RU2010837C1 - Method of recovery of high antiknock gasoline and aromatic hydrocarbons - Google Patents

Abstract

FIELD: petrochemistry. SUBSTANCE: wide and narrow gasoline fractions containing predominantly C₇-C₁₀ and C₆-C₇ hydrocarbons, respectively, are subjected separately to catalytic reforming. Benzene-containing fraction isolated from wide fraction liquid reformats through rectification and containing 2-50% isohexanes out of the potential in liquid reformat, are co-treated along with narrow fraction reforming gas product. Co-treatment is accomplished in the presence of catalyst containing pentasil zeolites and/or erionite under narrow fraction reforming pressure and 250-460 C and at a 700-2000 n. vol/vol ratio of hydrogen-containing gas to a mixture of gasoline with benzene-containing fraction. Low- molecular aromatic hydrocarbons are isolated from the product obtained through extraction or extractive rectification. Upon extraction, liquid product is mixed totally or partially with wide gasoline fraction liquid reformats after benzene fraction has been isolated. EFFECT: recovery of high antiknock gasoline and aromatic hydrocarbons improved. 2 cl, 2 tbl

Description

 The invention relates to oil refining, and more specifically to methods for producing high-octane gasoline and aromatic hydrocarbons based on reforming catalysts of wide fractions.

For the production of high-octane gasoline, wide gasoline fractions are subjected to reforming on platinum-containing catalysts, boiling in the range from 60-90 ^о С (the beginning of boiling) to 160-180 ^о (the end of boiling). Such raw materials contain C ₆ -C ₁₀ hydrocarbons, mainly (not less than 70%) C ₇ -C ₁₀ .

Reforming is carried out at 460-550 ^{° C} and pressures up to 4MPa. The liquid reforming products after cooling and separation are separated from the circulating reforming gas and subjected to stabilization (debutanization). Stable catalysis is used as high-octane gasoline or its component (1-3). The reforming catalysts of gasoline fractions contain non-aromatic and aromatic hydrocarbons, including some benzene, depending on the hydrocarbon composition of the feed and the reforming mode, the benzene content can be in the range of 1-8%.

 Benzene degrades the environmental performance of gasoline, but at the same time it is a valuable product for the industry of organic synthesis and the production of synthetic materials.

For the benzene and other aromatic hydrocarbons narrow reformed gasoline fractions, such as 62-105 ^{° C} to produce benzene, toluene or 62-140 ^{° C} to produce benzene, toluene, xylene. Common is the use of raw materials containing predominantly C ₆ -C ₇ hydrocarbons (at least 70%). Aromatic hydrocarbons are isolated from reforming catalysts by extraction or extractive pectification, while the non-aromatized portion remains - raffinate. Raffinate has low octane characteristics and is used for the production of low-octane gasolines and as solvents (2-3).

 In industry, the majority of gasoline fractions are used to produce motor gasolines; therefore, the capacity of plants for raw materials for gasoline production is significantly (2-3 times) higher than for the production of aromatic hydrocarbons. The main objectives of reforming gasoline production are to increase the octane number and reduce the content of aromatic hydrocarbons and especially benzene.

 Known methods for increasing the octane number of reforming catalysts using selective hydrocracking, carried out on catalysts whose cracking base is geometrically selective zeolites, such as chabazite, gmelenite, pentasil, erionite (4-6), lead to an undesirable increase in the content of aromatic hydrocarbons and, in particular including benzene.

The closest in technical essence to the proposed invention is a method for motor gasoline and aromatic hydrocarbon, comprising reforming wide (62-180 ° ^C) gasoline fraction, separation of liquid product reformate benzene distillation (60-95 ° ^C), a benzene-toluene (60 -120 ° ^C) or a benzene-toluolno- xylene (60-150 ° ^C) fractions, sending them to ekstruktsiyu or extractive distillation to separate aromatics and unscented offset portion with the other products rifor Inga (7).

However, the removal of aromatic hydrocarbons leads to a decrease in the octane number of gasoline. Especially when mixed catalysate without benzene fraction (60-95 ° ^C) with this raffinate fraction octane number decreases relatively little 0.6 n., But reduction of aromatics slightly, only 1.2%. In other cases, when it is possible to significantly reduce the content of aromatic hydrocarbons, the octane number of gasoline sharply decreases. Thus, the disadvantage of this method is its low efficiency, the removal of benzene from the reforming catalysis and its preparation as one of the products leads only to a slight decrease in the content of aromatic hydrocarbons and then with a decrease in the octane number. Therefore, it is necessary to introduce expensive alkylate or other fractions of gasoline into gasoline.

 The proposed method provides for the production of gasolines with a low content of aromatic hydrocarbons in the practical absence of benzene without a significant reduction or increase in their octane number. At the same time, the output of the most valuable aromatic hydrocarbons increases.

This goal is achieved by the proposed method for producing high-octane gasoline and aromatic hydrocarbons, according to which separately wide and narrow gasoline fractions are subjected to catalytic reforming, containing mainly C ₇ -C ₁₀ and C ₆ -C ₇ hydrocarbons, respectively, isolated by rectification from liquid products of reforming a wide fraction an intermediate benzene-containing fraction containing 2-50% of isohexanes from the potential in the liquid product of the reforming, 1-25% of toluene from its potential in the liquid product of the reef Ming processed together with the gas-product stream emerging from the reforming zone a narrow fractions in the presence of a catalyst comprising pentasil zeolite and / or erionite at a pressure reforming narrow fractions temperature of 250-460 ^C and a ratio of the water-containing gas mixture to the gasoline and narrow benzene fraction 700-2000 and about / about. , low molecular weight aromatic hydrocarbons are isolated by extraction or extractive distillation from the product of the joint septum, the remaining liquid product is completely or partially mixed with the rest of the liquid reforming products.

A comparative analysis with the prototype allows us to conclude that the claimed method differs from the known one in that separately wide and narrow fractions are predominantly subjected to catalytic reforming, containing mainly C ₇ -C ₁₀ and C ₆ -C ₇ hydrocarbons, respectively.

the benzene-containing fraction contains 2-50% of isohexanes of potential in the liquid reforming product
the benzene-containing fraction is processed together with the gas product stream leaving the narrow fraction reforming zone in the presence of a catalyst containing pentasil and / or erionite
the temperature of the joint processing of 250-460 ^about With the ratio of hydrogen-containing gas to a mixture of narrow and benzene-containing fractions of 700-2000 N. about. /about.

 for mixing with the rest of the liquid reforming products of a wide fraction, a part or all of the liquid product of co-processing is sent after separation of low molecular weight aromatic hydrocarbons from it.

 A preferred feature of the invention is the content in the benzene-containing fraction of 1-25% of toluene from its potential in the liquid product of the reforming of a wide fraction.

 Thus, the claimed method meets the criteria of the invention of "novelty."

 The proposed method is as follows.

Straight-wide gasoline fraction containing mainly hydrocarbons C ₇ -C _10, after the hydrotreatment was subjected to catalytic reforming in the presence of catalysts alyuminoplatinovyh (with or without promoters) under known conditions at a temperature of 480-530 ^C and the pressure to 4 MPa. A hydrotreated narrow gasoline fraction is predominantly subjected to catalytic reforming, containing predominantly C ₆ -C ₇ hydrocarbons under a pressure below 2 MPa and other conditions mentioned above. The installation is equipped with an additional reactor through which the gas-product mixture passes together with a recycle hydrogen-containing gas. An intermediate benzene-containing fraction is separated from the catalytic reforming of a wide fraction by distillation on two successively connected distillation columns.

However, it is possible to confine ourselves to one additional distillation column if the first stage of distillation is carried out in a debutanization column of unstable reforming catalytic converter of a wide fraction with the side stream of the C ₅ -C ₇ carbon fraction being withdrawn from it, which is sent to an additional column, the target benzene-containing fraction is removed from the cube, and the fraction of lighter hydrocarbons above. The method of isolating the benzene-containing fraction is not the subject of the invention, because it can be calculated on a computer.

 However, the compositional requirements of the benzene-containing fraction, expressed in the range of permissible amounts of isohexane from the potential in the liquid reforming product, is an important feature of the invention. This fraction preferably also contains toluene in the amount indicated above.

The specified fraction is sent to an additional reactor, where they, together with the gas product stream in the gas phase, are processed on a catalyst containing synthetic zeolite pentasil and / or erionite. Pentasil is a high molecular zeolite having pores with a diameter of about 5.6 C $\genfrac{}{}{0ex}{}{\text{+}}{\text{9}}$ formed by 10-membered rings of oxygen atoms, erionite has pores with a diameter of about 4 C $\genfrac{}{}{0ex}{}{\text{+}}{\text{8}}$ formed by 8-membered rings of oxygen atoms (8).

 Catalysts based on these zeolites contain a hydrogenation metal of the 6th and / or eighth group, for example molybdenum, in the form of an oxide, a metal of the platinum group. The quantitative composition of the catalyst is not an essential feature of the invention, it is only important that it contains at least 20% of these zeolites. The process conditions should be selected so as to prevent the hydrogenation of aromatic hydrocarbons.

The ratio of hydrogen-containing gas / raw materials (a mixture of a narrow gasoline fraction and a benzyl-containing fraction) should be in the range of 700-2000 N. about. /about. And the temperature in the range ^of 250-460 C. The process pressure determined by the pressure reforming narrow fraction, typically below 2 MPa.

The low molecular weight hydrocarbons extracted by extraction are benzene, and toluene, if necessary, C ₈ aromatic hydrocarbons are also obtained.

 The remainder of the co-processing liquid products, which are raffinate, higher aromatic hydrocarbons, are mixed with the liquid product of reforming a wide fraction from which the benzene-containing fraction has been previously removed.

 Thus, the proposed method allows to obtain high-octane gasoline with a low content of aromatic hydrocarbons, with virtually no decrease and even an increase in the octane number, although aromatic hydrocarbons have high octane numbers.

 The method meets the criterion of non-obviousness, because it does not follow from the known technical solutions.

EXAMPLE EXAMPLE 1. alyumoplatinorenievom reforming catalyst is subjected to a wide hydrotreated gasoline fraction 75-180 ^{° C,} containing 53.8% paraffins, 29.1% naphthenes and 17.1% aromatics. Hydrocarbons C ₇ -C ₁₀ in the feedstock make up wt. % 81 (rest C ₆ -C ₅ ). Reforming conditions: pressure 2.5 MPa, temperature of 480 ° ^C. Stable catalysate obtained in a yield wt. % 82, the octane number of catalysis is 83 p. method (91.5 p. according to the research method). The catalyst contains wt. % 54.7 aromatic hydrocarbons including 5.1% benzene. Separately subjected to catalytic reforming hydrotreated narrow fraction 62-105 ^{° C} under pressure of 1.6 MPa and other conditions mentioned above. The installation is equipped with an additional reactor connected in series after the reforming reactor. A gas product mixture passes through the specified reactor together with a recirculating water-containing gas.

The narrow gasoline fraction contains 69.6% paraffinic, 27.8% oil, 2.6% aromatic hydrocarbons. The hydrocarbon content of C ₆ -C ₇ in the feed is 97.6% (the rest is C ₅ and C ₈ ). On the basis of experimental and calculated data, flow rates in kg / h are carried out for illustration.

 Taking into account the ratios in the productivity of reforming units and narrow fractions in industrial practice, the productivity of raw materials for reforming a wide fraction is taken to be 2 times greater, respectively 100 and 50 kg / h. A benzene-containing fraction, which in addition to benzene and other hydrocarbons, contains 9.6% of isohexanes of the potential in the initial catalyst, is isolated from the reforming catalysis of a wide fraction by distillation. It also contains toluene 6.4% toluene of its potential in catalysis.

 At a productivity of 100 kg / h, 18.7 kg / h of the benzene-containing fraction and 63.3 kg / h of a mixture of the head and bottoms fractions of reforming catalysis are obtained from the reforming feedstock.

 The total yield of liquid reforming products of a wide fraction of 82 kg / h (82 wt.%). The rest is gaseous reforming products.

 In the table. 1 shows an exploded composition and a broads of isolation of a benzene-containing fraction.

18.7 kg / h of the isolated benzene-containing fraction is sent to an additional reactor connected to the narrow fraction reforming reactor. The temperature in the additional reactor is 300 ^° C; the ratio of hydrogen-containing gas per mixture of a narrow gasoline and benzene-containing fraction of 1200 n about. /about. A catalyst containing 60% n-pentasil, 5% MoO ₃ , and aluminum oxide was charged into an additional reactor.

Stable catalyzate in an amount of 59.96 kg / h is directed to extraction. 8.66 kg / h of benzene, 8.13 kg / h of toluene, 1.2 kg / h of C ₈ aromatic hydrocarbons and 1.7 kg / h of C ₉ ⁺ aromatic hydrocarbons and 40.27 kg / h of the dearomatized part of the catalyzate are obtained (raffinate). A mixture of raffinate with aromatic hydrocarbons With ₈ and above has an octane number of 70 p. By the motor method. The specified stream in the amount of 43.17 kg / h is mixed with 63.3 kg / h of the catalytic reforming of the wide fraction, previously freed from the benzene-containing fraction.

 Get 106.47 kg / h of gasoline with an octane rating of 83 p. Mot. the method and the content of aromatic hydrocarbons 41.3 wt. % The total production of benzene, toluene and high-octane gasoline is 123.26 kg / h, which is 82.17% of the total reforming feedstock of wide and narrow fractions.

 The example shows the possibility of producing high-octane gasoline with an octane number not less than the initial catalytic reforming of a wide fraction and a significantly lower content of aromatic hydrocarbons.

 The results obtained in this and subsequent examples are given in table. 2.

PRI me R 2. All conditions correspond to example 1 with the difference that for mixing with the benzene-free reforming catalyst, the wide fraction is used together with aromatic C ₈ ⁺ part of the raffinate in the amount of 13 kg / h. In this case, 76.3 kg / h of gasoline with an octane rating of 88.3 p. By the motor method (98.5 p. By the research method) are obtained with an aromatic hydrocarbon content of 53.6% lower than in the initial reforming catalyst. Excess raffinate can be used to produce less high octane gasolines.

 The example illustrates the possibility of varying the octane number of gasoline with the same release of aromatic hydrocarbons. The results are shown in table. 2.

PRI me R 3. All the conditions of example 1 with the difference that the joint processing is carried out at 460 ^about C, the ratio of hydrogen-containing gas / raw material 2000 N. about. / l in the presence of a catalyst containing 0.5 PT - 50% decatinized erionite, aluminum oxide - the rest.

 The results are shown in table. 2.

 The gasoline output with an octane rating of 85.6 p. (Mot. Met.) Is 96.34 kg / h with an aromatic content of 43.4 wt. % The release of benzene 9.5 kg / h, toluene 8.4 kg / h. The yield of liquid products on reforming feedstock is 76.9%.

 The example illustrates the upper limit of the preferred range of ratios of hydrogen-containing gas and temperature of joint processing, since the yield of liquid products is somewhat reduced.

 Example 4. From the reforming catalysis of examples 1, a benzene-containing fraction is isolated which contains 2% of the potential of isohexanes and 1% of toluene. All other conditions and the catalyst of example 1. (table. 2).

 When producing gasoline in terms of quality and quantity close to Example 1, the production of benzene and toluene is reduced. The example illustrates the lower limit of the range of isogensanes and toluene with a benzyl-containing fraction. Although the octane number of the obtained gasoline is slightly lower than in the initial reforming catalyst (by 0.9 percentage points), the content of aromatic hydrocarbons in it is significantly (by 13 abs.%) Lower, which gives a decisive advantage to the new method even with an extremely low degree of isohexanes and toluene.

 Example 5. From the reforming catalysis of a wide fraction, a benzene-containing fraction is isolated which contains 50% isohexanes and 25% toluene of the potential in the feed. The catalytic processing conditions and the catalyst correspond to example 1.

 The results (table. 2) are close to the results of example 1, but the yield of liquid products is slightly reduced (79.1%).

 PRI me R 6. The conditions and the catalyst correspond to example 1 with the difference that the ratio of hydrogen-containing gas to raw materials for additional joint processing of 700 N. about. /about. All the results on high-octane gasoline (output, oct. Number) are close to Example 1, which is noticeably lower than benzene 7.6 kg / h instead of 8.66 kg / h. Therefore, the gas / feed ratio is below 700 n. about. /about. impractical.

PRI me R 7. The conditions and the catalyst corresponds to example 2 with the difference that the temperature of the additional processing of 250 ^about C. As in example 2, 13 kg / h of raffinate with aromatic C ₈ ⁺ are used for mixing with the benzened reforming catalyst. Get the same amount of 76.3 kg / h of high octane gasoline with about. h. 87 p. with a lower aromatic content than in the initial reforming and slightly higher than benzene and toluene (see table. 2). Excess raffinate has a relatively low octane number (66 p. By the motor method). An example shows the inappropriateness of lowering the temperature below 250 ^about C.

PRI me R 8. All the conditions of example 1 with the difference that the temperature of the additional processing of 380 ^about C, and the catalyst contains 5 MoO ₃ - 30% erionite in decationized form, 20% N. pentasil, alumina - the rest. The results are placed in table. 2. The example illustrates the positive results both in the yield and characteristics of high-octane gasoline, and in the yield of benzene, at an intermediate processing temperature.

PRI me R 9 (prototype). Of the liquid product riforminta broad fraction was isolated by distillation of the benzene fraction is 62-95 ° ^C. The yield of this fraction is 19.9 kg / h including: isohexane 3, n-hexane, 3.9, 6.3 izpentanov, n-heptane 1 9, petroleum 0.7, benzene 4.0, toluene 0.1 kg / h. The octane number of the benzene fraction 56 p. On the bridge. method. At the same time, 62.1 kg / h of reforming catalysis, devoid of a benzene-containing fraction, is obtained. 3.9 kg / h of benzene is isolated from the benzene-containing fraction by extraction, while 16 kg / h of the non-aromatized portion of the catalysis remains, which is mixed with liquid reforming products of the wide fraction, 78.1 kg / h of gasoline with an octane rating of 82.5 bp are obtained mot. method and aromatic hydrocarbon content of 52.3%. The decrease in the content of aromatic hydrocarbons is negligible while reducing the octane number of catalysis.

 For comparison with examples 1-8, the known method for producing aromatic hydrocarbons by reforming a narrow fraction is added to the results of the prototype method.

When reforming a narrow fraction, the composition of which is shown in example 1, without additional processing, stable catalysis is obtained at 44 kg / h (88%). 5.7 kg / h of benzene, 7.7 kg / h of toluene, 1.2 kg / h of aromatic С ₈ , 29.4 kg / h of non-aromatic component (raffinate) are isolated by extraction by extraction. The raffinate together with aromatic C8 in the amount of 30.6 kg / h (octane number 60 p. By bridge. Method) is mixed with high-octane gasoline obtained by the prototype method. Get 108.7 kg / h of gasoline with an octane rating of 76 p. (By mot. Method). The content of aromatic hydrocarbons is 39.2%. At the same time, 9.6 kg / h of benzene and 7.7 kg / h of toluene are obtained.

 Total liquid products 126 kg / h or 84% on reforming feedstocks. The results are presented in table. 2.

 From the results obtained in example 9 it follows that by the method of the prototype it is impossible to obtain a significant reduction in the content of aromatic hydrocarbons in high-octane gasoline. If you dilute this gasoline with reformate from a gasoline fraction reforming unit, then the decrease in the content of aromatic hydrocarbons is accompanied by a strong (by 7 p.) Decrease in the octane number of gasoline, while in the proposed method the octane number even increases.

 The results are shown in table. 2. (56) Handbook of Petrochemistry, vol. 2. Ed. S.K. Ogorodnikova. M.: Chemistry, 1978, p. 148-166.

 Maslyansky G.N., Shapiro R.N. Catalytic reforming of gasolines, L.: Chemistry, 1985, p. 182.

 Sulimov A. D. Catalytic reforming of gasolines, M.: Chemistry, 1973, p. 53.

 GDR patent N 136397, CL C 10 G 37/10, 1967.

 U.S. Patent No. 3,926,782, 208-64, 1974.

 Shipikin V.V. et al. - Oil refining and petrochemicals, 1983, N 8, s, 3-4.

 Fedorov A.P. et al. - Chemistry and technology of fuels and oils, 1972, N 8, p. 8-11.

Claims (2)

1. METHOD FOR PRODUCING HIGH-OCTANE GASOLINE AND AROMATIC HYDROCARBONS, including catalytic reforming of straight-run gasoline fractions, isolation by distillation of the intermediate benzene-containing fraction from liquid products of reforming of a wide fraction, isolation by extraction or extractive distillation of non-aromatic hydrocarbons with the formation of that reforming is subjected to separately wide and narrow fractions containing predominantly enno hydrocarbons C ₇ - C ₁₀ and C ₆ - C _7, respectively, benzene-containing fraction 20 - 50% isohexane hydrocarbons from their potential content in liquid reformate is subjected to additional co-processing with the gas-product stream reforming narrow fractions in the presence of a pentasil-and / or an erionite-containing catalyst at a reforming pressure of a narrow fraction, a temperature of 250 - 460 ^o C and a ratio of hydrogen-containing gas to raw materials of 700 - 2000 nm ³ / m ³ , aromatic hydrocarbons are isolated from the product of joint processing and the product obtained after isolation is partially or completely directed to the offset.  2. The method according to p. 1, characterized in that a benzene-containing fraction containing 10 to 250% of toluene from its potential content in a liquid product is isolated.

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