LU82550A1 - REDUCTION OF FUMES AND OTHER HARMFUL CONSTITUENTS CONTAINED IN GASES, AND PARTICULARLY IN EXHAUST GASES - Google Patents

Description

BIr-2909 / EM / BM

0 2 5 "5 0 GRAND DUCHY OF LUXEMBOURG

Patent No ............................................... .....

of ................... Monsieur the Minister of National Economy and the Middle Classes

Title issued: ........................................ d) S · fôf „, , „V,,. „C ^ Æl Industrial Property Service

LUXEMBOURG

Invention Patent Application I. Application, £ 800. Known as JOHNSON, MATIHEÏ & CO LIMITED, 43 Batton Garden, ______________________________________________________ (1)

London EC1S 8EE ...... Great Britain ...................................... .................................................. .................................................. ............................

represented vor E.Meuers & E.Freylinqer, Ing.cons.en propr.ind ** 46 rue (2) du CimetièreΛ LuxembourgΛ act as agents filing ........ this ...... twenty -five June nineteen hundred and eighty ___________............................. (3) * to _____ l.ÎL · ..... ......... hours, at the Ministry of National Economy and the Middle Classes, in Luxembourg: ". 1. the present request for obtaining a patent for an invention concerning: "Reduction of smoke and other harmful constituents contained in _____________________ (4) gases, and in particular in exhaust gases" ...... .................................................. ......................................

declares, assuming responsibility for this declaration, that the inventor (s) is (are): 1. Bernhard Edvard ENGA # Boyn Valley Road, Maidetmead3 BerkshireΛ GB (5) 2. ..... Edward Rigby MIDDLETON3 67 Wyootribe Lane3 Wooburn Green, Eigh Wgoombe * ........... Buokinghamshire, ..... G. B ................................................. .................................................. ....

3. ..... Stephen Leslie CUTMORE, 12 Penroatk Avenue, Reading »Berkshire3 G.B ........................

2. the delegation of power, dated JtäßfteSk ........................................ ...... on ..lß..JMlrR..ÄRß.Q ..........................

3. description in language ...... ............. i ^^ Ç.ÇQ.Ç.Ç ............... ................ of the invention in two copies; 4. ...... drawing boards, in two copies; 5. the receipt of the fees paid to the Luxembourg Registration Office, on June 25, one thousand nine hundred and eighty claims for the above patent application the priority of one (s) request (s) from (6). ....................patent............................. ...................... filed® in (7) ...................... .................................................. .......

the twenty-ninth of June one thousand nine hundred and seventy nine f ...... bous the No 7922620 ................. (8) and ....... .................................

in the name of ...... I &.,. âé] p08gnte .................................. .................................................. .................................................. .................................................. ............. (g) elect domicile for him / her and, if designated, for their proxy, in Luxembourg ................ ........................

46 ...... rue du Ûimetièrer ....... LuxenÈQUrg ................................ .................................................. .................................................. .................... (io) requests the grant of a patent for the invention for the subject described and represented in the abovementioned appendices, - with adjournment of this delivery at .................................... month.

* T, Pfim of agents ....................

.........

I / Π. Deposit Minutes

The above application for a patent for invention has been filed with the Ministry of National Economy and the Middle Classes, Industrial Property Service in Luxembourg, dated: June 25, 1980 „......... ·. , Pr. The Minister. . at _______ 15 __________hours / \ of the National Economy and the Middle Classes, 1; / \ P · at.

Bowl [/ A 68007 ......

i. . ....... ................................. ..

ν '"·"' i j BL-2909 / EM / BM JC 70R / A 3419 WIT 89

PATENT

Λ

On behalf of: JOHNSON, MATTHEY & CO LIMITED

REDUCTION OF SMOKE AND OTHER HARMFUL CONSTITUENTS CONTAINED IN GASES, AND PARTICULARLY IN EXHAUST GASES.

Invention: Bernard Edvard ENGA

Edward Rigby MIDDLETON Stephen Leslie CUTMORE

/ -J— Priorities for patent applications in GREAT BRITAIN n ° 7922620 of June 29, 1979 "and n ° 8010768 of March 31, 1980 T. -

S

j / * '1, REDUCTION OF SMOKE AND OTHER HARMFUL CONSTITUENTS CONTAINED IN GASES, AND PARTICULARLY IN EXHAUST GASES.

The present invention relates to the reduction of fumes and other harmful constituents contained in the gases, and in particular in the exhaust gases.

The gases produced by steam generators and internal combustion engines often contain finely divided particles of hydrocarbons, carbon and / or other solid materials which give rise to the formation of fumes. The fumes produced by a diesel engine are made up of solid / liquid particles (i.e. solid particles coated with an outer liquid layer)? solid aggregates formed of particles, of which

O

10 the diameter is around 100 to 800A, linked together? liquid sulfates? liquid and gaseous hydrocarbons.

Solid / liquid particles are generally formed of carbon particles having adsorbed liquid hydrocarbons, while solid aggregates are generally formed of high molecular weight organic compounds and / or mineral sulfates.

Various types of smoke can be produced: - white smoke, produced when the engine is cold, which results from the condensation of water vapor on the particles contained in the exhaust gases, forming a fine mist; 20 - black fumes, produced by diesel engines when the engine has warmed up, and which contain a relatively high proportion "· of carbon particles; I— blue fumes, which contain a little carbon but also a relatively high proportion of gaseous organic constituents such as for example aldehydes.

About 90% of these smoke-generating particles have maximum dimensions less than 10, which is of the order of magnitude of the particles. likely to be inhaled, while the other 10% have 7 maximum dimensions less than 4y.

/

The present invention relates to a process making it possible at least to reduce the quantity of fumes contained in the gaseous effluents by catalytic oxidation of the smoke-generating particles contained in these gases.

The present invention also relates to a method making it possible to reduce the quantity of harmful particles and gases present in the exhaust gases of an internal combustion engine.

The present invention also relates to an internal combustion engine, of the gasoline or diesel type, modified so that it produces only a considerably reduced quantity of harmful particles and gases.

In the present description and in the claims to which it gives rise, the term "pollutants" means hydrocarbons, carbon monoxide and nitrogen oxides formed by internal combustion engines, as well as smoke-generating particles as defined. above. According to a first embodiment of the invention, the internal combustion engines comprise means for reducing the pollutants contained in the exhaust gases produced by the engines comprising at least one exhaust orifice, these means comprising: - a casing defining an enclosure or chamber containing a catalyst, this catalyst being formed of a substrate made of a filamentary metallic material, woven, knitted or ground, of a first layer of a refractory metal oxide fixed on the substrate and a second layer of catalytic material applied to the first layer; - Said enclosure having an inlet opening, communicating with the aforementioned exhaust orifice, through which the exhaust gases emitted by the engine are introduced into said enclosure to be passed there over the catalytic mass, then discharged into the atmosphere after passage through the exhaust pipe.

In general, the catalytic oxidation of carbon particles occurs at about 400 ° C, while the normal combustion temperatures for such particles are in the range of 700 to 800 ° C. For hydrocarbon particles. bures, catalytic oxidation occurs at temperatures of the order of 200 ° C.

We have studied the influence of the catalyst on the temperature at which the catalytic oxidation of particles entrained in the exhaust gas stream of a diesel engine occurs. A number of catalytic samples have been prepared. These catalysts are formed from a stainless steel wire 310 of 0.25 mm in diameter, rolled to the state of ribbon having a thickness of 0.01 mm, a layer 40 / of alumina and a layer of one or more metals from the platinum mine, .......

I employed in a proportion of the order of 2.46 mg / g of alumina, I A piece of this coated wire, as well as particles of material originating! exhaust gases from a diesel engine are subjected to the effects of an increasing temperature in the sample cuvette of a differential determination colorimeter (DSC) under an argon atmosphere containing 1% oxygen. Samples of the atmosphere above this cuvette are brought through a heated capillary tube to a mass spectrometer.

There are four mass values: carbon dioxide (44), double charge argon (20), oxygen (32) and water (18) or nitrogen and carbon monoxide (28).

The temperature at which the differential recording of DSC peaks is that at which combustion of the particles occurs.

This temperature can be considered as the "extinction" temperature. The results obtained are as follows:

Alumina load Metal or catalytic metal (s) Extinguishing temperature (g / g of wire) C ° C> 0.33 5.7% Rh 94.3% Pt 235 0.28, 67.0% Pt 33 .0% Pd 207 0.30 Pd 265 20 0.28 Pt 220 J The extinction temperature of the particles contained in the exhaust gases of a diesel engine is in the range of 207 to 265 ° C, which is very much lower than the combustion temperature obtained when no catalyst is present.

Since the presence of a catalyst makes it possible to oxidize the smoke-generating particles present in a gas, at a temperature much lower than the normal temperatures at which combustion would occur, it is therefore not necessary to provide heating. to carry out catalytic oxidation of smoke-generating particles in the exhaust gases of an internal combustion engine.

A, This is due to the fact that when the diesel engine is running between its

Medium power and its maximum power, its temperature is of the order of 400 ° C, and d ^ nc, no prior heating in contact with the exhaust gases of the engine with the catalyst is necessary.

The filamentous metal substrate can be in the form of a wire and is then in a form which ensures maximum contact of the catalytic metal with the exhaust gases. Preferably, the wire is in a flattened form, generally obtained by stretching prior to the deposition of the first layer and of the layer of catalytic metal.

4 i <«

In the operation of a diesel engine or the like, in which an excess of air or oxygen is present in the combustion chamber, it follows from the aforementioned contact that a substantial proportion of the pollutants as defined above undergo l 'catalytic oxidation.

A preferred arrangement of the wire-based substrate in the aforementioned chamber is to place it in such a way that turbulence is created in the effluent gases.

The subject of the present invention is a method of reducing the pollution due to the exhaust gases from internal combustion engines, which consists in passing the exhaust gases coming from the engine cylinders into an enclosure or chamber containing a fixed catalyst. on a support having a shape such that turbulence occurs in the gas flow, * and so that the pollutants present in the exhaust gases come into contact with the catalyst, and so that at least part of the particles and 15 harmful constituents present undergo catalytic oxidation.

Preferably, the engine is a diesel engine.

! The characteristics of internal combustion engines in accordance with the present invention are as follows: i) an enclosure or chamber comprising an external wall provided with a plurality of inlet openings intended to be connected with the orifices d 'exhaust of said engine and provided with an outlet opening into the gas exhaust duct; ii) a catalyst fixed on a support arranged so that the exhaust gases coming from the exhaust ports of the engine and circulating in said enclosure or chamber pass over the catalyst, this catalyst being arranged in such a way that the flow of the exhaust gas is a turbulent flow at least during the contact of said gas with the catalyst.

Preferably, the catalyst employed in connection with the internal combustion engine comprises: a) a divided substrate which is arranged in the path of the gas flow so as to create turbulence in the exhaust gas stream; b) a first layer of refractory metal oxide adhering to the substrate and disposed on the surface of the substrate; and c) a catalytic metal chosen from the group comprising: Ru, Rh, Pd, Ir,

Pt, Fe, Co, Ni, V, Cr, Mo, W, Y, Ce, or their alloys, as well as intermetallic compounds containing at least 20¾ by weight of one or; several of said metals arranged on the surface or in the mass of the first metal oxide layer.

. '5

The first refractory metal oxide layer preferably contains,

In the form of their oxides, one or more of the metals belonging to the list including Mg, Ca, Sr, Ba, Sc, Y, lanthanides, Ti, Zr, Hf, Th, Ta, V,

Cr, Mn, Co, Ni, B, Al, Si and Sn.

The first oxide layer is preferably formed from Al203 and alumina hydrates, although stabilizing oxides such as BaO and catalytic activity promoting oxides such as Ti02, Zr02, Hf02, Th02, Cr203 and NiO may also be present.

A preferred embodiment of the catalyst substrate according to the invention consists of a fabric or knitted structure obtained from a yarn and, more preferably, a fabric or knitted fabric obtained from a yarn having been stretched before manufacturing said fabric or knit. Suitable alloys capable of being used in the manufacture of the aforementioned wire are alloys of a base metal resistant to corrosion and more particularly to oxidation.

Examples of such base metal alloys are nickel and chromium alloys with an Ni + Cr aggregate content greater than 20¾ i by weight and iron alloys comprising at least one of the following elements (in weight proportions): 20 · Cr (3 to h0%), • Al (1 to $ 10), • Co (from traces to 5%), • Ni (from traces to $ 72), • C (from traces to 0.5¾).

25 Such substrates are described in German patent application No. 2,450,664. Other examples of base metal alloys capable of withstanding the rigorous conditions required are the iron-aluminum alloys, chromium, containing moreover 'yttrium. The latter type of alloy may contain (in weight proportions): 30 · Al: 0.5 to 12 $, "· · Y: 0.1 to 3.0 $,, '' · Cr: 0 to 20 $, • the rest consisting of iron.

Such types of alloys are described in US Pat. No. 3,298,826.

Another type of Fe-Cr-Al-Y alloy can comprise (in weight proportions): Al: 0.5 to h%,: Y: 0.5 to 3%,

Cr: $ 20.0-95, 'ψν

The latter type is described in U.S. Patent No.

3,027,252.

According to an embodiment of the invention, the base metal alloys can have a lower corrosion resistance, and therefore, for example, consist of mild steel, in which case the surface of the substrates must be coated with a protective coating composition, as described in British Patent Application No. 79-03 817.

When using wire as a substrate, its thickness should preferably be between 0.025 mm and 0.050 mm and, more particularly, between 0.025 mm and 0.030 mm.

According to an embodiment of the present invention, the catalyst is contained in a reaction zone which is arranged practically along the axis of the chamber. This embodiment is shown in Figure 1.

The outer wall 1 of the chamber has openings 7, 8, 9 and 10, which are in continuous relationship with the exhaust ports of the engine cylinders and further comprises an outlet 12 opening into the exhaust pipe 11.

The reaction zone 2, which is maintained in the chamber by means of the spacers 5 and 6, contains the supported catalyst 3. The reaction zone is arranged in such a way that the exhaust gases entering the chamber or enclosure must pass into the reaction zone, and therefore come into intimate and continuous contact with the catalyst before leaving the chamber and entering the exhaust pipe. The displacement of the exhaust gases can be indicated by the arrows F-, to F6-25 The combustion gases escaping from the engine cylinders via the exhaust orifices provided in the cylinders and the openings 7, 8 , 9 and 10, pass into the reaction zone 2, then leave this zone through the exhaust pipe 11. A retaining bar 4 is placed at the outlet of the reaction zone so that the catalytic mass remains in position.

The catalyst support is preferably a dense knitted fabric obtained from a thread. It can be in the form of a simple monolith or be * formed of annular elements.

The first oxide layer and the catalytic layer are applied separately to each element or after these elements have been joined together. According to another embodiment, the support, whether in the form of separate elements or connected together, can be coated with the two aforementioned layers after having been put in place in the reaction zone.

· # __ 7 /

Another embodiment is shown in Figure 2.

The external wall 21 of the catalyst chamber has openings 27, 28, 29 and 30, which are in continuous relationship with the exhaust orifices

Ides cylinders, and has an outlet 32 opening into the exhaust pipe 5 31. The catalyst 23 comprises a support, a first layer and a layer of catalytic metal arranged so that the exhaust gases entering the chamber containing the catalyst must pass over the catalytic mass before the exhaust gases leave the chamber and pass through the exhaust pipe. The exhaust gases circulate in the aforementioned chamber 10 in the direction indicated by the arrows F * 1s FUZi F * 3, and F ^ s.

These gases enter the chamber according to the arrows Fin, F / »3 and F ^, then pass over the catalytic mass, and finally leave the chamber through the outlet tube 22, as shown by arrow F45.

In this embodiment, the catalyst support is preferably a fabric obtained from a thread and formed into elements or as a single unit. If the support is in the form of elements, for example having a shape comparable to that of "donuts" (pets-de-nonne), these are generally joined together before the support is placed in the room. One end of the area containing the support is closed, for example by welding, using a disc 26, while at the other end an annular disc 25 keeps the support in position. The catalyst fixed on an apparatus is placed in the catalytic chamber as shown in FIG. 2, by fixing the ends, closed by the discs 25 and 26, to the external walls of the chamber.

To ensure that the support does not collapse, a perforated cylindrical outlet tube 22 is provided in the catalyst chamber, allowing the exhaust gases to pass and letting them escape through the exhaust pipe 31. The tube 22 can be formed from a dense metallic fabric or also from a metallic sleeve comprising perforations or holes.

Figure 3 shows an embodiment in which, instead of an axial cylindrical outlet tube, there is arranged in said chamber a series of five rigid bars, 100-500, arranged over the entire length of the chamber. These bars are arranged in positions fixed with respect to each other, so that the catalyst fixed on a support is held rigidly in place by means of the spacer plates 600. The spacer plates, placed in pairs, connect between them three of the five bars and generally form right angles to each other, that is to say are arranged I along a diameter of the axial cylindrical outlet tube.

/ 8 I It is possible to use two or more than two pairs of spacer plates, and they are generally arranged at regular intervals along the length of the chamber.

According to an embodiment of the invention, spacer plates can be used in place of rods where they have to be continuous over the entire length of the chamber, as shown in FIG. 4. Rods and spacers must be constructed of an oxidation resistant material up to a temperature of at least 800 ° C.

Another embodiment of the invention is shown in Figure 2A, in which, for simplicity, only two exhaust gas inlet openings have been shown. The outer wall 100 of the catalyst chamber has openings 101 and 102, in continuous relationship with the exhaust ports of the cylinders and has an outlet 103 opening into the exhaust pipe. The catalyst 104 is formed of a support, a first layer and a layer of catalytic metal and is arranged so that the exhaust gases have to pass over the catalyst before leaving the chamber. The catalyst is placed in the chamber containing spacer plates 105 as described above.

One end of the exhaust plates 109 is fixed to the wall 100 of the chamber, while the other end of the plates has a metal disc or plate placed in such a way that no trace of gas can leave the chamber without pass over the catalyst. The exhaust gas enters the chamber through the openings 101 and 102 and, after passing through the sleeves 106 and 107, passes into the internal space 110 formed by the space plates 105. The exhaust gases pass through the catalyst in a direction directed towards the outside, then leave the chamber by the exit 103. This direction of displacement of the exhaust gases is indicated by the arrows

Fso to Fί 09 1

The catalyst support is preferably obtained from a knitted fabric 30 formed in the form of four elements or three units.

If the support is formed of elements, for example elements having the appearance of donuts (pets-of-nun), these are generally linked together before! the support is not placed in the room.

Other advantages and characteristics of the present invention will appear on reading the following description and examples given by way of illustration but not limitation.

! v i ß EXAMPLE 1

In order to show the results to which the mode of operation according to the present invention leads, a multi-cylinder engine (having a capacity of 2000 cc) from a commercially available diesel engine automobile is used.

A catalysis chamber according to the first embodiment of the present invention (the one shown in Figure 1), is arranged on the engine. A catalyst support formed of stitches is knitted and produced from a yarn having the following composition: 10%, by weight

Cr .... 15 AL ..... 4 Y ____ 0.3

Fe .... in addition 15 0n is deposited on this support a first layer formed of gamma alumina, stabilized by 5% by weight of BaO, then a second layer consisting of a catalytic metal formed of platinum and palladium. The Pt / Pd ratio is 1/1, and the Pt + Pd charge, expressed relative to the total weight of the catalyst, is 2.5 g; the volume of catalytic mass used is 1344 cm3.

The results which are obtained are obtained by operating the engine according to the LA4 diesel cycle. The hydrocarbons, carbon monoxide, carbon oxides and particles present in the exhaust gases emitted are determined in g / mile, that is to say, in grams for 1.6 km.

Control tests, carried out for comparison, are carried out on the same apparatus without the chamber containing catalyst, the pressure difference being adjusted to the same value as that of the catalyst present.

The results obtained are recorded in the following Table I:

TABLE I

30 Hydrocarbons CO NOx Particles (g / 1.6 km) (g / 1 # 6 km) (g / 1f6 km) (g / 1r6 km) 'j Control tests ... 1/54 1.93 1.53 0 , 85

Engine modified. 0.214 1.892 0.979 0.44 35 --- j We see that the pressure difference is too high. 1 __ \ P. 10w

EXAMPLE 1A

Other tests are carried out on the same catalyst as that of Example 1, above. The emission of particles in the case of the control test using the same vehicle is carried out in four tests and expressed in 5 g / 1.6 km. Thermo-gravimetric determinations of the percentage of carbon and volatiles, as well as of the sulfate, in g / 1.6 km, contained in these particles are also carried out in these tests.

The results obtained are as follows:

. 10 WITNESSES

TEST Particles Percentage Percentage of carbonate volatiles * No. (g / 1.6 km) (g / 1.6 km) 15 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 LEGEND: All of the above measurements are made on a hot LAh operating cycle.

During these control tests, the content of hydrocarbons, CO and NOx is also determined, which leads to the following results: TEST Hydrocarbons CO NOx 25 No. (g / 1.6 km) (g / 1.6 km) (g / 1.6 km) 1 0.350 1.564 1.775 2 0.330 1.529 1.803 3 0.354 1.561 1.786 30

We build a catalytic chamber adapted to the constraints of the vehicle without modifying the engine outlet compartment.

This leads to a catalytic volume of 0.9 which has been planned not to be suitable but on which the tests have been performed.

35 The results obtained are as follows: -> · £ ”.

% N, .ψ /.

TEST Particles Percentage Percent Sulfate

Nn of carbon from volatiles

Cg / 1.6 km) (g / 1.6 km) 1 0.494 79.4 20.6 0.036 5 2 0.441 76.4 23.6 0.037 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 10 LEGEND: The vehicle has covered 800 km on the road prior to the first test and the total period of the test is completed under simulated conditions of city driving - on the ML cycle.

The cases obtained with regard to the hydrocarbon, CO and NOx content are as follows: TEST Hydrocarbons C0 NOx

No. (g / 1.6 km) (g / 1.6 km) (g / 1.6 km) 1 0.224 0.979 1.892 20 2 0.238 1.073 1.874 3 0.215 0.981 2014; EXAMPLE 2

A second catalytic chamber according to the second embodiment 25 (Figure 2) is fixed to the engine. A knitted mesh backing, obtained from the same yarn as that used in Example 1, coated with g? Mma alumina, is used. The catalytic metal layer is formed from rhodium (7.5% by weight) and platinum (92% by weight).

The total volume of the catalyst is 1760 cm3. The weight of the support used is approximately 1.6 kg and 5 g of alumina and 2.9 g of the catalyst metals are fixed thereto.

Rh and Pt in the above report. The control tests are carried out in the absence of a catalyst, the chamber however being fixed to the engine.

I The results obtained are recorded in Table II, below; they are j carried out under engine operating conditions according to the LA4 35 cycle operating with a hot start.

-r "i ** .- C

k / '12. ; y y · "''

TABLE IX

Hydrocarbons CO NOx Particles (g / 1.6 km) (g / 1.6 km) (g / 1.6 km) (g / 1.6 km) 5 ““

Control tests 0.35 1.55 1.8 0.57 »Modified engine 0.2 0.5 2.1 0.31

The pressure difference when no catalyst is present in the chamber is 6 cm of mercury, and 8.75 cm of mercury when the catalyst is present in the chamber. The atomic ratio C / H of the particles present in the exhaust gases, before and after passage through the catalytic chamber, is measured.

The results obtained are recorded in the following Table III, which corresponds to the case of a hot start of the engine.

TABLE III

♦ C / ll ratio of particles present in the exhaust gas *> 2q Before catalysis After catalysis C 63 80 H 37 20 25 This constitutes a measure of the reduction rate of the organic compound content of the exhaust gases. The sulphate concentration present in the exhaust gases before and after catalysis is also measured, and it can be seen that it is not modified.

Table IV below contains measurement results carried out under the same conditions as above but with a cold start of the engine.

J TABLE IV

i ----- - ------- - i- ----- -

Hydrocarbons CO NOx Particles (g / 1.6 km) (g / 1.6 km) (g / 1.6 km) (g / 1.6 km) 35 -------

Control tests 0.41 1.3 1.9 0.62

Engine modified 0.242 0.274 1.86 0.42

Engine modified 0.218 0.252 1.86 0.4. ·. ,, .... „jf; · -ΪχΓ ί ψ 13

The composition of the particles present in the exhaust gases is given in Table V, below, for a cold start of the engine.

TABLE V 5

Hydrocarbons

Carbon sulphates adsorbed (g / 1.6 km) (g / 1.6 km) (g / 1.6 km)

Control tests ... 0.11 0.34 0.165

Engine modified ... 0.11 0.28 0.025

The results recorded in Tables II, III, IV and V, above, are obtained on a diesel engine of a commercially available automobile. The engine was modified by adaptation of a catalysis chamber, as described above. The automobile is made to complete an 800 km circuit before operating it according to the taxi cycle, with a maximum speed of 40 km / h.

Other tests have been carried out on a commercially available automobile diesel engine. The catalysis chamber, similar to the second embodiment described in Figure 2, is fixed to the engine. The support is formed from a stainless steel wire 310, with a diameter of 0.25 mm, flattened to a thickness of 0.1 mm before knitting. The support is coated with a first layer of gamma alumina. The layer of catalytic metal is formed from rhodium (5.7%) and platinum (94.3%).

Expressed relative to the mass of the catalyst, the proportion of catalytic metal is 0.9 mg / cm 3. The weight of the wire used represents 3200g and the weight of the first layer is 1200g. The total volume of the catalyst used is 3472 cm3.

The weight of the particles present in the exhaust gas is determined by passing a known volume of exhaust gas through a dilution zone where it is diluted with a determined volume of air, in order to avoid solids do not precipitate before passing over a mass | 'filtering. The weight of the particles thus separated is expressed in g / h.

The particles present in the exhaust gases are further analyzed in order to obtain their thermogravimetric weight, and the weight of volatile constituents, hydrocarbons, carbon and sulphate present is also determined. Using the above method, one obtains a certain; number of filter media. The weight of sulphate contained in the particles is determined by wet chemical analysis.

- | i_

Another sample is placed in a thermogravimetric balance; the sample is heated under an inert atmosphere to a temperature of 780 ° C in order to obtain a constant weight. The weight loss between the initial weight and the new weight gives the proportion of volatile constituents present.

5 Air is then introduced into the enclosure and the heating is continued until the weight is again constant. The difference between this - weight and the previous constant weight gives the weight of carbon present.

The rest are ash and non-combustible materials such as iron.

The control tests are carried out by replacing the chamber containing the catalyst with a pipe connected to the engine. The tests are carried out on an engine operating under the following conditions: - LA4 diesel cycle cold start - Table VI.

- Cold start LA4 diesel cycle - Table VII. · * 15 —Function test on highway - Table VIII. - The highway test used is the standard cycle used in the United States for fuel consumption tests.

The results recorded in Tables VI and VII "below, are represented by graphs in FIGS. 5 to 9, for the LA4 cycle with cold start jet in FIGS. 10 to 14, for the LA4 cycle with start at hot. (The curves corresponding to the control tests are shown in dotted lines, while the tests carried out on the modified engine are shown in solid lines).

The reduction in the particle concentration (determined in g / 1.6 km) in an IC engine according to the present invention is shown in column 3. The reduction in carbon and adsorbed hydrocarbons present in the particles is shown in the columns 7 and 9, respectively.

The column for sulphate shows an increase in some cases, but the absolute level of emission remains very low.

30 . The measurement of the pressure difference is determined. This is the difference between the pressure of the gases at the exhaust port of the cylinders and when they leave the chamber.

The results are recorded in Table IX, below, which corresponds to the case where the engine operates according to the LA4 cycle, and in Table X, also below, in the case where the engine operates according to the said test. "on highway". - i i 1 *

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Return pressure in centimeters of mercury

Kms Control test After passage ___on catalyst 10 covers maximum average maximum average.

Hot start 0 7.80 1.58 7.20 1.88 2 880 8.55 2.50 ^ 6 720 9.50 2.45 7 840 * 9.18 2.28 8 800 13.38 4.75 9.760 6.05 1.63 11.45 3.57 13,600 8.27 2.40 20 20,000 5.95 2.13 Cold start 0 6.60 1.20 8.85 2.15 25 2,880 7 .88 2.87 6,720 11.50 2.40 7,840 11.25 2.38 8,800 12.15 4.13 9,760 12.10 * 1.53 11.55 3.45 30 13,600 8.20 2.40 20,000 6.25 2.08 t 'ic / High value probably due to the formation of 35 y soot deposits.

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PAINTINGS

Return pressure in centimeters of mercury 10 -

Kms _. , ^. After passage. Control test 2 t covered on catalyst maximum average maximum average 2,280 8.35. 4.95 15 9,760 5.0 2.75 10.13 7.25 13,600 7.80 5.00 »20

TABLE XI

25

Return pressure in centimeters of mercury

Control test After covered passage 2, on catalyst maximum average maximum average 30 ----- 0 7.2 1.40 8.00 2.00 13,600 11.2 1.53 11.55 3.45 4

W

In the above description, the following abbreviations have been used, and their meaning is given below: CVS = sample of constant volume.

LA4 = Cycle called Los Angeles as defined by the Environmental Protection Agency (EPA) and the United States.

This is a standard witness cycle, intended to simulate driving under traffic operating conditions in Los Angeles.

It is actually a test to which all new vehicles are subjected.

10 Taxi Cycle = Control cycle of approximately 80 km long, approved by the Environmental Protection Agency, carried out at a slow speed, of the order of OU km / h. It includes periods during which »the vehicle is stationary and the engine is idling.

Of course, the present invention is in no way limited to the examples and modes of implementation mentioned above; it is susceptible of numerous variants accessible to those skilled in the art, according to the applications envisaged and without qqe one does not depart from the spirit of the invention.

D-v.

i Γ »4- i i j i î i

Claims (14)

1. Internal combustion engine comprising means for reducing the pollutants contained in the exhaust gases produced by engines comprising at least one exhaust orifice, these means comprising a casing 5 defining an enclosure or chamber containing a catalyst, this catalyst being formed of a substrate made of a filamentary metallic material, woven, knitted or ground, of a first layer of a refractory metal oxide fixed on the substrate and of a second layer of catalytic material applied to said first layer, said enclosure further comprising an inlet opening communicating with the aforementioned exhaust orifice through which the exhaust gases emitted by the engine are introduced into * said enclosure in order to be passed thereon over the catalytic mass prior to their release into the atmosphere after passage through the exhaust system. 2. Engine according to claim 1, characterized in that the casing 15 comprises a number of openings corresponding to the number of exhaust ports of the engine. 3. Engine according to 'claim 1 or 2, characterized in that said means are arranged opposite the engine exhaust orifices. 4. Engine according to any one of claims 1 to 3, characterized in that the metal substrate is arranged so as to establish maximum contact between the catalytic material and the exhaust gases. 5. Engine according to any one of claims 1 to 4, characterized in that the catalytic material is a metal or metal alloy or a composition containing two or more metals and / or oxides of these metals. 6. Motor according to claim 1, characterized in that the metal substrate is in the form of a strip having at least two opposite planar faces. 7, - Motor according to claim 1, characterized in that the metallic filamentary material is in the form of a wire. 8. An engine according to any one of claims 1 to 7, characterized in that the metal substrate is arranged so as to cause turbulence in the flow of the exhaust gases leaving the chamber. 9.- Motor according to any one of claims 1 to 8, characterized in that the refractory metal oxide layer is chosen from the group comprising: Mg, Ca, Sr, Ba, Sc, Y, lanthanides, Ti, Zr , Hf, Th, | Ta, V, Cr, Mn, Co, Ni, B, Al, Si and Sn. i> I -ft r- 10. Engine according to claim 9, characterized in that the first layer is formed of at least one of the following constituents: Alz03, alumina hydrates, BaO, Ti02, Zr02, Hf02, Th02 or Cr203. 11. Motor according to claim 1, characterized in that the substrate 5 is formed from a corrosion-resistant alloy containing a base metal. 12. Motor according to claim 11, characterized in that the substrate is formed from an alloy containing nickel and chromium, comprising a content of nickel plus chromium aggregate greater than 20% by weight. 13. Motor according to claim 12, characterized in that the substrate 10 is formed from an iron alloy comprising at least one of the following elements, the content of which is expressed in weight proportions: ^ · chromium - 1 to 1 * 0% • aluminum = 1 to 10% • cohalt = traces up to 5% 15. nickel = traces up to 72% • carbon = traces up to 0.5%. s 14. Engine according to claim 15, characterized in that the base metal alloy comprises yttrium in a proportion of the order of 0.1 to 3.0% by weight. 15. An engine according to claim 1, characterized in that the substrate is formed of a metallic material having a thickness of between 0.025 mm and 0.05 mm. 16. Engine according to any one of claims 1 to 15, characterized in that the catalytic material is a metal chosen from the group comprising: Ru, Rh, Pd, Ir, Pt, Fe, Co, Ni, V , Cr, Mo, W, Y, Ce, as well as alloys containing at least one of said metals and intermetallic compounds containing at least 20% by weight of one or more of said metals. 17. Internal combustion engine according to any one of claims w 1 to 16 operating according to the diesel combustion cycle. r 30 18.- Method for reducing pollutants contained in exhaust gases from internal combustion engines, which consists in passing said exhaust gases from the cylinders of said engines into a chamber containing a catalyst fixed on a support having a configuration such that turbulence is created in the gas flow, and in that the pollutants present in the exhaust gases come into contact with said catalyst, and in that at least some of the particles of harmful constituents undergoes catalytic oxidation. ---- t "