CN111689838A - Method for adsorbing and separating p-cresol and m-cresol - Google Patents
Method for adsorbing and separating p-cresol and m-cresol Download PDFInfo
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Abstract
A method for separating p-cresol and m-cresol by adsorption comprises the steps of introducing a mixture of p-cresol and m-cresol into an adsorption zone of a liquid-phase simulated moving bed to contact with an adsorbent, adsorbing the p-cresol by the adsorbent, removing the m-cresol as raffinate, introducing a desorption agent into the adsorbent, and desorbing adsorbed components to obtain extract, wherein the liquid-phase simulated moving bed comprises the following four functional zones: the adsorption and desorption device comprises a desorption zone, a purification zone, an adsorption zone and a buffer zone, wherein the temperature of adsorption raw materials introduced into the adsorption zone is 100-230 ℃, the temperature of desorption agents introduced into the desorption zone is 120-250 ℃, the temperature of the desorption agents introduced into the desorption zone is controlled to be 10-100 ℃ higher than the temperature of the adsorption raw materials introduced into the adsorption zone, active components of the adsorbents are selected from any one of BaX, BaKX and KY molecular sieves, and the desorption agents are 30-96 mass percent of C3～C5And 4 to 70 mass% of C7～C9A mixture of alkanes. The method is used for suckingThe mixture of p-cresol and m-cresol is separated to obtain high purity p-cresol and m-cresol products.
Description
Technical Field
The invention relates to an adsorption separation method of p-cresol and m-cresol, in particular to a method for producing p-cresol products and m-cresol products by utilizing liquid-phase simulated moving bed adsorption separation.
Background
Cresol is an important intermediate in fine chemistry and includes three isomers, ortho-cresol, meta-cresol and para-cresol. Direct extraction from natural sources and chemical synthesis are the main routes to cresol, but generally a mixture of the three isomers is obtained. The boiling point difference of o-cresol, m-cresol and p-cresol is large (more than 10 ℃), and the o-cresol, the m-cresol and the p-cresol are usually obtained by separation by adopting a rectification method; however, m-cresol and p-cresol have very close boiling points and have a difference of less than 1 ℃, so that it is difficult to separate them by conventional distillation.
In the fine chemical industry, when p-cresol and m-cresol are used as intermediates, the purity requirement is high, so an effective method for separating the two isomers is needed. The separation methods disclosed in the prior art include a complexation method, an alkylation method, a crystallization method, and the like.
CN1127241A discloses a process for separating and purifying p-cresol by a complex extraction crystallization method, which comprises the steps of taking piperazine as an extracting agent, taking n-butyl ether as a solvent, enabling the piperazine to selectively react with the p-cresol to generate a complex, and cooling to 20-minus 20 ℃ for crystallization. Separating the complex crystal, dissolving in water, adding n-butyl ether to make p-cresol enter organic phase, dissolving piperazine in water phase, separating organic phase and water phase, and rectifying organic phase to obtain high-purity p-cresol.
CN101863742A discloses a method for separating m-cresol and p-cresol mixtures, which comprises the steps of carrying out alkylation reaction on m-cresol and p-cresol mixtures serving as raw materials in the presence of an alkylating agent isobutene or methyl tert-butyl ether and a catalyst to obtain a mixed solution of 2-tert-butyl-p-cresol and 6-tert-butyl-m-cresol, rectifying the mixed solution to obtain high-purity 2-tert-butyl-p-cresol and 6-tert-butyl-m-cresol, and then respectively carrying out dealkylation reaction and rectification dealkylation to obtain a kettle solution, thereby obtaining high-purity m-cresol and p-cresol products.
US4032581 discloses a high pressure crystallization separation process for m-and p-cresol mixtures, wherein the m-and p-cresol mixture is pressurized at a first pressure zone at a certain temperature to obtain a crystalline solid phase and a liquid phase of p-cresol or m-cresol, the crystalline phase is transferred to a second pressure zone having a lower pressure, the crystalline solid is melted by heating, and the liquefied crystalline phase is discharged to obtain the high purity cresol isomers.
Disclosure of Invention
The invention aims to provide a method for adsorbing and separating p-cresol and m-cresol, which is used for adsorbing and separating a mixture of p-cresol and m-cresol to obtain high-purity p-cresol and m-cresol products respectively.
The invention provides a method for adsorbing and separating p-cresol and m-cresol, which comprises the steps of introducing a mixture of p-cresol and m-cresol as an adsorption raw material into an adsorption zone of a liquid-phase simulated moving bed to contact with an adsorbent, adsorbing the p-cresol by the adsorbent, not adsorbing the m-cresol, taking out the mixture as raffinate, introducing a desorption agent into the adsorbent, desorbing adsorbed components to obtain extract, wherein the liquid-phase simulated moving bed comprises the following four functional zones:
a desorption area: is positioned in the area between the desorption agent injection point and the extract liquid extraction point,
a purification area: is positioned in the area between the extraction point of the extract and the injection point of the adsorption raw material,
an adsorption zone: located in the region between the adsorption feed injection point and the raffinate withdrawal point,
a buffer area: in the region between the desorbent injection point and the raffinate withdrawal point,
the temperature of the adsorption raw material introduced into the adsorption zone is 100-230 ℃, the temperature of the desorption agent introduced into the desorption zone is 120-250 ℃, and the temperature of the desorption agent introduced into the desorption zone is controlled to be higher than the temperature of the adsorption raw material introduced into the adsorption zoneThe temperature of the adsorbent is 10-100 ℃, the active component of the adsorbent is selected from any one of BaX, BaKX and KY molecular sieves, and the desorbent is 30-96 mass percent of C3～C5And 4 to 70 mass% of C7～C9A mixture of alkanes.
The method uses proper amount of C3～C5Fatty alcohol of (2) and (C)7～C9The mixture of the alkane is a desorption agent, the temperature of the desorption agent introduced into the desorption area is controlled to be 10-100 ℃ higher than the temperature of the adsorption raw material introduced into the adsorption area, the adsorption and separation efficiency of the p-cresol and the m-cresol can be effectively improved, and meanwhile, high-purity p-cresol and m-cresol products are produced.
Drawings
FIG. 1 is a schematic diagram of a liquid phase simulated moving bed adsorption unit comprising four functional zones according to the present invention.
Detailed Description
The method adopts a liquid phase simulated moving bed to adsorb and separate the paracresol and the metacresol, a mixture of the paracresol and the metacresol with the temperature of 100-230 ℃ is used as a raw material to be injected into an adsorption area and contacted with an adsorbent, the paracresol is adsorbed by the adsorbent to form an adsorption phase, and the nonadsorbed metacresol is taken out as raffinate; injecting a desorption agent with the temperature of 120-250 ℃ from the desorption area, removing p-cresol in the adsorbent purified by the purification area, and taking out the adsorbent as extract from the purification area; the extract and raffinate are respectively subjected to desorption agent separation to obtain high-purity p-cresol and m-cresol. The injection temperature of the desorption agent is higher than that of the raw materials, so that the p-cresol and the m-cresol in the raw materials can be separated by fully utilizing the characteristic of high low-temperature selectivity of the adsorbent, and the yield of the p-cresol and the purity of the m-cresol can be improved by fully utilizing the excellent mass transfer performance of the adsorbent at higher temperature and the excellent desorption effect brought by high temperature. In addition, the used desorption agent is 30-96 mass percent of C3～C5And 4 to 70 mass% of C7～C9A mixture of alkanes by adding to said alcohol an appropriate amount of C7～C9The alkane can effectively adjust the relative selectivity of the desorption agent to the p-cresol and the m-cresol, and is beneficial to the separation of the two components.
In the method, the temperature of introducing the adsorption raw material into the adsorption zone is preferably 100-170 ℃, and the temperature of introducing the desorption agent into the desorption zone is preferably 180-250 ℃. Preferably, the temperature of the desorption agent introduced into the desorption zone is controlled to be 20-100 ℃ higher than the temperature of the adsorption raw material introduced into the adsorption zone.
C in the desorbent of the invention3～C5The fatty alcohol can be n-propanol, n-butanol or n-pentanol, and the C is7～C9The alkane may be n-heptane, n-octane or n-nonane.
The desorbing agent is preferably 50-96 mass% of C3～C5And 4 to 50 mass% of C7～C9A mixture of alkanes.
In the method, the mass flow ratio of the desorption agent and the adsorption raw material introduced into the liquid-phase simulated moving bed is 3.0-10, preferably 3.0-7.5. The liquid phase simulated moving bed comprises a plurality of bed layers, the number of the preferable bed layers is 6-24, and the operating pressure of the liquid phase simulated moving bed is 0.1-3.0 MPa, preferably 0.6-2.0 MPa.
In the invention, the preferred space velocity of the adsorption raw material relative to the feeding volume of the adsorbent is 0.1-0.5 h-1. If the space velocity of the feed relative to the adsorbent is outside this range, only a cresol isomer product of higher purity can be obtained, by which is meant p-cresol or m-cresol with a purity of more than 98 mass%, preferably more than 99 mass%.
In the method, the adsorption active component in the adsorbent is any one of BaX, BaKX and KY molecular sieves, and the adsorbent can also contain a binder or a matrix formed by the binder after crystal transformation, wherein the content of the active component in the adsorbent can be 90-100 mass%. The mole ratio of silicon oxide to aluminum oxide of the X molecular sieve is preferably 2.05-2.95, and the mole ratio of silicon oxide to aluminum oxide of the Y molecular sieve is preferably 4-7. In BaKX molecular sieves, BaO/K2The molar ratio of O is 3-50: 1. preferably, the weight ratio is 3-20: 1. the adsorbent is preferably in a small ball shape, and the diameter of the adsorbent is preferably 0.1 mm-1.2 mm.
In the method of the present invention, the preparation method of the adsorbent comprises the following steps:
(1) mixing a NaX or NaY molecular sieve with a binder according to the weight ratio of 90-95: 5-10, adding a forming assistant, uniformly mixing, spraying water while rolling the mixed powder to prepare small balls with the diameter of 0.1-1.2 mm, drying at 60-120 ℃ for 2-24 hours, and roasting at 500-560 ℃ for 4-10 hours.
(2) Performing alkali treatment on the roasted pellets with an aqueous solution of NaOH and sodium silicate or an aqueous solution of NaOH at a temperature of 80-120 ℃, drying to obtain basic pellets,
(3) carrying out cation exchange on the basic pellet containing the X molecular sieve by using a solution containing soluble barium salt and sylvite or a soluble barium salt solution, and preparing a BaKX or BaX adsorbent after activation; and (3) carrying out cation exchange on the basic pellet containing the Y molecular sieve by using a sylvite solution, and activating to prepare the KY adsorbent.
In the method, kaolin is preferably selected as the binder in the step (1), corn starch or sesbania powder is preferably selected as the forming aid, the addition amount of the forming aid is preferably 0.5-5% of the mass of the mixed powder, and the addition amount of water is preferably 10-30% of the mass of the mixed powder.
(2) In the step (1), the pellets prepared by NaX in the step (1) are subjected to alkali treatment by using an aqueous solution of NaOH and sodium silicate to crystallize a binder in situ into an X molecular sieve, and the concentration of NaOH in the solution is preferably 1.0-2.0 mol/L, SiO2The concentration is preferably 2-16 g/L. And (3) carrying out alkali treatment on the pellets prepared by using NaY in the step (1) by using an aqueous solution of NaOH, wherein the concentration of NaOH in the solution is preferably 1.0-2.0 mol/L.
(3) The soluble barium salt is preferably barium nitrate or barium chloride, the potassium salt is preferably potassium nitrate or potassium chloride, and the ion exchange is preferably carried out to such an extent that the degree of exchange of the cation sites of the adsorbent is more than 97 mol%. The activation temperature of the small balls after ion exchange is preferably 170-300 ℃.
The water content of the adsorbent measured by burning the adsorbent at 600 ℃ for 2 hours is 2.0-6.0 mass%, the water content measured by burning the adsorbent at 600 ℃ for 2 hours is preferably 3.0-6.0 mass% when the active component of the adsorbent is an X molecular sieve, and the water content measured by burning the adsorbent at 600 ℃ for 2 hours is preferably 2.0-5.0 mass% when the active component of the adsorbent is a Y molecular sieve.
In order to increase the desorption effect, the desorption agent preferably contains 20-120 ppm of water.
The present invention is further illustrated by the following examples, but the present invention is not limited thereto.
Example 1
The following examples prepare adsorbents.
Mixing 9.4kg of NaX molecular sieve with the molar ratio of silicon oxide to aluminum oxide of 2.3, 0.6kg of kaolin and 0.2kg of corn starch uniformly, putting the mixture into a sugar coating pot, spraying 2.2kg of water while rolling, rolling and molding to prepare small balls with the diameter of 0.3-0.8 mm, drying at 100 ℃ for 4h, and roasting at 540 ℃ for 6 h.
Soaking the roasted pellets in 20 liters of aqueous solution containing NaOH and sodium silicate at 98 ℃ for alkali treatment for 5 hours to convert kaolin into an X molecular sieve in situ, wherein the concentration of NaOH in the solution for alkali treatment is 1.5mol/L, SiO2The concentration is 10g/L, and the pellets after the alkali treatment are washed by deionized water until the pH value of a washing solution is lower than 10 to obtain basic pellets.
Mixing the above basic pellets with a solution containing barium chloride and potassium chloride at 90 deg.C for 6 hr-1Ion exchange for 6 hours at the volume space velocity of (1), until the cation exchange degree is more than 97 mol%, then heating to 220 ℃ in dry air and activating for 1.5 hours to obtain the adsorbent A, wherein the BaKX molecular sieve content is 97.7 mass%, and the rest is a matrix formed after crystal transformation of kaolin, BaO/K2The molar ratio of O was 8.2, and the water content of the adsorbent A measured by burning at 600 ℃ for 2 hours was 5.3% by mass.
Example 2
Mixing 9.2kg of NaX molecular sieve with the molar ratio of silicon oxide to aluminum oxide of 2.6, 0.8kg of kaolin and 0.3kg of corn starch uniformly, putting the mixture into a sugar coating pot, spraying 2.2kg of water while rolling, rolling and molding to prepare small balls with the diameter of 0.3-0.8 mm, drying at 100 ℃ for 4h, and roasting at 500 ℃ for 6 h.
Soaking the above calcined pellet in 20L aqueous solution containing NaOH and sodium silicate at 98 deg.C for alkali treatment for 5 hr, wherein the concentration of NaOH in the solution for alkali treatment is 1.5mol/L, SiO2The concentration is 4g/L, and the pellets after the alkali treatment are separatedWashing the seed balls with water until the pH value of the washing liquid is lower than 10 to obtain the basic balls.
The basic pellets are treated with barium nitrate solution at 95 ℃ for 5.5h-1Ion exchange is carried out for 6 hours under the volume space velocity of the adsorbent until the barium ion exchange degree is more than 97mol percent, and then the adsorbent is activated for 2 hours by heating to 240 ℃ in dry air to obtain the adsorbent B. In the adsorbent B, the BaX molecular sieve content was 97.2 mass%, the remainder was a matrix formed by the transcrystallization of kaolin, and the adsorbent B had a water content of 3.5 mass% as measured by firing at 600 ℃ for 2 hours.
Example 3
Mixing 9.2kg of NaY molecular sieve with the molar ratio of silicon oxide to aluminum oxide of 5.1, 0.8kg of kaolin and 0.4kg of corn starch uniformly, putting the mixture into a sugar coating pot, spraying 1.9kg of water while rolling, rolling and molding to prepare small balls with the diameter of 0.3-0.8 mm, drying at 100 ℃ for 4h, and roasting at 540 ℃ for 6 h.
And (3) soaking the roasted pellets in 20 liters of NaOH aqueous solution with the concentration of 1.5mol/L at 98 ℃ for alkali treatment for 5 hours, and washing the alkali-treated pellets with deionized water until the pH value of a washing solution is lower than 10 to obtain the basic pellets.
Mixing the above basic pellets with potassium chloride solution at 95 deg.C for 6 hr-1The ion exchange is carried out for 8 hours at the volume space velocity until the exchange degree of potassium ions is more than 97mol percent, and then the temperature is raised to 190 ℃ in dry air for activation for 2 hours to obtain an adsorbent C and the adsorbent C. In the adsorbent C, the content of the KY molecular sieve is 92.5 mass%, the balance is kaolin, and the water content of the adsorbent C is 2.8 mass% when the adsorbent C is burned at 600 ℃ for 2 hours.
Example 4
The following example is the adsorptive separation of a mixture of p-cresol and m-cresol using a simulated moving bed.
The experiment was carried out using a small simulated moving bed apparatus as shown in FIG. 1. The device comprises 12 adsorption columns connected in series, the length of each adsorption column is 377 millimeters, the inner diameter of each adsorption column is 30 millimeters, and the total volume of an adsorbent is 3200 mL.
The 12 adsorption columns connected in series are filled with adsorbent, and a circulating pump (not shown in the figure) is connected between two columns to provide power for fluid circulation in the columns. Four materials of a desorption agent, extract liquid, adsorption raw materials and raffinate divide the adsorption columns into four areas: 2 columns between the desorbent and the extract are desorption zones, 5 columns between the extract and the raw material are purification zones, 3 columns between the raw material and the raffinate are adsorption zones, and 2 columns between the raffinate and the desorbent are buffer zones.
The raw material used for the adsorption contained 30.3 mass% of p-cresol, 69.6 mass% of m-cresol, and 0.1 mass% of other components.
The adsorbent A prepared in example 1 was packed in an adsorption column, and the desorbent was a mixture of 95 mass% of n-pentanol and 5 mass% of n-octane containing 80ppm of water. Controlling the feeding temperature of the introduced adsorption raw material to be 165 ℃, the feeding temperature of the desorption agent to be 185 ℃, the pressure of the simulated moving bed to be 1.2MPa, the flow rate of the desorption agent to be 3318g/h, the flow rate of the extract to be 1801g/h, the flow rate of the adsorption raw material to be 948g/h, the flow rate of the raffinate to be 2465g/h, and the feeding volume space velocity of the adsorption raw material to the adsorbent to be 0.327h-1. The desorbent in the extract was removed to obtain a p-cresol product with a purity of 99.7 mass%, and the desorbent in the raffinate was removed to obtain a m-cresol product with a purity of 99.5 mass%.
Example 5
A mixture of p-cresol and m-cresol was isolated by adsorption as in example 4, except that the temperature of the feed for adsorption was controlled to 145 ℃, the temperature of the feed for desorption was controlled to 195 ℃, the feed flow rate was 995g/h, the raffinate flow rate was 2512g/h, and the feed volume space velocity of the adsorption feed relative to the adsorbent was 0.335h-1. The purity of the p-cresol product obtained after the desorption agent in the extract liquid is removed is 99.7 mass%, and the purity of the m-cresol product obtained after the desorption agent in the raffinate is removed is 99.6 mass%.
Example 6
The mixture of p-cresol and m-cresol was separated by adsorption as in example 4, except that the temperature of the feed for adsorption was controlled to 120 ℃ and the temperature of the feed for desorption was controlled to 220 ℃, the feed flow rate was 1032g/h, the raffinate flow rate was 2549g/h, and the feed volume space velocity of the adsorption feed relative to the adsorbent was 0.339h-1. The purity of the p-cresol product obtained after the desorption agent in the extract liquid is removed is 99.7 mass percent, and the desorption agent in the raffinate is removedThe purity of the obtained m-cresol product was 99.6 mass%.
Example 7
A mixture of p-cresol and m-cresol was separated by adsorption in the same manner as in example 4, except that the desorbent was a mixture of 60 mass% of n-pentanol and 40 mass% of n-octane containing 45ppm of water; the flow rate of the desorption agent is 4236g/h, the flow rate of the extract is 2259g/h, the flow rate of the adsorption raw material is 948g/h, the flow rate of the raffinate is 2925g/h, and the space velocity of the adsorption raw material relative to the feeding volume of the adsorbent is 0.327h-1. The purity of the p-cresol product obtained after the desorption agent in the extract liquid is removed is 99.2 mass%, and the purity of the m-cresol product obtained after the desorption agent in the raffinate is removed is 98.3 mass%.
Example 8
The mixture of p-cresol and m-cresol was separated by adsorption by the method of example 4, except that the adsorbent B prepared in example 2 was packed in an adsorption column, and after adsorption separation, the purity of the p-cresol product obtained after removal of the desorbent from the extract was 99.3 mass%, and the purity of the m-cresol product obtained after removal of the desorbent from the raffinate was 98.6 mass%.
Example 9
The mixture of p-cresol and m-cresol was separated by adsorption by the method of example 4, except that the adsorbent C prepared in example 3 was packed in an adsorption column, and after adsorption separation, the purity of the p-cresol product obtained after removal of the desorbent from the extract was 99.0 mass%, and the purity of the m-cresol product obtained after removal of the desorbent from the raffinate was 98.1 mass%.
Example 10
A mixture of p-cresol and m-cresol was separated by adsorption in the same manner as in example 4, except that the desorbent was a mixture of 50 mass% of n-butanol and 50 mass% of n-octane containing 115ppm of water; the flow rate of the desorption agent is 3259g/h, the flow rate of the extract is 1024g/h, the flow rate of the adsorption raw material is 582g/h, the flow rate of the raffinate is 2817g/h, and the space velocity of the adsorption raw material relative to the feeding volume of the adsorbent is 0.201h-1. The purity of the p-cresol product obtained after the desorption agent in the extract liquid is removed is 99.3 mass%, and the purity of the m-cresol product obtained after the desorption agent in the raffinate is removed is 98.0 mass%.
Example 11
A mixture of p-cresol and m-cresol was separated by adsorption in the same manner as in example 4, except that the desorbent was a mixture of 35 mass% of n-propanol and 65 mass% of n-octane containing 60ppm of water; the flow rate of the desorption agent is 3552g/h, the flow rate of the extract is 780g/h, the flow rate of the adsorption raw material is 481g/h, the flow rate of the raffinate is 3253g/h, and the space velocity of the adsorption raw material relative to the feeding volume of the adsorbent is 0.166h-1. The purity of the p-cresol product obtained after the desorption agent in the extract liquid is removed is 99.0 mass%, and the purity of the m-cresol product obtained after the desorption agent in the raffinate is removed is 98.4 mass%.
Example 12
A mixture of p-cresol and m-cresol was separated by adsorption in the same manner as in example 4, except that the desorbent was a mixture of 50 mass% of n-pentanol and 50 mass% of n-octane containing 20ppm of water; the flow rate of the desorption agent is 4829g/h, the flow rate of the extract is 2283g/h, the flow rate of the adsorption raw material is 948g/h, the flow rate of the raffinate is 3494g/h, and the space velocity of the adsorption raw material relative to the feeding volume of the adsorbent is 0.327h-1. The purity of the p-cresol product obtained after the desorption agent in the extract liquid is removed is 99.0 mass%, and the purity of the m-cresol product obtained after the desorption agent in the raffinate is removed is 98.1 mass%.
Comparative example 1
A mixture of p-cresol and m-cresol was separated by adsorption in the same manner as in example 4, except that the desorbent used was a mixture of 95 mass% n-pentanol and 5 mass% toluene, and that the adsorption feed and the desorbent feed temperatures were 150 ℃. After adsorption separation, the purity of the p-cresol product obtained after the desorption agent in the extract liquid is removed is 98.5 mass%, and the purity of the m-cresol product obtained after the desorption agent in the raffinate is removed is 95.2 mass%.
Comparative example 2
A mixture of p-cresol and m-cresol was separated by adsorption in the same manner as in example 12, except that the desorbent used was a mixture of 50 mass% n-pentanol and 50 mass% toluene containing 20ppm of water, and the adsorption feed and the desorbent feed temperatures were 150 ℃ each. After adsorption separation, the purity of the p-cresol product obtained after the desorption agent in the extract liquid is removed is 92.0 mass%, and the purity of the m-cresol product obtained after the desorption agent in the raffinate is removed is 84.3 mass%.
Comparative example 3
A mixture of p-cresol and m-cresol was separated by adsorption in the same manner as in example 12, except that the desorbent used was a mixture of 50 mass% n-hexanol and 50 mass% toluene containing 20ppm of water, and that the adsorption feed and the desorbent feed temperatures were 150 ℃ each. After adsorption separation, the purity of the p-cresol product obtained after the desorption agent in the extract liquid is removed is 88.6 mass percent, and the purity of the m-cresol product obtained after the desorption agent in the raffinate is removed is 72.9 mass percent.
Claims (10)
1. A method for separating p-cresol and m-cresol by adsorption comprises the steps of introducing a mixture of p-cresol and m-cresol as an adsorption raw material into an adsorption zone of a liquid-phase simulated moving bed to contact with an adsorbent, adsorbing the p-cresol by the adsorbent, not adsorbing the m-cresol, taking out the mixture as raffinate, introducing a desorption agent into the adsorbent, and desorbing adsorbed components to obtain extract, wherein the liquid-phase simulated moving bed comprises the following four functional zones:
a desorption area: is positioned in the area between the desorption agent injection point and the extract liquid extraction point,
a purification area: is positioned in the area between the extraction point of the extract and the injection point of the adsorption raw material,
an adsorption zone: located in the region between the adsorption feed injection point and the raffinate withdrawal point,
a buffer area: in the region between the desorbent injection point and the raffinate withdrawal point,
the temperature of the adsorption raw material introduced into the adsorption zone is 100-230 ℃, the temperature of the desorption agent introduced into the desorption zone is 120-250 ℃, the temperature of the desorption agent introduced into the desorption zone is controlled to be 10-100 ℃ higher than the temperature of the adsorption raw material introduced into the adsorption zone, the active component of the adsorbent is selected from any one of BaX, BaKX and KY molecular sieves, and the desorption agent is 30-96 mass percent of C3～C5And 4 to 70 mass% of C7～C9A mixture of alkanes.
2. The process of claim 1 wherein the temperature of the feed to the adsorption zone is from 100 to 170 ℃ and the temperature of the desorbent to the desorption zone is from 180 to 250 ℃.
3. A process according to claim 1 or claim 2 wherein the temperature of the desorbent feed to the desorption zone is controlled to be 20 to 100 ℃ higher than the temperature of the adsorbent feed to the adsorption zone.
4. The method according to claim 1 or 2, wherein C is3～C5The fatty alcohol is n-propanol, n-butanol or n-pentanol, and the C is7～C9The alkane is n-heptane, n-octane or n-nonane.
5. The method according to claim 1 or 2, wherein the mass flow ratio of the desorbent to the adsorbent fed to the liquid-phase simulated moving bed is 3.0 to 10.
6. The process according to claim 1 or 2, wherein the space velocity of the adsorbent raw material relative to the feed volume of the adsorbent is 0.1 to 0.5h-1。
7. The method according to claim 1, wherein the adsorbent has a water content of 2.0 to 6.0% by mass as measured by burning at 600 ℃ for 2 hours.
8. The method according to claim 1, wherein the molar ratio of silica to alumina of the X molecular sieve is 2.05 to 2.95, and the molar ratio of silica to alumina of the Y molecular sieve is 4 to 7.
9. The process according to claim 1, wherein BaO and K in the BaKX molecular sieve2The molar ratio of O is 3-50: 1.
10. the method according to claim 1 or 2, characterized in that the desorbent contains 20 to 120ppm of water.
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Cited By (2)
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| CN113731352A (en) * | 2021-06-23 | 2021-12-03 | 浙江环化科技有限公司 | Adsorbent and method for adsorbing and separating m-cresol and p-cresol by using same |
| CN116239451A (en) * | 2022-12-16 | 2023-06-09 | 中触媒新材料股份有限公司 | Separation and purification method of m-cresol |
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| CN113731352A (en) * | 2021-06-23 | 2021-12-03 | 浙江环化科技有限公司 | Adsorbent and method for adsorbing and separating m-cresol and p-cresol by using same |
| CN116239451A (en) * | 2022-12-16 | 2023-06-09 | 中触媒新材料股份有限公司 | Separation and purification method of m-cresol |
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