JP2003514064A - Reduced particulate matter distillate fuel - Google Patents

Abstract

  (57) [Summary] The distillate fuel is selectively oxidized in the presence of a titanium silicalite catalyst, preferably with hydrogen peroxide, to produce hydroxyl and / or carbonyl groups bonded to paraffinic carbon atoms of the diesel fuel molecule to form a fuel in the fuel. At least 0.1% by weight, preferably at least 0.3% by weight of oxygen is provided. The fuel, which produces low particulate emissions on combustion, preferably has a low sulfur content, a polycyclic aromatics content and an olefin content and a high cetane number.

Description

Detailed Description of the Invention

TECHNICAL FIELD This invention relates to fuels that are atomized for combustion, such as diesel fuels, which have improved environmental performance after distillate, and in particular combustion. While diesel fuels have many advantages, they suffer from the disadvantage that they produce undesirable pollutant emissions when burned. These are particularly problematic in diesel engines, where emissions are emitted to the atmosphere in the exhaust gas of diesel-powered vehicles. Not that bad,
Similar problems arise from the burning of heating oil. The present invention is also applicable to stationary motors and ship motors that operate by fuel injection of heavy distillate fuel.

BACKGROUND OF THE INVENTION Middle distillates and heavy marine fuels are typically obtained by distillation, cracking and fractional distillation of crude oil. They are a complex mixture and the pollutants produced by their combustion take several forms. The presence of sulfur in the fuel results in sulfur-containing pollutants, especially sulfur oxides and sulfates. The presence of nitrogen in the fuel and in the air in which the fuel is burned results in the production of oxides of nitrogen (otherwise known as NOX). The presence of polynuclear aromatic compounds in the fuel can result in PNA emissions. In addition, combustion processes involving the ignition of atomized fuel particles as opposed to vaporized fuel (such as in gasoline-powered engines) can result in incomplete combustion of fuel in the engine or burner, which results in particulate matter in the exhaust gas. This can result in the formation of objects or soot particles.

These are not new problems, and over the years refiners have developed their refining techniques to produce middle distillate fuels and heavy fuels that result in reduced emissions. Engine and burner manufacturers have developed improved equipment to reduce emissions, and additive suppliers have added additives to enhance combustion and enable the use of more environmentally friendly fuels. Has been developed. However, there is a constant desire to be reflected in regulations to provide fuel compositions that produce even lower levels of pollutants upon combustion. This is the European defined specification for diesel fuel [the maximum level of sulfur allowed in 1995 is 500 ppm, in 2000 it is 350 and in 2005 it is expected to be 50 ppm] And European Union directives on the emission of gas and particulate pollutants from diesel engines. These specifications and trends are Oi
l & Gas Journal (OGJ Special on “Future Transport Fuels”) Nigel R. entitled “EU and Petroleum Industry Improving EU Fuel Quality, Efficiency” 12 July 1999.
The paper by Cuthbert is shown in Table 2 on pages 40-45, especially page 44. “Official Jou
rnal of the European Communities ”L350 / 58-L350-68“ Corrects Council Directive 93/12 / EEC for Petroleum Fuels and Diesel Fuels Eur 13 Oct 1998
Opean Parliament and Council Directive 98/70 / EC ”and addendum II (L3
50/66) contains the specification for diesel for the year 2000 (maximum sulfur content of 350 mg / kg) and Addendum IV L p. 350/68 contains its specification for the year 2005. Similarly,
The amount of polycyclic aromatic compounds allowed is reduced as well as the proportion of high-boiling substances,
At the same time, the cetane number, which is a measure of the burning capacity of the fuel, is increasing.

Therefore, there is a need for a technology that provides a distillate fuel that burns cleanly and that meets the stringent and stringent environmental requirements. FIELD OF THE INVENTION The present invention relates to distillate fuels and their manufacture, in particular those boiling in the middle distillate zone with improved combustion, especially those producing low particulate emissions upon combustion. It has long been recognized that soot particles are formed in diesel fuel due to incomplete combustion often resulting from incomplete mixing of fuel and combustion air prior to actual combustion. Various attempts have been made to enhance combustion, for example it has been proposed in WO 97/42405 to inject a liquid containing peroxide, preferably into the combustion chamber after the start of the combustion phase. U.S. Pat. No. 4,723,963 oxidizes benzylic carbon atoms in aromatic compounds in fuels by free radical oxidation to increase the cetane number of the fuel. It is worth noting that the level of aromatics required for the fuel of US Pat. No. 4,723,963 is higher than that of modern fuels. Moreover, US Pat. No. 4,723,963 clearly states that the paraffinic hydrocarbon moieties should not be oxidized.
This is because it is these hydrocarbyl groups that provide the desired high cetane number. As early as the 1940s, US Pat. Nos. 2,317,968 and 2,365,220 suggested the oxidation of diesel fuel by free radical oxidation.

It is also known to incorporate additives that improve the cetane number of the fuel. U.S. Pat.Nos. 5,114,433 and 5,114,434 are direct distillation fuels and visco-reduced
) To improve the respective cetane number of diesel fuel. These patents aim to solve the drawbacks with cetane improving additives, the choice of additives being naturally relatively insoluble in water, chemically stable thereto and sufficiently soluble in diesel fuel. Yes, stable, non-corrosive and non-toxic. In these patents the cetane number of the fuel is determined by contacting the diesel fuel with hydrogen peroxide in the presence of formic acid, acetic acid or propionic acid or optionally with formic acid, peracetic acid or perpropionic acid in the presence of hydrogen peroxide. Will be increased. These patents do not show the nature of the products produced by contacting the fuel with free radical peroxide-based materials, and attempts to repeat these processes have resulted in oxidation of the fuel. Did not bring. However, if the reaction occurs, peroxide,
It is believed that a complex mixture containing ester groups and acid groups will be produced.
These groups have a detrimental effect on the short-term and long-term stability of the fuel, and acid functional groups can make the fuel corrosive. US Pat. No. 5,324,335 discloses synthetic diesel fuel produced by the Fischer-Tropsch synthesis. It produces fuels containing primary alcohols that give an oxygen content of 3% by weight, and it is speculated that the presence of alcohol contributes to the superior performance for particulate airborne emissions.

DISCLOSURE OF THE INVENTION The present invention relates to the reduction of particulate matter formed from the combustion of fuels and is applicable to fuels containing a wide range of sulfur levels, typically above 500 ppm and below 30 ppm. In particular, the inventors have found that distillate fuels, especially middle distillate oils containing less than 350 ppm of sulfur, are oxidized to produce hydroxyl groups and / or hydroxyl groups chemically bonded to paraffinic molecules in the fuel.
Or providing carbonyl groups, and that the amount of particulate matter generated after combustion of oxidized fuel is significantly reduced when compared to the amount of particulate matter generated after combustion of unoxidized fuel. It was The present invention relates to high sulfur fuel and ultra low sulfur fuel (less than 50 ppm,
Can be used to reduce particulates from both (especially less than 30 ppm). The inventors have also found that the technique of the present invention can be used to reduce the sulfur and nitrogen levels of fuels, especially those of fuels that already have relatively low sulfur levels. Therefore, in one aspect, the present invention provides a hydroxyl group chemically bonded to a paraffinic carbon atom in a distillate fuel molecule in an amount that provides at least 0.1 wt% oxygen in the fuel, preferably at least 0.3 wt%, and / or A distillate fuel containing a carbonyl group is provided.

BEST MODE FOR CARRYING OUT THE INVENTION The distillate fuel is an intermediate distillate fuel, for example, petroleum boiling in the range of 150 to 550 ° C., preferably 150 to 450 ° C., more preferably 150 to 400 ° C. It is preferably distillate oil and may be obtained by atmospheric distillation or vacuum distillation of crude oil which may have been cracked. The fuel of the present invention is particularly useful as a diesel fuel. It is particularly preferred that the distillate has a 95% by volume distillation point (as measured according to EN-ISO 3405 (1988)) of 370 ° C or lower, preferably 360 ° C or lower. Fuel has a density of 845 kg / m ³ or less and 350 p
It is preferred to have a sulfur content below pm, preferably below 50 ppm, which is generally obtained by hydrodesulfurization. Although the present invention has applicability to a range of fuels, it is particularly useful in the production of fuels that meet emerging and more stringent environmental specifications. It is further preferred that the fuel from which the fuel of the present invention is derived comprises up to 11% by weight of polycyclic aromatic compounds, up to 15% by weight of olefins and has a cetane number of at least 50, preferably at least 52. .
However, the present invention also relates to heavy distillate fuels used in stationary and marine motors, such as the fuels sometimes known as bunker fuels and the heavy poor quality fuels occasionally used in diesel vehicles. If the fuel has a high olefin content, care must be taken to avoid the cleavage of molecules in the fuel during the oxidation reaction, which can form undesired acid functional groups. Therefore, the olefin content of the fuel to be oxidized is preferably 10% or less, more preferably 5% or less. 1.
Most preferred is a bromine number of less than 5, preferably 0.5 or less.

The oxidized fuel is 0.3 to 15% by weight, more preferably 0.5 to 15% by weight, especially 1 to 10% by weight.
It is preferred to contain wt% oxygen. An oxygen content of 1 to 4% by weight is preferred, 2 to
Most preferred is 3% by weight. The term paraffinic carbon atom means a saturated carbon atom, which is bonded to at least one hydrogen atom and not directly to the aromatic nucleus. The paraffinic carbon atom may be of the formula CR _n H _m , where R is an alkyl or alkylidene group, m + n is 4 and m is 1 or 2. Distillate fuel molecules are molecules that are separated in a refinery during the distillation process used to make fuels, hydroxyl or carbonyl groups being provided by the oxidation of these molecules, and hydroxyl groups are generally secondary or tertiary. It is a hydroxyl group. The hydroxyl and / or carbonyl groups in the fuel are conveniently provided by the selective oxidation of the fuel. A suitable method for fuel oxidation is EP 0376453B, PCT application W
O 93/04775, WO 90/05126 and WO 93/15035, U.S. Patent Nos. 5,021,607 and 5,7
39,076 and British Patent Application No. 9406434.2.

These patent specifications describe various titanium-containing silicon-based zeolites,
These have been found to be particularly useful catalysts for the oxidation of saturated paraffinic carbon atoms with peroxides, such as hydrogen peroxide, to yield hydroxyl or carbonyl groups. The methods of these patents result in selective oxidation to hydroxyl and carbonyl groups, unlike prior art free radical methods. The use of these methods allows fuels in which 70% or more, preferably 80% or more of the oxygen bound to paraffinic carbon atoms in the fuel is in the form of hydroxyl and / or carbonyl groups resulting in a significant improvement in fuel performance. To be able to be obtained. The hydroxyl groups produced by these methods are predominantly secondary and tertiary hydroxyl groups, and all hydroxyl groups may be secondary and / or tertiary. If carbonyl groups are formed, it may be desirable to selectively hydrogenate them to hydroxyl groups, eg by conventional hydrogenation techniques using heterogeneous catalysts.

Therefore, the present invention selectively oxidizes the paraffinic carbon atoms in the distillate fuel molecules in the distillate fuel boiling in the range of 150 ° C. to 400 ° C. to selectively oxidize the hydroxyl groups bonded to the paraffinic carbon atoms. Further provided is a method of obtaining a fuel comprising groups and / or carbonyl groups and an oxygen content of at least 0.1% by weight, preferably at least 0.3% by weight. In a preferred embodiment of the method, the fuel is selectively oxidized with organic peroxide, ozone or hydrogen peroxide in the presence of a titanium zeolite catalyst having an infrared absorption band near 950 cm ^-1 or 960 cm ^-1 . Hydrogen peroxide is particularly preferred as the oxidant. The catalyst is preferably in the form of powder, pellets, tablets or granules and may be mixed with inert materials such as carriers or binders. The catalyst may also be mixed with other materials such as zeolites.

A preferred catalyst is J Chem Soc Chem Commun 1992, page 589 and “Preparation, Characterization and Catalytic Properties of Titanium-Containing Zeolites” AJHP Van de Pol-PhD Thesis (Eindhov
based on crystalline synthetic materials containing silicon, alumina and titanium oxides as described by En University (NL) 1993) and characterized by infrared absorption bands around 950 cm ^-1 or 960 cm ^-1 . The catalysts should have free or accessible titanium in their structure, typically of various ratios of the general formula SiO ₂ : TiO ₂ : Al ₂ O ₃ , but Al ₂ O ₃ is Not an essential ingredient. These catalysts are described in J Chem Soc Chem Commun 1992, page 589, US Pat. No. 5,021,607.
No. or patent application WO 97/33830, which may be prepared from a source of silicon oxide, a source of titanium oxide, optionally a source of aluminum oxide, a nitrogenated organic base, or Catalysis Letters 1 (1988). ) B. Kraushaar and JHC on pages 81-84.
It may be prepared by dealumination of ZSM-5 and reaction with titanium tetrachloride vapor as described by Van Hoof. The catalyst may contain small amounts of other metals such as aluminum, gallium and iron (as described in EP 0226258). The catalyst may also be a dual catalyst which allows the in situ production of hydrogen peroxide from oxygen and hydrogen using a noble metal such as palladium (WO 00/13
5894). The dual catalyst can be prepared by impregnating a titanium-containing zeolite with a noble metal.

US Pat. No. 4,824,976 relates to the use of these types of catalysts for the epoxidation of olefins with H ₂ O ₂ , where x is from about 0.0001 to about 0.04.
May be up to. British Patent 2083816 item and the second 2116974 relates to the use of similar catalysts for the introduction of hydroxy groups into aromatic substrates by oxidation with H ₂ O _2. These patents are incorporated herein by reference for their description of infrared and x-ray diffraction analysis of the catalyst. As noted, as the amount of titanium present increases, the band intensity at about 950 cm ^-1 increases. It is preferred to use the titanium beta form. What's more, it has a pore size that can easily accommodate distillate oil molecules that are to be oxidized (typically C ₁₄ -C ₁₇ hydrocarbons) and can result in greater conversion in the oxidation reaction. Because it has.

The catalyst is i) a) a silicon oxide source (SiO ₂ ) b) a titanium oxide source (TiO ₂ ) c) an aluminum oxide source if necessary d) an alkali metal source if necessary e) a nitrogen-containing organic base, and f) water Can be prepared by heating the reaction mixture containing ii) separating the produced catalyst from the reaction mixture, and iii) calcining the separated crystals to produce the catalyst. The catalyst used in the present invention is preferably prepared from a reaction mixture consisting of silicon oxide, titanium oxide, aluminum oxide and possibly a source of alkali oxides, a nitrogen-containing organic base and water. The composition with respect to the reagent molar ratio is as specified above.

The source of silicon oxide may be a tetraalkyl orthosilicate, preferably tetraethylorthosilicate, or simply a silicate in colloidal form. The titanium oxide source is preferably TiCl ₄ , TiOCl ₂ and Ti (alkoxy) ₄ , preferably Ti
It is a hydrolyzable titanium compound selected from (OC ₂ H ₅ ) ₄ . When used, the aluminum oxide source may be an aluminum salt or aluminum metal. The organic base is tetraalkylammonium hydroxide, especially tetramethylammonium hydroxide. In a preferred method of producing a catalyst, a mixture of these reactants is prepared in the autoclave at a temperature of 130-200 ° C. under its own generated pressure for 1-30 days, until crystals of the catalyst precursor are produced. It is preferably subjected to hydrothermal treatment for a period of 6 to 30 days. These are separated from the mother liquor, carefully washed with water and dried. In the anhydrous state, they have the following composition SiO ₂ : Al ₂ O ₃ : TiO ₂ : (RN +) ₂ O. The mixture is preferably heated in an autoclave at a temperature of 130-200 ° C, preferably about 175 ° C, for about 10 days to cause crystallization. The precursor crystals are then heated in air at 550 ° C. for 1-72 hours to eliminate the nitrogenated organic base. The final catalyst has the following composition: SiO ₂ : Al ₂ O ₃ : TiO ₂ . The preferred molar ratios (MR) of the different reactants with respect to the silicon oxide source (SiO ₂ ) are listed in the table below.

[0015]

[Table 1]

The catalyst may be aggregated in powder, pellet or tablet form to form crystalline clusters, which are also active and easily recovered after the oxidation reaction. The catalyst may also include a carrier and / or support. Preferred catalysts are the titanium silicalite catalyst known as TS-1 and the alumino titanium silicalite known as titanium-beta. The oxidant used to oxidize the distillate fuel may be hydrogen peroxide or organic peroxide. Hydrogen peroxide is preferred and may be added neat or may be prepared in situ as described above. It is also preferred that the diesel fuel be in liquid or dense phase at the conditions used for the oxidation reaction. Also, when hydrogen peroxide is used, it is used as an aqueous solution and the reaction is carried out in the presence of a solvent. If an organic peroxide is used, no solvent may be needed, or the peroxide itself may act as the solvent.

According to the present invention using selective catalytic oxidation, a saturated aliphatic or cyclic compound in a distillate fuel containing an aliphatic substituent of an alkylaromatic compound is oxidized to give a secondary and / or tertiary hydroxyl group. It is possible to generate groups and / or carbonyl groups. Short or long chain, branched or linear alkanes containing 3 to 22, typically 3 to 18 and more preferably 12 to 18 carbon atoms as the saturated group which can be oxidized by the method of the present invention, Cyclic alkanes and mono- and poly-alkyl aromatic compounds (at least one of the alkyl groups of which contains at least 3, more preferably 3-18, most preferably 12-18 carbon atoms) and mono- and poly- -Alkyl cyclic alkanes.

The inventors have surprisingly found that by selecting appropriate conditions, saturated groups in distillate fuels can be highly selectively oxidized to alcohols and carbonyls under relatively mild conditions. The reaction conditions, choice of catalyst, amount of catalyst used and ratio of oxidant to distillate fuel will depend on the distillate fuel composition and the desired oxygen level. The aliphatic substituent may be part of an all-aliphatic compound, an aryl compound (alkylaromatic) or an alkylnaphthene compound. In addition, the compounds are electron repulsive and may therefore contain other functional groups that are not reactive. Further, the catalytic oxidation may oxidize residual sulfur compounds in the fuel. This can convert sulfur species to species that can be more easily removed, thus the present invention can provide the additional advantage of allowing further reduction of sulfur levels. The inventors have found that the reactivity order for aliphatic compounds decreases from tertiary carbon atoms to secondary carbon atoms to even primary carbon atoms.

The oxidant used in the reaction is an organic peroxide added or prepared in situ,
It may be ozone or hydrogen peroxide, preferably an aqueous hydrogen peroxide solution. The aqueous solution contains 10 to 100% by weight, preferably 10 to 70% by weight hydrogen peroxide, for example diluted hydrogen peroxide (40% by weight in water). It is also preferred that a polar solvent be present, for example ketones or alcohols, acetone, methanol, ethanol or butanol. The solvent will increase the solubility of the distillate fuel in the H ₂ O ₂ aqueous phase when aqueous hydrogen peroxide is used. The particular advantages of the process of the invention are that it uses mild temperature and pressure conditions, high conversion and yield, and low by-product formation. Especially, the conversion rate of hydrogen peroxide is high. However, the conversion of hydrocarbons is relatively low, preferably 30% or less. Above a conversion of 30%, there is a risk that di-ketones will be formed, leading to the cleavage of oxidised molecules and possibly the formation of acid functional groups in the oxidised fuel. The presence of these acid functional groups can result in the fuel being corrosive.
Therefore, it is preferred to use a substoichiometric amount of hydrogen peroxide based on distillate fuel. Further, it is preferable that the oxidized fuel has a total acid value of 1 mgKOH / g, preferably 0.5 mgKOH / g or less, and more preferably 0.2 mgKOH / g or less. If the fuel is oxidised to TAN above these levels, it may be necessary to remove the acid, for example by an alkaline wash.

The optimum reaction temperature for oxidation is 50 to 150 ° C., preferably about 100 ° C. The pressure should be such that all substances are in the liquid or dense phase. The reaction can be carried out at room temperature, but higher reaction rates are obtained at elevated temperatures, eg under reflux conditions. Autogenous pressures created by reflux conditions or heated reactants may be used, allowing the use of pressurized reactors to reach even higher temperatures. 1
The use of high pressure in the range of ~ 100 bar (10 ⁵ -10 ⁷ Pa) can increase the conversion and selectivity of the reaction. The oxidation reaction is carried out under batch conditions or in a fixed bed, and the use of heterogeneous catalysts allows for continuous reactions in single-phase or two-phase systems. The catalyst is stable under the reaction conditions,
It can be recovered and reused. The method of the invention is preferably carried out using hydrogen peroxide in the presence of a solvent. The solvent is important. This is because it allows the distillate fuel and hydrogen peroxide to interact and contact the catalyst. Therefore, it should dissolve the distillate fuel and the aqueous phase, which is generally present due to the use of aqueous hydrogen peroxide as the oxidant, or allow the two phases to diffuse into each other. . Polar compounds are preferred, examples of preferred solvents are supercritical carbon dioxide, alcohols, ketones, ethers, glycols and acids having a number of carbon atoms which is not too high, preferably 8 or less. Methanol or tertiary butanol is the most preferred alcohol, acetone is the most preferred ketone, and acetic acid or propionic acid is the most preferred acid. Mixtures of these solvents may also be used. The amount of solvent is important and can affect reaction products and conversions, and the choice of solvent and its amount depends on the composition of the distillate fuel. The solvent improves the miscibility of the hydrocarbon phase and the aqueous phase, which is generally present due to the use of aqueous hydrogen peroxide as the oxidant.

The technique of the present invention provides the additional benefit that the oxidation reaction can convert sulfur species in the distillate fuel to more polar species that are more easily removed. For example, distillate fuels contain sulfur in the form of thiophenes, sulfides and mercaptans, which can be converted to sulfoxides and sulfones by the oxidation techniques used in the present invention. These more polar sulfoxides and sulfones can then be removed by distillation, washing with water or polar solvents or adsorption by, for example, silica gel. This raises their sulfur level to 200p
It is particularly useful for further reducing the sulfur level of fuels already hydrodesulfurized to reduce to below pm, especially below 100 ppm, and more particularly below 50 ppm. Although these techniques can work at high sulfur levels, the large amounts of hydrogen peroxide required can render these techniques unattractive. The techniques of the present invention are also beneficial in reducing nitrogen levels in fuels. This is because the oxidation reaction converts nitrogen-containing species into nitrogen oxides that can be easily removed by distillation, washing with water or polar solvents or adsorption by, for example, silica gel, and when used, removal of nitrogen species It is preferable that the operation is the same as the removal of the oxidized sulfur species.

The presence of hydroxyl and / or carbonyl groups in the fuel is determined by conventional NMR techniques, eg Sp. By DH Williams and I. Fleming, published by McGraw-Hill Printing Company.
It can be measured by the technique described in ectroscopic methods in Organic Chemistry. Gas chromatography, including infrared spectroscopy and gas chromatography mass spectroscopy may also be used. The presence of hydroxyl groups is indicated by a band in the infrared spectrum near 3500 and the carbonyl group is indicated by a band near 1710. These techniques can also be used to determine whether a hydroxyl group is primary, secondary or tertiary. Secondary and tertiary groups are preferred.

The distillate fuel of the present invention may be treated with additives to improve its performance. Although the oxidised fuel of the present invention shows a significant reduction in particulate formation upon combustion of the fuel,
The impact on hydrocarbon and carbon monoxide emissions is small, and in some cases may be accompanied by a slight increase. However, these can be eliminated by the use of typical exhaust oxidation catalysts in engine exhaust systems. Heating oils and other distillate petroleum fuels, such as diesel fuels, tend to precipitate as large crystals of wax in such a way that at low temperatures they form a gel structure, which causes them to lose their ability to flow into the fuel. including. The lowest temperature at which the fuel still flows is known as the pour point. Difficulties arise in transporting fuel through piping and pumps as the temperature of the fuel decreases and approaches the pour point. Furthermore,
Wax crystals tend to clog fuel lines, screens, and filters at temperatures above the pour point. These problems are well recognized in the art and various additives have been proposed, many of which are commercially available to lower the pour point of fuel oils. Similarly, other additives have been proposed and are commercially available to reduce the size and change the shape of the wax crystals that form. Crystals of even smaller size are desirable. After all, they are unlikely to clog the filter. Certain additives prevent the wax from crystallizing as platelets and give it a needle-like habit, with the resulting needles being more likely to pass through the filter than the platelets. Also, the additive may have the effect of keeping the crystals formed suspended in the fuel, and the resulting reduced settling helps prevent clogging.

Effective wax crystal modifiers (as measured by cold filter plugging point (CFPP) test and other workability tests, as well as simulated performance and field performance) are ethylene-vinyl acetate copolymers or ethylene-propionic acid. It may be obtained by the addition of rheology modifiers based on vinyl copolymers. U.S. Pat.No. 3,961,916 describes a middle distillate flow improver that includes a wax growth inhibitor and a nucleating agent, the former being a low molecular weight ethylene-vinyl ester copolymer having a high ester content. Preferably, the latter is a high molecular weight copolymer with a low ester content, and both esters are preferably vinyl acetate, but this is not necessary. DE-A-2407158 describes a middle distillate flow improver comprising a mixture of low molecular weight ethylene-vinyl ester copolymer and ethylene-acrylic ester copolymer, both copolymers containing at least 40 mol% of the ester component. Including.

FR-A-2061457 is a first copolymer of ethylene and an olefinically unsaturated monomer containing 3 to 30 carbon atoms (having an average molecular weight of 700 to 3000), and ethylene and 3
A mixture of copolymers comprising a second copolymer of olefinically unsaturated monomers containing -60 carbon atoms (above 3000 and having an average molecular weight of up to 60,000) is described. EP0648257 describes fuel oil additives effective in improving the low temperature fluidity of oils, compositions containing at least two different copolymers of ethylene and an unsaturated ester, or ethylene and at least two different types. It is based on the observation that a composition containing a copolymer of unsaturated ester derived units of is an effective cold flow improver with advantages over previously proposed compositions. Examples of other additives that may be included in the distillate fuel are cetane improvers, antifoam additives, dispersants such as alkylsuccinimides, pigments and antioxidants. Recently,
Lubricating additives such as esters have been incorporated into diesel fuels to offset the loss of lubricity caused by deep hydrofining used to reduce sulfur levels in the fuel. However, the incorporation of oxygen into the fuel according to the invention can improve the lubricity of the fuel. Lubricity is required to prevent pump wear in diesel engines.

The inventors believe that the introduction of hydroxyl and / or carbonyl groups does not result in adverse interactions with other additives present in diesel fuel. The oxidised fuels of the invention may be used by themselves as diesel fuels or as fuels for stationary or marine engines. They may also be blended with other distillate fuels and / or biofuels, for example fuels derived from rapeseed methyl ester or soybean ester. We believe that, unlike many other modified fuels, the fuels of the present invention perform well in normal engines, such as diesel engines, which operate under normal conditions without the need for special lubricants. . The introduction of hydroxyl and / or carbonyl groups in the fuel will not cause detrimental interactions with the lubricants or lubricant additives that it encounters at the fuel lubricant boundary. Furthermore, we believe that particulate formation during fuel combustion can be reduced by 5-50%, and sometimes more, depending on the composition of the diesel.

Emission tests may be performed on a commercial passenger car equipped with a direct injection diesel engine (eg VW Golf 1.9TDi). A passenger car with a warmed-up engine can be operated over a regulated European driving cycle for emission measurements. This is 4 "basic city cycle" (ECE-15) and 1 "outside city cycle" (E
UDC) and covers a range of speeds and loads. A particulate tunnel connected to the passenger vehicle exhaust may be used for particulate recovery.
Granules are pre-conditioned and weighed with filter paper (one for ECE,
One is for the EUDC phase of the operating cycle). The filter paper is then reweighed after the test to measure the weight of the recovered particulate material. Each test fuel is preferably tested three times over the ECE / EUDC cycle and the base fuel is preferably tested before and after three test fuel iterations.

On an industrial scale, the distillate fuels of the present invention may be readily produced by oxidation of a suitable refinery stream, eg, a boiling stream in the range 230-320 ° C. Alternatively, the sidestream may be oxidized and then blended with conventional distillate oil to produce a final fuel having the desired oxygen level. However, it may be difficult to produce a sidestream with sufficiently high oxygen levels to produce the desired final levels during blending without causing cleavage and acid formation. The oxidation unit in the refinery is preferably located downstream of the hydrofining unit currently used in most refineries to reduce sulfur levels in the fuel. This will increase the conversion to hydroxyl groups. This is because the amount of sulfur species, olefins and benzyl carbon atoms, which would otherwise react with the oxidant, were reduced during the hydrofining operation. Additional unit units may be provided downstream of the oxidation unit unit for removal of oxidized sulfur and nitrogen species. The present invention is described with reference to the following examples, in which titanium beta (Ti-β) or titanium silicalite (TS-1) is used as a catalyst to distillate fuel to hydrogen peroxide. Oxidized in. The preparation of TS-1 catalyst is described in EP 0376453A.

Example 1 The distillate fuel used in Example 1 had the following properties.

[0030]

[Table 2]

[0031]   Bromine number: 1.20 g Br per 100 g sample   The aromatic compound content was 32.9% by weight according to PINA (ASTM D2786).   The sulfur content was 0.52% by weight. Distribution of carbon number by capillary gas chromatography (% by weight)

[0032]

[Table 3]

The fuel had a relatively high sulfur level and bromine number, resulting in high hydrogen peroxide consumption. The titanium beta catalyst used was prepared as follows. A synthesis reactant

[0034]

[Table 4]

[0035] Gel Composition (mole ratio) Si: Al: Ti: OH -: H 2 O = 1: 0.003: 0.018: 0.55: a 15.7 TEAOH201.74G initiate synthesis by placing a plastic container, where Magne it Stir under a stream of nitrogen with a tick stirrer for 10 minutes. After stirring, 100 ml of water was added. Then TPOT was added dropwise with continued stirring. 2.9
g was added over 7 minutes. 1.8 g was added over the next 5 minutes, followed by 0.66 g over 3 minutes. The total time to add a total of 5.36 g of TPOT was 15 minutes. Then 60 g of Aerosil were added: 10 g of each was added in 1/4 hour each, until 50 g of Aerosil was added. At this point, an aqueous solution of Al (NO3) 3 H2O (water 61
0.63 g in 0.1 ml) was added. Finally, the last portion of 10 g of Aerosil was added. The mixture was stirred under a stream of nitrogen for 2 hours. This resulted in a clear, slightly thickened gel, which was heated to 135 ° C. for 2 hours in a Teflon liner PARR autoclave (1 liter). Then autoclave for 240 hours
It was kept at 135 ° C.

Washing and Centrifuging and Drying The solid phase was separated by centrifugation at 9000 RPM for 1 hour. The solid material was crushed, washed 4 times and subjected to a final centrifugation at 11000 RPM for 2 hours.
The material was then dried. Finally, the solid material was calcined under a stream of air. The calcination program was as follows: 30 ° C → 550 ° C (60 ° C / hour) 550 ° C → 550 ° C (24 hours) 550 ° C → 120 ° C (60 ° C / hour) B characterization substances are X-ray powder diffraction, scanning electron microscope, Fourier transform infrared spectroscopy It was analyzed by analysis (UV-VIS spectroscopy). Atomic absorption spectroscopy and photometry (colorimetry) were used for elemental analysis.

C Oxidation Using Ti-β prepared as above and TS-1 prepared according to EP0376453A, the oxidation reaction was carried out at the temperatures shown in Table 1. The method used is US Pat.
The reaction was carried out for 6 hours at reaction temperature with stirring at 520 rpm using the hydrogen peroxide to distillate fuel ratios described in Table 1 below and described in No. 1,607. The properties of the obtained substance are shown in Table 1. Oxygen content is estimated, calculated from NMR data, assuming the composition of the starting distillate fuel to be C ₁₂ H _{2 6.}

[0038]

[Table 5] Table 1

[0039]

[Table 6] Table 1 (continued)

TBA is tertiary butyl alcohol, meaning ND was not detected. The data in Table 1 show how the conversion, oxygen content and acid content are affected by the choice of catalyst, the ratio of materials used, the choice of solvent and reaction conditions. FIG. 1 is an infrared spectrum of an unoxidized mixture of 70% tertiary butyl alcohol and 30% diesel in the wave number range of 500 to 4000, and FIG.
An expanded version of the spectrum at 2000 wavenumbers. 3 and 4 show Experiment 3
5 and 6 are the corresponding spectra for the product of Experiment 8 and FIGS. These spectra clearly show the presence of a carbonyl function with a significant increase in the peak near 1709 and a new peak near 1650, and the use of tertiary butyl alcohol as a solvent masks the indication of alcohol in the oxidized fuel. To do. FIG. 7 is an infrared spectrum of the acetone / diesel mixture used as the feedstock in Experiment 1, using an acetone solvent, and FIG. 8 is a spectrum of the oxidized product of Experiment 1. The peak at 3500 in Figure 8 confirms the formation of hydroxyl groups during oxidation. In this case, acetone masks the indication of carbonyl groups in the oxidized fuel. The spectra for experiments 2, 4, 6 and 7 showed similar effects.

COMPARATIVE EXAMPLE 1 For comparison purposes, experiments 1 and 3 were repeated without catalyst and with titanium dioxide as catalyst. The infrared spectrum of the product showed no formation of carbonyl or hydroxyl groups. Example 2 The amount of fuel produced in Example 1 was too low for engine testing, so
The performance of the fuel containing the hydroxyl-containing material and the carbonyl-containing material expected to be produced in Example 1 is described below as an ultra low diesel fuel (ULS) having the following properties:
Simulated by the addition of various oxygenates to ADO). Density 825 Kg / m ³ KV ₂₀ (cSt) 3.41 Sulfur content 31 ppm T95 314 ° C. Fuel was blended with an appropriate amount of oxygenated material to obtain an oxygen content in the final blend of 2 wt%. Primary alcohol, secondary alcohol, tertiary alcohol and ketone were used. Details of the fuel blend are shown in Table 2.

[0042]

[Table 7] Table 2

The tests were conducted in a VW Golf 1.9 turbo-direct injection engine, which has a needle lift sensor that allows closed loop control of oxidation catalyst, exhaust gas circulation, and injection time mounted very close to the engine block. It is a 1.9 liter supercooled intercooled direct injection engine including an electrically controlled distributor fuel pump with. The fuel blend was tested according to a special test protocol, with daily testing of the base fuel against different test fuels. The base fuel was tested first, followed by the test fuel (which was tested 3 times in succession), followed by the final base fuel test (base 1, test 1, test 2, test 3, base 2). ). Each of these five tests included a thermal ECE + EUDC operating cycle. Gas and particulate emissions were collected for each test.

Results and Description FIG. 9 and Table 3 show the data for the particulate emissions (PM) and NOx emissions measured for each fuel. The bars show a 95% minimum significant difference limit and are said to be significantly different between fuels if they do not overlap. All four oxygenates showed a substantial and significant reduction in particulate emissions over the base ULSADO fuel with an average reduction of 21.9%. There was no statistically significant difference in the amount of particulate reduction seen between the types of oxygenates used. 4 oxygenated blends ULSAD with an average increase of 2.4%
It produced an absolute emission of NOx that was slightly greater than O 2. However, for tertiary alcohols and ketones, these increases were very small and were not statistically significant at the 95% level. Figure 10 and Table 3 show the relative change in emissions of each oxygenated blend compared to the base fuel. Reduction of particulate matter (PM) from 19.8% (tertiary alcohol) to 22.6
% (Primary alcohol & secondary alcohol and ketone). The corresponding increase in NOx emissions over ULSADO is 0.5% (3rd grade), 1.0% (ketone), 3.8% (1st grade)
And 4.4% (secondary grade). The addition of oxygenates to the base diesel fuel also had the effect of increasing hydrocarbon (HC) and carbon monoxide (CO) emissions, which are typical of engine exhaust systems. It can be controlled more easily by using an exhaust oxidation catalyst.

[0045]

[Table 8] Table 3 Difference from ULSADO base [%]

[0046]

[Table 9] Table 3 (continued)

Comparative Example 2 Using the diesel fuel used in Example 1 above, Example 1 of US Pat. No. 5,114,433 and Example 1 of US Pat. No. 5,114,434 were repeated on a 1/10 scale. Analysis of the product mixture showed no indication that the diesel fuel was oxidized.

[Brief description of drawings]

Figure 1: 70% tertiary butyl alcohol and 30% in the wave number range 500-4000
3 is an infrared spectrum of an unoxidized mixture of diesels of.

[Fig. 2]   FIG. 6 is an enlarged view of a spectrum in the wave numbers of regions 1200 to 2000.

[Figure 3]   3 is the corresponding spectrum for the product of Experiment 3.

[Figure 4]   3 is the corresponding spectrum for the product of Experiment 3.

[Figure 5]   9 is the corresponding spectrum for the product of Experiment 8.

[Figure 6]   9 is the corresponding spectrum for the product of Experiment 8.

FIG. 7 is an infrared spectrum of the acetone / diesel mixture used as the feedstock in Experiment 1.

[Figure 8]   2 is a spectrum of an oxidized product of Experiment 1.

FIG. 9 shows data on particulate emissions (PM) and NOx emissions measured for each fuel.

FIG. 10 shows the relative change in emissions of each oxygenated blend compared to the base fuel.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C10L 1/18 C10L 1/18 C Z F01N 3/10 F01N 3/10 Z F02M 27/02 F02M 27/02 A H (81) Designated countries EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE), OA (BF , BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, KE, LS, MW, MZ, SD, SL, SZ , TZ, UG, ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AG, AL, AM, AT, AU, AZ, BA, B, BG, BR, BY, BZ, CA, CH, CN, CR, CU, CZ, DE, DK, DM, DZ, EE, ES, FI, GB, GD, GE, GH, GM, HR, HU , ID, IL, IN, IS, JP, KE, KG, KP, KR, KZ, LC, LK, LR, LS, LT, LU, LV, MA, MD, MG, MK, MN, MW, MX, MZ, NO, NZ, PL, PT, RO, RU, SD, SE, SG, SI, SK, SL, TJ, TM, TR, TT, TZ, UA, UG, US, UZ, VN, YU, ZA , ZW (72) Inventor Dhaka Jihad Mohammed Belgium B 3010 Kesselro Heck Nuttellarn 7 (72) Inventor Yelisa Eye USA New Jersey 08053 Marlton Denver Road 14 F Term (reference) 3G091 AA02 AA18 AB02 BA00 BA15 BA19 4H013 AA01 AA06 BA00 BA02 BA03 4H029 DA01 DA06 DA09

Claims (39)

[Claims] 1. A distillate fuel having a hydroxyl group and / or a carbonyl group chemically bonded to a paraffinic carbon atom in a distillate fuel molecule in an amount that provides at least 0.1% by weight of oxygen in the fuel. 2. The distillate fuel according to claim 1, which contains at least 0.3% by weight of oxygen. 3. The distillate fuel according to claim 1 or 2, wherein 70% or more of oxygen in the distillate fuel molecule is in the form of a hydroxyl group or a carbonyl group. 4. The distillate fuel according to any one of claims 1 to 3, which contains 0.5 to 10% by weight of oxygen. 5. The distillate fuel according to any one of claims 1 to 4, wherein the hydroxyl group is a secondary hydroxyl group and / or a tertiary hydroxyl group. 6. The distillate fuel according to any one of claims 1 to 5, which boils within a range of 150 to 400 ° C. 7. The method according to claim 1, which has a boiling point of 95% by volume of 370 ° C. or less.
The distillate fuel according to any one of paragraphs. 8. The distillate fuel according to claim 6, which has a boiling point of 95% by volume of 360 ° C. or lower. 9. The distillate fuel according to claim 1, which contains less than 350 ppm of sulfur. 10. The distillate fuel according to claim 9, which contains less than 50 ppm of sulfur. 11. A first composition containing less than 11% by weight of a polycyclic aromatic compound.
Item 10. The distillate fuel according to any one of items 10 to 10. 12. A method according to any one of claims 1 to 1, which contains 15% by weight or less of olefin.
The distillate fuel according to any one of item 1. 13. The distillate fuel according to any one of claims 1 to 12, which has a cetane number of more than 50. 14. A distillate fuel according to claim 13 having a cetane number of at least 52. 15. A method according to any one of claims 1 to 14 having a total acid value of less than 1 mgKOH / g.
The distillate fuel according to any one of paragraphs. 16. The distillate fuel according to any one of claims 1 to 15, which contains a cetane improver. 17. The distillate fuel according to claim 1, which contains a dispersant. 18. The distillate fuel according to any one of claims 1 to 17, which contains a lubricity enhancing additive. 19. The distillate fuel according to any one of claims 1 to 18, which contains a low temperature fluidity improver. 20. An automobile diesel fuel, which is the distillate fuel according to any one of claims 1 to 19. 21. A distillate fuel having a hydroxy group and / or a carbonyl group chemically bonded to a paraffinic carbon atom in a distillate fuel molecule in an amount to provide at least 0.1% by weight of oxygen in the fuel is used. To reduce the production of particulate emissions from fuel combustion in diesel engines. 22. The reduction according to claim 21, wherein the distillate fuel comprises at least 0.3% by weight oxygen. 23. The reduction according to claim 21 or 22, paired with the use of an oxidation catalyst for reducing the hydrocarbon and carbon monoxide content of the exhaust gas from a diesel engine. 24. Hydroxyl and / or carbonyl groups bonded to aliphatic carbon atoms in a distillate fuel by selectively oxidizing paraffinic carbon atoms in the distillate fuel and at least 0.1% by weight of the fuel. A selective oxidation method characterized by obtaining an oxygen content. 25. The method of claim 24, wherein the fuel has an oxygen content of at least 0.3% by weight. 26. The method according to claim 24 or 25, wherein the fuel boils in the range of 150 to 400 ° C. 27. Claim 2 wherein the distillate fuel has a sulfur content of less than 300 ppm.
The method according to any one of items 4 to 26. 28. Claim 2 wherein the distillate fuel has a sulfur content of less than 50 ppm.
The method according to item 7. 29. A method according to any of claims 24 to 28 wherein the distillate fuel has an olefin content of less than 15% by weight. 30. The method according to any of claims 24 to 29, wherein the fuel is oxidized by contact with an oxidant in the presence of a titanium and silicon containing catalyst. 31. The method according to claim 24, wherein the fuel is oxidized with hydrogen peroxide.
The method according to any of the items. 32. The method according to claim 31, wherein the fuel is oxidized by contact with hydrogen peroxide at a temperature of 50 to 150 ° C. in the presence of a titanium silicalite catalyst. 33. The method according to claim 31 or 32, wherein hydrogen peroxide is generated in situ. 34. The method of claim 33, wherein a dual catalyst system is used to produce hydrogen peroxide and catalyze the oxidation of the fuel. 35. The method of any of claims 24-34, wherein the selective oxidation occurs in a reactor downstream of a refinery hydrofiner. 36. A method according to any of claims 24 to 35, wherein oxidised sulfur species and / or nitrogen species are removed from the oxidised fuel. 37. The method of claim 36, wherein the removing is by washing. 38. The method of claim 36, wherein the removing is by distillation. 39. The method of claim 36, wherein the removal is by adsorption.