JPH02184342A - Catalyst for denitrification of stack gas - Google Patents

Abstract

PURPOSE:To render denitrifying performance comparable to that of the conventional catalyst and to reduce the rate of oxidation of SO2 by incorporating II-type anhydrous gypsum, titanium oxide and the oxide of Sb, Zn, etc., in specified ratios and further incorporating the oxide of V, W, etc. CONSTITUTION:This catalyst for denitrification of stack gas used to remove NOx in exhaust gas contains >=70wt.%, in total, of II-type anhydrous gypsum (A), titanium oxide (B) and the oxide (C) of Sb, Zn, Al, etc., in 0.01-0.4 weight ratio of B/(A+B+C) and 0.005-0.4 weight ratio of C/(A+B+C) and further contains the oxide of V, W, Fe, Cu, etc. This catalyst has denitrifying performance comparable to that of the conventional catalyst and is very effective in reducing the rate of oxidation of SO2.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to the treatment of nitrogen oxides in exhaust gas discharged from internal combustion equipment such as boilers, gas turbines, or diesel engines. This invention relates to a denitrification catalyst that removes denitrification.

[Conventional technology]

The mainstream method for removing nitrogen oxides from wandering gas is to add ammonia to the LQ-containing exhaust gas, catalytically reduce the nitrogen oxides on a catalyst, and decompose them into nitrogen and water. There is. Catalysts used to remove nitrogen oxides from exhaust gas are known to have titanium oxide as the main component and contain vanadium, tungsten, molybdenum, etc. as active metal components. It is also known that the effect of removing atomized substances is slowed down.

This catalyst is formed into a catalyst molded body in the form of parallel arrays of lattice-shaped honeycomb plates by extrusion molding, in order to prevent clogging due to dust components in the exhaust gas, and to reduce the pressure loss of the exhaust gas. has been done.

However, when this layered titanium-based catalyst is formed into a honeycomb shape, in order to maintain a good shape and obtain high strength, drying after extrusion is difficult. 41j It is requested to take sufficient time and do it carefully without causing any harm.
Manufacturing was not always easy. In addition, although the entire catalyst is made of titanium oxide, which is a relatively expensive material, and other active ingredients, the portion that contributes to the denitrification reaction of the catalyst molded body is located within 100μ from the surface of the catalyst molded body. 1・4
1i+1 problem was that expensive materials were not being used effectively.

In view of these problems, a catalyst using a stone arm as a carrier has recently been proposed. (For example, the special
(Refer to the following publications: No. 06, No. 60-12909) This proposed catalyst is prepared by mixing stratified titanium and vanadium sulfate IV with dihydrate gypsum and hemihydrate gypsum as gypsum and distributing water thereon.
After kneading and extrusion molding, it is heated and molded at 120 to 350°C. Furthermore, the inventors have also proposed that a catalyst using type 1 anhydrite is easier to handle during production of hornworm medium than other types of stone, and has sufficient strength, so that it is practical. (See Tokuton Sho 62-304770).

[Problem to be solved by the invention]

Of course, the denitration catalyst is required to have excellent nitrogen oxide removal performance, but another condition is that if the exhaust gas contains sulfur oxides, SO2
0. It is desired that the ability to oxidize to S03 is equipment such as piping in the back canal of the denitrification equipment.
- Avoid touching the SO□ 800 as much as possible to prevent
This is because there is a need to control the re conversion to 3+JI.

The inventors had previously proposed a catalyst using ■-type anhydrite (
After further examination, it was found that the 80□ oxidation rate of 1 ton of oxidation to SO3 is large compared to conventional catalysts mainly composed of titanium oxide. did.

[Means to avoid losing one problem] The present invention! r: The catalyst of the present invention was developed after extensive research in order to improve the following drawbacks, and the catalyst of the present invention was previously proposed: At least one of the oxides of tin, zinc, aluminum, titanium and zirconium or H
802-802-802-8
This is a catalyst that suppresses oxidation to 03.

That is, the present invention provides (1) +I tank;! = A component consisting of waterstone bone, B component consisting of titanium oxide, tin, zinc, aluminum,
The sum of the C component consisting of at least one of C1β compounds of titanium and zirconium is at least 70
% or more, and the ratio of B/(A, +B+C) is 001 to 0.4. (H1B-)C) C/weight N°C ratio is 0005 to 0.4, and one or more of vanadium tungsten, molybdenum, iron, copper, chromium, and manganese oxides are also present. A flue gas denitrification catalyst characterized by comprising: 2) component A consisting of ■-type anhydrite; 1. The sum of the B component consisting of stratified titanium and the C component consisting of H-type zeolite is at least 70% or more, and B/(A
+B+C) Weight pressure is 0.01 to 0.4 °/(A, +
B-1-C) A ferric acid ratio of O, OO5 to 0.4 f, l, and further containing at least one of vanadium, tungsten, molybdenum, iron, copper, chromium, and manganese oxides. This is a flue gas denitrification catalyst.

[Effect]

(A+B+C) When the grinding ratio is less than 5 or 0.01, the media activity decreases rapidly, and when the grinding ratio is 0.4 or more, the extruded product tends to crack during drying.

Although it is not clear why the increase in the length of 1m from S02 to S03 is large, one of the factors is that Ca, which forms stone 4,
This is expected to be due to the improvement in SO2 oxidation activity due to the formation of compounds such as vanadium and tungsten (mainly Ca ions), which are catalytically active components, which are eluted when S04 is mixed with water during catalyst production.

As described in this text, when one or more of the oxides of tin, bent lead, aluminum, titanium, and zirconium is added as component C to type II anhydrite, which is component A, these Covers the surface to suppress the generation of Ca ions and suppress SO2 oxidation activity! When HgJ-type zeolite is added as a sintered C component, these give acid points around the catalytically active component, and the catalytically active component forms a compound. , Ca ions can be adsorbed and removed to maintain the catalytic active components in the deposit.

C component is tin, ε(1, aluminum, titanium,
When one or more of the oxides of zirconium is C/, (A, +B-1-C) the ton-ta ratio is 0
．． If it is less than 005, suppression of Ca ions is insufficient, and if the C component is H-type zeophyte, C/
(mu, +'s+c) When the mastication ratio is less than 0.005, the H-type zeolite has fewer free points, so 5O2r
*In any case, the C component is C/(A
+B+C) When the fi'lJt ratio is 0.4 or more, problems arise in terms of strength when producing a honeycomb-shaped catalyst. In addition, the above C component may be added after mixing A component and B component, and there is almost no difference in the preparation procedure.
Ha. In addition, the H-type zeolite that can be used is a zeolite that has solid acidic points, such as Y-type, X-type, L-type, L-type zeolite.
Type, TMAn type, ZSM-5 type, ZSM-20,! Examples include zeolite 1- such as L, heptarudenite, and ferrierite.

(Actual/7i!i Example 1) Titanium oxide powder was impregnated with a 10% methylamine water bath solution of metavanazine 1 ammonium and ammonium paratungstate, and after drying, it was baked at 450° C.
Titanium oxide powder containing 55 wt% O and 38 wt% WO was obtained.

■Type suiseki impregnated with this titanium oxide powder & 2 ichikai part and zirconium oxychloride aqueous solution-1#: (Zr02 5
58 parts by weight of gypsum), 4 parts by weight of kaolin, and 2 parts by volume of glass fiber, and then 16 parts of water and 68 parts of organic binder component were added. After kneading with a kneading machine, it was extruded into a cylindrical pellet of 3 mm φ x 5 w 1 IL, and after being air-dried day and night, it was heated at 550"C in an electric furnace.
It was baked for 3 hours. This catalyst will be referred to as catalyst A.

(Example 2) In Example 1, ammonium molybdate was used instead of paratungsten ammonium, and V2O6
Titanium oxide powder containing 3 wt% and 38 wt% of MoO was obtained, and a catalyst was prepared using the same procedure.

This catalyst will be referred to as catalyst B.

(Example 3) Adding ■-type hydrochloride to the zirconium oxychloride aqueous solution,
Further, NH3 water was added to form a zirconium hydroxide precipitate, and the dropping of NH was stopped at pH = 8.751: Purification, filtration, drying and firing (450''C for 13 hours), and the crushed stone coated with zirconium oxide. This material (■ type suiseki #58 parts by weight, i snowized zirconium 5 parts by weight) was thoroughly mixed with 2 parts by weight of acclimatized titanium A, 4 parts by weight of kaolin, and 2 parts by weight of glass fiber. After that, a 10% methylamine water bath solution of paratungsten ammonium containing 07 parts of WO3 and a 10% methylamine water bath solution containing metavanadine ammonium containing 0.25 parts by weight of V2O5 and 10 parts by weight of water. After adding and mixing #! machine, 5w1Iφ
Extrusion molded into a cylindrical pellet of X 5 mm L, -
After drying day and night, it was fired in an electric furnace at 550°C for 3 hours. This total catalyst is referred to as catalyst C.

(Example 4) In Example B, instead of using a 10% methylamine aqueous solution of paratungsten ammonium, a 10% methylamine aqueous solution of ammonium molybdate containing 08 parts of MoO3 was used, and the same solution was used. A catalyst was obtained in step 1; d. This catalyst is called a catalyst.

(Fire hair row 5) In Example 6, ammonium paratungstate 1
Instead of using a 0% methylamine aqueous solution, use a chromium nitrate aqueous solution containing 1.5 parts of Fe203, an aqueous solution of copper chloride containing 1.3 parts of CuO, and an aqueous solution of chromium nitrate containing 1.5 parts of CuO. Catalysts were prepared in the same manner using 1 volume of manganese soybean water containing 1.04'i Takebe's 14002. Catalyst E, Catalyst F,
Let them be a catalyst G and a catalyst H.

(Example 6) In Example 3, aluminum nitrate, titanium sulfate, stannic chloride, and nitrate were used in place of zirconium oxychloride, and plaster was covered with metal oxide and chloride using the same method. and prepared Al2O2゜T 1102 + S n
Catalysts were prepared in which each part by weight of O2, Z, and nO was 3.4.6.5 parts by weight. Catalyst engineering and catalyst J
One catalyst per catalyst.

(Comparative Example 1) In each of Examples 1 to 6, catalysts containing no metal or oxide as the C component were prepared, and catalysts M, N, and 0 were prepared, respectively.
shall be.

(Test Example 1) The denitrification rate, SC2 and oxidation rate of catalyst A-0 were measured under the following conditions, and the results shown in Table 1 were obtained.

Conditions: Mouthworm It: 20m/!
802:800 °Cram()T(SV
: 20000hr O, : 5% temperature JJi
: 380°CCo□:10%NO:200ppm
H2O: 10% NH3: 200 ppm
Remainder 2N2 Table 1. Denitrification rate and SO□ oxidation rate measurement results (Example 7) Titanium oxide powder was impregnated with a 10% methylamine aqueous solution of ammonium metavanadate, paratungsten, and ammonium, dried, and fired at 450°C for 5 hours to form a V2O
Titanium oxide powder containing 53 wt% and 38 wt% of WO was obtained.

This titanium oxide powder II 2 Iij j['f,'r
:) S and n and Anhydrous old edition 58 @Okibe, H-Y yarn zeolite 5-fold eye part, kaolin 4/F isthmus part, glass iron who 2 city are mixed in the proportion of 16 parts, and then with water 16 Dong-Euro part Add 68 tons of organic binder component, mix in a freezing machine, add 3-sφ
X 59 T- extruded into cylindrical pellets F) W, -
After drying in the afternoon, it was fired in an electric furnace at 550°C for 5 hours.

This catalyst will be referred to as catalyst A'.

(Big Flag I!A, l 8) ゛In accordance with Example 7, using molybdenum and ammonium in place of paratungsten,
A catalyst was prepared using titanium oxide powder containing 0.063 wt% and 38 wt% MoO in the same 1:1 tli.

This 9-insect medium is designated as I111I medium B'.

(Example 9) ■ Type Suiseki X58 tun (Yabe, H-Y type zeophyte 5 Shitakebe, titanium oxide 7,3 parts by weight, kaolin 4iJi,
: After thoroughly mixing 1 part of glass fiber and 2 parts of glass fiber,
．． A 10% aqueous methylamine solution of ammonium paratungstate containing 7 parts by weight of WO3 and ammonium paratungstate containing 0.2 parts by weight of 205.
Add the solution and 10 parts of water to 1 part of 0% methi-7-reamine, mix with a kneader, extrude into a cylindrical pellet of 31φ x 5wL, and after drying in the air for days and nights, heat in an electric furnace at 550°C. ,3
Baked for an hour.

This catalyst will be referred to as catalyst C'.

Example 10 In Example 19, instead of using a 10% methylamine water bath solution of ammonium paratungstate, aS
A catalyst was obtained in the same manner using a 10% aqueous solution of methylamine containing molybdenum and ammonium. This catalyst will be referred to as catalyst D'.

(Example 11) Instead of using a 10% aqueous methylamine solution of paratungsten f-ammonium at M/Mul 9, an aqueous solution of ferric chloride containing 1.5 parts Fe2O3, 1.3 wt. Copper chloride aqueous solution containing 1.5 parts of Cu and O
The city is using 1llll aqueous chromium solution, 1.0 tl.
i: Catalysts were prepared in the same manner using an aqueous manganese chloride solution containing a certain amount of Mn 02. The respective catalysts are referred to as catalyst F', catalyst F', catalyst G', and catalyst H' in this order.

(Example 12) In Example 9, instead of H-Y type zeophyte, H-
Using Z SM-5, H-L type zeolite, H type mordenite, and ferrierite, 3 tons of soft part, 4 parts of soft part, 6 parts by weight, and 5 parts by weight were added, and 1 part by weight of the catalyst was added in the same manner.
．． Made in IL. For each catalyst: 1i [i to i・+llll medium■
', catalyst J', catalyst ', and catalyst L'.

(Comparative Example 2) No Y-type zeolite was added in each of Examples 7 to 9. 11! Prepare catalysts, respectively catalyst M', catalyst N', catalyst 0.
'.

(Trial) Example 2) The denitration rate and SO□ oxidation rate were measured for catalysts A' to O' under the conditions shown in Trial Example 1, and the results shown in Table 2 were obtained.

Table 2 De-f11′] rate sentence and SO□1・Sanka-Pak measurement results [
[Effects of the Invention] As is clear from Tables 1 and 2, the catalyst of the present invention has a higher denitrification effect than a catalyst that does not contain tin, zinc, aluminum, titanium, or zirconium oxides or H-type zeolite. There is almost no difference in performance, and the effect of reducing the SO2 dredging rate is appropriate, making it a practical dredging/reduction catalyst.

Claims (2)

[Claims] (1) Component A consisting of type II anhydrite, component B consisting of titanium oxide, and tin, zinc, aluminum, titanium,
The sum of the C component consisting of at least one kind of zirconium oxide is at least 70% by weight or more,
B/(A+B+C) weight ratio is 0.01 to 0.4, C/(
A+B+C) A flue gas denitrification catalyst having a weight ratio of 0.005 to 0.4 and further containing at least one of vanadium, tungsten, molybdenum, iron, copper, chromium, and manganese oxides. . (2) The sum of component A consisting of type II anhydrite, component B consisting of titanium oxide, and component C consisting of type H zeolite is at least 70% by weight, and B/(A
+B+C) weight ratio is 0.01 to 0.4, C/(A+B+
C) A flue gas denitrification catalyst having a weight ratio of 0.005 to 0.4 and further containing at least one of vanadium, tungsten, molybdenum, iron, copper, chromium, and manganese oxides. .