Fuel and related compositions – Liquid fuels – Silicon containing
Reexamination Certificate
1999-10-15
2001-03-13
Medley, Margaret (Department: 1714)
Fuel and related compositions
Liquid fuels
Silicon containing
C044S443000
Reexamination Certificate
active
06200359
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to fuel oil compositions, processes for their preparation and their use in fuelling road vehicles.
A common problem in the handling of liquid fuels, particularly fuel oil compositions, e.g. in the processing and transport of such fuels, but particularly in the fuelling of road vehicles, is foaming of the fuel.
A broad class of organosilicone antifoam additives for liquid hydrocarbon fuels, particularly fuel oils, has been developed, for example those commercially available under the “TEGOPREN” trade mark ex Th. Goldschmidt A. G. (e.g. “T 5851” and “MR 2068”), Q25907 (ex Dow Corning), under the “RHODORSIL” trade mark ex Rhone Poulenc, or under the “SAG” trade mark ex OSi Specialties (e.g. “TP-325” and “Y-14326”).
Organosilicone antifoam additives, which are siloxane-containing compounds, are described, for example in U.S. Pat. No. 4,690,688 (Dow Corning), U.S. Pat. No. 5,542,960 (Osi Specialties), U.S. Pat. No. 5,613,988 (Th. Goldschmidt) and EP-A-849 352 (Th. Goldschmidt).
Dehazers are frequently incorporated into fuel oil compositions. Dehazers are typically polyoxyalkylene glycol derivatives, and polyoxyalkylene glycol dehazers include formaldehyde resins, which can be regarded as polyoxymethylene glycol derivatives, e.g. alkoxylated phenol formaldehyde polymer dehazers. Commercial examples of polyoxyalkylene glycol dehazers include dehazers available ex Nalco/Exxon Energy Chemicals Ltd and dehazers available under the “TOLAD” trade mark ex Petrolite Ltd.
DESCRIPTION OF THE INVENTION
It has now surprisingly been found that subjecting an organosilicone antifoam additive to a heat treatment and subsequently incorporating the resulting additive in a fuel oil composition together with a polyoxyalkylene glycol dehazer can result in enhanced antifoam performance being achieved in the fuel oil composition. Heat treatment of already formed fuel oil compositions, or of additive concentrates containing both organosilicone antifoam additive and polyoxyalkylene glycol dehazer before adding concentrate to fuel oil, has not been found to result in a similar effect.
According to the present invention there is provided a fuel oil composition comprising a major proportion of a liquid hydrocarbon middle distillate fuel oil, from 1 to 100 ppmw based on the composition of a polyoxy-alkylene glycol dehazer and from 1 to 100 ppmw based on the composition of an organosilicone antifoam additive, wherein before mixing of the organosilicone antifoam with any other component of the fuel oil composition, the organosilicone antifoam additive is heated at a temperature of at least 40° C. for a sufficient period of time to achieve improved antifoam properties of the fuel oil composition.
The organosilicone antifoam additive is preferably heated at a temperature in the range 40° C. to 80° C., preferably 40° C. to 65° C., more preferably 40° C. to 60° C.
The duration of the heat treatment will vary according to the temperature of the heat treatment and the specific organosilicone antifoam additive selected, and optimal combinations can readily be found by routine testing, as will be apparent in the examples given hereinafter.
The organosilicone antifoam additives are siloxane-containing compounds, and examples thereof are described, for examples, in U.S. Pat. Nos. 4,690,688 (Dow Corning), 5,542,960 (Osi Specialties) and 5,613,988 (Th. Goldschmidt) and EP-A-849 352 (Th. Goldschmidt). Commercially available examples are those available from Th Goldschmidt A. G. under the trade mark “TEGOPREN” (e.g. “T 5851” and “MR 2068”), from Dow Corning under the trade designation “Q25907”, from Rhone Poulenc under the trade mark “RHODORSIL”, and from Osi Specialties under the trade mark “SAG” (e.g. “TP-325” and “Y-14326”).
The polyoxyalkylene glycol dehazer may consist of a single polyoxyalkylene glycol derivative, or it may contain more than one such derivative, and optionally an additional component or components which are not polyoxyalkylene glycol derivatives may be present. Polyoxyalkylene glycol dehazers include formaldehyde resins, which can be regarded as polyoxymethylene glycol derivatives, e.g. alkoxylated phenol formaldehyde polymer dehazers. Commercially such dehazers are available, for example, from Nalco/Exxon Energy Chemicals Ltd, e.g. the alkoxylated phenol formaldehyde polymer dehazers designated “EC5541A”, “EC7115A” and “EC5642A”, and from Petrolite Ltd under the “TOLAD” trade mark, e.g. the polyoxyalkylene dehazers designated “TOLAD 9318” and “TOLAD 9312”.
The liquid hydrocarbon middle distillate fuel oil is derived from petroleum and will typically have a boiling range in the range 100° C. to 500° C., e.g. 150° C. to 400° C. Such petroleum-derived fuel oils may comprise atmospheric distillate or vacuum distillate, or cracked gas oil or a blend in any proportion of straight run and thermally and/or catalytically cracked distillates. Preferred fuel oil compositions of the invention are diesel fuel compositions. Diesel fuels typically have initial distillation temperature about 160° C. and final distillation temperature of 290-360° C., depending on fuel grade and use.
The fuel oil itself may be an additised (additive-containing) oil or an unadditised (additive-free) oil. If the fuel oil is an additised oil, it will contain minor amounts of one or more additives, e.g. one or more additives selected from anti-static agents, pipeline drag reducers, flow improvers (e.g. ethylene/vinyl acetate copolymers or acrylate/maleic anhydride copolymers) and wax anti-settling agents (e.g. those commercially available under the Trade Marks “PARAFLOW” (e.g. “PARAFLOW” 450; ex Paramins), “OCTEL” (e.g. “OCTEL” W 5000; ex Octel) and “DODIFLOW” (e.g. DODIFLOW” v 3958; ex Hoechst).
The fuel oil preferably has a sulphur content of at most 0.05% by weight (500 ppmw) (“ppmw” is parts per million by weight). Advantageous compositions of the invention are also attained when the sulphur content of the fuel oil is below 0.005% by weight (50 ppmw) or even below 0.001% by weight (10 ppmw).
The organosilicone antifoam additive and the polyoxyalkylene glycol dehazer may conveniently each be present in amounts up to 50 ppmw based on the fuel oil composition. The concentration of the polyoxyalkylene glycol dehazer is preferably in the range 1 to 20 ppmw, and more preferably 2 to 10 ppmw (e.g. about 5 ppmw). The concentration of the organosilicone antifoam additive is preferably in the range 1 to 20 ppmw, and more preferably 2 to 10 ppmw (e.g. about 5 ppmw). The relative concentrations organosilicone antifoam additive:polyoxyalkylene glycol dehazer are preferably in the range 1:10 to 10:1, more preferably 1:5 to 5:1, advantageously 2:5 to 5:2 and conveniently about 1:1.
Fuel oil compositions of the present invention may contain other additive components in addition to those already indicated. For example, a dispersant additive, e.g. a polyolefin substituted succinimide or succinamide of a polyamine, may be included. Such dispersant additives are described for example in UK Patent 960,493, EP-A-147 240, EP-A-482 253, EP-A-613 938, EP-A-557 561 and WO 9842808. Such dispersant additives are preferably present in amounts in the range of from 10 to 400 ppmw, more preferably 40 to 200 ppmw, active matter based on the fuel oil composition.
When the liquid hydrocarbon middle distillate fuel oil has a sulphur content of 500 ppmw or less, the fuel oil composition preferably additionally contains a lubricity enhancer in an amount in the range from 50 to 500 ppmw based on the fuel oil composition. Commercially available lubricity enhancers include those available as “EC 831” and “PARADYNE (trade mark) 655” ex Exxon Chemical Ltd, “HITEC” (trade mark) E 580 ex Ethyl Corporation and “VECTRON” (trade mark) 6010 ex Shell Additives International Ltd.
Further additional additive components which may be present include ignition improvers (cetane improvers) (e.g. 2-ethylhexyl nitrate, cyclohexyl nitrate, ditertiarybutyl peroxide and those disclosed in U.S. Pat. No. 4,208,190 (at Column 2, line 27 to Column 3, line
Grundy Michael John
Redford Andrea
Medley Margaret
Shell Oil Company
Toomer Cephia D.
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