KR20060006890A - Cerium oxide nanoparticles as fuel additives - Google Patents

Abstract

A method of improving the efficiency of a fuel is described which comprises adding to the fuel prior to the introduction of the fuel to a vehicle or other apparatus comprising an internal combustion engine cerium oxide and/or doped cerium oxide and, optionally, one or more fuel additives.

Description

Cerium oxide nanoparticles as fuel additives {CERIUM OXIDE NANOPARTICLES AS FUEL ADDITIVES}

The present invention relates to cerium oxide nanoparticles useful as fuel additives.

Cerium oxide is widely used as a catalyst for three-way converters to remove toxic exhaust emissions and reduce particulate emissions in automobiles. The cerium oxide contained in such a catalyst may act as a chemically active component, releasing oxygen in the presence of a reducing gas and removing oxygen through interaction with elemental oxidized species to serve as an oxygen reservoir.

Cerium oxide can store and release oxygen through the following processes;

2CeO ₂ ↔ Ce ₂ O ₃ + 1 / 2O ₂

The secret is cerium oxide is used as the catalyst object of the present invention is the low redox potential between the Ce ^{3 +} and Ce ^{+ 4} ions that happen to facilitate the reaction in the exhaust gas (1.7V). Cerium oxide can provide oxygen for the oxidation of CO or C _n H _n or absorb oxygen for the reduction of NO _x . The amount of oxygen provided and removed reversibly in the gas phase is called the cerium oxide oxygen storage capacity (OSC).

This catalytic activity can occur when cerium oxide is added as an additive to fuels such as diesel or gasoline. However, in order for this effect to be useful, the cerium oxide must be small enough in particle size to remain stable in fuel. Such cerium oxide particles should be nanocrystalline, such as less than 1 micron in size, preferably in the range from 1 to 300 nm in size. In addition, since the catalytic effect depends on the surface area, these small particle sizes make nanocrystalline materials more effective as catalysts.

Cerium oxide added to the fuel is for at least one purpose. The main purpose is to act as a catalyst to reduce toxic emissions in fuel combustion. However, in diesel engines it can be used for another purpose. Diesel engines are increasingly equipped with traps for particulate matter produced during combustion of diesel fuel. The presence of cerium oxide in this trap aids in the burning of particulate matter accumulated in the trap. In fact, this use is done in industrial operation. That is, certain vehicles, mainly those designed in Peugeot, have an on-board dosing system, whereby cerium oxide is added to the fuel before it enters the engine. However, the system is not only complicated but also requires a wide range of electronic controls to supply the right amount of additives to the fuel. Effective, the embedded system has a particulate filter that can be recycled and can be used for quite some time.

Currently, we have found other uses of the cerium oxide nanoparticles disclosed herein, whereby the cerium oxide nanoparticles are added to the fuel at an earlier stage. It has also been found that the addition of particles in this manner can lead to improved fuel efficiency.

Accordingly, the present invention comprises adding cerium oxide and / or doped cerium oxide and optionally one or more fuel additives to fuel prior to injecting the fuel into a vehicle or other device comprising an internal combustion engine. It provides a method for improving engine fuel efficiency.

When cerium oxide is added in this way, no vehicle needs a fuel management system. Fuel efficiency is seen when the cerium oxide particles are added to the fuel.

Such particles can be added to the fuel at various points in time. Particularly advantageous are the advantages with respect to addition at these various points. In particular, cerium oxide can generally be added in refineries with processing additives. This is, of course, the first time a cerium oxide can be added, meaning that the fuel available in the refinery already contains additives and no longer needs to be added in subsequent steps. It can also be added from the fuel company's storage if necessary, which means that the amount added can be adjusted according to the needs of each fuel company. Alternatively, cerium oxide may be added to storage tanks in public gas station yards or private gas station yards or dispensed into fuel when refueling in vehicles. This approach has the advantage that maximum stabilization of the particle dispersion can be achieved.

Although the main purpose of adding cerium oxide to fuel is to increase fuel economy, it is well known to those skilled in the art that the presence of such particles in the fuel, if equipped, also aids in the regeneration of diesel particulate filters. In other words, the effect of cerium oxide in this case is generally to allow regeneration to take place at lower temperatures. This has the advantage of reducing the likelihood of cracking filters usually made of ceramic material.

Although it is possible to use conventional cerium oxide particles, it has been found to be advantageous to use cerium oxide doped with components that cause additional oxygen vacancies to form. This generally means that the dopant can be divalent or trivalent which provides oxygen vacancies.

These dopant ions must be divalent or trivalent ions of elements that are rare earth metals, transition metals, or metals of Group IIA, IIIB, VB or VIB of the Periodic Table, providing oxygen vacancies. In addition, these dopant ions should be sized to allow for the incorporation of ions within the surface region of the cerium oxide nanoparticles. Therefore, a metal with a large ion radius cannot be used. For example, transition metals in the first and second rows of transition metals are generally preferred over transition metals in the third row. Cerium oxide acts as an oxygen activation and exchange medium during the redox reaction. However, since cerium oxide and the like are ceramic materials, their electrical conductivity is low and the active surface area required for chemisorption of reactive element species is also small. Particularly useful in improving this situation are transition metal additives. In addition, the polyvalent dopants also exhibit a catalytic effect by themselves.

In general, the doped oxide is represented by the formula Ce _1-x M _x O ₂ , where M is the metal or metalloid, specifically Rh, Cu, Ag, Au, Pd, Pt, Sb, Se, Fe , Ga, Mg, Mn, Cr, Be, B, Co, V, Zr, Ti and Ca, as well as Pr, Sm and Gd, x is at most 0.3, generally 0.01 or 0.1 to 0.2), or a formula [ Represented by (CeO ₂ ) _1-n (REO _y ) _1-k ] M ' _k , wherein M' is a metal or metalloid other than rare earths, RE is a rare earth metal, y is 1 or 1.5 n and k may be the same or different, respectively, and are at most 0.5, preferably at most 0.3, generally 0.01 or 0.1 to 0.2). More details can be found in Applicant's PCT application GB2002 / 005013, which is incorporated herein by reference.

In general, the cerium oxide particles have a size of 1 micron or less, in particular 300 nm or less, for example in the range of 1 to 300 nm, specifically 1 to 150 nm, in particular 1 to 50 nm, more particularly 1 to 20 nm.

Such particles are preferably coated to prevent aggregation. To this end, the particles can be ground in an organic solvent in the presence of a coating which is an organic acid, anhydride or ester or Lewis base thereof. It has been found that by the method involving such in-situ coating, the coating of the oxide can be significantly improved. In addition, the product obtained can be used almost immediately without any intermediate step. Thus, some coating procedures require the drying of the particles before the coated particles are dispersed in the hydrocarbon solvent.

That is, cerium oxide can be dispersed or dissolved in fuel (liquid) or other hydrocarbon compatible with the fuel.

Particles treated according to this process should be as large as possible with a surface area of at least 10 m 2 / g, preferably at least 50 or 75 m 2 / g, such as 80 to 150 m 2 / g or 100 to 300 m 2, prior to coating. It is preferably in the / g range.

Suitable coating agents are organic acids, their anhydrides or esters or Lewis acids. Such coatings are preferably organic carboxylic acids such as stearic acid or anhydrides thereof, which generally have at least 8 carbon atoms, such as 10-25 carbon atoms, in particular 12-18 carbon atoms. It will be appreciated that such carbon chains may be saturated or unsaturated chains, such as ethylenically unsaturated chains such as in oleic acid. The same is true for anhydrides that can be used. Such anhydrides are preferably dicarboxylic acid anhydrides, in particular alkenyl succinic anhydrides, specifically dodecenyl succinic anhydride, octadecenyl succinic anhydride and polyisobutenyl succinic anhydride. Other organic acids, anhydrides and esters that may be used in the process of the present invention include those derived from phosphoric acid and sulfonic acid. Esters are generally aliphatic esters and include, for example, alkyl esters in which both the acid and ester moieties have 4 to 18 carbon atoms.

The coating process can be carried out in an organic solvent. Preferably, the solvent is nonpolar and also preferably nonhydrophilic. It may be an aliphatic or aromatic solvent. General examples include toluene, xylene, gasoline, diesel fuels, as well as heavier fuel oils. In essence, the organic solvent used should be chosen to meet the end-use application of the coating particles. Water should be excluded and the use of anhydrides as a coating helps to remove any water present.

The coating process involves grinding the particles such that no aggregates are formed. Techniques that can be used for this purpose include the use of high speed agitation or tumbling and colloid mills, ultrasonic or ball milling. Ball milling is preferred. More details on such coatings can be found in PCT / GB02 / 02312.

In particular, the concentration of cerium oxide added to the fuel may generally be lower than that used in embedded quantitative systems. That is, the concentration of cerium oxide in the fuel is generally 20 ppm or less, typically 10 ppm or less. Generally the minimum concentration is on the order of 1 to 2 ppm.

The particles may be added directly to the fuel or as part of an additive package added to the fuel. In particular, the particles are preferably added to the diesel fuel. The present invention is particularly useful for large vehicles, such as trucks and buses, in which a built-in metering system is generally not equipped. This fuel can also be used in electrostatic engines such as generators.

The nature of the formulation used to add cerium oxide will of course vary depending on the time point at which cerium oxide is added.

In general, it has been found that cerium oxide particles can be stabilized in a fuel or fuel additive package through the presence of a detergent. In this regard, it is evident that the lubricating agent may adversely affect the formation of precipitates. Specific detergents that can be used in the present invention include basic nitrogen-containing detergents. Such detergents must be ashless and contain no metal at all. Suitable detergents include amides, amines, Mannich bases and preferred succinimides. Such detergents are preferably succinimides having an average of at least three nitrogen atoms per molecule. Such succinimides are preferably aliphatic and may be saturated or unsaturated, in particular ethylenically unsaturated, such as alkyl or alkenyl succinimides. Generally, detergents are generally prepared from alkyl or alkenyl succinic acylating agents having at least 35 carbon atoms in the alkyl or alkenyl group and alkylene polyamine mixtures having an average of at least three nitrogen atoms per molecule. Preferably, a polyisobutenyl succinic acylating agent derived from polyisobutene having a number average molecular weight in the range of 500 to 10,000, and an ethylene polyamine having an average composition of triethylene tetramine to pentaethylene hexamine, which may comprise a ring and acyclic moiety It can be prepared as. That is, the chain generally has a molecular weight of 500 to 2500, in particular 750 to 150, in particular a chain having a molecular weight in the range of about 900 to 1300 is particularly useful, but succinimides having aliphatic chains having a molecular weight of about 2100 are also useful. Do. More details can be found in US-A-5,932,525 and 6048373 and EP-A-432,941, 460309 and 1,237,373.

Accordingly, the present invention provides a fuel additive composition containing cerium oxide and / or doped cerium oxide together with a detergent, preferably an aliphatic succinimide.

Generally the concentration of cerium oxide contained in such additives is in the range of 0.1 to 10% by weight, generally 0.5 to 5% by weight.

If cerium oxide is to be added at the refinery, only cerium oxide can be added without virtually any other additives. In general, additives added in oil refineries include cetane number improvers, low temperature flow improvers and antioxidants. Thus, the composition of the present invention may contain one or more such additives. In general, however, cerium oxide does not increase the cetane number, so the additives are less likely to be added together.

If cerium oxide is added in the reservoir, it may be added alone or in combination with other ingredients as set out below, as well as cleaning agents, which are generally added to the fuel at this stage.

If cerium oxide is added in the gas station forecourt, it can be carried out as with the reservoir addition.

Common additives that can be used in fuel compositions, particularly diesel fuels, include the following additives commonly used:

Aromatic and aliphatic hydrocarbons such as nonpolar organic solvents such as toluene, xylene and white spirits, and mixtures thereof. Commercially available products include the Royal Dutch / Shell Group product of the "SHELLSOL" brand and the ExxonMobil group product of the "EXXSOL" brand.

Polar organic solvents , in particular alcohols, in particular aliphatic alcohols such as 2-ethylhexanol, decanol and isotridecanol.

Detergents such as hydrocarbon substituted amines and amides such as hydrocarbon substituted succinimides such as polyisobutenyl succinimide.

Cloudy agent, for example, alkoxylated phenol formaldehyde polymer, for example a commercially available product "NALCO" (trade mark) 7D07 (Nalco, Ltd.), and "TOLAD" (trade mark) there are 2683 (Petrolite Ltd.).

Antifoaming agents such as polyether modified polysiloxanes are commercially available "TEGOPREN" (trademark) 5851 (manufactured by Th. Goldschmidt) Q 25907 (manufactured by Dow Corning) or "RHODORSIL" (manufactured by Rhino Poulenc).

Ignition improvers such as aliphatic nitrates such as 2-ethylhexyl nitrate and cyclohexyl nitrate.

Rust inhibitors such as "RC 4801" commercially available from Rhein Chemie (Mannheim, Germany) or HiTEX® 536 commercially available from Ethyl Corporation, or polyhydric alcohol esters of succinic acid derivatives.

Fragrance

Antioxidants such as phenolic compounds such as 2,6-di-tert-butylphenol or phenylenediamines such as N, N'-di-sec-butyl-p-phenylenediamine.

Metal deactivators such as salicylic acid derivatives such as N, N'-disalicylidene-1,2-propane diamine, and

Lubricating agents such as polar compounds, especially fatty acids, esters and amides thereof. Generally, the acid has a C ₂ to C ₅₀ chain and / or is aromatic, and not only polyhydric acids such as dicarboxylic acids (e.g. dimers of unsaturated acids such as oleic or linoleic acid) but also hydroxy aromatic carboxylic acids. , Especially acids having ortho OH groups, such as salicylic acid, especially acids substituted with groups having at least 10 carbon atoms. Typical esters are such acids and poly (oxyalkylenes) having a C ₁ to C ₅ aliphatic alcohol or a polyhydric alcohol such as glycol, glycerol or pentaerythritol or a poly (oxyalkylene) alcohol, such as five oxyalkylene groups. ) Is derived from alcohol such as alcohol. The ester of polyhydric acid may be a partial ester. Examples of specific esters include salicylic acid esters as well as glycerol mono- and di-esters such as glyceryl monooleate, sorbitan monooleate and pentaerythritol monooleate. Other lubricating agents that may be used include esters and aminoalkylmorpholines derived from carboxyphenols and polyols. Some of these formulations are those sold under the following trademarks as described in WO98 / 01516 and 98/16596: EC831, P631, P633 or P639 (Infinium product) or "HITEC" (trademark) 580 (Ethyl Corporation product), TOLAD 2670 and 9103 from Baker Petrolit.

Emulsifiers such as Baker Petrol as marketed as TOLAD 2898.

Preferred additives are those containing one or more of antifoams, emulsifiers and rust inhibitors.

Unless otherwise indicated, the concentration of each additive (active substance) contained in the fuel is generally up to 1000 ppmw (one millionth by weight of diesel fuel), in particular up to 800 ppmw, such as 1 to 1000 ppmw, 1 to 800 ppmw Or 1 to 20 ppmw.

It is preferable that the concentration of the antifog agent (active substance) contained in the diesel fuel is in the range of 1 to 20 ppmw. Preferably, the concentration of the other additives (except the cleansing agents, ignition improvers and lubricants) (active substance) is at most 20 ppmw each. The concentration of the detergent (active material) is generally in the range of up to 800 ppmw, such as 10 to 500 ppmw. The concentration of the ignition improver (active material) contained in the diesel fuel is preferably in the range of up to 600 ppmw, such as 100 to 250 ppmw. If a lubricious agent is added to the diesel fuel, it is convenient to be used in an amount of 50 to 500 ppmw.

Some of these additives are more commonly added directly (with cerium oxide) in refineries, while others of diesel fuel additives (DFAs) are typically added at the point of filling the tank or at the pump. Common DFAs include the following ingredients:

10 to 70% of detergent (by weight)

Rust preventive 0-10%

Antifoam 0-10%

Cloudiness 0 to 10%

Nonpolar solvent 0-50%

Polar solvent 0-40%

The diesel oil may itself be an additive (containing additive) oil. If the diesel oil is an additive oil, it may contain small amounts of one or more additives such as: antistatic agent, oil pipe blocker reducer, flow improving agent such as ethylene / vinyl acetate copolymer or acrylate / maleic anhydride copolymer, And wax anti-settling agents, such as "PARAFLOW" (eg "PARAFLOW" 450; from Paramins), "OCTEL" (eg "OCTEL" W5000; Octel) and "DODIFLOW" (eg "DODIFLOW" V3958; Hoechst) Products marketed under the trademark.

As will be appreciated by those skilled in the art, the same or similar additives may be used for other fuels such as gasoline.

The following examples are intended to illustrate the invention in more detail:

The sedimentation of the fuel containing cerium oxide alone or in combination with other additives was examined to obtain the following results:

One 2% cerium oxide in aliphatic solvent 48.0% Shellsol d70 52.0% aliphatic solvent Significant solid separation after 24 hours 2 2% cerium oxide in aliphatic solvent 48.0% HiTEC 4620 Aliphatic solvent containing 52.0% detergent and antifoam Slight solid separation after 24 hours 3 2% cerium oxide in aliphatic solvent 48.0% BASF Keropur DP403 Aliphatic solvent 52.0% containing detergent and antifoam Slight solid separation after 24 hours 4 2% cerium oxide in aliphatic solvent 48.0% Octel DFA Aliphatic solvent 52.0% containing detergents, antifoams and preservatives No solid separation after 24 hours

Claims (42)

Prior to injecting fuel into a vehicle or other device comprising an internal combustion engine, the fuel efficiency of the internal combustion engine may be improved, including the step of adding cerium oxide and / or doped cerium oxide and optionally one or more fuel additives. How to improve. The method of claim 1 comprising adding a cerium oxide doped with a divalent or trivalent metal or metalloid which is a rare earth metal, transition metal or metal of Groups IIA, IIIB, VB or VIB of the Periodic Table. A method for improving fuel efficiency of an internal combustion engine. The method of claim 2, wherein the metal is a transition metal. The method of claim 3, wherein the metal is rhodium, copper, silver, gold, palladium, platinum, iron, manganese, chromium, cobalt, vanadium, zirconium, or titanium. The method of claim 1 or 2, wherein the metal is terbium, preseodymium, samarium, gadolinium, antimony, selenium, gallium, magnesium, beryllium, boron, or calcium. . 6. The method of claim 1, wherein the cerium oxide and / or the doped cerium oxide does not exceed 1 micron in size. 7. 7. The method of claim 6, wherein the cerium oxide and / or the doped cerium oxide range in size from 1 to 300 nm. 8. The fuel efficiency of an internal combustion engine according to claim 1, wherein the cerium oxide and / or the doped cerium oxide is coated with an organic acid, anhydride, ester, or Lewis base thereof. 9. Way. The method of claim 8, wherein the coating is a dicarboxylic acid anhydride coating. 10. The method of claim 9, wherein the coating is an alkenyl succinic anhydride coating. The method of claim 10, wherein the succinic anhydride is dodecenyl succinic anhydride, octadecenyl succinic anhydride, or polyisobutenyl succinic anhydride. The method according to any one of claims 1 to 11, wherein the fuel is a diesel fuel. The method of claim 1, wherein the cerium oxide and / or the doped cerium oxide is added together with a solvent that is an aliphatic or aromatic hydrocarbon or an aliphatic alcohol. Way. 14. A method according to any one of the preceding claims, wherein cerium oxide and / or doped cerium oxide are added to the fuel in the refinery. 14. A method according to any one of the preceding claims, wherein cerium oxide and / or doped cerium oxide are added in the fuel reservoir. 14. A method according to any one of the preceding claims, wherein cerium oxide and / or doped cerium oxide are added in the filling station forecourt. The method of claim 1, wherein the cerium oxide and / or doped cerium oxide is a detergent, antifog, antifoam, ignition improver, rust inhibitor, fragrance, antioxidant, metal deactivator, lubricity agent or emulsifier. A method for improving fuel efficiency of an internal combustion engine, characterized in that it is added together with at least one of the destructive agents. 18. The method of claim 17, wherein cerium oxide and / or doped cerium oxide is added together with the detergent. 19. The method of claim 18, wherein the detergent is a basic nitrogen-containing ashless detergent. 20. The method of claim 19, wherein the detergent is succinimide having an average of at least three nitrogen atoms per molecule. The mixture of claim 20 wherein the succinimide is from an alkyl or alkenyl succinic acylating agent having at least 35 carbon atoms in the alkyl or alkenyl moiety and an alkylene polyamine mixture having an average of at least three nitrogen atoms per molecule. Which is directed to improving the fuel efficiency of an internal combustion engine. 21. The polyisobutenyl succinic acid acylating agent of claim 20, wherein the succinimide can be obtained from polyisobutene having a number average molecular weight in the range of 500 to 10,000, and from ethylene polyamine having an average composition of triethylene tetramine to pentaethylene hexamine. Which is directed to improving the fuel efficiency of an internal combustion engine. 22. The method of claim 21, wherein the aliphatic chain of succinimide has a molecular weight in the range of 500 to 2500. 24. The method of claim 23, wherein the aliphatic chain of succinimide has a molecular weight in the range of 750-1500. 25. The method of any of claims 18 to 24, wherein cerium oxide and / or doped cerium oxide is added together with at least one of an antifoaming agent, an emulsifying breaker or a rust inhibitor. Way. 26. The method of any one of claims 1 to 25, wherein cerium oxide and / or doped cerium oxide is added at a concentration not exceeding 20 ppm. 27. The method of claim 26 wherein cerium oxide and / or doped cerium oxide is added in an amount of no greater than 10 ppm. The method of claim 1, wherein the fuel efficiency of the internal combustion engine is substantially as described above. A fuel additive containing cerium oxide and / or doped cerium oxide and a detergent. 30. The fuel additive of claim 29, wherein the concentration of cerium oxide and / or doped cerium oxide is in the range of 0.1 to 10% by weight. 31. The fuel additive of claim 30, wherein the concentration of cerium oxide and / or doped cerium oxide is in the range of 0.5 to 5% by weight. 32. The fuel additive of any one of claims 29-31, wherein the cerium oxide is cerium oxide as defined in one or more of claims 2-11. 33. The fuel additive of claim 32, wherein the detergent is a basic nitrogen-containing ashless detergent. 34. The fuel additive of claim 33, wherein the detergent is succinimide having an average of at least three nitrogen atoms per molecule. 35. The process of claim 34 wherein the succinimide is derived from an alkyl or alkenyl succinic acylating agent having at least 35 carbon atoms in the alkyl or alkenyl moiety and an alkylene polyamine mixture having an average of at least three nitrogen atoms per molecule. Fuel additive. 35. The polyisobutenyl succinic acid acylating agent of claim 34, wherein the succinimide can be obtained from polyisobutene having a number average molecular weight in the range of 500 to 10,000, and from ethylene polyamine having an average composition of triethylene tetramine to pentaethylene hexamine. Fuel additive. 36. The fuel additive of claim 35, wherein the aliphatic chain of succinimide has a molecular weight ranging from 500 to 2500. 38. The fuel additive of claim 37, wherein the aliphatic chain of succinimide has a molecular weight ranging from 750 to 1500. 39. The composition of any one of claims 32 to 38, further comprising one or more of an antifog, antifoam, ignition improver, rust inhibitor, fragrance, antioxidant, metal deactivator, lubricity agent or emulsion breaker. It is characterized by fuel additives. 40. The fuel additive of claim 39, which contains one or more of antifoams, rust inhibitors or emulsion breakers. 43. The fuel additive according to any one of claims 29 to 42, containing a solvent which is an aliphatic or aromatic hydrocarbon or an aliphatic alcohol. 30. The fuel additive of claim 29 substantially as described above.