Classifications

• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
  • C10L1/00—Liquid carbonaceous fuels
  • C10L1/10—Liquid carbonaceous fuels containing additives
  • C10L1/14—Organic compounds
  • C10L1/18—Organic compounds containing oxygen
  • C10L1/1811—Organic compounds containing oxygen peroxides; ozonides
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
  • F02B3/00—Engines characterised by air compression and subsequent fuel addition
  • F02B3/06—Engines characterised by air compression and subsequent fuel addition with compression ignition
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
  • F02B47/00—Methods of operating engines involving adding non-fuel substances or anti-knock agents to combustion air, fuel, or fuel-air mixtures of engines

Definitions

• This invention relates to a cetane number improver additive for diesel engine fuels, a diesel engine fuel composition containing the additive, and a process for the production of a diesel engine fuel having a high cetane number. Furthermore, it also relates to a technique for utilizing cycle oil obtained by fluidized catalytic cracking of a heavy hydro­carbon oil, tar oil obtained as a by-product by cracking of naphtha, and oil obtained by liquefaction of coal, as diesel engine fuel components.
• diesel engine fuels i.e., gas oil and fuel oil
• gas oil and fuel oil do not have an adequately high cetane number
• diesel knock phenomenon will take place. This may produce loud engine noises and cause a reduc­tion in combustion efficiency. If the cetane number becomes still lower, it may be impossible to start the engine.
• these oils have a very low cetane number of the order of 15 to 25 and contain a considerable amount of polycyclic aromatic compounds (mainly comprising naphthalene and its derivatives), so that it is impossible to mix a high proportion of these oils with other straight-run petroleum oils (i.e., straight-run fractions obtained by distillation of petroleum, such as gas oil and the like).
• cetane number improver additives are nitrate compounds such as tetrahydro-2,5-furan dimethanol nitrate (U.S. Patent 4,522,630), alkyl and alkoxy nitrates (U.S. Patents 4,549,883 and 4,448,587), cyclododecyl nitrate (U.S. Patent 4,420,311), polysaccharide nitrate esters (Japanese Patent Laid-­Open No. 25387/'83) and the like.
• these additives are disadvantageous from an economical point of view, because the desired effect cannot be obtained unless they are added in an amount of as much as 1,000 to 3,000 ppm.
• OLS 3136030 discloses a method in which dialkoxyalkanes are partially oxidized with ozone or H2O2
• U.S. Patent 4,330,304 discloses a combustion improver additive comprising nitroparaffin, cumene hydroperoxide and propylene oxide.
• the present inventors have previously found that the ignitability of a diesel engine fuel can be improved by oxidizing the fuel partially and then feeding it to a diesel engine (Japanese Patent Laid-Open Nos. 45765/'85, 233703/'83 and 24386/'84) and that cumene hydroperoxide can act as a cetane number improver additive (Japanese Patent Laid-Open No. 27767/'85).
• Diesel engines have wide applications including vehicles (such as trucks, buses, passenger cars, locomotives, etc.), construction machinery, electric power generators, ships and the like.
• gas oil and fuel oil are used as fuels.
• the fuels for high-speed and small-sized diesel engines used in trucks, buses and the like have conventionally been produced chiefly from an oil obtained by hydrogenating a petroleum distillate having a boiling range of about 230 to about 400°C.
• the heavy fuels for medium- to large-sized diesel engines used in ships and the like have been produced chiefly from an oil obtained by hydrogenating reduced crude. These fuels have a cetane number of about 45 to about 60 and are suitable for use in diesel engines.
• the present invention has been completed on the basis of the discovery that tetralin hydroperoxide, which is a partial oxidation product of tetralin, is effective in improving the cetane number of diesel engine fuels.
• cetane numbers were measured using a cetane number measuring engine (CFR engine)
• CFR engine cetane number measuring engine
• the present inventors noticed that the performance of tetralin used as the standard fuel varied from lot to lot.
• the tetralin contained a slight amount of tetralin hydroperoxide and its treatment with clay gave a stabilized value. This has led to the discovery that tetralin hydroperoxide can be effectively used as a cetane number improver additive.
• the present inventors have investigated the method of forming tetralin hydroperoxide in a fuel production process and have thereby established a process for the produc­tion of a fuel having a high cetane number from a fuel material having a low cetane number.
• the present invention provides:
• the cetane number improver additive for the present invention comprises, as the active ingredient, tetralin hydroperoxide having a structure represented by the formula
• This compound can be readily formed by exposing tetralin to ultraviolet light in air, or by heating tetralin in an atmosphere of oxygen (preferably in the presence of copper wire).
• an atmosphere of oxygen preferably in the presence of copper wire.
• tetralin when tetralin is placed in an atmosphere of pure oxygen having a gauge pressure of 3 to 10 kg/cm2 and allowed to stand at a temperature of 8 to 100°C for about 6 hours or so, a part of the tetralin is oxidized to form tetralin hydroperoxide in such an amount as to give a peroxide number of about 1,000 to 2,000.
• Peroxide number can be measured according to the procedure described in ASTM D1563-84, "Standard Test Method for Peroxide Number of Mineral Insulating Oils".
• the cetane number improving effect of peroxides is reported in SAE Quarterly Transactions, Vol. 5, No. 3, pp. 404-417 (1951), but no mention of tetralin hydroperoxide is found therein.
• This publication discloses that dibutyl peroxide, when added to a diesel engine fuel in an amount of 1.5% by volume, increases its cetane number by 20.
• the additive of the present invention exhibits a marked effect at considerably lower concentrations, has good storage stability, and is easy to handle. More specifically, the additive of the present invention may be added to a diesel engine fuel in such an amount as to adjust its peroxide number to a value of about 100 to 1,000, thus increasing its cetane number by about 3 to 15.
• the present invention also relates to a process for the production of a diesel engine oil which comprises the steps of hydrogenating a naphthalene- or alkylnaphthalenes-containing hydrocarbon oil to convert at least of the naphthalene or alkylnaphthalenes into tetralin or alkyl derivatives thereof, and partially oxidizing the hydrogenated oil to yield a hydrocarbon oil containing tetralin hydroperoxide.
• the raw oil used in the present invention is a hydrocarbon oil containing a considerable amount of naphthalene or alkylnaphthalenes.
• Specific examples thereof include light cycle oil obtained by fluidized catalytic cracking of a heavy hydrocarbon oil (i.e., FCC-LCO), oil obtained by liquefection of coal, and tar oil obtained as a by-product by cracking of naphtha.
• FCC-LCO useful as a raw oil has a boiling range of about 150 to 350°C and is characterized by n-d-M ring analysis values of 45-65% C A , 0.5-5% C N and 35-50% C p , an aniline point of 20 to 30, and a cetane number of about 10 to 20.
• Useful oil obtained by liquefaction of coal is a gas oil-to-fuel oil A fraction having a boiling range of about 150 to 450°C. This oil is recovered from coal liquefaction equipment and has a cetane number of 15 to 20 and an aromatics content of about 60% by weight.
• Useful tar oil obtained as a by-product by cracking of naphtha is a fraction having a boiling range of about 150 to 400°C and containing a high proportion of aromatics.
• naphthalene or alkylnapthalens having one or more alkyl substi­tuents of 1 to 5 carbon atoms are present in an amount of about 4 to 20% by weight.
• these raw oils are subjected to hydrogenation and partial oxidation under mild conditions.
• the hydrogenation is carried out in the presence of a hydrogenation catalyst commonly used in petroleum refining.
• a hydrogenation catalyst commonly used in petroleum refining.
• catalysts formed by supporting one or more metals (such as Ni, Co, Mo, W, V, Fe and the like) on a suitable carrier (such as alumina, silica, silica-­alumina and the like).
• a catalyst and reaction conditions suitable for partial nuclear hydrogenation of naphthalene and derivatives thereof i.e., suitable for their conversion into tetralin and/or alkyl derivatives thereof.
• W-Ni catalysts are especially preferred for nuclear hydrogenation of naphthalene.
• the hydrogenation conditions can vary according to the types of raw oil and catalyst used, the hydrogenation is usually carried out in the presence of an Ni-W catalyst and under conditions including a reaction pressure (hydrogen pressure) of 40 to 120 kg/cm2, a temperature of 250 to 350°C and preferably 300 to 340°C, an LHSV of 0.4 to 4.0 hr ⁇ 1 and preferably 1.5 to 2.0 hr ⁇ 1, and a hydrogen feed rate of 300 to 1,000 l/l of the raw oil.
• a reaction pressure hydrogen pressure
• a temperature of 250 to 350°C and preferably 300 to 340°C
• an LHSV of 0.4 to 4.0 hr ⁇ 1 and preferably 1.5 to 2.0 hr ⁇ 1
• a hydrogen feed rate 300 to 1,000 l/l of the raw oil.
• the hydrogenation conditions should be selected so that a reaction can take place in which the naphthalene or alkylnaphthalenes present in the raw oil undergo partial nuclear hydrogenation and form tetralin and/or alkyl derivatives thereof.
• the hydrogenation conditions can vary according to the type of catalyst used, they should be selected with due consideration to the criterion that the content of tetralin and/or alkyl derivatives thereof present in the hydrogenated oil should be as high as possible, i.e., not less than 0.5% by weight, preferably not less than 1.0% by weight and more preferably not less than 1.5% by weight.
• the tetralin and/or alkyl derivatives thereof are formed by partial nuclear hydrogenation of the naphthalene or alkylnaphthalenes. Accordingly, no upper limit is placed on the content of such naphthalene compounds in the raw oil, and higher contents are more effective. However, a content of about 3 to about 16% by weight will suffice. In the aforesaid FCC-LCO and oil obtained by liquefaction of coal, such naphthalene compounds are present in an amount of not less than 4% by weight.
• alkyl derivatives of tetralin means derivatives of tetralin having 1 to 3 alkyl substituents each containing 1 to 5 carbon atoms.
• the hydrogenation conditions which cause complete nuclear hydrogenation of the naphthalene or alkylnaphthalenes present in the raw oil i.e., those which convert the naphthalene or alkylnaphthalenes into decalin or derivatives thereof
• the hydrogenation conditions such as type of catalyst, reaction temperature, liquid space velocity and the like, should be selected so that the hydrogenated oil will contain decelin or derivatives thereof in an amount of not greater than 5% by weight, preferably not greater than 3% by weight and more preferably not greater than 1% by weight and, at the same time, will contain tetralin or derivatives thereof in an amount of not less than 0.5% by weight and preferably not less than 1.0% by weight.
• decelin or derivatives thereof in an amount of not greater than 5% by weight, preferably not greater than 3% by weight and more preferably not greater than 1% by weight and, at the same time, will contain tetralin or derivatives thereof in an amount of not less than 0.5% by weight and preferably not less than 1.0% by weight.
• the formation of a large amount of decalin or derivatives thereof causes a decrease in the content of tetralin or derivatives thereof and, therefore, is undesirable for subsequent partial oxidation.
• n-d-M ring analysis values of the hydrogenated oil should be 20-35% C A , 30-45% C N and 30-35% C P , and preferably 25-35% C A and 30-40% C N .
• Oil obtained by liquefaction of coal and tar oil obtained by cracking of naphtha contain a large amount of naphthalene compounds. These oils should likewise be hydrogenated under such conditions that the naphthalene compounds are selectively converted into tetralin or derivatives thereof and their conversion of into decalin or derivatives thereof is suppressed. At the hydrogenation conditions become severer, the hydrogenated oil has a higher cetane number. However, it is desirable that the cetane number of the hydrogenated oil be limited to at most 45 or so.
• the oil obtained by the above-described hydrogenation is then subjected to partial oxidation.
• partial oxidation means a process for increasing the peroxide number of the oil to a value of not less than 100.
• the peroxide number of the oil can be measured according to the procedure described in ASTM D1563-84.
• the partial oxidation may be carried out by placing the oil under an oxygen pressure of 3 to 8 kg/cm2 and allowing it to stand at a temperature of 60 to 100°C for a period of 3 to 10 hours, or by adding a copper of nickel catalyst to the oil and stirring it under milder conditions.
• no particular limitation is placed on the partial oxidation conditions.
• the peroxide number of the oil can be increased to a value of not less than 100, preferably not less than 150 and more preferably not less than 300.
• the oil has a higher cetane number.
• the use of an oil having a high tetralin content provides a peroxide number of not less than 1,500, resulting in a fuel having a high cetane number.
• the tetralin or derivatives thereof present in the oil are readily converted into tetralin hydroperoxide, which functions to markedly improve the cetane number of the oil.
• the partial oxidation may cause the oil to assume a yellow to brown color, but this color may be improved by treatment with clay or the like.
• the tetralin content of the hydro­genated oil may further increased by adding a small amount of tetralin. This serves to further improve the cetane number of the partially oxidized oil. It is to be understood in this connection that, if the hydrogenation is carried out under severe conditions which convert naphthalene into deccalin, subsequent partial oxidation will fail to bring about an improve­ment in cetane number.
• the above-described treatment causes the cetane number of the resulting fuel oil to be increased by 30 to 60, as compared with that of the starting oil.
• FCC-LCO having a cetane number of 14 is used as the starting oil, its hydrogenation and partial oxidation makes it possible to produce a fuel oil having a cetane number of 50 to 75.
• This fuel oil may be used directly as a diesel engine fuel or mixed with other fuel components to yield a diesel engine fuel.
• Light cycle oil obtained by fluidized catalytic cracking of a heavy hydrocarbon oil and having the properties shown in Table 1 was used as the starting oil. According to the following procedure, this starting oil was hydrogenated and then partially oxidized.
• a glass container was placed in a pressure vessel and charged with 50 cc of each of the hydrogenated oils. Then, the pressure vessel was filled with pure oxygen to a pressure of 7.0 kg/cm2, placed in a thermo­static chamber kept at 100°C, and allowed to stand for 8 hours. Thereafter, the pressure vessel was allowed to cool and taken out. In this manner, 100 cc of a partially oxidized oil was obtained from each of the hydrogenated oils. The peroxide number and cetane number of the partially oxidized oil obtained from each of the hydrogenated oils were measured and the results thus obtained are shown in Table 2.
• Cetane number measurements were made in the following manner: 100 cc of each of the partially oxidized oils was mixed with 900 cc of a commercially available gas oil (having a cetane number of 48.4). Using a CFR engine, the cetane number of this mixed oil was measured according to the procedure described in ASTM D613. In Table 2, the measured cetane numbers of the mixed oils are given in the upper row and the estimated cetane numbers of the partially oxidized oils in the lower row.
• a glass container having a capacity of 200 cc was placed in a pressure vessel made of stainless steel. After the glass container was charged with 100 cc of tetralin (reagent grade), oxygen gas was introduced into the pressure vessel until an oxygen pressure of 70 kg/cm2 (G) was reached. Then, the pressure vessel having the glass container placed therein was immersed in a water bath at 100°C and allowed to stand for 6 hours. As a result, a part of the tetralin was partially oxidized to form tetralin hydroperoxide. Thus, a tetralin hydroperoxide-containing tetralin solution having a peroxide number of 1,550 was recovered from the glass container within the pressure vessel.
• tetralin reagent grade
• the cetane numbers of the fuel compositions containing tetralin hydroperoxide were increased by about 3 to 5, as compared with that of the fuel composition containing no additive.
• the fuel composition of the present invention may be produced by using, as the starting material, an oil containing a high proportion of aromatic hydrocarbons and hence having poor combustibility, and modifying it through a very simple means.
• the present invention makes it possible to widen the application of materials which have hitherto been unsuitable for use in diesel engine fuels.
• the cetane number improver additive of the present invention may be readily prepared, is easy to handle ⁇ and can exhibit a marked effect.

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• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
• Liquid Carbonaceous Fuels (AREA)

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Citations (6)

• 1987
  • 1987-07-30 JP JP62189016A patent/JP2535178B2/ja not_active Expired - Lifetime
• 1988
  • 1988-03-23 DE DE8888302532T patent/DE3863393D1/de not_active Expired - Lifetime
  • 1988-03-23 EP EP19880302532 patent/EP0293069B1/fr not_active Expired

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