CN-122010868-A - Method for refining crude MBT by solvent method tubular sectional baffling continuous extraction

Abstract

The invention belongs to the technical field of rubber accelerator production, and particularly relates to a solvent method tubular sectional baffling continuous extraction refining method for crude MBT. The high pressure product is overflowed into solvent pipeline to make efficient extraction in turbulent flow area, the extracted liquid is static saw-tooth crystallized under positive nitrogen pressure, and the crystal is attached to saw-tooth blades regularly to grow, and finally the product is obtained through continuous filtering and sectional washing in belt filter. The invention strengthens the circulation of mixing and clarification by utilizing a tubular baffling structure, improves the mass transfer efficiency, simultaneously combines positive pressure crystallization of nitrogen, isolates oxygen and water vapor, ensures that MBT crystals have a needle-shaped structure, has large particle size and high purity, and solves the problems of low intermittent production efficiency and unstable product quality of the traditional solvent method.

Inventors

• ZHANG HUAIMENG
• ZHAO LIANJUN
• ZHANG SONG
• ZHU ZHONGWEI
• XUE XIANGJU
• ZHU GUOXU
• LIU BIN
• LIU YANG
• YANG CHUNXIA
• Guo Yansuo

Assignees

• 山东尚舜化工有限公司

Dates

Publication Date

20260512

Application Date

20260202

Claims (7)

1. 1. A solvent method tubular sectional baffling continuous extraction refining method for crude MBT is characterized by comprising the following steps: (1) Continuously feeding the crude MBT high-pressure product and an extraction solvent into a tubular extraction device, wherein the crude MBT high-pressure product enters the tubular extraction device in sections at different pipe sections, the extraction solvent flows in a baffling way in the tubular extraction device, and tubular sectional baffling continuous extraction is carried out after the crude MBT high-pressure product and the extraction solvent are mixed; (2) The extracted mixed solution enters a crystallization kettle, and static sawtooth crystallization is carried out under the positive pressure of nitrogen to obtain MBT crystal slurry; (3) And carrying out solid-liquid separation, washing and drying on the MBT crystal slurry to obtain a finished product MBT.
2. 2. The method for continuous extraction and refining of crude MBT by solvent-process tube-type staged-baffling according to claim 1, wherein the extraction solvent in step (1) is at least one of toluene, o-xylene, m-xylene, 1,2, 4-trimethylbenzene, 1,2, 4-trichlorobenzene, p-xylene, carbon disulfide or tetrachloroethylene.
3. 3. The method for refining crude MBT by solvent tube type segmented baffle continuous extraction according to claim 1, wherein the mass ratio of the total mass of the crude MBT high-pressure product to the extraction solvent in the step (1) is (0.2-4): 2, the crude MBT high-pressure product enters at the inlet A, the inlet B and the inlet C of the tube type extraction device in a segmented manner, and the mass ratio of the inlet A, the inlet B and the inlet C enters is (2-6): 1-5): 1-4.
4. 4. The method for refining crude MBT by solvent process tubular staged-baffled continuous extraction according to claim 1, wherein the temperature of tubular staged-baffled continuous extraction in step (1) is 80-115 ℃ and the extraction time is 10-100min.
5. 5. The method for continuously extracting and refining crude MBT by solvent method tubular segmented baffling is characterized in that a serrated stirring blade is arranged in a crystallization kettle in the step (2), the positive pressure of nitrogen is 0.2-1MPa in the static serrated crystallization process, the crystallization temperature is 40-80 ℃, and the cooling rate of a mixed material in the crystallization process is 0.2-3 ℃ per minute.
6. 6. The method for refining crude MBT by solvent method tubular segment baffling continuous extraction according to claim 1, wherein in the step (3), a belt filter is adopted in the solid-liquid separation and washing process, baffling continuous filtration and segment leaching operation are adopted in the solid-liquid separation and washing process, the weight ratio of fresh solvent to MBT in the segment leaching process is (0.1-2): 1, and the leaching temperature is 30-80 ℃.
7. 7. The method for refining crude MBT by solvent method tubular staged baffling continuous extraction according to claim 6, wherein the staged leaching comprises a primary washing and a secondary washing, wherein the volume of fresh solvent adopted by the primary washing accounts for 40-80% of the volume of the total washing solvent, and the volume of fresh solvent adopted by the secondary washing accounts for 20-70% of the volume of the total washing solvent.

Description

Method for refining crude MBT by solvent method tubular sectional baffling continuous extraction Technical Field The invention belongs to the technical field of rubber accelerator production, and particularly relates to a solvent method tubular sectional baffling continuous extraction refining method for crude MBT. Background The rubber vulcanization accelerator 2-mercaptobenzothiazole (MBT, CAS number: 149-30-4) is a general accelerator and is widely applied to the production of rubber products such as tires, adhesive tapes and the like. Currently, the methods for refining crude MBT mainly include acid-base and solvent methods. The acid-base method is relatively mature in process, but a large amount of high-salt wastewater is generated in the acid-base change process, and tar-like macromolecular resin is contained in waste residues, so that the environmental protection pressure is high, and the treatment cost is high. The existing solvent method avoids the problem of waste water, belongs to an environment-friendly process, but batch production is adopted at present. Batch production requires a large amount of extraction treatment processes, multiple crystallization kettles are needed, the occupied area is large, and the labor cost is high. More importantly, batch-to-batch quality fluctuation is large, the primary melting point and purity of MBT are unstable, irregular spherical crystals are often obtained in the crystallization process under normal pressure, the particle size is small, and the impurities are more wrapped, so that the method is unfavorable for subsequent washing and purification. Currently, no MBT refining method capable of realizing continuous production, improving mass transfer efficiency and stably obtaining high-purity crystals is reported in the industry. Disclosure of Invention The invention provides a method for refining crude MBT by solvent method tubular sectional baffling continuous extraction, aiming at the problems of low intermittent production efficiency and unstable product quality in the traditional MBT refining process. In order to achieve the above purpose, the invention is realized by adopting the following technical scheme: A method for continuously extracting and refining crude MBT by solvent method tubular segment baffling comprises (1) continuously feeding crude MBT high-pressure product and extraction solvent into tubular extraction device, wherein the crude MBT high-pressure product enters in segments at different tube sections of the tubular extraction device, a plurality of baffles distributed in staggered manner are arranged in the solvent tube, the extraction solvent flows in the tubular extraction device in baffling manner, and tubular segment baffling continuous extraction is carried out after the crude MBT high-pressure product and the extraction solvent are mixed. (2) And (3) the extracted mixed solution enters a crystallization kettle, and static sawtooth crystallization is carried out under the positive pressure of nitrogen, so that MBT crystal slurry is obtained. (3) And carrying out solid-liquid separation, washing and drying on the MBT crystal slurry to obtain a finished product MBT. Preferably, in the step (1), the extraction solvent is at least one of toluene, o-xylene, m-xylene, 1,2, 4-trimethylbenzene, 1,2, 4-trichlorobenzene, p-xylene, carbon disulfide, and tetrachloroethylene, and toluene is preferably used. Preferably, the ratio of the total mass of the crude MBT high-pressure product to the extraction solvent in step (1) is (0.2-4): 2, and the weight ratio of the high-pressure product to the toluene mixed solution is preferably (0.5-1.5): 2. The crude MBT high pressure product enters at the inlet A, the inlet B and the inlet C of the tubular extraction device in a separation mode, and the mass ratio of the inlet A, the inlet B and the inlet C is (2-6): 1-5): 1-4. Preferably, in the step (1), the temperature of the tubular sectional baffled continuous extraction is 80-115 ℃, preferably 100-110 ℃, and the extraction time is 10-100min, preferably 30-50min. Preferably, in the step (2), a serrated stirring blade is arranged in the crystallization kettle, the positive pressure of nitrogen is 0.2-1MPa, preferably 0.4-0.6MPa, the crystallization temperature is 40-80 ℃, preferably 50-70 ℃, and the cooling rate is 0.2-3 ℃, preferably (0.5-2) °c/min in the static serrated crystallization process. Preferably, in step (3), the solid-liquid separation and washing, i.e., solvent separation and stage leaching, are performed in a belt filter, including baffled continuous filtration and stage leaching, with a weight ratio of fresh solvent to MBT for washing of (0.1-2): 1, preferably (0.1-1), and a washing temperature of 30-80 ℃, preferably 50-70 ℃. In step (2), the staged washing comprises a primary washing and a secondary washing, wherein the fresh solvent of the primary washing is 40-80% (V/V), preferably 30-50% of the total washing, and the fresh solvent of th