HK1114875B - Reduced-emissions combustion utilizing multiple-component metallic combustion catalyst - Google Patents

Description

Reduced emission combustion using multi-component metal combustion catalysts

Background

The present invention relates to novel compositions and novel methods for improving the efficiency of fossil fuel combustion sources. The use of a fuel containing a fuel-soluble catalyst comprising platinum and at least one additional metal reduces the production of pollutants of the type produced by incomplete combustion, such as particulates, unburned hydrocarbons and carbon monoxide.

Diesel engines have a number of important advantages over otto-type engines. Among them fuel economy, ease of maintenance and long life. However, from an emissions perspective, they present a more serious problem relative to their spark-ignition counterparts. Emission issues relate to particulates, oxides of nitrogen (NOx), unburned Hydrocarbons (HC), and carbon monoxide (CO). NOx emissions tend to increase as engine operating improvements are made to reduce particulates and unburned hydrocarbons in diesel engines.

Aftertreatment devices, such as Diesel Particulate Filters (DPFs) and Diesel Oxidation Catalysts (DOCs), have been proposed to reduce the emissions of particulates, as well as gaseous hydrocarbons and carbon monoxide, from diesel engines. These devices are under tremendous pressure in older engines and need improvement in efficiency in newer engines. In all cases, they are expensive, mainly due to the cost of the precious metals used, which is required for effectiveness. It is desirable to reduce the cost of a DOC or DPF device or to eliminate them altogether.

It is believed that one way to achieve this is to employ a Fuel Borne Catalyst (FBC); however, they are not entirely effective when used at higher levels. FBCs produce ash and data published under the european VERT program show that at high FBC dose rates of 20ppm, or 100ppm, cerium the number of ultra-fine particles increases significantly above baseline. However, there is no significant increase in the number of ultrafine particles for a bimetal used at 0.5/7.5 or 0.25/4 ppm. It has been found that at low levels of FBC, there is no separate ultrafine oxide particle peak and the metal oxide is contained in the soot over the entire particle size distribution. It is desirable to reduce the contribution of metallic ash to overall engine emissions. Particulate emissions were limited to 100000 micrograms/hp-hr (0.1 grams/hp-hr) for engines meeting 1998 US emission standards. The cerium FBC used at 30ppm in the fuel represents the metal catalyst input load of the engine of 6000 micrograms/hp-hr of metal or approximately 6% of untreated engine emissions.

There is a need to provide diesel fuels containing FBCs that are lower than the existing levels, yet have a high effect such that by reducing the emissions of particulates, HC and CO directly from the diesel engine, the after-treatment equipment can be eliminated or reduced in size, catalyst loading or soot cleaning frequency.

Disclosure of Invention

An advantage of the present invention is that improvements can be achieved without the use of after-treatment devices such as filters or catalysts, for example a Diesel Particulate Filter (DPF) or a Diesel Oxidation Catalyst (DOC) in the case of a diesel engine.

Another advantage of the present invention is that for engine out emissions from diesel engines, improvements can be achieved to the extent that if an aftertreatment device such as a DOC or DPF is applied, the device can use less precious metals with improved performance.

Fuels for use in accordance with the present invention include carbonaceous fuels (e.g., fossil fuels) having low or ultra-low levels of catalyst metal additives. The catalyst is preferably soluble or dispersible in fuel and contains platinum and a cerium and/or iron composition.

In one aspect, the present invention provides a diesel fuel for powering a diesel engine with reduced particulate emissions without the need for aftertreatment devices, comprising: a base fuel (basic fuel) comprising distillate (distillate), and a fuel borne catalyst comprising platinum and cerium and/or iron, wherein platinum is used at a level of 0.05 to 0.5ppm, such as 0.1 to 0.5ppm, and cerium and/or iron is used at a level of 5 to 10 ppm. Preferably, the diesel fuel contains less than 0.05% sulfur. In a preferred aspect, cerium and/or iron are present in a total concentration of 0.5 to less than 8 ppm.

In another aspect, the present invention provides a method for reducing emissions of particulates, hydrocarbons and carbon monoxide from a diesel engine directly output from the engine prior to contact with an oxidizer or particulate trap (particulate trap), comprising: adding a fuel soluble platinum group metal composition and a further catalytic compound comprising at least one of a fuel soluble cerium and/or iron compound to a diesel fuel to reduce emissions of particulates, unburned hydrocarbons and carbon monoxide, wherein platinum is used at a level of 0.05 to 0.5ppm, for example 0.1 to 0.5ppm, and cerium and/or iron is used at a level of 5 to 10 ppm; and operating a diesel engine with the fuel.

Viewed from another perspective, the invention may be described as providing a method for improving the combustion of a pilot fuel in a dual fuel diesel engine operating primarily on natural gas, comprising: a multi-component catalyst composition is added to the pilot fuel, the composition comprising platinum in a concentration of only 0.0005 to less than 0.15ppm and cerium and/or iron in a total concentration of only 0.5 to less than 8 ppm.

Viewed from a further perspective, the invention is viewed as providing a process for combusting carbonaceous fuel comprising: mixing fuel or combustion air with a multi-component combustion catalyst comprising a platinum composition and a cerium and/or iron composition, the level being reduced to as low as 0.0005ppm for platinum and as low as 0.5ppm for cerium and iron; and combusting the fuel with air in the presence of the catalyst in a treatment regime that utilizes an effective catalyst level at times and conditions to achieve one or more significant improvements.

In another aspect of the present invention, there is provided a method for combusting carbonaceous fuel, comprising: mixing fuel or combustion air with a multi-component combustion catalyst comprising a platinum composition and a cerium and/or iron composition at a level of about 0.0005 to 2ppm for platinum and about 1 to 25ppm for cerium and iron; and combusting the fuel with air in the presence of the catalyst in a treatment regime that utilizes an effective catalyst level at times and conditions to achieve one or more significant improvements; the amount of catalyst used is then varied for at least some time by: mixing fuel or combustion air with a multi-component combustion catalyst comprising a platinum composition and a cerium and/or iron composition, the level being reduced to as low as 0.0005ppm for platinum and as low as 0.5ppm for cerium and iron; and combusting the fuel with air in the presence of the catalyst in a treatment regime that utilizes an effective catalyst level at times and conditions to achieve one or more significant improvements.

In addition, the present invention provides a method for combusting carbonaceous fuel, comprising: for at least a portion of the treatment, higher catalyst concentrations are used, such as 0.5 to 2.0ppm for platinum and 7.5 to 15ppm for cerium; mixing the fuel with a multi-component combustion catalyst comprising a platinum composition and a cerium and/or iron composition at a level of from 0.0005 to less than 0.15ppm for platinum and from 0.05 to less than 1.0ppm for cerium and iron; and combusting the fuel with air in a manner that achieves one or more significant improvements.

A number of preferred aspects of the invention are described below. Equivalent combinations are conceivable.

Drawings

The invention will be better understood and its advantages will become more apparent from the description set forth below, particularly when read with reference to the accompanying drawings, in which:

FIG. l is a graph summarizing the data in example 3, wherein platinum/cerium Fuel Borne Catalyst (FBC) at low concentrations was evaluated on a diesel engine with several fuels.

FIG. 2 is a graph summarizing the data in example 6, wherein platinum/cerium Fuel Borne Catalyst (FBC) at low concentrations was evaluated on a diesel engine with several fuels.

FIG. 3 is a graph summarizing the data in example 7, wherein platinum/cerium Fuel Borne Catalyst (FBC) at low concentrations was evaluated on a diesel engine with several fuels.

Detailed Description

In addition to other advantages and improvements of the present invention, the use of low and extremely low, individual and combined catalyst levels is significant in several respects, including a substantial reduction in catalyst solids that may accumulate or otherwise fail within the system. The present invention can reduce contaminants without the use of post-treatment equipment and can enhance post-treatment due to reduced particulate generation and increased ability to burn off carbon deposits. Cerium and iron levels were reduced to levels as low as 0.05ppm and platinum levels were reduced to levels as low as 0.0005 ppm. The treatment regime utilizes effective levels in the low and very low ranges for a period of time and under conditions to achieve one or more significant improvements.

As noted above, the present invention relates to the improved combustion of diesel fuels, which typically comprise fossil fuels, such as any common petroleum-derived fuel including distillate fuels. The diesel fuel may be any of the formulations disclosed in the above-mentioned prior patent applications, the entire contents of which are incorporated herein by reference. The fuel may be one or a blend of fuels selected from distillate fuels including diesel fuels, e.g. No.1 diesel fuel, No.2 diesel fuel, Jet fuels, e.g. Jet a, or those having a similar boiling point and viscosity as No.1 diesel, ultra low sulfur diesel fuel (ULSD) and biologically derived fuels, such as those comprising a "monoalkyl ester based oxygenated fuel", i.e. fatty acid esters, preferably methyl esters of fatty acids derived from triglycerides, e.g. soybean oil, rapeseed oil and/or tallow.

JetA and No.1 diesel are considered equivalent For the application of the present invention, but are covered by different American Society For Testing and Materials (ASTM) specifications. The Diesel Fuel is covered by ASTM D975, "Standard Specifications for Diesel Fuel Oils". Jet A has the specifications of ASTM D1655, "Standard Specifications for Aviation Turbine Fuels". The term Ultra Low Sulfur Diesel (ULSD) means No.1 or No.2 diesel fuel having a sulfur level of no more than 0.0015 weight percent (15ppm) and requiring low aromatics content, e.g., less than 10 volume percent, in certain jurisdictions.

The term low aromatics ultra low sulfur diesel (LA ULSD) fuel as used herein means that such fuel component has an aromatics content of less than 10% by volume, and preferably in the range of 1 to 8%, especially in the range of 2 to 5%. The following table shows the common analytical compositions of No.2 diesel and low aromatic ultra low sulfur diesel LA ULSD, and a formulation that also contains a biodiesel component (LA ULSD with FBC and 20% biodiesel).

Diesel from biological sources is known in the art as "biodiesel". Biodiesel typically comprises a minor proportion of the diesel fuel blend, typically about 1-35%, for example, about 15-25%. The blend typically contains about 20% biodiesel, of whichSuch biologically derived fuel components include "mono-alkyl ester based oxygenated fuels", i.e., fatty acid esters, preferably fatty acids derived from triglycerides, such as soybean oil, canola oil, and/or tallow. The term "fatty acid ester" as used herein is intended to include any compound in which the alcohol moiety is readily removed, including polyols and substituted alcohols and the like, but is preferably a volatile alcohol, e.g., C₁-C₄Esters (preferably methyl esters) of alcohols, 2-methoxyethyl and benzyl esters of fatty acids containing about 8 or more (e.g., 8 to 22) carbon atoms, and mixtures of such esters. Volatile alcohols are highly desirable. Methyl esters are the most preferred ester reactants. Suitable ester reactants may be prepared by the reaction of diazoalkanes and fatty acids, or from the alcoholysis of naturally occurring fatty acids in fats and oils.

Suitable fatty acid esters may be derived from synthetic or natural, saturated or unsaturated fatty acids and include positional and geometric isomers. Suitable preferred saturated fatty acids include caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, isomyristic acid, isotelic acid, myristic acid, caprylic acid, and anteisoarachidic acid (anteisoarachidic). Suitable preferred unsaturated fatty acids include myristoleic acid, palmitoleic acid, ricinoleic acid, linoleic acid, oleic acid, elaidic acid, linolenic acid, eleasteric acid, arachidonic acid, erucic acid, and erythrogenic acid. Fatty acid mixtures from soybean oil, palm oil, safflower oil, rapeseed oil, canola oil (low erucic acid), and corn oil are particularly preferred for use in the present invention. The fatty acids can be used directly, and/or after hydrogenation, and/or after isomerization, and/or after purification. For example, rapeseed is C₂₂Fatty acids provide a good raw material; c₁₆-C₁₈The fatty acid may be provided by tallow, soybean oil, or cottonseed oil; and shorter chain fatty acids may be provided by coconut, palm kernel, or babassu oil. Lard, olive oil, peanut oil, sesame oil, and sunflower oil are other natural sources of fatty acids.

Preferred esters for inclusion in biodiesel are lower alkyl esters, for example, the methyl, ethyl, propyl and butyl esters, especially the methyl ester, of soy and/or tallow fatty acids. The following is a specification for Biodiesel (B100) set by the National Biodiesel commission (National Biodiesel Board) in month 12 of 2001, which was also adopted to clarify and define the present invention. Thus, biodiesel is defined as a mono-alkyl ester of a long chain fatty acid derived from vegetable oils or animal fats, for use in compression-ignition (diesel) engines. This specification applies to pure (100%) biodiesel prior to use or blending with diesel fuel. There is a great deal of experience in the united states for a 20% blend of biodiesel with 80% diesel fuel (B20). While biodiesel (B100) can be used, blends with greater than 20% of diesel fuel should be individually evaluated until further experience is available. Equivalents having the same basic function and those varying compositionally up to 50%, preferably less than 20%, may also be employed. In some cases, as little as 2% biodiesel may be used with a blend of 98% diesel fuel from one of the other feedstocks mentioned above.

¹Adjustment of individual constraints to meet specific operating conditions may be achieved between the buyer, seller and manufacturer.

One such product is available under the trademark BioDiesel from members of the national BioDiesel Committee and is identified as "methyl soyate, methyl rapeseed oil fatty acid (RME), methyl bovine fatty acid. The fuel is also referred to by the manufacturer as a "mono-alkyl ester based oxygenated fuel, a fuel derived from vegetable oils or animal fats". It is said to contain 11% by weight of oxygen. They described the product as a methyl ester from a lipid source, CAS number 67784-80-9.

The process of the present invention employs a fuel-soluble, multi-metallic catalyst that preferably comprises fuel-soluble platinum, or one of cerium and iron, or both cerium and iron. Cerium and/or iron are typically used at concentrations of 0.5 to 20ppm and platinum at 0.0005 to 2ppm, with preferred levels of cerium and/or iron being 5 to 10ppm, for example 7.5ppm, and platinum at levels of 0.0005 to 0.5ppm, for example less than 0.15ppm, and in some cases less than 0.1ppm, say 0.01 to 0.09 ppm. In certain embodiments, the treatment regime may require the use of higher catalyst concentrations initially or at defined intervals or when required, but not necessarily for all treatments in the past. In some cases, platinum concentrations can be as high as 1ppm or even as high as 2ppm, when desired. For normal operation, preferred levels of cerium and/or iron are 2 to 10ppm, e.g., 3 to 8ppm, and platinum is used at levels of 0.05 to 0.5ppm, e.g., 0.1 to 0.5ppm, e.g., 0.15 ppm. The following tests conducted at these levels showed surprising results in terms of engine out emissions.

The preferred ratio of cerium and/or iron to platinum is from 100,000: 1 to 3: 1, for example in the range 100: 1 to 20,000: 1, but typically from 50,000: 1 to 500: 1. Preferred ratios within the above ranges and which have been tested to be surprisingly effective have cerium and/or iron to platinum ratios of from 75: 1 to 10: 1. Formulations using 0.15ppm of platinum with 10ppm of cerium and 5ppm of iron are mentioned. In addition, a preferred formulation contains 0.15ppm of platinum and 7.5ppm of iron. Another advantage of low levels of catalyst (about 3-15 ppm total), preferably below 12ppm and more preferably below 8ppm, is that the ultra-fine particles from the metal oxide emissions are reduced. The published data under the european VERT program show that at high FBC dose rates of 20ppm, or 100ppm, cerium the number of ultra-fine particles increases significantly above baseline. However, there is no significant increase in the number of ultrafine particles for a bimetal used at 0.5/7.5 or 0.25/4 ppm. It has been found that at low levels of FBC, there is no separate ultrafine oxide particle peak and the metal oxide is contained in the soot throughout the particle size distribution. A further advantage of the low dose rates specified by the present invention is that the distribution of metallic ash is reduced for the entire engine emissions. For an engine meeting 1998 US emission standards, particulate emissions are limited to 100,000 micrograms/hp-hr (0.1 grams/hp-hr). The cerium FBC used at 30ppm in the fuel represents the metal catalyst input load of the engine of 6000 micrograms/hp-hr of metal or approximately 6% of untreated engine emissions. Thus, the low level catalyst used in the present invention as a bimetallic or trimetallic FBC of less than 8ppm and preferably 4ppm, for example, contributes only a catalyst load of 800 to 1600 micrograms/horsepower-hour to the engine, or 0.8 to 1.6% of the baseline soot emissions. This has the advantage of reduced emissions of metallic ash, and reduces the contribution of the FBC to the total particulate matter emissions or the load of the metallic ash on downstream emission control equipment.

The fuel may contain detergents (e.g., 50 to 300ppm), lubricity additives (e.g., 25 to about 500ppm), other additives, and suitable fuel-soluble catalyst metal compositions, such as 0.1 to 2ppm fuel-soluble platinum group metal compositions, such as platinum COD or platinum acetylacetonate, and/or 2 to 20ppm fuel-soluble cerium or iron compositions, such as cerium as a soluble compound or suspension, cerium octoate, ferrocene, iron oleate, iron octoate, and the like. The defined fuels are combusted without special requirements for other process equipment, but they can be used in particular for a higher level of control of diesel engines.

The combination of low concentrations of platinum with cerium and/or iron in the fuel has the same effect in reducing carbon or soot deposits or emissions as higher concentrations of cerium, iron or other metals without platinum. The metal concentration of several ppm in the combination has the same effect as the cerium and/or iron used alone of 30 to 100 ppm.

In one aspect, the method of the invention comprises: mixing fuel or combustion air with a multi-component combustion catalyst comprising a platinum composition and a cerium and/or iron composition, the level being reduced to as low as 0.0005ppm for platinum and as low as 0.5ppm for cerium and/or iron; and combusting the fuel with air in the presence of the catalyst in a treatment regime that utilizes an effective catalyst level at times and conditions to achieve one or more significant improvements. In one aspect, low catalyst levels may be employed for at least a portion of the treatment regimen, which may also include employing higher initial doses and/or intermittently employing higher catalyst levels.

The present invention also has a significant beneficial use in the field of dual fuel diesel engines, which, although they operate primarily on natural gas, utilize a more smoke-producing pilot fuel such as a conventional diesel fuel. In some cases, the catalyst concentration according to the invention may be the above-mentioned low catalyst level for at least a portion of the treatment regime, wherein the platinum concentration is only 0.0005 to less than 0.15ppm, for example less than 0.1ppm, and the total concentration of cerium and/or iron is only 0.5 to less than 8 ppm. In some cases, it is beneficial to use less than 0.05ppm platinum and a total catalyst level of less than 5 ppm.

These bimetallic and trimetallic platinum combinations are compatible with standard additive components for distillate and residual fuels such as pour point depressants, antioxidants, corrosion inhibitors, and the like.

Specific cerium compounds are: cerium III acetylacetonate, cerium III naphthenate (cerium III napthenate), cerium octoate, cerium oleate and other soaps such as stearates, neodecanoates, and others₆～C₂₄Alkanoic acids, and the like. Many cerium compounds satisfy the formula: ce (OOCR)₃Wherein R ═ hydrocarbon, preferably C₂～C₂₂And include aliphatic, cycloaliphatic, aryl, and alkaryl groups. The preferred concentration of cerium is 1 to 15ppm cerium w/v of the fuel, for example 4 to 15 ppm. Preferably, the cerium is provided as a cerium hydroxy oleate propionate complex (40% by weight cerium) or cerium octoate (12% by weight cerium). Preferred levels are toward the lower end of the range.

Specific iron compounds are: ferrocene, iron-and ferrous acetyl acetonates, iron soaps such as octanoates and stearates (generally, commercially available as Fe (III) compounds), iron naphthenate (ironnapthenate), iron resinate and othersC₆～C₂₄Alkanoic acid, iron pentacarbonyl Fe (CO)₅And the like.

Any platinum group metal composition, such as 1, 5-cyclooctadieneplatinum biphenyl (platinum COD) described in U.S. patent nos. US4,891,050 to Bowers et al, US5,034,020 to Epperly et al, and US5,266,083 to Peter-Hoblyn et al, may be used as the platinum source. Other suitable platinum group metal catalyst compositions include commercially available or readily synthesized platinum group metal acetylacetonates, including substituted (e.g., alkyl, aryl, alkaryl substituted) and unsubstituted acetylacetonates, platinum group metal dibenzylidene acetonates, and fatty acid soaps of tetraamine platinum metal complexes, such as tetraamine platinum oleate. The preferred concentration of platinum is 0.05 to 2.0ppm platinum w/v (milligrams per liter) of the fuel, for example, up to about 1.0 ppm. Preferred levels are towards the lower end of this range, e.g. 0.15 to 0.5 ppm. Platinum COD is the preferred form of platinum added to the fuel. Cerium or iron is typically used at concentrations providing 0.5 to 25ppm of metal and 0.0005 to 2ppm of platinum, with preferred levels of cerium or iron being 5 to 10ppm, such as 7.5ppm, and platinum being used at levels of 0.1 to 0.5ppm, such as 0.15 ppm. The preferred ratio of cerium and/or iron to platinum is from 100,000: 1 to 10: 1, for example from 50,000: 1 to 500: 1. It is exemplified that 0.0015ppm platinum is used, as well as 10ppm cerium and 5ppm iron, wherein the ratio of the sum of cerium and iron to platinum is about 10,000: 1. An alternative exemplary composition contains 0.0015ppm platinum with 10ppm iron and 5ppm cerium. Another composition contains 3 to 10ppm of a combination of Ce and Fe, and 0.1 to 0.5ppm of platinum. Another preferred fuel contains 0.05 to 0.5ppm platinum and 0.5 to 10ppm levels of cerium and/or iron, particularly wherein the cerium and/or iron are present in a total concentration of 3 to 8 ppm.

The combustion according to the invention may be of an emulsion with water, wherein the oil phase is emulsified with water, the water comprising 1-30% water based on the weight of the diesel fuel. In a preferred form, the emulsion is predominantly water-in-oil and preferably contains, in addition to the other components described above, surfactants, lubricity additives and/or corrosion inhibitors. Suitable emulsion forms and additives are discussed in US5,743,922. Combustion can improve combustion efficiency and reduce particulates without the use of oxidation catalysts or particulate filters for enhanced emission control on diesel engines. In addition, better carbon combustion in open flame combustion sources will result in less carbon deposition on heat exchanger surfaces and lower soot oxidation temperatures on downstream heat recovery equipment.

The fuel of the invention, comprising a base fuel and a low level of fuel borne catalyst based on platinum and cerium and/or iron compounds, provides better engine out emissions relative to the prior art when used with an aftertreatment device such as a Diesel Oxidation Catalyst (DOC) or a Diesel Particulate Filter (DPF) in PM, HC, CO, NOx and NO as a percentage of NOx₂The aspects further provide unexpectedly good results. Other devices including particulate reactors, partial pressure filters, or NOx adsorbers may also be used and benefit from the reduced engine out emissions of the present invention. The term "diesel particulate filter" is meant to denote those devices known in the art for use as exhaust filters, which reduce particulate emissions by trapping a portion of the particulates within a complex internal structure. Since deposits can accumulate, they must be regenerated or replaced. They may be of any suitable construction such as ceramic, metal, SiC or wire mesh. The term "diesel oxidation catalyst" is meant to refer to those devices known in the art for use as gas treatment catalysts that reduce the emissions of particulates, hydrocarbons, and carbon monoxide by replacing the trapping of particulates in a diesel particulate filter with contact with a catalyzed surface. Reducing NO for engine output results and with catalyzed aftertreatment devices₂And the benefits of FBC with particulate emissions, see the examples below. While not wishing to be bound by theory, the aftertreatment devices and engine out emissions achieved unexpectedly good results, which may be because platinum was not sufficient to produce excess NO₂Is present and still produces some NO in the presence of low levels of cerium and/or iron₂Or other chemical sufficient to promote oxidation of carbon in the particulates. NO₂Is a strong lung irritant, and may beAre produced in large quantities by means of conventionally used re-catalyzed after-treatment devices such as DOC, DPF or combinations thereof. Limited NO due to low platinum concentration and cerium and/or iron being present in low but sufficient amounts₂The net result is that much greater than expected reductions in particulates (and other species resulting from incomplete oxidation) are produced, while at the same time controlling the production and release of NO₂The amount of (c). Unlike the prior art, the present inventors have found that high NO₂The rate of production is not essential and in essence a way has been found to provide emissions that are less irritating to humans.

The following examples are provided to further explain and illustrate the invention and should not be taken as limiting in any way. All parts and percentages are by weight unless otherwise indicated.

Example 1

This example describes the preparation of a low emission diesel fuel according to a preferred aspect of the present invention, using an alternative grade 55 Jet kerosene (Jet a, boiling point and viscosity similar to No.1 diesel) from the above analyzed chenille Pipeline Company (colonal Pipeline Company), blended with an additive (100ppm TFA 4690-C detergent, 225ppm of the Texaco lubricity additive) and a Fuel Borne Catalyst (FBC) containing 0.15ppm platinum provided as platinum COD and 7.5ppm cerium provided as cerium hydroxy oleate propionate complex (a solution containing 40 wt% cerium). These ppm values are again the weight of metal in milligrams per volume of fuel in liters. This fuel was tested on a 400 horsepower engine of 1998 DDC Detroit Diesel Series 60 and showed significantly improved results relative to the No 2 fuel or CARB ULSD (California Air Resources Board Ultra Low Sulfur Diesel fuel) fuel for the highway as a reference.

The test results are summarized in the table below, where the test results for FTP transient-composite results are given for the various fuels tested.

The CARB ULSD fuel has been the subject of much attention for research and development, but these results are surprising from such a standpoint, as they still do not provide improved results as compared to the present invention with FBC catalysts containing low levels of platinum and cerium. The present invention thus provides a very practical way of reducing the range of polluting emissions without creating the need for difficult and expensive treatments to achieve ultra low sulphur levels, which are currently considered essential for particle control.

Example 2

This example gives the results of platinum and cerium bimetallic FBCs used at a total of 4ppm in a commercial ultra low sulfur diesel engine versus a conventional sulfur fuel and a reference ULSD, and the results of tests conducted on a 1998 DDC Series 60 engine. The results are summarized in the following table:

emission results in 1998 DDC Series 60 engines on various fuels

(repeat Hot FTP test)

The table above shows the improvement in HC (54%), NOx (5%), PM (25%) and fuel economy (1.4%) for FBC treated fuels relative to the unadditized reference ULSD.

Example 3

Three 20 minute thermal transient test cycles were performed on a 1990 DTA-466 International 7.6 liter engine. NOx, NO and NO measured in gram/horsepower-hours₂And the average emissions of the particulates are shown in the table below.

Standard emissions for commercial No.2D (> 300ppm sulfur) and ULSD (< 15ppm sulfur) show similar NO₂Emissions, as a percentage of total NOx species, were 17 and 18% of total nitrogen species. The particles were slightly lower for ULSD, 0.244 grams/hp-hr.

Installation in an exhaust device having a 75g/ft³PGM-loaded heavy-duty catalytic diesel oxidation catalyst (HCDOC) and catalyst having 14g/ft³A Lightly Catalyzed Wire Mesh Filter (LCWMF) with Platinum Group Metal (PGM) loading used with bimetallic platinum/cerium FBC at 0.5/7.5ppm in ULSD fuel produced 59% particulate reduction but increased NO₂Emissions reach 58% of total nitrogen oxide species. The cerium additive was cerium hydroxy propionate oleate and the platinum additive was platinum COD.

When DOC was removed, the particulate reduction efficacy was slightly reduced to 57%, but NO was present₂Only 25% of the total nitrogen oxide species. After another 25 hours of operation on treated fuel, particulates and NO₂Are all further unexpectedly reduced.

One unexpected positive result found in the tests was particulate emissions and NO when FBC was added to baseline No.2d or ULSD without any post-treatment equipment being placed₂The percentage is reduced. For No.2D, the particulate was reduced by 15% from 0.253 to 0.215 on the treated fuel (0.15/7.5 ppm Pt/Ce), and NO was₂From 17% to 13%. For ULSD, with FBC addition (0.5/7.5 ppm Pt/Ce) to the fuel, the particulates dropped from 0.244 to 0.207 with NO₂The reduction from 18% to 12% is 15%. Thus, there are benefits to using FBCs alone or with catalytic after-treatment devices to reduce particulate and other emissions. Highly catalyzed DOCs, as they produce NO in the prior art₂Advocated as an important aid in particulate reduction, here it appears that not more effective than the correct FBC for particulate reduction, but can adversely affect NO₂And (5) discharging. This is not disclosed in the prior art.

Comparison of emissions from 1990 International 7.6 liter DTA-466 Engine

(average of three warm Start tests)

Amount of contaminants (g/hp-hr)

Example 4

An engine dynamometer test was performed on a Cummins 275 horsepower 8.3 liter diesel engine certified to meet 1991 California and US Environmental Protection Agency joint Emission standards (California and US Environmental Protection Agency). The test cycle is in accordance with the EPA transient test protocol of the united states test protocol (FTP).

The transient test cycle is described by way of a percentage of maximum torque and a percentage of rated speed for each 1 second interval over the test cycle during 1199 seconds. The first five minutes of the test cycle was designated as the New York Non-freeway (nynf) portion of the test and represents operation in cities with significant idle time. The second five minutes is called the Los Angeles off Highway Freeway (LANF) section. This part of the test also represents operation in the city, but without a significant amount of idle time. The third five minute segment of the test is called the Los Angeles Highway (LAF) section. This represents operation in a highway. The last five minutes is a repeat of the NYNF moiety.

These four fractions produced a 20 minute transient cycle of EPA. The results represent the average of three "hot start" replicates for each fuel.

The results are graphically represented as a reduction in Hydrocarbon (HC), carbon monoxide (CO), oxides of nitrogen (NOx) and Particulate (PM) emissions for each test fuel relative to the emissions in a standard No.2 highway reference fuel containing 386ppm sulfur.

In FIG. 1, the addition of bimetallic platinum/cerium Fuel Borne Catalyst (FBC) to the fuel at concentrations of 0.15ppm platinum and 7.5ppm cerium metal produced an 11% particulate reduction (No. 2D + FBC). For comparison, an ultra low sulfur diesel with 9ppm sulfur was run without FBC and produced a particulate reduction of 6% relative to baseline No.2d, as shown in the figure (ULSD). The same ULSD treated with a fuel borne catalyst of 0.5ppm Pt and 7.5 Ce then produced a PM reduction of 13% relative to baseline No.2d or untreated ULSD, with the highest reduction in HC, CO and NOx emissions. These data demonstrate the benefits of engine-out pollutant reduction, including particulate reduction, of FBCs in standard or ultra-low sulfur fuels. The results are summarized in fig. 1.

Example 5

In another test, on a 1990 Cummins model 8.3 liter engine manufactured in accordance with 1991 Combined emissions Standards, with a different baseline from example 4, the engine was operated on baseline No.2D fuel over three "hot start" 20 minute transient cycles. Emissions are reported in the table below as average grams/horsepower-hour. Particulate emissions were measured at 0.189 gm/hp-hr. Operation on ultra low sulfur diesel fuel (ULSD) produced a smaller reduction in particulate emissions of up to 0.182 micrograms/hp-hr. For each reference fuel, NO₂The emission is kept between 15 and 16 percent of the total nitrogen oxide emission.

Treatment of No.2D with a bimetallic FBC with 0.15ppm platinum and 7.5ppm cerium produced a particle reduction of 13% to 0.164 g/HP-hr with NO₂From 0.8 gr/hp-hr to 0.6 gr/hp-hr. This is in contrast to conventional approaches for particulate reduction that employ heavily catalyzed devices on No.2 fuel to convert NO to NO₂And may also convert sulfur to sulfate particulate emissions. The 13% PM reduction was surprising for low levels of FBC and significant for the smaller PM reduction achieved using ULSD alone.

Further testing showed that the benefits of bimetallic FBC in the ratio of 0.5ppm Pt and 7.5ppm Ce were maintained in ULSD fuels. PM reduction of 12% relative to baseline ULSD while maintaining low NO₂And (5) discharging.

Engine output data for bimetallic FBC on Cummins 8.3L at 1991 certified emissions

(average of three warm Start tests)

Example 6

Similar repeat tests on a 1998 Detroit Diesel 12.7 liter engine are given in FIG. 2 and show a particulate reduction of 11% for FBC in No.2D fuel at a treat rate of 0.5ppm Pt/7.5ppm Ce and a 15% reduction for untreated ULSD fuel. When added to ULSD fuel, FBC increased particulate reduction to 28% relative to baseline on untreated No.2d fuel.

These results again demonstrate the ability of the FBC to reduce engine out emissions including PM when added to No.2d fuel or ULSD fuel. The results are summarized in fig. 2.

Example 7

Testing on a 1990 International Harvister 7.6 liter engine showed a 15% reduction in PM for No.20 fuel treated with FBC at a treat rate of 0.15/7.5 ppm. For comparison, a commercial ULSD without FBC provided a PM reduction of 3%. FBC was added to ULSD at a dose rate of 0.15/7.5ppm, with 18% reduction in particulates; with low aromatic ULSD, FBC produced a particle reduction of 29%. The results are summarized in fig. 3.

Example 8

A series of tests were conducted on a 1995 Navistar 7.6 liter engine mounted on a transient engine dynamometer. Three thermal test cycles were run for the baseline on No.2D fuel (> 300ppm S) and then for each of the three different FBC additives used in ULSD (< 15ppm S).

Additive A provided 0.15/4/4ppm Pt/Ce/Fe; additive B provided 0.15ppm/7.5ppm Pt/Ce; and additive C provided 0.15/5.6/2.4ppm Pt/Ce/Fe. All additives contained the same commercial detergent package to aid in catalyst stability. For the three additives, in HC, CO, NOx and NO₂Aspects show similar reductions. The particulate reduction for bimetallic additive B was slightly better, 32% relative to baseline No.2D, while both additives a and C provided a PM reduction of 25%. In all cases, the blending of additives with ULSD in NOx and NO₂The aspects all provide unexpectedly good reduction.

In certain applications, the use of trimetallic may present a cost advantage over bimetallic or may be preferred for applications in the regeneration of exhaust after-treatment devices such as DOCs, DPFs, wire mesh filters, or combined systems.

For bimetallic on 1995 Navistar DT 4667.6 lift engine

And engine output data for trimetallic additives

(average of three warm Start test results, g/hp-hr)

Note: Pt/Ce with A of 0.15/4/4

Pt/Ce with B of 0.15/7.5

Pt/Ce with C of 0.15/5.6/2.4

The previous description is provided to enable any person skilled in the art to practice the present invention. It is not intended to detail all of the possible modifications and variations that will become apparent to the skilled worker upon reading the description. It is intended, however, that all such modifications and variations be included within the scope of the invention that is seen in the foregoing description and which is otherwise defined by the following claims. The claims are intended to cover the indicated components and steps in any arrangement and combination which is effective to meet the objectives intended for the invention, unless the context specifically indicates the contrary.

Claims (1)

1. A method for combusting carbonaceous fuel, comprising: mixing fuel or combustion air with a multi-component combustion catalyst comprising a platinum composition and an iron composition, the level being reduced to between 0.0005ppm and 2.0ppm for platinum and between 0.5ppm and 10ppm for iron, wherein the ratio of iron to platinum is between 75: 1 and 10: 1; and combusting diesel fuel having a sulfur content of no more than 0.0015 wt% and an aromatics content of 1-8 vol% with air in the presence of the multi-component catalyst.