Mineral oils: processes and products – Products and compositions – Fuels
Reexamination Certificate
1999-07-09
2001-02-13
Howard, Jacqueline V. (Department: 1764)
Mineral oils: processes and products
Products and compositions
Fuels
C208S017000, C585S014000
Reexamination Certificate
active
06187171
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an unleaded, high-octane gasoline composition, more particularly an unleaded, high-octane gasoline composition which forms little gums, and shows excellent effects of cleaning an air-intake system and combustion chamber of a gasoline engine.
BACKGROUND OF THE INVENTION
High-octane gasoline blending stocks produced by Fluid Catalytic Cracking (FCC) units and catalytic reformers have been more extensively used for automobile gasoline, since introduction of regulations on use of lead compounds, e.g., tetraethyl lead, as octane improvers. Furthermore, improvement of automobile mileage is increasingly socially required, which calls for higher engine compression ratio and hence higher-octane unleaded gasoline.
Such high-octane, unleaded gasoline contains large proportions of high-octane gasoline component stocks, e.g., those produced by FCC units and reformers, and toluene. For example, Japanese Patent Publication No. 3-21593 discloses unleaded, high-octane gasoline composed of reformate as the heavier fraction and FCC naphtha as the lighter fraction to have a research octane number of 96 or more. Japanese Patent Publication No. 7-10981 discloses unleaded, high-octane gasoline containing, as the essential components, reformate of specific properties, alkylate and isopentane, to have a research octane number of 99.5 or more. Octane number of reformate has been increased by increasing severity (high temperature operation) of reformers, fractionating reformate to extract higher-octane fraction and such like.
It is noted, however, that unleaded, high-octane gasoline causes several problems while it is stored or in service, such as accelerated formation of gums to clog devices associated with tank, and fuel systems (in particular, fuel filters) in the engine. The more functional gasoline engine is more sensitive to the effects of deposits in the air-intake system on engine performance. For example, the electronically controlled fuel injection device precisely controls air/fuel ratio to improve engine performance, and to improve mileage and exhaust gas composition. However, air/fuel ratio will be no longer adequately controlled when deposits are formed on the air-intake valve, because they will work as obstacles to flow of gasoline ejected out of the fuel injection device, with the result that its operability is lowered. Deposits formed on the combustion chamber walls, on the other hand, tend to increase octane requirements. Therefore, there have been strong requirements to control formation of deposits, both in air-intake system and combustion chamber.
A number of techniques have been proposed to reduce gums in gasoline. For example, Japanese Laid-open Patent Application No. 10-77486 discloses gasoline incorporated with an aliphatic nitroxide compound to control formation of gums. Japanese Laid-open Patent Application No. 9-95688 discloses gasoline aimed at improvement of cleanliness in an air-intake valve and port in a gasoline engine, claiming that formation of deposits on combustion chamber walls can be controlled when gasoline has an octane number of 98 or more, 50% distillation point of 75° C. to 95° C., 97% distillation point of 155° C. or less, aromatic hydrocarbon content of 35 vol % or less, and content of 10 vol % or less for aromatic hydrocarbons having a carbon number of 8 or more. Japanese Laid-open Patent Application No. 9-286992 discloses that an unleaded gasoline composition shows excellent effects of cleaning an air-intake system and combustion chamber, when it is incorporated with a polyetheramine-based detergent at 70 ppm or more and satisfies a specific relationship involving aromatic hydrocarbon content and distillation temperature.
However, none of these techniques shows sufficient effects of controlling formation of gums, or improving cleanliness in air-intake system or combustion chamber. In particular, the technique which depends on use of an additive tends to increase gasoline production cost.
It is an object of the present invention to provide an unleaded, high-octane gasoline composition which forms little gums, and shows excellent effects of cleaning an air-intake system and combustion chamber of a gasoline engine.
DESCRIPTION OF THE INVENTION
It has been found that heavy aromatic hydrocarbons present in gasoline have an effect on gum formation, and cleanliness of an air-intake system and combustion chamber of a gasoline engine, that there is a correlation between content of aromatic hydrocarbons having a carbon number of 11 or more and formation of gums or cleanliness of air-intake system and combustion chamber, and that the extent of the effects of the aromatic hydrocarbons having a carbon number of 11 or more vary depending on reformer type by which they are produced.
The present invention is an unleaded, high-octane gasoline composition containing (A) at least one reformate fraction produced by a continues regeneration type reformer and/or (B) at least one reformate fraction produced by a fixed-bed type reformer, and satisfies the following conditions (1) to (3):
(1)
Z
=({fraction (1/100)})[&Sgr;(
ax
)+({fraction (1/9)})&Sgr;(
by
)]<0.010
wherein, &Sgr;(ax) is a summation of (ax), wherein (a) is content (vol %) by volume of a fraction falling into the reformate fraction A, (x) is content (vol %) by volume of aromatic hydrocarbons having a carbon number of 11 or more in the fraction (a), and &Sgr;(by) is a summation of (by), wherein (b) is content (vol %) by volume of a fraction falling into the reformate fraction B, (y) is content (vol %) by volume of aromatic hydrocarbons having a carbon number of 11 or more in the fraction (b).
(2) content of aromatic hydrocarbons having a carbon number of 7 to 8 being 30 vol % or more, and
(3) research octane number being 96.0 or more.
At least one reformate fraction (A) means reformate produced by a continuous regeneration type reformer or such reformate treated by fractionation, and at least one reformate fraction (B) means reformate produced by a fixed-bed type reformer or such reformate treated by fractionation.
The present invention relates, as described above, to an unleaded, high-octane gasoline composition, which includes the following as one of the preferred embodiments:
(1) An unleaded, high-octane gasoline composition with Z in the above formula being less than 0.005.
DETAILED DESCRIPTION OF THE INVENTION
(A) Reformate Fraction
The reformate fraction useful for the present invention may be produced by the reforming reactions, involving, e.g., isomerization, dehydrogenation, cyclization and hydrocracking, of heavy naphtha boiling at around 40° C. to 230° C. under elevated temperature and pressure over a reforming catalyst in a flow of hydrogen. The reforming catalysts useful for the present invention include a platinum-based one or bimetallic one with platinum combined with another metal, e.g., rhenium, iridium or germanium. The normal reaction conditions are 450° C. to 540° C. and 7 to 50 kg/cm
2
as reaction temperature and pressure.
The present invention contains one or more specific types of reformate produced from a heavy naphtha fraction by a reformer, namely (A) at least one reformate fraction produced by a continuous regeneration type reformer and/or (B) at least one reformate fraction produced by a fixed-bed type reformer. The reformate fraction (A) may be as-received one produced by a continuous regeneration type reformer or such reformate treated by fractionation, and the reformate fraction (B) may be as-received one produced by a fixed-bed type reformer or such reformate treated by fractionation.
A continuous regeneration type reformer uses a moving bed type reactor, the catalyst being continuously withdrawn therefrom and recycled back thereto after being regenerated by a regenerator. It is characterized by continuous operation (i.e., it is not necessary to stop the operation for catalyst regeneration), and catalyst continuously keeping high activity to give reformate in high yield during the service period. A fixed-b
Allocca Joseph J.
Howard Jacqueline V.
Tonen Corporation
LandOfFree
Unleaded high-octane gasoline composition does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Unleaded high-octane gasoline composition, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Unleaded high-octane gasoline composition will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2595026