CN1261535C - Method for preparing gasoline with low content of olefin by modifying direct distillation gasoline - Google Patents

Abstract

The present invention relates to a method for preparing gasoline with low olefin content by modifying straight-run gasoline, which comprises the steps: the mixture is in contact reaction with a catalyst containing HZSM-5 under the conditions of 0.2 to 0.6MPa and 300 to 500 DEG C after the straight-run gasoline is mixed with the fraction of carbon four olefin; dry gas, liquid gas and gasoline components are then separated from products. The method can effectively utilize the component of carbon four in smelting plants to modify straight-run gasoline, and the gasoline component with high octane number and low olefin content is produced.

Description

Method for preparing gasoline with low olefin content by upgrading straight-run gasoline

technical field

The present invention is a method for preparing clean motor gasoline components with low olefin content, in particular, it is a method for producing high-octane gasoline containing only a very small amount of olefins by utilizing C4-olefins and low-octane straight-run gasoline Method for cleaning gasoline components.

Background technique

With the improvement of environmental protection requirements, my country has proposed new standards for the composition of motor gasoline, requiring that the content of olefins in gasoline is less than 35 mass%, the content of aromatics is not more than 40 mass%, and the content of benzene is not more than 2.5 mass%. However, the finished gasoline currently on the market in my country is mainly FCC gasoline, and its olefin content is much higher than 35% by mass. Therefore, reducing the olefin content of refined oil has become an urgent need for refineries. Traditional methods to reduce the olefin content of refined oil include catalytic reforming of naphtha, isomerization of light gasoline, and hydrocracking. For small and medium-sized refineries lacking hydrogenation and reforming units, it is an effective method to reduce the olefin content of catalytic gasoline by adopting the method of upgrading straight-run gasoline to increase the octane number for blending catalytic cracking gasoline. The modified gasoline produced can also be sold as low olefin content finished gasoline.

CN1032697C discloses a catalytic reforming-aromatization method for low-quality gasoline, using modified ZSM-5 molecular sieve as the catalyst active component, and the modifying agent is two or three of Zn, Al or rare earth metals. This method can convert straight-run gasoline into gasoline blending components with high aromatics content. It adopts a multi-stage reaction process, and the raw materials enter the first reactor. The reaction is carried out under the condition of hydrogen, the product is separated from gas and liquid, and the liquid above C5 is fractionated to obtain gasoline fraction, and the gas less than C4 in the reaction product is aromatized in the second reactor under the condition of 480- 650°C, 0.05-1.5MPa, volumetric space velocity 20-2000, the aromatized product is separated from gas and liquid to obtain hydrogen-rich gas and aromatic hydrocarbon mixture. This method effectively utilizes the low-molecular hydrocarbons produced during the upgrading process of inferior gasoline to increase the liquid yield and octane number of gasoline, but the aromatized product contains more heavy fractions and has a high dry point, which needs to be cut and reacted. The dry gas yield is as high as 7%. The one-way life of the catalyst is about two weeks, requiring multiple reactors to switch and regenerate in turn, and the investment in the device is relatively high.

"Refining Design" Volume 31, Issue 2, Pages 23-25, Volume 32, Issue 1, Pages 26-27, and Issue 5, Pages 7-9 successively reported the isomerization technology for increasing the octane number of straight-run gasoline. The technology uses straight-run gasoline upgrading catalysts to make straight-run gasoline undergo isomerization and aromatization reactions, and can upgrade straight-run gasoline with a motor octane number (MON) of 47.6 to a research octane number (RON) For 90% gasoline products, the olefin content is about 14%, the aromatic content is 15%, and the dry gas and loss are about 3-13%.

Due to the limited source of straight-run gasoline raw materials, it is not easy to fully meet the needs of refineries for reducing olefins in gasoline. With the development of polyolefin production, many refineries currently use light olefins in liquefied gas for the production of polypropylene, resulting in too much carbon four components, especially heavy carbon four mainly composed of butene-2. Due to the high olefin content, heavy components, low vapor pressure and poor combustion quality of some heavy carbon tetracarbonate, they are not sold well as civil liquefied gas fuels. How to improve the utilization value of heavy carbon four components in catalytic cracking products is an urgent problem for refineries to solve. If the heavy carbon four components are converted into clean gasoline, it can make up for the shortage of straight-run gasoline raw materials.

The superposition reaction of light olefins is a relatively mature technology for gasoline production, but the superposition reaction product is highly unstable gasoline dominated by olefins, which is easy to form polymer by-products and must be hydrotreated. For example, CN1381549A uses mixed C4 as a raw material to pass through two reactors connected in series, and adopts a two-stage reaction method to increase the C4-olefin oligomerization conversion rate to more than 90%, and the gas obtained by the reaction is mainly butane. It can be directly used as fuel, and the liquid-phase product obtained by the reaction contains more than 96% isooctene, and iso-octane with high octane number can be generated by hydrogenation. The oligomerization catalyst used in this method is solid phosphoric acid, HZSM-5 or silicon-aluminum pellets, and the conditions for carbon tetraolefin oligomerization are 160-230°C, 3.0-5.0MPa, and feed space velocity 0.5-6.0h ^-1 . The catalyst for the hydrogenation reaction of isooctene is a nickel catalyst supported on alumina or zeolite carrier. The conditions of the hydrogenation reaction are 200-300°C, 2.5-6.0MPa, space velocity 1.0-5.1h ^-1 , hydrogen/isooctene The volume ratio of ene is 100-800.

USP 4,950,387 provides a method for improving the quality of catalytic cracking (FCC) gasoline components by using C ₂ -C ₅ olefin upgrading reaction. In this method, catalytic cracking products are fractionated to obtain a gasoline fraction with a boiling point of 90-170°C and a high olefin content, and then this fraction is divided into two parts, one part is mixed with C ₂ -C ₅ olefins, and enters the fluidized bed The reactor reacts in the presence of an acidic catalyst to produce upgraded gasoline, which is then blended with another part of unmodified middle distillate gasoline to become product gasoline. The catalyst used for upgrading contains zeolite with a constraint index of 1-12, selected from ZSM-5, ZSM-11, ZSM-22, ZSM-23, ZSM-35 or ZSM-48, and the modification reaction condition is 260-399°C , 0.5-1.1 MPa, and the space velocity calculated on the basis of C ₄ ^-light olefins is 0.5-1.0 h ^-1 . When the catalyst is used, it must be regenerated by burning charcoal continuously.

Contents of the invention

The purpose of the present invention is to provide a method for modifying straight-run gasoline by blending carbon tetraolefin components. The method can increase the gasoline yield and reduce the dry gas yield while increasing the gasoline octane number.

The method provided by the invention comprises mixing the straight-run gasoline and the carbon tetraolefin fraction, contacting and reacting with the catalyst containing HZSM-5 at 0.2-0.6MPa and 300-500°C, and then separating the dry gas, Liquefied gas and gasoline components.

The present invention uses the C4 fraction and straight-run gasoline as raw materials, and under the action of a solid acid catalyst, the butene in the C4 fraction undergoes oligomerization and aromatization reactions, and the straight-run gasoline undergoes selective cracking and isomerization A series of modification reactions such as and aromatization, in which the hydrogen generated by the reaction of straight-run gasoline can be directly used in the hydrogenation reaction of butene oligomers to generate isoparaffins. For the two raw materials used in the present invention, the oligomerization of butene is an exothermic reaction, and the modification of straight-run gasoline is an endothermic reaction, and the thermal effects of the two reactions cancel each other out, reducing the thermal effect of the overall reaction, so no intermediate heater is needed Supplement heat for the catalyst in the reactor, the process is simple and the operation is simple.

In addition, the method of the present invention uses a catalyst with appropriate acidity to react the raw materials, so that the yield of gasoline reaches 60-75% by mass, the yield of liquefied gas reaches 23-37% by mass, and the low-value by-product—dry gas (C ₁ -C ₂ Hydrocarbons and a small amount of hydrogen) yield 0.3-2.0% by mass. The research method octane number of the gasoline produced is 86-90, the olefin content is less than 5% by volume, generally less than 2.5% by volume, the benzene content is not more than 1.5% by mass, and the total aromatic content is less than 40% by mass. It meets the requirements of environmental protection, and can be directly shipped as No. 90 gasoline, and can also be used to reconcile catalytic cracking gasoline with high olefin content to reduce its olefin content. The liquefied gas produced is mainly propane and butane, and the olefin content is 2-10% by mass. It is high-quality liquefied gas and meets the standard of liquefied gas for vehicles.

Description of drawings

Fig. 1 is a schematic flow chart of the method of the present invention.

Detailed ways

The reaction raw materials used in the present invention are C4-olefin fractions and straight-run gasoline, and the C4-olefins content in the C4-olefin fractions is 40-90% by mass, and the rest are _C3 - _C5 alkanes and propylene. The preferred C4 fraction contains 60-90% by mass of butene, with the remainder being butane, propylene, propane and pentane.

The straight-run gasoline is low-octane gasoline produced by a refinery, and its research octane number is generally lower than 60. The boiling range of the straight-run gasoline is 38-170°C, and the alkane content is 50-69% by mass. The cycloalkane content is 30-40% by mass, and the aromatic hydrocarbon content is 1-10% by mass.

During the reaction process, in order to effectively utilize the heat of reaction, the mixing ratio of straight-run gasoline and mixed C4-olefin fractions should be controlled to be 2-6:4-8, and the mixing ratio of raw materials should be based on the butene content in C4-distillates , After mixing, the butene content in the raw materials should reach 15-55% by mass.

In the method of the present invention, the temperature for the contact reaction between the straight-run gasoline and the C4 fraction and the catalyst is preferably 320-450° C., and the pressure is preferably 0.2-0.4 MPa. The mass space velocity of the feed mixed with the straight-run gasoline and the C4 fraction into the catalyst bed is 0.1-1.0 h ^-1 . The reaction is carried out under non-hydrogen-facing conditions, and the raw materials can be used directly without further purification.

The active component of the catalyst used in the present invention is HZSM-5, the molar ratio of silicon to aluminum, that is, the molar ratio of silicon oxide to aluminum oxide, is 30-150, preferably 30-100, and aluminum oxide is used as a binder during molding. Therefore, the catalyst includes 40-80% by mass of HZSM-5 and 20-60% by mass of γ-alumina. In addition, in order to increase the anti-coking ability of the catalyst, a modified metal component can also be added. This catalyst includes 0.1-5.0% by mass of metal oxide, 37.5-80.0% by mass of HZSM-5 and 19.9-57.5% by mass of γ-alumina, the metal oxide is selected from oxides of zinc, antimony, mixed rare earths, bismuth, molybdenum or gallium, and the preferred modification component is antimony oxide or mixed rare earth oxides.

The mixed rare earth oxide contains 20-40% by mass of lanthanum oxide, 40-60% by mass of cerium oxide, 10-18% by mass of praseodymium oxide and 2-10% by mass of neodymium oxide.

The catalyst of the present invention can be formed by conventional methods of extruding strips, pressing tablets, dropping balls or rolling balls. When molding, firstly mix HZSM-5 zeolite powder and aluminum hydroxide powder evenly, then add appropriate amount of water and 1-3% by weight of nitric acid or acetic acid to knead and extrude into strips, or make the raw materials into a sol, and place them in a hot oil bath or The drop ball is formed in the oil ammonia bath. After molding, the material is dried at 60-120°C for 2-4 hours, and then calcined at 400-600°C for 2-8 hours.

When the catalyst contains a modified metal, the metal element can be introduced into the catalyst by impregnating with a soluble salt solution of the metal or ion exchange, and then calcined. The impregnation can be saturated impregnation or supersaturated impregnation, and the liquid/solid volume ratio of impregnation liquid to solid is 0.8-1.2:1 during impregnation. The soluble salt of the metal is selected from metal chloride or nitrate, wherein the soluble salt of misch is selected from chlorinated misch. In addition, the modifying metal can also be directly added in the form of oxide when the catalyst is shaped.

The catalyst also needs to be treated with water vapor to reduce its acidic cracking relative activity (α value) to 10-100, preferably 15-70. The α value indicates the relative activity of the catalyst for n-hexane cracking. (The determination method of α value is with reference to Yang Cuiding et al. edited "Petrochemical Analysis Method (RIPP Experimental Method)", published by Science Press, P255 "Constant Temperature Method Determination of α Value of Acidic Catalyst"). Properly controlling the α value of the catalyst can make the catalyst not only have good selective cracking activity, but also good stability and regeneration performance.

The condition for treating the catalyst with water vapor in the present invention is 450-600 DEG C, and the time is 2-12 hours. During the treatment, pure water vapor can pass through the catalyst bed, and the mass ratio of the total water consumption to the catalyst is 0.5-10. The steam treatment can be carried out before or after the catalyst is formed.

After the catalyst of the present invention is treated with water vapor, it has good stability and regeneration performance. Under the reaction condition of space velocity of 0.4 ^h The one-way reaction period of less than 3 volume % can reach more than 40 days.

The method of the invention is suitable for a fixed-bed semi-regenerative reaction device, and the dry gas, liquefied gas and gasoline components can be separated through simple separation of reaction products.

The process flow of the present invention will be further described below in conjunction with FIG. 1 . It can be seen from Fig. 1 that straight-run gasoline and C4-olefin fractions are respectively output by metering pump 1, and after mixing, pass through heat exchanger 4 and exchange heat with the reaction product from the bottom of reactor 3, and then enter heating furnace 2 to be heated to the reaction temperature. Then from the top of the reactor 3, it enters into contact with the catalyst, and the reaction raw material undergoes a reforming reaction under the action of the catalyst to generate high-octane gasoline, and at the same time, a part of high-quality liquefied gas is produced by-product. After heat exchange, it is cooled and separated into gas-liquid two phases in the flash tank 5. The rich gas at the top of the flash tank enters the middle part of the absorption desorption tower 6 after being compressed by the compressor, and the dry gas is discharged from the top of the absorption desorption tower 6 through the pipeline 9. system, the bottom material is mixed with the liquid separated from the bottom of the flash tank 5 and then enters the middle of the stabilization tower 7, where the liquefied gas and high-octane gasoline components are separated, and the liquefied gas is discharged from the top of the tower through the pipeline 10 , gasoline components are discharged from the bottom of the tower, part of which is pumped back to the top of the absorption and desorption tower as an absorbent, and the rest is discharged from the system through pipeline 8 as finished gasoline.

The present invention will be described in detail below by examples, but the present invention is not limited thereto.

Instance 1

The following examples prepare the catalysts used in the present invention.

(1) Prepare the carrier: get 120 grams of HZSM-5 zeolite powder (produced by Shanghai Huaheng Chemical Factory) with a silicon-aluminum ratio of 56, 80 grams of aluminum hydroxide powder (produced by Qilu Catalyst Factory), stir well, and add 4 ml concentration It is fully kneaded with 40% by mass of nitric acid and 100 ml of deionized water, extruded into strips with a diameter of 2 mm, dried at 110°C for 8 hours, cut into particles with a length of 2-3 mm, and then calcined at 570°C for 4 hours to obtain carrier.

(2) Introduce modified components: take 100 grams of the carrier prepared in step (1), use 100 milliliters of an aqueous solution containing 1.0 grams of mixed rare earth chloride (produced by Inner Mongolia Baotou Rare Earth Industry Company, which contains 14.6 mass % of lanthanum oxide, oxidized 24.0% by mass of cerium, 6.6% by mass of praseodymium oxide, 1.9% by mass of neodymium oxide, analyzed by X-ray fluorescence method) at 80°C for 2 hours, filtered, and the impregnated solution was removed, the solid was dried at 120°C for 8 hours, and baked at 550°C for 4 hours , to obtain a mixed rare earth modified catalyst.

(3) Water vapor treatment: put the mixed rare earth modified catalyst prepared in step (2) into a tubular reactor, heat up to 580°C in air flow under normal pressure, and then feed water vapor at this temperature Treated for 5 hours, the total water intake was 400 grams, and the prepared catalyst A contained 0.43% by mass of mixed rare earth oxides (X-ray fluorescence analysis, the same below), 64.33% by mass of HZSM-5, and 35.24% by mass of γ-Al ₂ O ₃ , the alpha value is 30.

Example 2

Catalyst B is prepared by the method of example 1, and difference is that the carrier that (1) step is made carries out steam treatment by the method for (3) step earlier, then introduces mixed rare earth by the method for (2) step, the catalyst obtained B contains 0.43% by mass of rare earth oxide, 64.33% by mass of HZSM-5, 35.24% by mass of γ-Al ₂ O ₃ , and an α value of 40.

Example 3

Catalyst C is prepared by the method of example 1, and difference is (1) step impregnates 100 gram carrier with the aqueous solution that contains 5.0 gram mixed rare earth chlorides with 100 milliliters, (3) step steam treatment time is 8 hours, and prepared catalyst C Contains 2.2% by mass of mixed rare earth oxides, 63.19% by mass of HZSM-5, 34.61% by mass of γ-Al ₂ O ₃ , and an α value of 56.

Example 4

Get 65 grams of HZSM-5 zeolite powder with a silicon-aluminum ratio of 56, 35 grams of aluminum hydroxide powder, and 2 grams of antimony oxide powder. After mixing evenly, press the method of Example 1 to extrude into strips, dry at 110°C for 2 hours, and roast at 580°C for 4 hours. Hour. Then steam treatment was carried out according to the method of step 1 (3) of Example 1 to prepare catalyst D, which contained 2.2% by mass of antimony oxide, 63.19% by mass of HZSM-5, 34.61% by mass of γ-Al ₂ O ₃ , and the value of α was 15.

Example 5

Get 130 grams of HZSM-5 zeolite powder (produced by Nankai University Catalyst Factory) that the ratio of silicon to aluminum is 79, 70 grams of aluminum hydroxide powder (produced by German Condea company, brand SB), knead and extrude by the method of example 1 (1) step , dried at 120°C for 2 hours, roasted in air at 570°C for 4 hours, then changed to steam at this temperature for 2 hours, and then changed to air to purge and cool down. The total water consumption of steam treatment was 150 grams. The prepared catalyst E contained 70.0% by mass of HZSM-5, 30.0% by mass of γ-Al ₂ O ₃ , and an α value of 35.

Instances 6-9

The following examples carry out C4 and straight-run gasoline upgrading reaction evaluation and process test.

In four identical 20 milliliters fixed-bed continuous flow reactors, each filling 20 milliliters, 14 grams of catalyst A, different proportions of C4 and straight-run gasoline are mixed to prepare mixed raw materials with different C4 contents, and feed them into three The reforming reaction is carried out in two reactors, and the reaction product enters the water cooler and is separated into two phases of gas and liquid, which are measured separately and analyzed for composition. Under the conditions of 380°C, 0.3MPa, and feed quality space velocity of 0.5h ^-1 , the upgrading reaction was carried out under non-hydrogen-facing conditions; at the same time, 100% straight-run gasoline was used as raw material in the fourth reactor, under the same conditions Conduct a comparative test. The composition of C4 used in the reaction is shown in Table 1, the composition of straight-run gasoline is shown in Table 2, and the reaction results are shown in Table 3.

It can be seen from Table 3 that when purely straight-run gasoline is used as the reaction raw material, the gasoline yield in the reaction product is the lowest, the content of aromatics is also low, and the _octane number is only 84.1. The yield of the gasoline has also been improved, especially the content of aromatics in gasoline is significantly increased, and the octane number of gasoline can be increased by 2-6 units accordingly, while the content of olefins in gasoline does not exceed 2.5% by mass. Therefore, mixing C4 into straight-run gasoline for upgrading can obtain higher-quality low-olefin gasoline products than simply using straight-run gasoline as a raw material for upgrading. The increase in gasoline yield shows that part of C4 is converted into gasoline, which makes up for the loss of liquid yield caused by the cracking of straight-run gasoline. It can be seen that refining C4 has a significant effect on increasing gasoline yield and improving economic benefits. At the same time, the olefin content in the liquefied gas components (C ₃ +C ₄ ) produced by the reaction is all lower than 5% by mass, which is high-quality liquefied gas and meets the quality standard of liquefied gas for vehicles.

Instances 10-13

In 20 milliliters of fixed-bed continuous flow reactors, fill 20 milliliters, 14 grams of catalysts B, C, D, E respectively, carry out reforming reaction with the mixed material of 40% carbon four and 60% straight-run gasoline as raw material, in The reforming reaction was carried out under non-hydrogen-facing conditions with a bed temperature of 350° C., 0.3 MPa, and a feed mass space velocity of 0.4 hr ⁻¹ . The reaction results of each example are shown in Table 4.

Example 14

Catalyst A's life experiment in C4 and straight-run gasoline upgrading reaction.

In a 40 milliliter fixed-bed continuous flow reactor, fill 35.7 milliliters, 25.0 grams of catalyst A, and carry out a single-pass life experiment of upgrading reaction with a mixture of 40% C4 and 60% straight-run gasoline as a raw material, and the reaction pressure is 0.3MPa , the reaction was carried out for 42 days (1002 hours) under the non-hydrogen-facing conditions of the feed mass space velocity of 0.4 hours ⁻¹ and the bed temperature of 340-420° C. The reaction results are shown in Table 5. It can be seen from Table 5 that after the catalyst has been used for 1000 hours, the research octane number of the obtained modified gasoline can still reach more than 85, and the olefin content is less than 1.5% by volume.

Table 1 C4 fraction hydrocarbon content, quality% Propylene 0.66 propane 0.07 1-Butene 0.10 Isobutylene 0.08 n-butane 10.09 2-butene 89.00 Pentane 0.10 total 100.00

Table 2 Straight-run gasoline hydrocarbon content, quality% Hydrocarbons below C4 5.12 Pentane 8.92 Hexane 16.81 Heptane 22.71 Octane 22.31 nonane 20.32 Decane 3.61 C11 alkane 0.20 total 100.00 Hydrocarbon group composition, quality% alkanes 58.6 Naphthenic 36.50 Aromatics 4.90 octane number Motor Law (MON) 54.0 Research Act (RON) 54.8

table 3 project Example 6 Example 7 Example 8 Example 9 Reaction raw material composition, mass% C4 content 20 40 60 0 Butene content 16.2 31.6 47.5 0.0 Product composition, mass % C ₅ ⁺ gasoline fraction 66.1 68.3 65.3 64.4 Liquefied gas (C ₃ +C ₄ ) 33.3 31.2 34.0 34.9 Dry gas (H ₂ +C ₁ +C ₂ ) 0.6 0.5 0.7 0.7 gasoline properties Octane number (RON) 86.5 88.3 90.6 84.1 Olefin content, volume % 0.8 0.8 2.1 1.2 Benzene content, mass% 1.4 1.1 1.4 1.4 BTX ^* content, mass % 21.7 22.7 25.4 19.3 Total aromatics content, mass% 30.3 32.6 33.8 26.5 Olefin content in liquefied gas, mass % 4.5 4.7 3.5 4.3

Note: BTX is benzene, toluene, xylene

Table 4 Example 10 Example 11 Example 12 Example 13 Catalyst number B C D. E. Dry gas, mass% 0.48 0.61 0.33 0.54 Liquefied gas, mass% 31.96 36.10 28.21 34.60 C ₅ ⁺ gasoline fraction, mass % 67.30 63.17 71.24 65.3 total 99.74 99.88 99.78 99.20 gasoline properties Olefin content, volume % 1.2 0.9 1.1 1.0 BTX content, mass% 20.54 23.90 19.37 21.60 Total aromatics content, mass% 31.16 37.58 30.84 34.5 Research Octane Number (RON) 87.7 89.6 86.6 88.7 Motor octane number (MON) 79.5 80.5 76.5 80.0 Olefin content in liquefied gas, mass % 3.5 4.5 3.1 3.8

Survey 5 Response days 1-3 6-10 11-17 18-24 25-32 33-38 39-42 temperature, ℃ 340 370 380 390 400 410 420 Average dry gas yield, mass% 0.33 0.5 0.58 0.67 0.75 0.95 1.03 Stable gasoline octane number and olefins and aromatics content changes in each temperature range RON 89.4 86.9 88.7 88.8 87.9 86.6 85.2 MON 80.2 78.5 79.6 79.9 78.9 77.8 76.9 Olefin content, volume % 1.5 2.2 1.1 1.4 1.1 1.0 1.4 Aromatic content, mass% 33.1 28.4 33.5 34.1 32.9 33.2 29.8

Claims (11)

1, a kind of straight-run spirit upgrading prepares the method for gasoline with low olefine content, comprise straight-run spirit with after the C 4 olefin fraction mixes, under 0.2-0.6MPa, 300-500 ℃ condition with contain the catalyzer contact reacts of HZSM-5, the dry gas in the separated product, liquefied gas and gasoline component then.

2, in accordance with the method for claim 1, it is characterized in that C 4 olefin content is 40-90 quality % in the described mixed c 4 alkene fraction, all the other are C ₃-C ₅Alkane and propylene.

3, in accordance with the method for claim 1, it is characterized in that containing in the described mixed c 4 alkene fraction butylene of 60-90 quality %, all the other are butane, propylene, propane and pentane.

4, in accordance with the method for claim 1, it is characterized in that alkane content is 50-69 quality % in the described straight-run spirit, naphthene content is 30-40 quality %, and aromaticity content is 1-10 quality %, and research octane number (RON) is lower than 60.

5, in accordance with the method for claim 1, after it is characterized in that straight-run spirit and the C 4 olefin fraction mixing, butene content wherein is 15-55 quality %.

6, in accordance with the method for claim 1, it is characterized in that the charging mass space velocity that straight-run spirit and C 4 olefin fraction are mixed into beds is 0.1-1.0 hour ^-1, temperature of reaction is 320-450 ℃, pressure is 0.2-0.4MPa.

7, in accordance with the method for claim 1, it is characterized in that described catalyzer comprises the HZSM-5 of 40-80 quality % and the gama-alumina of 20-60 quality %.

8, in accordance with the method for claim 1, it is characterized in that described catalyzer is made up of the metal oxide of 0.1-5.0 quality %, the HZSM-5 of 37.5-80.0 quality % and the gama-alumina of 19.9-57.5 quality %, described metal oxide is selected from the oxide compound of antimony or mishmetal.

9, in accordance with the method for claim 8, it is characterized in that containing in the described mixed rare-earth oxide lanthanum trioxide of 20-40 quality %, the cerium oxide of 40-60 quality %, the Praseodymium trioxide of 10-18 quality % and the Neodymium trioxide of 2-10 quality %.

10, according to described any one method of claim 7-9, it is characterized in that described catalyzer need carry out steam-treated, make its acidic cleavage relative reactivity α value be 10-100.

11, in accordance with the method for claim 10, it is characterized in that described steam-treated condition is 450-600 ℃, the time is 2-12 hour, and the mass ratio of total water amount and catalyzer is 0.5-10 during processing.