JPS5958117A - Exhaust gas controlling catalyzer for internal combustion engine - Google Patents

Abstract

PURPOSE:To maintain the catalytic activity of exhaust gas control for a long period of time, by having one side of either the upstream side end face or the downstream side end face of each through hole closed with a nonpermeable substance and disposing both end faces so as to adjoin with each other, while forming an active alumina layer on the wall surface of a hole whose upstream side end face is opened and also forming a catalytic layer on the wall surface of another hole whose downstream side end face is opened. CONSTITUTION:Auto exhaust flows into a hole 2 whose upstream side end face is opened. Since the hole is closed at its downstream side end face, the exhaust moves to the inside of the hole whose adjoining downstream side end face is opened as flowing down to the hole inside. In time of this movement, the exhaust goes across the porous partition wall of a porous active alumina layer 5 formed on the surface of the partition wall and catches a poisoned substance, contained in the exhaust, on the active alumina layer's surface and inside the layer itself. Those of minute ones escaping from the catch are caught at inside the partition wall. After passing the partition wall, the exhaust crosses a catalytic layer 1 formed on its passing surface whereby noxious components are purified. Thus, the poisoned substance such as a lead compound, phosphide, etc., is removed before it comes in contact with the catalytic layer.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a catalyst for purifying exhaust gas from an internal combustion engine, and particularly to a catalyst in which a catalyst substance is supported on a honeycomb structure carrier made of a porous inorganic sintered body.

A catalyst that purifies harmful components in the exhaust gas of an internal combustion engine by oxidation and/or oxidation reaction is required to have good purification ability and to have excellent durability. However, when the exhaust gas contains poisonous substances such as lead compounds and phosphorus compounds, the viscosity of the catalyst is seriously impaired due to the poisoning of the catalyst material. Techniques for preventing poisoning by lead compounds have had little success in regions and countries where catalysts are not poisoned, even though catalyst durability is a major problem.

Regarding the honeycomb catalyst, 1JI: Regarding the flow of gas particles - Flow 0!0 For a carrier formed with a large number of through holes (cells) parallel to its axis from the end face to the downstream end face, all the through holes (cells) The conventional structure is to support the catalytic material on the walls of the pores. The exhaust gas sweeps over the surface of the catalyst material while flowing down through all the through holes.

In April, the catalyst material was poisoned by poisonous substances at the same time as it was being purified of harmful components.

The present invention overcomes the above-mentioned problems and provides a honeycomb catalyst that can maintain I-catalyst activity for a long period of time without being poisoned by poisonous substances in exhaust gas. ,The porpose is to do.

In order to achieve this object, the present invention has the following configuration. That is, in a carrier having a honeycomb structure made of a porous inorganic sintered body, each through hole has its upstream end ih+
Or, either one of the openings of the downstream end face is blocked with a non-permeable material, and the hole whose downstream end face is closed and the hole whose downstream end face is blocked are adjacent to each other. Placed in [O] Tewari.

In addition, regarding the flow of gas residue, an activated aluminum layer is formed on the wall of the hole whose upstream end face is open, and a catalyst layer is formed on the wall face of the hole whose downstream end face is open. It has a certain configuration.

With this configuration, the exhaust gas is
The water flows into the hole where the FJ is released. The hole is downstream/1
1! Since the l end is closed, the water flows down the hole and moves into the hole that engages the hole, ν1'', that is, the downstream end face is open. During the transfer, first, a porous activated alumina plate formed on the surface of the partition wall forming the inflow hole is then passed across the same porous IVA wall, and at that time, the alumina contained in the exhaust gas is transferred. Toxic substances are trapped between the bags and within the layers of activated alumina. The pL1 thinner ones with captured lPS<1 are captured within the septum. After passing through the partition wall, the exhaust gas from which poisonous substances have been removed crosses a catalyst layer formed on the surface where it has passed twice, and during Jf:, self-harming components are purified.

In this way, after the three 11·(s) are 1'l+1/(laterally 1'l+1/), they flow smoothly into the hole where they have moved and are discharged from the opening on the tidal side 6iAi.

In this way, when using the catalyst of this invention, lead compounds,
Poisoning substances such as phosphorus compounds are removed before contacting the catalyst IN. Therefore, the catalyst material is not poisoned, exhibits its ability to purify harmful components satisfactorily, and the durability of the catalyst is ensured.

In addition, this catalyst has the following effect #5.

In other words, the amount of activated alumina required is almost the same as that of a catalyst with a conventional structure, but the alumina with open pores on the upstream side is intentionally filled with catalyst material so that it can act as a trap for recycled materials. Since it is not supported, a structure for trapping poisonous substances is realized that is simple, reliable, and inexpensive.

Moreover, with this catalyst, υF air scum touches! Since the IM is 10" horizontally, it is extremely efficient in terms of unit h (per unit) of catalyst material compared to conventional honeycomb structured catalysts that sweep across the surface.

Therefore, even if the number of catalyst materials is reduced compared to the conventional structure, the same or better performance can be obtained.

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

Ceramic carrier with honeycomb shape (number of through holes 2
00/in”, bulkhead shore-Q, 3 ms, fine a
t hole OJ diameter = average 257] m, Tanikaze = 11),
The arrangement of the opening of the direct hole and the closed part on the end face is
- Prepared one whose end face of force is opposite to the other end face.

1 and 2 show this, where 1 is the carrier, 11 is the partition wall, 2 is the through hole, and 3 is the through hole 2 on one end surface.
4 indicates a filling portion that closes the opening of , and 4 indicates a filling portion on the other end surface.

Next, 10 fine powders obtained by crushing commercially available activated alumina granular carriers were prepared.
To 0 parts by weight hl', 0 parts by weight of alumina silua, 30 parts by weight of water, and some parts by weight of an aqueous aluminum nitrate solution were added and stirred to prepare an alumina slurry having a viscosity of 2,200 cps. In addition, a commercially available activated alumina granular carrier with a viscosity of "-" 200 cps was obtained using the same process as above, except that a step of immersing it in an aqueous palladium chloride solution and drying it in air at 120°C for 6 hours was added. 1. Prepare a palladium slurry.

Next, after sufficiently absorbing water into the ceramic carrier and blowing off excess water, alumina slurry was injected into the hole opened from the end face of the nigga.

Blow off excess slurry with air and heat in air at 120'C.
It was dried and fired for 1 hour in an electric furnace at 700°C. I let it absorb enough water again and blew off the excess water.''2.
A palladium-containing slurry was injected into the hole opened from the other end face. A predetermined amount of bt was deposited, dried and calcined in the same manner as in Section 2 to obtain a catalyst as shown in FIG. In this figure, 5 indicates an activated alumina layer, and 6 indicates a catalyst layer. Also, arrow S indicates the direction in which the alumina slurry was injected,
Arrow P indicates the direction in which the palladium-containing slurry was injected, and arrow E indicates the direction in which the gas flows.

In addition to this fruit horn iD example, a comparative example was prepared as follows. Commercially available cordierite honeycomb-shaped ceramic carrier (number of through holes = 2007 in”, partition wall thickness =
0.3 wrr, micropore diameter = average 57zm, volume 1
After sufficiently absorbing water to ft=11 and blowing off excess water, the same amount of palladium-containing slurry as in the example was deposited. The same amount here means that the amount of palladium used per ceramic carrier is the same. Next, it was dried and fired in the same manner as in the example.

The structure of this comparative example is, of course, a conventional structure.

In order to confirm the effectiveness of this invention, we constructed an automobile engine with a -1-1 exhaust crucible 2e in which the catalysts of the following two examples and comparative examples were installed in the catalytic converter case in the usual manner. It was connected to the trachea and subjected to bench endurance operation. The operating condition is that the lead content of the fuel is M''' 0.4 g/e.

Rotational speed = 2 (100 rpm, load = 172
, air-fuel ratio = approximately 16. Temperature of tillage gas at catalyst inlet = 400
C1 total operating time = 20 Q hr, and the purification rate of HC and CO was measured every 50 hr of operating time.

Figure 4 shows the measurement results, and shows that the reduction in purification rate as the operating time elapses is large +jJ in the comparative example and is particularly significant in IIC, whereas in the example it is not only slight but gradual. It was confirmed that this invention is extremely effective.

In the embodiments detailed above, palladium was used as the catalyst metal, but other metals can be used according to the purpose of the catalyst in this invention. For example, in the case of automobile υ [for gas purification, platinum B3 metals such as platinum (PT) and rhodium (Rh), copper (Cu), chromium (Cr), ), base metals such as nickel (Ni), and rare earth metals or oxides thereof. Furthermore, a combination of two or more metals or two or more oxides can be used.

Nana I hope you get a similar effect.

[Brief explanation of the drawing]

1 to 3 are enlarged and exaggerated illustrations of the pores of a catalyst according to an embodiment of the present invention; FIG. 1 is a perspective view;
FIG. 2 is a longitudinal sectional view and left and right side views thereof, and FIG. 3 is a partially enlarged view of the longitudinal sectional view. fP, Figure 4 is a graph showing the changes in i4+ (i4+) compared to Example 11. 1: PI! It medium 411 body 2: Through hole (cell) 3, Filling part where 11 old-1 part of the through hole is closed 4: Same 1' 5, Active T'l/Alumina layer 6: Catalyst! - Applicant: I-Yoku Jidosha Co., Ltd. Figure 1 Figure 2 Logic conversion time (hr)

Claims (1)

[Claims] (1) In a honeycomb-structured catalyst carrier made of a porous inorganic sintered body and having a large number of through-holes extending along the axis from the downstream end face to the upstream end with respect to the flow of exhaust gas, each through-hole Either the upstream end face or the downstream end face is closed with a non-permeable substance, and the hole whose upstream end is closed and the hole whose upstream end iu is closed are adjacent to each other. d, and regarding the flow of υtoki scum. An internal combustion engine characterized in that porous activated alumina 1- is formed on the wall surface of the hole whose downstream end surface is open, and a catalyst layer is formed on the wall surface of the hole whose downstream end surface is open. Nori “Catalyst for purifying air scum.