DK155541B - METHOD FOR REDUCING PARTICULATE POLLUTION IN EXHAUST GAS FROM DIESEL ENGINES AND DIESEL ENGINE FOR EXERCISING THE PROCEDURE - Google Patents

Description

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DK 155541 B

The invention relates to the reduction of harmful particulate pollutants found in exhaust gases from diesel engines.

Gases from diesel engines often contain finely divided particles of hydrocarbons and / or carbon or other solid materials which form in the form of smoke. The smoke from a diesel engine consists of solid / liquid particles (namely, solid particles with a liquid outer cover), solid chain aggregates in which 10 spherical particles with a diameter of between 100 and 800 Å are bonded together, liquid sulfates, liquid hydrocarbons and gaseous hydrocarbons. The solid / liquid particles with adsorbed liquid hydrocarbons and the solid chain aggregates usually consist of high molecular weight organic compounds and / or inorganic sulfates.

White smoke is generated when the engine first starts, which is a result of the condensation of water vapor on particles present in the exhaust gas so that a fine mist is formed. Black smoke is generated by diesel engines when the engine is heated and contains a relatively high proportion of carbon particles. In blue smoke there is some carbon, but also a relatively high proportion of gaseous organic compounds such as aldehydes. Ca. 90% of these 25 smoke-forming particles have a maximum dimension of less than 1 µ, which is within the inhalable particle size, and the maximum dimension of the remaining 10% of these smoke-forming particles is less than 4 yes. 1 2 3 4 5 6 When the diesel engine is first heated and is under full 2 load, the operating temperature can be so high that of 3 burning of the particulate pollutants 4 takes place even without catalyst, namely at approx. 600 ° C or above. The problems with the particulate contaminants 6, on the other hand, arise at start and at low loads, where there is a need to lower the combustion temperature, so that the particulate contaminants can settle.

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2 is burned thereby avoiding clogging of the catalyst mass.

It is thus the object of the invention to provide a process of the kind set forth in the preamble of claim 1, by which it is possible to burn simple particulate pollutants in the exhaust gas under all operating conditions of a diesel engine, including at start-up and low loads 10 thereof.

The method according to the invention, which is of the kind set forth in the preamble of claim 1, is characterized by the method of claim 1. The smoke-forming particles or particulate contaminants will enter the catalyst chamber in the process in which they are contacted with the catalyst so that the entire amount of the particulate contaminants or a substantial portion thereof will also be burnt during starting or low loads of diesel engines. because it has been found that the catalyst reduces the firing temperature from the non-catalytic value of approx. 600 ° C to a temperature of about 200-210 ° C. This avoids clogging of the catalyst, the useful operating period of the catalyst is considerably longer, and the process according to the invention is therefore considerably more economical than known processes of this kind. At lower temperatures, the particulate pollutants are oxidized and thus disposed of from the catalyst, the faster it is regenerated and the lower the back pressure, which improves the operating economy.

It is known from GB patent specification 1,471,138 catalytic systems for the treatment of exhaust gases in cars. First, the present invention focuses solely on diesel engines, and then it focuses on the present invention.

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The present invention relates to particulate contaminants in the exhaust gas, ie soot, whereas the known catalytic systems are directed solely to the treatment of exhaust gases from explosive engines. This is also consistent with the treatment means used in the invention are described as filters, which is not the case with the known treatment means. Thus, the specific problem that the present invention solves is not disclosed in GB Patent No. 1,471,138, nor is the solution thereof disclosed in GB Patent No. 1,471,138.

10

A preferred embodiment of the method according to the invention is characterized by the characterizing part of claim 2. This results in a particularly low combustion temperature of soot.

15

The diesel engine according to the invention, which is of the kind specified in the preamble of claim 3, is characterized by the characterizing part of claim 3. Due to the particular structure and composition of the catalyst, it is achieved that the entire amount of the particulate contaminants or a substantial part thereof will also be burnt during starting or low loads of the diesel engine, because the catalyst, as mentioned, reduces the combustion temperature from the non-catalyzed value of approx.

600 ° C to a temperature of about 200-210 ° C. This avoids clogging of the catalyst, which means a low back pressure and a good operating economy.

Particularly preferred embodiments of the diesel engine according to the invention are characterized by the characterizing part of claims 3-10.

It is known from United States Patent No. 3,911,676 that exhaust gases from an engine can be fed directly into a chamber with a catalyst layer, and 35 means of increasing turbulence are known from there. It is furthermore apparent from column 2 of the patent, lines 1-11, 4

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that the exhaust gases temperature is above 800 ° F, preferably between 1000 and 1200 ° F (above 427 ° C7 preferably between 538 and 649 ° C). However, the particular soot problem that occurs in diesel engines during take-off and at low 5 loads is not part of this known technique.

It is also known from US Patent No. 4,087,966 that exhaust gas from engine cylinders can be directly fed to a catalyst. Furthermore, it is clear from column 11 of the patent, lines 27-32, that a normal temperature of the exhaust gas is approx. 600 ° C. Here, the burning of the soot particles is used by means of high temperatures. It is an alternative to this prior art that the invention provides, the invention offering a burning of soot at low temperatures so that burning can also take place at start and low loads.

Finally, it is also known from British Patent Specification No. 1 446 856 that one can build a catalyst layer of a carrier which may be of a metallic material, a primary layer of an oxide and a secondary layer of other platinum, palladium or rhodium.

From page 6 of the patent, lines 18-29, it appears that the preferred temperatures for the exhaust gases at the catalytic oxidation are between approx. 500 and 850 ° C.

This prior art does not concern the burning of soot, and much less the use of low temperatures to regenerate the filtration systems that have been clogged with soot.

In connection with the prior art, corresponding to the three prior patents, which can be said to illustrate the technique set out in the preamble to the main claim, the catalyst system is utilized at relatively high temperature. By the method according to the invention, which otherwise relates exclusively to 35 diesel engines as opposed to the above three patents, all of which relate to internal combustion engines in general.

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5, the catalyst is active at a significantly lower temperature, namely corresponding to a burning of particulate contaminants between ca. 207 and ca. 265 ° C, which represents a significant technical advantage, the desired soot burning also taking place during take-off and at low loads.

Usually, the catalytic oxidation of carbon particles takes place at ca. 400 ° C, whereas the normal temperatures for the combustion of such particles are 700-800 ° C. For hydrocarbon particles, catalytic oxidation will occur at temperatures of approx.

200 ° C. The effect of a catalyst in relation to the temperature at which catalytic oxidation of 15 particles entrained in the exhaust gas stream by a diesel engine took place was studied. A number of sample catalysts were prepared. The catalysts included a substrate made from 310 stainless steel wires of 0.025 cm diameter 20 rolled down to a strip whose thickness is 0.01 cm, a layer of alumina and a layer of one or more metals of the platinum group in an amount of 2.46 mg / g alumina. A portion of coated wire was cut from a catalyst and gradually heated, raising the temperature together with particulate matter, collected from the exhaust gas stream in a diesel engine, into the sample bowl of a differential scanning colorimeter (a DSC) in an atmosphere of 1% oxygen in argon. Samples of the atmosphere above the sample bowl were fed to a mass spectrometer via a heated capillary tube. Four mass numbers were detected: carbon monoxide (44), double-charged argon (20), oxygen (32) and water (18) or nitrogen and carbon monoxide (28). The temperature at which the differential imaging of DSC had its peak was assumed to be the temperature at which the combustion of the particulate materials occurred. This temperature can be referred to as the "burning temperatureM.

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«'- 6

The results are given in the following table:

Aluminum content Catalytic Burning 5 (g / g wire) metals temperature (° C) 0.33 5.7% Rti 94.3% Pt 235 0.28 67% Pt 33% Pd 207 0.30 Pd 265 0.28 Pt 220 10

The combustion temperature of particulate material from the exhaust gas stream of a diesel engine, 207 to 265 ° C, is significantly lower than the temperature at which combustion takes place when no catalyst 15 is present.

Since the presence of a catalyst allows oxidation of the smoke-forming particles in a gas to occur at a lower temperature than the normal temperature at which combustion takes place when it is desired to carry out the catalytic oxidation of any smoke-forming particles in the exhaust gas from a gas. as a result, only little or no heating is required. This is because the temperature of a diesel engine's exhaust gas is approx. 400 ° C when operated under medium or full revs, so that no exhaust of the exhaust gases emitted from the engine is required before passing the exhaust gas over a catalyst.

30

The filamentous metallic substrate may be in the form of a wire and is arranged to provide maximum contact between the catalytic metal and the exhaust gases. Preferably, the filament is in a flat form which usually appears by rolling down prior to the precipitation of leaching coatings and catalytic metal. During the operation of one

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7 diesel engine or a similar engine in which there is an excess of air or oxygen in the combustion chamber ensures such contact that a substantial proportion of the pollutants, as described above, undergo catalytic oxidation.

A preferred embodiment of the diesel engine according to the invention comprises that the housing comprises a plurality of inputs corresponding to the number of exhaust openings in the engine and that the apparatus is disposed in the immediate vicinity of the engine exhaust openings.

The catalyst used in the diesel engine comprises: (a) a split substrate disposed in the path of the gas stream to create turbulence in the exhaust gas stream; b) an adhesive refractory layer of metal oxide disposed on the surface of the substrate; and c) a catalytic metal which may be Ru, Rh, Pd, Ir,

Pt, Fe, Co, Ni, V, Cr, Mo, W, Y, Ce, their alloys and intermetallic compounds containing at least 25% by weight of one or more of the indicated metals disposed on the surface or through the entire metal oxide, refractory layer.

The refractory metal oxide layer preferably contains in the form of oxides one or more members of the group consisting of Mg, Ca, Sr, Ba, Sc, Y, lanthanides, Ti, Zr, Hf, Th , Ta, V, Cr, Mn, Co, Ni, B, Al, Si or Sn. 1

A preferred refractory material is alumina hydrates, but stabilizing oxides such as BaO and oxides.

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promoting catalytic activity such as TiO2, ZrO2,

HfC> 2, ThC> 2, Cr2 ° 3 ° 9 N: * - 0 'may be present.

A preferred form of the catalyst substrate comprises a fabric made of woven or knitted yarn and an even more preferred form is woven or knitted yarn that has been rolled down prior to woven or knitted form. Suitable alloys which can be used in the fabrication of the wire are corrosion resistant, and especially oxidation resistant base metal alloys.

Examples of such base metal alloys are nickel and chromium alloys with a total content of Ni plus Cr greater than 20% by weight, and alloys of iron which also contain at least one of the elements chrpm (3-40% by weight) , aluminum (1-10 wt.%), cobalt (trace-5 wt.%), nickel (trace-72 wt.%) and carbon (trace-0.5 wt.%). Such substrates are described in German Publication No. 2 450 664.

Other examples of base metal alloys capable of withstanding the extreme conditions required are iron-aluminum-chromium alloys which may also contain yttrium. This last alloy may contain 0.5-12% by weight

Al, 0.1-3.0 wt% Y, 0-20 wt% Cr and the rest Fe. These 25 are described in U.S. Patent No. 3,298,826. Another assortment of Fe-Cr-Al-Y alloys contains 0.5-4% by weight

Al, 0.5-3.0 wt.% Y, 20.0-95 wt.% Cr and the rest Fe, and these are described in U.S. Patent No. 3,027,252.

Alternatively, the base metal alloys may have less corrosion resistance, e.g. soft steel, but with a protective coating covering the surface of the substrate as described in our co-pending English Application No. 7,903,817, dated February 2, 1979.

When using wire as a substrate, the thickness lies therein

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9, preferably between 0.0025 and 0.051 cm, especially between 0.0025 and 0.030 cm.

5 In the drawing: FIG. 1, 2 and 2A are various embodiments of the apparatus for reducing pollutants in the diesel engine according to the invention; 3 and 4 different alternatives to the device in the apparatus which allows gas passage to the exhaust pipe, and rich. 5-14 graphic depictions of the result of the later 15 specified driving tests, where the dotted lines correspond to the later specified baseline numbers and the fully drawn lines; lasts to the numbers with the later specified modified engine.

In one embodiment of the invention, the catalyst is present in a reaction tube located substantially centrally in the exhaust chamber. The embodiment will be described with reference to FIG. 1. The outer wall, 1, of the exhaust chamber has openings 7, 8, 9 and 10 which extend up to and are continuous with respect to the exhaust openings of the cylinders / Cg an outlet 12, in the immediate vicinity of the exhaust pipe 11. The reaction tube 2, supported in the chamber by struts 5 and 6, contains the supported catalyst 3. The reaction tube is arranged so that the exhaust gas at the stage of entering 30 into the exhaust chamber must pass through the reaction tube and thus come in close and continuous contact the catalyst before leaving the exhaust chamber and entering the exhaust pipe. The exhaust gas flow through the exhaust chamber is generally denoted by the labeled 35 arrows F ^, F2, F ^, F ^, F ^ and Fg. Combusted gas flows in from the cylinder openings through the openings 7, 8, 9 and 10 and flows along the reaction tube 2 and into the exhaust pipe 11. A retaining rod 4 is arranged transversely

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10 of the outlet of the reaction tube to ensure that the catalyst remains in position.

The catalyst support is preferably knitted wire mesh. This can be formed into a single monolith, or: it can be made so that there are several annular sections.

The refractory layer and the catalytic layer may be applied separately to each section or after the sections have been joined. As an alternative, the refractory material and the catalytic layer may be applied to the support, in sections or interconnected, after it has been introduced into the reaction tube.

A further embodiment will be described with reference to FIG. 2. The outer wall, 21, of the catalytic chamber has openings 27, 28, 29 and 30, in the immediate vicinity of and in continuity with the exhaust openings of the cylinders, and an outlet 32, in the immediate vicinity of the exhaust pipe 31 · Catalyst 23 / comprising a support, a leach coating layer and a catalytic metal, arranged in such a way that, at the stage of entry into the catalyst chamber, the exhaust gas 25 is forced to pass through the spaces of the specified catalyst before leaving chamber and enters the exhaust pipe. The exhaust gas flows through the catalyst chamber, as indicated by the labeled arrows, 30 F42 »F43» f44 ° S f45 * The gas flows in from the exhaust openings as shown by F ^, F ^, F ^ and F ^ and then through the catalyst and into the exit pipe. 22 as shown by F45 * 35 In this embodiment, the catalyst support is preferably knitted thread, which may be in sections or as a unit, but if it is in sections, e.g. of monk configuration, these are usually interconnected before the carrier is placed in the chamber.

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11

One end of the carrier is closed by attachment, e.g. by welding, of a disc 26 thereto, and an annular disc 25 at the other end holds the carrier in position. The supported catalyst is arranged in the catalyst chamber as shown in FIG. 2 by attaching the ends covered with the washers 25 and 26 to the outer wall of the chamber. In order to ensure that the carrier does not collapse inwardly, a cylindrical and perforated exit tube 22, 10 arranged in the catalyst chamber allows gas to pass therethrough and proceed to the exhaust tube 31. The tube 22 may be constructed of wire mesh or it may be a perforated metal pipes with holes or gaps.

FIG. 3 shows an alternative embodiment in which, instead of a perforated exit tube in the catalyst chamber, a series of five rigid rods 100-500 running along the length of the chamber is used. These are maintained in a mutually fixed spatial relationship, thereby holding the supported catalyst rigidly in place within the chamber, using spacer plates 600. The spacer plates in pairs connect three of the five rods, and are usually at right angles to each other. relative to each other, being arranged along a diameter of the central cylindrical exit tube. Two or more pairs of spacer plates may be used and are usually arranged at regular intervals in the longitudinal direction of the chamber. Alternatively, spacers may be used instead of rods, where they would be continuous over the length of the chamber, as shown in Fig. 4. Rods and spacers need only be constructed of a material resistant to oxidation up to at least 800 ° C.

A further embodiment will be described with reference to FIG. 2A, for convenience, only two outlet openings are shown. The outer wall 100 of the catalyst chamber has openings 101 and 102 in the immediate vicinity of And in continuity with the exhaust openings of the cylinders,

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12 and an outlet 103 in the immediate vicinity of the exhaust pipe. Catalyst 104, comprising a carrier, refractory material and catalytic metal, is arranged such that the exhaust gas must pass through the catalyst before leaving the chamber. The catalyst is provided in the chamber using spacer plates 105, as described above. One end of the spacer plates 109 is fixed to the chamber wall 100 and a washer or metal plate, 108, is attached to the other end of the spacer plates to ensure that no exhaust gas can leave the chamber without passing through the catalyst. The exhaust gas flows into the chamber through the openings 101 and 102, and down through the bushings 106 and 107, into the interior space 110 provided by the spacer plates 105. The exhaust gas then flows through the catalyst in the outward direction and then through the outlet 103. The exhaust gas flow is indicated by the labeled

Arrows F9q “F109 '20

The support for the catalyst is preferably knitted thread, which may be in four sections or in three units. If the support is in sections, for example, of monk configuration, they are usually interconnected before the support is introduced into the chamber.

EXAMPLE 1

Z

The multi-cylinder engine with a volume capacity of 2000 cmr in a vehicle available on the market powered by diesel power was modified to demonstrate the results obtained during operation according to the invention.

The engine was provided with a catalyst chamber as described in the first embodiment (Fig. 1) of the invention, as described above. A knitted catalyst support of the net type was prepared from wire having the following composition:

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13 Weight- ^ 3 Cr 15 Eel 4 Y 0.3

Fe residue On this support, a refractory material was precipitated, consisting of gamma-alumina stabilized with 5 wt- $ BaO and a catalytic metal layer consisting of platinum and palladium.

The Pt / Pd content was 2.5 g total (Pt: Pd ratio 1: 1) of 3 a total catalyst volume of 84 cm. The results 1, obtained by running the engine using the diesel cycle LA4, as explained in Table 11. The hydrocarbons, carbon monoxide, nitrogen oxides and particulate materials present in the exhaust gases were measured in g / 1.6 km. Baseline measurements were first performed without any catalyst in the chamber, but with back pressure set to the same value as with the corresponding catalyst. The results are given in Table 1: 25 TABLE 1

Particle Form HC, g / 1.6 km GO, g / 1.6 km N0 „f g / 1.6 km with material _ _ _ g / 1.6 km

Baseline 1.54 1.93 1.53 0.85 number

Modified 0.214 1.892 0.979 0.44 engine

It turned out that the back pressure was high.

35

EXAMPLE 1A

Further experiments were carried out using the same catalyst as in Example 1 above. Emissions corresponding to particulate matter in the base

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The 14 line using the same vehicle was determined in four tests as numbers denoted g / 1.6 km. These experiments were extended to include thermogravimetric determinations of the percentage of carbon and volatile materials present within the particulate material and of the value of the size measured in the unit of sulfate / 1.6 km available within the particulate material. The results obtained are shown in the following table:

Basislinietal

Experiment Particle% Volatile No. Met Material,% Carbon Substances Sulfates, 15__g / 1.6 km____ g / 1.6 km 1 0.582 62.5 37.5 0.015 2 0.512 58.0 42.0 0.011 3 0.509 59.6 40.4 0.012 4 0.482 61.8 38.2 0.012 20 Note: All the above measurements were completed on a hot run cycle of type LA4, as explained in Table 11.

25

The full baseline emissions determined for HC, CO and NO

X

was also determined, the results being as follows:

Test No. HC, g / 1.6 km CO, g / 1.6 km NO ^ .g / l ^ km 30 1 0.350 1.564 1.775 2 0.339 1.529 1.803 3 0.354 1.561 1.786

A catalyst chamber was constructed within the constraints existing in the vehicle, without making any modifications to the design of the engine assembly.

This results in a catalyst volume of 0.9 liters, which was thought to be inappropriate, but for which complete tests were completed. The results of these are as follows:

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15

Experiment with Material, Sulfates, No. 1/6; 6 km ° / o Carbon g / 1.6 km 1 0.494 79.4 20.6 0.036 2 0.441 76.4 23.6 0.037 5 3 0.444 75.3 24.7 0.035 4 0.515 67.3 32.7 0.055 5 0.466 63.4 36.6 0.064 6 0.492 76.1 23.9 0.051 Note: The vehicle had driven 805 road miles before the first test and the entire test period was completed, but urban driving conditions were simulated using the LA4 cycle, as explained in Table 11.

The results obtained for HC, CO and NOx emissions were as follows:

Test No. HC, g / 1.6 km CO.g / 1.6 km NO g / 1.6 km 1 0.224 0.979 1.892 20 2 0.238 1.073 1.874 3 0.215 0.981 2.014 EXAMPLE 2 Another catalyst chamber as described in the a second embodiment (Fig. 2) was mounted on the engine. A knitted carrier made of the same thread as that used in Example 1 was used again with a refractory gamma-alumina material. The layer of catalytic metal 30 comprises 7.5 wt.% Rhodium and 92.3 wt.% Platinum. The two volume catalyst volume was 1803 cm \ The weight of the carrier used was approx. 1.6 kg, 5 g of refractory material, namely alumina, and 2.9 g of the catalytic metals Rh and Pt in the above ratio were applied to the carrier. Baseline measurements were made without any catalyst present in the chamber attached to the

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16 engine. The results are given in Table 2, with the car driven through the LA4 cycle with a hot start.

TABLE 2

Particle form with materials, HC, g / l, 6 km CO, g / 1.6 km N0 ::, g / 1.6 km g / 1.6 km

Baseline number 0.35 1.55 1.8 0.57

Modified engine 0.2 0.5 2.1 0.31 10

The back pressure without any catalyst present in the chamber was 6.10 cm Hg and 8.89 cm Hg when the catalyst was present in the chamber. The atomic ratio C / H of the particulate materials present in the exhaust gas 15 before and after passage through the catalyst chamber was measured and it is given below in Table 3 with a hot start for the engine.

20 TABLE 3 C / H ratios in particulate matter in exhaust gas Before catalyst After catalyst 25 C 63 80 H 37 20

This is a measure of the reduction of the content of organic compounds in the exhaust gases. The concentration of 30 sulphate present in the exhaust gases before and after the catalyst was measured and it was found to be unchanged.

Further results obtained are given below in Table 4 with a cold start for the engine.

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17 TABLE 4

Particle HC, g / l, 6 km CO, g / 1.6 km N0X, g / 1.6 km te ^ ale? ® '__ _ _ g / 1.6 km 5 Baseline number 0.41 1.3 1 , 9 0.62

Modified engine 0.242 0.274 1.86 0.42

Modified engine 0.218 0.252 1.86 0.4 10 The composition of the present particulate matter in the exhaust gas is given below in Table 5 with a cold start for the engine.

Table 5 15

Sulfates, Carbon, Adsorbed HCs, g / 1.6 km g / 1.6 km _g / 1.6 km

Baseline number 0.11 0.34 0.165

modified

Engine 0.11 0.28 0.025 20

The results in Tables 2, 3, 4 and 5 were obtained using a commercially available automobile propelled by a diesel engine. The engine had been modified with a catalyst chamber installed in place as previously described.

The car had completed an 805 km round trip in a test circuit before driving through the taxi cycle at a maximum speed of 40 km / h, as explained in Table 11.

30

Further experiments were conducted using a car with a commercially available diesel engine. A catalyst chamber, as described in the second embodiment, as shown in FIG. 2, was mounted on the 35 engine. A support of type 310 stainless steel wire with cross section was made

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18 0.010 cm before knitting. Type 310 stainless steel is austenitic stainless steel with a carbon content of up to 0.25 and containing manganese, phosphorus, sulfur and silicon. The support was coated with a gamma-alumina wash-out coating. The lag.

of the catalytic metal comprises 5.7% rhodium and 94.3% platinum with a load of 883 g / m. The weight of thread used was 3,200 g with 1,200 g refractory material. The total volume of catalyst used was 3556 cm.

The weight of particulate matter present in the exhaust gas was measured by passing a known volume of exhaust through a dilution tunnel where it was diluted with a set volume of air to prevent the solids from settling before passing the gases through a filter pad . The weight of particulate material allows one to calculate a value for the particulate material in g / hr. The particulate material present in the exhaust gas was further analyzed to determine the thermogravimetric weight and weight of volatile components, hydrocarbons, carbon and sulfate. Using the above method, a number of filter pads were obtained for analysis.

The weight of sulfate in the particulate material was measured by wet chemical analysis of the particulate material. Another sample was introduced at a thermogravimetric weight where the sample was heated in an inert atmosphere to a temperature of 780 ° C until the weight 30 became constant. The weight loss between the initial weight and the new weight is equal to the weight of the volatile components present. Air was introduced and the heating continued until the weight became constant again. The difference between this weight and the value of the previously constant weight indicates the weight of carbon components present. The remaining part was ash and not burnt.

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19 bare material such as iron.

Baseline measurements were taken with a manifold connected to the engine instead of the chamber containing the catalyst. Measurements were taken with the car while it was being driven through the cold start LA4 diesel cycle and these are given in the following table 6. The results of the LA4 hot cycle diesel cycle are given in table 7 and the results in the 10 driving test on highway is given in the following table 8. The highway test used was the standard test cycle used in the United States for fuel consumption tests.

15 The results given in Tables 6 and 7 are shown in graphical form in FIG. 5-9, LA4 cold start cycle, and in FIG. 10-14 for LA4 cycle hot start (baseline dashed line and modified motor fully drawn lines). The content of the LA4 cycle is explained immediately after Table 11.

The reduction of the concentration of particulate matter (measured in g / 1.6 km) in a diesel engine according to the invention is shown in Table 6, column 3. The rectification of adsorbed hydrocarbons and carbon present in the particulate material is shown in column 7 and 9, respectively. Sulfattal shows an increase in certain cases, but the absolute level of emission remains low.

30

Counter pressure measurements were made. This is the difference between the pressure of the gases when leaving the exhaust openings and when leaving the chamber. The results are given in Table 9 when the car is driven through the LA4 cycle and in Table 10 for the driving test on the main road.

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23 DK 155541B

TABLE 9

Back pressure in cm Hg Run km Baseline After catalyst chamber

Max, Avg. Max. Aver.

Yarm start 0 7.92 1.60 7.32 1.91 2897 8.69 2.54 6759 9.65 2.49 7886 9.32 2.31 8851 15.56 4.83 - 9817 6.15 1, 65 11.63 3.63 13679 8.41 2.44 .20117 6.05 2.16

Cold start 0 6.71 1.22 8.99 2.18 2897 8.00 2.92 6759 11.68 2.44 7886 11.43 2.41 8851 12.34 4.19 9817 12.291 1.55 11, 73 3.51 13679 8.33 2.44 20117 6.35 2.11 High figure is probably due to buildup of soot deposits

24 DK 155541 B

TABLE 10 Back pressure in cm Hg Driving km Baseline After catalyst chamber

Max. Aver. Max. Aver.

2897 8.48 5.03 9817 5.08 2.79 10.29 7.37 13679 7.92 5.08 TABLE 11 Back pressure in cm Hg Miles km Baseline After catalyst chamber

Max. Aver. Max. Aver.

0 7.32 1.42 8.13 2.03 13679 11.38 1.55 11.73 3.51 In the foregoing description, the following abbreviations have been used and the meaning thereof is given below.

CVS - sampling at constant volume 5 LA4 - Los Angeles cycle as determined by the Enviromental Protection Agency (EPA) and the United States is a standardized trial cycle designed to simulate driving to work under such traffic conditions prevailing in Los Angelo lesson. This is another test to which all new vehicles are exposed.

Taxi cycle - a trial cycle that is approx. 80 km long, approved by EPA and carried out at low speeds up to 40 km / h and extensive periods when the 15 car is stationary and the machine goes idle.

Claims (10)

A process for reducing particulate pollution from diesel engine exhaust gas, in which the exhaust gas from the cylinders of the engine is fed into a chamber containing a catalyst on a support of such construction to produce turbulence and particulate contaminants present in the exhaust gas come into contact with the catalyst and at least a portion of the particulate contaminants are subjected to catalytic oxidation, characterized in that the catalyst having the character of a filter is a substrate made from a filamentous material. , knitted, woven or crushed metallic material, a primary layer of refractory material, preferably a metal oxide applied to the substrate, and a secondary layer of a catalytic material applied to the primary layer, and the catalytic material is selected from Ru, Rh, 20 Pd, Ir, Pt, Fe, Co, Ni, V, Cr, Mo, W, Y, Cé ', alloys containing at least one of the metals specified, and intermetallic compounds containing at least 20% by weight of one or more of these metals. Process according to claim 1, characterized in that the catalytic material comprises 5.7 - 7.5% by weight Rh and 94.3 - 92.5% by weight Pt. The diesel engine for use in the method of claim 30 1 or 2 and comprising an apparatus for reducing pollutants present in the exhaust gas emitted from the engine having at least one exhaust port, characterized in that the apparatus comprises a housing defining a chamber containing a catalyst, the catalyst comprising a substrate made from a film-like metallic material in knitted, woven or crushed form, a primary layer of refractory material , preferably a metal oxide applied to the substrate and a secondary layer of a catalytic material applied to the primary layer and the catalytic material selected from Ru, Rh, Pd, Ir, Pt, Fe, Co, Ni, V, Cr, Mo, W, Y, Ce, alloys containing at least one of the indicated metals and intermetallic compounds containing at least 20% by weight of one or more of these metals and the chamber having a input into communication 10 with exhaust the opening through which the exhaust gas emitted from the engine is fed into the chamber and passed through the catalyst prior to passage through an exhaust system into the atmosphere. Engine according to claim 3, characterized in that the housing comprises a number of inputs corresponding to the number of exhaust openings in the engine and that the apparatus is arranged in the immediate vicinity of the engine exhaust openings. Motor according to claim 3, characterized in that the metallic substrate is in the form of a band with at least two substantially flat, opposing surfaces and that the filamentous metallic material is in the form of a wire. 25 Motor according to claims 3 to 5, characterized in that the layer of refractory metal oxides is selected from the Mg, Ca, Sr, Ba, Sc, Y, lanthanides, Ti, Zr, Hf, Th, Ta, V, Cr, Mn, Co, Ni, B, Al, Si and Sn, and that the first layer 30 is made of Al2 O3, alumina hydrates, BaO, TiO2, ZrO2 / HfO2, Tt102 or Cr2 ° 3 * 7. Motor according to claim 3, characterized in that the substrate is made from a corrosion resistant alloy containing a base metal, in particular a nickel and chromium alloy having a total content of 27. nickel and chromium greater than 20% by weight. An engine according to claim 7, characterized in that the substrate is made from an alloy of 5 iron, including at least one of the elements chromium (3-40 wt%), aluminum (1-10 wt%), cobalt (trace) to 5 wt%), nickel (trace to 72 wt%) and carbon (trace to 5 wt%). Engine according to claim 8, characterized in that the base metal alloy comprises yttrium in an amount between 0.1 and 3.0% by weight. Motor according to claim 3, characterized in that the substrate is made from a metallic material with a thickness within the range of 0.0025 to 0.051 cm. , 20 25 1 35