FR2789119A1 - Purification of exhaust gases from motor vehicles comprises combining effects of conventional three-way catalysts with catalyst comprising powdered calcium carbonate - Google Patents

Abstract

The presence of powered calcium carbonate supplements the action of a conventional three-way catalyst, which is ineffective until it reaches 200-300 deg C. In the purification of motor vehicle exhaust gases, the gases, directly after engine start-up, are simultaneously submitted to the three-way catalysts and to dissociated powdered calcium carbonate (CaCO3). The gases initially pass through the three-way catalyst and then through the reactor containing the CaCO3 powder. An Independent claim is also included for a reactor unit, containing CaCO3 powder, attached to the exhaust system.

Description

The whole world is trying to eliminate pollution

  atmospheric automotive.

  The catalyst "3 ways" has brought here only an imperfect solution, but which can be improved, Here is how: In the French patent N 98.10515, filed on August 18, 1998 in the name of the inventor of the present, we

  have described a process for purifying exhaust gases

  motor vehicles, consisting in putting these

  gas in contact with calcium carbonate (CaCO3).

  Then applying this process, we have, in the French patent N 98.14021 filed, the 6

  November 1998, still on behalf of the inventor of the pre-

  sentes, describes an exhaust gas purifier

  motor vehicles based on calcium carbonate pulp

verified (CaC03).

  In doing so, we aimed to neutralize after the fact, the pollution caused by vehicles that turn out

be polluting after use.

  Currently, we plan to neutralize the pollution (atmospheric in particular) caused by new vehicles leaving the factory; in other words from

  complete the concomitant exhaust gas cleaning

  ment with the purification carried out by the catalytic converter.

  There is a simultaneous and complementary treatment

  based on pulverized calcium carbonate.

  It is a process which relates more precisely to the

  manufacture of vehicles fitted with an internal combustion engine

s ions.

  That said, it should be remembered that the cataly-

  tick, as it is currently manufactured to equip motor vehicles, is the result of a technique

developed year after year.

  Briefly, we will recall that the catalysis of

  exhaust from internal combustion engines has been progress-

  significantly improved: - one way: reduction of nitrogen oxides: NO - two ways: "carbon oxides: CO and nitrogen: NO (double catalysis) - three ways: simultaneous elimination of CO, NO and HC

  (unburned hydrocarbons associated with metal oxides-

  liques) with, however, the need for permanent control to avoid sometimes excess air, sometimes excess fuel, if we do not want to see decrease

the efficiency of the catalyst.

  There can be no question of modifying the "3-way" catalysis, that is to say modifying the catalytic converter with which motor vehicles leaving the factory are currently fitted. The present invention preserves the catalytic converter

  as it is. But as it stands, even with

  simultaneous CO, NO, and HC, the catalytic converter

  generates air pollution which becomes worried-

  aunt, especially in the cities: so much so that in France, at the dawn of the year 1999, The Government, envisaging, the years to come the construction of the motor vehicles operating with the

  hydrocarbons (petrol and diesel), recommends the growth

sance Zero.

  so much so that the governments of several countries are reduced to limiting the circulation of vehicles fitted with internal combustion engines in cities reputed to be very polluting like Mexico, Jakarta,

  Tehran, Rome (to name just a few).

  It is therefore necessary to examine how, by preserving the 3-way catalysis, it would be possible to neutralize the atmospheric pollution which it generates,

especially in the cities.

  This brings us to highlight the weak points of this catalysis and to examine if it is not possible

to remedy it.

  Two observations are essential: 1 / The 3-way catalytic converter undergoes wear during use

  which makes him lose his performance.

  2 / This catalytic converter has no action on pollutants, as long as it has not reached a minimum temperature of 200 to 300 C, which requires approximately 2 minutes (120 seconds). In other words, the priming of the catalysts is too

long: about 120 seconds.

  We will not dwell on the mechanisms which

  are at the origin of the loss of performance of the cat-

lysers.

These mechanisms are known.

  Just remember that they can be of origin: - chemical: poisoning - mechanical: thermal shock, attrition - thermal: sintering, alloys, oxidations

  - or the series of secondary reactions: fouling -

carbon deposit.

  All without mentioning the necessary vigilance perma-

  nente to avoid sometimes the excess air, sometimes the excess

  of fuel, if you don't want the efficiency to decrease

catalyst efficiency.

  On the other hand, the initiation time of the catalysts requires a development which we will proceed below. In view of what has just been said, we will conclude by saying that:

"THE IDEAL CATALYST WOULD BE THE ONE

  "- which cannot be reached by any of the mechanisms

"above.

  "- which would absorb the same toxic gases as the" 3-way catalyst with zero priming time

  "- which would, moreover, on man and the environment-

"beneficial effects.

  This seems to be the case with calcium carbonate

sprayed.

  To convince ourselves of this, let's examine, one by one

  each of the 4 proposals made.

1 / Deactivation mechanisms

  The dissociation of pulverized calcium carbonate

  risé works here like a fluid bed catalysis

  said, in which the catalyst takes the form of a suspension of powder floating in the fluid containing

the gases to be treated.

  As it is, it doesn't seem like it can be

  affected by any of the above mechanisms.

  2 / Absorption of the same toxic gases

  The 3-way catalyst allows the elimination almost

  complete with the 3 regulated pollutants: - carbon monoxide: CO - "nitrogen: NO - HC, that is to say the unburned hydrocarbons mixed with metallic oxides,

  with, as we have said, requires permanent control

  to prevent excess air, sometimes excess fuel which could affect the efficiency of the cat-

  lyser and generate parasitic ammonia formation.

  Calcium carbonate, known for over a century in chemistry, absorbs, during its dissociation,

  the 3 aforementioned pollutants: CO, NO and HC, with this

  sion that this absorption concerns the metal oxides which, associated with unburned fuels, form precisely what is customary to designate under the

term for: "HC".

  But to what extent are the unburned hydrocarbons toxic when the metal oxides with which they are associated in the exhaust gases are absorbed by calcium carbonate? NH3 atmospheric ammonia is a source

  significant indirect nitrogen oxides.

  Its origin, in particular, the spreading of

  manure and animal droppings; but also, it is necessary

  to say it, a possible adjustment of the cataly-

  ticks. However, it is worth pointing out that from 460 to 490 C, the ammonia is absorbed by the carbonate

calcium.

3 - Priming time

  Therein lies the main weakness of the cat-

  3-way lyser and o a catalyst, such as pulverized calcium carbonate, could compensate for this weakness by operating simultaneously and in a way, in a way, complementary. In fact, the 3-way catalyst, to be effective, must reach, we have said, a temperature of at 300 C, which requires approximately 2 minutes after

starting the engine.

  And during these two minutes, what's going on?

  To realize this, you have to consider a vehicle

  It starts in the city and only circulates in the city, because it is in the city that the air pollution is located first. According to statistics, the duration of the urban journey for each vehicle is, on average, 13 minutes, 13 minutes during which the 3-way catalyst does not

remains inactive for only 2 minutes.

  And during these 2 minutes, the statistics indicate that the pollution generated is:

- CO: 50%

-NO: 50%

- HC: 75%

  taking as a basis the total pollution generated

  during the entire race which lasted 13 minutes.

  We are therefore necessarily led to envisage a second catalysis, supplementing the first, the catalyst of which would be operating the first 2 minutes when the 3-way catalytic converter does not yet work.

  This is especially the object of the present invention.

  Add that outside of the 2 minutes of priming, the

  pulverized calcium carbonate may also, if necessary,

  also replace the catalytic converter with one

  deactivation mechanisms envisaged above.

  But all this supposes that the pulverized calcium carbonate is effective, for its part, well before the 2

  minutes after the engine is started.

  To be precise, how many seconds will it take

  wait to see the dissociation of the carbo-

  calcium nate in the presence of CO, NO, and HC, from the start of the engine?

  As soon as the engine starts, the gases come out of the collar.

  reader at a temperature of 900 to 1000 C, then exit into the air at a temperature of around 400 C. This decrease in temperature is the consequence of

  heat transfers to the wall of the exhaust circuit

  at the distance between the exhaust manifold

  and the characteristics of the pot

  itself (thermal insulation and conductivity).

  Taking into account what has just been said and the place of the reactor (attached figure) on the exhaust pipe, the dissociation temperature of the CaCO 3 powder,

  550 'C, will be reached in about 10 seconds, access

  operating the engine in neutral for about 10 seconds will not be essential (to cause

  "thermal shock", but only desirable.

  But how was this temperature of 550 C necessary for the dissociation of CaC03 deduced? The only elements in the possession of the inventor are chemical analyzes dating from the last century, made in laboratories, on CaC03, not sprayed,

but crushed.

  These analyzes all indicate that the dissociation of CaCO3, in the presence of CO and NO, begins at 600, but that this temperature can be lowered using an adjuvant such as: - NaCl: sodium chloride (salt) - or CaCl "" I calcium

  one or the other, 1 to 2%.

  The authors add, however, that this temperature

  erection of 600 is a function of: - the heating rate, - the crystallization state of CaCO3,

- and the mass of CaCO3.

  They also specify that water vapor can be considered as a second adjuvant coming to combine

with the one chosen.

  However, here, it should be noted that the exhaust gases contain 10 to 12% of water vapor. As for the metal oxides absorbed by CaC03 (mixed here with unburned hydrocarbons), all of the above analyzes indicate that calcium carbonate

  reacts in their presence at very low temperatures

higher than the above-mentioned 600 C.

  For completeness, it should be noted that the pulverized calcium carbonate used here is a very fine powder, the grains of which have an average diameter of 1.7 t i, and that we can therefore consider them as aerosols

  potentially removed from the law of gravity.

  4 - Beneficial effects on man and the environment-

  ment of pulverized CaC03 whose grains can become aerosols We know the harmful effects on man and his environment of the polluting gases spread by the engines

  explosions (air pollution in particular).

  On the other hand, we see less of the beneficial effects of the calcium carbonate particles, which are widespread in

air in the form of aerosols.

  At the start of his experiment, an invention new

  velle never masters all the effects it produces,

  especially in the area of exhaust gases.

  It will therefore be possible that an incorrect setting will cause the particles of CaCO3 to be suspended in the ejected residual gases. What would be the consequences ?

- On visibility.

  The particles being, by hypothesis, of an average diameter

  1.7 [1This will be a haze (not a haze-

  bacon) disturbing the atmosphere and reducing the visibility

  bility without lowering it below 1 km.

  Note, however, that this drawback disappears

  line using a finer powder (average grain diameter 0.10 P1n /), because then the powder grains having become transparent, will no longer diffuse the

  light by a cloudy suspension.

- On the environment...

  CaC03 sprayed can only have a beneficial effect.

  plants that have a calcium content of

1 to 2 %.

  Besides, isn't calcium carbide CaC2 already used in composition as a nitrogen fertilizer?

On men.

  The calcium element is essential for life.

  By breathing in aerosols for a period of time,

  holding this fine powder of CaC03, we will find this

substance in the blood.

  It should be noted however that the filter cartridge (which we will describe below) will mainly have the function of purifying the gases at start-up, these must then be purified by the catalytic converter. As a result, powder consumption will be low

and the small cartridge.

D E S C R I P T I 0 N

  The device for implementing the method

  sistant to combine the effects of the 3-way catalyst

  with those of the pulverized calcium carbonate is schematic

  tiser on the single figure attached to this patent.

  This figure has 4 elements: 1 - A metal reactor in which the chemical reactions will take place leading to the elimination of toxic gases: in the figure, it takes the form of the small cylinder MKJH, a kind of sleeve in which the gases of exhaust arrive at G and the residual gases are expelled at X. As we can see in the figure, this reactor is incorporated into the vehicle's exhaust pipe, but is located downstream of the catalytic converter, that is to say between the latter and the release of gases into the air, because

  exhaust gases are purged first by the catalytic converter

  lytic. 2 - A filter cartridge comprising at the head an endless screw (A) and topped with a plug P This cartridge is introduced into a metal sheath (C) whose role is twofold:

  5. keep the cartridge in an upright position and

  pendulum to the direction of the exhaust gas fluid

  is lying. serve as a regulator for the intensity of the powder grains pulsed by the gases. To this end, it has an endless screw internally adapting to that (A)

cartridge.

  This sheath is integral with the reactor on which it is fixed. It occupies the QTSF space by entering the reactor in ZDA inside this sheath, the cartridge occupies the EBUVNO space being specified that: the part of the EBNO cartridge is a metal cylinder to which is attached a screened part BUVN (meshes from 2 to 3 mm) on the side) 0 3 - a separating filter (LI) in mesh (mesh of 2 to 3 mm on the side) or in perforated sheet (openings of 2 to 3 mm in diameter occupies the entire surface of the cut of the cylinder in LI 4 - A gas compression chamber occupies the entire volume MLIH Add that the LKJI part can be designed to be removable and serve as a purification valve (as provided for in said patent N 98.14021) to remove soot and exposed sediments

F 0 N C T I 0 N N E M E N T

  The exhaust gases are purified 2 times: - first by the 3-way catalytic converter

  - then by the reactor operating with pulverized CaCO3 -

laughed.

  The catalytic converter and the reactor operate simul-

temporarily and are complementary.

  The filter cartridge is first fitted with a

  tction containing the powder of (CaCO3) added with an adjuvant (salt) intended to lower the temperature of

dissociation.

  It should be noted that this CaC03 powder used is very fine: average grain diameter: 1.7 Fk 11) which has the consequence of preventing the powder from spontaneously leaving the mesh of the cartridge. In fact, the grains are removed from gravity; but, on the other hand, they remain subject to the force of gravitation: the grains attract and no longer pass spontaneously through the meshes of the cartridge from which they are not extracted

only by the gas blast.

  Consequence: if the engine stops, the gas blast too and the cartridge does not empty. In other words,

  the cartridge only empties when the engine is running.

  Chronologically, here is how it goes: Open the trunk. The filter cartridge is engaged

in its sheath vertically.

  Given the risk of fire and explosion resulting from the confusion by a pump attendant of the fuel tank pipe with the sheath of the filter cartridge, it was prudent to impose the opening of the trunk to gain access to

the cartridge.

Remove the cap from the cartridge.

  Introduce the aforementioned packaging.

Recap the cartridge.

Start the engine.

  Accelerate 10 seconds to neutral for provo-

  quer the "thermal shock" of the dissociation of the powder

  of CaCO3 absorbing toxic gases, CO and NO in particular.

And then of 2 things one:

  or the residual gases exit the exhaust pipe-

  without any powder suspension.

  The toxic gases have been eliminated in whole or in

big party.

  or the residual gases leave the exhaust pipe

  pement with suspended particles of powder: the mixture is too rich in powder and these particles become aerosols without danger, but which can cause, not some fog (the particles have, by hypothesis, an average diameter of 1, 7 h M and are too fine), but a little haze not disturbing

  visibility and disappearing very quickly with the wind.

  This particle formation disappears in action-

  the worm (A) which will make more or less

  concentrated powder the powder-exhaust gas mixture

  is lying. In fact, the gases exit at G. Their breath pulses the CaC03 powder outside the T U V S grid,

the cartridge.

  The gases mix with the powder, compress

  and finally pass through the separator filter (LI).

  Finally, let’s add that the device is inexpensive and the same applies to the consumption of

powder.

-'- / 7

Claims (2)

R E V E N D I C A T I 0 N S   1 - Process for purifying vehicle exhaust gases   motor vehicles, characterized in that it consists of   simultaneously put the gases to be purified and the 3-way catalysis and the dissociation phenomenon of the pulverized CaCO3 at the start of the engine, but in such a way that the fluid containing the gases to be treated passes first into the 3-way catalyst and only then, in the reactor containing the powder of (CaC03) O10 2 - Device for carrying out the method according to claim 1, characterized in that the purification, carried out by means of the phenomenon of dissociation of the pulverized CaCO3, has using a metal reactor containing:! 15 - pulverized calcium carbonate (CaCO3) - a filter cartridge loaded with CaCO3 powder - a gas compression chamber - and a filter-separator - Device according to claim 2, characterized in that the CaCO 3 powder used optionally contains an adjuvant (such as sodium chloride (NaCl) or calcium chloride (CaCl) to the effect of lowering the temperature of dissociation of the CaCO3 powder 4 - Device according to claim 2, characterized in that the powder used is very fine and that the average grain diameter (1.7 / t)   can help turn them into aerosols.   5 '- Device according to claim 2, characterized in that the reactor is incorporated in the vehicle exhaust pipe and receives the gases   already treated by the 3-way catalyst.   6 - Device according to claim 2, characterized in that the filter cartridge: has a cylindrical shape suitable for receiving the   CaCO3 refills, in the form of packaging.   has a sheath intended to hold it in one position specific to its destination.   15. Has an endless screw to vary its insertion into the reactor and thus have a role of   CaCO3 powder flow regulator.   - Device according to claim 2, characterized in that the filter-separator is made of metal and consists either of a mesh (meshes of 2 to 3 mm per side) or of a perforated sheet (circular openings of 2 to 3 mm in diameter). Its function, as its name suggests, is to separate the grains of powder   still adhering to the treated toxic gases.   8 - Device according to claim 2, characterized in that the filter cartridge comprises a part in non-perforated sheet and a part in mesh or perforated sheet (intended to be exposed to the blast of exhaust gases) susceptible,   receiving the gases, letting them pass with the   cules of powder which they pulsate, it being understood that the grains of powder with an average diameter of 17 V do not pass spontaneously (without the aid of the gas blast) through meshes of 2 to 3 mm on the side or openings   circular sheets 2 to 3 mm in diameter.   9 - Device according to claims 3 and 4,   characterized by the fact that the CaCO3 powder intended   to fill the cartridge is delivered in doses or condition-   all prepared in paper bags whose shape and dimensions allow their immediate introduction in the cartridge.   - Device according to claim 2, characterized in that the reactor can be divided into two parts detachable from one another, then allowing the reactor to be purged of the soot and sediments deposited.