CN114853573B - Separation and purification method and system for 1, 4-butanediol - Google Patents
Separation and purification method and system for 1, 4-butanediol Download PDFInfo
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Abstract
The invention provides a separation and purification method and a separation and purification system for 1, 4-butanediol, wherein an extractant in the method is a compound extractant, and the compatibility of a solvent after compounding and 1, 4-butanediol is better through the synergistic effect between a plurality of compounds, so that the separation efficiency in the extraction and rectification process is ensured, the relative volatility of 1, 4-butanediol and 2- (4-hydroxybutoxy) tetrahydrofuran is obviously increased, the high-precision separation of 1, 4-butanediol and 2- (4-hydroxybutoxy) tetrahydrofuran is realized through the extraction and rectification, and the high-purity 1, 4-butanediol with the purity of more than 99.99% is obtained. In addition, the ratio of the two products can be flexibly regulated according to the needs, the recovery rate of the 1, 4-butanediol is obviously improved, the loss rate of the 1, 4-butanediol is reduced to the maximum extent, and the economic benefit is improved. The invention has the advantages of simple system equipment, low investment, high separation efficiency and high product purity.
Description
Technical Field
The invention relates to the technical field of 1, 4-butanediol production, in particular to a separation and purification method and system of 1, 4-butanediol.
Background
1, 4-butanediol is an important basic organic chemical raw material for producing tetrahydrofuran, dibutyl terephthalate, gamma-butyrolactone, polyurethane and the like. In recent years, with the rapid development of degradable materials, the capacity of the degradable materials such as PBS (English full name: poly (butylene succinate); chinese full name: polybutylene succinate), PBAT (English full name: poly (butyleneadipamate-co-terephthalate)), and the like by taking 1, 4-butanediol as a raw material is increased, so that the demand of the upstream raw material 1, 4-butanediol is rapidly increased, and all large 1, 4-butanediol manufacturers in the world are expanded in energy and increase in yield.
At present, the synthetic routes of the 1, 4-butanediol are about tens, wherein one of the synthetic routes is to take maleic anhydride or succinic acid as a raw material, esterify and hydrogenate the maleic anhydride or succinic acid by using low-carbon alcohol to obtain the 1, 4-butanediol and recycle the low-carbon alcohol. In the method, the 1, 4-butanediol is subjected to side reaction, namely, the dehydrogenation is carried out to generate the hydroxybutanal, and the hydroxybutanal is continuously reacted with the 1, 4-butanediol to generate the cyclic acetal substance, namely, the 2- (4-hydroxybutoxy) tetrahydrofuran. Especially in the latter stages of the hydrogenation catalyst operation, the yield of 2- (4-hydroxybutoxy) tetrahydrofuran is significantly increased.
Although the amount of 2- (4-hydroxybutoxy) tetrahydrofuran produced during the hydrogenation reaction is small and the normal boiling point of the material reaches 246 ℃ and the difference between the boiling point of the material and that of 1, 4-butanediol is about 20 ℃, the minimum constant boiling point of the minimum constant boiling point is very close to that of 1, 4-butanediol because the 2- (4-hydroxybutoxy) tetrahydrofuran and the 1, 4-butanediol product form the minimum constant boiling point, and the byproduct cannot be removed by conventional rectification separation. In addition, 2- (4-hydroxybutoxy) tetrahydrofuran is a chromogenic substance, and very small amounts can adversely affect downstream applications starting from 1, 4-butanediol.
In recent years, in the process of synthesizing PBS and PBAT by taking 1, 4-butanediol as raw materials, the existence of 2- (4-hydroxybutoxy) tetrahydrofuran has obvious influence on the quality of products, so that the purity of the 1, 4-butanediol products is higher and higher. In the current industrial production process, the purity of the 1, 4-butanediol product is guaranteed to meet the downstream requirement only by losing the yield of the 1, 4-butanediol and improving the rectification operation condition, so that the waste of the 1, 4-butanediol product is caused, the productivity is reduced, and the method is quite unreasonable from the aspect of economy.
To address the effect of 2- (4-hydroxybutoxy) tetrahydrofuran on the purity of 1, 4-butanediol products, various documents have been reported, such as patent application numbers US4383895, JP61/197534, CN1216973, CN103044197B, CN103044198B, etc., which either limit the production of 2- (4-hydroxybutoxy) tetrahydrofuran or employ unconventional rectification, or the crude 1, 4-butanediol stream is reduced in 2- (4-hydroxybutoxy) tetrahydrofuran content by continuing the reaction. However, 1, 4-butanediol products having a purity of 99.9% or more cannot be obtained. In addition, a hydrogenation process is also needed in the production process, and the problems of complex process flow, harsh operation conditions, large investment and energy consumption, poor economy and the like exist.
Disclosure of Invention
The invention provides a separation and purification method and a separation and purification system for 1, 4-butanediol, which aim to solve the problem of lower purity in the existing 1, 4-butanediol production process.
The invention provides a separation and purification method of 1, 4-butanediol, which comprises the following steps:
s01: the crude 1, 4-butanediol is separated in a de-heavies column, and a mixture a containing 1, 4-butanediol and 2- (4-hydroxybutoxy) tetrahydrofuran is taken off from the side stream.
Crude 1, 4-butanediol is separated in a de-heavies column. In the invention, the crude 1, 4-butanediol is a product containing 1, 4-butanediol after maleic anhydride is esterified, hydrogenated and light components are removed. Wherein the content of 1, 4-butanediol is 85-90% of the total content of the product. The top of the heavy-removal tower is used for extracting light components such as gamma-butyrolactone, unreacted dimethyl succinate and the like; a mixture a containing 1, 4-butanediol and 2- (4-hydroxybutoxy) tetrahydrofuran is extracted from the side stream; 2- (4-hydroxy-butoxy) tetrahydrofuran and other heavy components are extracted from the bottom of the column.
In the process of separating crude 1, 4-butanediol in a heavy-removal tower, the heavy-removal tower adopts a packing tower, the packing height is 10-50 theoretical plates, the operating pressure is 5-25kPa, the reflux ratio is 5-10, the tower top temperature is 160-200 ℃, the tower bottom temperature is 180-220 ℃, and the concentration of 1, 4-butanediol in the tower bottom heavy component is lower than 20wt%.
S02: the mixture a enters a stripping tower for separation, 1, 4-butanediol is extracted from a side line, and 1, 4-butanediol rich in 2- (4-hydroxybutoxy) tetrahydrofuran is extracted from the bottom of the stripping tower.
The mixture a extracted from the side line of the heavy-removal tower directly enters a stripping tower for separation. Wherein, the tower top is used for extracting 1, 4-butanediol containing light components such as gamma-butyrolactone, the lateral line is used for extracting high-purity 1, 4-butanediol, and the tower bottom is used for extracting 1, 4-butanediol tower bottom product containing 2- (4-hydroxy butoxy) tetrahydrofuran. And (3) re-feeding the 1, 4-butanediol containing light components such as gamma-butyrolactone and the like extracted from the tower top into a heavy-removal tower for separation. The purity of the 1, 4-butanediol at the side stream is more than 99.9%. The concentration of 2- (4-hydroxy butoxy) tetrahydrofuran in the 1, 4-butanediol bottom product is 0.5-5 wt%.
In the process of separating the mixture a in the stripping tower, the stripping tower adopts a packing tower, the packing height is 20-50 theoretical plates, the operating pressure is 5-30kPa, the reflux ratio is 5-10, the tower top temperature is 140-180 ℃, the tower bottom temperature is 180-200 ℃, and the purity of the 1, 4-butanediol extracted from the side line is more than 99.9wt%.
S03: the bottom product of the stripping tower enters an extraction rectifying tower for separation, 1, 4-butanediol is extracted from the top of the stripping tower, and a mixture b containing 1, 4-butanediol, 2- (4-hydroxybutoxy) tetrahydrofuran and an extracting agent is extracted from the bottom of the stripping tower.
And (3) feeding the 1, 4-butanediol bottom product extracted from the bottom of the stripping tower into an extraction rectifying tower for separation. Wherein, ultra-high-purity 1, 4-butanediol is extracted from the tower top, and the purity of the 1, 4-butanediol is more than 99.99 percent; a mixture b containing 1, 4-butanediol, 2- (4-hydroxybutoxy) tetrahydrofuran and extractant is taken off at the bottom.
In the process of separating the 1, 4-butanediol bottom product in the extractive distillation tower, the extractive distillation tower adopts a packing tower, the packing height is 30-60 theoretical plates, the operating pressure is 1-10kPa, the reflux ratio is 5-10, the solvent ratio is 3-10, the temperature of the extractant entering the tower is 50-100 ℃, the temperature of the tower top is 120-180 ℃, the temperature of the tower bottom is 180-220 ℃, and the purity of the 1, 4-butanediol produced at the tower top is more than 99.99wt%.
In the invention, the extractant adopted by the extraction rectifying tower is a high-boiling point compound extractant, which comprises a high-boiling point aromatic ester compound, a nitro-containing aromatic ether compound and a furan compound containing benzene ring substituent. The furan compound containing benzene ring substituent can obviously increase the relative volatility of 1, 4-butanediol and 2- (4-hydroxy butoxy) tetrahydrofuran; the aromatic ester compound with high boiling point has higher boiling point, has good solubility to furan compounds with benzene ring substituent, and can increase the relative volatility of 1, 4-butanediol and 2- (4-hydroxy butoxy) tetrahydrofuran; the aromatic ether compound containing nitro can have good solubility to alcohol and ester compounds at the same time. Therefore, through the compounding of various compounds and the synergistic effect of components, the compatibility of the compounded solvent and the 1, 4-butanediol is better, so that the separation efficiency in the extraction and rectification process can be ensured, the relative volatility of the 1, 4-butanediol and the 2- (4-hydroxybutoxy) tetrahydrofuran is obviously increased, the high-precision separation of the 1, 4-butanediol and the 2- (4-hydroxybutoxy) tetrahydrofuran can be realized efficiently and economically through an extraction and rectification technology, and the high-purity 1, 4-butanediol with the purity of more than 99.99 percent is obtained.
In addition, the boiling point of the composite extractant is obviously higher than that of 2- (4-hydroxy butoxy) tetrahydrofuran, so that the extractant can be regenerated only by simple negative pressure distillation, and the extractant has wide source, low cost, stable performance, no pollution and can be recycled.
Specifically, the high boiling aromatic ester compound accounts for 10-60 wt%, the aromatic ether compound containing nitro accounts for 10-40 wt%, and the furan compound containing benzene ring substituent accounts for 10-60 wt%. More preferably, the aromatic ester compound accounts for 20 to 50 weight percent, the aromatic ether compound containing nitro accounts for 20 to 30 weight percent, and the furan compound containing benzene ring substituent accounts for 20 to 40 weight percent.
More specifically, the high boiling aromatic ester compound comprises one or more of dimethyl phthalate, diethyl phthalate and dioctyl phthalate. The aromatic ether compound containing nitro group comprises o-nitroanisole and/or o-nitrophenethyl ether. Furans containing benzene ring substituents include 2- (3-phenylpropyl) tetrahydrofuran and/or 2- (4-methoxyphenyl) tetrahydrofuran.
S04: separating the mixture b in a solvent regeneration tower, and collecting a mixture c of 1, 4-butanediol and 2- (4-hydroxybutoxy) tetrahydrofuran at the top of the solvent regeneration tower; and (5) extracting the regenerated extractant from the bottom of the tower.
And (3) the mixture b extracted from the bottom of the separation tower of the extraction rectifying tower enters a solvent regeneration tower for separation. Wherein, the mixture c of 1, 4-butanediol and 2- (4-hydroxy butoxy) tetrahydrofuran is taken out from the top of the tower, and the regenerated extractant is taken out from the bottom of the tower.
In the process of separating the mixture b in a solvent regeneration tower, the solvent regeneration tower adopts a packing tower, the packing height is 20-50 theoretical plates, the operating pressure is 1-10kPa, the reflux ratio is 1-10, the tower top temperature is 120-180 ℃, the tower bottom temperature is 200-240 ℃, the concentration of 2- (4-hydroxy butoxy) tetrahydrofuran in the mixture c is more than 10wt%, and the purity of the regenerated extractant is more than 99.9wt%.
S05: and the mixture c enters the de-weight tower for separation, and the regenerated extractant enters the extractive distillation tower.
The mixture c extracted from the top of the solvent regeneration tower directly returns to the middle lower part of the de-weight tower for separation; the regenerated extractant extracted from the bottom of the tower enters the upper part of the extractive distillation tower to participate in extractive distillation after being cooled.
The invention also provides a separation and purification system of the 1, 4-butanediol, which comprises a de-weighting tower, a stripping tower, an extraction rectifying tower and a solvent regeneration tower, wherein a side line of the de-weighting tower is connected with the stripping tower, the bottom of the stripping tower is connected with the extraction rectifying tower, the bottom of the extraction rectifying tower is connected with the solvent regeneration tower, and the top and the bottom of the solvent regeneration tower are respectively connected with the de-weighting tower and the extraction rectifying tower.
The technical scheme provided by the embodiment of the invention can comprise the following beneficial effects:
the invention provides a separation and purification method and a separation and purification system for 1, 4-butanediol, wherein an extractant in the method is a high-boiling point composite extractant, and the compatibility of a plurality of compounds and components is good, so that the compatibility of a compounded solvent and 1, 4-butanediol is good, the separation efficiency in the extraction and rectification process can be ensured, the relative volatility of 1, 4-butanediol and 2- (4-hydroxybutoxy) tetrahydrofuran is obviously increased, and the high-precision separation of 1, 4-butanediol and 2- (4-hydroxybutoxy) tetrahydrofuran can be realized efficiently and economically by an extraction and rectification technology, and the high-purity 1, 4-butanediol with the purity of more than 99.99% is obtained. In addition, through reasonable process flow, not only can the high-purity and ultra-high-purity 1, 4-butanediol be obtained simultaneously, but also the proportion of the two products can be flexibly regulated according to the needs, the recovery rate of the 1, 4-butanediol is remarkably improved, the loss rate of the 1, 4-butanediol is reduced to the maximum extent, and the economic benefit is improved. The invention has the advantages of simple system equipment, low investment, high separation efficiency, high product purity, flexible and adjustable product purity and high recovery rate of 1, 4-butanediol.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed.
Drawings
In order to more clearly illustrate the technical solution of the present invention, the drawings that are needed in the embodiments will be briefly described below, and it will be obvious to those skilled in the art that other drawings can be obtained from these drawings without inventive effort.
FIG. 1 is a schematic diagram of a separation and purification system for 1, 4-butanediol according to an embodiment of the present invention.
Detailed Description
The invention provides a separation and purification system of 1, 4-butanediol, which is shown in the figure 1. The system comprises a heavy-removal tower, a stripping tower, an extraction rectifying tower and a solvent regeneration tower. Specifically, the heavy-removal tower is a tower for separating crude 1, 4-butanediol containing 1, 4-butanediol after esterification, hydrogenation and light component removal of maleic anhydride. The heavy-removal tower is respectively connected with the stripping tower and the solvent regeneration tower. Separating the crude 1, 4-butanediol in a heavy-removal tower, and extracting light components such as gamma-butyrolactone, unreacted dimethyl succinate and the like from the tower top; a mixture a containing 1, 4-butanediol and 2- (4-hydroxybutoxy) tetrahydrofuran is extracted from the side stream; 2- (4-hydroxy-butoxy) tetrahydrofuran and other heavy components are extracted from the bottom of the column. The mixture a from the side stream is directly fed into the stripping column for separation.
The stripping tower is a tower for separating a mixture a extracted from the side line of the heavy-removal tower, and the bottom of the stripping tower is connected with the extractive distillation tower. In the process of separating the mixture a in a stripping tower, 1, 4-butanediol containing light components such as gamma-butyrolactone and the like is extracted from the top of the stripping tower, high-purity 1, 4-butanediol is extracted from the side line, and 1, 4-butanediol rich in 2- (4-hydroxybutoxy) tetrahydrofuran is extracted from the bottom of the stripping tower.
The extraction rectifying tower is a tower for separating the 1, 4-butanediol which is rich in 2- (4-hydroxybutoxy) tetrahydrofuran and is extracted from the bottom of the stripping tower, and the bottom of the extraction rectifying tower is connected with the solvent regeneration tower. In the process of separating 1, 4-butanediol rich in 2- (4-hydroxy butoxy) tetrahydrofuran in an extraction rectifying tower, ultra-high-purity 1, 4-butanediol is obtained at the top of the extraction rectifying tower, and the purity of the 1, 4-butanediol is more than 99.99 percent; a mixture b containing 1, 4-butanediol, 2- (4-hydroxybutoxy) tetrahydrofuran and extractant is taken off at the bottom.
The solvent regeneration tower is a tower for separating a mixture b extracted from the bottom of the extraction rectifying tower, and the top and the bottom of the solvent regeneration tower are respectively connected with the de-weight tower and the extraction rectifying tower. In the process of separating the mixture b in a solvent regeneration tower, a mixture c of 1, 4-butanediol and 2- (4-hydroxybutoxy) tetrahydrofuran is produced at the top of the tower, and the mixture c is directly returned to the middle lower part of the de-weight tower for separation; and (3) extracting a regenerated extractant from the bottom of the tower, cooling the regenerated extractant, and entering the upper part of the extractive distillation tower to participate in extractive distillation.
The invention also provides a separation and purification method of the 1, 4-butanediol, which is specifically described in the following way by specific examples.
Example 1
The embodiment of the invention provides a separation and purification method of 1, 4-butanediol, which comprises the following steps:
s101: crude 1, 4-butanediol is separated in a de-heavies column. Wherein the content of 1, 4-butanediol is 80.5wt%, the content of 2- (4-hydroxy butoxy) tetrahydrofuran is 0.3wt%, the content of light component is 17.0wt%, and the content of the rest heavy component is 2.2wt%. The top of the heavy-removal tower is used for extracting light components such as gamma-butyrolactone, unreacted dimethyl succinate and the like; a mixture a containing 1, 4-butanediol and 2- (4-hydroxybutoxy) tetrahydrofuran is extracted from the side stream; 2- (4-hydroxy-butoxy) tetrahydrofuran and other heavy components are extracted from the bottom of the column. The packing height of the heavy-duty removal tower is 50 theoretical plates, the operating pressure is 10kPa, the reflux ratio is 8, the temperature of the tower top is 180 ℃, the temperature of the tower bottom is 200 ℃, and the concentration of 1, 4-butanediol in the heavy component of the tower bottom is lower than 20wt%.
S102: the mixture a extracted from the side line of the heavy-removal tower directly enters a stripping tower for separation. Wherein, the tower top is used for extracting 1, 4-butanediol containing light components such as gamma-butyrolactone, the lateral line is used for extracting 1, 4-butanediol with high purity, and the tower bottom is used for extracting 1, 4-butanediol rich in 2- (4-hydroxy butoxy) tetrahydrofuran. And (3) re-feeding the 1, 4-butanediol containing light components such as gamma-butyrolactone and the like extracted from the tower top into a heavy-removal tower for separation. The purity of the 1, 4-butanediol at the side stream is more than 99.9%. The concentration of 2- (4-hydroxybutoxy) tetrahydrofuran in the 1, 4-butanediol product taken off at the bottom was 2.5% by weight. The packing height of the stripping column is 40 theoretical plates, the operating pressure is 10kPa, the reflux ratio is 10, the top temperature is 160 ℃, and the bottom temperature is 190 ℃.
S103: and (3) feeding the 1, 4-butanediol product extracted from the bottom of the stripping tower into an extraction rectifying tower for separation. Wherein, ultra-high-purity 1, 4-butanediol is extracted from the tower top, and the purity of the 1, 4-butanediol is more than 99.99 percent; a mixture b containing 1, 4-butanediol, 2- (4-hydroxybutoxy) tetrahydrofuran and extractant is taken off at the bottom. The packing height of the extraction rectifying tower is 60 theoretical plates, the operating pressure is 10kPa, the reflux ratio is 10, the solvent ratio is 5, the temperature of the extractant entering the tower is 80 ℃, the temperature of the tower top is 160 ℃, the temperature of the tower bottom is 200 ℃, and the purity of the 1, 4-butanediol extracted from the tower top is more than 99.99wt%. The extractant in the extractive distillation column comprises dioctyl phthalate, o-nitroanisole and 2- (4-methoxyphenyl) -tetrahydrofuran, wherein the dioctyl phthalate accounts for 40wt%, the o-nitroanisole accounts for 30wt%, and the 2- (4-methoxyphenyl) -tetrahydrofuran accounts for 30wt%.
S104: and (3) the mixture b extracted from the bottom of the separation tower of the extraction rectifying tower enters a solvent regeneration tower for separation. Wherein, the mixture c of 1, 4-butanediol and 2- (4-hydroxy butoxy) tetrahydrofuran is taken out from the top of the tower, and the regenerated extractant is taken out from the bottom of the tower. The packing height of the solvent regeneration tower is 40 theoretical plates, the operating pressure is 10kPa, the reflux ratio is 3, the tower top temperature is 160 ℃, and the tower bottom temperature is 220 ℃.
S105: the mixture c extracted from the top of the solvent regeneration tower directly returns to the middle lower part of the de-weight tower for separation; the regenerated extractant extracted from the bottom of the tower enters the upper part of the extractive distillation tower to participate in extractive distillation after being cooled.
Example 2
The embodiment of the invention provides a separation and purification method of 1, 4-butanediol, which comprises the following steps:
s201: crude 1, 4-butanediol is separated in a de-heavies column. Wherein the content of 1, 4-butanediol is 80.5wt%, the content of 2- (4-hydroxy butoxy) tetrahydrofuran is 0.3wt%, the content of light component is 17.0wt%, and the content of the rest heavy component is 2.2wt%. The top of the heavy-removal tower is used for extracting light components such as gamma-butyrolactone, unreacted dimethyl succinate and the like; a mixture a containing 1, 4-butanediol and 2- (4-hydroxybutoxy) tetrahydrofuran is extracted from the side stream; 2- (4-hydroxy-butoxy) tetrahydrofuran and other heavy components are extracted from the bottom of the column. The packing height of the heavy-removal tower is 10 theoretical plates, the operating pressure is 5kPa, the reflux ratio is 5, the temperature of the tower top is 160 ℃, the temperature of the tower bottom is 180 ℃, and the concentration of 1, 4-butanediol in the heavy component of the tower bottom is lower than 20wt%.
S202: the mixture a extracted from the side line of the heavy-removal tower directly enters a stripping tower for separation. Wherein, the tower top is used for extracting 1, 4-butanediol containing light components such as gamma-butyrolactone, the lateral line is used for extracting 1, 4-butanediol with high purity, and the tower bottom is used for extracting 1, 4-butanediol rich in 2- (4-hydroxy butoxy) tetrahydrofuran. And (3) re-feeding the 1, 4-butanediol containing light components such as gamma-butyrolactone and the like extracted from the tower top into a heavy-removal tower for separation. The purity of the 1, 4-butanediol at the side stream is more than 99.9%. The concentration of 2- (4-hydroxybutoxy) tetrahydrofuran in the 1, 4-butanediol product taken off at the bottom was 0.5% by weight. The packing height of the stripping column is 20 theoretical plates, the operating pressure is 5kPa, the reflux ratio is 5, the top temperature is 140 ℃, and the bottom temperature is 180 ℃.
S203: and (3) feeding the 1, 4-butanediol product extracted from the bottom of the stripping tower into an extraction rectifying tower for separation. Wherein, ultra-high-purity 1, 4-butanediol is extracted from the tower top, and the purity of the 1, 4-butanediol is more than 99.99 percent; a mixture b containing 1, 4-butanediol, 2- (4-hydroxybutoxy) tetrahydrofuran and extractant is taken off at the bottom. The packing height of the extraction rectifying tower is 30 theoretical plates, the operating pressure is 1kPa, the reflux ratio is 5, the solvent ratio is 3, the temperature of the extractant entering the tower is 50 ℃, the temperature of the tower top is 120 ℃, the temperature of the tower bottom is 180 ℃, and the purity of the 1, 4-butanediol extracted from the tower top is more than 99.99wt%. The extractant in the extractive distillation column comprises dioctyl phthalate, o-nitroanisole and 2- (4-methoxyphenyl) -tetrahydrofuran, wherein the dioctyl phthalate accounts for 40wt%, the o-nitroanisole accounts for 20wt%, and the 2- (4-methoxyphenyl) -tetrahydrofuran accounts for 40wt%.
S204: and (3) the mixture b extracted from the bottom of the separation tower of the extraction rectifying tower enters a solvent regeneration tower for separation. Wherein, the mixture c of 1, 4-butanediol and 2- (4-hydroxy butoxy) tetrahydrofuran is taken out from the top of the tower, and the regenerated extractant is taken out from the bottom of the tower. The packing height of the solvent regeneration tower is 20 theoretical plates, the operating pressure is 1kPa, the reflux ratio is 1, the top temperature is 120 ℃, and the bottom temperature is 200 ℃.
S205: the mixture c extracted from the top of the solvent regeneration tower directly returns to the middle lower part of the de-weight tower for separation; the regenerated extractant extracted from the bottom of the tower enters the upper part of the extractive distillation tower to participate in extractive distillation after being cooled.
Example 3
The embodiment of the invention provides a separation and purification method of 1, 4-butanediol, which comprises the following steps:
s301: crude 1, 4-butanediol is separated in a de-heavies column. Wherein the content of 1, 4-butanediol is 80.5wt%, the content of 2- (4-hydroxy butoxy) tetrahydrofuran is 0.3wt%, the content of light component is 17.0wt%, and the content of the rest heavy component is 2.2wt%. The top of the heavy-removal tower is used for extracting light components such as gamma-butyrolactone, unreacted dimethyl succinate and the like; a mixture a containing 1, 4-butanediol and 2- (4-hydroxybutoxy) tetrahydrofuran is extracted from the side stream; 2- (4-hydroxy-butoxy) tetrahydrofuran and other heavy components are extracted from the bottom of the column. The packing height of the heavy-duty removal tower is 50 theoretical plates, the operating pressure is 25kPa, the reflux ratio is 10, the temperature of the top of the tower is 200 ℃, the temperature of the bottom of the tower is 220 ℃, and the concentration of 1, 4-butanediol in the heavy components of the bottom of the tower is lower than 20wt%.
S302: the mixture a extracted from the side line of the heavy-removal tower directly enters a stripping tower for separation. Wherein, the tower top is used for extracting 1, 4-butanediol containing light components such as gamma-butyrolactone, the lateral line is used for extracting 1, 4-butanediol with high purity, and the tower bottom is used for extracting 1, 4-butanediol rich in 2- (4-hydroxy butoxy) tetrahydrofuran. And (3) re-feeding the 1, 4-butanediol containing light components such as gamma-butyrolactone and the like extracted from the tower top into a heavy-removal tower for separation. The purity of the 1, 4-butanediol at the side stream is more than 99.9%. The concentration of 2- (4-hydroxybutoxy) tetrahydrofuran in the 1, 4-butanediol product taken off at the bottom was 5% by weight. The packing height of the stripping column is 50 theoretical plates, the operating pressure is 30kPa, the reflux ratio is 10, the top temperature is 180 ℃, and the bottom temperature is 200 ℃.
S303: and (3) feeding the 1, 4-butanediol product extracted from the bottom of the stripping tower into an extraction rectifying tower for separation. Wherein, ultra-high-purity 1, 4-butanediol is extracted from the tower top, and the purity of the 1, 4-butanediol is more than 99.99 percent; a mixture b containing 1, 4-butanediol, 2- (4-hydroxybutoxy) tetrahydrofuran and extractant is taken off at the bottom. The packing height of the extraction rectifying tower is 60 theoretical plates, the operating pressure is 10kPa, the reflux ratio is 10, the solvent ratio is 10, the temperature of the extractant entering the tower is 100 ℃, the temperature of the tower top is 180 ℃, the temperature of the tower bottom is 220 ℃, and the purity of the 1, 4-butanediol extracted from the tower top is more than 99.99wt%. The extractant in the extractive distillation column comprises dioctyl phthalate, o-nitroanisole and 2- (4-methoxyphenyl) -tetrahydrofuran, wherein the dioctyl phthalate accounts for 50wt%, the o-nitroanisole accounts for 00wt%, and the 2- (4-methoxyphenyl) -tetrahydrofuran accounts for 50wt%.
S304: and (3) the mixture b extracted from the bottom of the separation tower of the extraction rectifying tower enters a solvent regeneration tower for separation. Wherein, the mixture c of 1, 4-butanediol and 2- (4-hydroxy butoxy) tetrahydrofuran is taken out from the top of the tower, and the regenerated extractant is taken out from the bottom of the tower. The packing height of the solvent regeneration tower is 50 theoretical plates, the operating pressure is 10kPa, the reflux ratio is 10, the top temperature is 180 ℃, and the bottom temperature is 240 ℃.
S305: the mixture c extracted from the top of the solvent regeneration tower directly returns to the middle lower part of the de-weight tower for separation; the regenerated extractant extracted from the bottom of the tower enters the upper part of the extractive distillation tower to participate in extractive distillation after being cooled.
Example 4
The embodiment of the invention provides a separation and purification method of 1, 4-butanediol, which has the specific flow similar to that of the embodiment 1, and the specific flow is that the ratio of dioctyl phthalate, o-nitroanisole and 2- (4-methoxyphenyl) -tetrahydrofuran is different, and the specific flow is 1:5:4.
Example 5
The embodiment of the invention provides a separation and purification method of 1, 4-butanediol, which has the specific flow similar to that of the embodiment 1, and the specific flow is that the ratio of dioctyl phthalate, o-nitroanisole and 2- (4-methoxyphenyl) -tetrahydrofuran is different, and the specific flow is 5:5:0.
Example 6
The embodiment of the invention provides a separation and purification method of 1, 4-butanediol, which has the specific flow similar to that of the embodiment 1, and the specific flow of the method is that the ratio of dioctyl phthalate, o-nitroanisole and 2- (4-methoxyphenyl) -tetrahydrofuran is different, and the specific flow is 5:1:4.
Example 7
The embodiment of the invention provides a separation and purification method of 1, 4-butanediol, which has the specific flow similar to that of the embodiment 1, and the specific flow is that the ratio of dioctyl phthalate, o-nitroanisole and 2- (4-methoxyphenyl) -tetrahydrofuran is different, and the specific flow is 4:5:1.
After the process shown in the above examples 1 to 7 was stably operated, the purity and recovery rate of 1, 4-butanediol produced in steps S02, S03 in each example were tested, and the specific results are shown in Table 1.
Table 1: purity and recovery of 1, 4-butanediol
| Examples | Recovery of 1, 4-butanediol | High purity 1, 4-butanediol | Ultrapure 1, 4-butanediol purity |
| 1 | 99.1％ | 99.91％ | 99.99％ |
| 2 | 99.0％ | 99.90％ | 99.98％ |
| 3 | 99.1％ | 99.90％ | 99.84％ |
| 4 | 99.2％ | 99.91％ | 99.51％ |
| 5 | 99.1％ | 99.91％ | 99.40％ |
| 6 | 99.2％ | 99.90％ | 99.63％ |
| 7 | 99.0％ | 99.91％ | 99.53％ |
As can be seen from Table 1, after the process shown in examples 1 to 7 was stably operated, the purity of 1, 4-butanediol obtained in step S02 was over 99.9%, and the purity of 1, 4-butanediol obtained in step S03 was 99.99%. In addition, the recovery rate of the 1, 4-butanediol can reach more than 99 percent. Therefore, the separation and purification method of the 1, 4-butanediol provided by the invention can effectively separate and purify the 1, 4-butanediol and the 2- (4-hydroxybutoxy) tetrahydrofuran to obtain the ultra-high-purity 1, 4-butanediol.
Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure of the invention herein. This invention is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.
It is further understood that the use of relational terms such as "first" and "second", and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. The invention is not limited to the precise construction which has been described above and shown in the drawings, and various modifications and changes may be made without departing from the scope thereof. The scope of the invention is limited only by the appended claims.
Claims (1)
1. The separation and purification method of the 1, 4-butanediol is characterized by comprising the following steps:
separating crude 1, 4-butanediol in a heavy-duty removal column, and laterally withdrawing a mixture a containing 1, 4-butanediol and 2- (4-hydroxybutoxy) tetrahydrofuran; the packing height in the weight-removing tower is 10-50 theoretical plates, the operating pressure is 5-25kPa, the reflux ratio is 5-10, the temperature of the tower top is 160-200 ℃, the temperature of the tower bottom is 180-220 ℃, and the concentration of 1, 4-butanediol in the tower bottom heavy component is lower than 20wt%;
separating the mixture a in a stripping tower, laterally extracting 1, 4-butanediol, and extracting 1, 4-butanediol rich in 2- (4-hydroxybutoxy) tetrahydrofuran from the bottom of the stripping tower; the packing height in the stripping tower is 20-50 theoretical plates, the operating pressure is 5-30kPa, the reflux ratio is 5-10, the temperature of the top of the tower is 140-180 ℃, the temperature of the bottom of the tower is 180-200 ℃, and the purity of the 1, 4-butanediol extracted from the side line is more than 99.9wt%;
the bottom product of the stripping tower enters an extraction rectifying tower for separation, 1, 4-butanediol is extracted from the top of the stripping tower, and a mixture b containing 1, 4-butanediol, 2- (4-hydroxybutoxy) tetrahydrofuran and an extractant is extracted from the bottom of the stripping tower; the height of the packing in the extraction rectifying tower is 30-60 theoretical plates, the operating pressure is 1-10kPa, the reflux ratio is 5-10, the solvent ratio is 3-10, the temperature of the extractant entering the tower is 50-100 ℃, the temperature of the tower top is 120-180 ℃, the temperature of the tower bottom is 180-220 ℃, and the purity of the 1, 4-butanediol extracted from the tower top is more than 99.99wt%; the extractant is dioctyl phthalate, o-nitroanisole and 2- (4-methoxyphenyl) -tetrahydrofuran;
separating the mixture b in a solvent regeneration tower, and collecting a mixture c of 1, 4-butanediol and 2- (4-hydroxybutoxy) tetrahydrofuran at the top of the solvent regeneration tower; the regenerated extractant is extracted from the bottom of the tower; the packing height in the solvent regeneration tower is 20-50 theoretical plates, the operating pressure is 1-10kPa, the reflux ratio is 1-10, the temperature of the top of the tower is 120-180 ℃, the temperature of the bottom of the tower is 200-240 ℃, the concentration of 2- (4-hydroxy butoxy) tetrahydrofuran in the mixture c is more than 10wt%, and the purity of the regenerated extractant is more than 99.9wt%;
and the mixture c enters the de-weight tower for separation, and the regenerated extractant enters the extractive distillation tower.
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