CN111718748A - Method for removing oxygen-containing compounds from Fischer-Tropsch synthetic oil - Google Patents

Method for removing oxygen-containing compounds from Fischer-Tropsch synthetic oil Download PDF

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CN111718748A
CN111718748A CN201910214185.9A CN201910214185A CN111718748A CN 111718748 A CN111718748 A CN 111718748A CN 201910214185 A CN201910214185 A CN 201910214185A CN 111718748 A CN111718748 A CN 111718748A
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extraction
content
stage
phase
fraction
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李丽
朱豫飞
缪平
孙琦
盖青青
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China Energy Investment Corp Ltd
National Institute of Clean and Low Carbon Energy
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China Energy Investment Corp Ltd
National Institute of Clean and Low Carbon Energy
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    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G53/00—Treatment of hydrocarbon oils, in the absence of hydrogen, by two or more refining processes
    • C10G53/02—Treatment of hydrocarbon oils, in the absence of hydrogen, by two or more refining processes plural serial stages only
    • C10G53/04—Treatment of hydrocarbon oils, in the absence of hydrogen, by two or more refining processes plural serial stages only including at least one extraction step
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G2300/00—Aspects relating to hydrocarbon processing covered by groups C10G1/00 - C10G99/00
    • C10G2300/10—Feedstock materials
    • C10G2300/1022—Fischer-Tropsch products
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G2300/00—Aspects relating to hydrocarbon processing covered by groups C10G1/00 - C10G99/00
    • C10G2300/20—Characteristics of the feedstock or the products
    • C10G2300/201—Impurities
    • C10G2300/202—Heteroatoms content, i.e. S, N, O, P

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  • Oil, Petroleum & Natural Gas (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

The invention relates to the field of Fischer-Tropsch synthetic oil refining, and discloses a method for removing oxygen-containing compounds from Fischer-Tropsch synthetic oil, which comprises the steps of carrying out atmospheric and vacuum fractionation on the Fischer-Tropsch synthetic oil to obtain a first-stage fraction, a second-stage fraction and a third-stage fraction; (2) carrying out first extraction on the first-stage fraction by using a methanol aqueous solution to obtain an extract phase 1 and a raffinate phase 1; performing second extraction on the second-stage fraction by using a first ethanol aqueous solution to obtain an extract phase 2 and a raffinate phase 2; performing third extraction on the third-stage fraction by using a second ethanol aqueous solution to obtain an extract phase 3 and a raffinate phase 3; (3) and respectively washing the raffinate phase 1, the raffinate phase 2 and the raffinate phase 3 to obtain the deoxidized and refined Fischer-Tropsch synthetic oil. The method not only keeps the content of alpha-olefin in the process of removing the oxygen-containing compound, but also reduces the content of the oxygen-containing compound in the deoxidized and refined Fischer-Tropsch synthetic oil to be less than 100ppm, and has high oil recovery rate.

Description

Method for removing oxygen-containing compounds from Fischer-Tropsch synthetic oil
Technical Field
The invention relates to the field of Fischer-Tropsch synthetic oil refining, in particular to a method for removing oxygen-containing compounds from Fischer-Tropsch synthetic oil.
Background
α -olefin is an important organic feedstock and intermediate product with a wide range of applications.1-butene, 1-hexene and 1-octene used as comonomers in Polyethylene (PE) resins can improve PE performance.C6-C10The α -olefin used for producing plasticizer alcohol, PE products added with the plasticizer alcohol have better low-temperature flexibility, processability and outdoor weather resistance, and are particularly suitable for manufacturing cables, wires, automobile accessories or decorative parts8-C10The α -olefin can be used to synthesize poly- α olefin (PAO) lubricant, PAO is high-quality synthetic lubricant C11-C14By hydroxylation of α -alkenes to C12-C15α -olefin can also be used in the production of alkylbenzene or alkylphenol to prepare lubricating oil and additive.
The fischer-tropsch synthesis reaction is a reaction in which synthesis gas is formed into a series of compounds containing alkanes, alkenes and oxygen at a certain temperature and pressure and using an iron or cobalt catalyst. The carbon chain length of the product is from 1 to more than 100, the oxygen-containing compound is mainly fatty alcohol, and a small amount of acid, ester, ketone, aldehyde and the like are also contained, the olefin is mainly linear alpha-olefin, and the content of the alpha-olefin in the Fischer-Tropsch light oil can reach more than 50%.
The alpha-olefin in the Fischer-Tropsch synthesis product can be used for producing PAO (polycyclic aromatic hydrocarbons), alkyl benzene and the like. However, the oxygenates must first be removed because the oxygenates have a negative effect on both of these reactions. However, currently, the removal of oxygenates in industry mainly employs a method of hydrogenating compounds containing olefins, alkanes and oxygenates. Hydrogenation processes also accompany olefin hydrosaturation during the hydrogenation removal of oxygenates, which is not a desirable result.
Other methods for separating and extracting fatty alcohol and removing oxygen-containing compounds also comprise adsorption, extraction and the like.
US3485879 discloses a process for separating alcohols from olefins and alkanes by selective adsorption on alumina, but this process has a problem of difficult industrial scale-up.
US2746984 discloses the separation of aliphatic alcohols from alcohol-hydrocarbon mixtures by reacting boric acid with the alcohol in the alcohol-hydrocarbon mixture to form an ester, followed by extraction with solvents such as methanol, ethanol, water, etc., followed by hydrolysis of the borate ester to obtain the aliphatic alcohol. However, the method is complicated in operation because of two chemical reactions, namely esterification and hydrolysis, and the content of the oxygen-containing compounds in the separated hydrocarbon is not mentioned.
US2610977 discloses the separation of alcohols from hydrocarbons and in particular discloses a process for extraction with an aqueous solution of a lower alcohol, the lower alcohol being aqueous methanol, but using an extraction phase with an oil ratio of 8-9: 1, the dosage of the extractant is large, and the recovery solvent adopts a low-carbon hydrocarbon extraction mode.
GB716131 discloses extraction with aqueous solutions of lower alcohols, but because of the wide distillation range of the feed oil, the extraction of small molecular oxygen-containing compounds and large molecular oxygen-containing compounds with the same extractant results in high hydrocarbon content in the extract, and the azeotropic distillation method is used to remove residual hydrocarbons in the alcohol, but because of the large number of components of the system, there is often multi-azeotropic and the separation effect is not good.
CN101891589B discloses a method for extracting fatty alcohol, which comprises rectifying to divide fischer-tropsch product into four-stage fractions; and respectively extracting the four fractions by using water and ethanol aqueous solutions with different concentrations. In order to reduce the hydrocarbon content in the fatty alcohol, the method also comprises the step of back-extracting the alcohol phase obtained by the extraction by using alkanes with different carbon numbers respectively. However, the recovery rate of the aliphatic alcohol was only about 95%, and it was found that the amount of the oxygen-containing compound remaining in the hydrocarbon phase was relatively large.
Both CN100575320C and CN100383096C disclose methods for extracting oxygenates from hydrocarbon streamsUsing a mixture of methanol and water as solvent, but the process is only for C10-C13The oxygenate is removed from the stream of (a).
WO9958625 discloses a process for removing oxygenate impurities from a hydrocarbon stream using a light polar solvent formed from an acetonitrile/water solvent. But the method is only for C8-C10The oxygenate is removed from the stream of (a).
US4686317 discloses a process for removing light hydrocarbons (C)2To C9) A process for the extraction of oxygenates from a hydrocarbon stream comprising extracting the oxygenates with a heavy oil polar solvent such as propylene carbonate and 2-ethanolamine, washing the extracted hydrocarbon stream with water to recover dissolved solvent and combining the extracted solvent phase with an aqueous phase in a scrubber for the recovery of the solvent by distillation. But the method is only for C2-C9The oxygenate is removed from the stream of (a).
The alpha-olefin content in the Fischer-Tropsch synthesis product light oil and the heavy oil is higher, and the alpha-olefins with different distillation ranges have different purposes, so that the deoxidation technology of the whole fractions of the Fischer-Tropsch light oil and the heavy oil needs to be developed, but in the prior art, the alpha-olefin content is difficult to maintain by adopting a hydrodeoxygenation method; in the methods of adsorption and extraction, some methods only perform separation of oxygen-containing compounds on a hydrocarbon stream with a narrow distillation range, and have poor separation effect on the hydrocarbon stream with a wide distillation range, even if deoxygenation refining is performed on the hydrocarbon stream with the wide distillation range, the residual amount of the oxygen-containing compounds in the hydrocarbon phase is often large, the subsequent utilization of olefin cannot be ensured, and the oil yield needs to be improved. Moreover, the prior art mostly only performs separation and extraction on alcohol in the hydrocarbon stream, but does not perform separation on ketone, aldehyde, acid and ester in the hydrocarbon stream.
Disclosure of Invention
The invention aims to overcome the problems that the content of alpha-olefin is difficult to maintain, the separation effect of oxygen-containing compounds is poor, the separation of ketone, aldehyde, acid and ester in hydrocarbon material flow is not performed, and the yield of oil products is to be improved in the prior art, and provides a method for removing the oxygen-containing compounds from Fischer-Tropsch synthetic oil.
In order to achieve the above object, the first aspect of the present invention provides a method for removing oxygenates from fischer-tropsch synthesis oil, wherein the method comprises the following steps:
(1) carrying out atmospheric and vacuum fractionation on Fischer-Tropsch synthetic oil to obtain a first-stage fraction, a second-stage fraction and a third-stage fraction, wherein,
the distillation range of the first-stage fraction is IBP-TaThe temperature is less than or equal to 140 ℃ and T is less than or equal toa≤170℃；
The distillation range of the second-stage fraction is more than TaAnd is not more than TbThe temperature is less than or equal to 240 ℃ and T is less than or equal tob≤300℃；
The distillation range of the third-stage fraction is more than Tb℃；
(2) Carrying out first extraction on the first-stage fraction by using a methanol aqueous solution to obtain an extract phase 1 and a raffinate phase 1; performing second extraction on the second-stage fraction by using a first ethanol aqueous solution to obtain an extract phase 2 and a raffinate phase 2; performing third extraction on the third-stage fraction by using a second ethanol aqueous solution to obtain an extract phase 3 and a raffinate phase 3;
(3) washing the raffinate phase 1, the raffinate phase 2 and the raffinate phase 3 respectively to obtain deoxidized and refined Fischer-Tropsch synthetic oil;
the Fischer-Tropsch synthetic oil comprises 0.1-10 wt% of oxygen-containing compounds by total weight of the Fischer-Tropsch synthetic oil, wherein the oxygen-containing compounds comprise alcohols, ketones, aldehydes, acids and esters.
Preferably, in step (1), the distillation range of the first-stage fraction is IBP-TaFraction at 150 ℃ or lower, wherein T is not more than 150 ℃aLess than or equal to 160 ℃; the distillation range of the second-stage fraction is more than TaAnd is not more than TbThe temperature is less than or equal to 260 ℃ and T is more than or equal tobLess than or equal to 280 ℃; the distillation range of the third-stage fraction is more than Tb℃。
Preferably, in the step (2), the concentration of the methanol aqueous solution is not more than 85 wt%, preferably 60 to 75 wt%; the amount of the methanol aqueous solution is 0.5-4 times of the weight of the first-stage distillate, and preferably 0.8-2 times of the weight of the first-stage distillate.
Preferably, in the step (2), the concentration of the first ethanol aqueous solution is not more than 80 wt%, preferably 60-75 wt%; the dosage of the first ethanol water solution is 0.5-4 times of the weight of the second-stage distillate, and preferably 0.8-2 times.
Preferably, in the step (2), the concentration of the second ethanol aqueous solution is not more than 90 wt%, preferably 75-85 wt%; the dosage of the second ethanol aqueous solution is 0.5-4 times of the weight of the third section fraction, and preferably 0.8-2 times.
Preferably, the distillation range of the Fischer-Tropsch synthetic oil is IBP-380 ℃, and preferably IBP-350 ℃.
The invention carries out atmospheric and vacuum fractionation on Fischer-Tropsch synthetic oil to obtain three-section fractions, and then extracts the three-section fractions respectively, wherein the distillation range is IBP-TaFraction at 140 deg.C or less, Ta170 ℃ or less, preferably 150 ℃ or less TaExtracting with methanol water solution at 160 deg.C or below; for distillation range greater than TaAnd is not more than TbFraction at 240 ℃ or lower, TbLess than or equal to 300 ℃, preferably less than or equal to 260 ℃ and less than or equal to TbLess than or equal to 280 ℃ and the distillation range is more than TbThe fractions at the temperature are extracted by adopting an ethanol water solution respectively, the method not only keeps the α -olefin content in the Fischer-Tropsch synthetic oil, but also can effectively remove alcohol, ketone, aldehyde, acid and ester in the Fischer-Tropsch synthetic oil, the content of oxygen-containing compounds in the deoxidized and refined Fischer-Tropsch synthetic oil is reduced to be below 100ppm, and the oil recovery rate is high.
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FIG. 1 is a schematic diagram of the process for removing oxygenates from Fischer-Tropsch synthesis oil according to the present invention.
Detailed Description
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
In a first aspect, the present invention provides a process for removing oxygenates from fischer-tropsch synthesis oil, wherein the process comprises the steps of:
(1) carrying out atmospheric and vacuum fractionation on Fischer-Tropsch synthetic oil to obtain a first-stage fraction, a second-stage fraction and a third-stage fraction, wherein,
the distillation range of the first-stage fraction is IBP-TaThe temperature is less than or equal to 140 ℃ and T is less than or equal toa≤170℃；
The distillation range of the second-stage fraction is more than TaAnd is not more than TbThe temperature is less than or equal to 240 ℃ and T is less than or equal tob≤300℃；
The distillation range of the third-stage fraction is more than Tb℃；
(2) Carrying out first extraction on the first-stage fraction by using a methanol aqueous solution to obtain an extract phase 1 and a raffinate phase 1; performing second extraction on the second-stage fraction by using a first ethanol aqueous solution to obtain an extract phase 2 and a raffinate phase 2; performing third extraction on the third-stage fraction by using a second ethanol aqueous solution to obtain an extract phase 3 and a raffinate phase 3;
(3) washing the raffinate phase 1, the raffinate phase 2 and the raffinate phase 3 respectively to obtain deoxidized and refined Fischer-Tropsch synthetic oil;
the Fischer-Tropsch synthetic oil comprises 0.1-10 wt% of oxygen-containing compounds by total weight of the Fischer-Tropsch synthetic oil, wherein the oxygen-containing compounds comprise alcohols, ketones, aldehydes, acids and esters.
In the present invention, TaIt means the final distillation point of the first stage fraction, and can be 140-170 deg.C, TbThe final distillation point of the second stage fraction can be 240-300 ℃, and corresponding fractionation can be carried out according to different Fischer-Tropsch synthetic oils because the components of different Fischer-Tropsch synthetic oils are different, so that the final distillation temperature is TaFor example, TaCan be 140 deg.C and 145 deg.C150 ℃, 155 ℃, 160 ℃, 165 ℃, 170 ℃ and any value in the range of any two of these values.
In the invention, the Fischer-Tropsch synthetic oil comes from light oil and heavy oil fractions in the Fischer-Tropsch synthetic reaction process, and the composition of the Fischer-Tropsch synthetic oil can contain alkane, olefin and oxygen-containing compounds.
In the present invention, the term "IBP" refers to the initial boiling point, i.e. the temperature recorded at the instant when the first drop of condensate falls from the end of the condenser when the distillation range of the oil is measured.
In the present invention, the raffinate phase 1, the raffinate phase 2, and the raffinate phase 3 are each washed with water to obtain a hydrocarbon phase 1, a hydrocarbon phase 2, and a hydrocarbon phase 3, and the hydrocarbon phase 1, the hydrocarbon phase 2, and the hydrocarbon phase 3 are collectively referred to as a deoxygenated and purified fischer-tropsch synthetic oil. That is, the deoxygenated refined Fischer-Tropsch oil comprises a hydrocarbon phase 1, a hydrocarbon phase 2, and a hydrocarbon phase 3.
In the present invention, the atmospheric and vacuum fractionation may be a method conventionally used in the art, and the pressure and temperature of the atmospheric and vacuum fractionation are not particularly limited so as to obtain the distillation range IBP to T of the present inventionaDEG C and above TaAnd is not more than TbDEG C and greater than TbThe fraction at C was used for the purpose.
According to a preferred process of the invention, in step (1), the distillation range of the first-stage fraction is IBP-TaThe temperature is less than or equal to 150 ℃ and T is more than or equal toaLess than or equal to 160 ℃; the distillation range of the second-stage fraction is more than TaAnd is not more than TbThe temperature is less than or equal to 260 ℃ and T is more than or equal tobLess than or equal to 280 ℃; the distillation range of the third-stage fraction is more than Tb℃。TaIt means the final distillation point of the first stage fraction, and can be 150-160 deg.C, TbThe final distillation point of the second stage fraction can be 260-280 ℃, and corresponding fractionation can be carried out according to different Fischer-Tropsch synthetic oils because the components of different Fischer-Tropsch synthetic oils are different, so that the final distillation temperature is TaFor example, TaThe temperature may be 150 ℃, 151 ℃, 152 ℃, 153 ℃, 154 ℃, 155 ℃, 156 ℃, 157 ℃, 158 ℃, 159 ℃, 160 ℃ or any value in the range of any two of these values.
According to the method of the present invention, in the step (2), the concentration of the aqueous methanol solution may be not more than 85% by weight, and specifically, the content of methanol in the aqueous methanol solution may be not more than 85% by weight based on the total weight of the aqueous methanol solution. Preferably, the concentration of the aqueous methanol solution is 60 to 75 wt%, for example, 60 wt%, 65 wt%, 70 wt%, 75 wt%, and any value in the range of any two of these values.
According to the method of the present invention, in the step (2), the amount of the aqueous methanol solution may be 0.5 to 4 times, preferably 0.8 to 2 times, for example, 0.8 times, 0.9 times, 1 time, 1.1 times, 1.2 times, 1.3 times, 1.4 times, 1.5 times, 1.6 times, 1.7 times, 1.8 times, 1.9 times, 2 times, and any value in the range of any two of these values, based on the weight of the first stage fraction.
According to the method of the present invention, in the step (2), the concentration of the first aqueous ethanol solution may be not more than 80% by weight, and specifically, the content of ethanol in the first aqueous ethanol solution may be not more than 80% by weight, based on the total weight of the first aqueous ethanol solution. Preferably, the concentration of the first aqueous ethanol solution is 60 to 75 wt%, for example, 60 wt%, 65 wt%, 70 wt%, 75 wt%, and any value in the range of any two of these values.
According to the process of the present invention, the first aqueous ethanol solution may be used in an amount of 0.5 to 4 times, preferably 0.8 to 2 times, for example, 0.8 times, 0.9 times, 1 time, 1.1 times, 1.2 times, 1.3 times, 1.4 times, 1.5 times, 1.6 times, 1.7 times, 1.8 times, 1.9 times, 2 times, and any value in the range of any two of these values, based on the weight of the second stage fraction.
According to the method of the present invention, in the step (2), the concentration of the second aqueous solution of ethanol may be not more than 90% by weight, and specifically, the content of ethanol in the second aqueous solution of ethanol may be not more than 90% by weight based on the total weight of the second aqueous solution of ethanol. Preferably, the concentration of the second aqueous solution of ethanol is 75 to 85 wt%, for example, 75 wt%, 80 wt%, 85 wt%, and any value in the range of any two of these values.
According to the method of the present invention, the second ethanol aqueous solution may be used in an amount of 0.5 to 4 times, preferably 0.8 to 2 times, for example, 0.8 times, 0.9 times, 1 time, 1.1 times, 1.2 times, 1.3 times, 1.4 times, 1.5 times, 1.6 times, 1.7 times, 1.8 times, 1.9 times, 2 times, and any value in a range of any two of these values, based on the weight of the third fraction.
According to the method, the temperature of the first extraction can be 15-50 ℃, and preferably 20-50 ℃; the first extraction method can be a multi-stage countercurrent extraction method; the theoretical stage number of the first extraction can be 3-10 stages, and preferably 5-7 stages.
According to the method, the temperature of the second extraction can be 15-50 ℃, and preferably 20-50 ℃; the second extraction method can be a multi-stage countercurrent extraction method; the theoretical stage number of the second extraction can be 3-10 stages, and preferably 5-7 stages.
According to the method, the temperature of the third extraction can be 15-50 ℃, and preferably 20-50 ℃; the third extraction method can be a multi-stage countercurrent extraction method; the theoretical stage number of the third extraction can be 3-10 stages, and preferably 5-7 stages.
According to the method, the fraction distribution of the Fischer-Tropsch synthetic oil is wide, the heavier the fraction in the Fischer-Tropsch synthetic oil is, the lower the olefin content in the oil product is, the higher the alkane content is, the lower the oxygen-containing compound content is, and the olefin content of the fraction at the temperature of more than 380 ℃ is lower, so that before extraction, the Fischer-Tropsch synthetic oil is fractionated, the distillation range of the obtained Fischer-Tropsch synthetic oil is IBP-380 ℃, and the IBP-350 ℃ is preferably obtained.
According to the method, the method further comprises the step of carrying out solvent separation on the extraction phase 1, the extraction phase 2 and the extraction phase 3 respectively to obtain an oxygen-containing compound and a circulating solvent, wherein the oxygen-containing compound refers to the organic phase 1, the organic phase 2 and the organic phase 3 in the figure 1, and the circulating solvent refers to a recyclable solvent. Specifically, taking the extraction phase 1 as an example, introducing the extraction phase 1 into a first rectification tower, obtaining methanol at the tower top of the first rectification tower, introducing a kettle bottom product of the first rectification tower into a first decanter, recovering an aqueous solvent at the bottom of the first decanter, and preparing the aqueous solution with the methanol obtained at the tower top of the first rectification tower to obtain a methanol aqueous solution with a required concentration, returning the aqueous solution to the first extraction tower for recycling as a circulating solvent, and obtaining an organic phase 1 at the top of the first decanter, wherein the organic phase 1 contains an oxygen-containing compound, olefin and paraffin stream.
According to the process of the present invention, the raffinate 1, raffinate 2 and raffinate 3 comprise a small amount of solvent alcohol (raffinate 1 comprises methanol and raffinate 2 and raffinate 3 each comprise ethanol), and thus the raffinate 1, raffinate 2 and raffinate 3 are introduced into respective water wash columns. Taking raffinate phase 1 as an example, introducing raffinate phase 1 into a first water washing tower, washing methanol by a water washing method, leading out a hydrocarbon phase as a tower top product to obtain a hydrocarbon phase 1, and returning a tower bottom product to the first extraction tower for recycling.
According to the method, the content of the oxygen-containing compound in the deoxidized and refined Fischer-Tropsch synthetic oil can reach less than 100ppm (0.01 wt%), preferably less than 50 ppm; the recovery of olefins and paraffins is higher than 95% by weight, and preferably may be higher than 98% by weight.
According to one embodiment of the present invention, as shown in FIG. 1, the method for removing oxygenates from Fischer-Tropsch synthesis oil comprises the following steps:
(1) carrying out atmospheric and vacuum fractionation on Fischer-Tropsch synthetic oil to obtain a first-stage fraction, a second-stage fraction and a third-stage fraction, wherein the distillation range of the first-stage fraction is IBP-TaThe temperature is less than or equal to 140 ℃ and T is less than or equal toaLess than or equal to 170 ℃; the distillation range of the second-stage fraction is more than TaAnd is not more than TbThe temperature is less than or equal to 240 ℃ and T is less than or equal tobLess than or equal to 300 ℃; the distillation range of the third-stage fraction is more than Tb℃；
(2) And carrying out first extraction on the first section of fraction by using a methanol aqueous solution to obtain an extract phase 1 and a raffinate phase 1. The first fraction is fed into the first extraction column at or near the bottom of the column, and an extractant 1 comprising an aqueous methanol solution having a concentration of not more than 85% by weight, preferably 60 to 75% by weight, is fed into the first extraction column at or near the top of the column. And introducing a raffinate phase 1 at the top of the first extraction tower into a first water washing tower, wherein the raffinate phase 1 contains olefin, paraffin and a small amount of methanol. The methanol is washed away by a water washing method, a hydrocarbon phase 1 is taken out as a first water washing tower top product, a first water washing tower bottom product (methanol water solution) is returned to the first extraction tower for recycling, and the hydrocarbon phase 1 comprises more than 99 weight percent of olefin and paraffin (the content of alpha-olefin is more than 60 weight percent, and the content of n-paraffin is more than 20 weight percent) and less than 100ppm (0.01 weight percent) of oxygenated compounds, preferably less than 50ppm (0.005 weight percent) of oxygenated compounds. Extract phase 1 from the bottom of the first extraction column is introduced into a first rectification column, the overhead product from which contains more than 95 wt% methanol and small amounts of olefins and paraffins. More than 80 wt% of the olefins and paraffins in extract phase 1 are recovered in the first rectifier overhead. The method comprises the following steps of (1) obtaining methanol from the top of a first rectifying tower, introducing a kettle bottom product of the first rectifying tower into a first decanter, recovering a water solvent from the bottom of the first decanter, preparing the water solvent with the methanol obtained from the top of the first rectifying tower to obtain a methanol water solution with required concentration, returning the methanol water solution to a first extraction tower for recycling, and obtaining an organic phase 1 from the top of the first decanter, wherein the organic phase 1 contains an oxygen-containing compound, olefin and paraffin flow;
and carrying out second extraction on the second-stage fraction by using a first ethanol aqueous solution to obtain an extract phase 2 and a raffinate phase 2. The second-stage fraction is conveyed into the second extraction tower at the bottom or close to the bottom of the second extraction tower, and the extracting agent 2 containing the ethanol aqueous solution is conveyed into the second extraction tower at the top or close to the top of the second extraction tower, wherein the concentration of the ethanol aqueous solution is not more than 80 wt%, and preferably 60-75 wt%. And introducing a raffinate phase 2 at the top of the second extraction tower into a second water washing tower, wherein the raffinate phase 2 contains olefin, paraffin and a small amount of ethanol. The ethanol is washed away by a water washing method, and a hydrocarbon phase 2 is taken out as a second water washing tower top product, a second water washing tower bottom product (ethanol water solution) is returned to a second extraction tower for recycling, wherein the hydrocarbon phase 2 comprises more than 99 weight percent of olefin and paraffin (the content of alpha-olefin is more than 50 weight percent, and the content of n-paraffin is more than 30 weight percent) and less than 100ppm (0.01 weight percent) of oxygenated compounds, preferably less than 50ppm (0.005 weight percent) of oxygenated compounds. The extract phase 2 from the bottom of the second extraction column is introduced into a second rectification column, the overhead product from which contains more than 90 wt% of an azeotrope of ethanol and water, and small amounts of olefins and paraffins. More than 80 wt% of the olefins and paraffins in extract phase 2 are recovered in the second rectification column overhead product. The top of the second rectifying tower obtains ethanol or an azeotrope of ethanol and water, the bottom product of the second rectifying tower is introduced into a second decanter, the bottom of the second decanter recovers water solvent and is prepared with the ethanol or the azeotrope of ethanol and water obtained from the top of the second rectifying tower to obtain ethanol water solution with required concentration, the ethanol water solution returns to the second extraction tower for recycling, and the top of the second decanter obtains an organic phase 2, wherein the organic phase 2 contains oxygen-containing compounds, olefin and paraffin flow;
and carrying out third extraction on the third-stage fraction by using a second ethanol aqueous solution to obtain an extract phase 3 and a raffinate phase 3. The third section fraction is conveyed into the third extraction tower at the bottom or close to the bottom of the third extraction tower, and the extracting agent 3 containing the ethanol aqueous solution is conveyed into the third extraction tower at the top or close to the top of the third extraction tower, wherein the concentration of the ethanol aqueous solution is not more than 90 wt%, and preferably 75-85 wt%. And introducing a raffinate phase 3 at the top of the third extraction tower into a third water washing tower, wherein the raffinate phase 3 contains olefin, paraffin and a small amount of ethanol. The ethanol is washed away by a water washing method, a hydrocarbon phase 3 is taken out as a third water washing tower top product, a third water washing tower bottom product (ethanol water solution) is returned to a third extraction tower for recycling, and the hydrocarbon phase 3 comprises more than 99 weight percent of olefin and paraffin (the content of alpha-olefin is more than 40 weight percent, and the content of n-paraffin is more than 40 weight percent) and less than 100ppm (0.01 weight percent) of oxygenated compounds, preferably less than 50ppm (0.005 weight percent) of oxygenated compounds. The extract phase 3 at the bottom of the third extraction column is introduced into a third rectification column, the overhead product from which contains more than 90% by weight of ethanol and small amounts of olefins and paraffins. More than 80 wt% of the olefins and paraffins in extract phase 3 are recovered in the third rectification column overhead product. And (2) obtaining ethanol or an azeotrope of ethanol and water at the top of the third rectifying tower, introducing a kettle bottom product of the third rectifying tower into a third decanter, recovering a water solvent at the bottom of the third decanter, preparing the water solvent with the ethanol or the azeotrope of ethanol and water obtained at the top of the third rectifying tower to obtain an ethanol water solution with required concentration, returning the ethanol water solution to the third extraction tower for recycling, and obtaining an organic phase 3 at the top of the third decanter, wherein the organic phase 3 contains an oxygen-containing compound, olefin and paraffin stream.
The present invention will be described in detail below by way of examples.
The composition and content of the Fischer-Tropsch synthetic oil are shown in Table 1.
TABLE 1
Composition (I) α -olefins N-alkanes Alcohol(s) Aldehydes and ketones Acids and esters
Content by weight% 60.26 31.69 3.16 0.64 0.12
Example 1
As shown in FIG. 1, the Fischer-Tropsch synthesis oil shown in Table 1 was subjected to atmospheric and vacuum fractionation to obtain a first stage fraction, a second stage fraction and a third stage fraction, wherein,
the distillation range of the first-stage fraction is 59-160 ℃, wherein the content of alpha-olefin is 71.29 wt%, the content of normal alkane is 22.02 wt%, the content of alcohol in the oxygen-containing compound is 2.60 wt%, the content of aldehyde and ketone is 0.62 wt%, and the content of acid and ester is 0.14 wt%;
the second stage fraction had a distillation range of more than 160 ℃ and not more than 280 ℃, and contained 67.21 wt% of α -olefin, 25.32 wt% of n-alkane, 3.56 wt% of alcohol in the oxygen-containing compound, 0.74 wt% of aldehyde and ketone, and 0.11 wt% of acid and ester;
the distillation range of the third stage fraction is a fraction of more than 280 ℃ and not more than 350 ℃, wherein the content of alpha-olefin is 45.32 wt%, the content of normal alkane is 45.54 wt%, the content of alcohol in the oxygen-containing compound is 3.35 wt%, the content of aldehyde and ketone is 0.52 wt%, and the content of acid and ester is 0.10 wt%;
(2) taking 1000g of the first-stage fraction, and carrying out multi-stage countercurrent extraction in a first extraction tower by using a 65 wt% methanol aqueous solution, wherein the extraction temperature is 20 ℃, the dosage of the methanol aqueous solution is 1000g, and the extraction theoretical stage number is 7, so as to obtain an extract phase 1 and a raffinate phase 1. Introducing raffinate phase 1 at the top of the first extraction tower into a first water washing tower, washing methanol off by a water washing method, taking out hydrocarbon phase 1 as a tower top product, returning a tower bottom product (methanol aqueous solution) to the first extraction tower for recycling, and obtaining 947.1g of hydrocarbon phase 1, wherein the recovery rate of the hydrocarbon phase 1 is 98.0%, the alpha-olefin content in the hydrocarbon phase 1 is 72.30 wt%, the normal alkane content is 23.21 wt%, and the oxygen-containing compound content is 70ppm (the alcohol content is 0ppm, the aldehyde and ketone content is 52ppm, and the acid and ester content is 18ppm) through gas chromatography detection. Introducing an extract phase 1 at the bottom of a first extraction tower into a first rectifying tower, obtaining methanol at the top of the first rectifying tower, introducing a kettle bottom product of the first rectifying tower into a first decanter, recovering an aqueous solvent at the bottom of the first decanter, preparing the aqueous solvent and the methanol obtained at the top of the first rectifying tower to obtain a 65 wt% methanol aqueous solution, returning the aqueous solution to the first extraction tower for recycling, and obtaining an organic phase 1 at the top of the first decanter;
and taking 1000g of the second-stage fraction, and carrying out multi-stage countercurrent extraction in a second extraction tower by using 69 wt% ethanol aqueous solution at the extraction temperature of 20 ℃, wherein the dosage of the ethanol aqueous solution is 1000g, and the extraction theoretical stage number is 7, so as to obtain an extract phase 2 and a raffinate phase 2. Introducing the raffinate phase 2 at the top of the second extraction tower into a second water washing tower, washing off ethanol by a water washing method, taking out the hydrocarbon phase 2 as a tower top product, returning a tower bottom product (ethanol aqueous solution) to the second extraction tower for recycling to obtain 941.6g of the hydrocarbon phase 2, wherein the recovery rate of the hydrocarbon phase 2 is 98.5%, and the alpha-olefin content in the hydrocarbon phase 2 is 68.13% by weight, the normal alkane content is 26.43% by weight and the oxygen-containing compound content is 68ppm (the alcohol content is 0ppm, the aldehyde content and the ketone content is 54ppm, and the acid content and the ester content are 14ppm) through gas chromatography detection. Introducing an extraction phase 2 at the bottom of a second extraction tower into a second rectifying tower, obtaining an azeotrope of ethanol and water at the top of the second rectifying tower, introducing a kettle bottom product of the second rectifying tower into a second decanter, recovering a water solvent at the bottom of the second decanter, preparing the azeotrope of ethanol and water obtained at the top of the second rectifying tower with the water solvent to obtain an ethanol aqueous solution with the concentration of 69 weight percent, returning the ethanol aqueous solution to the second extraction tower for recycling, and obtaining an organic phase 2 at the top of the second decanter;
and taking 1000g of the third-stage fraction, and carrying out multi-stage countercurrent extraction in a third extraction tower by using 80 wt% ethanol aqueous solution, wherein the extraction temperature is 20 ℃, the dosage of an extractant is 1000g, and the extraction theoretical stage number is 7, so as to obtain an extract phase 3 and a raffinate phase 3. Introducing a raffinate phase 3 at the top of the third extraction tower into a third water washing tower, washing off ethanol by a water washing method, taking out the hydrocarbon phase 3 as a tower top product, returning a tower bottom product (ethanol aqueous solution) to the third extraction tower for recycling to obtain 948.8g of the hydrocarbon phase 3, wherein the recovery rate of the hydrocarbon phase 3 is 98.8%, and the alpha-olefin content, the normal alkane content and the oxygen-containing compound content in the hydrocarbon phase 3 are respectively 46.21 wt%, 46.16 wt% and 80ppm (the alcohol content is 0ppm, the aldehyde content and the ketone content is 60ppm, and the acid content and the ester content are 20ppm) according to gas chromatography detection. Introducing an extraction phase 3 at the bottom of a third extraction tower into a third rectifying tower, obtaining an azeotrope of ethanol and water at the top of the third rectifying tower, introducing a kettle bottom product of the third rectifying tower into a third decanter, recovering an aqueous solvent at the bottom of the third decanter, preparing the aqueous solvent with the azeotrope of ethanol and water obtained at the top of the third rectifying tower to obtain an ethanol aqueous solution with the concentration of 80 weight percent, returning the aqueous solution to the third extraction tower for recycling, and obtaining an organic phase 3 at the top of the third decanter;
in summary, the content of the oxygen-containing compounds in the hydrocarbon phase 1, the hydrocarbon phase 2 and the hydrocarbon phase 3 is 70ppm, 68ppm and 80ppm, that is, the content of the oxygen-containing compounds in the deoxidized and refined Fischer-Tropsch synthesis oil is less than 100 ppm.
Example 2
The Fischer-Tropsch synthesis oil shown in the table 1 is subjected to atmospheric and vacuum fractionation to obtain a first stage fraction, a second stage fraction and a third stage fraction, wherein,
the distillation range of the first-stage fraction is 59-150 ℃, wherein the content of alpha-olefin is 72.12 wt%, the content of normal alkane is 21.32 wt%, the content of alcohol in the oxygen-containing compound is 2.54 wt%, the content of aldehyde and ketone is 0.60 wt%, and the content of acid and ester is 0.14 wt%;
the second stage fraction had a distillation range of greater than 150 ℃ and not greater than 260 ℃ and contained 68.01 wt% of α -olefin, 24.52 wt% of n-alkane, 3.57 wt% of alcohol in the oxygen-containing compound, 0.75 wt% of aldehydes and ketones, and 0.12 wt% of acids and esters;
the distillation range of the third stage fraction is a fraction of more than 260 ℃ and not more than 350 ℃, wherein the content of alpha-olefin is 46.18 wt%, the content of normal alkane is 44.12 wt%, the content of alcohol in the oxygen-containing compound is 3.41 wt%, the content of aldehyde and ketone is 0.59 wt%, and the content of acid and ester is 0.10 wt%;
(2) and taking 1000g of the first-stage fraction, and carrying out multi-stage countercurrent extraction in a first extraction tower by using 75 wt% of methanol aqueous solution at the extraction temperature of 15 ℃, wherein the dosage of the methanol aqueous solution is 2000g, and the extraction theoretical stage number is 5, so as to obtain an extract phase 1 and a raffinate phase 1. Introducing a raffinate phase 1 at the top of the first extraction tower into a first water washing tower, washing methanol off by a water washing method, taking out a hydrocarbon phase 1 as a tower top product, returning a tower bottom product (a methanol aqueous solution) to the first extraction tower for recycling to obtain 941.1g of the hydrocarbon phase 1, wherein the recovery rate of the hydrocarbon phase 1 is 97.3%, and the alpha-olefin content in the hydrocarbon phase 1 is 72.98% by weight, the normal alkane content is 22.13% by weight and the oxygen-containing compound content is 45ppm (the alcohol content is 0ppm, the aldehyde and ketone content is 37ppm, and the acid and ester content is 8ppm) through gas chromatography detection. Introducing an extraction phase 1 at the bottom of a first extraction tower into a first rectifying tower, obtaining methanol at the top of the first rectifying tower, introducing a kettle bottom product of the first rectifying tower into a first decanter, recovering an aqueous solvent at the bottom of the first decanter, preparing the aqueous solvent and the methanol obtained at the top of the first rectifying tower to obtain a 75 wt% methanol aqueous solution, returning the aqueous solution to the first extraction tower for recycling, and obtaining an organic phase 1 at the top of the first decanter;
and taking 1000g of the second-stage fraction, and carrying out multi-stage countercurrent extraction in a second extraction tower by using 75 wt% ethanol aqueous solution at the extraction temperature of 15 ℃, the dosage of the ethanol aqueous solution of 2000g and the extraction theoretical stage number of 5 to obtain an extract phase 2 and a raffinate phase 2. Introducing the raffinate phase 2 at the top of the second extraction tower into a second water washing tower, washing off ethanol by a water washing method, taking out the hydrocarbon phase 2 as a tower top product, returning a tower bottom product (ethanol aqueous solution) to the second extraction tower for recycling to obtain 936.5g of the hydrocarbon phase 2, wherein the recovery rate of the hydrocarbon phase 2 is 98.0%, and the alpha-olefin content in the hydrocarbon phase 2 is 68.91% by weight, the normal alkane content is 25.36% by weight, and the oxygen-containing compound content is 43ppm (the alcohol content is 0ppm, the aldehyde and ketone content is 32ppm, and the acid and ester content is 11ppm) through gas chromatography detection. Introducing an extraction phase 2 at the bottom of a second extraction tower into a second rectification tower, obtaining an azeotrope of ethanol and water at the top of the second rectification tower, introducing a kettle bottom product of the second rectification tower into a second decanter, recovering a water solvent at the bottom of the second decanter, preparing the azeotrope of ethanol and water obtained at the top of the second rectification tower with the water solvent to obtain an ethanol aqueous solution with the concentration of 75 weight percent, returning the ethanol aqueous solution to the second extraction tower for recycling, and obtaining an organic phase 2 at the top of the second decanter;
and taking 1000g of the third-stage fraction, and carrying out multi-stage countercurrent extraction in a third extraction tower by using 85 wt% ethanol aqueous solution, wherein the extraction temperature is 15 ℃, the dosage of an extractant is 2000g, and the extraction theoretical stage number is 5, so as to obtain an extract phase 3 and a raffinate phase 3. Introducing a raffinate phase 3 at the top of the third extraction tower into a third water washing tower, washing off ethanol by a water washing method, taking out the hydrocarbon phase 3 as a tower top product, returning a tower bottom product (ethanol aqueous solution) to the third extraction tower for recycling to obtain 941.7g of the hydrocarbon phase 3, wherein the recovery rate of the hydrocarbon phase 3 is 98.2%, and the alpha-olefin content in the hydrocarbon phase 3 is 47.28% by weight, the normal alkane content is 45.32% by weight, and the oxygen-containing compound content is 42ppm (the alcohol content is 0ppm, the aldehyde and ketone content is 31ppm, and the acid and ester content is 11ppm) through gas chromatography detection. Introducing an extraction phase 3 at the bottom of a third extraction tower into a third rectifying tower, obtaining an azeotrope of ethanol and water at the top of the third rectifying tower, introducing a kettle bottom product of the third rectifying tower into a third decanter, recovering a water solvent at the bottom of the third decanter, preparing the water solvent with the azeotrope of ethanol and water obtained at the top of the third rectifying tower to obtain an ethanol water solution with the concentration of 85 weight percent, returning the ethanol water solution to the third extraction tower for recycling, and obtaining an organic phase 3 at the top of the third decanter;
in summary, the content of the oxygen-containing compounds in the hydrocarbon phase 1, the hydrocarbon phase 2 and the hydrocarbon phase 3 is divided into 45ppm, 43ppm and 42ppm, that is, the content of the oxygen-containing compounds in the deoxygenated refined Fischer-Tropsch synthesis oil is less than 100 ppm.
Example 3
The Fischer-Tropsch synthesis oil shown in the table 1 is subjected to atmospheric and vacuum fractionation to obtain a first stage fraction, a second stage fraction and a third stage fraction, wherein,
the distillation range of the first-stage fraction is 59-170 ℃, wherein the content of alpha-olefin is 70.97 wt%, the content of normal alkane is 23.02 wt%, the content of alcohol in the oxygen-containing compound is 2.61 wt%, the content of aldehyde and ketone is 0.64 wt%, and the content of acid and ester is 0.14 wt%;
the second stage fraction had a distillation range of more than 170 ℃ and not more than 300 ℃, and contained 62.69 wt% of α -olefin, 29.24 wt% of n-alkane, 3.54 wt% of alcohol in the oxygen-containing compound, 0.71 wt% of aldehyde and ketone, and 0.11 wt% of acid and ester;
the distillation range of the third stage fraction is a fraction of more than 300 ℃ and not more than 380 ℃, wherein the content of alpha-olefin is 40.46 wt%, the content of normal alkane is 48.91 wt%, the content of alcohol in the oxygen-containing compound is 3.21 wt%, the content of aldehyde and ketone is 0.51 wt%, and the content of acid and ester is 0.08 wt%; (ii) a
(2) And taking 1000g of the first-stage fraction, and carrying out multistage countercurrent extraction in a first extraction tower by using 60 wt% methanol aqueous solution at the extraction temperature of 50 ℃, wherein the dosage of the methanol aqueous solution is 500g, and the extraction theoretical stage number is 10, so as to obtain an extract phase 1 and a raffinate phase 1. Introducing raffinate phase 1 at the top of the first extraction tower into a first water washing tower, washing methanol off by a water washing method, taking out hydrocarbon phase 1 as a tower top product, returning a tower bottom product (methanol aqueous solution) to the first extraction tower for recycling, and obtaining 947.7g of hydrocarbon phase 1, wherein the recovery rate of the hydrocarbon phase 1 is 98.1%, the alpha-olefin content in the hydrocarbon phase 1 is 72.1 wt%, the normal alkane content is 23.6 wt%, and the oxygen-containing compound content is 80ppm (the alcohol content is 0ppm, the aldehyde and ketone content is 62ppm, and the acid and ester content is 18ppm) through gas chromatography detection. Introducing an extract phase 1 at the bottom of a first extraction tower into a first rectifying tower, obtaining methanol at the top of the first rectifying tower, introducing a kettle bottom product of the first rectifying tower into a first decanter, recovering an aqueous solvent at the bottom of the first decanter, preparing the aqueous solvent and the methanol obtained at the top of the first rectifying tower to obtain a 60 wt% methanol aqueous solution, returning the aqueous solution to the first extraction tower for recycling, and obtaining an organic phase 1 at the top of the first decanter;
and taking 1000g of the second-stage fraction, and carrying out multi-stage countercurrent extraction in a second extraction tower by using 60 wt% ethanol aqueous solution at the extraction temperature of 50 ℃, wherein the dosage of the ethanol aqueous solution is 500g, and the extraction theoretical stage number is 10, so as to obtain an extract phase 2 and a raffinate phase 2. Introducing the raffinate phase 2 at the top of the second extraction tower into a second water washing tower, washing off ethanol by a water washing method, taking out the hydrocarbon phase 2 as a tower top product, returning a tower bottom product (ethanol aqueous solution) to the second extraction tower for recycling to obtain 941.1g of the hydrocarbon phase 2, wherein the recovery rate of the hydrocarbon phase 2 is 98.4%, and the alpha-olefin content, the normal alkane content and the oxygen-containing compound content in the hydrocarbon phase 2 are respectively 65.1 wt%, 31.1 wt% and 85ppm (the alcohol content, the aldehyde content and the ketone content and the acid content and the ester content are respectively 20ppm) through gas chromatography detection. Introducing an extraction phase 2 at the bottom of a second extraction tower into a second rectification tower, obtaining an azeotrope of ethanol and water at the top of the second rectification tower, introducing a kettle bottom product of the second rectification tower into a second decanter, recovering a water solvent at the bottom of the second decanter, preparing the azeotrope of ethanol and water obtained at the top of the second rectification tower with the water solvent to obtain an ethanol aqueous solution with the concentration of 60 weight percent, returning the ethanol aqueous solution to the second extraction tower for recycling, and obtaining an organic phase 2 at the top of the second decanter;
and taking 1000g of the third-stage fraction, and carrying out multi-stage countercurrent extraction in a third extraction tower by using 75 wt% ethanol aqueous solution, wherein the extraction temperature is 50 ℃, the dosage of an extractant is 500g, and the extraction theoretical stage number is 10, so as to obtain an extract phase 3 and a raffinate phase 3. Introducing a raffinate phase 3 at the top of the third extraction tower into a third water washing tower, washing off ethanol by a water washing method, taking out the hydrocarbon phase 3 as a tower top product, returning a tower bottom product (ethanol aqueous solution) to the third extraction tower for recycling to obtain 952.4g of the hydrocarbon phase 3, wherein the recovery rate of the hydrocarbon phase 3 is 99.0%, and the alpha-olefin content, the normal alkane content and the oxygen-containing compound content in the hydrocarbon phase 3 are respectively 41.2 wt%, 50.0 wt% and 89ppm (the alcohol content, the aldehyde content and the ketone content and the acid content and the ester content are respectively 22ppm) through gas chromatography detection. Introducing an extraction phase 3 at the bottom of a third extraction tower into a third rectifying tower, obtaining an azeotrope of ethanol and water at the top of the third rectifying tower, introducing a kettle bottom product of the third rectifying tower into a third decanter, recovering a water solvent at the bottom of the third decanter, preparing the water solvent with the azeotrope of ethanol and water obtained at the top of the third rectifying tower to obtain an ethanol water solution with the concentration of 75 weight percent, returning the ethanol water solution to the third extraction tower for recycling, and obtaining an organic phase 3 at the top of the third decanter;
in summary, the content of the oxygen-containing compounds in the hydrocarbon phase 1, the hydrocarbon phase 2 and the hydrocarbon phase 3 is respectively 80ppm, 85ppm and 89ppm, that is, the content of the oxygen-containing compounds in the deoxidized and refined Fischer-Tropsch synthesis oil is less than 100 ppm.
Example 4
The Fischer-Tropsch synthesis oil shown in the table 1 is subjected to atmospheric and vacuum fractionation to obtain a first stage fraction, a second stage fraction and a third stage fraction, wherein,
the distillation range of the first-stage fraction is 59-140 ℃, wherein the content of alpha-olefin is 72.96 wt%, the content of normal alkane is 22.01 wt%, the content of alcohol in the oxygen-containing compound is 2.44 wt%, the content of aldehyde and ketone is 0.59 wt%, and the content of acid and ester is 0.13 wt%;
the second stage fraction had a distillation range of greater than 140 ℃ and not greater than 240 ℃, wherein the content of α -olefin was 68.69% by weight, the content of n-alkane was 24.01% by weight, the content of alcohol in the oxygen-containing compound was 3.58% by weight, the content of aldehyde and ketone was 0.76% by weight, and the content of acid and ester was 0.13% by weight;
the distillation range of the third stage fraction is a fraction of more than 240 ℃ and not more than 380 ℃, wherein the content of alpha-olefin is 52.23 wt%, the content of normal alkane is 38.07 wt%, the content of alcohol in the oxygen-containing compound is 3.42 wt%, the content of aldehyde and ketone is 0.62 wt%, and the content of acid and ester is 0.11 wt%;
(2) taking 1000g of the first-stage fraction, and carrying out multi-stage countercurrent extraction in a first extraction tower by using 85 wt% methanol aqueous solution, wherein the extraction temperature is 30 ℃, the dosage of the methanol aqueous solution is 4000g, and the extraction theoretical stage number is 3, so as to obtain an extract phase 1 and a raffinate phase 1. Introducing raffinate phase 1 at the top of the first extraction tower into a first water washing tower, washing methanol off by a water washing method, taking out hydrocarbon phase 1 as a tower top product, returning a tower bottom product (methanol aqueous solution) to the first extraction tower for recycling, and obtaining 941.3g of hydrocarbon phase 1, wherein the recovery rate of the hydrocarbon phase 1 is 97.2%, the alpha-olefin content in the hydrocarbon phase 1 is 73.81 wt%, the normal alkane content is 23.21 wt%, and the oxygen-containing compound content is 70ppm (the alcohol content is 0ppm, the aldehyde and ketone content is 52ppm, and the acid and ester content is 18ppm) through gas chromatography detection. Introducing an extraction phase 1 at the bottom of a first extraction tower into a first rectifying tower, obtaining methanol at the top of the first rectifying tower, introducing a kettle bottom product of the first rectifying tower into a first decanter, recovering an aqueous solvent at the bottom of the first decanter, preparing the aqueous solvent and the methanol obtained at the top of the first rectifying tower to obtain a methanol aqueous solution with the concentration of 85 weight percent, returning the methanol aqueous solution to the first extraction tower for recycling, and obtaining an organic phase 1 at the top of the first decanter;
and taking 1000g of the second-stage fraction, and carrying out multi-stage countercurrent extraction in a second extraction tower by using 80 wt% ethanol aqueous solution at the extraction temperature of 30 ℃, wherein the dosage of the ethanol aqueous solution is 4000g, and the extraction theoretical stage number is 3, so as to obtain an extract phase 2 and a raffinate phase 2. Introducing the raffinate phase 2 at the top of the second extraction tower into a second water washing tower, washing off ethanol by a water washing method, taking out the hydrocarbon phase 2 as a tower top product, returning a tower bottom product (ethanol aqueous solution) to the second extraction tower for recycling to obtain 937.1g of the hydrocarbon phase 2, wherein the recovery rate of the hydrocarbon phase 2 is 98.1%, and the alpha-olefin content in the hydrocarbon phase 2 is 69.26% by weight, the normal alkane content is 24.96% by weight, and the oxygen-containing compound content is 73ppm (the alcohol content is 0ppm, the aldehyde and ketone content is 58ppm, and the acid and ester content is 15ppm) through gas chromatography detection. Introducing an extraction phase 2 at the bottom of a second extraction tower into a second rectification tower, obtaining an azeotrope of ethanol and water at the top of the second rectification tower, introducing a kettle bottom product of the second rectification tower into a second decanter, recovering a water solvent at the bottom of the second decanter, preparing the azeotrope of ethanol and water obtained at the top of the second rectification tower with the water solvent to obtain an ethanol aqueous solution with the concentration of 80 weight percent, returning the ethanol aqueous solution to the second extraction tower for recycling, and obtaining an organic phase 2 at the top of the second decanter;
and taking 1000g of the third-stage fraction, and performing multi-stage countercurrent extraction in a third extraction tower by using 90 wt% ethanol aqueous solution, wherein the extraction temperature is 30 ℃, the dosage of an extracting agent is 4000g, and the extraction theoretical stage is 3 stages, so that an extract phase 3 and a raffinate phase 3 are obtained. Introducing a raffinate phase 3 at the top of the third extraction tower into a third water washing tower, washing off ethanol by a water washing method, taking out the hydrocarbon phase 3 as a tower top product, returning a tower bottom product (ethanol aqueous solution) to the third extraction tower for recycling to obtain 940.3g of the hydrocarbon phase 3, wherein the recovery rate of the hydrocarbon phase 3 is 98.1%, and the alpha-olefin content in the hydrocarbon phase 3 is 53.06 wt%, the normal alkane content is 38.76 wt%, and the oxygen-containing compound content is 75ppm (the alcohol content is 0ppm, the aldehyde content and the ketone content is 61ppm, and the acid content and the ester content are 14ppm) through gas chromatography detection. Introducing an extraction phase 3 at the bottom of a third extraction tower into a third rectifying tower, obtaining an azeotrope of ethanol and water at the top of the third rectifying tower, introducing a kettle bottom product of the third rectifying tower into a third decanter, recovering an aqueous solvent at the bottom of the third decanter, preparing the aqueous solvent with the azeotrope of ethanol and water obtained at the top of the third rectifying tower to obtain an ethanol aqueous solution with the concentration of 90 weight percent, returning the aqueous solution to the third extraction tower for recycling, and obtaining an organic phase 3 at the top of the third decanter;
in summary, the content of the oxygen-containing compounds in the hydrocarbon phase 1, the hydrocarbon phase 2 and the hydrocarbon phase 3 is 70ppm, 73ppm and 75ppm, that is, the content of the oxygen-containing compounds in the deoxygenated refined Fischer-Tropsch synthesis oil is less than 100 ppm.
Comparative example 1
1000g of Fischer-Tropsch synthesis oil shown in the table 1 is taken, multi-stage countercurrent extraction is carried out by using 69% ethanol aqueous solution, the extraction temperature is 20 ℃, the dosage of an extracting agent is 1000g, the extraction theoretical stage is 7 stages, 873.0g of hydrocarbon phase 1 is obtained, the recovery rate of the hydrocarbon phase is 90.9%, and the alpha-olefin content, the normal alkane content and the oxygen-containing compound content in the hydrocarbon phase are respectively 61.9 wt%, 32.2 wt% and 200ppm (the alcohol content is 40ppm, the aldehyde content and the ketone content are 120ppm, and the acid content and the ester content are 40ppm) through gas chromatography detection.
Comparative example 2
1000g of Fischer-Tropsch synthesis oil shown in Table 1 was subjected to multistage countercurrent extraction with a 65% methanol aqueous solution at an extraction temperature of 20 ℃, an extractant amount of 1000g, and a theoretical stage number of extraction of 7, to obtain 953.1g of a hydrocarbon phase 1 having a recovery rate of 99.2%, and as determined by gas chromatography, the hydrocarbon phase had an α -olefin content of 61.8 wt%, a normal paraffin content of 32.3 wt%, and an oxygen-containing compound content of 900ppm (an alcohol content of 300ppm, aldehyde and ketone contents of 400ppm, and acid and ester contents of 200 ppm).
Comparative example 3
The process of example 1 was followed except that the aqueous methanol solution in step (2) was replaced with an aqueous ethanol solution. That is, 1000g of the first stage fraction was taken, and subjected to multistage countercurrent extraction with an aqueous ethanol solution having a concentration of 65% by weight in a first extraction column to obtain 869.8g of a hydrocarbon phase 1, the recovery rate of the hydrocarbon phase 1 was 90.0%, and the content of α -olefin in the hydrocarbon phase 1 was 72.1% by weight, the content of n-paraffin was 23.12% by weight, and the content of oxygen-containing compound was 75ppm (the alcohol content was 0ppm, the aldehyde and ketone contents were 52ppm, and the acid and ester contents were 23ppm) as determined by gas chromatography.
Comparative example 4
The process of example 1 was followed except that the aqueous methanol solution in step (2) was replaced with water. That is, 1000g of the first stage fraction was taken and subjected to multistage countercurrent extraction with water in a first extraction column to obtain 1000g of a hydrocarbon phase 1, the recovery rate of the hydrocarbon phase was 100%, and the content of α -olefin in the hydrocarbon phase 1 was 71.29% by weight, the content of n-paraffin was 22.02% by weight, the content of alcohol in the oxygen-containing compound was 2.60% by weight, the content of aldehyde and ketone was 0.62% by weight, and the content of acid and ester was 0.14% by weight, as measured by gas chromatography.
Comparative example 5
The procedure of example 1 was followed, except that the aqueous ethanol solutions in step (2) were each replaced with an aqueous methanol solution. That is to say that the first and second electrodes,
taking 1000g of the second-stage fraction, and carrying out multi-stage countercurrent extraction on the second-stage fraction by using a 69 wt% methanol aqueous solution in a second extraction tower to obtain 961.0g of a hydrocarbon phase 2, wherein the recovery rate of the hydrocarbon phase 2 is 99.2%, and the content of alpha-olefin, n-alkane and oxygen-containing compounds in the hydrocarbon phase 2 is 67.69 wt%, 22.83 wt% and 1.29 wt% (the content of alcohol is 1.01 wt%, the content of aldehyde and ketone is 0.22 wt%, and the content of acid and ester is 0.06 wt%) according to gas chromatography detection;
1000g of the third fraction were subjected to multistage countercurrent extraction with an aqueous methanol solution having a concentration of 80% by weight in a third extraction column to obtain 975.8g of a hydrocarbon phase 3, the recovery rate of the hydrocarbon phase 3 was 99.6%, and the content of α -olefin, the content of n-paraffin, and the content of oxygen-containing compound in the hydrocarbon phase 3 were 45.96% by weight, 46.03% by weight, and 1.94% by weight, respectively, as measured by gas chromatography (the content of alcohol was 1.65% by weight, the content of aldehyde and ketone was 0.22% by weight, and the content of acid and ester was 0.07% by weight).
It can be seen from the examples and comparative examples that the method of the present invention not only maintains the content of alpha-olefin during the process of removing the oxygen-containing compound, but also reduces the content of the oxygen-containing compound in the deoxidized and refined Fischer-Tropsch synthetic oil to below 100 ppm. The content of the oxygen-containing compound was high in the case of using only an aqueous ethanol solution (comparative example 1), an aqueous methanol solution (comparative example 2), a method according to the present invention in which the aqueous methanol solution in step (2) was replaced with water (comparative example 4), and a method according to the present invention in which the aqueous ethanol solution in step (2) was replaced with an aqueous methanol solution (comparative example 5). Furthermore, according to the process of the present invention but replacing the aqueous methanol solution in step (2) with an aqueous ethanol solution (comparative example 3), the oxygenate content in the deoxygenated refined Fischer-Tropsch synthesis oil could reach 100ppm or less, but the recovery of the hydrocarbon phase was only 90.0%, significantly lower than the process of the present invention.
In conclusion, the method not only maintains the content of the alpha-olefin in the process of removing the oxygen-containing compound, but also reduces the content of the oxygen-containing compound in the deoxidized and refined Fischer-Tropsch synthetic oil to be less than 100ppm and has high oil recovery rate.
The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.

Claims (10)

1. A method for removing oxygen-containing compounds from Fischer-Tropsch synthesis oil is characterized by comprising the following steps:
(1) carrying out atmospheric and vacuum fractionation on Fischer-Tropsch synthetic oil to obtain a first-stage fraction, a second-stage fraction and a third-stage fraction, wherein,
the distillation range of the first-stage fraction is IBP-TaThe temperature is less than or equal to 140 ℃ and T is less than or equal toa≤170℃；
The distillation range of the second-stage fraction is more than TaAnd is not more than TbThe temperature is less than or equal to 240 ℃ and T is less than or equal tob≤300℃；
The distillation range of the third-stage fraction is more than Tb℃；
(2) Carrying out first extraction on the first-stage fraction by using a methanol aqueous solution to obtain an extract phase 1 and a raffinate phase 1; performing second extraction on the second-stage fraction by using a first ethanol aqueous solution to obtain an extract phase 2 and a raffinate phase 2; performing third extraction on the third-stage fraction by using a second ethanol aqueous solution to obtain an extract phase 3 and a raffinate phase 3;
(3) washing the raffinate phase 1, the raffinate phase 2 and the raffinate phase 3 respectively to obtain deoxidized and refined Fischer-Tropsch synthetic oil;
the Fischer-Tropsch synthetic oil comprises 0.1-10 wt% of oxygen-containing compounds by total weight of the Fischer-Tropsch synthetic oil, wherein the oxygen-containing compounds comprise alcohols, ketones, aldehydes, acids and esters.
2. The process according to claim 1, wherein in step (1), the distillation range of the first stage fraction is IBP-TaFraction at 150 ℃ or lower, wherein T is not more than 150 ℃a≤160℃；
The distillation range of the second-stage fraction is more than TaAnd is not more than TbThe temperature is less than or equal to 260 ℃ and T is more than or equal tob≤280℃；
The distillation range of the third-stage fraction is more than Tb℃。
3. The process according to claim 1 or 2, wherein in step (2), the concentration of the aqueous methanol solution is not more than 85% by weight, preferably 60 to 75% by weight; the amount of the methanol aqueous solution is 0.5-4 times of the weight of the first-stage distillate, and preferably 0.8-2 times of the weight of the first-stage distillate.
4. The process according to claim 1 or 2, wherein in step (2), the concentration of the first aqueous ethanol solution is not more than 80% by weight, preferably 60-75% by weight; the dosage of the first ethanol water solution is 0.5-4 times of the weight of the second-stage distillate, and preferably 0.8-2 times.
5. The process according to claim 1 or 2, wherein in step (2), the concentration of the second aqueous solution of ethanol is not more than 90% by weight, preferably 75-85% by weight; the dosage of the second ethanol aqueous solution is 0.5-4 times of the weight of the third section fraction, and preferably 0.8-2 times.
6. The process according to claim 1 or 2, wherein the temperature of the first extraction is 15-50 ℃, preferably 20-50 ℃; the first extraction method is a multi-stage countercurrent extraction method; the theoretical stage number of the first extraction is 3-10 stages, and preferably 5-7 stages.
7. The process according to claim 1 or 2, wherein the temperature of the second extraction is 15-50 ℃, preferably 20-50 ℃; the second extraction method is a multi-stage countercurrent extraction method; the theoretical stage number of the second extraction is 3-10 stages, and preferably 5-7 stages.
8. The process according to claim 1 or 2, wherein the temperature of the third extraction is 15-50 ℃, preferably 20-50 ℃; the third extraction method is a multi-stage countercurrent extraction method; the theoretical stage number of the third extraction is 3-10 stages, and preferably 5-7 stages.
9. A process according to claim 1 or claim 2, wherein the fischer-tropsch synthesis oil has a boiling range of IBP to 380 ℃, preferably IBP to 350 ℃.
10. The process of claim 1 or 2, further comprising subjecting the extract phase 1, extract phase 2 and extract phase 3 to solvent separation to obtain oxygenates and recycled solvent.
CN201910214185.9A 2019-03-20 2019-03-20 Method for removing oxygen-containing compounds from Fischer-Tropsch synthetic oil Pending CN111718748A (en)

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