.

A treatment test similar to that in Example 1 was conducted using the catalyst.

Table 4 Test results

Claims (1)

[Claims] (1) As the catalyst A component, at least 1fiJi selected from the group consisting of titanium, silicon, and zirconium.
Copper, chromium, iron,
a catalyst composition each comprising at least one oxide selected from the group consisting of vanadium, tungsten, manganese, nickel, cobalt, molybdenum, and lead; A honeycomb-type deodorizing catalyst characterized in that it is shaped and has an average pore diameter in the range of 3 to 12+ m.