EP0543477B1 - Process for the addition of ferrocene to fuels or to petrol - Google Patents

Abstract

In this process for the addition of ferrocene to fuels or to petrols, improved metering of the ferrocene additive into the combustion chamber of an internal combustion engine or combustion installation is to be made possible. For this purpose, the sublimation properties of ferrocene are exploited by transferring the latter by means of sublimation into a stream of the combustion gas or a part stream thereof and feeding it together with the fuel or petrol present in fine distribution as solid or liquid particles or in the vaporised form to the chemical conversion by combustion. A preferred application is the charging of the combustion chamber of a diesel engine fitted with a diesel particle filter by means of a carrier gas stream enriched with ferrocene vapour in a sublimator.

Description

The invention relates to a method for the additive of fuels with ferrocene for the improved combustion thereof with atmospheric oxygen or gases containing oxygen.

To reduce fuel or fuel consumption and to reduce emissions from the combustion of fuels and to remove or reduce the carbon deposits in the operation of motor vehicle engines, liquid hydrocarbon mixtures consisting essentially of gasoline and an organometallic compound from the group of [bis (η-cyclopentadienyl) iron], hereinafter referred to as ferrocene, and gasoline-soluble derivatives of ferrocene have been proposed, cf. DE-OS 25 02 307.

Furthermore, the use of a liquid fuel with an addition of 1 to 100 ppm by weight of ferrocene has been proposed for the purpose of reducing fuel consumption and exhaust gas emissions in a gasoline engine equipped with an exhaust gas catalyst system for exhaust gas afterburning, cf. DE 38 01 947 A1. EP-A-0375303 also teaches the addition of ferrocene to diesel fuels.

BE-A-767834 teaches loading a mixture of a combustion gas with a vaporous catalytic organometallic compound.

In order to avoid an inadmissibly high exhaust gas back pressure when operating a diesel engine equipped with a particle filter in the exhaust gas stream, an engine lubricating oil additized with a catalytically active content in an amount of 5 to 20,000 ppm of an iron compound has been proposed for use. Ferrocene was considered as an iron compound, cf. DE 38 09 307 A1.

In an older German patent application P 41 29 408, a device and a method for the direct solid additivation of liquid fuels with ferrocene have been proposed. in which ferrocene is added to the liquid fuel in a metered amount by grinding ferrocene pellets.

All of these methods have in common that here an additive of the liquid fuel or fuel, z. B. heating oil, taking advantage of the solubility properties of the additive used, here ferrocene or ferrocene derivatives. The same applies to the additive of the engine lubricating oil, which can be done by direct dissolution or by means of the production of concentrated solutions in solvents compatible with the engine lubricating oil and their addition to the lubricating oil.

The production of corresponding solutions or stock solutions is cumbersome and complex due to the required dosing and mixing devices and the associated work steps. In addition, additional measures are required to ensure the stability and the specified properties of the fuels or fuels additized with ferrocene or ferrocene derivatives. This form of metering also has the disadvantage that the additives can only be optimized for a certain operating point.

The task is derived from this to enable an improved metering of the additive ferrocene into the combustion chamber of an internal combustion engine or an oil heater without prior addition as a solid or as a stock solution to the fuel, fuel or lubricant.

The object is achieved in that vaporous ferrocene is converted into a stream of the combustion gas or a partial stream of the same by sublimation and is fed to the chemical reaction by combustion with the fuel or fuel present in fine distribution as solid or liquid particles or in evaporated form. The advantageous solution to the problem is based on the utilization of the sublimation properties of ferrocene.

This measure offers the advantage that the amount of ferrocene can be easily adapted to the optimally required amounts for the individual different operating states of the internal combustion engine by means of control measures.

The compacts or pellets produced from ferrocene crystals preferably have dimensions of 1 to 10 mm and are subjected to a carrier gas stream of the combustion gas or of parts of the combustion gas in a sublimator at values of pressure and temperature in the region of the boundary or coexistence line between solid and gaseous phase . From there, the carrier gas stream containing ferrocene is fed further into the combustion chamber.

Ferrocene is a substance that, depending on the production method, is obtained in the form of yellow-orange needles. Some chemical and physical data are summarized below: formula Fe (C₅H₅) ₂ molar mass 186.04 g / mol density 1.49 g / cm³ Melting point 173 ° C boiling point 249 ° C 1.035 bar Shrivel point 183 ° C Vapor pressure 0.066 mbar 40 ° C 3.4 mbar 100 ° C Heat of fusion 17.8 kJ / g mol 175 ° C Heat of vaporization 47.2 kJ / g mol 175 ° C Heat of sublimation 70.2 kJ / g mol 25 ° C Decomposition point 465 ° C Magnetic susceptibility diamagnetic

In Römpps-Chemielexikon, 9th edition, volume 2, page 1330, it is stated under the keyword ferrocene that this sublimes above 100 ° C.

However, it was surprisingly found that even at temperatures below 100 ° C., sufficient amounts of ferrocene pass into a carrier gas stream in a suitable sublimator. When the carrier gas stream containing ferrocene is introduced into the combustion chamber for the intended combustion of the fuels with atmospheric oxygen or gases containing oxygen, effects are shown which are better or as good as the effects of the additive in the liquid fuel itself.

Moldings made of technically produced ferrocene such as pellets, pressed pieces or chips with dimensions of 1 to 10 mm can advantageously be placed in a suitable container of the sublimator. The ferrocene compacts can be produced from solvent-moist ferrocene crystals originating from a crystallization solution, for example ethanol-moist (purity at least 98.5% by weight) without the addition of binders or the like.

However, it is also possible to provide technically produced ferrocene without prior compression into molded parts in appropriately provided inserts, such as filter cartridges or the like, of the air filter for the combustion air of heating devices or motor vehicle engines which are permeable to the ferrocene vapor.

Depending on the desired concentration of the ferrocene converted into the carrier gas stream by sublimation, a preheating or preheating of the combustion air acting as carrier gas stream to a temperature of 20 to 175, preferably 50 to 150 ° C. can be provided.

Without additional heating, the operating states of the sublimator, depending on its structural integration in the engine compartment or in a burner adjacent to a heating device, can vary from around minus 40 ° C in cold outside temperatures and an unprotected location to plus 150 ° C with appropriate heating by the burner or Engine operation result. Of course, it is also possible to provide additional heating for the sublimator, which helps to even out the operating behavior even when starting up.

The pressure prevailing in the sublimator due to the pressure of the carrier gas stream is preferably between 100 mbar and 3 bar.

The pressure and temperature conditions as well as the geometric dimensions of the sublimator and the amount of carrier gas can be predetermined so that an evaporated amount of ferrocene of 0.1 to 1,000, preferably 1 to 100 mg per kg of fuel or fuel is obtained.

A preferred mode of operation is that the carrier gas stream is preheated to a temperature of 20 to 175, preferably 50 to 150 ° C.

One application of the present method relates to the introduction of a carrier gas stream containing ferrocene into the combustion chamber of a diesel engine. The diesel engine can be equipped on the exhaust side with a particle filter for retaining carbon-containing particles contained in the exhaust gas, referred to by the person skilled in the art as soot particles, which originate from an imperfect combustion of the diesel fuel with the combustion air in the engine.

An arrangement in which the carrier gas stream is fed from the intake air line and is passed via the sublimator, which is fed with compacts from ferrocene and integrated in a motor vehicle engine, is shown in FIG.

In this arrangement, the sublimator is arranged on the upstream side of the air filter for the combustion air sucked in by the diesel engine. As usual, the crankcase ventilation is connected downstream of the air filter to the line of the combustion air. Points 1 and 2 designate the measuring point for the temperature in the sublimator or the temperature and the pressure upstream of the diesel particle filter.

Another variant of the introduction of ferrocene is shown in FIG. 2.

The arrangements of Figures 1 and 2 are further designed so that the carrier gas stream branches off from the intake air line provided in each motor vehicle engine or from the crankcase ventilation and from there into the sublimator charged with ferrocene pellets so that a sublimator is introduced into the selected one Pressure and temperature conditions, the most complete possible transition of the ferrocene vapor into the carrier vapor stream is effected. From the sublimator, the ferrocene-laden carrier gas stream is combined with the necessary amount of intake air on the downstream side by an intake air filter while avoiding condensation and fed to the combustion chamber of the engine. The exhaust gas from the fuel combustion is released into the atmosphere on the downstream side of the engine via the particle filter and a silencer.

Points 1 and 2 each designate measuring points for the temperature in the sublimator or for the temperature and the pressure before the combustion exhaust gases enter the particle filter.

The results obtained with such an arrangement, namely a sublimator filled with ferrocene pellets in the crankcase ventilation, with regard to the combustion behavior of the diesel particle filter, are shown in a long-term test carried out over 20 hours in the graphic according to FIG. 3.

In these tests, a diesel fuel (clear) was used in accordance with the DIN specification (summer quality) with the following characteristics: sulfur G.-% 0.19 Density 15 ° C kg / m³ 839.9 Flash point ° C 65 Cloud point ° C 2nd CFPP ° C -5 Cetane number 52.2 Siedelage Start of boiling ° C 163 5% ° C 189 10% ° C 204 20% ° C 225 30% ° C 245 40% ° C 262 50% ° C 278 60% ° C 293 70% ° C 310 80% ° C 328 90% ° C 353 95% ° C 370 End of boiling ° C 380 yield Vol .-% 99 Beg.-250 ° C Vol .-% 33 Beg.-350 ° C Vol .-% 89 used and the test engine operated with combustion air additized via the crankcase ventilation. The lubricating oil used belonged to class SAE 15 W 40.

The test engine was a model of the make Opel 2.3 1 passenger car diesel, naturally aspirated with a swirl chamber combustion process and a nominal output of 54 kw.

The engine was operated at 2,000 rpm and a load of 28 Nm torque (partial load). The temperature in the sublimator was approximately 40 ° C. In the diagram in FIG. 3, the dotted curve denotes the measured values of the temperature at the measuring point 2 upstream of the diesel particle filter. The solid sawtooth-like curve shows the course of the pressure on the upstream side of the diesel particle filter.

The pressure initially increased from about 80 to 350 mbar due to the deposition of carbon-containing particles in the combustion exhaust gas on the filter up to an operating time of about 7 hours. At this point, the diesel particulate filter was regenerated by burning off the soot particles collected in the filter, which reduces the pressure to approximately 50 mbar. Then, in accordance with the loading of the filter caused by the soot emission of the diesel engine, an exhaust gas back pressure was built up, which after reaching values of approximately 200 to max. 350 mbar each followed by a spontaneous combustion after a cycle time of about 2 to 3 hours, so that overall an acceptable engine operating behavior resulted over the running time.

For comparison, FIG. 4 shows a long-term test of the diesel particle filter combustion behavior under comparable conditions as the diagram in FIG. 3, with the only difference that the combustion air was not additized by means of a carrier gas flow from the crankcase ventilation. The arrangement also contained the sublimator as shown in Figure 2, but the sublimator was not loaded with ferrocene pellets. The dotted curve plots the temperature at measuring point 2 in accordance with Flgur 2 in front of the diesel particulate filter. It can be seen that a slow but steady increase from about 190 to about 280 ° C was observed here. The solid line shows an almost linear increase in the exhaust gas back pressure upstream of the diesel particle filter measured at measuring point 2 according to FIG. 2. After a test period of approximately 18 hours, the exhaust gas back pressure had reached a value of 800 mbar, a value which in no way enables acceptable engine operation . The attempt was canceled. Although the temperature at measuring point 2 in accordance with FIG. 2 had reached a value of approximately 280 ° C. at the abovementioned point in time when the test was terminated, the diesel particle filter had not burned off, whereas according to the results in FIG , measured at the same measuring point of about 220 ° C.

The proposed method achieves the object in an advantageous manner, since with a specialist selection reserved specification of the operating data of the sublimator, the form of use of the ferrocene substance as pellets, other molded parts such. B. compacts or in the form of a crystalline powder an effective additive in the combustion of liquid heating or fuels with ferrocene is guaranteed.

The introduction of the carrier gas stream additized with ferrocene into the combustion chamber significantly improves the combustion behavior in the engine, which is operated with commercially available fuels, in Otto or Wankel engines with and without a downstream catalytic converter for exhaust gas afterburning. In particular, the occurrence of knocking in the engine is strongly suppressed. By changing the ignition timing, the power output of the engine can be increased. When operating with the same power, the influence of the active ingredient reduces fuel consumption.

The suppression of knocking processes by the introduction of the ferrocene active ingredient according to the invention is far stronger than if the active ingredient is contained in the fuel in a dissolved form. For this purpose, reference is made to the information with associated comparative test information in FIG. 5.

The introduction of ferrocene into the engine process increases the cleanliness of the combustion chamber by reducing existing residues and prevents the build-up of new deposits on pistons, piston rings, in the cylinder and on the cylinder head. In gasoline engines without a downstream catalytic converter for exhaust gas afterburning or pollutant reduction, which are still equipped with exhaust valves that are subject to wear, the ferrocene addition acts as a wear-reducing component on the exhaust valve seats.

In the case of diesel engines, the introduction of ferrocene as an additive to fuel combustion in the combustion chamber reduces the particle emissions and the proportion of polycyclic aromatic hydrocarbons that are attached to the carbon-containing particles.

The ferrocene addition according to the invention improves the regeneration ability of a diesel particle filter connected downstream of a diesel engine without additional devices for increasing the temperature or for initiating processes for periodic combustion of the carbon-containing particles (diesel soot) accumulating on the filter in order to maintain lower acceptable values for the pressure drop downstream of the filter or only made possible.

Claims (11)

1. Method for the doping of combustion fuels or motor fuels with ferrocene for the purpose of combustion with atmospheric oxygen or oxygen-containing gases, characterized in that

   a) vaporous ferrocene obtained from ferrocene crystals, or compacts or pellets produced therefrom, in a sublimator by sublimation at values of pressure and temperature in the vicinity of the coexistence line between solid and gaseous phase is transferred to a carrier-gas stream, preheated to 20 to 175°C, of the combustion gas or a substream of the latter and

   b) is combusted in a combustion chamber with the combustion fuel or motor fuel which is present in fine dispersion as solid or liquid particles or in vaporized form,

   c) the sublimed amount of ferrocene being 0.1 to 1000 mg per kg of combustion fuel or motor fuel.
2. Method according to Claim 1, characterized in that the sublimator is operated at a temperature from minus 40°C to plus 150°C, and a pressure of 100 mbar to 3 bar and with a vaporized amount of ferrocene of 1 to 100 mg per kg of combustion fuel or motor fuel.
3. Method according to Claim 1, characterized in that the carrier-gas stream is preheated to a temperature of 50 to 150°C.
4. Method according to Claim 1, characterized in that the ferrocene-vapour-containing carrier-gas stream is fed into the combustion chamber of a diesel engine.
5. Method according to Claim 1, characterized in that the ferrocene-vapour-containing carrier-gas stream is fed into the combustion chamber of a diesel engine equipped with a diesel particle filter.
6. Method according to Claim 1, characterized in that the ferrocene-vapour-containing carrier-gas stream is fed into the combustion chamber of a Wankel engine or auto engine.
7. Method according to Claim 1, characterized in that the ferrocene-vapour-containing carrier-gas stream is fed into the combustion chamber of a Wankel engine or auto engine having downstream controlled three-way catalyst for the afterburning of exhaust gas.
8. Method according to Claim 1, characterized in that the carrier-gas stream is injected by the crankcase vent line and fed via the sublimator which is charged with ferrocene and built into a motor-vehicle engine.
9. Method according to Claim 1, characterized in that the carrier-gas stream is completely or partly injected from the air intake line and is fed via the sublimator, which is charged with ferrocene and built into a motor-vehicle engine.
10. Method according to Claim 1, characterized in that the ferrocene compacts are produced from solvent-moist ferrocene crystals which originate from a crystallization solution and have a purity of at least 98.5% by weight, without addition of binder or the like.
11. Method according to Claim 1, characterized in that the ferrocene compacts are produced from ethanol-moist ferrocene crystals.

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