Method for deeply removing tar and sulfur-containing impurities from resorcinol hydrolysate

Abstract

The invention discloses a method for deeply removing tar and sulfur-containing impurities from resorcinol hydrolysate, and in particular relates to a method for removing byproduct tar in the hydrolysate obtained by catalyzing m-phenylenediamine serving as a raw material with a strong acid solution before the product resorcinol is extracted, and further removing the sulfur-containing impurities from the extracted rich oil phase. The method mainly comprises the following steps: carrying out three-stage tempering and decoking, namely adding alkali to a hydrolysis stock solution for tempering by utilizing the characteristic that the phase-like characteristic of tar is obviously changed along with the change of an environmental acid value, and then obtaining decoking filtrate by virtue of the adsorption and filtration-aiding action of powdered activated carbon; multi-stage countercurrent decolorization: carrying out countercurrent adsorption deep purification by adopting powdered activated carbon, directly entering the obtained decolorized hydrolysate into a subsequent continuous extraction process, and intercepting the powdered activated carbon for front-end desulfurization and tempering decoking; and adding a desulfurizing agent into the extracted rich oil phase to deeply remove sulfur-containing impurities. According to the method, the removal rate of tar and sulfur-containing impurities in the hydrolyzed material is high, the follow-up extraction operation is not forced to be stopped periodically due to interference of tar, the extracted rich oil phase does not need to stay on line in a large volume to wait for tar layering and manual decoking, and the sulfur element index in the final product can be remarkably reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical mass transfer and separation, and in particular relates to a method for separating by-product tar and sulfur-containing impurities from resorcinol hydrolyzate. Background Art

[0002] The technical route of using sulfuric acid to catalyze the hydrolysis of m-phenylenediamine in the production of resorcinol has been widely accepted. The hydrolyzate uses a weak polar extractant to separate resorcinol, and then enters the tower to purify the product. The above hydrolyzate contains a high concentration of by-product impurities, mainly small and medium molecular weight tars, with a content of usually 600-6000ppm. These by-product impurity components will cause great interference to the production operation during the extraction and tower separation process. In addition, some sulfur-containing compounds derived from sulfuric acid can enter the final distillation product in trace amounts, making the sulfur content of the product reach 70-150ppm or higher.

[0003] The serious impact of tar and other impurities on production operations and product quality is specifically manifested in two aspects: first, when the extractant is added during the extraction operation and mixed with the mass transfer, a large volume of oil-water intermediate phase that is easy to adhere to the wall will be formed. The volume of the intermediate phase in this field is more than ten times higher than that in other extraction occasions. In the countercurrent extraction device, the high-concentration part of the intermediate phase will adhere to the wall to form the so-called tar phase. After the tar phase is enriched, it can not only quickly block the internal structure and pipe openings of the extraction equipment, but also become a slow-release source of the tar phase; and the low-concentration part of the intermediate phase and the slow-release tar phase are carried along with the oil and water phases downstream, forcing the number of extraction stages to increase. The purity of the oil and water phase output at the last stage of the countercurrent is greatly reduced, resulting in the production line having to frequently clean the extraction device online or shut down for cleaning. Secondly, considerable tar components enter the oil-rich phase after extraction. Small molecular tar is dissolved, but more of it is still in the intermediate phase and carries sulfur-containing electrolyte emulsion, and then enters the subsequent tower section with the oil-rich phase, resulting in reduced purity of the material entering the tower and excessive sulfur content in the final product.

[0004] For this reason, it is necessary to cache the oil-rich phase after extraction online for a long time in production, wait for the intermediate phase to settle and stratify after stabilization, and then manually clean and discharge the tar phase. However, this operation method will greatly increase the volume of the online extractant, increase the VOC unorganized emissions and safety hazards. In addition, in the process of cleaning the tar phase in the above extraction section, it will also cause considerable losses of the extractant and resorcinol product. At present, production units in this field are trying to solve the various drawbacks caused by the above-mentioned tar and other impurities, but the separation effect is not ideal, especially the volume of the above-mentioned intermediate phase in the extraction cannot be effectively reduced.

[0005] For example, the method for removing tar from resorcinol hydrolyzate disclosed in the prior art "A device and method for removing tar from m-phenylenediamine acidic hydrolyzate (CN114539031A)" includes the following steps: the acidic hydrolyzate is subjected to sedimentation and plate-frame filter pressing to remove a small amount of tar, and then the tar in the acidic hydrolyzate is intercepted again by a ceramic ultrafiltration membrane. In fact, the molecular weight distribution of dissolved tar in the hydrolyzate is generally 1kD to 300kD, and the molecular weight cutoff of the ceramic membrane with an accuracy of 30nm for long-chain molecules is generally more than hundreds of thousands, so the tar components in the benzene field cannot be effectively intercepted.

[0006] For example, the prior art "A method for preparing resorcinol by hydrolysis of m-phenylenediamine (CN 104529712B)" discloses that the resorcinol hydrolyzate is concentrated by three-stage flash evaporation, then removed from the tar by an activated carbon adsorption device, and then extracted with an extractant by countercurrent through an extraction tower to obtain a water phase and an oil phase. The tar separation is simply based on the adsorption of activated carbon, and the extracted oil phase is then de-esterified, distilled, and the like to obtain the resorcinol product. It was found that the concentration of activated carbon used must exceed 3% or even 5% to effectively alleviate the interference of the intermediate phase, and at this time, the product concentration in the hydrolyzate is reduced. This is mainly because tar will wrap the activated carbon particles to saturate their surface, and a large amount of adsorption pore volume cannot be utilized, and the resorcinol product with a smaller molecular weight than tar will also be adsorbed by the activated carbon (resorcinol can reach hundreds of milligrams / gram of carbon adsorption loss). Therefore, unilaterally increasing the amount of activated carbon not only increases production costs, but also leads to significant product losses.

[0007] In addition, there are few reports on methods for efficiently removing tar and sulfur-containing components before and after hydrolyzate extraction in this field. The simple use of activated carbon adsorption has the disadvantages of large activated carbon consumption and large product losses discharged with the activated carbon wet filter cake, which is not economical. Summary of the invention

[0008] Purpose of the invention: The technical problem to be solved by the present invention is how to efficiently and deeply remove impurities such as by-product tar in the hydrolyzate of resorcinol, improve the production efficiency of the extraction process, reduce the sulfur content of the final product, and reduce the loss of the product and the extractant.

[0009] Technical solution: The method for deeply removing tar and sulfur-containing impurities from resorcinol hydrolyzate of the present invention is obtained by catalytic hydrolysis of m-phenylenediamine with sulfuric acid solution. The deep removal method comprises the following steps:

[0010] (1) Three-stage conditioning and decoking: The hydrolyzed resorcinol solution with an initial acidity of pH < 0 is neutralized and conditioned with ammonia to achieve three-stage conditioning from high to low acidity. A phase separator is connected in series at each stage to eliminate tar emulsification. The pH value after the final conditioning is 2 to 6.5. Then, with the help of filter interception using powdered activated carbon, a plate and frame filter press is used to obtain a tar carbon filter cake and a decoking filtrate.

[0011] (2) Multi-stage countercurrent adsorption: A flocculant is added to the decoking filtrate, and then the colored impurities in the material are deeply removed by powdered activated carbon through multi-stage countercurrent adsorption. The activated carbon separation of each adsorption stage forms an activated carbon concentrated slurry and an adsorption clear liquid. The final adsorption clear liquid is subjected to additional security precision filtration to completely intercept the activated carbon to obtain a decolorized hydrolyzate. The activated carbon of the primary adsorption is separated by blind-end filtration. The intercepted activated carbon is continuously sent to step (1) in the form of a slurry in the countercurrent to be used as a filter aid for separating tar.

[0012] (3) Desulfurization of the rich oil phase: The hydrolyzate after multi-stage countercurrent adsorption decolorization is subjected to countercurrent extraction to obtain a resorcinol-rich extracted oil phase, a desulfurizer is added to the extracted oil phase and mixed thoroughly, and then the raffinate and the intermediate phase droplets are intercepted by hydrophobic filtration to obtain a clear and transparent purified rich oil phase, which is then sent to the tower separation section.

[0013] The present invention fully takes into account the process environment of actual production, and sequentially subjects the hydrolyzate to multi-stage conditioning by liquid ammonia, multi-stage countercurrent adsorption by powdered activated carbon after adding a flocculant, desulfurization of the oil-rich phase after extraction with a chemical, and then interception of the emulsified water phase oil-water intermediate phase, which can ensure smooth and efficient extraction units and greatly reduce the sulfur content of the final product.

[0014] Specifically, step (1) utilizes the characteristics of tar being supersaturated in the hydrolyzate and separating into phases under appropriate acid value, firstly adds alkali to condition, and then eliminates tar emulsification through a phase separator, with a total of three stages of alkali conditioning and phase separation. The optimal parameters of each acid value are determined by comprehensively considering the tar molecular weight distribution, filtration efficiency and product loss in the filter cake, and then the plate and frame filter press is used to obtain the tar carbon filter cake and the decoking filtrate by using the filter aid effect of the applied powdered carbon. The decoking filtrate still contains some tar and other impurities that affect the smooth operation of the extraction unit.

[0015] In step (2), flocculants are added to the decoking filtrate to promote the phase separation of impurities, and then a low-cost and high-efficiency powdered activated carbon countercurrent adsorption method is used to deeply remove small molecular tar components. The activated carbon suspension that has completed adsorption at each stage is separated and retained by the activated carbon online continuously, and the decolorized filtrate and concentrated slurry are continuously flowed on site. The concentrated slurry is returned to the previous stage and finally to the primary adsorption, while the decolorized filtrate is discharged to the next stage until the final adsorption; the final adsorption clear liquid is filtered through the security fine filter to obtain the decolorized hydrolyzate, and then sent to the subsequent extraction process after buffering adjustment; and the activated carbon retained by the security fine filter is directly returned to the front end of a certain level of adsorption. All activated carbons are countercurrently passed through the primary adsorption, and the primary adsorption separation set of carbon adopts blind-end filtration to force the powdered carbon to form a filter cake, and the filter cake is periodically blown off and reset to maintain the filtration speed. Each time the filter cake is reset and formed, the decolorized filtrate is discharged to the secondary adsorption; the blown filter cake is discharged in the form of slurry to the filter aid for intercepting tar and forming the filter cake in step (1). The decolorized hydrolyzate is subjected to countercurrent extraction to form a raffinate water phase and an oil-rich phase.

[0016] Step (3) adds an appropriate amount of desulfurizer to the rich oil phase. After sufficient mixing and reaction, most of the sulfur-containing components will precipitate from the oil phase to form an emulsified water phase and an oil-water intermediate phase, and then a clear and transparent rich oil phase is obtained by hydrophobic filtration.

[0017] After the present invention adopts the above steps to remove most of the impurities in the resorcinol hydrolyzate, the oil-water intermediate phase in the extraction can be effectively avoided, and the sulfur-containing components in the rich oil phase can also be greatly reduced.

[0018] Preferably, in step (2) of the method of the present invention, the flocculant may be an anionic high molecular polymer, such as anionic polyacrylamide, and the dosage thereof may be 10 to 200 mg / L.

[0019] Preferably, in step (2) of the method of the present invention, the activated carbon concentration used in countercurrent adsorption is 2 to 6 g / L, and the adsorption time for each stage is 0.5 to 3 h; the primary blind-end filtration uses a metal filter material with a precision of 300 to 800 mesh and a filtration pressure difference of 0.05 to 0.25 MPa.

[0020] Preferably, in step (2) of the method of the present invention, the number of countercurrent adsorption stages is not less than 4, and all activated carbons are countercurrently subjected to primary adsorption and returned to step (1) with the primary concentrated slurry to be used as a filter aid for separating tar.

[0021] Furthermore, in step (3) of the method of the present invention, the decolorized hydrolyzate is first buffered and adjusted to a pH value of 0 to 5.5 before being sent to the extraction step.

[0022] Preferably, in step (3) of the method of the present invention, the desulfurizing agent may be sulfate of a divalent metal ion, including but not limited to ferrous sulfate, copper sulfate or zinc sulfate, with an amount of 75 to 1500 mg / L.

[0023] Beneficial effects: Compared with the prior art, the significant advantages of the present invention are: the method of deeply removing tar and sulfur-containing impurities from the hydrolyzate of resorcinol can reduce the residual tar in the decolorized hydrolyzate to below 100 mg / L, and there is no intermediate phase accumulation in the extraction section, so that it can operate stably and efficiently; the sulfur content in the final product can be reduced to 5-20 mg / L. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The process flow chart of the present invention for deeply removing tar and sulfur-containing impurities from resorcinol hydrolyzate;

[0025] Figure 2 This is a picture of the butyl acetate extraction sample after deep impurity removal of resorcinol hydrolyzate;

[0026] Figure 3This is a comparison of the extracted oil before and after deep impurity removal of resorcinol hydrolyzate.

[0027] The letters and numbers in the diagram represent the following:

[0028] 1: primary conditioning phase separation; 2: secondary conditioning phase separation; 3: tertiary conditioning phase separation; 4: plate and frame filter press; 5: primary adsorption; 6: primary solid-liquid separation; 7: final adsorption; 8: final solid-liquid separation; 9: security fine filter; 10: activated carbon batching device; 11: countercurrent extraction unit; 12: rich oil phase desulfurization device; 13: hydrophobic filter;

[0029] A: hydrolyzate; B: raffinate hydrolyzate; C: powdered activated carbon; D: tar carbon filter cake; E: flocculant; F: security fine filtration intercepted slurry; G: extractant; H: desulfurizer; I: purified rich oil phase;

[0030] a: decoking filtrate; b: primary adsorption liquid; c: primary adsorption clear liquid; d: countercurrent carbon slurry; e: final adsorption liquid; f: final adsorption clear liquid; g: decolorized hydrolyzate; h: oil-rich phase; i: emulsified oil-rich phase; DETAILED DESCRIPTION

[0031] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0032] The resorcinol hydrolyzate targeted by the present invention is obtained by catalytic hydrolysis of m-phenylenediamine with sulfuric acid solution, and contains a relatively high concentration of NH 3+ 、SO4 2- Electrolyte solutions, as well as byproduct tar, sulfur compounds and other impurities with high concentrations need to be removed. The multi-stage countercurrent adsorption stage of the present invention uses an activated carbon continuous countercurrent adsorption technology, which is a well-known technology in the field of activated carbon adsorption technology.

[0033] The method for deeply removing tar and sulfur-containing impurities from resorcinol hydrolyzate of the present invention has the following flow chart: Figure 1 As shown, the following steps are included:

[0034] (1) Three-stage conditioning and decoking: The hydrolyzate of resorcinol with an initial acidity of pH <0 is neutralized and conditioned with ammonia to adjust the acidity in three stages from high to low. A phase separator is connected in series after each stage of conditioning. The pH value of the hydrolyzate after the final stage of conditioning is 2 to 6.5. Then, with the help of filter interception using powdered activated carbon, plate and frame filter pressing is used to obtain tar carbon filter cake and decoking filtrate;

[0035] (2) Multi-stage countercurrent adsorption: A flocculant is added to the decoking filtrate, and then the colored impurities in the material are deeply removed by powdered activated carbon through multi-stage countercurrent adsorption. The activated carbon separation of each adsorption stage forms an activated carbon concentrated slurry and an adsorption clear liquid. The final adsorption clear liquid is subjected to additional security precision filtration to completely intercept the activated carbon to obtain a decolorized hydrolyzate. The activated carbon of the primary adsorption is separated by blind-end filtration.

[0036] (3) Desulfurization of the rich oil phase: The hydrolyzate after multi-stage countercurrent adsorption decolorization is subjected to countercurrent extraction to obtain an extracted oil phase rich in resorcinol. A desulfurizer is added to the extracted oil phase and mixed thoroughly. The water phase and the oil-water intermediate phase droplets are then intercepted by hydrophobic filtration to obtain a clear and transparent purified rich oil phase, which is then sent to the tower separation section.

[0037] Example 1

[0038] The acid value of the hydrolyzate of the feed in Example 1 is 6.5% in terms of sulfuric acid, and the tar content is about 950 mg / L. The method for deep removal of tar and sulfur-containing impurities comprises the following steps:

[0039] (1) The incoming hydrolyzate is conditioned with liquid ammonia in three stages and connected in series with a phase separator. The pH is adjusted to 1, 1.5 and 3.5 respectively. Activated carbon is then applied to intercept the precipitated tar by plate and frame filter pressing to obtain a decoking filtrate with a tar content of less than 320 mg / L.

[0040] (2) 140 mg / L of anionic polyacrylamide is added to the decoking filtrate and mixed, and then the hydrolyzate is deeply purified by four-stage countercurrent adsorption of powdered activated carbon in series. The activated carbon concentration is 2.5 g / L, and the adsorption time of each stage is 2 h. The primary adsorption liquid is separated from the activated carbon by blind-end filtration using a metal filter material with a precision of 400 mesh, and the filtration pressure is 0.1-0.2 MPa. The fourth-stage adsorption clear liquid is filtered through a membrane security filter to remove carbon, and then buffered and adjusted before entering the countercurrent extraction process. The tar content is less than 90 mg / L; all the activated carbon is returned to the conditioning and decoking unit with the primary concentrated slurry.

[0041] (3) The decolorized hydrolyzate is subjected to countercurrent extraction to separate resorcinol to obtain an oil-rich phase. Ferrous sulfate is first added to the oil phase in an amount of 800 mg / L. After being fully homogenized and mixed, it is filtered through a hydrophobic membrane to obtain a clear and transparent purified oil-rich phase.

[0042] The hydrolyzate obtained in Example 1 of the present invention was extracted with butyl acetate at different acid values. No obvious intermediate phase was precipitated, and the two phases were clear, which proved that the impurities were effectively removed. Figure 2 As shown. And the decolorized hydrolyzate was compared with the ordinary filtered hydrolyzate, and butyl acetate was added for extraction. The effect was significantly different, as shown in Figure 3As shown, it is verified that the method can effectively remove tar from the hydrolyzate of resorcinol.

[0043] Example 2

[0044] The acid value of the incoming hydrolyzate of Example 2 is 9% in terms of sulfuric acid, and the tar content is about 5200 mg / L. The method for deeply removing tar and sulfur-containing impurities comprises the following steps:

[0045] (1) The incoming hydrolyzate is conditioned with liquid ammonia in three stages and connected in series with a phase separator. The pH is adjusted to 0.5, 2 and 5.5 respectively. Activated carbon is then used to intercept the tar precipitated from the conditioning by plate and frame filter pressing to obtain a decoking filtrate with a tar content of less than 650 mg / L.

[0046] (2) 85 mg / L of anionic polyacrylamide was added to the decoking filtrate and mixed, and then four-stage powdered activated carbon countercurrent adsorption was connected in series to deeply purify the hydrolyzate. The activated carbon concentration was 4.5 g / L, and the adsorption time of each stage was 1.5 h. The primary adsorption liquid was separated from the activated carbon by blind-end filtration using a filter material with a precision of 500 mesh, and the filtration pressure was 0.25 MPa. The fourth-stage adsorption clear liquid was filtered through a membrane security filter to remove carbon, and then buffered and adjusted before entering the countercurrent extraction process. The tar content was less than 90 mg / L; all the activated carbon was returned to the conditioning and decoking unit with the primary concentrated slurry.

[0047] (3) The decolorized hydrolyzate is subjected to countercurrent extraction to separate resorcinol to obtain an oil-rich phase. Zinc sulfate is first added to the oil phase in an amount of 1250 mg / L. After sufficient homogeneous mixing, it is filtered through a hydrophobic membrane to obtain a clear and transparent purified oil-rich phase.

[0048] Example 3

[0049] The acid value of the incoming hydrolyzate of Example 3 is 7.5% in terms of sulfuric acid, and the tar content is about 2300 mg / L. The method for deeply removing tar and sulfur-containing impurities comprises the following steps:

[0050] (1) The incoming hydrolyzate is conditioned with liquid ammonia in three stages and connected in series with a phase separator, and the pH is adjusted to 0.5, 3 and 6.5 in sequence, and then activated carbon is applied to intercept the tar precipitated by conditioning by plate and frame filter pressing to obtain a decoking filtrate with a tar content of less than 650 mg / L;

[0051] (2) 100 mg / L of anionic polyacrylamide is added to the decoking filtrate and mixed, and then four-stage powdered activated carbon is connected in series for countercurrent adsorption to deeply purify the hydrolyzate. The activated carbon concentration is 3.5 g / L, and the adsorption time of each stage is 1.33 h. The primary adsorption liquid is separated from the activated carbon by blind-end filtration using a filter material with a precision of 600 mesh, and the filtration pressure is 0.2 MPa. The fourth-stage adsorption clear liquid is filtered through a membrane security filter to remove carbon, and then buffered and adjusted before entering the countercurrent extraction process. The tar content is less than 120 mg / L; all the activated carbon is returned to the conditioning and decoking unit with the primary concentrated slurry for application;

[0052] (3) The decolorized hydrolyzate is subjected to countercurrent extraction to separate resorcinol to obtain an oil-rich phase. Copper sulfate is first added to the oil phase in an amount of 550 mg / L. After being fully homogenized and mixed, it is filtered through a hydrophobic membrane to obtain a clear and transparent purified oil-rich phase.

[0053] The tar content in each treatment stage in the above Example 1 and Example 3 of the present invention was tested, and the obtained results are shown in the following Table 1.

[0054] Table 1 Tar content of resorcinol hydrolyzate at each treatment stage in Example 1 and Example 3

[0055]

Claims

1. A method for deeply removing tar and sulfur-containing impurities from a resorcinol hydrolyzate, wherein the resorcinol hydrolyzate is obtained by catalytic hydrolysis of m-phenylenediamine with a sulfuric acid solution, characterized in that: The deep removal method comprises the following steps: (1) Three-stage conditioning and decoking: The hydrolyzate of resorcinol with an initial acidity of pH <0 is neutralized and conditioned with ammonia to adjust the acidity in three stages from high to low. A phase separator is connected in series after each stage of conditioning. The pH value of the hydrolyzate after the final stage of conditioning is 2 to 6.

5. Then, with the help of filter interception using powdered activated carbon, plate and frame filter pressing is used to obtain tar carbon filter cake and decoking filtrate; (2) Multi-stage countercurrent adsorption: A flocculant is added to the decoking filtrate, and then the colored impurities in the material are deeply removed by multi-stage countercurrent adsorption using powdered activated carbon. The activated carbon separation at each adsorption stage forms an activated carbon concentrated slurry and an adsorption clear liquid. The final adsorption clear liquid is subjected to additional security precision filtration to completely intercept the activated carbon to obtain a decolorized hydrolyzate. The activated carbon of the primary adsorption is separated by blind-end filtration. (3) Desulfurization of the rich oil phase: The hydrolyzate after multi-stage countercurrent adsorption decolorization is subjected to countercurrent extraction to obtain an extracted oil phase rich in resorcinol. A desulfurizer is added to the extracted oil phase and mixed thoroughly. The water phase and the oil-water intermediate phase droplets are then intercepted by hydrophobic filtration to obtain a clear and transparent purified rich oil phase, which is then sent to the tower separation section.

2. The method for deep removal of tar and sulfur-containing impurities from resorcinol hydrolyzate according to claim 1, characterized in that: In step (2), the flocculant is an anionic high molecular polymer, and its dosage is 10 to 200 mg / L.

3. The method for deep removal of tar and sulfur-containing impurities from resorcinol hydrolyzate according to claim 1, characterized in that: In step (2), the activated carbon concentration used in the countercurrent adsorption is 2-6 g / L, and the adsorption time of each stage is 0.5-3 h; the primary blind-end filtration uses a metal filter material with a precision of 300-800 mesh and a filtration pressure difference of 0.05-0.25 MPa.

4. The method for deep removal of tar and sulfur-containing impurities from resorcinol hydrolyzate according to claim 1, characterized in that: In step (2), the countercurrent adsorption stage is not less than 4, and all activated carbon undergoes primary adsorption in countercurrent and returns to step (1) with the primary concentrated slurry to be used as a filter aid for separating tar.

5. The method for deep removal of tar and sulfur-containing impurities from resorcinol hydrolyzate according to claim 1, characterized in that: In step (3), the decolorized hydrolyzate is first buffered and adjusted to a pH value of 0 to 5.5 before being sent to the extraction process.

6. The method for deep removal of tar and sulfur-containing impurities from resorcinol hydrolyzate according to claim 1, characterized in that: In step (3), the desulfurizing agent is a divalent metal sulfate, and the dosage is 75 to 1500 mg / L.

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