JPS63162014A - Exhaust gas filter - Google Patents

Abstract

PURPOSE:To obtain the title exhaust gas filter capable of smoothly burning soot, by depositing specified synthetic zeolite on a structure consisting of a porous ceramic having plural cells alternately provided with closed parts at their ends. CONSTITUTION:A material obtained by adsorbing a metal halide such as CuCl2 on synthetic zeolite is deposited on the exhaust gas filter 1 wherein the inlet-side closed part 4 and the outlet-side closed part 5 are alternately formed on the ends of the honeycomb cells 2 consisting of the porous ceramic produced by the conventional method, and the obtained filter is used as the exhaust gas filter. As a result, the metal halide is stably present and used as the combustion improver for soot, the amt. of soot is reduced, and the soot can be burned without melting the inside of the filter.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention collects particulate matter (hereinafter referred to as soot) emitted from, for example, a diesel engine, and burns the collected soot to remove air from the diesel engine. This invention relates to a diesel exhaust gas filter that aims to reduce the amount of soot emitted into the air.

Conventional technology Diesel exhaust gas filters that collect soot emitted from diesel engines include filters using metal wire mesh coated with alumina, porous structure and ceramic foam filters using foaming agents, and honeycomb-shaped filters. Ceramic monolith filters have been devised. Among them, honeycomb-shaped ceramic monolith filters, which have a soot collection efficiency of 90% or more and have low pressure loss in exhaust gas through the filter, are considered promising as filters for removing soot from exhaust gas.

A diesel exhaust gas filter made of a ceramic monolith filter has a honeycomb structure made of a large number of cells formed by extrusion molding using cordierite as a main component. The ends of this honeycomb structure are alternately closed with approximately 109 lengths of very low porosity material such as cement. These upstream and downstream blockages divide the cell into an inlet and an outlet exhaust gas passage, and almost all of the soot in the exhaust gas is collected on the cell walls. When the engine is operated, soot gradually accumulates, increasing the pressure loss of the exhaust gas at the diesel exhaust gas filter, leading to a decrease in engine performance. Therefore, in order to maintain good engine performance, a method is used to regenerate the diesel exhaust gas filter by burning the soot once a certain amount of soot has accumulated.

Therefore, a diesel exhaust gas filter is desired that can smoothly burn soot and allow the filter to be easily regenerated any number of times.

Problems that the invention aims to solve The soot deposited on the diesel exhaust gas filter is ignited by sparks in the exhaust gas or the ignition heater at the inlet end, combustion spreads at the inlet end, and at the same time, it burns downstream within the cell. do. The soot deposited at this time is soot that is formed due to lack of oxygen at high temperatures, and the main component is carbon.
The temperature of the exhaust gas and the oxygen concentration at that time also vary depending on the operating conditions, but the temperature ranges from 150"C to 4oO°C and the oxygen concentration ranges from 10% to 17%. Therefore, once ignited soot under these conditions will burn. It is difficult to continue to do so, and as a result, the amount of soot deposited increases, and as a result, when combustion starts in that state, the temperature rises too much and the inside of the diesel exhaust gas filter melts. Therefore, in order to solve these problems, a method has been adopted in which a combustion improver is mixed into the fuel.

Although this method differs depending on the type of combustion improver, the combustion temperature is 100 to 250 times lower than when no combustion improver is added.
°C can also be lowered. Therefore, it has the characteristic of being able to continue burning even with a small amount of soot deposited. However, this method has the problem that while the soot burns, the additive gradually accumulates in the form of oxides in the trap. Compounds such as copper, zinc, manganese, and cerium are generally used as additives, and there is no way to discharge accumulated oxides from the trap, resulting in increased exhaust pressure drop. There was a problem that engine efficiency was reduced. Furthermore, in order to mix these additives into fuel, there is a problem in that either a mixed fuel must be prepared in advance or a mixing device must be installed in the vehicle.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide an exhaust gas filter that can smoothly burn soot.

Means for Solving the Problems In order to achieve the above objects, the present invention provides a composite structure in which a metal halide is adsorbed onto a porous ceramic structure having a plurality of cells with alternately closed ends. It supports zeolite.

Effect: Due to the above structure, these metal halide compounds exist stably and act as a combustion aid for soot, reducing the amount of soot.
Moreover, combustion can be performed without dissolving the inside of the filter.

Embodiment An embodiment of the present invention is shown in the figure. 1 is a diesel exhaust gas filter, which is manufactured by the following method, for example.

30 parts by weight of alumina fibers cut to 20 nm or less and 16 parts by weight of ceramic raw material powder are suspended in 3000 parts by weight of water, and after adding an organic binder such as polyvinyl acetate to this mixed slurry, polyacrylamide etc. The mixture was agglomerated using a flocculant, and then made into a sheet using a fourdrinier paper machine. A corrugated sheet was created by bonding a corrugated sheet and a flat sheet using the same method as for manufacturing corrugated board, and this was then glued and wrapped around the core to create a honeycomb shape. . Next, in order that the exhaust gas that has entered one cell 2 passes through the cell wall 3, transfers to the other cell, and is then discharged, the materials described below are applied to each cell alternately at both ends of the no-nicum. By injecting the gas in small quantities, an inlet side and an outlet side closed part 4.6 were formed, and the inlet and outlet exhaust gas passages were divided into an inlet and an outlet exhaust gas passage 7.8. This molded product was fired in the air at 126°C to convert the ceramic fibers, ceramic, and ink raw material powder into ceramics, thereby obtaining the diesel exhaust gas filter 1 as a nonicum structure.Here,
The materials forming the inlet and outlet closures 4.5 are:
2 parts by weight of inorganic material obtained by calcining and pulverizing the sheet and 0 starch
．． Add 1 part by weight and 3 parts by weight to form a paste,
0.1 part by weight of an organic powder is added in powder form and mixed by stirring.

Next, 13 people from Molecular Sheep (fine powder, average particle size 1
0μ or less), 10% (weight ratio) of CuCl2 was adsorbed. This was made by dissolving Cu(J,, ) in ethyl alcohol and then raising the temperature to evaporate the alcohol. Molecular Sheep 13A, which had 10% of this CutJ2 adsorbed, was dispersed in water together with an active surfactant. Sometimes the concentration of Molecular Sheep 13A is 10% in water.
It was a mixed liquid with a weight ratio of Furthermore, a small amount of colloidal silica solution (40% solution) was added as a binder.

In this solution, the trap 1 prepared earlier was wash coated by the dip method to form a synthetic zeolite layer adsorbing metal halide 6, and then dried at 500'C for 2 hours to complete the layer.

The diesel exhaust gas filter obtained in this way is
A regeneration test was performed by attaching it to the engine's exhaust manifold. After operating the engine for 3 hours at 124°rpm, 11m, and 12 kq 11 m of soot, the engine was placed in an idle link state and ignited using the ignition heater for regeneration. Combustion ended in about 3 minutes.
There was hardly any soot left. Perform the above playback test 10 times.
After repeating this process several times, the exhaust gas filter was taken out, cut, and observed, but no cracks, melting, or peeling parts were found anywhere.

A similar experiment was conducted using a conventional exhaust gas filter, and 3
During hourly operation, when the ignition heater was ignited at the same time as the engine was put into the idle link state, the area around the ignition heater burned a little, but the rest did not burn.

Therefore, the machine was returned to its previous state and operated for 3 hours, but the results were the same. When the same process was performed after driving for another 3 hours, rapid combustion occurred and the fuel was regenerated in about 5 minutes. However, after regeneration, soot leakage was observed from some exhaust gas outlet cells. When the above-mentioned regeneration was repeated, soot leaked from about half of the exhaust gas outlet cell section at about the 6th time, and it was found that it was not actually functioning as a filter.

As described above, the present invention is characterized by the use of metal halide compounds such as CuC42, Curl, MnCd2
Metal chlorides such as ZnCl2.00043, fluorides such as CuF2, and iodides such as CuI are adsorbed onto synthetic zeolites such as Molecular Sheep 4M, Molecular Sheep 13X, etc., and supported on a product produced by a conventional method.

In the case of metal halide compounds such as CuCd2, when mixed with soot and combusted, the combustion temperature of the soot will be approximately 20Q ~
It has been well known for a long time that the temperature can be reduced by 250'C and combustion can be carried out at around 400°C. When CuCl2 is supported solely on a cordierite-based ceramic porous body or a mullite-based ceramic porous body, first, it has a small specific surface area, so it does not work well as a combustion aid. Initially, the soot acts as a combustion aid, but at that time, the soot becomes carbon dioxide gas and water vapor and is released outside the trap.
2 remains in Sitraub as CuO. At this time, the CuO is removed from the place where it is supported, making it difficult to use it as a combustion aid in the future. Furthermore, when comparing CuCl2 and CuO, in the case of CutJ, the reduction in the combustion temperature of soot is 200 to 250'C, but in the case of CuO, it is ~100°C, making the effect smaller. At this time, when Cue/2 is adsorbed onto the synthetic zeolite of the present invention, it is extremely stable even when heated. For example, when Curl2 is heated in air, it begins to decompose at around 450°C, and at 75°C.
At around 0°C, all chlorine is released and it becomes CuOO form. However, when adsorbed on synthetic zeolite, approximately SOO°C
It was stable until then, and no decomposition of chlorine was observed. this is,
This is thought to be because it is strongly adsorbed by metal cations such as Na+ in the zeolite lattice, and it is particularly stable when adsorbed to sodium type synthetic zeolite, such as Mu type or X type, among synthetic zeolites. The present invention allows these synthetic zeolites to adsorb metal halide compounds,
It is carried on an exhaust gas filter manufactured by a conventional method and used as an exhaust gas filter.The soot trapped in the exhaust gas filter can be combusted at a low temperature by the auxiliary combustion effect of Curl2, and the carbon
Because uCl2 always exists stably as it is due to the action of synthetic zeolite, it can be used repeatedly, and its combustion-assisting effect does not deteriorate.

In addition, since these are wash coated onto the exhaust gas filter used in the conventional method, the specific surface area inside the filter increases and C
uCl2 can also exhibit a more effective auxiliary combustion effect.

Effects of the Invention The present invention provides a suitable amount of soot by wash-coating a synthetic zeolite adsorbed with a metal halide compound on an exhaust gas filter formed by alternately closing the cell ends of a honeycomb structure made of porous ceramic. If soot is deposited and ignited with a heater, most of the deposited soot will burn, and unlike conventional methods, it will not continue to burn unless a considerable amount of soot accumulates, and once it starts burning in that state, it will cause the temperature inside the filter to rise. There is no need to worry about soot leaking due to internal melting, or the trouble of mixing additives into the fuel, and these additives can be used fairly easily without causing engine troubles due to increased pressure drop in the filter scale. It provides a shrinking filter.

[Brief explanation of the drawing]

The figure is a partial sectional view of an exhaust gas filter according to an embodiment of the present invention. 1... Exhaust gas filter, 2... Senope 3
-----=Cell wall, 4.6... Entrance, outlet side closing part, 6... Synthetic deolite layer part adsorbing metal rogenide compound, 7.8... ...Inlet, outlet exhaust gas passage, 9...Soot.

Claims (2)

[Claims] (1) An exhaust gas filter in which a synthetic zeolite adsorbed with a metal halide is supported on a porous ceramic structure having a plurality of cells with alternately closed ends. (2) The exhaust gas filter according to claim 1, wherein the synthetic zeolite is an A-type or X-type sodium type synthetic zeolite.