RU2711756C1 - Method for catalytic cracking of vacuum gas oil - Google Patents

Abstract

FIELD: oil and gas industry.SUBSTANCE: invention relates to oil refining industry, namely to catalytic cracking of vacuum gas oil. Method for catalytic cracking of vacuum gas oil is characterized by that it includes preliminary heating of material to temperature at which vacuum gas oil passes into liquid state, then adding a mixture containing hydrogen peroxide with concentration of 20–37 wt% and a catalyst, having the following composition (wt%): concentrated formic acid 80±5, water 13±5, compound containing molybdenum 4±1, surfactant, soluble and stable in catalyst 2±0.5, interphase carrier 1±0.1, obtained reaction mixture is stirred at temperature, at which vacuum gas oil passes into liquid state for 1–2 hours, then at temperature of 60±10 °C for another 1–2 hours and further 4 hours ± 10 min at temperature 80±5 °C, upon completion of reaction, the mixture is heated to 100±5 °C and adding an extractant for extraction of oxidation products, is mixed for 5–10 minutes at this temperature and the extractant is separated to obtain purified vacuum gas oil, then the obtained desulphurised vacuum gas oil is subjected to catalytic cracking using a zeolite-containing catalyst at temperature of 480–540 °C, pressure of 0.1–0.3 MPa and mass feed rate of 12.2–20 hto obtain a wide fraction of catalytic cracking with high content of gasoline fraction.EFFECT: reduction of amount of sulfur in liquid products of catalytic cracking, increased output of gasoline fraction and low output of coke during cracking when using pre-oxidized vacuum gasoil as raw material.7 cl, 2 tbl

Description

Technical field

The group of inventions relates to the field relates to the refining industry, and in particular to the field of catalytic cracking of vacuum gas oil. The proposed method for reducing sulfur and a catalytic composition can be used in the oil refining industry to obtain catalytic cracking products with a lower sulfur and coke content.

State of the art

High sulfur content in motor fuels leads to corrosion of equipment. And fuel combustion products (sulfur oxides) are harmful to the environment, in particular, they cause acid rain. In this regard, it is necessary to look for ways to reduce the sulfur content in motor fuels, which are obtained by mixing gasoline fractions from a number of processing processes, including the catalytic cracking process. It is economically advantageous that, as a result of applying the new method for producing cracking products, in addition to reducing the sulfur content, the yield of the target product, the gasoline fraction, will increase. Also, reducing the coke yield increases the conversion of the process and allows to increase the life of the catalyst.

Traditionally, in industry, methods related to the use of hydrogen are used to reduce sulfur in vacuum gas oil: hydrotreating and hydrocracking. In connection with the extensive experience in using these methods, the conditions and parameters of further processing are widely studied. The use of an anhydrous method of processing petroleum feedstock - oxidative desulfurization will reduce the amount of sulfur without the use of hydrogen, which can reduce capital costs and positively affect the quality of vacuum gas oil.

The prior art methods for the preliminary purification of raw materials for catalytic cracking based on the extraction of polycyclic aromatic hydrocarbons and heteroatomic compounds, including organosulfur (RU 2203306, published 04/27/2003, CL C10G 21/00). However, this method is aimed only at polycyclic aromatic compounds, which significantly reduces its effectiveness for achieving high degrees of desulfurization of petroleum products.

A number of catalysts are known containing molybdenum and cobalt for use in hydrotreating (RU 2626400, published 07/27/2017, CL C10G 45/08, B01J 31/22, B01J 23/882, RU 2626398, published 07/27/2017, CL B01J 21 / 02). However, as mentioned above, methods for the desulphurization of gas oil using hydrogen require high capital costs. The use of hydrogen leads to a decrease in the octane number due to the hydrogenation of unsaturated compounds.

The technical problem to be solved by the claimed group of inventions is the development of a method for producing vacuum gas oil cracking products with sulfur and coke contents lower than when obtaining cracked products from hydrotreated vacuum gas oil and a catalytic composition for this.

Disclosure of invention

The technical result of this group of inventions is the development of a method that allows to obtain liquid cracking products with a lower sulfur content and reduced coke formation on a cracking catalyst in comparison with the same indicators for vacuum gas oil cracking products that have previously been hydrotreated. When using this method, in which at the first stage non-purified vacuum gas oil is subjected to oxidative desulfurization with a catalytic composition, the yield of the gasoline fraction increases by 3-8%, the yield of coke decreases by 2-3%, and the sulfur content decreases by 2-6% by weight compared to cracking of hydrotreated vacuum gas oil.

The technical result is achieved due to the fact that the method of oxidative desulfurization of vacuum gas oil includes the following main steps:

1) preliminary heating of vacuum gas oil to a liquid state;

2) oxidation of the mixture with hydrogen peroxide in the presence of a catalyst;

3) removal of oxidation products by extraction at elevated temperature using N-methylpyrrolidone or N-ethylpyrrolidone or pyrrolidone;

4) catalytic cracking of desulfurized vacuum gas oil.

At the first stage, the vacuum gas oil is preheated to the temperature necessary for the transition of the vacuum gas oil to a liquid state, followed by stepwise heating of the feed to 80 ° C ± 5 ° C, oxidation of the resulting mixture with hydrogen peroxide with a concentration of 20-37 mass. % in the presence of a catalyst, which includes:

- concentrated formic acid,

- a compound containing molybdenum

- phase transition catalyst (interphase carrier)

- substances to improve the emulsion properties of the catalyst.

To carry out the oxidation reaction, components are taken in the following weight ratios:

catalyst: sulfur in vacuum gas oil = 1: 6 to 1:20

hydrogen peroxide: sulfur in vacuum gas oil = 6: 1 to 20: 1

in this case, a catalyst is added to the hydrogen peroxide solution first, the mixture is stirred at a speed of at least 600 rpm until a homogeneous mixture is formed, and then the resulting mixture is added to a vacuum gas oil preheated to a liquid state. The resulting mixture is stirred at a given temperature (the minimum temperature at which vacuum gas oil turns into a liquid state) for 1 hour ± 10 min, then at a temperature of 60 ° C ± 10 ° C for another 1 hour ± 10 min and then 4 hours ± 10 min at a temperature of 80 ° C ± 5 ° C. At the end of the reaction, the mixture is heated to 100 ° C ± 5 ° C and the extractant N-methylpyrrolidone or N-ethylpyrrolidone or pyrrolidone (in the volume ratio of raw materials: extractant 1: 1 ± 10% vol.) Is added, stirred for 5-10 min at a temperature of 100 ° C ± 5 ° C and the extractant is separated to obtain purified vacuum gas oil (the extractant is selected so that it does not mix with vacuum gas oil, so after mixing is turned off, a two-phase extractant system is formed: vacuum gas oil with a clear interface, the extractant is removed by any available from special, in particular by decantation etc.).

The speed of stepwise heating is set to not more than 10 ° C per minute.

The technical result is also achieved by the composition of the catalytic composition for the oxidative desulfurization of vacuum gas oil. The catalytic composition for the oxidative desulfurization of vacuum gas oil includes the following components (wt.%):

Concentrated Formic Acid 80 ± 5

Water 13 ± 5

Compound containing molybdenum 4 ± 1

Soluble and stable surfactant in the catalyst 2 ± 0.5

Phase transition catalyst (phase transfer carrier) 1 ± 0.1

In this case, the compound containing molybdenum can be ammonium molybdate, sodium molybdate, ammonium paramolybdate, sodium paramolybdate, as a surfactant, soluble and stable in the catalyst — Neonol AF 9-6 or amine N-oxide, and use as an interphase carrier tetrabutylammonium bromide or tetraoctylammonium bromide.

The implementation of the invention

The inventive catalyst composition for the oxidative desulfurization of vacuum gas oil includes the following components (wt.%): Concentrated formic acid 80 ± 5; water 13 ± 5; a compound containing 4 ± 1 molybdenum selected from the group consisting of ammonium molybdate, sodium molybdate, ammonium paramolybdate, sodium paramolybdate; neonol AF 9-6 or N-amine oxide 2 ± 0.5; tetrabutylammonium bromide or tetraoctylammonium bromide 1 ± 0.1.

The catalyst is prepared by sequentially dissolving the components in a mixture of formic acid and water. Pre-mix water and concentrated formic acid, then add the remaining components, while the order of addition of the components can be arbitrary. After adding each component, the mixture is mixed by any available method, ensuring a homogeneous solution. Each subsequent component is added after complete dissolution of the previous component.

This catalyst composition allows the preparation of active peroxocomplexes in the presence of hydrogen peroxide, as well as peroxyacids in the form of formic acid. The addition of Neonol AF 9-6 or amine N-oxide to the system improves emulsification of the mixture of catalyst and hydrogen peroxide in a vacuum gas oil environment, and the addition of tetrabutylammonium bromide or tetraoxylammonium bromide can reduce interfacial limitations and increase the reaction rate. The specified catalyst is obtained by sequentially adding the indicated components to water with constant stirring and until each component is completely dissolved, while the order of adding the components is not regulated and does not affect the composition and properties of the resulting catalyst.

It is possible to carry out catalytic cracking at plants with different hardware solutions: a stationary and moving catalyst bed, a fluidized catalyst bed and an elevator reactor. In this case, it is possible to use the standard method of separation of products. Cracking is carried out at a temperature of 480-540 ° C and a pressure of 0.1-0.3 MPa, passing 1.33 ± 0.03 g of raw material for 75 ± 1 seconds through a stationary catalyst bed weighing 3.2-5.2 g, which corresponds to a mass feed rate of 12.2-20 h ^-1 . The catalyst used is an industrial equilibrium zeolite-containing cracking catalyst, the properties of which are presented below.

The catalytic cracking of vacuum gas oil is carried out according to the following points:

1. Loading the catalyst into the reactor, heating the vacuum gas oil to 50 ± 5 ° C for its melting and easier feeding into the reactor

2. Heating the reactor to a predetermined temperature (480-540 ° C) in an argon flow

3. Purge the reactor, heated to a predetermined temperature, with an argon flow for 15 minutes at a speed of 30 cm ³ / min

4. Feeding 1.33 ± 0.03 g of raw material in 75 seconds

5. Purge the reactor in a stream of argon for 10 minutes at a speed of 30 cm ³ / min

6. Collecting liquid products in a receiver flask placed in an ice bath

7. The resulting liquid products are weighed, analyze the fractional composition and sulfur content

8. The rector is cooled to room temperature, the amount of coke is determined gravimetrically

Thus, the use of this sequence of processing processes allows to obtain liquid cracking products with less sulfur and coke yield.

Below is a more detailed description of the claimed invention. The present invention may be subjected to various changes and modifications understood by one skilled in the art upon reading this description. Such changes do not limit the scope of claims.

At the first stage, vacuum gas oil is preheated to the temperature necessary for the transition of vacuum gas oil to a liquid state, namely, the raw material is heated to a temperature of 40 ° C ± 5 ° C, followed by stepwise heating of the raw material to 80 ° C ± 5 ° C. Wherein. Heated by a method that provides uniform heating at a speed of not more than 10 ° C per minute of the entire reaction mass.

Heating can be carried out in a water bath or in a reactor with a thermostatically controlled jacket.

At the second stage, the sulfur-containing components of the vacuum gas oil are oxidized with hydrogen peroxide in the presence of a catalyst. Use hydrogen peroxide in a concentration of 20-37 mass. % The catalyst is preliminarily added to a weighed portion of hydrogen peroxide and the mixture is stirred until a homogeneous mixture is formed. The resulting mixture was added to the feedstock. The components for the oxidation reaction are taken in the following weight ratios.

catalyst: sulfur in vacuum gas oil = 1: 6 to 1:20

hydrogen peroxide: sulfur in vacuum gas oil = 6: 1 to 20: 1

Moreover, the oxidation reaction is carried out with constant stirring of the mixture at a speed of at least 600 rpm for a mixture of 6 ± 1 h, and the temperature of the mixture is raised stepwise to 80 ° C ± 5 ° C to minimize decomposition of hydrogen peroxide.

In the third stage, the mixture was heated to 100 ° C ± 5 ° C and N-methylpyrrolidone or N-ethylpyrrolidone or pyrrolidone (in a volume ratio of raw materials: extractant 1: 1 ± 10% by volume) was added to extract oxidation products, stirred for 5-10 min at temperature 100 ° C ± 5 ° C and the extractant was separated to obtain purified vacuum gas oil.

The sulfur content in the initial vacuum gas oil in mass fractions is predetermined by any method known from the prior art (a method based on the oxidation of sulfur and analysis of the obtained oxides; a method based on the recovery of sulfur to hydrogen sulfide; spectral method, etc.).

At the third stage, the obtained products of the oxidation of organosulfur compounds are extracted with N-methylpyrrolidone or N-ethylpyrrolidone or pyrrolidone. The extraction is carried out at a temperature of 100 ° C ± 5 ° C.

The fourth stage involves the catalytic cracking of sulfur-free vacuum gas oil.

Catalytic cracking is carried out in an installation that complies with ASTM d 3907-13. The experiment is carried out with a stationary catalyst bed at a temperature of 480-540 ° C, with a mass feed rate of 14.5-20.0 h ^-1 (supply of 1.33 g of feedstock for 75 ± 1 seconds through a catalyst bed of 3.2- 5.2 g). The catalyst used is an industrial equilibrium zeolite-containing cracking catalyst. Non-hydrotreated vacuum gas oil, non-hydrotreated vacuum gas oil subjected to oxidative desulfurization and hydrotreated vacuum gas oil are used as raw materials.

The fractional composition of liquid cracking products was determined by simulated distillation on a Lame GC-1000 chromatograph. The sulfur concentration in the liquid cracking products was determined using an ASE-2 energy dispersive X-ray fluorescence analyzer. The coke content on the catalyst was determined by the gravimetric method.

Catalytic cracking was carried out on a sample of desulfurized vacuum gas oil with the lowest sulfur content.

The following are examples of specific embodiments of oxidative desulfurization of non-hydrotreated vacuum gas oil (NGVG).

The total sulfur content in the initial vacuum gas oil was preliminarily analyzed by the X-ray fluorescence method on an ASE-2 instrument. Oxidative desulphurization of a vacuum gas oil sample with a total sulfur content of 14,400 ppm was carried out using an aqueous solution of hydrogen peroxide (concentration of 20-37 wt.%) In the presence of a catalyst (the composition of the catalyst in each example, the amount of catalyst and hydrogen peroxide taken, oxidation and extraction conditions are given in table 1).

The oxidation was carried out with constant stirring of the mixture at a speed of at least 600 rpm for a mixture of 6 ± 1 h, and the temperature of the mixture was raised stepwise to 80 ° C ± 5 ° C to minimize decomposition of hydrogen peroxide.

At the end of the reaction, the mixture was heated to 100 ° C ± 5 ° C and N-methylpyrrolidone or N-ethylpyrrolidone or pyrrolidone (in a volume ratio of feed: extractant 1: 1 ± 10% vol.) Was added to extract oxidation products, stirred for 5-10 min at a temperature of 100 ° C ± 5 ° C and the extractant was separated to obtain purified vacuum gas oil. The results are shown in table 1.

General methodology for the catalytic cracking of vacuum gas oil.

Non-hydrotreated vacuum gas oil (NG VG) with a sulfur content of 14,400 ppm, non-hydrotreated vacuum gas oil (NG OVG) preliminarily subjected to oxidative desulfurization and hydrotreated vacuum gas oil (GO VG) with a sulfur content of 3600 ppm were used as raw materials. Catalytic cracking was carried out with a mass feed rate of 12.2-20 h ^-1 at 480-540 ° C. Liquid products were separated and the fractional composition and sulfur content were determined (Table 2).

Claims (9)

1. The method of catalytic cracking of vacuum gas oil, characterized in that it involves preheating the feed to a temperature at which the vacuum gas oil goes into a liquid state, then add a mixture comprising hydrogen peroxide with a concentration of 20-37 wt.% And a catalyst of the following composition (wt. .%): concentrated formic acid 80 ± 5 water 13 ± 5 molybdenum compound 4 ± 1 surface-active substance, soluble and stable in the catalyst 2 ± 0.5 interphase carrier 1 ± 0.1, the resulting reaction mixture is stirred at a temperature at which the vacuum gas oil turns into a liquid state for 1-2 hours, then at a temperature of 60 ° C ± 10 ° C for another 1-2 hours and then 4 hours ± 10 min at a temperature of 80 ° C ± 5 ° C, at the end of the reaction, the mixture is heated to 100 ° C ± 5 ° C and the extractant is added to extract the products of oxidation, stirred for 5-10 minutes at this temperature and the extractant is separated to obtain purified vacuum gas oil, then the resulting desulfurized vacuum gas oil subjected to catalytic cracking using the use of a zeolite-containing catalyst at a temperature of 480-540 ° C, a pressure of 0.1-0.3 MPa and a mass feed rate of 12.2-20 h ^-1 to obtain a wide catalytic cracking fraction with a high content of gasoline fraction. 2. The method according to p. 1, characterized in that the extractant is taken in a volume ratio of raw materials: extractant 1: 1 ± 10% vol. 3. The method according to p. 1, characterized in that as extractants for the separation of oxidation products using N-methylpyrrolidone, N-ethylpyrrolidone, pyrrolidone. 4. The method according to p. 1, characterized in that the speed of stepwise heating is not more than 10 ° C per minute. 5. The method according to p. 1, characterized in that the compound containing molybdenum is selected from the group comprising ammonium molybdate, sodium molybdate, ammonium paramolybdate, sodium paramolybdate. 6. The method according to p. 1, characterized in that as a surfactant use Neonol AF 9-6 or N-amine oxide. 7. The method according to claim 1, characterized in that tetrabutylammonium bromide or tetraoctylammonium bromide is used as an interphase carrier.