EP0562840A1

EP0562840A1 - Synthetic diesel oil

Info

Publication number: EP0562840A1
Application number: EP93302238A
Authority: EP
Inventors: Chen Zheng
Original assignee: Individual
Current assignee: Individual
Priority date: 1992-03-26
Filing date: 1993-03-24
Publication date: 1993-09-29
Also published as: CN1076716A; CA2091856A1; CN1030205C; AU3527993A

Abstract

A synthetic diesel oil particularly suitable for use in high cold areas is prepared by mixing heavy benzol as main raw material with an appropriate amount of kerosene and cetane number modifier. A small amount of freezing point depressant may be added to adjust the freezing point of the synthetic diesel oil.

Description

The present invention relates to a synthetic diesel oil which is particularly suitable for use with diesel engines in high cold areas as well as ordinary areas.
Diesel oil fuel is obtained mostly by refining of petroleum. The products are limited by the petroleum reserves. With the development of industry, agriculture, communications and transportation, and the improvement of the living standards of human beings, the contradictions between the supply and demand for diesel oil are becoming increasingly acute. To solve this problem, synthetic liquid fuels have been developed in China and abroad recently. One kind of this liquid fuel uses methanol as main raw material and can be used as a substitute for natural gasoline or diesel oil, as disclosed in U.S.P. 4,336,023, U.S.P.4,300,912, U.S.P. 4,298,352 and CN 87104075, wherein the main components in the formulations include hydrocarbons, mixtures of polyoxyalkylenes, or polyethylene glycol fluid etc., in addition to methanol, ethanol or butanol. The disadvantages of this kind of fuel are as follows: The starting materials are chemical raw materials with high price and currently in short supply; the combustion of the product is not complete, resulting in deficiency of power and black exhaust smoke; the climbing ability and the performance in overload are poor; and the corrosive and abrasive effects on the engine.
The second kind of the fuel is a synthetic diesel oil using refined tar oil as main raw material, as disclosed in U.S.P. 4,673,411, CN 88109773 and CN 90101391, wherein the components in the formulations include kerosene and a small amount of alcohol, ether or alkylnitrate etc. in addition to the refined tar oil. Although the main raw materials are easy to obtain, this kind of synthetic diesel oil still has disadvantages, such as, poor combustion performance, air pollution by black exhaust smoke and abrasion to engine. Therefore, the above two kinds of synthetic fuel have not actually been widely used until now. The third kind of fuel is a synthetic liquid fuel prepared by mixing toluene as main raw material with alcohol, and is most close to that of this invention. It has a working performance close to that of gasoline, and is suitable for use in gasoline internal combustion engine.
The object of this invention is to provide a synthetic diesel oil, which contains heavy benzol as a main component and is particularly suitable for use in high cold areas.
According to the present invention, a synthetic diesel oil is provided comprising 35 to 60 parts by volume of heavy benzol, 20 to 35 parts by volume of kerosene and 2 to 27 parts by volume of cetane number modifier.
Heavy benzol, being a main component and a byproduct of oil refinery and coking plant, is a mixture of mesitylene, indene and benzofuran, and can be obtained at low cost by distilling a residue of the petroleum industry, crude benzole, as distillate at 150-200°C. The heavy benzol is preferably present in an amount of 38 to 43 parts by volume in the oil of the invention.
The keresone used in the invention may be cracked or illuminating kerosene, depending on the desired freezing point of the products. In general, preferably the cracked kerosene is used for products with low freezing point, and the illuminating kerosene for products with high freezing point. The kerosene mainly plays a role of initiator in the invention, while the cracked kerosene also has an effect of depressing freezing point in a certain degree. The kerosene is preferably present to an amount of 24 to 30 parts by volume in the oil of the invention.
The cetane number modifier used in the invention can be one or more materials selected from nitrates or nitrites, such as pentyl nitrate or isopentyl nitrite etc; nitroalkanes, such as nitrobutane or nitrooctane; or isomeric hydrocarbons, natural light diesel oil or heavy diesel oil. An appropriate amount of the modifier may be added to adjust the cetane number of synthetic diesel oil to be in the range of 20-50. The added amount of the modifier is generally more than 20 parts for natural diesel oil and less than 10 parts totally for the abovementioned other materials. Preferably the added natural diesel oil as the modifier is from 20 to 27, and the added other materials as the modifier are from 2 to 10. From the point of view of commerciality, the cost is lower to use the natural diesel oil as the cetane number modifier. In general, heavy and light diesel oils are preferably used for low speed and high speed diesel engines respectively, to adjust the cetane number.
According to the present invention, the synthetic diesel oil may include a freezing point depressant. The freezing point depressant used in the synthetic diesel oil can be any one of materials selected from ethylene-vinyl acetate copolymer or alkyl naphthalene. If no freezing point depressant is added, a freezing point corresponding to No. 0 diesel oil in GB 252-87 can be reached, while the synthetic diesel oils with freezing points corresponding to those of No. -10. -20. -35, -50 or above diesel oils can be obtained, respectively, by adding about 0.01-3 parts by volume of the freezing point depressant.
The process for preparing the diesel oil of this invention is simple and conventional. The process comprises the following steps:

(1) mixing the selected raw materials,
(2) adding a small amount of precipitant,
(3) stirring the mixture in a conventional manner,
(4) centrifuging the mixture or keep it standing,
(5) filtering in a conventional manner.

The precipitant used in the process promotes the precipitation of impurities. Preferably, it may be selected from sodium hydroxide or sodium dihydrogen phosphate, more preferably sodium dihydrogen phosphate. The precipitant is preferably in the form of a crystalline solid with industrial purity of more than 98% and added directly into the mixed solution of the components of the synthetic diesel oil in an amount of 0.1-0.5% based on the total weight of the components of the synthetic diesel oil during the preparation process.
The stirring step may take a few minutes or longer. When the mixture is treated with centrifugal equipment, the centrifuging step takes a short time. Alternatively the mixture may be kept still for days before the filtering step takes place. The process is performed at room temperature or just below at atmospheric pressure.

Example 1

380 L of heavy benzol, 350 L of illuminating kerosene and 270 L of light diesel oil were mixed in a 1500 L container at a temperature of 18°C. 5kg of crystalline solid sodium hydroxide with industrial purity of 98% was added into the mixture. The mixture was then stirred with a conventional electrical stirrer for about 10 minutes, and the mixture then kept still for 72 hours. The mixture was filtered, the resulting product, about 1000 L, being a transparent red brown liquid.
A synthetic diesel oil corresponding to the No. 0 synthetic diesel oil in GB 252-87 was prepared according to the above process. It was designated as sample oil No. 1 in quality test.

Example 2

The samples of Example 2 were made with the same process as Example 1. The starting materials contained 60 L of heavy benzol, 34 L of illuminating kerosene, 4.6 L of pentyl nitrate, and 1.4 L of alkyl naphthalene; 0.1% by weight of sodium dihydrogen phosphate was added, based on the total weight of the starting materials.
A synthetic diesel oil corresponding to the No. -10 synthetic diesel oil in GB 252-82 was prepared according to the above process. It was designated as sample oil No. 2 in quality test.

Example 3

The samples were prepared with the same method as Example 1. The starting materials contained 55 L heavy benzol, 35 L cracked kerosene, 4.5 L nitrobutane, 3.0 L nitrooctane and 2.5 L alkyl naphthalene, 0.1% by weight of sodium dihydrogen phosphate was also added, based on the total weight of all the starting materials.
A synthetic diesel oil corresponding to the No. -20 synthetic diesel oil in GB 252-87 was prepared according to the above process. It was designated as sample oil No. 3 in quality test.

Example 4

The samples were made with the same method as Example 1. The starting materials were 45 L heavy benzol, 34 L cracked kerosene, 20.7 L heavy diesel oil and 0.2 L ethylene-vinyl acetate copolymer. 0.3% by weight sodium dihydrogen phosphate was also added, based on the total weight of all the starting materials.
A synthetic diesel oil corresponding to the No. -35 Synthetic diesel oil in GB 252-87 was prepared according to the above process. It was designated as sample oil No. 4 in quality test. This product is suitable for use with low speed diesel engine in winter.

Example 5

The samples were prepared with the same method as Example 1. The starting materials were 50 L heavy benzol, 27.6 L cracked kerosene, 22 L light diesel oil and 0.4 L ethylene-vinyl acetate copolymer. 0.2% by weight of sodium dihydrogen phosphate was also added, based on the total weight of all the starting materials.
A synthetic diesel oil corresponding to the No. -35 synthetic diesel oil in GB 252-87 was prepared according to the above process and was designated as sample oil No. 5 in quality test. This product is suitable for use with high speed diesel engine in winter and in high cold areas.

Example 6

The samples were prepared with a method similar to Example 1. The starting materials were: 42.5 L heavy benzol, 30 L cracked kerosene, 27 L light diesel oil and 0.5 L ethylene-vinyl acetate copolymer. 0.2% by weight of sodium hydroxide was added, based on the total weight of the starting materials.
A synthetic diesel oil with a freezing point higher than the specified freezing point for No. -50 synthetic diesel oil in GB 252-87 was prepared according to the above said process and was designated as sample oil No. 6 in quality test. This product is suitable for use with speed diesel engine in winter and in ultra high cold areas.
The sample oils in Examples 1 to 6 were subjected to a test for quality index, the determined results of freezing point; cold filtering point; pour point; flash point; density an kinetic viscosity; sulfur, carbon, water and mechanical impurity content: acidity and alkality; degree of corrosion; colour, and cetane number, are shown in Table 1. The data indicates that the specified indexes for the future diesel oil have essentially been achieved.
The No. 4 and No. 5 synthetic diesel oils of the sample oils were charged into a 6 ton "Hino" truck, a 4 ton "Isuzu" truck and a walking tractor, respectively, to carry out the running test for 100 and 500 km. The starting characteristic, power characteristic, fuel consumption per 100 km, performance of exhaust smoke, and the corrosion and abrasion of the engine parts were examined. The results show that:

1. The starting sensitivity is 1 to 2 times of that of the natural diesel oil. In particular, the walking tractor can be started normally at an air temperature as low as -8°C by using this fuel, obviously superior to that of the natural diesel oil in the starting characteristic.
2. The power characteristics determined by running test with no load, full load and overload, respectively, demonstrate that the combustion of the fuel is uniform, running is smooth, and normal running in a grade angle of 17° can be achieved by using any one of three gears.
3. The fuel consumption per 100 km is slightly less than that of natural diesel oil. The determined data are as follows: for 5 ton "Isuzu" truck, the synthetic diesel oil is 13.5 L per 100 km, natural diesel oil is 14 L per 100 km, for 6 ton "Hino" truck, the synthetic diesel oil is 17.5 L, natural diesel oil is 18 L per 100 km.
4. The amount of exhaust smoke is lower than the National Standard. No dust or smoke can be detected by visual observation.
5. After running test, no abnormality was found on examination of the fuel injector, the fuel pipe of high pressure pump and the injector rubber ring.

The fuel of this invention shows many advantages, such as, appropriate cetane number, good ignition characteristic, high combustion efficiency, low amount of exhaust smoke, moderate freezing point and viscosity, no water and mechanical impurities, simple preparation process and equipment, and easy availability from residues from the petroleum and chemical industry, making the synthetic diesel oil of this invention low in cost and thus highly competitive in the market.

Claims

A synthetic diesel oil comprising 35 to 60 parts of heavy benzol, 20 to 35 parts of kerosene and 2 to 27 parts of cetane number modifier, all by volume.
The synthetic diesel oil as claimed in Claim 1, wherein the synthetic diesel oil further comprises 0.01 to 3 parts by volume of freezing point depressant.
The synthetic diesel oil as claimed in Claim 1 or Claim 2, wherein the cetane number modifier is one or more selected from the group consisting of nitrates, nitrites, nitroalkanes, isomeric hydrocarbons, natural light diesel oil and heavy diesel oil.
The synthetic diesel oil as claimed in Claim 3, wherein the cetane number modifier is natural light diesel oil or natural heavy diesel oil.
The synthetic diesel oil as claimed in any of Claims 2 to 4, wherein the freezing point depressant is ethylene-vinyl acetate copolymer or alkyl naphthalene.
The synthetic diesel oil as claimed in any of Claims 1 to 5, wherein the heavy benzol is present in an amount from 38 to 43 parts by volume.
The synthetic diesel oil as claimed in any of Claims 1 to 6, wherein the kerosene is present in an amount from 24 to 30 parts by volume.
The synthetic diesel oil as claimed in any of Claims 1 to 7, wherein a precipitant is used in preparation of the synthetic diesel oil in the precipitant is added in an amount from 0.1 to 0.5% by weight based on the total weight of the components of the synthetic diesel oil.
The synthetic diesel oil as claimed in Claim 8, wherein the precipitant is sodium hydroxide or sodium dihydrogen phosphate.