JPH07275712A - Production of zeolite denox catalyst - Google Patents

Abstract

PURPOSE:To produce a zeolite denox catalyst having purifying function of a gas containing NOx. CONSTITUTION:A powdery catalyst material obtained by exchanging ionically Y type zeolite or USY type zeolite with an ion of a metal selected from the group consisting of Cu, Ce, Co and Fe is formed by using a molding assistant consisting of smectite group Ca<2+> monmorillonite or smectite group NH4<+> monmorillonite obtained by exchanging ionically with Ca<2+> ion or NH4<+> ion and glass fiber chop driver, then the formed body is immersed in an aq. soln. containing metal ion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a zeolite denitration catalyst having a purifying effect on exhaust gas containing NOx.

[0002]

2. Description of the Related Art Currently, the denitration catalyst of NOx contained in the combustion exhaust gas, TiO ₂ mainly composed of TiO ₂ -
WO ₃ -V ₂ O ₅ based catalysts are used. These catalysts are usually formed in a honeycomb shape having a large gas contact area and a small pressure loss. Zeolite catalyst is Ti
It has an excellent feature that it can be applied at high temperature such as high temperature exhaust gas temperature of gas turbines (up to 600 ° C) compared to O ₂ catalyst at low cost, but honeycomb forming is generally difficult because it is hydrophobic, and active. Since the metal is unstable in the crystal lattice, it is easily eluted during the honeycomb formation process, and it is difficult to maintain the activity of the catalyst powder until after the honeycomb formation.

[0003]

DISCLOSURE OF THE INVENTION The present invention intends to provide a method for producing a denitration catalyst which maintains the excellent catalytic activity of a zeolite catalyst powder until after molding, has a low cost, high strength and is excellent in denitration performance. Is.

[0004]

The present invention provides a catalyst powder material obtained by ion-exchange of Y-type zeolite or USY-type zeolite with ions of a metal selected from the group consisting of Cu, Ce, Co and Fe, Smectite group Ca ²⁺ montmorillonite or smectite group NH ₄ ⁺ montmorillonite ion-exchanged with ^{2 +} ions or NH ₄ ⁺ ions is molded with a molding aid composed of glass fiber chop driver and soaked in an aqueous solution containing the metal ions. A method for producing a zeolite denitration catalyst, which is characterized in that

The Y-type zeolite used in the present invention has the same crystal structure as natural faujasite, and has a SiO ₄ / Al ₂ O ₃ content of about 5 (SiO ₄ / Al ₂
O ₃ weight ratio: 4 to 6), and USY-type zeolite is heat-stabilized by heat-treating Y-type zeolite to dealuminate it and increase SiO ₄ / Al ₂ O ₃ (weight ratio). (SiO ₄ / Al ₂ O ₃ weight ratio: 5
~ 80). A catalyst powder material comprising Y-type zeolite or USY-type zeolite ion-exchanged with ions of a metal selected from the group consisting of Cu, Ce, Co and Fe, and Ca
Smectite group Ca ²⁺ montmorillonite or smectite group N ion-exchanged with ²⁺ ion or NH ₄ ⁺ ion
The mixing ratio of the molding aid composed of H ₄ ⁺ montmorillonite (hereinafter, simply referred to as Ca ²⁺ montmorillonite and NH ₄ ⁺ montmorillonite) is the former: the latter = 70 to 90%: 10.
The glass fiber chop driver is preferably 15% (weight ratio) or less with respect to the catalyst powder.

[0006]

The smectite group montmorillonite used as a molding aid in the present invention is Ca ²⁺ ion or NH ₄ ⁺
The purpose of ion exchange with ions is to remove Na ⁺ ions which are catalyst poisons which are constituents of the smectite group montmorillonite, and enhance the activity and durability of the catalyst of the present invention.

When the zeolite used in the present invention is catalyzed by ion exchange, it exhibits higher denitration performance in the powder state than the conventional TiO ₂ catalyst due to its large specific surface area and solid acidity (Y type). See Fig. 1 for zeolite and Fig. 4 for USY type zeolite). However, in the process of honeycomb formation, the active metal is unstable in the crystal lattice, so that the active metal is easily eluted and the performance deteriorates (see FIG. 2 for Y-type zeolite and FIG. 5 for USY-type zeolite). Therefore, the present invention is intended to maintain the high catalytic performance of the catalyst powder until it is honeycombed by catalyzing the zeolite catalyst raw material powder by active metal ion exchange, molding it with a molding aid, and then impregnating it in an aqueous solution containing active metal. (See FIG. 3 for Y-type zeolite and FIG. 6 for USY-type zeolite).

[0008]

EXAMPLES The effects of the present invention will be clarified by giving concrete examples of the present invention. (Example) Ion exchange with Cu, Ce, Co and Fe as catalyst powder raw materials (degree of ion exchange is 10 to 50%)
The above Y-type zeolite, Ca ²⁺ montmorillonite or NH ₄ ⁺ montmorillonite as a molding aid, and a glass fiber chop driver having a length of 5 mm were used. The ion-exchanged Y-type zeolite: Ca ²⁺ montmorillonite or NH ₄ ⁺ montmorillonite is mixed in a proportion of 70 to 90%:
The amount of the glass fiber chop driver was 10% to 30% (wt%), and the amount of the glass fiber chop driver was 15% (wt%) or less with respect to the catalyst powder.

In addition to the above, although not limited to the present invention, materials and procedures for preparing a honeycomb shape as a product will be shown. 7 parts by weight of methyl cellulose was added as a binder for imparting plasticity to the product of the present invention and having a factor of honeycomb formation (hereinafter, the addition amount is based on 100 parts by weight of the components). value.). In addition to this, 3 parts by weight of glycerin was added. The two components were fixed, and in addition to this, cellulose (trade name: Avicel), pulp fiber, and the like were added as a porosity-imparting material as needed, and water was added to these ingredients to mix. The amount of water added is about 4
The amount was increased or decreased while observing the kneading state based on 0 part by weight. The above materials were sufficiently kneaded to give plasticity, and then formed into a honeycomb shape with a mold having a cross-sectional size of 150 mm square in outer dimension, 1 mm in wall thickness, and 6 mm in pitch. This is 500mm
After molding based on the length, it was dried. This dried honeycomb was fired at 650 ° C. for 4 hours to obtain a fired body. About 1 part of the obtained fired body was added to an aqueous solution of Cu, Ce, Co and Fe acetate or nitrate (metal salt concentration: 0.01 to 0.2 wt%).
Impregnate for 5 hours. After impregnation, remove the fired body from the solution,
Wash with about 10 liters of pure water. Then, dry it to 65
A test body was obtained by firing at 0 ° C. for 1 hour.

FIG. 1 shows the results of catalytic performance tests of the conventional TiO ₂ catalyst and the zeolite catalyst of this example in powder form. From FIG. 1, it can be seen that in the powder state, any Y-type zeolite catalyst has higher performance than the conventional TiO ₂ catalyst. FIG. 2 shows the results of performance tests of the honeycomb structure after ion exchange. As shown in FIG. 2, after the honeycomb formation, the Y-type zeolite catalyst cannot maintain the catalytic performance as a powder and is deteriorated, which is lower than that of the conventional TiO ₂ catalyst. FIG. 3 shows an example in which the catalyst performance was evaluated after impregnation in an active metal solution after honeycomb formation. As shown in Fig. 3, the catalytic performance of the Y-type zeolite, which had been reduced after the honeycomb formation, was recovered by further impregnation, and the performance was as high as that in the catalyst powder state.
Higher performance than the O ₂ catalyst was observed.

Further, FIGS. 4 to 6 show the case of another embodiment using USY type zeolite as a catalyst carrier.
The manufacturing method is exactly the same as in the above embodiment. It can be seen that the denitration performance is not inferior to that of the Y-type zeolite.

[0012]

EFFECT OF THE INVENTION According to the present invention, it is inexpensive and in a high temperature range (up to 60
A method for producing a zeolite denitration catalyst that can be used up to 0 ° C.) can be provided, and its industrial effect is remarkable.

[Brief description of drawings]

FIG. 1 is a chart showing the denitration performance of powder after Y-type zeolite catalysis according to one embodiment of the present invention.

FIG. 2 is a chart showing denitration performance after forming a Y-type zeolite honeycomb according to an embodiment of the present invention.

FIG. 3 is a chart showing the denitration performance after impregnation of Cu, Ce, Co or Fe into a honeycomb-shaped Y-type zeolite according to an example of the present invention.

FIG. 4 is a chart showing the denitration performance of the powder after catalyzing a USY-type zeolite according to another example of the present invention.

FIG. 5 is a chart showing denitration performance after forming USY-type zeolite honeycomb according to another embodiment of the present invention.

FIG. 6 is a chart showing denitration performance after impregnation of Cu, Ce, Co or Fe into honeycomb-shaped USY type zeolite according to another example of the present invention.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location B01J 29/70 ZAB A 37/00 H (72) Inventor Osamu Naito No. 1 Atsunoura Town, Nagasaki City, Nagasaki Prefecture No. 1 Mitsubishi Heavy Industries, Ltd. Nagasaki Shipyard (72) Inventor Toshiyuki Onishi 1-1, Atsunoura-machi, Nagasaki-shi, Nagasaki Mitsubishi Heavy Industries Ltd. Nagasaki Shipyard

Claims (1)

[Claims] 1. A catalyst powder material obtained by ion-exchanging Y-type zeolite or USY-type zeolite with ions of a metal selected from the group consisting of Cu, Ce, Co, and Fe,
Smectite group Ca ²⁺ montmorillonite or smectite group NH ion-exchanged with ^{2 +} ion or NH ₄ ⁺ ion
_A method for producing a zeolite denitration catalyst, comprising molding with a molding aid composed of ₄ ⁺ montmorillonite and a glass fiber chop driver, and then immersing it in an aqueous solution containing the ions of the metal.