DE1271462B - Process for the catalytic oxidation of internal combustion engine exhaust gases - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY GERMAN ^ gTV ^ PATENT OFFICE

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German class: 46 c6-6 / 02

1 271462
P 12 71 462.4-43
3rd November 1961
June 27, 1968

The invention relates to a method for the catalytic oxidation of internal combustion engine exhaust gases by successively passing the exhaust gases through two one behind the other in the direction of flow arranged catalyst layers.

Such a method is already known in which two are located one behind the other in the direction of flow Filter layers of catalyst grains are arranged, the grain size of which increases in the direction of flow. In addition, the cross section of the filter layers increases in the direction of flow. Such procedures are used for exhaust gas purification by catalytic means to remove hydrocarbons, oxygen-containing organic Compounds, carbon monoxide or the like. From the exhaust gases of internal combustion engines, in particular from gasoline-powered engines. Especially with fuels containing lead the effectiveness of the catalytic converters decreases significantly over the course of the period of use. This decrease is very strong, especially in the low temperature range, so that it is not practically possible is to quickly reach the desired operating temperature when starting the engine.

The invention is based on the object of simplifying the productivity of such a method Way to improve. There should not be any particularly complex devices for implementation such procedures may be required. The effectiveness of the catalytic oxidation of the exhaust gases should in particular in lead-containing fuels can be increased without affecting the service life of the Catalyst materials used is reduced.

The invention consists in that the catalyst layer exposed to the exhaust gases first consists of such Catalyst grains an average grain size between about 0.075 and 0.135 cm thereafter is reused in the second catalyst layer.

It is known, in the case of exhaust gas cleaning processes, that those arranged next to one another in the direction of flow Single filter, d. H. the individual filters arranged side by side in groups in the direction of flow, to be replaced, as the flow through the individual filters in the middle of the filter group is greater is than the individual filters arranged at the edge of the filter group. There, however, should only a fairly even consumption of the catalyst grains take place, but not the above-mentioned Task to be solved.

The invention makes it possible that the disadvantages of the previously known methods of the above-procedural methods for the catalytic oxidation of
Internal combustion engine exhaust

Applicant:
Oxy-Catalyst, Inc.,
Berwyn, Pa. (V. St. A.)

Representative:

Dipl.-Ing. Dr.-Ing. R. Poschenrieder,

Patent attorney,

8000 Munich 8, Lucile-Grahn-Str. 38

Named as inventor:
Eugene Jules Houdry,
Ardmore, Pa. (V. St. A.)

named genus can be avoided. The effect of oxidation catalysts for internal combustion engines can according to the invention in the range of the low even with prolonged use Tempering temperatures can be extended. An extremely efficient process is achieved, and it is possible, despite good exhaust gas cleaning, to use the catalytic converters in a relatively large operating temperature range, which are relatively expensive to be practically fully exploited.

Since fresh catalysts are practically always available in the first catalyst layer, through which the engine exhaust gases first pass, which are also highly effective in relatively low temperature ranges between about 290 and 400 ° C, the method according to the invention is used for exhaust gas purification in practically all of the areas in question operating temperature range, since the second catalyst layer, which is characterized by long life, especially at temperatures between 480 and 73O ⁰ C, ie sufficient time after starting, stands for the normal functioning of the internal combustion machines. The normal operating temperature range of the exhaust gas cleaner can therefore be reached quickly, so that an overall better overall effect is achieved on average.

809 567/461

According to a further embodiment of the invention, it is particularly useful that the reuse catalyst grains of the first catalyst layer used from about 3000 to 19000 kilometers takes place in the second catalyst layer and this there between about 18,000 to 29,000 Travel kilometers remain if it is an internal combustion engine vehicle. Be there about 8 to 66% of the total weight amount of catalyst is used in the first catalyst layer.

Surprisingly, it was found that the reuse of the catalyst in the second Catalyst layer enables the catalyst to be used for a much longer period of time than before

downward movement and the rib 18, the lowermost grid 24 against downward movement.

According to FIG. 2 to 4 sections 36 are punched out in each grid 24 along the sides thereof Form slots 38 and 40 for the passage of the exhaust gases. From Fig. 1 it can be seen that the uppermost grid 24, the sections 36 extend downwards, while the other two grids 24 the sections 36 extend upward.

ο According to Fig. 1, the housing 2 has a storage container serving end portion 44, with flanges 46 and 48 for the sliding support of the uppermost grid 24 is provided so that it can expand and contract. The front

was the case. The catalytic converter can therefore be divided into two separate compartments be used moderately long before it is discarded, a wall 50 divides the two at its lower end the must. This results in a significant reduction in the cost of the catalyst. This affects be

especially with exhaust gas cleaners that are used for

Has flanges 52 and 54 which form a slot as a support for the central grid 24, so that this can expand and contract.

witnesses to be used. The reservoir 44 is also flanged 56

On the basis of the in FIG. 1 to 7 shown exhaust and 58 provided, which has a slot for a sliding

cleaner, the invention is explained in more detail below. The exhaust gas cleaner shown is suitable particularly advantageous for carrying out the inven-

Exhaust gas cleaner;

F i g. Fig. 2 is a top plan view of a grille in the lower bed of the exhaust gas purifier;

Figure 3 is a vertical section taken along line 3-3 of Figure 2;

Figure 4 is a vertical section taken along line 4-4 of Figure 3;

F i g. Figure 5 is a vertical section taken along line 5-5 in Figure 1;

Figure 6 is a vertical section taken along line 6-6 of Figure. 1 and

Fig. 7 is a vertical section along the Line 7-7 in Fig. 1.

Form support for the lower grid 24 so that it can expand and contract. Of the Access to the upper part of the storage container 44 according to the method. 25 is through a threaded plug 60 and access

F i g. Fig. 1 is a partial cross-sectional side view of the lower part being secured by a threaded plug

62 formed. The drainage section 66 of the housing 2 has flanges 68 and 70 which define a slot for the sliding support of the upper grid 24 of FIG. A wall 72 separates the discharge section 66 into an upper and a lower part. The wall 72 has flanges 74 and 76 for sliding support of the central grid 24. The end portion 66 also has flanges 78 and 80 which define a slot for the sliding support of the lower grid 24. The upper part of the section 66 is provided with a threaded plug 82 for the removal of the catalyst, while the lower part is similarly provided with the threaded plug 84. Between the above

The exhaust gas cleaner has a housing 2 with a 40 ren and central grid 24, an upper elongated upper part 4 and an elongated layer 86 of oxidation catalyst grains 87. A lower part 6. The upper part 4 is provided with flanges 8, lower layer 88 made of oxidation catalyst grains and 10, which are welded to the flanges 12 and 14 located between the middle and lower of the lower part 6. The upper part 4 grille 24. The exhaust gases exit the exhaust gas cleaner with an elongated rib 16 and the lower 45 through an opening 90 in the bottom of the same.
part 6 is provided with an elongated rib 18; In operation, according to FIG. 1 the exhaust gas purification

these ribs run essentially centrally to the ger a mixture of air and exhaust gases in the over-housing 2 and to the interior of the housing. At each borrowed type fed through a line 92, the side of the upper part 4 is a z. B. to which the Venturi 94 is connected. This is welded to the peri-housing bracket 20. With each bracket 50 external air inlets 96 and a non-removable 20, a second bracket 22 is connected so that the ren, but sliding on the outside of the venturi 94 bracket 20 and 22 a slot for a sliding fit attached ring 98 is provided. This can be moved in such a way as to form a grille 24 in order to carry this grille 24 in such a way that it partially covers the openings 96 in order to reach the conditions. The grille 24 can expand and regulate the amount of air supplied. The exhaust gases draw in as it is heated and cooled. At 55 the venturi 94 from the muffler of an internal combustion engine which is not welded to the bracket 22 is fed to pins 26 and 28. The four slots on each side of the upper part for gases come through the venturi 94 which forms a sliding fit of a grille 24 to provide enough air to support the required grille 24. At high temperature, this can also expand or contract for the subsequent catalytic changes to oxidize the combustible components of the exhaust gases. to deliver from the engine. The mixture of air

On each side of the lower part 6 of the housing are and exhaust gases flows through the line 92 into the bracket 30 and 32 welded on, for example. This housing 2 over the upper grille 24. The gases are in turn form slots for a sliding fit of a distributed over the surface of the grating 24 and gelan grating 24 and thus a support for this grid 24. 65 gene through the upper layer of the oxidation catalyst this grid can expand and contract and then pull through the lower layer of the oxymene, when it is heated and cooled. The dation catalyst. Eventually they pour under that Rib 16 supports the outermost grid 24 against the upper grid 24 and out through the opening 90.

5 6

The oxidizable components in the exhaust gases are required on average 15.8 liters of gasoline per 100 km,

that of the catalyst grains 87 catalytically oxy- which contains 0.53 g of lead per 11. A catalog is

dated. The heat released from this oxidation is used by lyric exhaust gas purifiers, the 7 kg of catalyst

and the heat in the exhaust gases keep the ^{catalyst (approximately 6600 cm 3} catalyst volume) layer of the catalyst grains 87 at an elevated temperature. A car that z. B. 20 percent by weight ca

temperature, preferably in the range of about 490 catalyst used in the first layer and the

up to 730 ° C, once the effective operation has been driven 58,000 km, z. B. in the first

has set. Under these conditions, the layers contain the catalytic converter every 10,000 km.

see gases passing through the catalyst layer, requiring 8 kg of catalyst, and only a sufficiently small proportion of their origin- io the catalyst in the second layer can all

borrowed concentration of oxidizable impurities- 29,000 m are exchanged, whereby 11 kg cat-

worked. The main amount of these impurities is lysator or a total of 19 kg of catalyst

catalytic to carbon dioxide and water vapor oxy- sator are required. If the same car die

dated. the same distance was driven and an exhaust gas

According to one embodiment, the exhaust gas cleaner was used, which was 50 percent by weight

Cleaner of a car for about 10 000 journeys - the catalytic converter used in the first shift and

kilometers used. Then the upper catalyst is the catalyst exchange at the same time intervals.

The first layer requires the removal of the catalyst layer and fresh catalyst that has been carried out

used. This process is carried out in time segments totaling 20 kg of catalyst and the second shift

repeated from 10,000 km. The volume of the top 20 in total 7 kg of catalyst or a total amount

Layer is 20% of the total volume of the two of 27 kg of catalyst. In both cases one occurs

Layers. After driving 38,000 km, there was a sufficient saving of a catalytic converter compared to a

The amount of catalyst from the first layer is a cleaner that has a single catalyst layer

removed and reused in the second shift. used, which contains 7 kg of catalyst, depending on the

With this one can still 22,000 to 29,000 km 25 10,000 km must be replaced and therefore in total

go on. The exhaust gas cleaner results in 41 kg of catalyst required for a 58,000 km journey,

inventive mode of operation a very effective Preferably, the catalyst is from the first

Operation and a surprising reduction in the shift freed from lead dust before moving on to the second

Catalyst costs. Used in an exhaust gas cleaner with one layer.

With a single catalyst layer, the catalyst 30 would expediently be essentially round

be completely replaced after 19,000 km. Oxidation catalyst granules with a diameter

The catalyst is preferably used in the first of the one behind the other in the range from about 0.75 to about 1.35 mm of the catalyst layers lying behind one another. The width of the slot in the grid after approximately 3000 to 19,000 km, preferably un- is therefore slightly smaller than the diameter of the Katagefähr 3000 to 13,000 km, and in the 35 lysator grains, preferably in the range of 0.5 to the following Layer reused. The catalyst - 0.75 mm. The total thickness of both layers of amount in the first layer is about 8 to un-grains is preferably 2.5 to 5 cm.
about 66 percent by weight, e.g. B. 14 to 30 weight As can be seen from Fig. 1, the path of the gas percentage, the total amount. The remainder is upstream of the upper grid 24, a decreasing second layer. The catalyst reused in the second catalyst cross-sectional area perpendicular to the direction of flow is reused and is replaced by the upper grid 24, the inlet grid, for about 18,000 to about 29,000 km of travel. The directional, so that a substantial speed number of kilometers between renewals in the two-component layer perpendicular to the plane of the inlet grille is at least 1.5 times the number occurs. This reduces the pressure over the Katalyder kilometers between renewal in the first 45 satorschicht in the areas that are the entry point layer. closest to the gases increases, and it yields

The best conditions in terms of rapid, essentially uniform pressure drop starting and effectiveness of the removal of the damaging layers through the catalyst layers,
The cross-sectional area of the catalytic converter layers is achieved at reasonable cost if the first catalytic converter layer varies, of course, very strongly depending on the engine, from about 25 to about 55 percent by weight in which the exhaust gas cleaner is used. The cross-sectional area is right, at an angle to the flow lines through the catalytic converter, in the exhaust gas cleaner.

If an efficiency of 85 to 90% is sufficient, gate layer in the range of 0.97 to 20.6 m ² per

the catalyst needs in the first shift after 55 0.45 kg per minute consumed by the engine

Approximately 10,000 km of driving to be renewed. In fuel under the operating conditions that the

in this case the first catalyst bed can correspond to the lowest total energy of the gases which

Of the order of 25 percent by weight of the total enter the catalyst layer; Total energy

catalyst in the exhaust gas cleaner. The initial here means the sensible heat of the gases plus

Charge of catalyst in the second layer will be 60 of the heat generated by the oxidation of the combustible

Replaced by the catalytic converter after a drive of 29,000 km, substances in the gases can be generated. The transverse

which was already used in the first shift. The sectional area of a layer is generally

After a drive of 29,000 km, this replacement will itself be 0.4 to 1 cm ² / cm ³ cubic capacity, in particular 0.52 to

which replaces. Due to the fact that it was 0.8 cm ² / cm ³ . The volume of the layer is im

10,000 km was used in the first shift, 65 is generally 1.8 to 4.6 cm ³ / cm ³ displacement. The geo-

he used it for a total of 39,000 km. Below the metric surface, which is caused by the

"Ride" are the average driving conditions that are formed, is generally about 46 to

understood, ie the drive of a motor vehicle, the 86 cm ² / cm ³ displacement, in particular between 56 and

72 cm ² / cm ³ cubic capacity and thereby preferably more than 66 cm ^ä / cm ³ cubic capacity.

If you have a maximum addition of air to the exhaust gases in the volume ratios of 1 part supplied Air per 4 parts of exhaust gas, the operating ranges of the catalyst bed are generally between 490 and 730 ° C. These temperatures correspond to the effective separation of Hydrocarbons and other additive products resulting from the partial oxidation of the fuel result. 730 ° C is a reasonable operating temperature for the metals used that will support the Catalyst included. The effectiveness of the catalyst starts at around 260 ° C, this corresponds to the oxidation of hydrogen. The oxidation of carbon monoxide and carbonaceous compounds starts little about, d. H. at 290-315 ° C. The rate of separation at this initial temperature however, it is quite low under normal operating conditions. The separation in the order of magnitude of 90% and more is reached in the temperature range from 490 to .700 ° C. The ones from oxidation Heat generated by hydrogen and carbon monoxide raises the temperature to the range that for full activity for the oxidation of hydrocarbons and other decomposition products necessary is.

Claims (2)

Patent claims: 1. A method for the catalytic oxidation of internal combustion engine exhaust gases by successive Passing the exhaust gases through two arranged one behind the other in the direction of flow Catalyst layers, characterized in that the first exposed to the exhaust gases Catalyst layer made from fresh catalyst grains with an average grain size between about 0.075 and 0.135 cm is then reused in the second catalyst layer. 2. The method according to claim 1, characterized in that the reuse of up to about 3,000 to 19,000 kilometers of driving used catalyst grains of about 8 to 66% of the total amount by weight of catalyst making up the first catalyst layer in the second catalyst layer about 18,000 to 29,000 kilometers traveled by an internal combustion engine vehicle he follows. Considered publications:
German patent specifications No. 231072, 564265,
630414, 644734;
British Patent No. 435 650. 1 sheet of drawings 803 567/461 6.68 © Bundesdruckerei Berlin