JPS60216819A - Honeycomb filter for collecting particulate and process for preparing the honeycomb filter - Google Patents

Abstract

PURPOSE:To reduce the amt. of catalyst to be supported and to reduce pressure drop by forming a uniform alumina layer on such cells only having an opening at the inlet side of the cells and the catalyst uniformly on said alumina layer. CONSTITUTION:An adhesive agent 5 comprising a combustible substance is packed to the inlet side 3 and the outlet side 4 of the cells 2 of a honeycomb structure body 1 comprising cordierite. The honeycomb structure body is immersed in the slurry 6 to be used for coating gamma-alumina, and then pulled up and dried after removing excess slurry, and then calcined. The cells 2 on which the alumina layer 7 is not formed are plugged at the inlet side 3, and the cells 2 on which the alumina layer 7 is formed are plugged at the outlet side 4, with clay material 8. The honeycomb filter 9 is immersed in a soln. of PdCl3, and reduced, washed with water, dried, and calcined, thus a honeycomb filter having catalyst 10 deposited thereon is prepd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a honeycomb filter used for collecting Denzel particulates such as carbon particles contained in the exhaust gas of a diesel engine, and a method for manufacturing the same.

[Prior art]

Ceramic filters such as foam filters and honeycomb filters have been proposed as filters for collecting diesel particulates such as carbon particles contained in the exhaust gas of diesel engines. Such filters are normally used for a long period of time while being regenerated by periodically burning the captured carbon particles, and various regeneration methods have been proposed.

Methods for regenerating this filter include increasing the exhaust gas temperature by using an intake throttle or an exhaust throttle;
(Method of igniting and propagating combustion using a BL heater, burner, etc.)
(C) A method using a fuel additive, (d) A method of supplying unburned gas into exhaust gas, etc. are known.

Regardless of which of these methods is employed, it is considered desirable to carry a catalyst on the filter to ensure regeneration.

By the way, in the case of foam filters, it is relatively easy to convert them into catalysts due to their structure, but in the case of honeycomb filters, either the inlet side or the outlet side of the cells is always blocked by plugging, etc. However, there is a problem in that catalyticization is extremely difficult. For example, when a filter is immersed in slurry for forming an alumina layer, it is necessary to forcibly push the slurry into the cell so that the filter does not sink, and after the filter is pulled up from the slurry, excess slurry is blown away. This is due to the fact that it is not possible to clean it thoroughly and it is easy to get clogged.

In addition, in the honeycomb filter for particulate collection obtained by the conventional method, a catalyst is also supported in the cells with an open outlet side, which does not require a catalyst. The problem is that the supported catalyst is substantially wasted and the amount of gas sulfate increases.

[Purpose of the invention]

The present invention has been made to solve the problems of the prior art described above, and an object of the present invention is to improve the manufacturing method of a honeycomb filter for particulate collection so that the inlet side is open to exhaust gas. The purpose is to form a uniform alumina layer only in the cells in which the catalyst is present, and to uniformly support the catalyst.

[Structure of the invention]

According to the present invention, the object is to have a columnar shape, and a large number of cells are formed inside thereof from the exhaust gas inlet side to the exhaust gas outlet side, and these cells are arranged on either the exhaust gas inlet side or the exhaust gas outlet side. A honeycomb filter for collecting particulates in which cells are alternately closed, and an alumina layer is provided only in the cells whose exhaust gas inlet side is open, and a catalyst is supported on this alumina layer. This is achieved by a honeycomb filter for collecting particulates, which is characterized by: ------
1. First Invention According to the present invention, the present invention has a columnar shape, and has a large number of cells formed therein from the exhaust gas inlet side to the exhaust gas inlet side. For particulate collection, an alumina layer is provided only in the cells where one of the outlet sides is alternately closed and the exhaust gas inlet side is open, and a catalyst is supported on this alumina layer. A method for manufacturing a honeycomb filter, in which a honeycomb structure with unblocked cells is first prepared, the inlet and outlet sides of the cells on the side that do not support the catalyst are blocked with a combustible substance, and in this state, an alumina slurry is poured into the honeycomb structure. The cell outlet side and the alumina layer were immersed in water, pulled up, dried, and fired to form an alumina layer, and the combustible material was burned and removed, and then an alumina layer was formed using a non-flammable material such as ceramic. This is achieved by a method for manufacturing a honeycomb filter for collecting particulates, which is characterized in that the inlet side of the cells that do not form any particles is closed, the cells are immersed in a catalyst solution in this state, and then pulled out, dried, and fired. -.- Second invention [Effects of the invention] As described above, according to the present invention, the following effects are achieved.

(a) In the particulate-collecting honeycomb filter of the present invention, the catalyst is supported only in the cells that are open on the exhaust gas inlet side, so the amount of catalyst supported can be reduced to about half that of the conventional filter.

(b) In the honeycomb filter for particulate collection of the present invention, since no catalyst is supported in the cells whose exhaust gas exit side is open, the amount of sulfate generated can be reduced accordingly.

(c) In the honeycomb filter for particulate collection of the present invention, the alumina layer is provided only in the cells where the exhaust gas inlet side is open, so the alumina layer is thinner than before. The pressure loss associated with the formation of the layer can be reduced compared to the conventional method.

(d) According to the method for manufacturing a honeycomb filter for collecting particulates of the present invention, it is easy to form an alumina layer, and a uniform alumina layer can be formed. As a result, the catalyst loading distribution becomes uniform, and the activity of the catalyst is improved.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

Here, FIG. 1 is a schematic diagram showing the manufacturing process of a honeycomb filter for collecting particulates according to an embodiment of the present invention, and FIG. 2 is a perspective view of a honeycomb filter for collecting particulates according to an embodiment of the present invention. It is a diagram.

Figure 1 (commercially available diameter 100m5, length 100m shown in al.
A cylindrical cordierite honeycomb structure 1 of fl was prepared, and the cells 2 were alternately plugged on both the inlet side 3 and the outlet side 4 with an adhesive which is a flammable substance. Due to this work, as shown in Figure 1(b), the inlet side 3
A honeycomb structure was obtained which alternately had cells 2 whose both the inlet side 3 and outlet side 4 were plugged, and cells 2 whose inlet side 3 and outlet side 4 were not plugged. Next, as shown in FIG. 1 (C1), this honeycomb structure 1 was immersed for 1 minute in an alumina coating slurry 6 consisting of γ-alumina powder, aluminum nitrate solution, alumina sol, and distilled water. After blowing off slurry 6 with air flow, 12
It was dried at 0°C for 3 hours and fired at 600°C for 2 hours to obtain a honeycomb structure 1 having cells 2 alternately coated with γ-alumina layers 7 as shown in FIG. , cordierite, a clay-like material which is a non-flammable material whose main component is distilled water, is placed in the cell 2 in which the T-alumina layer 7 is not formed.
The cells 2 formed with T-alumina N7 are packed in the inlet side 3 and the cells 2 formed with T-alumina N7 are packed in the outlet side 4, respectively, and fired at 900°C for 3 hours to form the cells 2 as shown in Fig. 1(e). A honeycomb filter 9 in which the inlet side 3 and the outlet side 4 were alternately closed with plugs 8 was obtained. After that, this honeycomb filter 9 is immersed in a palladium chloride solution, and while being rocked up and down,
After holding for a period of time, reducing, washing with water, drying, and firing, the first
As shown in FIG.

Note that the catalyst 10 is originally impregnated with γ-alumina l1i7 and appears to be a single piece, but for convenience of explanation, it is shown in Figure 1 (
In f), γ-alumina ii7 and catalyst 10 are shown separately. The resulting honeycomb filter 9 is shown in FIG. The amount of palladium supported at this time was 1 g per 11 honeycomb filter volumes, and the amount of alumina coated was IJ.
It was 30g per serving.

(Comparative Example 1) A commercially available cylindrical cordierite honeycomb structure with a diameter toot and a length of 100fi was prepared, and on either the inlet side or the outlet side of each cell of this honeycomb structure,
They were alternately filled with clay-like materials whose main component was cordierite. Subsequently, it was fired at 900° C. for 3 hours to obtain a honeycomb filter in which the inlet and outlet sides of the cells were alternately plugged.

Next, this honeycomb filter was immersed for 1 minute in an alumina coating slurry consisting of T-alumina powder, aluminum nitrate solution, alumina sol, and distilled water. After pulling it up and blowing off the excess slurry with an air stream, it was dried at 120°C for 3 hours and fired at 600°C for 2 hours to obtain a honeycomb filter coated with a T-alumina layer. Thereafter, this honeycomb filter was immersed in a palladium chloride solution, held for 1 hour while being rocked up and down, and underwent reduction, water washing, drying, and firing steps to catalyze the honeycomb filter. The amount of palladium supported at this time was 1 g per 11 volumes of the honeycomb filter, and the catalyst was supported in all cells. Further, the amount of alumina coated was 70 g per 11 pieces.

(Comparative Example 2) A commercially available cylindrical cordierite honeycomb structure with a diameter of 100 mm and a length of 100 m was prepared, and as in Comparative Example 1, either the inlet side or the outlet side of each cell of this honeycomb structure was prepared. One of the filters was alternately filled with clay-like materials mainly composed of cordierite and fired at 900° C. for 3 hours to obtain a honeycomb filter in which the inlet and outlet sides of the cells were alternately plugged. Next, a γ-alumina layer was formed on this honeycomb filter in the same manner as in Comparative Example 1. Note that in Comparative Example 2, the honeycomb filter was not catalyzed.

The three types of honeycomb filters thus obtained were evaluated on the following items to confirm their effectiveness.

(Test Example 1) ---Clogging ratio by γ-alumina t - Diameter 1n
The test was carried out by passing a stainless steel rod.

(Test Example 2) --- Sulfate emission suppression effect Each honeycomb filter was attached to the exhaust system of a diesel engine at 2.2, and the engine speed was 2500 rpm.
The system was operated at a temperature of 450° C. for the large gas to the honeycomb filter, and the amount of sulfate contained in the exhaust gas downstream of the honeycomb filter was analyzed one hour after the start of operation.

(Test Example 3) - Evaluation of Particulate Combustion Temperature by a Catalyst Each honeycomb filter was attached to the exhaust system of a 2.21 diesel engine, 200 Orpm, ) Luk 3 kg
Particulates were collected at -m for 5 hours.

Then, increase the rotation speed to 2500 rpm, set the large gas temperature to 400 °C by adjusting the torque, and
The device was operated for 0 minutes and changes in back pressure were recorded. Judgment as to whether or not particulates are combusted by the catalyst is determined based on the back pressure.For example, if the back pressure increases during operation of large gas at 400℃, it is determined that combustion is not possible, and if the back pressure decreases, it is determined that combustion is possible. In this case, the human gas temperature was increased by 25°C for evaluation. Note that since it is difficult to maintain an exhaust gas temperature of 500°C or higher using torque alone, an intake throttle was also used.

(Test Example 4) ---Analysis of catalyst loading distribution Regarding the honeycomb filter for which all the above evaluations have been completed, the attached particulates are burned in an electric furnace, and then the honeycomb filter is cut and each part of the honeycomb filter is The amount of palladium supported was measured. The measurement sites were three points: near the inlet side of the center of the honeycomb filter, the central part, and near the outlet side.

The results of Test Examples 1 to 4 above are shown in Table 1.

Table 1 As is clear from Table 1, the honeycomb filter for particulate collection of this example has better catalyst performance than the conventional honeycomb filter for particulate collection if the amount of catalyst supported is the same. It can be seen that the sulfate content is low, the sulfate content is low, and the alumina coating layer is good.

Although specific embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and includes various embodiments within the scope of the claims. .

[Brief explanation of drawings]

Fig. 1 is a schematic configuration diagram showing the manufacturing process of a honeycomb filter for collecting particulates according to an embodiment of the present invention, and Fig. 2 is a perspective view of a honeycomb filter for collecting particulates according to an embodiment of the present invention. . 1------Honeycomb structure 2---Cell 3---Inlet side 4---One outlet side 5---One stopper (flammable material) 6- ------Alumina coating slurry 7-----γ-
Alumina layer (alumina layer) 8---11---Plug (non-flammable material) 9---Honeycomb filter 10---Catalyst ii! ! l

Claims (1)

[Claims] (11 columns, with a large number of cells formed inside from the exhaust gas inlet side to the outlet side, and these cells are arranged alternately on either the exhaust gas inlet side or the exhaust gas outlet side. Among the cells, an alumina layer is provided only in the cells whose inlet side for exhaust gas is open, and a catalyst is supported on this alumina layer. A honeycomb filter for collecting particulates. (2) It has a columnar shape, and a large number of cells are formed inside from the exhaust gas inlet side to the outlet side. For particulate collection, an alumina layer is provided only in the cells where one of the outlet sides is alternately closed and the exhaust gas inlet side is open, and a catalyst is supported on this alumina layer. A method for manufacturing a honeycomb filter, in which a honeycomb structure in which cells are not blocked is first prepared,
The inlet and outlet sides of the cell on the side that does not support the catalyst are blocked with a flammable substance, and in this state, the cell is immersed in an alumina slurry, pulled out, dried, and fired to form an alumina layer and remove the combustible substance. The cells are removed by combustion, and then the outlet side of the cell with an alumina layer formed using a non-flammable material such as ceramic and the inlet side of the cell without an alumina layer are closed off, and in this state, the catalyst solution is immersed, and then pulled out and dried. A method for manufacturing a honeycomb filter for collecting particulates, the method comprising: firing the honeycomb filter.