DE102010054362A1 - Synthetic fuel composition, useful for the internal combustion in diesel engines and heating systems, preferably for operating diesel motors for vehicles, comprises specified range of hydrocarbon, where hydrocarbons are partially alkanes - Google Patents

Abstract

Synthetic fuel composition comprises at least 12C-hydrocarbon, where the hydrocarbons are partially n-alkanes, and the proportion of respective n-alkane for each 12-22C number is less than 40 mol.%.

Description

The present invention relates to a synthetic fuel composition for combustion in diesel engines and heating plants, the composition containing hydrocarbons having at least 12 carbon atoms and the hydrocarbons being partially n-alkanes. In addition, the invention also relates to the use of the synthetic fuel.

Emission limits are being increasingly limited by lawmakers worldwide. As a consequence, a significant reduction in pollutants was achieved in the past years, above all in the case of exhaust gases from the motor vehicle sector. This positive development has been achieved mainly through improvements in engine combustion, sensor technology and engine control, as well as advances in the field of exhaust gas catalysis.

However, in future, in particular for emissions emanating from diesel vehicles, a progressive tightening of the limit values, in particular for nitrogen oxides (NO _x ) and particulates (PM), is to be expected. By variation of the Verbrennungsstöchiometrie these pollutants are only mutually influence, that is, a reduction of the one pollutant is bought by an increase in emissions of the other pollutant. Catalytic aftertreatment is very complicated in the case of diesel engine drives, since nitrogen oxides and particles can only be removed from the exhaust gas flow due to the fuel-oxygen ratio through multicomponent systems.

A third option for pollutant reduction opens up the use of improved fuels.

In order to avoid nitrogen oxides, it is particularly important to keep the gas temperature in the combustion chamber below 1000 ° C, whereby reactions of the nitrogen contained in the air can be effectively prevented. In order to reduce the particulate matter contained in the exhaust stream, complete combustion must be carried out avoiding the formation of acetylene and its derivatives. The higher the ignitability of the fuel, the better the temperature of the combustion process can be controlled and guided homogeneously, whereby the formation of nitrogen oxides and particles is reduced. In this context, it was previously known that a high cetane number is considered favorable. The cetane number describes the ratio of L-hexadecane to 1-methylnaphthalene as a measure of the ignitability of the diesel fuel.

From the US 5,389,111 It is known that the ratio of cetane number to the proportion of aromatics contained in the fuel significantly affects the combustion properties and can lead to significantly reduced particulate emissions at a favorable setting.

Also the US Pat. No. 7,208,078 B2 associates the cetane number with the aromatic portion and teaches a method of calculating the optimum ratio between the cetane number and the proportion of aromatics and nitrogen compounds in fuel mixtures to reduce particulate emissions.

The US 6,004,361 describes a fuel that not only has a defined cetane number, but also added to additional additives, whereby the cetane number is further increased and, as a consequence, the friction in the engine should be reduced. As a result, both particulate emissions and the components of the exhaust gas to be oxidized can be significantly reduced.

The reduction of NO _x emissions is carried out according to the US Pat. No. 7,063,729 B2 by adding a detergent additive, a further additive for improving the lubricity and a fully soluble platinum / cerium based bimetallic fuel borne catalyst.

In the field of diesel fuels, which are produced from renewable raw materials (biodiesel), the addition of additives is also known. This is how the WO 02/10317 A1 the addition of fatty acid esters, aviation fuel and a catalyst component with dissolved in the fuel platinum and / or cerium or iron to reduce the soot loading of the exhaust stream. The reduction of the NO _x emissions of a diesel from renewable raw materials can according to the WO 2007/089645 be achieved by admixing a Zündbeschleunigers and at least one plant extract.

As an alternative to enrichment of the fuel with organic additives or catalyst components is in the WO 02/26918 A1 described the addition of water, whereby an emulsion with 1 to 30 wt .-% water content is formed, which in turn results in the combustion of the fuel to a significant decrease in nitrogen oxides in the exhaust gas.

Against this background, as well as from new combustion systems for diesel engines under development, synthetic diesel fuels are also becoming increasingly important. An alternative to the large-scale established production of synthetic, so-called GTL diesel fuels via the Fischer-Tropsch (FT) synthesis provides in the WO 2006/076942 A1 described so-called MtSynfuels method ("methanol to synthetic fuels"), which are obtained from methanol starting from synthetic diesel and synthetic gasoline.

Also from the US 2004/0194367 A1 it is known to prepare an emulsion by adding water. The underlying fuel was not obtained by a distillation of petroleum, but is a product of the Fischer-Tropsch synthesis. In this Fischer-Tropsch synthesis, synthesis gas consisting of carbon monoxide and hydrogen is converted to liquid hydrocarbons at 160-200 ° C via a heterogeneous catalyst. Synthetic fuel production allows better control of carbon number distribution in the resulting product spectrum.

Also the US 2008/0052984 A1 starts from a Fischer-Tropsch diesel and proposes to reduce the sulfur content below 1 ppm and the aromatic content to less than 1 wt .-% and adjust the cetane number to a value above 60 in order to minimize the nitrogen oxide emissions ,

However, it is common to all these fuels that they can only be used either for the reduction of nitrogen oxides or for the reduction of particle emissions.

The object of the invention is therefore to improve the properties of the produced synthetic diesel fuel with respect to the emissions produced during combustion so that there is a simultaneous emission reduction in terms of nitrogen oxide emissions and particulate matter pollution.

This object is achieved by the features of claim 1 essentially in that the synthetic fuel composition for combustion in diesel engines and heating systems contains hydrocarbons having at least 12 and preferably at most 24 carbon atoms, these hydrocarbons are partially n-alkanes and the proportion of the respective n- Alkane for each carbon number of 12 to 20 below 40 mol%. According to comparative tests, the nitrogen oxide emissions are reduced by about 11 wt .-% and the particle emission even by about 35 wt .-% compared to conventional diesel.

Thus, while it can be generally assumed that the diesel fuel can be ignited more easily, the more unbranched hydrocarbon molecules are contained in percent, and thus a reduction of emissions could be achieved with the fuel of the invention surprisingly despite a reduction of the n-alkane Share emissions of nitrogen oxides and particles are reduced. This is particularly surprising in view of the fact that a high cetane number is commonly sought.

In addition, since a higher proportion of branched molecules is included in the composition, the packing density decreases. Consequently, the fuel composition according to the invention has a slightly reduced density compared to conventional diesel. However, since the fuel composition behaves neutrally with respect to its volumetric consumption compared to conventional diesel, a reduction in carbon dioxide emissions of about 4% can be achieved.

According to a preferred embodiment of the invention, the proportion of the respective n-alkane for each carbon number from 12 to 15 is even below 20 mol% and the proportion of the respective n-alkane for each carbon number from 16 to 20 is still below 35 mol%. %.

The proportion of the n-alkane for a carbon number of 12 is preferably between 15 and 19 mol%, particularly preferably between 16 and 18 mol% and very particularly preferably at 17 mol%, for a carbon number of 13 between 3 and 7 mol -%, more preferably between 4 and 6 mol% and most preferably at 5 mol%, for a carbon number of 14 between 5 and 9 mol%, preferably between 6 and 8 mol% and most preferably at 7 mol % and / or for a carbon number of 15 between 3 and 7 mol%, more preferably between 4 and 6 mol% and most preferably at 5 mol%, for a carbon number of 16 between 28 and 32 mol%, more preferably between 29 and 31 mole% and more preferably at 30 mole%, for a carbon number of 17 between 27 and 31 mole%, preferably between 28 and 30 mole% and most preferably at 29 mole%, for a carbon number of 18 between 5 and 9 mol%, more preferably between 6 and 8 mol% and very preferably At 7 mol%, for a carbon number of 19 between 16 and 20 mol%, particularly preferably between 17 and 19 mol% and completely particularly preferably at 18 mol% for a carbon number of 20 between 15 and 19 mol%, more preferably between 16 and 18 mol% and very particularly preferably at 17 mol%, for a carbon number of 21 between 35 and 39 mol% %, more preferably between 36 and 38 mole% and most preferably at 37 mole% and / or for a carbon number of 22 between 28 and 32 mole%, more preferably between 29 and 31 mole%, and most preferably at 30 mol%.

Such a fuel composition leads in particular to a simultaneous reduction of the emission of nitrogen oxides and particles if the proportion of compounds of a carbon number of 12 at 4.5 +/- 0.3 mol% of compounds with a carbon number of 13 at 4, 9 +/- 0.3 mol%, of compounds having a carbon number of 14 at 5.2 +/- 0.3 mol%, of compounds having a carbon number of 15 at 5.4 +/- 0.3 mol % of compounds having a carbon number of 16 at 5.4 +/- 0.3 mol% of compounds having a carbon number of 17 at 5.4 +/- 0.3 mol% of compounds having a carbon number of 18 at 4.8 +/- 0.3 mol%, of compounds with a carbon number of 19 at 4.3 +/- 0.3 mol%, of compounds with a carbon number of 20 at 3.5 + / 0.3 mol% of compounds having a carbon number of 21 at 2.8 +/- 0.3 mol%, of compounds having a carbon number of 22 at 2.1 +/- 0.3 mol% on the overall composition composition of the fuel is located. The total amount of n-alkanes is between 6.5 and 8.8 mol- ‰ for a carbon number of 12, and between 1.4 and 3.5 ‰ for a carbon number of 13, and between 2.5 and 4 for a carbon number of 14 , 7 mol- ‰, for a carbon number of 15 between 1.6 and 3.8 mol- ‰ for a carbon number of 16 at 1.5 to 1.75 mol-%, for a carbon number of 17 at 1.4 to 1 , 7 mol% for a carbon number of 18 between 2.4 to 4.4 mol- ‰, for a carbon number of 19 between 6.5 and 8.7 mol- ‰, for a carbon number of 20 between 5.2 to 6 , 7 mol- ‰, for a carbon number of 21 between 9.5 mol- ‰ and 1.1 mol-% and / or for a carbon number of 22 between 5 and 6.8 mol- ‰.

Moreover, the emissions of nitrogen oxides and particulate matter are particularly reduced when the fuel composition boils at lower temperatures in relation to classic Fischer-Tropsch, and therefore, according to a preferred embodiment of the invention, 5 vol.% Of the fuel composition at 212 +/- 5 ° C, 10 vol% of the composition at 221 +/- 5 ° C, 20 vol% of the composition at 225 +/- 5 ° C and 30 vol% of the composition at 230 +/- 7 ° C boil.

The invention further relates to the use of the synthetic fuel composition having the properties described in any one of claims 1 to 8 for operating diesel engines and heating systems. The use as a fuel for diesel engines extends to both the road, especially passenger cars and trucks, as well as engines, such as those used in agriculture, construction and on ships use.

Moreover, due to the slightly lowered cetane number, the synthetic fuel composition can also be used in new engine combustion processes in which diesel and gasoline engine technology are combined. The engines, often referred to as "combined combustion engines" or "Diesotto engines," are hermaphrodites that run in extreme lean conditions and self-ignite in some load ranges, while in others rely on the sparking spark. It is hoped that improvements in efficiency over conventional gasoline engines by up to 20% with low nitrogen oxide emissions.

Further developments, advantages and applications of the invention will become apparent from the following description of exemplary embodiments, measurements and the drawing. All described and / or illustrated features alone or in any combination form the subject matter of the invention, regardless of their combination in the claims or their dependency.

Show it

1 the scheme of a suitable for carrying out the process according to the invention plant;

2 the gas chromatogram of a fuel according to the invention;

3 the gas chromatogram of a resulting in the production of the fuel according to the invention middle distillate;

4 the gas chromatogram of a resulting in the production of the fuel according to the invention bottom product;

5 the reference gas chromatogram of an n-alkane mixture;

6 the gas chromatogram conventional Fischer-Tropsch diesel;

7 the amount of n-alkanes based on all compounds of the respective C number as a function of the C number.

1 schematically shows the process flow in the production of a fuel according to the invention. Initially, short-chain olefins are predominantly produced in the C number range C ₂ to C ₆ using a multistage synthesis starting from methanol as the starting material. These are oligomerized in a subsequent synthesis stage to longer-chain olefins with C numbers up to the C ₃₀ range. In the downstream of the oligomerization, separation by distillation, the hydrocarbon product is divided by the Siedelage into partial streams. The product obtained in the distillation bottoms and boiling in the diesel range is fed to a downstream hydrogenation, as the product of which ready-to-use diesel fuel is obtained.

This is done via line 1 In a heat exchanger, not shown, methanol is heated to a temperature of about 200 to 350 ° C and evaporated. The in the isothermal and operated with a salt bath reactor 2 incoming methanol vapor is at a suitable dehydrogenation catalyst (Sud-Chemie Synmax ^® 100, 4.5 × 4.5 mm tablets) at temperatures of 280 to 320 ° C, preferably 300 ° C and a pressure of 1.3 to 1.5 bara converted to dimethyl ether (DME) and water. The resulting DME / H ₂ O / MeOH mixture is then passed through line 11 an adiabatically operated olefin reactor 20 fed. At an inlet temperature of 365-390 ° C (start and end of the cycle) and a resulting outlet temperature of about 480 ° C, the mixture of a catalyst (Süd-Chemie, MTPROP ^® , 1.5 mm extrudate) at a Pressure of 1.25 to 1.35 bara reacted. Methanol is passed through the reactor at a space velocity (WHSV, the mass flow based on the catalyst mass) of 1 / h (900 g / h) and water of 3 / h (2700 g / h). The result is a product range of olefins, petroleum hydrocarbons and water vapor and, to a lesser extent, aromatics. Via wire 21 this mixture is then in the distillation column 22 in which it is separated into an aqueous phase, a gaseous hydrocarbon stream and a liquid hydrocarbon stream. The separation takes place in an atmospheric column at about 1.1 bara. At least parts of the aqueous phase can become the olefin reactor 20 to be led back. The liquid hydrocarbons are via line 24 another separation device 40 supplied in which they are further separated in a C ₆ hydrocarbon stream and a C ₇₊ hydrocarbon stream and aromatics-containing mixture at about 1.4 bara. The mixture of C ₇₊ hydrocarbons and aromatics can be removed as a gasoline product stream. The C ₆ hydrocarbon stream is via line 42 an oligomerization reactor 30 fed. These also include the gaseous hydrocarbons from the olefin reactor 22 via wire 25 fed. The oligomerization is carried out at temperatures between 200 and 450 ° C (for example, an inlet temperature between 220 and 280 ° C and an outlet temperature between 260 and 315 ° C or an inlet temperature between 250 and 275 ° C and an outlet temperature 265-290 ° C) and a pressure of 40 to 100 bar, preferably a pressure of 51 to 83 bara and in particular about 59 bara, in the presence of a zeolite catalyst of the pentasil type (Süd-Chemie, COD-9 ^® , 1.5 mm extrudate). The resulting olefins are then over line 31 a third separator 32 fed. A paraffin-rich hydrocarbon stream obtained in this separator is passed over line 34 to the olefin reactor 20 recycled, while an olefin-rich stream via line 33 back into the oligomerization reactor 30 is fed. The feed is at a space velocity of about 0.4 / h and the recycling stream at a space velocity of 1.3 / h, resulting in a ratio between recycling stream and feed flow of 3.1 to 3.4. Recycled are 92-95 wt .-% of the average and Kopfprodukt- and the Aromatenkopfproduktmenge. In addition, in the separator 32 other streams such as LPG or gas are deducted. As another product may be in the separator 32 a stream are separated, which forms the main product diesel after hydrogenation. The hydrogenation is carried out in a conventional manner in an in 1 Not shown hydrogenation reactor on a commercial hydrogenation catalyst. The reactor is operated adiabatically with an inlet temperature of 120 to 165 ° C, a resulting outlet temperature of 150 to 190 ° C and a pressure of about 28 bara.

example 1

The following Table 1 shows the result of a boiling analysis of the diesel fuel according to the invention DIN EN ISO 3405 , In a simple direct current distillation, 100 ml of the test substance are evaporated in a defined apparatus under controlled heating. The current boiling temperature is at Head of the apparatus measured, the vapors cooled by a cooler and the collected condensate volume determined by means of a measuring cylinder.

It clearly shows that the fuel composition according to the invention deviates in its boiling behavior from conventional diesel. In particular, the first boiling 30 vol .-% of the fuel composition have significantly higher boiling points than the corresponding fractions of a conventional diesel. As a result, the temperature range in which the fuel boils, can be reduced by more than 25 ° C, which favors a homogeneous combustion.

Example 2

The composition of the fuel mixture according to the invention was also determined by means of gas chromatography. For this purpose, three different liquid samples, which are referred to below as diesel, sump and middle distillate, were analyzed. Each sample (~110 mg) was dissolved with 10 ml of cyclohexane in an ultrasonic bath at 60-70 ° C. Approximately 1 μl of this solution was added to the GC injector. The experimental conditions can be found in detail in Table 2. Table 2

The gas chromatograms of the various samples and an n-alkane mixture of C ₈ -C ₄₀ and a FT diesel are in the 2 to 6 shown. The n-alkane mixture serves as a reference chromatogram.

The analyzes show that isoalkanes are the main components of the three samples. In the diesel sample hydrocarbons (HC) could be found between C ₁₂ -C ₂₄ , in the bottom sample between C ₁₂ -C ₂₀ and in the middle distillate sample between C ₇ -C ₁₂ .

7 shows the n-alkane portion of each C number for the three samples and for FT diesel, with the proportion of unbranched hydrocarbons in the fuel of the invention is significantly lower than in the conventional Fischer-Tropsch diesel.

Example 3

The following tables show emissions tests carried out on a Golf V 1.9 TDI under the New European Driving Cycle (NEDC). Thereafter, the vehicle is subjected on a dynamometer a standardized according to the respective test procedure driving behavior, which should describe as possible the typical driving behavior of a motor vehicle driver. In comparison, there are clear differences in the NO _x and particle emissions between a synthetic fuel according to the invention and the values of a conventional diesel fuel. In comparison with conventional petroleum-based diesel fuel, a simultaneous and significant emission reduction of nitrogen oxides (NO _x , -11 wt%) and particulate matter (PM, -35 wt%) occurs without any intervention in the engine or engine control , Even when using synthetic diesel fuels from other sources (so-called GTL diesel via Fischer-Tropsch synthesis), a simultaneous reduction of these air pollutants is not observed.

LIST OF REFERENCE NUMBERS

1

management

2

DME reactor

3

management

20

olefin reactor

21

management

22

separating device

23

management

24

management

25

management

30

oligomerization

31

management

32

separating device

33

management

34

management

40

separating device

41

management

42

management

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 5389111 [0006]
• US 7208078 B2 [0007]
• US6004361 [0008]
• US 7063729 B2 [0009]
• WO 02/10317 A1 [0010]
• WO 2007/089645 [0010]
• WO 02/26918 A1 [0011]
• WO 2006/076942 A1 [0012]
• US 2004/0194367 A1 [0013]
• US 2008/0052984 A1 [0014]

Cited non-patent literature

• DIN EN ISO 3405 [0037]

Claims (10)

Synthetic fuel composition for combustion in diesel engines and heating installations , the composition containing hydrocarbons having at least 12 carbon atoms and the hydrocarbons being partially n-alkanes, characterized in that the proportion of the respective n-alkane for each carbon number from 12 to 20 below 40 molar % lies. A fuel composition according to claim 1, characterized in that the proportion of the respective n-alkane for each carbon number of twelve to fifteen is below 20 mol%. A fuel composition according to claim 1 or 2, characterized in that the proportion of the respective n-alkane for each carbon number of sixteen to twenty is below 35 mol%. Fuel composition according to one of the preceding claims, characterized in that the proportion of the respective n-alkane for a carbon number of twelve between 15 and 19 mol%, for a carbon number of thirteen between 3 and 7 mol%, for a carbon number of fourteen, between 5 and 9 mol% and / or for a carbon number of fifteen is between 3 and 7 mol%. Fuel composition according to one of the preceding claims, characterized in that the proportion of the respective n-alkane for a carbon number of sixteen between 28 and 32 mol%, for a carbon number of seventeen, between 27 and 31 mol%, for a carbon number of eighteen, between 5 and 9 mol%, for a carbon number of nineteen between 16 and 20 mol% and / or for a carbon number of twenty is between 15 and 19 mol%. Fuel composition according to one of the preceding claims, characterized in that the proportion of the respective n-alkane for a carbon number of twenty-one between 35 and 39 mol% and / or for a carbon number of twenty-two between 28 and 32 mol%. Fuel composition according to one of the preceding claims, characterized in that the proportion of compounds having a carbon number of twelve at 4.5 +/- 0.3 mol%, of compounds having a carbon number of thirteen at 4.9 +/- 0.3 mol%, of compounds with a carbon number of fourteen at 5.2 +/- 0.3 mol%, of compounds with a carbon number of fifteen at 5.4 +/- 0.3 mol%, of compounds having a carbon number of sixteen at 5.4 +/- 0.3 mol%, of compounds with a carbon number of seventeen at 5.4 +/- 0.3 mol%, of compounds with a carbon number of eighteen at 4.8 +/- 0.3 mol%, of compounds with a carbon number of nineteen at 4.3 +/- 0.3 mol%, of compounds having a carbon number of twenty at 3.5 +/- 0.3 mol%, of compounds having a carbon number of twenty-one at 2.8 +/- 0.3 mol% and / or of compounds having a carbon number of twenty-two is 2.1 +/- 0.3 mol%. Fuel composition according to one of the preceding claims, characterized in that 5% by volume of the composition at 212 +/- 5 ° C, 10% by volume of the composition at 221 +/- 5 ° C, 20 vol .-% of the composition at 225 +/- 5 ° C and Boiling 30 vol .-% of the composition at 230 +/- 7 ° C. Use of a synthetic fuel composition according to any one of claims 1 to 8 for operating diesel engines, in particular vehicles, and heating systems. Use of a synthetic fuel composition according to any one of claims 1 to 8 for operating engines in which diesel and gasoline engine technology are combined.

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