WO2019131278A1

WO2019131278A1 - Cleaning agent kit for exhaust gas purification filter, and cleaning method

Info

Publication number: WO2019131278A1
Application number: PCT/JP2018/046342
Authority: WO
Inventors: 青木　哲也
Original assignee: 栗田工業株式会社
Priority date: 2017-12-27
Filing date: 2018-12-17
Publication date: 2019-07-04
Also published as: JP6583401B2; JP2019116564A; TW201930578A

Abstract

A cleaning agent kit for an exhaust gas purification filter, the cleaning agent kit containing: an agent A, which contains 5-50% by mass of a chelating agent and 0.1-10 parts by mass of a carbonate and/or a bicarbonate per part by mass of chelating agent; and an agent B, which contains 1-10% by mass of a non-ionic surfactant and/or an anionic surfactant. A method for cleaning an exhaust gas purification filter in which the kit is used.

Description

Cleaning agent kit for exhaust gas purification filter and cleaning method

The present invention relates to a cleaning agent kit used for cleaning an exhaust gas purification filter of a car or the like, and a method for cleaning an exhaust gas purification filter using the cleaning agent kit.

As an exhaust gas purification filter for removing graphite, particulate (PM) and other particulate matter from exhaust gas from internal combustion engines etc., porous (eg honeycomb structure) ceramic sintered body or metal sintered body, wire mesh etc. is used It is done. In addition, it is carried out that an exhaust gas purification catalyst (for example, a platinum-based metal catalyst) is supported on a filter.

When such an exhaust gas purification filter is used for exhaust gas purification, the particulate matter adheres and becomes blocked. Therefore, the filter is removed from the exhaust gas purification device and cleaned periodically or as necessary. ing.

As a method for cleaning such an exhaust gas purification filter, Patent Document 1 describes that the filter is cleaned with high-pressure steam, but the cleaning effect is low with steam alone. Also, the steam injection may damage the filter.

Patent Document 2 describes a method of immersing an exhaust gas purification filter in an alkaline sodium silicate solution and then immersing the filter in a hydrogen peroxide solution for cleaning. In this method, the filter base material made of a ceramic sintered body or the like may be corroded by the alkaline solution or the hydrogen peroxide solution to be deteriorated.

Patent Document 3 describes a cleaning method in which an exhaust gas purification filter made of cordierite-based porous ceramic is immersed in a 5 wt% aqueous solution of EDTA.2Na (disodium ethylenediaminetetraacetate) for 60 minutes, then washed with water and dried. ing. In addition, Patent Document 3 describes that the filter is similarly cleaned using an aqueous solution of a strong acid such as 10 wt% hydrochloric acid or 10 wt% nitric acid, but when the filter is washed with such strong acid, the filter is significantly degraded. easy.

JP, 2011-202636, A JP, 2006-110451, A JP 2004-270688 A

An object of the present invention is to provide a cleaning agent kit and a cleaning method of an exhaust gas purification filter, which can sufficiently restore filter performance without deteriorating the filter, and the cleaning environment becomes good.

The cleaning agent kit of the exhaust gas purification filter of the present invention comprises a chelating agent, an agent A containing 0.1 to 10 parts by mass of a carbonate and / or a bicarbonate per 1 part by mass of the chelating agent, and nonionicity And B agent containing surfactant and / or anionic surfactant.

In one aspect of the present invention, the agent A is an aqueous solution having a concentration of the chelating agent of 5 to 50% by mass.

In one aspect of the invention, the chelating agent is methylglycinediacetic acid or a salt thereof (eg sodium or potassium salt).

In one aspect of the present invention, the carbonate and / or bicarbonate is a sodium or potassium salt.

In one aspect of the present invention, the agent B is an aqueous solution containing 1 to 10% by mass of the surfactant.

The method for cleaning an exhaust gas purification filter of the present invention is a method for cleaning an exhaust gas purification filter using an aqueous solution of the cleaning agent kit of the present invention. Preferably, 1 part by mass of the agent A consisting of an aqueous solution of 5 to 50% by mass of the chelating agent and 0.1 to 10 parts by mass of the agent B consisting of an aqueous solution of 1 to 10% by mass of the surfactant The exhaust gas purification filter is cleaned using a mixture of

According to the present invention, the filter can be thoroughly cleaned to fully restore the filter performance.

In the present invention, since a strong acid (pH 2 or less) or a strong alkali (pH 10 or more) is not used, the filter is not deteriorated by washing. In addition, carbon-based deposits and inorganic-based deposits, as well as urea-based compounds such as cyanuric acid produced by a system to which urea is added can be washed and removed in the same step, so the cost due to the reduction of work processes It is possible to go down.

In the present invention, since the benzene-phenol type solvent is not used, the washing operation environment is good.

FIG. 1 is a graph showing the results of Examples and Comparative Examples. FIG. 2 is a graph showing the results of Examples and Comparative Examples. FIG. 3 is a block diagram of the cleaning apparatus. FIG. 4 is a block diagram of the cleaning apparatus.

The cleaning kit for an exhaust gas purification filter of the present invention comprises agent A and agent B. The agent A contains a chelating agent and 0.1 to 10 parts by mass, preferably 0.5 to 5 parts by mass of a carbonate and / or a bicarbonate, based on 1 part by mass of the chelating agent. The agent B contains a nonionic surfactant and / or an anionic surfactant.

As a chelating agent in the agent A, methylglycinediacetic acid (hereinafter sometimes referred to as MGDA) or a salt thereof is suitable. As a salt of methylglycinediacetic acid, sodium salt or potassium salt is suitable. As carbonates and hydrogencarbonates in the agent A, sodium salts or potassium salts, that is, sodium carbonate, potassium carbonate, sodium hydrogencarbonate or potassium hydrogencarbonate are preferable.

The agent A may contain only the above-mentioned chelating agent and carbonate and / or bicarbonate in the above ratio, and may further contain other components. As other components, pH adjusters, buffers and the like are exemplified. As the pH adjuster, inorganic acids such as hydrochloric acid, sulfuric acid, boric acid and phosphoric acid, organic acids such as citric acid, acetic acid and malic acid, and alkali hydroxides such as sodium hydroxide and potassium hydroxide are preferably used. As the buffer, it is sufficient to maintain the pH of the solution at 6.0 or more, and examples thereof include citric acid, phosphoric acid or boric acid sodium salt, potassium salt, ammonium salt and the like whose pH is 6.0 or more.

The agent A is preferably an aqueous solution having a concentration of the above-mentioned chelating agent of 5 to 50% by mass, preferably 10 to 25% by mass. However, the agent A may be in the form of powder, granules, solid such as tablets. When in solid form, the user dissolves in water at the time of use to prepare an aqueous solution of a predetermined concentration.

As surfactant which comprises B agent, one or both of nonionic surfactant and anionic surfactant are used. Examples of suitable nonionic surfactants include polyoxyalkylene alkyl ethers, glycerin fatty acid esters, sorbitan fatty acid esters, polyethylene glycol fatty acid esters, polyoxyethylene sorbitan fatty acid esters, fatty acid alkanolamides and the like. Examples of suitable anionic surfactants include fatty acid monocarboxylates, alkyl benzene sulfonates, alkyl sulfates, sulfosuccinic acid dialkyl esters and the like.

The agent B is preferably an aqueous solution of such a surfactant, and its concentration is preferably about 1 to 10% by mass, particularly about 2.5 to 7.5% by mass. However, the agent B may be solid, in which case the user dissolves in water at the time of use to prepare an aqueous solution of a predetermined concentration.

The exhaust gas purification filter to be cleaned using the cleaning kit of the present invention is preferably an exhaust gas purification filter for an internal combustion engine, particularly a diesel engine. The exhaust gas purification filter may be any of a honeycomb-like porous ceramic sintered body or a metal sintered body, a wire mesh and the like, but a honeycomb-like ceramic sintered body or a metal sintered body is preferable.

In order to clean the exhaust gas purification filter using the cleaning agent kit of the present invention, the exhaust gas purification filter is brought into contact with a cleaning liquid composed of an aqueous solution containing agent A and agent B.

The concentration of the chelating agent in the washing solution is preferably 0.5 to 5% by mass, particularly preferably 0.8 to 3% by mass. Further, the concentration of the surfactant in the cleaning solution is preferably 0.25 to 2.5% by mass, particularly preferably 0.5 to 2.0% by mass. The pH of this washing solution is preferably 6 to 10, and more preferably 8 to 10.

The water temperature of the cleaning solution at the time of cleaning is preferably about 15 to 50.degree.

In order to bring the cleaning solution and the exhaust gas purification filter into contact with each other, the exhaust gas purification filter may be immersed in the cleaning solution, but it is preferable to use a cleaning device for circulating the cleaning solution to the exhaust gas purification filter.

An example of such a cleaning apparatus is shown in FIGS. 3 and 4.

In FIG. 3, the cleaning liquid in the tank 1 is supplied to the cleaning canister 5 through the valve 2, the pump 3, and the pipe 4. An exhaust gas purification filter F is disposed in the cleaning canister 5. A gap between the outer peripheral surface of the exhaust gas purification filter F and the inner peripheral surface of the cleaning canister 5 is sealed by a packing or the like so that the cleaning solution does not flow in a short circuit manner. The cleaning fluid that has passed through the exhaust gas purification filter F flows out from the cleaning canister 5 to the pipe 6, is introduced into the filter 8 through the valve 7, is filtered, and is returned to the tank 1.

The tank 1 is provided with a heater 1 h for cleaning liquid. The heater 1 h preferably uses steam, hot water or the like as a heat source, but may be an electric heater or a heat pump.

A bypass pipe 9 for bypassing the cleaning canister 5 is provided so that the amount of water flowing into the cleaning canister 5 and the water pressure can be adjusted.

Although the pump 3 is installed outside the tank 1 in FIG. 3, the pump 3 may be a submersible pump as shown in FIG. In FIG. 3, the wash canister 5 and the filter 8 are disposed at the top in the tank 1.

The cleaning canister 5 may be provided with an ultrasonic oscillator. The cleaning solution may be configured to contain microbubbles and nanobubbles. In order to prevent accumulation of air in the cleaning canister 5, it is preferable that the cleaning canister 5 be configured to allow the cleaning solution to flow upward. The tank and piping material is preferably hard polyvinyl chloride that can withstand 60 ° C. In the case of FIG. 4, there is no problem if the filter is immersed in the cleaning solution.

When the exhaust gas purification filter F is cleaned using such a cleaning device, the water flow rate to the exhaust gas purification filter F is preferably 600 L / h or more, but is not limited thereto. It is desirable to check the pressure over time with a pressure gauge, adjust the flow rate if the pressure in the catalyst line tends to decrease, and ensure a sufficient flow rate and pressure on the catalyst side constantly.

Examples of the filter material of the filter 8 include fibers of sand, long hair, cotton and the like, but are not limited thereto.

When the exhaust gas purification filter F is cleaned using this cleaning apparatus, the water temperature is preferably 15 to 50 ° C., and the cleaning time is preferably 10 minutes to 24 hours, and particularly preferably 6 to 24 hours. After washing with a washing solution, it is preferable to rinse with clean water and then to dry.

Example 1
Using the cleaning apparatus shown in FIG. 3, the exhaust gas purification filter was cleaned using agent A (aqueous solution) and agent B (aqueous solution) having the following concentrations.

<A agent>
Potassium carbonate 6 mass%
Potassium hydrogen carbonate 7 mass%
Citric acid (monohydrate) 4% by mass
Methyl glycine diacetate trisodium 17 mass%
<B agent>
Sodium tripolyphosphate 0.75 mass%
Aliphatic alcohol alkoxylate 5% by mass
Sodium alkyl (C6-20) benzene sulfonate 0.3% by mass

A mixed solution in which the agent A (aqueous solution) and the agent B (aqueous solution) were mixed at a volume ratio of 1: 1 was used as a cleaning liquid. The water temperature was 25 ° C. on average.

The exhaust gas purification filters to be cleaned are those (72 pieces) taken from a diesel vehicle that has actually traveled. The travel distance of each vehicle is 30,000 to 1,500,000 kilometers.

The washing time was 6 h, and the water flow rate to the exhaust gas purification filter at the time of washing was 600 L / h or more.

After washing, it was washed with water and dried. The air flow differential pressure was measured for the exhaust gas purification filter before and after the washing, and the blocking rate, the improvement rate and the recovery rate were calculated according to the following equations (1) to (3). The results are shown in FIG. 1 and FIG. FIG. 1 shows the relationship between the blocking rate and the improvement rate, and FIG. 2 shows the relationship between the blocking rate and the recovery rate.

Occlusion rate (%) = differential pressure before cleaning / reference differential pressure (1)
Improvement rate (%) = (differential pressure before cleaning-differential pressure after cleaning) / standard differential pressure × 100 (2)
Recovery rate (%) = (Differential pressure before washing-Differential pressure after washing) / Differential pressure before washing × 100 (3)
The reference differential pressure of the equations (1) and (2) is the upper limit value of the allowable air flow pressure specified by the automobile manufacturer for the exhaust gas purification filter.

Comparative Example 1
A commercial product (trade name DIESEL ISC, active ingredients propylene carbonate, naphthalene, cyclohexane and 1,2,4-trimethylbenzene) was used as the cleaning liquid to clean the 14 exhaust gas purification filters taken out from the actual running diesel vehicle.

About 1 kg of washing | cleaning liquid was apply | coated with respect to the exhaust gas purification filter, and it wash | cleaned, after leaving it to stand for 1 hour or more. Thereafter, an average of 10 minutes of steam was sprayed for an average of 5 times, then hot water was poured over, and then it was naturally dried.

The results are shown in FIGS.

Comparative Example 2
Steam was sprayed on the exhaust gas purification filter taken from a real driving diesel vehicle from various directions for 15 minutes or more, and then high pressure water was sprayed. After that, hot water was poured and allowed to dry naturally. The results are shown in FIGS.

As shown in FIGS. 1 and 2, the average improvement rate of Example 1 is 72%, whereas that of Comparative Example 1 is 25% and Comparative Example 2 is 14%. Further, while the average recovery rate was 63% in Example 1, it was 29% in Comparative Example 1 and 14% in Comparative Example 2.

[Example 2, Comparative Examples 3 to 5] Erosivity Test of Catalyst Carrier by Various Cleaning Agents DPR catalyst taken out from a real diesel vehicle is washed using various cleaning agents, and Al (aluminum) in the cleaning solution after the cleaning The concentration was used to evaluate the erodibility of the catalyst support.

In Comparative Example 3, the cleaning solution is alkaline, contains NaOH at a concentration shown in Table 1, and further contains a nonionic surfactant or an anionic surfactant at a concentration of 1% or less and 0.1% or more. It was added so as to become.

In Comparative Example 4, the cleaning solution is an acid, contains HCl at a concentration shown in Table 1, and the concentration of nonionic surfactant or anionic surfactant in the cleaning solution is 1% or less and 0.1% or more. It is further added with an iron corrosion inhibitor (Asahi Chemical Industry Co., Ltd .: IBIT 500A) so as to be 0.4% or less and 0.1% or more.

In the comparative example 5, after each alkali washing using the said each washing | cleaning liquid (The density | concentration is as Table 1), it washed with water and acid-washed.

In Example 2, the liquid which mixed A agent (aqueous solution) and B agent (aqueous solution) of Example 1 in the ratio of Table 1 was made into the washing | cleaning liquid (a surfactant and the anticorrosive for iron are not included). In Table 1, 20/20 indicates that 20% of agent A and 20% of agent B were added. The same applies to 15/15 /, 10/10 and 5/5.

The DPR catalyst was attached to the cleaning apparatus shown in FIG. 3, and the cleaning solution was circulated and cleaned. The amount of washing solution was about 10 times the catalyst volume. The liquid temperature was 45 ± 5 ° C. in the case of alkali washing, and 25 ± 5 ° C. in the case of acid washing, and was 45 ± 5 ° C. in the example. The cleaning solution was circulated and circulated for the time shown in Table 1 while judging the decreasing tendency of the water flow pressure to the catalyst, the contamination condition of the filter medium of the filter, the flow rate change of circulating water and the appearance of the cleaning solution.

After circulating and washing, the catalyst was taken out, washed with tap water and high-pressure water washing, forced drying was carried out, and after drying, washing was finished.

The Al concentration of the cleaning solution after cleaning was measured according to JIS-K-0102, 58.4. The test results are shown in Table 1.

Moreover, the cleaning effect was evaluated according to the following evaluation criteria based on the external appearance observation result of a filter after completion | finish of washing | cleaning and drying, and a differential pressure improvement rate. The results are shown in Table 1.

<Evaluation criteria>
○: (a) In appearance, the deposit is clearly removed (both the front surface and the back surface are reliably removed). (B) The differential pressure improvement rate is 60% or more.
Δ: Only one of the above (a) and (b) is achieved.
X: Neither of the above (a) and (b) is achieved.

As shown in Table 1, in the washing method of Comparative Examples 3 to 5 using one or both of NaOH and HCl, a large amount of Al is eluted from the catalyst carrier, whereas in Example 2, the Al elution amount is 2 of the lower detection limit. It was found that the catalyst support was not deteriorated at all or hardly by the washing. In addition, Example 2 has a better cleaning effect than Comparative Examples 3 to 5.

Although the invention has been described in detail with particular embodiments, it will be apparent to those skilled in the art that various modifications can be made without departing from the spirit and scope of the invention.
This application is based on Japanese Patent Application No. 2017-251629 filed on Dec. 27, 2017, which is incorporated by reference in its entirety.

1 tank 5 washing canister

Claims

A agent comprising a chelating agent and 0.1 to 10 parts by mass of a carbonate and / or a bicarbonate per 1 part by mass of the chelating agent;
A cleaning agent kit for an exhaust gas purification filter, comprising a nonionic surfactant and / or an agent B containing an anionic surfactant.
The exhaust gas purification filter cleaner kit according to claim 1, wherein the chelating agent is methylglycinediacetic acid or a salt thereof.
The exhaust gas purification filter cleaner kit according to claim 2, wherein the salt of methylglycinediacetic acid is a sodium salt or a potassium salt.
The exhaust gas purification filter cleaner kit according to any one of claims 1 to 3, wherein the carbonate and / or bicarbonate is a sodium salt or a potassium salt.
The agent according to any one of claims 1 to 4, wherein the agent A is an aqueous solution containing 5 to 50% by mass of the chelating agent,
The cleaning agent kit for an exhaust gas purification filter, wherein the agent B is an aqueous solution containing 1 to 10% by mass of the nonionic surfactant and / or the anionic surfactant.
A method of cleaning an exhaust gas purification filter using the cleaning agent kit according to any one of claims 1 to 5.
A method for cleaning an exhaust gas purification filter using the cleaning agent kit according to claim 5, wherein the agent A and the agent B have a ratio of 0.1 to 10 parts by mass of the agent B to 1 part by mass of the agent A. A method of cleaning an exhaust gas purification filter, comprising: cleaning the exhaust gas purification filter using the mixed solution of