JPH0563222B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a simultaneous treatment catalyst suitable for removing CO and _NOx from exhaust gas of gas turbine waste heat boilers and the like. [Conventional technology] To counter nitrogen monoxide (hereinafter abbreviated as NO) in gas turbines, there is a method of improving it by combustion in a burner, and a method of catalytic reduction using ammonia to meet more stringent requirements that cannot be achieved by improving combustion. . This catalytic reduction method involves injecting ammonia from the front of the catalyst layer and reducing it to nitrogen and water in a temperature range of 250 to 500°C according to the following chemical formula. 4NO+4NH ₃ +O ₂ →4N ₂ +6H ₂ O As a catalyst in this case, for example, a catalyst material consisting of vanadium (V) and phosphorus (P), or a catalyst material consisting of vanadium (V) and phosphorus, in addition to molybdenum (Mo), tungsten (W), titanium ( At least one element selected from the group consisting of Ti), tin (Sn), and cerium (Ce) (Japanese Patent Application No. 106389/1989), or vanadium (V) on a carrier material such as alumina titania. , chromium (Cr),
Supporting at least one catalyst substance selected from metal compounds of manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), and copper (Cu) (Japanese Unexamined Patent Publication No. 52-61192) Denitrification catalysts have been proposed, such as: However, although the catalysts prepared according to the above-mentioned production methods have excellent denitrification activity, CO combustibility is poor.
rare. On the other hand, carbon monoxide (hereinafter abbreviated as CO) in exhaust gas
is oxidized and treated as carbon dioxide at a temperature of 180 to 800°C in the presence of a Pd or Pt-based catalyst. CO+1/2O ₂ →CO _2This palladium (Pd) and platinum (Pt) based catalyst has good CO combustibility, but has almost no denitrification performance. Therefore, conventionally, the denitrification reaction and the CO combustion reaction were processed in separate processes. Therefore, it was necessary to provide separate processing equipment for each, and catalysts were also prepared for each. In response, the present inventors investigated a catalyst for simultaneous treatment of NO _x and CO. In the first place, the denitrification reaction
Since the CO combustion reaction is a reverse reaction of reduction and oxidation, and the denitrification reaction tends to involve side reactions, selecting the catalyst configuration was extremely difficult. As a catalyst for simultaneous treatment, selectivity is important: NO+1/4NH ₃ →5/8N ₂ O+3/8H ₂ O NO+1/2O ₂ →NO ₂ NH ₃ +5/4O ₂ →NO ₂ +3/2H ₂ This is because when dinitrogen monoxide (N ₂ O) and nitrogen dioxide (NO ₂ ) are generated due to side reactions such as O, additional equipment is required to process these gases, leading to an increase in the cost of exhaust gas treatment equipment. be. Furthermore, when ammonia (NH ₃ ) is consumed by the side reactions mentioned above, the denitrification reaction (4NO+
Since the ammonia used for 4NH ₃ +O ₂ →4N ₂ +6H ₂ O decreases, it is necessary to supply excessive ammonia in order to maintain a predetermined denitrification rate, and running costs also increase. Under these circumstances, the present inventors developed a high-performance NO _x ,
We have discovered a catalyst for simultaneous CO treatment. [Problems to be Solved by the Invention] The present invention provides a catalyst for the simultaneous treatment of _NOx and CO that allows the denitrification reaction and the CO combustion reaction to proceed simultaneously at a high conversion rate and has the selectivity to suppress side reactions. This is what I am trying to do. [Means for Solving the Problems] The present invention provides a titanium oxide support containing at least one oxide selected from the group consisting of tungsten, tin, aluminum, zirconium, cobalt, and zinc. A catalyst for the simultaneous treatment of nitrogen oxides and carbon monoxide, characterized in that it supports a catalyst material consisting of at least one oxide selected from the group consisting of copper, iron, tin, nickel, chromium, barium, and zinc. be.
Note that the carrier contains 0.01 to 1 part by weight, preferably 0.05 to 0.3 part by weight of the above carrier material per 1 part by weight of titanium oxide.
The weight part is added, and the shape can be an appropriate shape such as a lattice-like honeycomb shape. Next, a method for producing the catalyst will be explained. A titanium oxide carrier containing one or more selected from tungsten oxide, tin oxide, aluminum oxide, zirconium oxide, cobalt oxide, and zinc oxide can be used after firing, even if the titanium oxide contains tungsten oxide, etc. They can be manufactured by various methods. For example, it can be obtained by the following method. Titanium oxide powder, tungsten oxide, tin oxide, aluminum oxide, zirconium oxide,
A method in which one or more powders selected from cobalt oxide and zinc oxide are dry-mixed or wet-mixed, and then shaped and fired. Titanium oxide powder is immersed in an aqueous solution containing one or more elements selected from tungsten, tin, aluminum, zirconium, cobalt, and zinc, which become oxides when fired, and dried or fired, then shaped, and then dried or How to bake. When molding titanium oxide powder, an aqueous solution containing one or more elements selected from tungsten oxide, tin oxide, aluminum oxide, zirconium oxide, cobalt oxide, and zinc oxide is added to the binder liquid, and then the powder is molded. Method of dry firing. The catalyst of the present invention can be produced by calcination of the carrier obtained by the above-mentioned method to produce V, W, La, Co, Cu, Fe,
After being immersed in an aqueous solution containing a metal or metal compound that converts into oxides of Sn, Ni, Cr, Ba, and Zn, drying and firing are performed to produce a co-treated catalyst. [Example 1] An activity evaluation test was conducted to examine the denitrification rate and CO combustion rate using the catalysts shown in No. 1 to No. 31 in Table 1. The composition of the catalyst is a lattice-shaped support made of titanium oxide, tungsten oxide, tin oxide, ammonium oxide, zirconium oxide, cobalt oxide, and zinc oxide, and vanadium, tungsten, and catalytic materials as catalyst materials.
It supports oxides of lanthanum, cobalt, copper, iron, tin, nickel, chromium, barium, zinc, etc., and the weight ratios are as shown in Table 1. The above catalysts No. 1 to No. 31 were mixed with CO 200ppm, _NO
An activity evaluation test was conducted using exhaust gas containing 200 ppm at normal pressure, gas hourly space velocity (SV) of 2000 hr ^-1 , and reaction temperature of 350°C. The results are shown in Table 1. However, the amount of ammonia injected was 200 ppm. [Example 2] The catalyst prepared in Example 1 was mixed with 200 ppm of CO,
An activity evaluation test was conducted on exhaust gas containing 200 ppm of NO _x at normal pressure, gas hourly space velocity (SV) of 2000 hr ^-1 , reaction temperature of 350°C, and injected ammonia of 180 ppm. The results are shown in Table 2. [Example 3] The catalyst prepared in Example 1 was mixed with 200 ppm of CO,
An activity evaluation test was conducted on exhaust gas containing 200 ppm of NO _x at normal pressure, gas hourly space velocity (SV) of 2000 hr ^-1 , reaction temperature of 400°C, and injected ammonia of 200 ppm. The results are shown in Table 3. [Effects of the Invention] By employing the above configuration, the present invention has the following effects. (1) By adding CO oxidation performance and denitrification performance to the same catalyst, the amount of catalyst is reduced to about 50-80% compared to conventional methods (individual treatment of CO and _NOx ). (2) When carried out alone, the side reaction from NH ₃ to NO is CO
Although generated on a combustion catalyst, almost no side reactions occurred with the catalyst according to the present invention. (3) Since it is sufficient to fill the reactor with the same catalyst,
The filling operation was easy.

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Claims (1)

[Claims] 1. Vanadium, tungsten, lanthanum, cobalt,
A catalyst for the simultaneous treatment of nitrogen oxides and carbon monoxide, characterized in that it supports a catalyst material consisting of at least one oxide selected from the group consisting of copper, iron, tin, nickel, chromium, barium, and zinc.