RU2268251C1 - Method for preparing component of gasoline - Google Patents

Abstract

FIELD: petroleum chemistry, chemical technology, gasoline.

SUBSTANCE: method involves fractionating the stable reforming catalyst with isolation of light-boiling benzene-containing fraction followed by its contact with propylene-containing fraction in reactor with stirring in the presence of depleted sulfuric acid formed as a by-side product in the alkylation reaction of isoparaffins at temperature 10-20°C, in the mole ratio benzene : propylene = 1:0.20-1, and the volume ratio depleted alkylation acid : hydrocarbons = 1.0:(0.5-1.5), contact time 5-10 min followed by separation of acid from the prepared product, neutralization, washing out the formed fraction of products after interaction of benzene with propylene and its mixing with high-octane vat fraction of the stable reforming catalyst. Invention provides reducing content of benzene in the stable reforming catalyst fractions being without reducing the octane number value.

EFFECT: improved preparing method.

1 tbl, 1 dwg, 21 ex

Description

The invention relates to methods for producing components of environmentally friendly gasoline and can be used in the refining and petrochemical industries.

Recently, there has been a tendency to decrease the benzene content in motor gasolines, which should not exceed 1% (vol.). At the same time, the average benzene content in gasolines produced in the Russian Federation is 2.7%, and in high-octane gasolines - up to 7%. A decrease in the benzene content in motor gasolines can be achieved by removing the benzene fractions from the reforming feedstock, isolating the benzene fraction from the reformates and further processing it (for example, selective hydrogenation of benzene), and extracting benzene with selective solvents.

Known [Lipovich V.G., Polubentseva M.F. Alkylation of aromatic hydrocarbons. - M.: Chemistry, 1985. - 272 p.: Albright L.F. - In the book: Alkylation. Research and industrial design process. Per. from English M., Chemistry, 1982] methods for processing benzene by alkylating it with lower olefins (most often propylene) to form isopropylbenzene and other alkyl aromatic hydrocarbons. Also known [Oil, gas and petrochemicals abroad, 1993, No. 6, p. 87] is a method for reducing the concentration of benzene in a light gasoline fraction by alkylating benzene with propylene using solid phase catalysts.

A disadvantage of the known methods is the complexity of the hardware design, harsh conditions (7-14 MPa), low (50-60%) conversion of benzene, the use of expensive zeolite and unstable (based on aluminum chloride) catalysts.

The closest solution in technical essence and the achieved results is the method [RF patent No. 2194740, class 7 C 10 G, C 07 C 15/06, publ. December 20, 2002] the removal of benzene from gasoline components by fractionation of stable catalysis with the release of a boiling benzene-containing fraction, which is subjected to extraction to obtain benzene and toluene.

The disadvantage of the method adopted for the prototype is the reduction in the octane number of stable catalysis as a result of the removal of part of aromatic hydrocarbons.

The aim of the invention is to reduce the benzene content in the fractions of stable reforming catalysts without reducing the octane value.

This goal is achieved by the method according to which a low-boiling benzene-containing reforming fraction is contacted with a propylene-containing fraction in a reactor with stirring with spent sulfuric acid, formed as a by-product in the alkylation of isoparaffins with olefins, at a temperature of 10-20 ° C, the benzene: propylene molar ratio 1: 0 , 20-1, a volume ratio of spent alkylation acid: hydrocarbons 1: 0.5-1.5, contact time 5-10 minutes, followed by separation of acid from the resulting product, neutralization washing the resulting fraction of the reaction products of the interaction of benzene with propylene and mixing it with the high-octane bottoms fraction of stable reforming catalysis.

An essential distinguishing feature of the proposed method for reducing the concentration of benzene compared to the method adopted for the prototype is the use of sulfuric acid olefins used in the process of sulfuric acid alkylation of isoparaffins with olefins as a catalyst for alkylating benzene.

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

Analysis of the known technical solutions for the alkylation of isoparaffins with olefins allows us to conclude that they lack features similar to the essential distinguishing features of the claimed method, that is, the compliance of the proposed method with the requirements of an inventive step.

The method is as follows. The low-boiling benzene-containing fraction (fr.n.c - 85 ° C of stable reforming catalyst or benzene) is sent to the stirred reactor, where benzene is contacted with a propylene-containing fraction with a propylene content of at least 70 vol.% And the spent sulfuric acid formed in as a by-product in the alkylation of isoparaffins with olefins. Alkylation conditions: temperature 10-20 ° С, molar ratio benzene: propylene 1: 0.20-1, volume ratio spent alkylation acid: hydrocarbons 1: 0.5-1.5, contact time 5-10 minutes.

An emulsion of sulfuric acid and alkylation products from the reactor enters the sump, where it is stratified into sulfuric acid and the hydrocarbon phase. After alkaline and aqueous washing, the reaction products are sent for stabilization, after which they are mixed with a high octane bottoms fraction of stable reforming catalysis.

The advantages of the proposed method are illustrated by the following examples.

Example 1

A wide fraction of unstable reforming catalysis enters the distillation column, where it is divided into two fractions - light NK - 85 ° C (benzene content of 9.1 wt.%) And heavy 85 ° C - since The light benzene-containing fraction is sent to an alkylation reactor with a propeller stirrer, where the benzene is alkylated with propylene in a molar ratio of propylene: benzene equal to 1: 1.

The propane-propylene fraction (PPF) was fed into the liquid reagents (the catalyst was spent sulfuric acid from a 25/7 alkylation unit with a monohydrate concentration of 90.1 wt.% And an organic content of 2.92 wt.% And a light benzene-containing fraction) in the reactor. ) from the installation for the production of MTBE (content, vol.%: propylene 75, propane 23, ethane up to 2).

Alkylation conditions: temperature 20 ° С, pressure 0.5 MPa, contact time 4 min., Volume ratio spent sulfuric acid: hydrocarbons 1.0: 1.0. The residual concentration of benzene is 0.4 wt.% (Benzene conversion of 95.5%).

An emulsion of sulfuric acid and alkylation products from the reactor enters the sump, where it is stratified into sulfuric acid and the hydrocarbon phase. Sulfuric acid from the bottom of the sump enters the reactor. The process is carried out at a concentration of sulfuric acid not lower than 85 wt.%. The concentration of sulfuric acid was maintained by continuously pumping fresh spent sulfuric acid into the reactor and removing its balance amount from the sump. The reaction products from the sump after alkaline and water washing was directed to stabilization.

When mixing the alkylated fraction NK-85 ° C with the heavy fraction of stable catalysis 85 ° C - K. there was only a slight (by 5 ° C) weighting T c.k. catalyzate, while OCh m.m. total gasoline increased from 82.8 to 84.2 points.

Example 2

The light benzene-containing fraction was subjected to alkylation according to example 1 with a molar ratio of propylene: benzene equal to 1: 0.6. The alkylation conditions and the results are shown in table 1.

Examples 3-7. Stable catalyzate from the L-35/6 reforming unit was subjected to extraction (solvent - triethylene glycol, solvent: stable catalysis ratio 7: 1, temperature 150 ° С) to obtain benzene (concentration 99.98 wt.%, Crystallization temperature 5.4 ° С )

Alkylation of benzene was carried out according to example 1 with a contact time of 3-20 minutes. After separation of the unreacted PPF, a mixture of IPB, diisopropylbenzene (DIPB) and spent sulfuric acid with a concentration below 85 wt.% Was formed. After stopping the stirrer, the products were separated into acid and hydrocarbon layers. The latter was washed with a 3% NaOH solution, then with water until neutral. The alkylation conditions and the results are shown in table 1.

Examples 8-12.

Alkylation of benzene was carried out according to example 2 at an alkylation temperature of 5-40 ° C. The alkylation conditions and the results are shown in table 1.

Examples 13-15.

Alkylation of benzene was carried out according to example 2 with an acid / hydrocarbon ratio of 0.5: 1.5. The alkylation conditions and the results are shown in table 1.

Examples 16-20.

Alkylation of benzene was carried out according to example 2 with a molar ratio of benzene / propylene (1: 0.20) - (1: 0.80). The alkylation conditions and the results are shown in table 1.

Example 21 (comparative)

A wide fraction of NK - 200 ° C of stable catalyzate from the LG-35 / 11-300 reforming unit (aromatic hydrocarbon content 59.6 wt.%, OHM m. 82.8 points) were subjected to fractionation into two fractions - light NK - 85 ° C (content, wt.%: Benzene 9.1, toluene 2.0) and heavy 85 ° C - K. The yields of fractions 24.2 and 75.8 wt.%.

The light benzene-containing fraction was extracted (solvent - triethylene glycol, solvent / stable catalysis ratio 7: 1, temperature 150 ° C) to obtain a mixture of benzene and toluene (10.9 wt.% For stable catalysis) and raffinate (13.3 wt. % on stable catalysis). After mixing the heavy fraction of 85 ° C. with a raffinate, a component of gasolines with an OCh m.m is obtained 78.8 points.

As can be seen from table 1, with a contact time of less than 5 minutes (example 3), the conversion of benzene is low, and with a contact time of more than 10 minutes (example 6-7), the selectivity of the process decreases (the DIPB content increases above 30%), which is undesirable since this the component has a high boiling point for use in commercial gasolines. At an alkylation temperature below 10 ° C (example 8), the low conversion of benzene (37.9 wt.%), And above 20 ° C (examples 11-12), the content of IPB in the product varies slightly. In that case, if the light gasoline fraction is not subjected to alkylation (example 21 according to the prototype) after the isolation of benzene, the OP value falls by 4 points.

Table 1. Example No. Reaction conditions The composition of the products, wt.% The conversion of benzene,% Temperature ° C Contact time, min The molar ratio of benzene: propylene The ratio of acid: hydrocarbons Benzene IPB DIPB one twenty four 1: 1 one 0.4 5,0 3.4 95.5 2 twenty four 1: 0.6 one 3.3 3.0 2.7 63.3 3 7 3 1: 1,1 one 80.1 19.0 0.9 19.9 four 7 5 " one 62.1 34.8 3,1 37.9 5 7 10 " one 28.9 57.6 13.5 71.1 6 7 fifteen " one 7.6 61.7 30.7 92.4 7 7 twenty " one 2,8 52.8 44,4 97.2 8 5 5 1: 0.4 one 96.6 2,8 0.6 3.4 9 7 5 " one 94.3 4,5 1,2 5.7 10 10 5 " one 69.3 25.8 4.9 30.7 eleven twenty 5 " one 64,4 29.9 5.7 35.6 12 40 5 " one 54.8 35.6 9.6 45,2 13 twenty 5 1: 0.4 0.5 65.9 28.8 5.3 34.1 fourteen twenty 5 " 1,0 65,2 29.6 5.2 34.8 fifteen twenty 5 " 1,5 65.3 29.3 5,4 34.7 16 twenty 5 1: 0.20 one 72.5 25.3 2.0 27.5 17 twenty 5 1: 0.40 one 65.8 28.9 5.3 34.2 eighteen twenty 5 1: 0.50 one 54.5 31.7 7.3 45.5 19 twenty 5 1: 0.65 one 30,4 46,4 18.6 69.6 twenty twenty 5 1: 0.80 one 17.6 46.5 27.7 82,4 * raw material - fraction n.c.-85 ° C of stable catalysis of the catalytic reforming unit LG-35 / 11-300

Claims (1)

A method of obtaining a component of gasoline with a low benzene content by fractionation of a stable reforming catalysis with the separation of a low boiling benzene fraction, characterized in that the low boiling benzene fraction is contacted with a propylene fraction in a stirred reactor with spent sulfuric acid formed as a by-product in the case of alkylation with isofe temperature 10-20 ° С, molar ratio benzene: propylene 1: 0.20-1, volume ratio spent acid from alkylation: hydrocarbons 1: 0.5-1.5, contact time 5-10 min, followed by separation of the acid from the resulting product, neutralization, washing of the resulting fraction of the products of the interaction of benzene with propylene and its mixing with high-octane bottoms fraction of stable reforming catalyst.