CN112410066B

CN112410066B - Process for reducing sulfur content of vacuum residuum

Info

Publication number: CN112410066B
Application number: CN201910781709.2A
Authority: CN
Inventors: 许金山; 陈辉; 曹发海; 许晓斌; 许军
Original assignee: China Petroleum and Chemical Corp; Qilu Petrochemical Co of Sinopec
Current assignee: China Petroleum and Chemical Corp; Qilu Petrochemical Co of Sinopec
Priority date: 2019-08-23
Filing date: 2019-08-23
Publication date: 2022-08-16
Anticipated expiration: 2039-08-23
Also published as: CN112410066A

Abstract

The invention belongs to the technical field of petrochemical industry, and particularly relates to a method for reducing sulfur content of vacuum residue. Mixing the vacuum residue, an oxidant, a catalyst and an extractant, heating and pressurizing in a nitrogen atmosphere to enable the extractant to enter a supercritical state, carrying out catalytic oxidation reaction on the vacuum residue in the supercritical state, standing and layering after the reaction is finished, and separating the extractant to obtain the vacuum residue with the sulfur content reduced to below 2.0%. The method for reducing the sulfur content of the vacuum residue, disclosed by the invention, has the advantages that the whole operation process is carried out under the non-hydrogenation condition, so that the requirements on devices and raw materials are reduced; the sulfur content of the obtained vacuum residue is reduced, and the obtained vacuum residue can be used as a raw material to produce products such as low-sulfur petroleum coke and the like which meet the requirements; by improving the product quality of the vacuum residue oil which is poor raw oil, the processing amount, the operating rate and the economic benefit of the delayed coking device can be improved.

Description

Process for reducing sulfur content of vacuum residuum

Technical Field

The invention belongs to the technical field of petrochemical industry, and particularly relates to a method for reducing sulfur content of vacuum residue.

Background

With the decreasing of conventional petroleum resources, the deterioration and heaviness of crude oil become global trend, the production proportion of crude oil with high sulfur content, high density and high metal content becomes higher and higher, and the deep processing of heavy oil becomes a common problem facing the world oil refining industry. The delayed coking process as one important residual oil decarbonizing process is to heat heavy oil, such as vacuum slag oil, fast to 500 deg.c inside a heating furnace to delay the heating to cracking and condensation in a coke tower to produce oil, gas, coke and other products, and has the advantages of low cost, high conversion rate (70-75%), high return on investment, etc. and is especially suitable for treating heavy oil and extra heavy oil with high sulfur content, high metal content, high specific weight and high processing capacity. Petroleum coke is a main byproduct generated in a residual oil delayed coking process, has high carbon content, high heat value and low volatile and ash content, and can be used as a power plant fuel and a graphite electrode in smelting industry. Along with the annual increase of the import quantity of crude oil in domestic petrochemical enterprises, the sulfur content of petroleum coke produced by each refining enterprise is high; in recent years, environmental laws and regulations are increasingly strict, and the standard of sulfur content of a factory-delivered oil product is improved, so that products such as high-sulfur petroleum coke and heavy fuel oil cannot be delivered from a factory, and flow selection and device setting of a refinery are greatly influenced. Therefore, whether an effective process for reducing the sulfur content of the vacuum residue can be developed becomes a key factor for restricting the production of high-quality petroleum coke and even influencing the operation rate of a delayed coking device.

The traditional sulfur content reduction process in the refining enterprise mainly comprises the following steps: firstly, hydrodesulfurization is carried out, and sulfur element in residual oil is separated from a system in a hydrogen sulfide form by carrying out catalytic hydrogenation at certain pressure and temperature, but due to steric hindrance effect, the thiophene sulfur with high stability has low activation degree when interacting with a catalyst, and is difficult to be directly removed by hydrogenolysis, especially dibenzothiophene sulfides; thiophenic sulfur is the major sulfur-containing compound in the residue, and therefore, the hydrodesulfurization process is not suitable for treating vacuum residue. The oxidation desulfurization technology is to selectively oxidize the thiophene sulfur into sulfoxide or sulfone compounds with stronger polarity under the action of an oxidant, so that the sulfide is extracted to a polar phase to realize the separation from an oil product; compared with hydrodesulfurization, the oxidative desulfurization technology is easier to remove thiophenic sulfur, and the oxidative desulfurization can realize the conversion removal of sulfide under the conditions of relatively low temperature and low pressure. However, the prior oxidative desulfurization process is mainly applied to the desulfurization of light oil products, while for heavy oil such as vacuum residue oil, the reaction efficiency is reduced due to the resistance effect caused by high viscosity and low fluidity, and there is a fresh literature relating to the oxidative desulfurization of residue oil. Aiming at the problems of poor flowability and low reaction activity of heavy raw oil, the supercritical technology is more applied to the treatment of residual oil, and the residual oil and the solvent in a supercritical state are fused in a uniform state, so that the problem of insufficient contact between a water-soluble oxidant and the residual oil is solved, and the oxidation and extraction processes are fully carried out.

In the prior art related to oil product desulfurization, patent CN108993526A discloses a gasoline desulfurization treatment method, wherein a fixed bed reactor is adopted to perform catalytic treatment on gasoline, so that clean gasoline with ultra-low sulfur, low olefin and high octane number can be produced, but the whole process needs to be carried out in a hydrogen environment, the volume ratio of hydrogen to oil is 160-460: 1, the hydrogen consumption is high, and the equipment requirement is high; patent CN108219835A proposes a naphtha desulfurization method, which comprises synthesizing a solid particle type desulfurization adsorbent, and statically putting the adsorbent into naphtha to realize oil product desulfurization, but the adsorbent itself has poor stability, the whole process needs to strictly control water content, and the oil product desulfurization effect is not clear; patent CN108795484A adopts heteropoly acid quaternary ammonium salt-formic acid as a catalyst, uses oxygen to perform catalytic oxidation on diesel oil in a reaction kettle, adds a certain amount of N-methyl pyrrolidone into the reaction product diesel oil to perform ultrasonic oscillation extraction, stands for 15-30 min, collects a diesel oil layer to obtain a finished product low-sulfur diesel oil, the whole process can effectively remove benzothiophene, dibenzothiophene and derivatives thereof in the diesel oil, the cost can be effectively reduced by using environment-friendly oxygen as an oxidant, but the treated object is still light oil such as diesel oil and the like, and the reduction of the sulfur content of heavy oil cannot be realized; in patent CN101612595, by utilizing subcritical and supercritical hydrothermal synthesis reaction and strong permeation of subcritical and supercritical water, a medium-temperature desulfurizer which has the characteristics of high desulfurization precision, good cycle stability, high mechanical strength and the like within the range of 250-450 ℃ is prepared, can be applied to removal of hydrogen sulfide in medium-temperature coal gas or natural gas, but is not involved in removal of sulfur-containing compounds of heavy oil products; CN101077980A discloses a method for preparing light oil by supercritical water modified vacuum residue, vacuum residue and water are added into an autoclave, the autoclave is cooled after being stabilized for 18-60 min under the conditions of pressure of 20-35 MPa and temperature of 380-460 ℃, 60-87% light oil is obtained, and attachments in the autoclave can be washed and recovered by using n-heptane, n-hexane, toluene or tetrahydrofuran as solvents.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: overcomes the defects of the prior art and provides a method for reducing the sulfur content of vacuum residue. The reaction product is automatically separated at normal temperature, the whole process is simple, the whole operation is carried out under the non-hydrogenation condition, and the requirements on devices and raw materials are reduced; the sulfur content of the obtained vacuum residue is reduced, and products such as low-sulfur petroleum coke and the like which meet the requirements can be produced by using the vacuum residue as a raw material; by improving the product quality of the vacuum residue oil which is poor raw oil, the processing amount, the operating rate and the economic benefit of the delayed coking device can be improved.

The method for reducing the sulfur content of the vacuum residue comprises the steps of mixing the vacuum residue, an oxidant, a catalyst and an extracting agent, heating and pressurizing under the nitrogen atmosphere to enable the extracting agent to enter a supercritical state, carrying out catalytic oxidation reaction on the vacuum residue under the supercritical state, standing and layering after the reaction is finished, and separating the extracting agent to obtain the vacuum residue with the sulfur content reduced to below 2.0%.

Wherein:

the supercritical catalytic oxidation reaction temperature is 260 ℃ to 290 ℃, the reaction pressure is 5.5 to 8.5MPa, and the reaction time is 3 to 6 hours; wherein the reaction temperature and pressure are in excess of the critical temperature and pressure of the extractant used.

The oxidant is one of aromatic aldehyde or peroxide.

Preferably, the oxidizing agent is one of benzaldehyde, terephthalaldehyde, cumyl hydroperoxide or di-tert-butyl peroxide.

The mass ratio of the oxygen content in the oxidant to the sulfur content in the vacuum residue is 2:1-5: 1.

The catalyst is one of cobalt oxide, manganese oxide, sodium tungstate or cobalt chloride, and the mass of the added catalyst is 2-10% based on the mass of sulfur element in the vacuum residue.

The extractant is one of methanol or acetonitrile, and the mass ratio of the added extractant to the vacuum residue is 1:1-3: 1. The vacuum residue is obtained by an atmospheric and vacuum distillation process; the sulfur content of the vacuum residue is 2.5-3.5%, and the density is 1010- ^-3 。

The invention mixes the vacuum residue produced by the atmospheric and vacuum distillation process with oxidant, catalyst and extractant in proportion, and the catalytic oxidation reaction is carried out in a reactor under certain process conditions, so that the polarity of the sulfur-containing compound in the vacuum residue is enhanced, and the sulfur-containing compound is enriched from the residue to the extractant through the extraction; the mixture after the reaction is cooled to realize layering, and the vacuum residue with reduced sulfur content is obtained after the extractant is separated out, and can be used as a delayed coking raw material to produce products such as petroleum coke with low sulfur content.

Compared with the prior art, the invention has the following beneficial effects:

(1) according to the method for reducing the sulfur content of the vacuum residue, the oxidation desulfurization technology and the supercritical desulfurization technology are combined, the oxidation and extraction processes of the oxidation desulfurization process are combined with the supercritical state in a non-hydrogen state, so that the oxidation and the extraction are carried out in the same unit, the interphase mass transfer resistance is eliminated by utilizing the supercritical state, and the transfer efficiency is increased; after the reaction is finished, the two liquid phases can be automatically separated, and the sulfide is extracted to the polar phase, so that the deep desulfurization of the residual oil is realized. Compared with the traditional hydrogenation process, the method reduces the requirements on devices and raw materials, and has important significance for improving and perfecting heavy oil processing means and improving enterprise economic benefits.

(2) According to the method for reducing the sulfur content of the vacuum residue, oxidation and extraction are carried out in the same unit, so that the intercalary mass transfer resistance is effectively eliminated by utilizing a supercritical state, and the transfer efficiency is increased; meanwhile, the reaction product can be automatically separated at normal temperature, the whole process is simple, and the benzothiophene sulfur-containing compounds in the residual oil are removed.

(3) The method for reducing the sulfur content of the vacuum residue, disclosed by the invention, has the advantages that the whole operation process is carried out under the non-hydrogen (no hydrogen participation) condition, so that the requirements on devices and raw materials are reduced; the sulfur content of the obtained vacuum residue is reduced, and the obtained vacuum residue can be used as a raw material to produce products such as low-sulfur petroleum coke and the like which meet the requirements; by improving the product quality of the vacuum residue oil which is poor raw oil, the processing amount, the operating rate and the economic benefit of the delayed coking device can be improved.

Detailed Description

The present invention is further described below with reference to examples.

The vacuum residues used in the examples were obtained from the Qilu division, a company, petrochemical Co., Ltd., China, and the basic properties thereof are shown in Table 1. The used oxidants benzaldehyde, terephthalaldehyde, cumyl hydroperoxide and di-tert-butyl peroxide are all sold in the market; the catalysts cobalt oxide, manganese oxide, sodium tungstate and cobalt chloride are all sold in the market; the extractants methanol and acetonitrile are commercially available.

Example 1

Weighing 50g of vacuum residue and 50g of methanol, weighing an oxidant benzaldehyde with the oxygen element content of 200% and a catalyst cobalt oxide with the oxygen element content of 5% based on the mass of sulfur elements in the vacuum residue, adding the oxidant benzaldehyde and the catalyst cobalt oxide into the methanol to serve as extraction liquid, respectively adding the vacuum residue and the extraction liquid into a reaction kettle, heating and pressurizing to 260 ℃ and 8.5MPa in the nitrogen atmosphere, and fully stirring for carrying out catalytic oxidation reaction for 3 hours. After the reaction is finished, standing the reaction kettle at room temperature for 1h, and separating an upper-layer extracting agent to obtain the vacuum residue with low sulfur content; the sulfur content of the residual oil product is measured by a microcomputer coulomb sulfur detector, and the sulfur content of the product and the reaction desulfurization rate are shown in a table 3.

Example 2

Weighing 50g of vacuum residue and 50g of methanol, weighing an oxidant terephthalaldehyde with the oxygen element content of 300% and a catalyst manganese oxide with the oxygen element content of 5% based on the mass of sulfur elements in the vacuum residue, adding the oxidant terephthalaldehyde and the catalyst manganese oxide into the methanol to serve as extraction liquid, respectively adding the vacuum residue and the extraction liquid into a reaction kettle, heating and pressurizing to 270 ℃ and 8.5MPa in the nitrogen atmosphere, and fully stirring for catalytic oxidation reaction for 4 hours. After the reaction is finished, standing the reaction kettle at room temperature for 1h, and separating an upper-layer extracting agent to obtain the vacuum residue with low sulfur content; the sulfur content of the residual oil product is measured by a microcomputer coulomb sulfur detector, and the sulfur content of the product and the reaction desulfurization rate are shown in a table 3.

Example 3

Weighing 50g of vacuum residue and 50g of acetonitrile, weighing an oxidant namely cumyl hydroperoxide with the oxygen content of 400 percent and a catalyst sodium tungstate with the oxygen content of 5 percent into the acetonitrile by taking the mass of sulfur elements in the vacuum residue as a reference, adding the vacuum residue and the extract into a reaction kettle respectively, heating and pressurizing to 280 ℃ and 5.5MPa in the nitrogen atmosphere, and fully stirring for carrying out catalytic oxidation reaction for 5 hours. After the reaction is finished, standing the reaction kettle at room temperature for 1h, and separating an upper-layer extracting agent to obtain the vacuum residue with low sulfur content; the sulfur content of the residual oil product is measured by a microcomputer coulomb sulfur detector, and the sulfur content of the product and the reaction desulfurization rate are shown in a table 3.

Example 4

Weighing 50g of vacuum residue and 50g of acetonitrile, weighing an oxidant of di-tert-butyl peroxide with the oxygen element content of 500% and a catalyst of cobalt chloride with the oxygen element content of 5% based on the mass of sulfur elements in the vacuum residue, adding the oxidant of di-tert-butyl peroxide with the oxygen element content of 5% and the catalyst of cobalt chloride into the acetonitrile to serve as extraction liquid, respectively adding the vacuum residue and the extraction liquid into a reaction kettle, raising the temperature and pressurizing to 290 ℃ and 5.5MPa in the nitrogen atmosphere, and fully stirring for carrying out catalytic oxidation reaction for 6 hours. After the reaction is finished, standing the reaction kettle at room temperature for 1h, and separating an upper-layer extracting agent to obtain the vacuum residue with low sulfur content; the sulfur content of the residual oil product is measured by a microcomputer coulomb sulfur detector, and the sulfur content of the product and the reaction desulfurization rate are shown in a table 3.

Table 1 examples 1-4 vacuum resid base properties

TABLE 2 TABLE of relationship between reaction conditions and raw material amounts in examples 1 to 4

TABLE 3 Sulfur content of product and reaction desulfurization rates of examples 1-4

Item	Example 1	Example 2	Example 3	Example 4
					The sulfur content of the raw material%	2.83	2.96	2.78	3.05
After treatment, the sulfur content%	1.92	1.89	1.74	1.86
					Desulfurization rate/%)	32.2	36.1	37.4	39.1

Claims

1. A method for reducing the sulfur content of vacuum residue is characterized in that: mixing the vacuum residue, an oxidant, a catalyst and an extractant, heating and pressurizing in a nitrogen atmosphere to enable the extractant to enter a supercritical state, carrying out catalytic oxidation reaction on the vacuum residue in the supercritical state, standing and layering after the reaction is finished, and separating the extractant to obtain the vacuum residue with the sulfur content reduced to below 2.0%;

the supercritical catalytic oxidation reaction temperature is 260 ℃ to 290 ℃, the reaction pressure is 5.5 to 8.5MPa, and the reaction time is 3 to 6 hours;

the oxidant is one of aromatic aldehyde or peroxide.

2. The process for reducing the sulfur content of vacuum residuum of claim 1 characterized by: the oxidant is one of benzaldehyde, terephthalaldehyde, cumyl hydroperoxide or di-tert-butyl peroxide.

3. The process for reducing the sulfur content of vacuum residuum of claim 1 characterized by: the mass ratio of the oxygen content in the oxidant to the sulfur content in the vacuum residue is 2:1-5: 1.

4. The process for reducing the sulfur content of vacuum residuum of claim 1 characterized by: the catalyst is one of cobalt oxide, manganese oxide, sodium tungstate or cobalt chloride, and the mass of the added catalyst is 2-10% based on the mass of sulfur element in the vacuum residue.

5. The process for reducing the sulfur content of vacuum residuum of claim 1 characterized by: the extractant is one of methanol or acetonitrile, and the mass ratio of the added extractant to the vacuum residue is 1:1-3: 1.