RU2171826C1 - Method for isolation of organosulfur compounds from petroleum and petroleum products - Google Patents

Abstract

FIELD: crude oil treatment and petroleum processing. SUBSTANCE: isolation of organosulfur compounds from kerosene and diesel fraction is effected by adsorption in centrifugal field by common rotation of pure adsorbent and initial oil stock in rotor for 30-40 min, amounts of adsorbent and oil stock being at ratio (1.5-2.0):1 and rotor speed being within a range of 2000-2500 rpm. Method allows operations of modifying and impregnating adsorbents to be avoided, short-supply and environmentally dangerous reagents are unnecessary, consumption of adsorbent is 6-10-fold lower, and degree of removal of impurities is raised by 2.5-3 times. EFFECT: enhanced process efficiency. 1 dwg, 2 tbl, 8 ex

Description

 The invention relates to methods for the separation of organosulfur compounds of oil from petroleum products, in particular adsorption, and can be used in the refining and petrochemical industries.

 Known adsorption methods for the separation of organo-sulfur compounds of oil (CCH) from oil products - kerosene, diesel fractions, light oils based on liquid chromatography by passing the initial oil product through a fixed adsorbent layer installed in the column. Pure silica gel, alumina, activated carbon, gypsum, and mixtures thereof are used as adsorbent (Chemistry of Organosulfur Compounds Contained in Oils and Petroleum Products, Moscow: Publishing House of the USSR Academy of Sciences, 1959, 126-137; High-Molecular Oil Compounds, C. P. Sergienko, Moscow: GOSTOPTEHIZDAT, 1959, p. 247 - 292).

 However, these methods achieve a small degree of purification of petroleum products from sulfur - only 30 - 35% of the total amount of sulfur present in the feedstock. This is due to the fact that the method of liquid chromatography using pure adsorbents does not allow to separate sulfur compounds free from aromatic hydrocarbons. The combined release of sulfur compounds and aromatic hydrocarbons is associated with the proximity of their adsorption affinity with respect to the adsorbents used and is due to the similarity of the structure of CCH and aromatic hydrocarbons. In addition, the disadvantages include: 1) high consumption of eluents both quantitatively (take 4–5 times more than the original oil product) and qualitatively (take 3-4 eluents with different eluting abilities); 2) a large consumption of adsorbent, the amount of which exceeds the amount of the original oil by 15 to 20 times.

Known methods for the separation of CCH from petroleum products boiling in the temperature range 150 - 370 ^o C, using liquid chromatography on silica gel and alumina with increased selectivity to organo-sulfur compounds. Increasing the selectivity allowed increasing the degree of purification of petroleum products from CCH to 70% of the total sulfur content. An increase in the degree of isolation of CCH from petroleum products is achieved by modifying and impregnating silica gel and aluminum oxide with mercury acetate, silver nitrate, palladium chloride, zinc chloride, tin tetrachloride. The application of these methods in industry is almost impossible due to: 1) the use of expensive, scarce, toxic and environmentally hazardous chemicals; 2) the negative impact of these substances on the quality of the petroleum products themselves; 3) low-tech operations for the preparation of adsorbents and chromatographic columns. (A. S. USSR 1340422, C 10 G 29/06, 01/29/87; RF Patent 2083640, C 10 G 25/00, 07/10/97).

 Closest to the proposed invention relates to a method for the isolation of CCH from petroleum products, in particular from kerosene, using liquid chromatography using an adsorbent modified with dimethylformamide, which is a mixture of activated carbon and bleaching clay (AS USSR N 419545, C 10 G 25 / 00, 03/15/74).

 Isolation is carried out at room temperature in a glass percolator with an adsorbent column height of 300 mm. The amount of the initial fraction (kerosene) is taken to the amount of the mixture of adsorbents in a ratio of 1: 1. This amount of kerosene is passed by gravity through a fixed bed of adsorbent modified with up to 10% dimethylformamide. As a result of the technological operation, an adsorbate is obtained in an amount of 80 - 82 wt.% And with a residual sulfur content of from 0.05 to 0.2 wt.% As well as a sera aromatic concentrate in an amount of 15 - 17 wt.% And with a sulfur content of 6.0 - 8.5 wt.%, Which is the degree of release of total sulfur 70 - 90%.

 This method is also ineffective. First, an expensive and scarce chemical is used to modify the adsorbents. Secondly, dimethylformamide has a negative effect on the quality of the adsorbent. Thirdly, for the repeated use of adsorbents, they must again be modified.

 The present invention solves the problem of increasing the degree of separation of CCH from petroleum products — kerosene and diesel oil fractions — by pure adsorbents and increasing the efficiency of the separation method.

 The tasks are solved in that the adsorption process for the separation of CCH from kerosene and diesel fractions is carried out in a centrifugal field, by joint rotation of the pure adsorbent and the original oil in the rotor, while the amount of adsorbent and the amount of oil are taken in the ratio (1.5 - 2.0) : 1, and the rotation of the rotor is set within 2000 - 2500 rpm./min for 30 to 40 minutes.

 The above distinguishing features in the proposed method help to increase the degree of isolation of CCH from the kerosene and diesel oil fractions with pure adsorbents - silica gels and aluminum oxide - up to 88 - 93 wt.%.

The experiments showed that such a percentage of excretion occurs as a result of the fact that:
1 - a centrifugal field contributes to an increase in the adsorption affinity of CCH for silica gel and alumina, and this increase is greater than an increase in adsorption affinity for aromatic hydrocarbons;
2 - the optimal difference (gradient) of the adsorption affinity for CCH and aromatic hydrocarbons, which ensures the maximum separation of CCH from these petroleum products, is achieved by rotating the rotor 2000 - 2500 rpm / min (when the rotor rotates less than 2000 rpm / min - 65%, and when rotating more than 2500 rpm./min the degree of isolation of CCH increases by only 1 - 2%);
3 - the time during which the maximum allocation of CCH is achieved when the rotor rotates 2000–2,500 rpm is 30–40 min (an increase in the time of rotation of the rotor does not increase the degree of CCH isolation from petroleum products);
4 - the quantitative ratio of the adsorbent and the initial oil product equal to (1.5 - 2): 1, calculated and taken into account the adsorption capacities of adsorbents - for silica gel, the sorption capacity is 1/5 - 1/6, and for alumina - 1/7 -1/8.

 The proposed method for the isolation of CCH from kerosene and diesel fractions by adsorption on pure silica gel and alumina in a centrifugal field is implemented in a rotary apparatus. The drawing shows a diagram of a rotary apparatus, consisting of: 1 - a rotor with a cylindrical section and an internal grid (for filling the adsorbent); 2 - a truncated conical bottom for receiving oil during the filling and receiving adsorbate after the end of the separation process; 3 - a flat cover with a loading hole; 4 - electric wires; 5 - rotor speed controller; 6 - a protective casing; 7 - boot device; 8 - valves for draining the adsorbate from the conical bottom 2. The dimensions of the rotor were calculated so that it could be loaded into the cylindrical section of the rotor 1 of the adsorbent in an amount of 600 g, and pour up to 450 g of the initial oil product into the truncated conical bottom 2.

 The initial oil products are kerosene and diesel fractions of the direct distillation of Arlan and Surgut oils.

 Table 1 presents the main physical and chemical indicators of petroleum products. Silica gel of the ASK brand, large-pore and with a sorption capacity of 1/5 - 1/6, and aluminum oxide of the K-6 brand with a sorption capacity of 1/7 - 1/8 are taken as adsorbents. The conditions of the experiment on the proposed method for the isolation of CCH by pure adsorbents in a centrifugal field are presented in examples 1 to 8, and the experimental results and analysis results are shown in table 2.

 Example 1. The kerosene fraction of Arlan oil, the amount of 400 g, the total sulfur content of 1.42 wt.%. The adsorbent is ASK grade silica gel, amount 600 g. Silica gel is loaded into the cylindrical section of rotor 1, cover the rotor 1 with a cover, install a protective casing 6, turn on the electric drive 4 and set the initial rotor speed equal to 800 - 1000 rpm by the rotation speed regulator 5. Then from the loading device 7, kerosene is poured into the rotor. After the filling of kerosene, the rotational speed of the rotor 1 is raised to 2000 - 2500 rpm. / min These revolutions are kept for 30 to 40 minutes. Then, the electric drive 4 is turned off. In the process of slowing down the rotation of the rotor 1, the resulting adsorbate flows into the conical bottom 2. After stopping the rotor 1, another 10-15 minutes are set to drain the adsorbate from the contact zone with silica gel to the conical bottom 2. The adsorbate is drained from the conical bottom 2 through the drain valve 8. Silica gel with adsorbed concentrate from the CCH is discharged from the cylindrical section, loaded into the column for liquid chromatography and elution, the CCH concentrate is removed from silica gel. The results and analysis results for density, refractive index, sulfur content in the adsorbate and concentrate are presented in table 2.

 Example 2. Kerosene fraction of Surgut oil, the amount of 400 g, the total sulfur content of 1.12 wt.%. The adsorbent is ASK grade silica gel, amount 600 g. The isolation of CCH is carried out analogously to example 1. The results obtained and the results of the analyzes are presented in table 2.

 Example 3. The diesel fraction of Arlan oil, the amount of 400 g, the total sulfur content of 2.04 wt.%. The adsorbent is ASK grade silica gel, amount 600 g. The isolation of CCH is carried out analogously to example 1. The results obtained and the results of the analyzes are presented in table 2.

 Example 4. The diesel fraction of Surgut oil, the amount of 400 g, the total sulfur content of 1.68 wt.%. The adsorbent is ASK grade silica gel, amount 600 g. The isolation of CCH is carried out analogously to example 1. The results obtained and the results of the analyzes are presented in table 2.

 Example 5. The kerosene fraction of Arlan oil, the amount of 400 g, the total sulfur content of 1.42 wt.%. The adsorbent is aluminum oxide grade K-6, the amount of 600 g. The isolation of the CCH is carried out analogously to example 1. The results obtained and the results of the analyzes are presented in table 2.

 Example 6. Kerosene fraction of Surgut oil, the amount of 400 g, the total sulfur content of 1.12 wt.%. The adsorbent is aluminum oxide grade K-6, the amount of 600 g. The isolation of the CCH is carried out analogously to example 1. The results obtained and the results of the analyzes are presented in table 2.

 Example 7. The diesel fraction of Arlan oil, the amount of 400 g, the total sulfur content of 2.04 wt.%. The adsorbent is aluminum oxide grade K-6, the amount of 600 g. The isolation of the CCH is carried out analogously to example 1. The results obtained and the results of the analyzes are presented in table 2.

 Example 8. The diesel fraction of Surgut oil, the amount of 400 g, the total sulfur content of 1.68 wt.%. The adsorbent is aluminum oxide grade K-6, the amount of 600 g. The isolation of the CCH is carried out analogously to example 1. The obtained analysis results are presented in table 2.

 As can be seen from table 2, the degree of isolation of CCH by pure adsorbents - silica gel and aluminum oxide - from kerosene and diesel oil fractions by the proposed method is 2.5-3.0 times higher than by known methods. In addition, the proposed method is much more efficient than the prototype and the analogues used. Efficiency is manifested in the fact that: it is not necessary to carry out the operations of modifying and impregnating adsorbents; no need to use scarce and environmentally hazardous chemicals; the amount of adsorbent must be taken 8-10 times less.

Claims (1)

 The method of separation of organo-sulfur compounds of oil from kerosene and diesel oil fractions with adsorbents, characterized in that the process is conducted in a centrifugal field by the joint rotation of the adsorbent and the initial oil product in the rotor with a mass ratio of adsorbent and oil product (1.5 - 2): 1, the number of rotor revolutions 2000 - 2500 rpm and rotor rotation time 30 - 40 min.

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