RU2135548C1 - Method of processing secondary distillates - Google Patents

Abstract

FIELD: organic chemistry. SUBSTANCE: secondary distillates evaporating at temperatures ranging from 21-205 C and/or 140-360 C in admixture with directly distilled fraction are subjected to hydropurification at elevated temperature and pressure in the presence of hydrogen in two stages using 1st and 2nd stage catalysts at 1:2-6 weight ratio. Fraction evaporating at 185 is then isolated and is subjected to catalytic reforming. Hydropurification is carried out at 200-320 C in 1st stage and at 280-380 C in 2nd stage. Either individual fraction of secondary distillates in admixture with directly distilled fraction or mixture of secondary distillates in admixture with directly distilled fraction is subjected to hydropurification at secondary distillate to directly distilled fraction ratio from 5-50 to 95-50%. EFFECT: higher degree of hydrogenation and hydrodesulfurization of secondary distillates, and quality of fuel is maintained. 4 cl, 14 ex, 2 tbl

Description

 The invention relates to methods for processing distillates of secondary origin of processes of delayed coking, thermal cracking, visbreaking, other destructive thermal processes and can be used in the oil refining industry.

A known method of purification of cracked gasoline from sulfur and unsaturated compounds by hydrogenation on an aluminum-cobalt-molybdenum catalyst at a temperature of 360 - 400 ^o C, a pressure of 30 - 50 atm in a mixture with diesel fuel or vacuum gas oil in a ratio of 3: 7. The disadvantage of this method is the low degree of hydrodesulfurization of gasoline and diesel fuel (residual sulfur content is 0.1 - 0.15 wt.% and 0.2 wt.%, respectively), high operating costs (AS USSR, N 336994, 1980).

There is also known a method of processing gasolines of thermal processes by rectification to obtain the NK-180 ^o C fraction and the residual fraction, followed by hydrotreating and reforming the NK-180 ^o C fraction. The feedstock is subjected to preliminary heat treatment at a temperature of 350 - 420 ^o C and a pressure of 4.0 - 16.0 MPa. The disadvantage of this method is the high residual content of unsaturated hydrocarbons in the NK-180 ^o C fraction - more than 8.0 wt.%, The high temperature and pressure of the preliminary heat treatment and subsequent hydrotreating of the NK-180 ^o C fraction, carried out at a temperature of 380 - 420 ^o C and pressure 3.0 - 4.0 MPa (A.S. USSR N 1444345, 1988).

The closest in technical essence and the achieved effect is a method of refining thermal cracked gasoline by hydrotreating in a mixture with straight-run diesel fuel and subsequent reforming of hydrotreated gasoline (fr. 80 - 180 ^o C) in a mixture with straight-run raw materials ("Refining and petrochemicals", - N 8, 1990, - pp. 12-16).

The known method has the following disadvantages:
- hydrotreated gasoline distillate after thermal cracking of diesel fuel has a high iodine number 15 - 44, the J _2/100 g product and a sulfur content of 0.1 -. 0.05 wt%, hydrotreated diesel fuel and has a sufficiently high sulfur content 0 , 08 - 0.20 wt.%, Which does not meet modern requirements for environmentally friendly fuel - not more than 0.05 wt.%;
- high temperature of the mixed feed hydrotreater 380 ^o C to lower the iodine number of the hydrotreated gasoline at this stage to 11 - 12, the J _2/100 g leads to an increase in net positive temperature difference in a reactor over 20 ^o C and at the outlet of the second reactor more than 400 ^o C, which is the reason for the accelerated coking of the hydrotreating catalyst, a rapid decrease in its activity and, as a result, a reduction in the inter-regeneration cycle;
- carrying out the processes of hydrogenation of unsaturated compounds and hydrodesulfurization / hydrodeazotization of the feedstock under the same conditions (high temperature and low space velocity) does not allow to achieve the required hydrogenating and hydrodesulfurization activity of the catalyst.

 The invention is aimed at solving the problem - increasing the degree of hydrogenation and hydrodesulfurization of secondary distillates while ensuring the quality of hydrotreated diesel fuel, increasing the inter-regeneration cycle of the hydrotreating catalyst, and increasing the overhaul life of the equipment.

 The solution to this problem is mediated by a new technical result, which consists in reducing the content of unsaturated hydrocarbons and sulfur in hydrotreating products while simultaneously significantly lowering the temperature of the hydrotreating process of mixed raw materials, which makes it possible to increase the proportion of secondary distillates.

 Essential features.

 Processing of distillates of secondary origin in a mixture with a straight-run fraction is carried out by hydrotreating at elevated temperature and pressure in the presence of hydrogen, followed by separation of the fraction and its catalytic reforming.

 Features.

The distillates of secondary origin are processed, boiling over in the temperature range of 21 - 205 ^o C and / or 140 - 360 ^o C, with the separation of the fraction with a boiling point of 185 ^o C and its catalytic reforming, and the hydrotreating process is carried out in two stages with intermediate heating of the gas-oil mixture at hydrotreating catalysts, for example on aluminum-cobalt-molybdenum or aluminum-nickel-molybdenum catalysts, with a mass ratio of catalysts of the first and second stages 1: 2-6, preferably hydrotreating is carried out at a temperature in the first stage of 200 - 320 ^o C and in the second stages 280 - 380 ^o C and hydrotreating is subjected to either a separate fraction of the secondary distillates (21 - 205 ^o or 140 - 360 ^o C) in a mixture with a straight-run fraction, or a mixture of secondary distillates (21 - 205 ^o and 140 - 360 ^o ) with a straight-run fraction in the ratio of secondary: straight run 5 - 50: 95 - 50%.

Example 1. The source gasoline delayed coking (fraction 21 - 205 ^o C) with quality indicators are given in table. 1 (see the end of the description) is mixed with straight-run diesel fraction 200 - 360 ^o C in a ratio of 25: 75 wt. % The resulting mixture with a sulfur content of 1.2 wt. And iodine number of 40 g J / 100 g of product is subjected to hydrotreating in two stages with intermediate heating of the gas-raw material mixture in a pilot plant with hydrogen supply in two successive reactors with autonomous electric heating of each reactor. 25 g of aluminum-nickel-molybdenum catalyst (ASM) containing 6.1% NiO, 15.3% MoO ₃ , AlO ₃ are loaded into the first reactor along the way, and 75 g of aluminum-cobalt-molybdenum (AKM) catalyst containing 3 is loaded into the second reactor along the way , 9% CoO, 14.2% MoO ₃ , AlO _{3 the} rest. The catalysts are preliminarily subjected to sulfidation in a stream of hydrogen at a pressure of 2.0 MPa and then the temperature in the first reactor is set at 280 ^° C., in the second reactor is 360 ^° C. and mixed feed is supplied. The hydrotreating process is carried out at a hydrogen pressure of 3.0 MPa, a volumetric feed rate of 3.0 hours ^-1 , the ratio of hydrogen: feed 300 nl / L. Gidrogenizat obtained is subjected to distillation with separation of the gasoline fraction NK-185 ^o C and the diesel fraction of 185 - 360 ^o C. The selected fractions to determine the sulfur content device "Sulf UV" ultraviolet fluorescence method and an iodine number according to GOST 2070-82. The sulfur content of the gasoline fraction is 0.0005 wt%, a diesel fraction -. 0.04 wt%, an iodine value of 2.0 g petrol J _2/100 g, and 0.9 g of diesel fuel J _2/100 of Diesel fuel. It meets the requirements for environmentally friendly fuels and is a commercial product. The NK-185 ^o C fraction is characterized by the following hydrocarbon composition: the content of naphthenic hydrocarbons is 34 wt.%, The content of aromatic hydrocarbons is 9.0 wt.%, The octane number according to the motor method is 54 points. The gasoline fraction is then subjected to catalytic reforming at a temperature of 500 ^o C, a pressure of 2.4 MPa, a volumetric feed rate of 1.5 h ^-1 and a hydrogen: feed ratio of 1200 nl / l. The resulting reformate has an octane rating of 85 points by the motor method and 95.5 points by the research method.

Example 2. The source gasoline delayed coking (fraction 21 - 205 ^o C) is mixed with light gas oil delayed coking (fraction 140 - 360 ^o C) in a ratio of 25: 25 wt.%. The resulting mixture of distillates of secondary origin is mixed with straight-run diesel fraction 200 - 360 ^o C in the ratio of secondary: straight-run 50: 50 wt. % and subjected to hydrotreating under the conditions of the process, as in example 1. Set other temperatures in the reactors in the first and second stages.

At a temperature of 320 ^° C in the first stage and 380 ^° C in the second stage, the sulfur content in the gasoline fraction after separation is 0.0008% (8.0 ppm), in the diesel fraction - 0.048% (480 ppm); iodine number gasoline fraction is 2.6 J g _2/100 g, diesel fraction - J, respectively, 4.0 g _2/100 g Gasoline fraction was then subjected to catalytic reforming in the conditions shown in Example 1, the octane number reformate obtained by Research method amounted to 94.0 points.

 Examples 3-4. A mixture of gasoline UZK and straight-run diesel fuel is prepared in a ratio of 5: 95 wt.%, Respectively. The conditions for the hydrotreatment process are the same as in example 1. Set other temperatures in the reactors of the first and second stages. The isolated gasoline fraction is subjected to catalytic reforming under the conditions of example 1. The octane number of the obtained reformates in examples 3 and 4 is 95.9 and 95.3 points, respectively, according to the research method (MI).

 The results are presented in table. 2.

Examples 5-6. A mixture of gas oil UZK (fraction 140 - 360 ^o C) with straight-run diesel fuel (fraction 200 - 360 ^o C) in a mass ratio of 25: 75%, respectively, is prepared. The conditions for the hydrotreatment process are the same as in example 1, except for the ratio of catalysts in the first and second stages of the hydrotreatment process, which is 1: 2 mass parts and temperature in the first and second stages of the process. The isolated gasoline fractions after hydrofining are subjected to catalytic reforming under the conditions of example 1. The octane number of the obtained reformates according to the MI is respectively according to example 5 - 93.7 and according to example 6 - 94.0 points. The results are shown in table 2.

 Example 7. The prepared mixture of secondary distillates and straight-run diesel fuel according to example 2 is subjected to hydrotreating under the conditions of examples 5, 6, but at other process temperatures in the first and second stages. The gasoline fraction is then subjected to catalytic reforming under the conditions of Example 1 — the octane number of the obtained reformate is 94.4 points in terms of MI.

 Examples 8 to 10. A mixture of gasoline ultrasonic testing and straight-run diesel fuel prepared in accordance with example 1 is subjected to hydrotreating under the conditions of example 1, but the ratio of the catalysts of the first and second stages of the process is changed, which is 1: 6 mass parts. The process temperatures in the first and second stages also vary. The isolated gasoline fractions after hydrotreatment are subjected to catalytic reforming under the conditions of example 1. The results are shown in table 2.

Example 11. The prepared mixture of example 1 is subjected to hydrotreating under the conditions of example 1, except that 75 g of aluminum-nickel-molybdenum catalyst is loaded into the second stage reactor, which is also loaded in the first stage. Thus, the ratio of the catalysts of the first and second stages is 1: 3 mass parts. The temperature in the first stage is set at 280 ^o C, in the second stage 360 ^o C. The sulfur content in the gasoline fraction is 6.8 ppm, in diesel fuel - 420 ppm; iodine number of gasoline - J 1.6 g _2/100 g, diesel fuel - 0.8 g J _2/100 Thus, the diesel fuel meets clean fuel with a sulfur content not exceeding 500 ppm. The gasoline fraction is subjected to catalytic reforming under the conditions of example 1. The octane number of the obtained reformate is 95.5 points in IM.

 Examples 12 to 14 (for comparison). The conditions of the hydrotreating process according to examples 12 to 13 are similar to example 1, and example 14 to example 11, except that at the first and second stages of hydrotreating, the same temperatures are set. The results obtained on the hydrotreatment process and the catalytic reforming of gasoline fractions are presented in table 2.

 Thus, the advantage of the proposed method is to increase the degree of hydrodesulfurization and hydrogenation of unsaturated compounds at significantly lower process temperatures, which allows the processing of secondary distillates in a mixture with straight-run diesel fuel in a higher ratio of up to 50 wt.% Without a significant exothermic effect of hydrogenation and hydrodesulfurization reactions , which in turn leads to a prolongation of the inter-regeneration cycle of the catalysts and, ultimately, the total service life pussies. In addition, providing coarse hydrogenation and hydrodesulfurization of the gasoline fraction allows its further refinement by catalytic reforming without poisoning the reforming catalyst, while ensuring a significant increase in the octane number of gasoline, that is, the most qualified use of low-quality gasoline fractions of thermal processes. The advantages of the proposed method also lie in the fact that it allows simultaneously with straight-run diesel fuel to refine light gas oils of thermal processes with their high content in hydrotreating raw materials (up to 50 wt.%) To obtain high-quality environmentally friendly commercial diesel fuel with sulfur content up to 500 ppm This solves the issue of the qualified use of unstable gas oils of secondary origin and an increase in the production of commercial diesel fuel with an unchanged assortment of oils processed at oil refineries.

Claims (3)

1. A method of processing distillates of secondary origin in a mixture with a straight-run fraction, by hydrotreating at elevated temperature and pressure in the presence of hydrogen, followed by separation of the fraction and its catalytic reforming, characterized in that they process distillates of secondary origin boiling in the temperature range 21-205 ^o С and / or 140-360 ^o C, and the fraction with a boiling end 185 ^o C its catalytic reforming, a hydrotreating process is carried out in two steps with intermediate mixture heated at gazosyrevoy kata izatorah hydrotreating catalysts at a weight ratio of the first and second steps of 1: 2-6. 2. The method according to claim 1, characterized in that the hydrotreating is carried out at a temperature in the first stage of 200-320 ^{o C.} and in the second stage 280-380 ^o C. 3. The method according to p. 1, characterized in that the hydrotreatment is subjected to either a separate fraction of the secondary distillates (21-205 ^o C or 140-360 ^o C) in a mixture with straight-run fraction, or a mixture of secondary distillates (21-205 ^o C and 140 -360 ^o C) with straight run fraction in the ratio of secondary: straight run 5-50: 95-50%.

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