Chemistry of hydrocarbon compounds – Product blend – e.g. – composition – etc. – or blending process... – For fuel use only
Reexamination Certificate
1999-12-10
2001-04-10
Howard, Jacqueline V. (Department: 1764)
Chemistry of hydrocarbon compounds
Product blend, e.g., composition, etc., or blending process...
For fuel use only
C044S300000, C208S015000
Reexamination Certificate
active
06215034
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a novel diesel fuel oil composition, more particularly a base fuel oil for diesel fuel oil to exhibit excellent lubricity improving effect, which is incorporated with a lubricity improver.
DESCRIPTION OF THE RELATED ART
Diesel engines are widely used for various purposes, e.g., for driving automobiles, ships and construction machines, and are still spreading further. As a result, fuel oil for diesel engines is increasingly in demand, and becoming heavier to satisfy the increased demands, because straight-run diesel fuel oil is distilled deeper and/or blended with heavier fractions. It is anticipated that the above trends are accompanied by increased NOx and particulate matter emissions in exhaust gases to further aggravate air pollution.
A variety of techniques have been proposed from wide angles to abate air pollutants, e.g., NOx and particulate matter, present in exhaust gases from diesel engines, such as improved combustion chamber shapes, installation of various devices (e.g., exhaust gas recycle (EGR) system, exhaust gas cleaning-up catalytic converter system and particulate matter trapping system), and improvement of diesel fuel and lubricant oils. An EGR system, which is considered to be one of the effective means to abate the pollutant emissions, recycles part of exhaust gases from the diesel engine back to the combustion chamber as part of the combustion air. However, it may cause several problems when sulfate ions and particulate matter are present in the exhaust gases, such as deteriorated durability and reliability of the engine, deteriorated lubricant oil, increased emissions of particulate matter and decreased power output. These problems will be further aggravated when it is installed in a direct-injection engine, which is required to operate at a high load. The sulfate ions are derived from sulfur compounds present in diesel fuel oil, and “low-sulfur diesel fuel oil” containing sulfur at 0.05 wt % or less has become a social need.
Sulfur in a diesel fuel oil can be reduced by refining, in particular catalytic hydrotreating, of the base stocks. This, however, is accompanied by decreased lubricity of diesel fuel oil itself, and will damage the injection device of the engine. It is known that wear of the injection pump notably increases as sulfur content decreases from 0.2 wt %.
Attempts have been made to improve diesel fuel oil lubricity by the aid of lubricity improver to solve the above problems, but failed to produce satisfactory results.
DESCRIPTION OF THE INVENTION
The present invention relates to a base fuel oil for diesel fuel oil having properties necessary for a lubricity improver to exhibit its lubricity-improving effect, and a diesel fuel oil comprising the above base fuel oil incorporated with a lubricity improver.
The present invention is based on the discovery that the lubricity improver, that lubricity of diesel fuel oil is improved as a lubricity improver in the base fuel oil is quickly adsorbed on the metal surface and that the base fuel oil must have low affinity for the lubricity improver not to hinder adsorption of the improver on the metal surface.
The present invention provides a base fuel oil for diesel fuel oil of improved response to lubricity additives characterized by (1) sulfur content of 0.03 wt % or less, (2) nitrogen content of 35 wt. ppm or less, (3) density of 0.835 g/cm
3
or less and (4) solubility parameter of 7.00 to 8.10.
The present invention also provides a diesel fuel oil composition comprising the above base fuel oil which is incorporated with a lubricity improver.
The present invention, relating to the above base fuel oil for diesel fuel oil and diesel fuel oil composition, includes the following preferred embodiments:
(1) the above mentioned base fuel oil for diesel fuel oil composition having a density of 0.830 g/cm
3
or less,
(2) the base fuel oil for diesel fuel oil composition of the above (1) having a solubility parameter of 7.50 to 8.05, and
(3) the above mentioned diesel fuel oil composition comprising the base fuel oil of one of the above (1) and (2) which is incorporated with a lubricity improver.
The present invention is described below in further detail. The base fuel oil of the present invention for diesel fuel oil has a sulfur content, nitrogen content, density and solubility parameter in specific ranges. The diesel fuel oil composition of the present invention comprises the above base fuel oil which is incorporated with a lubricity improver.
Base Fuel Oil for Diesel Fuel Oil
The base fuel oil of the present invention for diesel fuel oil has a sulfur content of 0.03 wt % or less, preferably 0.025 wt % or less, and nitrogen content of 35 wt. ppm or less, preferably 25 wt. ppm or less. When its sulfur content exceeds 0.03 wt % or nitrogen content exceeds 35 wt. ppm, the base fuel oil will have sufficient affinity for the lubricity improver with a polar group to prevent it from being adsorbed on the metal surface. As a result, the lubricity improver incorporated in the base fuel oil will no longer fully exhibit its intended lubricity improving effect.
The base fuel oil of the present invention for diesel fuel oil also has a density of 0.835 g/cm
3
or less, preferably 0.830 g/cm
3
or less. When its density exceeds 0.835 g/cm
3
, difference in density between the base fuel oil and lubricity improver will be sufficiently small to prevent the latter from being adsorbed on the metal surface. As a result, the lubricity improver incorporated in the base fuel oil will no longer fully exhibit its intended lubricity improving effect.
The base fuel oil of the present invention for diesel fuel oil also has a solubility parameter of 7.00 to 8.10, preferably 7.50 to 8.05. When its solubility parameter is below 7.00, the base fuel oil will be insufficiently compatible with the lubricity improver, possibly causing phase separation. When its solubility parameter exceeds 8.10, difference in solubility parameter between the base fuel oil and lubricity improver will be sufficiently small to excessively increase compatibility between them, possibly preventing the lubricity improver incorporated in the base fuel oil from fully exhibiting its intended lubricity improving effect.
Solubility parameter is a measure of solubility in a nonelectrolytic solvent, and a solute will be more compatible with a solvent when difference between them in solubility parameter decreases. It is given by surface tensions of solvent and solute:
&dgr;=4.19
P
0.43
P=&sgr;V
−⅓
wherein, &dgr; stands for solubility parameter, P for internal pressure (dyn/cm
2
), &sgr; for surface tension (dyn/cm) and V for molar volume (cm
3
).
A lubricity improver can fully exhibit its intended effect when the base fuel oil in which it is incorporated has the following properties: (1) sulfur content of 0.03 wt % or less, (2) nitrogen content of 35 wt. ppm or less, (3) density of 0.835 g/cm
3
or less and (4) solubility parameter of 7.00 to 8.10.
The above properties can be adjusted by various methods, e.g., blending of petroleum fractions from different crude sources, solvent extraction, hydrotreatment and adequate combination thereof. These fractions are used individually or in combination for the base fuel oil of the present invention.
Diesel Fuel Oil Composition
The diesel fuel oil composition of the present invention comprises the above base fuel oil which is incorporated with a lubricity improver and other types of additives.
The lubricity improver useful for the present invention is not limited, and can be selected from the known ones. These include fatty acids, e.g., stearic, linolic and oleic acid, and esters, e.g., those of the above fatty acids and poly-alcohols, represented by the ester of linolic acid and glycerin. The preferable one is an ester. A lubricity improver dosage below 0.002 wt % may not satisfactorily improve lubricity, and above 0.1 wt % is not economical, because lubricity will not be improved as much as increased dosage. The preferable lubricity improver dosage is 0.005
Murakami Kazuyuki
Namiyama Kazuyoshi
Oomori Noriaki
Allocca Joseph J.
Howard Jacqueline V.
Tonen Corporation
LandOfFree
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