CN115975672A - Process for removing oxygenates from a hydrocarbon-containing stream - Google Patents
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Abstract
The invention relates to the field of removing oxygenated compounds from hydrocarbon-containing streams, and provides a method for removing oxygenated compounds from hydrocarbon-containing streams. The method comprises the following steps: 1) Contacting a hydrocarbon-containing material flow with a sodium borohydride material flow for reaction, mixing the obtained product with water, and then removing the water to obtain a water-removing phase; 2) Carrying out countercurrent extraction on the dewatering phase and an extraction solvent containing the composite extractant to obtain an extract phase and a raffinate phase; 3) Washing the raffinate phase with water to obtain a deoxygenated hydrocarbon phase; recovering the solvent from the mixture obtained at the same time, and/or returning and adding the solvent extracted in the step 2); 4) And (3) recovering the solvent from the extraction phase, circularly adding the obtained solvent into the extraction solvent obtained in the step 2), standing and layering the obtained aqueous organic matter, separating the bottom material obtained by layering, and circularly returning the water phase obtained by separation to the step 3). The content of alpha-olefin in the Fischer-Tropsch naphtha is kept, oxygen-containing compounds such as alcohol, ketone, aldehyde, acid, ester and the like are effectively removed, and the oil recovery rate is high.
Description
Technical Field
The invention relates to the field of removing oxygen-containing compounds from hydrocarbon-containing streams, in particular to a method for removing oxygen-containing compounds from hydrocarbon-containing streams.
Background
Oxygenates are present in the fischer-tropsch naphtha, the product obtained from the fischer-tropsch synthesis reaction. Oxygenates are mainly fatty alcohols, with small amounts of acids, esters, ketones, aldehydes, and the like. The existence of oxygen-containing compounds in Fischer-Tropsch naphtha can easily cause the poisoning and inactivation of catalysts in a downstream industrial chain, so that the cost and the operation cost of a subsequent product utilization process are increased, the comprehensive utilization of the Fischer-Tropsch naphtha product and the extension of the industrial chain are limited, and the content of carbonyl oxygen is strictly regulated in the application of oxygen-containing compounds and a plurality of subsequent olefins, so that the removal of the aldehyde ketone compounds is a very important problem.
Currently, the removal of oxygenates in industry mainly employs a method of hydrogenating compounds containing olefins, alkanes and oxygenates. However, hydrogenation also accompanies olefin hydrogenation saturation in the process of removing oxide by hydrogenation, which affects the application of subsequent olefin, especially alpha-olefin.
Other methods for separating and extracting fatty alcohol and removing oxygen-containing compounds also comprise adsorption, extraction and the like. In the conventional adsorption and extraction methods, the Fischer-Tropsch naphtha is firstly cut into a plurality of sections of fractions, and then different fractions are extracted or extracted and rectified, or other treatment means are combined to realize the removal of the oxygen-containing compounds.
However, in the prior art, the content of alpha-olefin is difficult to maintain by adopting a hydrodeoxygenation method; in the extraction method, low-boiling-point low-carbon alcohol is used as an extracting agent in some patents, and the whole extracting agent needs to be distilled out during recovery, so the recovery cost of the extracting agent is high, and the boiling points of methanol, ethanol and isopropanol are contained in the distillation range of Fischer-Tropsch oil and cannot be removed by rectification, thereby further causing the separation difficulty.
Therefore, how to better remove the oxygen-containing compounds in the fischer-tropsch naphtha, especially the aldehyde ketone compounds, better separate and recover the extracting agent, and better retain the hydrocarbon products, needs to improve the technical means for removing the oxygen-containing compounds from the fischer-tropsch naphtha.
Disclosure of Invention
The invention aims to solve the problems that aldehyde ketone compounds are difficult to remove and cannot meet the requirement of carbonyl oxygen content in subsequent alpha-olefin application when the oxygen-containing compounds are removed from full-fraction Fischer-Tropsch naphtha in the prior art, and provides a method and a system for removing the oxygen-containing compounds from hydrocarbon streams.
The inventor of the invention finds that the difficulty in removing aldehyde and ketone is high and the alcohol is relatively easy to remove in the process of extracting and deoxidizing the hydrocarbon-containing material flow in the research process. Further research has thus been carried out to address this problem.
In order to achieve the above object, a first aspect of the present invention provides a process for removing oxygenates from a hydrocarbon stream comprising:
(1) Contacting a hydrocarbon-containing material flow with a sodium borohydride material flow for reaction, mixing the obtained product with water, and then removing the water to obtain a water-removing phase;
(2) Carrying out countercurrent extraction on the dewatering phase and an extraction solvent containing a composite extractant to obtain an extract phase and a raffinate phase;
(3) Washing the raffinate phase with water to obtain a deoxygenated hydrocarbon phase; recovering the solvent from the mixture obtained at the same time, and/or returning and adding the extraction solvent in the step (2);
(4) And (3) recovering the solvent from the extract phase, circularly adding the obtained solvent into the extract solvent in the step (2), standing and layering the obtained aqueous organic matter, separating the bottom material obtained by layering, and circularly returning the water phase obtained by separation to the step (3).
Through the technical scheme, the method can realize removal of the oxygenates from the whole fraction of the Fischer-Tropsch naphtha by an extraction method, wherein aldehydes, ketones and even acid esters which are difficult to remove are all converted into alcohols which are relatively easier to remove by a reaction of adding sodium borohydride, so that the removal difficulty of the oxygenates is reduced, the oxygenates can be removed less, and the same deoxidation effect and extraction deoxidation severity can be reduced. The method of the invention not only can keep the content of alpha-olefin in Fischer-Tropsch naphtha, the retention rate of the alpha-olefin can reach more than 99 percent, but also can effectively remove oxygen-containing compounds such as alcohol, ketone, aldehyde, acid, ester and the like in the Fischer-Tropsch naphtha, the content of carbonyl oxygen in the deoxidized Fischer-Tropsch naphtha is reduced to be less than 5ppm (mass), and the recovery rate of oil products is high and reaches more than 92 percent.
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FIG. 1 is a schematic flow diagram of a method provided by the present invention.
Description of the reference numerals
1. Reaction 2, extraction 3, washing with water
4. Solvent recovery 5, standing and layering 6, separation
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.
The invention provides a method for removing oxygenated compounds from a hydrocarbon-containing stream, which comprises the following steps:
(1) Contacting a hydrocarbon-containing material flow with a sodium borohydride material flow for reaction, mixing the obtained product with water, and then removing the water to obtain a water-removing phase;
(2) Carrying out countercurrent extraction on the dehydrated phase and an extraction solvent containing a composite extractant to obtain an extract phase and a raffinate phase;
(3) Washing the raffinate phase with water to obtain a deoxygenated hydrocarbon phase; recovering the solvent from the mixture obtained at the same time, and/or returning and adding the extraction solvent in the step (2);
(4) And (3) recovering the solvent from the extract phase, circularly adding the obtained solvent into the extract solvent in the step (2), standing and layering the obtained aqueous organic matter, separating the bottom material obtained by layering, and circularly returning the water phase obtained by separation to the step (3).
In some embodiments of the invention, the hydrocarbon-containing stream comprises alkanes, alkenes, and oxygenates. The hydrocarbon-containing stream contains a large amount of organic compounds, and may contain alkanes, olefins and oxygen-containing compounds having a boiling point of not more than 200 ℃, by reflecting the carbon number of the contained organic compounds by the boiling point. Preferably, the hydrocarbon-containing stream has a distillation range of from 30 to 200 ℃; the hydrocarbon-containing stream may also have a distillation range of from 30 to 130 c, preferably from 40 to 120 c. More particularly, the hydrocarbon-containing stream which can be satisfied can be a naphtha fraction, typically preferably a condensation product of the fischer-tropsch synthesis reaction, which can be a condensation product of the low-temperature or high-temperature fischer-tropsch reaction. More preferably, the hydrocarbonaceous stream is Fischer-Tropsch naphtha having an alpha-olefin content of from 40 to 70wt%, preferably from 50 to 70wt%.
In some embodiments of the present invention, the oxygenate in the hydrocarbon-containing stream needs to be removed by the process provided by the present invention. Preferably, the oxygenate comprises at least one of an alcohol, a ketone, an aldehyde, a carboxylic acid, and an ester. Further, the total content of said oxygenates in said hydrocarbon-containing stream is from 0.1 to 10wt% based on the total amount of said hydrocarbon-containing stream. Further, the main oxygen-containing compound in the oxygen-containing compounds is alcohol, and the content of the alcohol is 0.04-9.9wt%; the total content of ketone and aldehyde can be determined as the carbonyl oxygen content and can be from 0.05 to 1% by weight, and the ester content can be from 0.01 to 0.2% by weight.
In some embodiments of the invention, the sodium borohydride stream comprises sodium borohydride and a solvent; preferably, the solvent is selected from at least one of water, methanol and ethanol.
In some embodiments of the present invention, preferably, the sodium borohydride stream is based on the molar amount of sodium borohydride, the hydrocarbon containing stream is based on the total molar amount of aldehydes and ketones contained, and the molar ratio of the sodium borohydride stream to the hydrocarbon containing stream is from 1 to 2:1.
further, in some embodiments of the present invention, the process of step (1) comprises: and (3) reacting the hydrocarbon-containing material flow and the sodium borohydride material flow for 30min-2h under stirring, adding water into a product obtained after the reaction is finished, continuously stirring for 10-30min, then standing for 15-60min for layering and removing a water phase.
In some embodiments of the invention, the removal of oxygenates by extraction of the hydrocarbon-containing stream can be achieved using the composite extractant. Preferably, the composite extracting agent is at least one selected from ester compounds, glycol compounds, amide compounds, pyrrolidone compounds, dihydric alcohol compounds and alcohol amine compounds; and/or the extraction solvent further comprises water. Wherein the ester compound is at least one of benzoate compound, carbonate compound and lactone compound; the ester compound is at least one of dimethyl phthalate, ethylene glycol carbonate and gamma-butyrolactone. The glycol compound is at least one of diethylene glycol and triethylene glycol. The amide compound is at least one selected from N, N-dimethylformamide and N, N-dimethylacetamide. The pyrrolidone compound can be N-methyl pyrrolidone. The dihydric alcohol compound can be at least one of ethylene glycol and propylene glycol. The alcohol amine compound can be ethanolamine.
In some embodiments of the present invention, preferably, the extraction solvent further comprises water. Preferably, the water content in the extraction solvent is not more than 50 wt.%, preferably 0-20 wt.%. When the extraction solvent contains water, the selectivity of the composite extraction agent can be obviously improved.
In some embodiments of the invention, in the conditions under which step (2) effects the extraction, preferably the weight ratio of the extraction solvent to the hydrocarbon-containing stream is from 0.5 to 4:1, preferably 0.8 to 2:1.
in some embodiments of the invention, it is preferred that the extraction temperature is from 10 to 50 ℃, preferably from 20 to 50 ℃. The operation process of the extraction can be a multi-stage countercurrent extraction method. Preferably, the theoretical number of stages of the multistage countercurrent extraction may be 5 to 12 stages, preferably 7 to 10 stages. The extraction can be carried out in an extraction column, with a raffinate phase at the top and an extract phase at the bottom. The extract phase is rich in oxygen-containing compounds; the raffinate phase is rich in hydrocarbon compounds and low in oxygen-containing compounds.
According to the method provided by the invention, the raffinate phase obtained in the step (2) contains a small amount of the extraction solvent, and the extraction solvent can be washed away by a water washing method in the step (3) to obtain a deoxygenated hydrocarbon phase, namely deoxygenated naphtha. The water washing can be carried out by introducing the raffinate phase into a water washing tower, the hydrocarbon phase is led out as a tower top product, a mixture of water and a small amount of extraction solvent can be obtained at the tower bottom, and the mixture can be directly returned to the step (2) for recycling and can also enter a recovery tower for solvent recovery treatment. Preferably, the conditions of the water washing include: the washing temperature is 10-80 ℃, and the weight ratio of water to raffinate phase is 0.2-1:1.
in some embodiments of the present invention, the solvent recovery of the extract phase may be performed by rectification, and the oxygenate and the recycle solvent may be obtained and may be performed in a recovery column. And (3) obtaining a circulating solvent at the bottom of the recovery tower, containing the composite extracting agent and being capable of returning to the step (2) for recycling. In the present invention, at least a part of the mixture obtained at the bottom of the water washing column may be returned to step (2) together with the recycled solvent obtained at the bottom of the recovery column, and the recycled solvent may be added to the extraction solvent for recycling, so that the water content in the recycled solvent obtained can be adjusted. In the invention, another part of the mixture obtained from the bottom of the water washing tower and the extraction phase can enter a recovery tower together for solvent recovery. The top of the recovery tower obtains a recovered material which can contain oxygen-containing compounds, water and a small amount of hydrocarbons. Further, the recovered material is still stratified after being drawn out, and can be introduced into a decantation tower to be carried out, so that a water-insoluble organic phase, mainly oxygen-containing compounds and a small amount of hydrocarbons, is obtained at the top of the decantation tower, and mainly water and water-soluble oxygen-containing compounds are obtained at the bottom of the decantation tower. Preferably, the solvent recovery conditions include: the temperature is 150-250 ℃, the pressure is-0.01 to-0.08 MPa, and the reflux ratio is 0.5-1. The reflux ratio is the weight ratio of the flow of reflux liquid returned into the recovery tower to the flow of materials recovered at the top of the recovery tower. The temperature may refer to the temperature of the bottom of the recovery column.
In some embodiments of the invention, the material obtained at the bottom of the decantation tower via a still standing separation can be further separated to separate an organic phase and water. Preferably, the separation is rectification or stripping. Specifically, the material obtained from the bottom of the decantation tower can be introduced into a rectification tower or a stripping tower, an organic phase containing oxygen compounds is mainly obtained at the top of the rectification tower or the stripping tower, and water is mainly obtained at the bottom of the rectification tower or the stripping tower; further, the obtained water was circulated to the water washing tower. In some embodiments of the present invention, preferably, the stripping conditions comprise: the temperature is 100-120 ℃, the pressure is normal pressure, and the reflux ratio is 1-2; the rectification conditions include: the temperature is 100-120 ℃, the pressure is normal pressure, and the reflux ratio is 1-2.
By the process provided by the present invention, the recovery of olefins and paraffins in the extracted product, deoxygenated naphtha, is preferably greater than 92% while at least substantially maintaining the olefin/paraffin ratio. Not only maintains the content of alpha-olefin in Fischer-Tropsch naphtha, but also can effectively remove alcohol, ketone, aldehyde, acid and ester in the Fischer-Tropsch naphtha, the content of carbonyl oxygen in the deoxidized Fischer-Tropsch naphtha is reduced to be less than 5ppm (mass), and the oil recovery rate is high.
In accordance with one embodiment of the present invention, a process for removing oxygenates from fischer-tropsch derived naphtha is provided. The process may be carried out in the following oxygenate removal system, the system comprising: the device comprises a stirring reaction kettle, an extraction tower, a water washing tower, a recovery tower, a decantation tower and a separation unit; wherein the middle-lower part of the bottom of the stirring reaction kettle is communicated with a lower feed inlet of the extraction tower; the top of the extraction tower is communicated with a washing tower, the bottom of the extraction tower is communicated with a recovery tower, a lower feed port is arranged on the extraction tower and used for feeding Fischer-Tropsch naphtha, and an upper feed port is arranged on the extraction tower and used for feeding an extraction solvent; the washing tower is provided with a lower feed inlet for raffinate phase feeding, an upper feed inlet for water feeding, a tower top outlet for discharging the obtained deoxidized naphtha product, and a bottom outlet for discharging tower bottom materials, and is communicated with the upper feed inlet of the extraction tower and the feed inlet of the recovery tower; the recovery tower is provided with a recovery feed inlet communicated with the bottom of the extraction tower and the bottom outlet of the water washing tower, a tower top recovery discharge outlet, and a bottom outlet of the recovery tower and communicated with the feed inlet at the upper part of the extraction tower; the decantation tower is provided with a decantation feed inlet communicated with the recovery discharge outlet, an organic phase outlet at the top of the tower and a discharge outlet at the bottom of the tower; the separation unit can be a rectifying tower or a stripping tower, the separation unit is provided with a separation feed inlet communicated with a discharge outlet at the bottom of the decanting tower, a discharge outlet at the top of the separation unit, a unit bottom outlet communicated with a feed inlet at the upper part of the water washing tower, and an organic phase outlet at the top of the separation unit. The method provided by the invention can be implemented in the system, and comprises the following steps as shown in figure 1:
adding a sodium borohydride material flow into the whole fraction of the Fischer-Tropsch naphtha, wherein the sodium borohydride material flow can contain at least one solvent of water, methanol and ethanol, adding water into a product after full reaction, then standing for layering, and removing a water phase to obtain a water-removed phase;
respectively introducing the water-removing phase and the extraction solvent containing the composite extractant provided by the invention through a lower feed inlet and an upper feed inlet of the extraction tower, and performing multi-stage countercurrent extraction to obtain an extract phase and a raffinate phase;
introducing the raffinate phase into a water washing tower, washing off a small amount of extraction solvent contained in the raffinate phase by a water washing method, and extracting deoxygenated naphtha serving as a product from the top of the water washing tower, wherein the deoxygenated naphtha contains more than 99wt% of olefins and alkanes, and the content of carbonyl oxygen is less than 5ppm (mass); the mixture of water and a small amount of extraction solvent obtained at the bottom of the water washing tower can be divided into a material A strand and a material B strand, wherein the material A strand returns to the extraction tower and is added with the extraction solvent, and the material B strand is mixed with the extraction phase and enters a recovery tower;
the B strand and the extract phase enter a recovery tower for rectification recovery, a recovered material containing an oxygen-containing compound, water and a small amount of olefin and alkane is obtained from the tower top of the recovery tower, a circulating solvent (which can mainly contain a composite extracting agent) is obtained from the tower bottom of the recovery tower, and the circulating solvent can be returned and added into the extracting solvent for recycling; in the invention, the amount and the composition of the material A strand and the circulating solvent returned when the material A strand and the circulating solvent are returned and added into the extraction solvent are used for adjusting the composition of the extraction solvent to meet the extraction process, for example, the material A strand and the circulating solvent can be mixed to prepare a proper composition to be added into the extraction solvent, if the water content of the material after the mixing preparation is excessive, the mixture can be distributed to more B strands, even the whole mixture obtained at the bottom of a water washing tower enters a recovery tower;
introducing the recovered material obtained from the top of the recovery tower into a decantation tower for standing separation, obtaining an organic phase at the top of the decantation tower from the upper part of the decantation tower, wherein the organic phase can contain oxygen-containing compounds and a small amount of hydrocarbons, and obtaining a bottom material at the bottom of the decantation tower, namely recovered water and a small amount of water-soluble oxygen-containing compounds; further, the bottom material of the decant tower is introduced into a separation unit, such as a rectification tower or a stripping tower, to separate water and oxygen-containing compounds, wherein the oxygen-containing compounds are obtained at the top of the tower, and the water is obtained at the bottom of the tower and is recycled back to the washing tower.
The present invention will be described in detail below by way of examples.
Recovery of the deoxygenated naphtha% = the mass of deoxygenated naphtha obtained from the top of the water washing column/(feed amount of Fischer-Tropsch naphtha × (1-content of oxygen-containing compound%)) × 100%
The content of each component in the Fischer-Tropsch naphtha is measured by a chromatographic method, wherein the content of alcohol and ester in the oxygen-containing compound is measured by a chromatographic method, and the content of carbonyl oxygen is measured by referring to GB/T6324.5-2008;
the composition and content of Fischer-Tropsch naphtha 1 are shown in Table 1, and the distillation range is 33-200 ℃.
The composition and content of Fischer-Tropsch naphtha 2 are shown in Table 1, with a boiling range of 33-130 ℃.
TABLE 1
Example 1
(1) The raw material is Fischer-Tropsch naphtha 1, 20kg of the raw material is added into a stirring reaction kettle, 324g of sodium borohydride is dissolved in 300g of methanol and stirred for 1h, 1000g of water is added after the reaction is finished and stirred for 20min, the mixture is kept stand for 30min, and the water phase is discharged.
(2) Using diethylene glycol as a composite extraction solvent, performing multi-stage countercurrent extraction with the reacted hydrocarbon phase in an extraction tower, wherein the extraction temperature is 20 ℃, the feeding speed of the composite extraction solvent is 15g/min, the feeding speed of the hydrocarbon phase is 10g/min (the weight ratio of the composite extraction solvent to the raffinate hydrocarbon phase is 1.5).
(3) Introducing the raffinate phase into a washing tower, washing off a small amount of diglycol by a washing method, wherein the washing temperature is 50 ℃, and the weight ratio of water to the raffinate phase is 0.3:1, obtaining a deoxygenated naphtha product; and (4) water washing liquid (containing diglycol and water) obtained from the bottom of the water washing tower is totally used as water washing liquid B to enter the recovery tower.
(4) And (3) feeding the raffinate phase and the water washing liquid B strand into a recovery tower for solvent recovery, wherein the conditions comprise that: 190-195 deg.C, pressure-0.05 MPa, reflux ratio of 0.5 to obtain bottom product (mainly containing diethylene glycol), and top product containing water.
(5) Introducing the water-containing organic matter into a decantation tower for standing separation, and discharging an organic phase obtained at the top of the tower; introducing the lower layer material obtained at the bottom of the tower and a mixture (mainly containing water and oxide) mixed with the extraction water into a rectifying tower to separate water and the oxide, wherein the conditions comprise that: the temperature is 110-115 ℃, the pressure is normal pressure, and the reflux ratio is 2. And recycling the obtained water to a water washing tower for recycling.
100min was taken for material balance to obtain 918.7g of deoxygenated naphtha, with recovery of 95.0%.
The content of α -olefin in the deoxygenated naphtha was 52.5wt% (α -olefin retention 99.5%), the content of alcohol in the oxygen-containing compound was 0ppm by weight, and the content of carbonyl oxygen was 3ppm by weight, as measured by gas chromatography.
Example 2
(1) The raw material is Fischer-Tropsch naphtha 2, 20kg of the raw material is added into a stirring reaction kettle, 243g of sodium borohydride is dissolved in 300g of methanol and stirred for 1h, 1000g of water is added after the reaction is finished and stirred for 20min, the mixture is kept stand for 30min, and the water phase is discharged.
(2) The extraction solvent contains 15wt% of water, and the compound extractant is gamma-butyrolactone. And (2) carrying out multi-stage countercurrent extraction on the reacted hydrocarbon phase and an extraction solvent (containing gamma-butyrolactone and 15wt% of water) in an extraction tower, wherein the extraction temperature is 25 ℃, the feeding speed of the raw material is 10g/min, the feeding speed of the extraction solvent is 12g/min (the weight ratio of the extraction solvent to the raw material is 1.2.
(3) Introducing raffinate phase at the top of the extraction tower into a water washing tower, washing off the extraction solvent by a water washing method, wherein the water washing temperature is 30 ℃, and the weight ratio of water to raffinate phase is 0.4:1, obtaining a deoxygenated naphtha product; the mixture (gamma-butyrolactone and water) obtained at the bottom of the water washing tower is divided into two parts (A strand and B strand), and the A strand can be directly returned to the extraction tower for recycling; and introducing the B strand and the extract phase into a recovery tower for solvent recovery through rectification recovery.
(4) And B strand and the extraction phase are introduced into a recovery tower to carry out solvent recovery through rectification recovery, wherein the rectification recovery conditions are as follows: the temperature is 190-195 ℃, the pressure is-0.05 MPa, and the reflux ratio is 0.5;
wherein, the water washing liquid A strand and the bottom product of the solvent recovery tower are converged to obtain the circulating extraction solvent, the dosage of the water washing liquid A strand ensures that the water content in the circulating extraction solvent is 10wt%, and the balance of the water washing liquid is the water washing liquid B strand.
(5) Introducing the recovered material obtained from the top of the recovery tower into a decantation tower for standing separation, introducing the tower bottom material obtained from the bottom of the recovery tower into a rectification tower for separating water and oxygen-containing compounds, wherein the conditions comprise: the temperature is 105-110 ℃, the pressure is normal pressure, and the reflux ratio is 1. And recycling the obtained water to a water washing tower.
100min was taken for material balance to obtain 917.9g of deoxygenated naphtha, with recovery of 95.0%.
The content of α -olefin in the deoxygenated naphtha was 51.3wt% (α -olefin retention 99.8%), the content of alcohol in the oxygen-containing compound was 0ppm by weight, and the content of carbonyl oxygen was 2ppm by weight, as measured by gas chromatography.
Example 3
(1) The raw material is Fischer-Tropsch naphtha 2, 20kg of the raw material is added into a stirring reaction kettle, 243g of sodium borohydride is dissolved in 300g of water and stirred for 1.5h, 1000g of water is added after the reaction is finished and stirred for 20min, the mixture is kept stand for 30min, and the water phase is discharged.
(2) The extraction solvent contains 10wt% of water, the contained composite extracting agent is N, N-dimethylacetamide, multistage countercurrent extraction is carried out on the reacted hydrocarbon phase in the extraction tower, the second extraction temperature is 30 ℃, the feeding speed of the composite extraction solvent is 10g/min, the feeding speed of the hydrocarbon phase is 10g/min (the weight ratio of the composite extraction solvent to the raffinate hydrocarbon phase is 1:1), and the extraction theoretical stage number is 7, so that the extraction phase and the raffinate phase are obtained.
(3) Introducing the raffinate phase into a water washing tower, washing a small amount of N by using a water washing method, wherein the water washing temperature of N-dimethylacetamide is 40 ℃, and the weight ratio of water to the raffinate phase is 0.5:1, obtaining a deoxidized naphtha product; the water washing liquid (containing N, N-dimethylacetamide and water) obtained from the bottom of the water washing tower is divided into a water washing liquid A strand and a water washing liquid B strand.
(4) The conditions for solvent recovery by feeding the raffinate phase and the water washing liquid B strand into a recovery tower comprise that: 160-165 ℃, the pressure is-0.08 MPa, the reflux ratio is 0.5, a second bottom product (mainly containing N, N dimethyl acetamide) is obtained, and a hydrous organic matter is obtained at the top of the tower.
Wherein, the water washing liquid A strand and the bottom product of the solvent recovery tower are converged to obtain the circulating extraction solvent, the dosage of the water washing liquid A strand ensures that the water content in the circulating extraction solvent is 15wt%, and the balance of the water washing liquid is the water washing liquid B strand.
(5) Introducing the water-containing organic matter into a decantation tower for standing separation, and discharging an organic phase obtained at the top of the tower; the lower layer material obtained at the bottom of the tower and the mixture (mainly containing water and oxide) mixed with the extraction water are introduced into a stripping tower to separate water and the oxide, and the conditions comprise that: the temperature is 100-115 ℃, the pressure is normal pressure, and the reflux ratio is 2. And recycling the obtained water to a water washing tower for cyclic utilization.
100min is taken for material balance to obtain 898.6g of deoxidized naphtha, and the recovery rate of the deoxidized naphtha is 93 percent.
The content of alpha-olefin in the deoxygenated naphtha was 50.9wt% (alpha-olefin retention 99.0%), the content of alcohol in the oxygen-containing compound was 0ppm by weight, and the content of carbonyl oxygen was 4ppm by weight, as measured by gas chromatography.
Example 4
(1) The raw material is Fischer-Tropsch naphtha 1, 20kg of the raw material is added into a stirring reaction kettle, 259.4g of sodium borohydride is dissolved in 300g of methanol and stirred for 2 hours, 1000g of water is added after the reaction is finished and stirred for 30min, the mixture is kept stand for 30min, and the water phase is discharged.
(2) The extraction solvent contains 20wt% of water, the compound extraction agent is N-methyl pyrrolidone, multistage countercurrent extraction is carried out on the extraction solvent and the reacted hydrocarbon phase in an extraction tower, the extraction temperature is 40 ℃, the feeding speed of the compound extraction solvent is 10g/min, the feeding speed of the hydrocarbon phase is 10g/min (the weight ratio of the compound extraction solvent to the hydrocarbon phase is 1:1), the extraction theoretical stage is 10 stages, and the extraction phase and the raffinate phase are obtained.
(3) Introducing the raffinate phase into a water washing tower, washing off a small amount of N-methyl pyrrolidone by a water washing method, wherein the water washing temperature is 35 ℃, and the weight ratio of water to the raffinate phase is 0.4:1, obtaining a deoxygenated naphtha product; the water washing liquid (containing N-methyl pyrrolidone and water) obtained from the bottom of the water washing tower is divided into a water washing liquid A strand and a water washing liquid B strand.
(4) And (3) enabling raffinate phase and water washing liquid B to enter a recovery tower for solvent recovery, wherein the conditions comprise that: 195-200 deg.c, pressure of-0.08 MPa and reflux ratio of 0.5. To obtain a bottom product (mainly containing N-methyl pyrrolidone), and obtain a hydrous organic matter at the top of the tower.
Wherein, the water washing liquid A strand and the tower bottom product are converged to obtain the circulating extraction solvent, the dosage of the water washing liquid A strand ensures that the water content in the circulating extraction solvent is 20wt%, and the balance of the water washing liquid is the water washing liquid B strand.
(5) Introducing the water-containing organic matter into a decantation tower for standing separation, and discharging an organic phase obtained at the top of the tower; the lower layer obtained at the bottom of the tower is introduced into a stripping tower together with a mixture (mainly containing water and oxide) of the extraction water to separate water and the oxide, and the conditions comprise that: the temperature is 115-120 ℃, the pressure is normal pressure, and the reflux ratio is 2. And recycling the obtained water to a water washing tower for cyclic utilization.
100min is taken for material balance to obtain 909.0g of deoxygenated naphtha, and the recovery rate of the deoxygenated naphtha is 94%.
The content of alpha-olefin in the deoxygenated naphtha was 50.9wt% (alpha-olefin retention 99.1%) and the content of carbonyl oxygen was 3ppm by weight, as determined by gas chromatography.
Comparative example 1
(1) The raw material is Fischer-Tropsch naphtha 1, the extraction solvent contains 20wt% of water, the contained composite extraction agent is N-methyl pyrrolidone, multistage countercurrent extraction is carried out on the raw material and a hydrocarbon phase in an extraction tower, the extraction temperature is 40 ℃, the feeding speed of the composite extraction solvent is 10g/min, the feeding speed of the hydrocarbon phase is 10g/min (the weight ratio of the composite extraction solvent to the hydrocarbon phase is 1:1), the extraction theoretical stage number is 10, and an extraction phase and a raffinate phase are obtained.
(3) Introducing the raffinate phase into a water washing tower, washing off a small amount of N-methyl pyrrolidone by a water washing method, wherein the water washing temperature is 35 ℃, and the weight ratio of water to the raffinate phase is 0.4:1, obtaining a deoxidized naphtha product; the water washing liquid (containing N-methyl pyrrolidone and water) obtained from the bottom of the water washing tower is divided into a water washing liquid A strand and a water washing liquid B strand.
(4) And (3) enabling raffinate phase and water washing liquid B to enter a recovery tower for solvent recovery, wherein the conditions comprise that: 195-200 deg.C, pressure of-0.08 MPa, and reflux ratio of 0.5. To obtain a bottom product (mainly containing N-methyl pyrrolidone), and obtain a hydrous organic matter at the top of the tower.
Wherein the water washing solution A strand and the tower bottom product are converged to obtain the circulating extraction solvent, the dosage of the water washing solution A strand ensures that the water content in the circulating extraction solvent is 20wt%, and the balance of the water washing solution is the water washing solution B strand.
(5) Introducing the water-containing organic matter into a decantation tower for standing separation, and discharging an organic phase obtained at the top of the tower; the lower layer obtained at the bottom of the tower is introduced into a stripping tower together with a mixture (mainly containing water and oxide) of the extraction water to separate water and the oxide, and the conditions comprise that: the temperature is 115-120 ℃, the pressure is normal pressure, and the reflux ratio is 2. And recycling the obtained water to a water washing tower for cyclic utilization.
The material balance is carried out for 100min to obtain 909.0g of deoxidized naphtha, and the recovery rate of the deoxidized naphtha is 94 percent.
The content of alpha-olefin in the deoxygenated naphtha was 50.9wt% (alpha-olefin retention 99.1%) and the content of carbonyl oxygen was 12ppm by weight as determined by gas chromatography.
In conclusion, the method of the invention can not only reduce the carbonyl oxygen content in the deoxidized naphtha to below 5ppm, but also maintain the alpha-olefin content in the process of removing the oxygen-containing compounds.
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 process for removing oxygenates from a hydrocarbon-containing stream comprising:
(1) Contacting a hydrocarbon-containing material flow with a sodium borohydride material flow for reaction, mixing the obtained product with water, and then removing the water to obtain a water-removing phase;
(2) Carrying out countercurrent extraction on the dehydrated phase and an extraction solvent containing a composite extractant to obtain an extract phase and a raffinate phase;
(3) Washing the raffinate phase with water to obtain a deoxygenated hydrocarbon phase; recovering the solvent from the mixture obtained at the same time, and/or returning and adding the extraction solvent in the step (2);
(4) And (3) recovering the solvent from the extract phase, circularly adding the obtained solvent into the extract solvent in the step (2), standing and layering the obtained aqueous organic matter, separating the bottom material obtained by layering, and circularly returning the water phase obtained by separation to the step (3).
2. The method of claim 1, wherein the hydrocarbon-containing stream comprises alkanes, alkenes, and oxygenates;
and/or the hydrocarbon-containing stream has a distillation range of from 30 to 200 ℃;
and/or the hydrocarbon-containing stream is a naphtha fraction, preferably a Fischer-Tropsch synthesis reaction condensate.
3. The process according to claim 1 or 2, wherein the content of said oxygenates in the hydrocarbon-containing stream is from 0.1 to 10 wt. -%, based on the total amount of the hydrocarbon-containing stream;
preferably, the oxygenate comprises at least one of an alcohol, a ketone, an aldehyde, a carboxylic acid, and an ester.
4. A process according to any one of claims 1 to 3, wherein the sodium borohydride stream comprises sodium borohydride and a solvent;
preferably, the solvent is selected from at least one of water, methanol and ethanol;
preferably, the sodium borohydride stream is based on the molar amount of sodium borohydride, the hydrocarbon-containing stream is based on the total molar amount of aldehydes and ketones contained, and the molar ratio of the sodium borohydride stream to the hydrocarbon-containing stream is from 1 to 2:1.
5. the method of any one of claims 1-4, wherein the process of step (1) comprises: and (3) reacting the hydrocarbon-containing material flow and the sodium borohydride material flow for 30min-2h under stirring, adding water into a product obtained after the reaction is finished, continuously stirring for 10-30min, then standing for 15-60min for layering and removing a water phase.
6. The method according to any one of claims 1 to 5, wherein the composite extracting agent is at least one selected from ester compounds, glycol compounds, amide compounds, pyrrolidone compounds, glycol compounds and alcohol amine compounds;
and/or the extraction solvent further comprises water.
7. The method according to claim 6, wherein the ester compound is selected from at least one of benzoate compounds, carbonate compounds, and lactone compounds;
preferably, the ester compound is at least one selected from dimethyl phthalate, ethylene glycol carbonate and gamma-butyrolactone;
preferably, the glycol compound is at least one selected from diethylene glycol and triethylene glycol;
preferably, the amide compound is selected from at least one of N, N-dimethylformamide and N, N-dimethylacetamide;
preferably, the pyrrolidone compound can be N-methyl pyrrolidone;
preferably, the glycol compound may be at least one of ethylene glycol and propylene glycol;
preferably, the alcohol amine compound may be ethanolamine.
8. A process according to claim 6 or 7, wherein the extraction solvent has a water content of not more than 50wt%, preferably 0-20wt%.
9. The method of any one of claims 1-8, wherein the weight ratio of the extraction solvent to the hydrocarbon-containing stream is from 0.5 to 4:1, preferably 0.8 to 2:1;
preferably, the extraction temperature is from 10 to 50 deg.C, preferably from 20 to 50 deg.C.
10. The method of any one of claims 1-9, wherein the conditions for solvent recovery comprise: the temperature is 150-250 ℃, the pressure is-0.01 to-0.08 MPa, and the reflux ratio is 0.5-1;
and/or, the separation is rectification or stripping;
and/or, the stripping conditions include: the temperature is 100-120 ℃, the pressure is normal pressure, and the reflux ratio is 1-2; the rectification conditions comprise: the temperature is 100-120 ℃, the pressure is normal pressure, and the reflux ratio is 1-2.
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| GB934666A (en) * | 1960-12-08 | 1963-08-21 | Gen Aniline & Film Corp | Removal of aldehydes from ethylene oxide |
| US4686317A (en) * | 1985-12-31 | 1987-08-11 | Mobil Oil Corporation | Process for removing oxygenated compounds or other impurities from hydrocarbon streams |
| CN103638938A (en) * | 2013-12-31 | 2014-03-19 | 湘潭大学 | Preparation method of catalyst for biological oil hydrodeoxygenation |
| CN110818531A (en) * | 2019-11-12 | 2020-02-21 | 上海兖矿能源科技研发有限公司 | Method for treating oxygen-containing organic matters in Fischer-Tropsch synthesis reaction water |
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| GB934666A (en) * | 1960-12-08 | 1963-08-21 | Gen Aniline & Film Corp | Removal of aldehydes from ethylene oxide |
| US4686317A (en) * | 1985-12-31 | 1987-08-11 | Mobil Oil Corporation | Process for removing oxygenated compounds or other impurities from hydrocarbon streams |
| CN103638938A (en) * | 2013-12-31 | 2014-03-19 | 湘潭大学 | Preparation method of catalyst for biological oil hydrodeoxygenation |
| CN110818531A (en) * | 2019-11-12 | 2020-02-21 | 上海兖矿能源科技研发有限公司 | Method for treating oxygen-containing organic matters in Fischer-Tropsch synthesis reaction water |
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