JP2002060765A - Fuel oil additive for diesel engine with diesel particulate removal device and fuel oil containing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the combustibility of PM collected by a filter of a DPF, to stably burn the PM at a low temperature, to enhance the removal efficiency, and to prolong the life of the DPF. Provided is a fuel oil additive for a diesel engine with a DPF, and a fuel oil containing the additive. The DPF comprises a molybdenum compound and has a DPF.
A fuel oil additive for a diesel engine with a DPF having a function of improving the combustibility of PM collected by the filter described above, and a fuel oil containing the additive.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a fuel oil additive for a diesel engine equipped with a diesel particulate filter (Diesel Particulate Filter, hereinafter abbreviated as "DPF") and a fuel oil containing the same. , Particulate matter collected by a DPF filter (particulate matter, hereinafter abbreviated as “PM”)
A fuel oil additive for a diesel engine with a DPF, which is capable of improving the combustibility of PM, stably burning the PM at a low temperature, increasing the removal efficiency thereof, and extending the life of the DPF, and The present invention relates to a fuel oil containing:

[0002]

2. Description of the Related Art Diesel engine vehicles have better fuel efficiency than gasoline engine vehicles, are effective in reducing carbon dioxide, and have the advantage that light oil used as fuel oil is lower in cost than gasoline. is there. However, PM contained in the combustion gas discharged from diesel vehicles has recently been widely considered due to the problem of environmental pollution. This PM is a fine burnt of fuel oil such as soot, and is known to have an adverse effect on the respiratory system when it enters the human body. Therefore, reduction of PM in exhaust gas is the biggest issue for diesel vehicles. Therefore, in Japan, new regulations aimed at achieving in 2005 require manufacturers to reduce PM emissions to one-third of the current regulations.
We are considering obligating diesel vehicles running in Tokyo to have a DPF by around 2003, and it is highly likely that they will spread to other local governments.

[0003] Under these circumstances, efficient and practical DPFs are being actively developed. Currently, several types of DPFs, specifically (1) an alternate regeneration DPF,
(2) Continuous regeneration type DPF by NO ₂ oxidation method, (3)
A continuous regeneration type DPF using a catalytic oxidation method and (4) an intermittent regeneration type DPF have been proposed. The alternate regeneration type DPF of the above (1) is a switching type that alternately performs collection and regeneration by using two filter units in which both sides of a silicon carbide fiber nonwoven fabric are sandwiched between a wire mesh heater and a protective wire mesh. This DPF can handle the current diesel oil with a high sulfur content, but requires a large current to burn PM.
In addition to the necessity of mounting a dedicated large-capacity generator, there is a problem that the filter may be damaged by rapid combustion.

[0004] (2) The continuous regeneration type DPF using the NO ₂ oxidation method uses a porous ceramic made of cordierite having a wall flow honeycomb structure as a filter.
By the oxidation catalyst provided on the upstream side, to oxidize NOx to NO _2, by using a strong oxidizing power of this NO _2, a continuous regeneration type apparatus for burning PM collected in the filter at low temperatures. However, in this method, the activity of the oxidation catalyst is degraded due to the sulfur content in the exhaust gas, and the function of the oxidation catalyst is not sufficiently exhibited. Therefore, it is necessary to reduce the sulfur content in the fuel oil. There is a problem that it is difficult.
The continuous regeneration type DPF of the catalytic oxidation method (3) uses a porous ceramic filter made of cordierite having a wall-flow honeycomb structure coated with two kinds of metal catalysts, and does not require a heating device such as a heater. P collected by the filter only by the action of
This is a continuous regeneration type device for burning M. In this scheme,
The metal catalyst is relatively insensitive to the sulfur content in the exhaust gas, and thus can be applied to existing diesel oil. However, the metal catalyst is more susceptible to phosphorus, and the lower the sulfur content, the higher the performance. Furthermore, since it is necessary to drive the exhaust gas at a temperature of about 300 ° C. or more at a certain comparative ratio or more, it is difficult to apply the method to a vehicle or a passenger car traveling at a low speed for a long time. (4) The intermittent regeneration type DPF uses a porous ceramic filter made of silicon carbide having a wall flow honeycomb structure, captures PM, injects fuel at the time of regeneration, raises the temperature of exhaust gas, and generates hydrocarbons using an oxidation catalyst. This is a method of oxidizing carbon monoxide and further raising the temperature to burn PM. In this method, a cerium compound is added to fuel oil, and P
Reduce the amount of M generated. This method is applicable to current diesel oil, but requires power supply equipment for regeneration.
After the combustion of M, cerium oxide remains and deposits on the filter,
There is a problem of shortening the life of the DPF.

As described above, the D which is currently being developed is
PF has both advantages and disadvantages, and is not always satisfactory. Industrially, it is important to effectively exert the function of the DPF and to prolong its service life. To this end, it is necessary to reduce the amount of emitted PM,
It is important to burn PM at as low a temperature as possible.
As a method of reducing the amount of emitted PM and lowering the combustion temperature of PM, for example, a cerium compound is added to fuel oil to lower the combustion temperature of PM, as in the above-mentioned (4) intermittent regeneration type DPF. A method and a method of adding an alkaline earth metal salt or an iron compound to fuel oil to reduce the emission amount of PM are known. However, although the above method of adding a cerium compound reduces PM by adding a relatively large amount, the cerium compound remains after combustion and accumulates on a filter, which rather shortens the life of the DPF. Further, in the method of adding an alkaline earth metal salt or an iron compound, similarly to the above, combustion residues are deposited on the filter, and the life of the DPF is reduced.

[0006]

SUMMARY OF THE INVENTION The present invention can improve the combustibility of PM collected by a filter of a DPF under such circumstances, and stably burn the PM at a low temperature. It is an object of the present invention to provide a fuel oil additive for a diesel engine with a DPF, which can enhance the removal efficiency and extend the life of the DPF, and a fuel oil containing the same.

[0007]

The present inventors have conducted intensive studies to develop a fuel oil additive for a diesel engine with a DPF having the above-mentioned preferable properties, and as a result, the molybdenum compound was added to the fuel oil for a diesel engine. It has been found that by adding a small amount, the combustibility of PM is improved. The present invention has been completed based on such findings. That is, the present invention comprises a molybdenum compound,
Further, the present invention provides a fuel oil additive for a diesel engine with a DPF, which has a function of improving the combustibility of PM collected by a DPF filter.
The present invention also provides a fuel oil obtained by blending the above additive with the fuel oil.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The fuel oil additive for diesel engines with PDF of the present invention (hereinafter sometimes abbreviated as "fuel oil additive of the present invention") is a PM filter collected by a DPF filter. Of the P at low temperatures
It is for burning M, and in the present invention,
Molybdenum compounds are used. The molybdenum compound is not particularly limited as long as it can be dispersed or dissolved in a diesel engine fuel oil, and can be appropriately selected from various molybdenum compounds and used. An oil-soluble substance is preferred. Examples of the oil-soluble molybdenum compound include organic acid molybdenum salts such as molybdenum alkyl phosphate and molybdenum carboxylate, and molybdenum thiophosphate and thiocarbamate. They are,
It may be added to the fuel oil as it is, or may be dissolved in a suitable organic solvent and added to the fuel oil in the form of a solution. When molybdenum thiophosphate or thiolbamate is used, it is added so that the total sulfur content in the fuel oil is equal to or less than the standard value in the fuel oil for diesel engines. In particular, those which become MoO ₃ or phosphomolybdic acid as the combustion residue are preferable. These molybdenum compounds may be used alone or in a combination of two or more. The addition amount is selected so that the content of molybdenum in the fuel oil is preferably 100 ppm or less. Molybdenum content is 100p
If it exceeds pm, it causes corrosion in the flue, and the amount of PM residue remaining on the filter increases, which may shorten the life of the DPF.

[0009] Since these molybdenum compounds are contained in the exhaust gas as molybdenum oxide or a composite oxide of molybdenum and other elements, they are collected by a DPF filter and mixed into PM. The flammability of the PM is improved, and the combustion temperature is lowered by about 40 to 50 ° C. This effect is stably exhibited without being affected by other components in the exhaust gas, for example, a sulfur compound or a phosphorus compound.
The fuel oil for a diesel engine to which the fuel oil additive of the present invention is applied is not particularly limited, and a fuel oil conventionally used for diesel engines, for example, a base oil mainly composed of light oil, has a low-temperature fluidity. Improver, lubricity improver,
Examples of such additives include various additives commonly used in fuel oils such as a cetane number improver and a detergent, if necessary.

[0010]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Examples Carbon black [PM manufactured by Mitsubishi Chemical Corporation "MA"
100 "), and the molybdenum compound powder shown in Table 1 as a combustion residue was mixed at a ratio of 10 parts by weight to 100 parts by weight, and the combustion temperature of the mixture was set to DT-TG.
A (differential thermal-thermogravimetric analysis) was used to measure the temperature in air at a rate of 10 ° C./min. The results are shown in Table 1. COMPARATIVE EXAMPLE As the combustion residue, powders of various metal compounds shown in Table 1 were used, and the same as in the example. The combustion temperature of only carbon black was measured in the same manner as in the example. Table 1 shows the results.

[0011]

[Table 1]

As is clear from Table 1, the presence of the molybdenum compound lowers the combustion temperature of PM specifically.

[0013]

The fuel oil additive of the present invention, when added to a diesel engine fuel oil in a small amount, reduces the flammability of PM collected by the DPF filter to other components in the exhaust gas, such as sulfur. The PM can be improved without being affected by compounds and phosphorus compounds, and the PM can be stably burned at a low temperature.
Life can be extended. In addition, since only a very small amount of residual combustion remains on the filter,
Substantially does not hinder the life extension.

Claims (4)

[Claims] 1. A fuel oil addition for a diesel engine with a diesel particulate removal device, comprising a molybdenum compound and having a function of improving the combustibility of particulate matter collected by a filter of the diesel particulate removal device. Agent. 2. The fuel oil additive according to claim 1, wherein the molybdenum compound is oil-soluble. 3. The fuel oil contains 100 p as molybdenum.
The fuel oil additive according to claim 1 or 2, which is contained at a ratio of not more than pm. 4. A fuel oil obtained by blending the additive according to claim 1 with the fuel oil.