SU998453A1 - Method for two-stage purification of aromatic hydrocarbons - Google Patents

Description

The invention relates to methods for purifying aromatic hydrocarbons of petroleum, low chemical and coke chemical origin from non-aromatic impurities and can be used in the petroleum refining, petrochemical, oil shale and coking chemical industries.

Known two-step methods for the purification of aromatic hydrocarbons from impurities of non-aromatic hydrocarbons. At the first stage, the raw materials are purified from diene hydrocarbons that are prone to polymerization, and at the second stage, hydrocracking of sulfur compounds and saturated hydrocarbons to compounds with a lower molecular weight, which can be easily removed by subsequent distillation.

Known two-step method for the purification of aromatic hydrocarbons

 from non-aromatic impurities using an aluminobaltmolybdenum catalyst at the first stage, and alyumochromic catalyst at the second stage.

Vo rolled the torus. In the first-stage reactor, they support 220–25 (f.S. second stage conditions: € 580-620, pressure

50-60 kgf / cMi, bulk feed rate of 0.5.

The closest to the invention of the technical essence and the achieved result is a method of two-stage purification of aromatic hydrocarbons from unsaturated hydrocarbons and sulfur compounds with the separation of unsaturated, at the first stage,

to hydrocarbons at elevated temperatures and pressures, in the presence of a catalyst containing aluminum, at the second stage - from sulfur compounds at temperatures above and below.

15 pressure in the presence of hydrogen and a catalyst containing alumina.

According to the well-known method, in the first stage, the fraction of aromatic

20 hydrocarbons are purified from unsaturated compounds using as a catalyst palls in the sulphide form on alumina containing 6.5–5.0 wt.% Potassium oxide,

25 at 150-250 С, pressure 30-60 kgf / cm in the presence of hydrogen-containing gas. At the second stage, aromatic hydrocarbons are purified from sulfurous and 1 saturated hydrocarbons on aluminum-

thirty . Baltmolybdenum catalyst at 550-58 (US, pressure 30-50 kgf / cm and raw material space velocity 0.5 h. The degree of purification of raw benzene from n-heptane (the most difficult impurity is 63.0 - 78 rel.%) The method of purification of aromatic hydrocarbons from non-aromatic impurities is not high enough, as well as low efficiency of the process due to the use of expensive palladium catalyst in the first stage of purification, as well as low productivity and high operating temperature. The second step of the purification stage, the purpose of the invention is to increase the degree of purification of aromatic hydrocarbons. the presence of natural montmorillonite-Palygorsky goods of clay, additionally containing 0.1-10 wt.% aluminum sulphate, followed by separation of the polymers formed by distillation at atmospheric pressure and feed to the second stage for the separation of sulfur compounds, which are carried out at 450-520 ° C, pressure 16-50 kg / cm in the presence of hydrogen using a catalyst containing molybdenum oxide, boron oxide, mordenite, alumina, with the following ratio components,% by weight: 5-13 Molybdenum oxide 1-15 Boron oxide 5-40 Mordenite Rest Alumina The method is carried out as follows. . The fraction of aromatic hydrocarbons is directed to the first purification stage, the adsorption-catalytic one. The cleaning is carried out on the adsorbent of the natural clay of the montmorillonite-palygorskite structure, modified with aluminum sulphate, at 150-230 ° С, pressure 16-20 kgf / cm and raw space velocity of 0.51, 5. Then the fraction of aromatic hydrocarbons is sent for rectification to remove the polymer compounds formed during adsorption-catalytic purification. After rectification, the fraction of aromatic hydrocarbons is directed to the second purification stage (hydrotreatment / zeolite catalyst). Hydrotreating is carried out at 450–520 ° C pressure 10–50 kgf / cm, the feed feed scattering ratio is 0.5–3 times gas 1000 - 2000 v / v, raw materials. PRI-MER 1. Fraction of aromatic hydrocarbons of pyrolysis products, composition, wt.%: benzene 39.73, toluene 59.54; aromatic C 0.01 / non-aromatic 0, 73, including, n-heptane, 0.0807, methylcyclohexane, 0.049j cyclohexane, 0.0038, thiophene, 0.435, methylthiophene, 0.0149; diolefi New 0.061 and olefinic 0.050, sent to the first stage of purification in an adsorber with a diameter of 25 mm, loaded with 100 ml of the adsorbent composition, wt.%: aluminum sulphate 0.5, clay montmorillonite-pleygorskite structure the rest. 150 ° C, a pressure of 20 kgf / cm and a bulk feed rate of 0.5 hours. The product from the adsorber is sent for rectification into a 19 mm diameter column filled with a Levin nozzle, with 18 theoretical plates. Distillation reclamation: raw material consumption 60 ml / h, pressure 0.4 kgf / cm, column-top temperature 94C, bottom column temperature, reflux ratio O, 2. The selection of aromatic hydrocarbons is 99%. The fraction of aromatic hydrocarbons after the first stage of purification and rectification is directed to the second stage of purification - Hydrotreating - to the reactor. flow type, loaded with 100 g of catalyst composition, wt.%: molybdenum oxide 5.0; boron oxide l, 0i mordenite 5.0 and alumina the rest. Conditions for cleaning at the second stage: temperature 480 ° C, pressure 10 kgf / cm, bulk feed rate 1 and circulation rate of hydrogen-containing gas (70 vol.% H) 2000 nl / l feed per hour. Example 2. The purification of the fraction of aromatic hydrocarbons of the composition indicated in example 1 is carried out analogously to example 1. The composition of the adsorbent, wt%: aluminum sulphate 5.0; clay montmorillonite-plygorskite structure the rest. Conditions of adsorption-catalytic purification: temperature 230 ° C, pressure 16 kgf / cm and bulk feed rate of 1, 5 hours. The selection of aromatic hydrocarbons is 99.10%. Conditions of rectification are similar to example 1. The composition of the hydrotreating catalyst, wt.%: Molybdenum oxide 10.0; boron oxide 3.0; mordenite 15.0 and alumina: mini else. Hydrotreating conditions: temperature 480C, pressure 30 kgf / cm, volumetric feed CKOJxscTi 0.5 h — and the circulation ratio of hydrogen-containing gas (70% 0 (5.% C) 1000 nl / l feed per hour, P r and 3. Purification of the fraction of aromatic hydrocarbons of the composition specified in Example 1, wire. Same as Example 1. Composition of the adsorbent wt.%: Aluminum sulphate 10.0 montmorillonite-palygorskite clay structurally the rest. Condition Adsorbent-Dona-catalytic purification: temperature, pressure 18 kgf / cm -, the volume of raw materials feed supply 1.0. Conditions of rectification are similar. Example 1. The selection of aromatic hydrocarbons is 99.15%. The composition of the hydrotreating catalyst, wt.%: molybdenum oxide 13.0, boron oxide 5.0, mordenite 30.0 and alumina else. Hydrotreating conditions: temperature, pressure 30 kgf / cm, the feed rate of the raw material 1 and the circulation ratio of the hydrogen-containing gas (70% by volume H) is 1500 nl / l of raw material per hour. Example 4. The purification of the aromatic hydrocarbon fraction of the composition specified in example 1 is carried out analogously to the example 1. The first stage of purification is carried out on the adsorbent and under the conditions specified in Example 2. Sec. The aromatic hydrocarbon ratio is 99.0%. Conditions of rectification: column top temperature, bottom temperature, reflux number 0.3. The composition of the hydrotreating catalyst, wt.%:. Molybdenum oxide 10.0; boron oxide 10.0) mordenite 40.0 and alumina else. Hydrotreating conditions: temperature, pressure 30 kgf / cm, volume l, feed rate 1 h and feed rate of hydrogen-containing gas (70 vol.% H) 1500 nl / l feed per hour. Example 5. Purification of the fraction of aromatic hydrocarbons of the composition specified in Example 1 is carried out according to Example 1. Adsorption-catalytic purification is carried out on an adsorbent and under the conditions of Example 2, the selection of aromatic hydrocarbons is 99.0%. . The conditions of rectification are the temperature of the top of the column, the temperature of the bottom of the column, the reflux number 0.3. The composition of the catalyst Hydrb cleaning,. Mas.%: Molybdenum oxide orOlOl boron oxide 5.0; mordenite 15, O and okvs sshyumini else .; Hydrotreating conditions: temperature, pressure 50 kgf / cm; raw material feed rate 3.0; hydrogen-containing circulation ratio: gas (70 vol.%) ISOO nl / l; in an hour .. Example. To compare the proposed method of purification of aromatic hydrocarbons with the lime hydrocarbon fraction of the composition 4-4 in Example 1, the first hydrotreating step was sent to a flow type reactor loaded with 100 g of catalyst, composition,% by weight: palladium 0.5; potassium oxide 1.5 and alumina rest., Cleaning conditions: temperature pressure 30 kgf / cm feedstock feed rate 1.5 h and circulation ratio of water-containing gas (70% by volume of H 2 1500 nl / l feedstock per hour. They are fed to the second stage of purification into a flow type reactor loaded with 100 g of a aluminum – cobalt or libdenic catalyst composition, in wt.%: cobalt oxide 4.1} molybdenum oxide 11.0 and alumina else. g Cleaning condition at the second stage: temperature, pressure 30 kgf / cm, raw material feed rate 0.5 h. circulation rate and hydrogen containing gas (70 vol.% 1) 1500 nl / l of feed per hour. Experimental conditions and composition of aromatic hydrocarbons in examples 1-6 are presented in Table 1.

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EXAMPLE 7: Purification of the fraction of aromatic hydrocarbons of coke-chemical origin of the composition,.% T benzene 84.52; toluene 13.93; xylenes 0.108) n-heptai, methylcyclohecoane 0.105; cyclohecran O 1Q2, thiophene 0.846, methylthiophy 0.101 diene 0.110 and rlefin 0.090, are carried out in a manner similar to Example 1. The first purification step is carried out on an adsorbent under the conditions indicated in Example 2.

Conditions of rectification the temperature of the top of the column, bottom -

Benaol

Toluene

Xylenes

n-heptane

Methylcyclogea

Cyclohexane

Diene

Olefinic

Thiophene

Methylthiophene

P p 8. fraction of aromatic carbohydrates, products pyro-. Lysis composition, wt.%: & Enzene 43.95, toluene 48.35, aromatic with 2.5; 50 non-aromatic 5.2; including n-goptane O, 58J Methylcyclohexane 0.45; cyclohexane 0.38; tirfen 0,28; methylthiophene 0.01 diolefinic 0.98 and olefinic 0.85 are sent to the adsorbent-adsorber with a diameter of 25 mm, loaded with 100 ml of the adsorbent composition, wt.%: aluminum sulphate 0.5; clay montmorillonite-palygskitovoy struktu- ". ry the rest.

Cleaning conditions: temperature, pressure of 20 kgf / cm and volumetric feed rate of 0.5. Cleared;

reflux ratio of 0.25. The selection of ape; tical hydrocarbons was 99.1% in s. The composition of the catalyst is hydro. purification, wt.%: molybdenum oxide 10, boron oxide 15, o; mordenite 40.0 and. alumina else ..

Hydrotreating conditions; temperature, pressure of 30 kgf / cm, bulk feed rate 1 and circulation rate of hydrogen. gas C70 o6.% H5i) 1500 nl / l mr per hour. The composition of the resulting hydrogenation is shown in table 2.

Table. 2

86.72

9,435

3,821

0,007

0,0085

0,008

0.0001 0.00002

The nasal fraction is sent for rectification, which is carried out under the conditions of Example 1. The selection of aromatic hydrocarbons is 99.0%. Then the fraction of aromatic hydrocarbons is sent for hydrotreatment into a flow type reactor loaded with 100 g of catalyst composition, wt.% Chase molybdenum 2, o; boron oxide 5.0 / mordenite 70.0 n the rest of alcmini oxide.

The conditions of the HYDRAULIC CLEANING temperature, pressure 30 KTc / cf, raw material feed rate of 1 h, circulation rate of hydrogen-containing gas 1500 nl / l of raw material per hour. The compositions of the products after adsorption-catalytic purification, rectification and hydrotreating are given in table. 3

As follows from examples 1-8, the invention allows to increase the degree of purification of aromatic hydrocarbons from non-aromatic impurities. Thus, the adsorption-catalytic purification compared to hydrotreating on a palladium catalyst allows, with the same degree of purification from diene hydrocarbons, 100%. t 65

Table 3

Claims (2)

reduce the content of methylcyclohexane and cyclohexane in the product after the first stage to 0.050 and 0.0038% by weight, respectively, against 0.063 and 0.016% by weight ... (Table 1). This creates more favorable conditions for the purification of aromatic hydrocarbons in the second stage. More. the high content of cyclohexane and vi & tylcyclohexane in the product after the first stage is known by comparison with the raw material with the partial hydrogenation of aromatic hydrocarbons to naphthenic. The use of an olitiferous catalyst in the second stage allows a significant increase in the degree of purification of aromatic hydrocarbons from thiophene, n-heptane, methylcyclohexane, and cyclohexane. So, according to the proposed method, the residual content of the most undesirable impurity (n-heptane) can be increased to 0.0080, 003% wt.% Versus 0.018 may.% By; well-known method. In the first case, it is from this and that :;. 96.3% degree of purification of aromatic: H- "hydrogen of hydrogen from n-heptane, which is by doj 20 relative% more than by a known method. Moreover, these results dorigate at a second-stage purification temperature on TO-IOO C lower and at a space velocity that is more than double than with the known method .. I, -. The efficiency of the proposed method increases due to the fact that on the zeolite-containing catalyst, besides purification of aromatic hydrocarbons from non-aromatic impurities, disproportionation of toluene is carried out, which also causes an increase in the yield of the most valuable product, benzene. Thus, in examples 1-5, the yield of benzene is 4146 wt.% Versus 35.96 wt.% In the known method and 39.77 wt.% In the starting 1 raw material. The invention The method is a two-step purification of aromatic hydrocarbons from non-ferrous hydrocarbons and sulfur compounds with separation of unsaturated hydrocarbons at the first stage at elevated temperature and pressure in the presence of a catalyst containing aluminum, at the second stage sulfur compounds at elevated temperature and pressure in the presence of hydrogen and alumina-containing catalyst, molybdenum oxide, characterized in that, in order to increase the degree of purification, the purification in the first stage is carried out at 150-230С, pressure of 16–20 kg / cm in the presence of natural montmorillonite-plygorkite clay, additionally containing aluminum sulphate, with the end of the trunk; the separation of the formed polymers6v-ia ffth ace.y at atmospheric pressure and flow to the second -. The cleaning step, which is carried out at 450-520 ° C, pressure kg / cm in the presence of a catalyst, additionally containing boron oxide and mordenite, in the following ratio of components, may.%: Molybdenum oxide 5-13 Boron oxide 1-15 Mordenite5 -70 Alomino oxide Else Sources of information taken into account in the examination 1. US patent 3178486, class 260-672 published. 1965. 2. Authors certificate of the USSR; No. 521301, cl. C 10 G 23/02, 1973 I prototype).