JPH01180251A - Production of molded body for cleaning up exhaust gas - Google Patents

Abstract

PURPOSE:To stably and efficiently remove NOx in exhaust gas by carrying alkali metal and transition metal including group 1B and 2B elements in the periodic table and tin on carrier carbon and molding with heat-resistant substance and water glass. CONSTITUTION:The NOx remover is produced by using carbon as carrier and impregnating the carrier with the alkali metal element and one or two or more kinds of element selected from the group consisting of transition elements including group 1B and 2B elements in the periodic table such as Ni, Fe, and tin. The remover is added and mixed with the heat-resistant substance such as Al2O3, SiO2 and water glass as binder, and press molded into a specified shape. The molded body for cleaning up exhaust gas can remove NOx in exhaust gas stably and efficiently even at a high temp. range without supplying reducing gas from the outside. Besides, it has excellent heat-resistance and mechanical strength.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a method for producing a molded article for purifying exhaust gas, and more specifically, the present invention relates to a method for manufacturing a molded article for purifying exhaust gas, and more specifically, a heat-resistant substance and water glass are used as a purifying agent for purifying nitrogen oxides in exhaust gas. The present invention relates to a method for manufacturing a molded body for exhaust gas purification, which is made by adding .

(Conventional technology and problems) For environmental protection, N01No2 contained in combustion exhaust gas
Nitrogen oxides (hereinafter referred to as NoX) must be reduced to nitrogen and rendered harmless before being discharged into the atmosphere. As a dry method for removing nitrogen oxides from exhaust gas from factories, etc., N) 1. The reduction method is often used.

Since this method uses NH, great care must be taken to ensure its safety, and leakage of the introduced NH poses a major problem, resulting in a large-scale removal system and increased cost.

As a method for removing NOx at a relatively low temperature without using NH, etc., there is a method in which NOx is reduced and removed in the range of 150 to 400° C. using a carbon-based removal agent carrying an alkali metal, a transition metal, etc. (Patent application 6l-315176), L
However, the shape of the removing agent is granular, etc., which inevitably causes a large pressure loss and reduces combustion efficiency.Furthermore, dust and vibration in the gas cause abrasion and the removing agent becomes pulverized, further increasing the pressure loss. becomes large. Furthermore, since it has low mechanical strength, it is broken and pulverized during transportation or when packed into equipment, resulting in a large pressure loss as described above.

(Objective) The present invention solves the problems of conventional NO8 removers as described above, and eliminates NO8 in combustion exhaust gas even in a temperature range of 150 to 400°C without supplying reducing gas from outside.
It is an object of the present invention to provide a method for producing a molded article for purifying NO and c that stably and effectively removes x.

(Means for Solving the Problems) The present invention uses carbon as a carrier, and the carrier contains an alkali metal element and a transition metal element including elements of groups 1B and 2B of the periodic table (for example, Ni, Fe, Mn%Cu, Zn, Go, Ce, La
, Tb, etc.) and tin, and impregnated with one or more elements from the group consisting of tin.
The cleaning agent contains AQ, O, Sin, Tie, ZrO,
A molded article for exhaust gas purification that uses heat-resistant materials such as , etc. and water glass as a binder, mixes the mixture, compression molds it into a specific shape, flows CO8 gas, or leaves it in the air to react with CO2 and harden. It pertains to the manufacturing method.

The above-mentioned carbon includes graphite, coal, charcoal, fine carbon, or a substance containing carbon as a main component, and activated carbon, which belongs to fine carbon, is particularly preferred.

Moreover, even if these carbons contain as impurities not only the above-mentioned transition metal elements and alkali metal elements, but also alkaline earth metal elements and heat-resistant substances such as AQ, O, SiO, TiO, etc. good.

As a method for impregnating carbon with an alkali metal element, a known method such as a method of immersing carbon in a solution of an alkali carbonate, nitrate, acetate, hydroxide, etc. is employed. Furthermore, when impregnating with Cu, Ni, Fe, Co, Ce, etc., use their acetates and carbonates.

A method of adding carbon to a solution of nitrates, hydroxides, etc. and drying it can also be used. Alternatively, carbon may be added to a solution of alkali ferrocyanide or the like and then dried.

In order to keep pressure loss low, it is desirable to mold the purifier into a honeycomb shape, etc. The ratio of each component for molding should be adjusted to improve No x purification properties, mechanical strength, abrasion resistance, abrasion resistance, heat resistance, etc. are selected in consideration of For NOx purification properties, the proportion of metal-supported carbon is increased, and when heat resistance and mechanical strength are important, the proportion of heat-resistant substances is increased. Another important factor is the carbon particle size.

The particle size of carbon is preferably 250 .mu.m or less; if it exceeds 250 .mu.I, molding becomes difficult and the purification ability decreases.

To improve the No. purification properties, heat treatment at 100° C. or higher in an inert gas, vacuum, or/and an oxygen concentration of 20% or less before use is effective. In addition, if the exhaust gas contains oxidizing gases such as oxygen, the concentration and operating temperature should be taken into account and the purifying agent should be subjected to a mild reaction with oxygen, H, O, etc. or treated with sulfur oxides such as S02 before molding. Alternatively, if the molded product is treated with a mild reaction with oxygen, H, O, etc. or with a sulfur oxide such as SO□ to create a chemically stable oxidized surface, it will have excellent heat resistance and ignition resistance. It can be used to enhance the quality.

(Example-1) NOx was prepared by impregnating commercially available activated carbon with an average particle size of 200 μm with salts of potassium, cerium, and manganese as described above.
A purifying agent with purifying ability was prepared. This purifying agent is made by soaking activated carbon in a CO3 solution and then drying it.
It was manufactured by immersing Ce and Mn in an acetic acid solution and then drying it again in the air.

Hereinafter, such a purifying agent will be referred to as C/Ce/Mn.

100g of this purifying agent, 0.10g of v-Affi, and 5
% water glass aqueous solution of 37 mA, and add this to the first
Fill the molding machine shown in the figure and Fig. 2, and the outer diameter is 30 mm.
It was formed into a honeycomb structure with a porosity of 85% and an apparent volume of 12 mQ, and was left at room temperature.

100 pieces of the honeycomb structured molded body obtained in this way
Heat treatment was performed at ℃ for 2 hours. The molded body was fixed in a quartz tube with an inner diameter of 35 mm, and NO30Oppm, C0,1 was produced at room temperature.
0 volume%, H, 010 volume%, 0°5 volume%, remainder N,
The gas flow rate to the compact after passing through the mixed gas consisting of 20
/min.

Thereafter, the molded product was brought to a predetermined temperature, and changes in NO concentration were measured using a chemiluminescence NOx analyzer to examine the NO purification properties of this purification molded product.

No. 2 also showed similar characteristics. The results are shown in Figure 3.

(Examples-2 to 5) In the same manner as in Example-1, C/Na/Cu/Mn (Example-2), C/Ni/Sn (Example-3), C/Ni/F
e/Zn (Example-4), C/Ni/Th/Ni (Example-5) were prepared, and C/AQ20. and a 5% water glass aqueous solution in the same proportions as in Example-1 to obtain a molded article with a honeycomb structure, and its purification properties were measured under the same conditions as in Example-1. The results are shown in FIG.

When the purification molded article of the present invention is used in a high concentration of oxygen such as air, the amount of supported metal added may be reduced, or the purification molded article may be heated with oxygen or sulfur compounds such as S02 before or after molding. Chemically stabilize the reaction surface to further improve ignition resistance. The molded product after the stabilization treatment can also be activated by heat treatment at 100 to 400° C. in air, at an oxygen concentration of 20% or less, or in an inert gas, so as to meet the usage conditions.

(Effect) The present invention uses carbon as a carrier and an alkali metal element,
A purifying agent that supports one or more transition metal elements including group 1B and 2B elements of the periodic table and tin can remove NO in a dry manner without using NH, etc., and is safer. problem is solved.

In addition, by adding and mixing a heat-resistant substance and water glass to the purifying agent and forming it into a fly cam shape, the pressure loss and heat resistance are reduced to 1.
Mechanical strength and wear resistance are improved6

[Brief explanation of the drawing]

The drawings show one embodiment of the invention. Figure 1 is a plan view of the molding machine, Figure 2 is a longitudinal sectional view of the molding machine,
FIG. 3 is a graph showing the NO purification rate. It is. In the figure: l...pin, 2...push top cover, 3...two-split mold, 4...outer frame mold, 5...mold matching plate,
6...Lower mold with pin.

Claims (1)

[Claims] 1 Carbon is used as a carrier, and the carrier is impregnated with one or more metal elements selected from the group consisting of an alkali metal element, a transition metal element including group 1B and 2B elements of the periodic table, and tin. 1. A method for producing a molded article for exhaust gas purification, which comprises forming a purifying agent, adding and mixing a heat-resistant substance and water glass to the purifying agent, and compression molding the mixture.