CN114853590A - Novel polyformaldehyde depolymerization method - Google Patents
Novel polyformaldehyde depolymerization method Download PDFInfo
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- CN114853590A CN114853590A CN202210434808.5A CN202210434808A CN114853590A CN 114853590 A CN114853590 A CN 114853590A CN 202210434808 A CN202210434808 A CN 202210434808A CN 114853590 A CN114853590 A CN 114853590A
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- 229920006324 polyoxymethylene Polymers 0.000 title claims abstract description 78
- 238000000034 method Methods 0.000 title claims abstract description 28
- WSFSSNUMVMOOMR-UHFFFAOYSA-N Formaldehyde Chemical compound O=C WSFSSNUMVMOOMR-UHFFFAOYSA-N 0.000 claims abstract description 177
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims abstract description 31
- 239000003054 catalyst Substances 0.000 claims abstract description 31
- 238000006243 chemical reaction Methods 0.000 claims abstract description 31
- 239000007788 liquid Substances 0.000 claims abstract description 22
- 239000011259 mixed solution Substances 0.000 claims abstract description 14
- 238000002156 mixing Methods 0.000 claims abstract description 13
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 11
- 239000000203 mixture Substances 0.000 claims abstract description 9
- 239000000463 material Substances 0.000 claims abstract description 8
- 238000005086 pumping Methods 0.000 claims abstract description 8
- ROSDSFDQCJNGOL-UHFFFAOYSA-N Dimethylamine Chemical compound CNC ROSDSFDQCJNGOL-UHFFFAOYSA-N 0.000 claims description 27
- LRHPLDYGYMQRHN-UHFFFAOYSA-N N-Butanol Chemical compound CCCCO LRHPLDYGYMQRHN-UHFFFAOYSA-N 0.000 claims description 20
- -1 polyoxymethylene Polymers 0.000 claims description 19
- 230000008569 process Effects 0.000 claims description 14
- 229930040373 Paraformaldehyde Natural products 0.000 claims description 12
- ZMANZCXQSJIPKH-UHFFFAOYSA-N Triethylamine Chemical compound CCN(CC)CC ZMANZCXQSJIPKH-UHFFFAOYSA-N 0.000 claims description 12
- BTANRVKWQNVYAZ-UHFFFAOYSA-N butan-2-ol Chemical compound CCC(C)O BTANRVKWQNVYAZ-UHFFFAOYSA-N 0.000 claims description 11
- HPNMFZURTQLUMO-UHFFFAOYSA-N diethylamine Chemical compound CCNCC HPNMFZURTQLUMO-UHFFFAOYSA-N 0.000 claims description 11
- 150000003138 primary alcohols Chemical class 0.000 claims description 11
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 claims description 10
- 150000003333 secondary alcohols Chemical class 0.000 claims description 10
- ZXEKIIBDNHEJCQ-UHFFFAOYSA-N isobutanol Chemical compound CC(C)CO ZXEKIIBDNHEJCQ-UHFFFAOYSA-N 0.000 claims description 8
- KPSSIOMAKSHJJG-UHFFFAOYSA-N neopentyl alcohol Chemical compound CC(C)(C)CO KPSSIOMAKSHJJG-UHFFFAOYSA-N 0.000 claims description 8
- 150000001875 compounds Chemical class 0.000 claims description 5
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical group [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 4
- 229940035429 isobutyl alcohol Drugs 0.000 claims description 3
- GSEJCLTVZPLZKY-UHFFFAOYSA-N Triethanolamine Chemical compound OCCN(CCO)CCO GSEJCLTVZPLZKY-UHFFFAOYSA-N 0.000 claims description 2
- HPXRVTGHNJAIIH-UHFFFAOYSA-N cyclohexanol Chemical compound OC1CCCCC1 HPXRVTGHNJAIIH-UHFFFAOYSA-N 0.000 claims description 2
- 230000035484 reaction time Effects 0.000 claims description 2
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 2
- 239000008098 formaldehyde solution Substances 0.000 abstract description 12
- 239000000126 substance Substances 0.000 abstract description 8
- 239000002994 raw material Substances 0.000 abstract description 5
- 239000002699 waste material Substances 0.000 abstract description 5
- 230000008901 benefit Effects 0.000 abstract description 4
- 235000019256 formaldehyde Nutrition 0.000 description 52
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 30
- 239000000243 solution Substances 0.000 description 20
- 239000000047 product Substances 0.000 description 14
- 238000003860 storage Methods 0.000 description 14
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 12
- 230000000052 comparative effect Effects 0.000 description 8
- 238000012691 depolymerization reaction Methods 0.000 description 7
- GEHJYWRUCIMESM-UHFFFAOYSA-L sodium sulfite Chemical compound [Na+].[Na+].[O-]S([O-])=O GEHJYWRUCIMESM-UHFFFAOYSA-L 0.000 description 7
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 6
- 238000013329 compounding Methods 0.000 description 6
- 238000004519 manufacturing process Methods 0.000 description 6
- 238000006116 polymerization reaction Methods 0.000 description 6
- 239000000523 sample Substances 0.000 description 6
- 238000004448 titration Methods 0.000 description 6
- 230000015572 biosynthetic process Effects 0.000 description 4
- 238000007086 side reaction Methods 0.000 description 4
- 239000002904 solvent Substances 0.000 description 4
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 3
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 3
- LDKDGDIWEUUXSH-UHFFFAOYSA-N Thymophthalein Chemical compound C1=C(O)C(C(C)C)=CC(C2(C3=CC=CC=C3C(=O)O2)C=2C(=CC(O)=C(C(C)C)C=2)C)=C1C LDKDGDIWEUUXSH-UHFFFAOYSA-N 0.000 description 3
- 125000002147 dimethylamino group Chemical group [H]C([H])([H])N(*)C([H])([H])[H] 0.000 description 3
- 239000012535 impurity Substances 0.000 description 3
- 239000002808 molecular sieve Substances 0.000 description 3
- 239000000741 silica gel Substances 0.000 description 3
- 229910002027 silica gel Inorganic materials 0.000 description 3
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 description 3
- 229940001482 sodium sulfite Drugs 0.000 description 3
- 235000010265 sodium sulphite Nutrition 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 239000003153 chemical reaction reagent Substances 0.000 description 2
- XBDQKXXYIPTUBI-UHFFFAOYSA-N dimethylselenoniopropionate Natural products CCC(O)=O XBDQKXXYIPTUBI-UHFFFAOYSA-N 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 2
- 230000014759 maintenance of location Effects 0.000 description 2
- 239000000178 monomer Substances 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 239000011734 sodium Substances 0.000 description 2
- 239000011343 solid material Substances 0.000 description 2
- 238000005303 weighing Methods 0.000 description 2
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 description 1
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 1
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 1
- CERQOIWHTDAKMF-UHFFFAOYSA-N Methacrylic acid Chemical compound CC(=C)C(O)=O CERQOIWHTDAKMF-UHFFFAOYSA-N 0.000 description 1
- 239000002250 absorbent Substances 0.000 description 1
- 230000002745 absorbent Effects 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 150000001299 aldehydes Chemical class 0.000 description 1
- 229940101006 anhydrous sodium sulfite Drugs 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 238000004821 distillation Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 239000000499 gel Substances 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 1
- 239000003112 inhibitor Substances 0.000 description 1
- 239000000543 intermediate Substances 0.000 description 1
- 238000010813 internal standard method Methods 0.000 description 1
- 239000006101 laboratory sample Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 229940087646 methanolamine Drugs 0.000 description 1
- WSFSSNUMVMOOMR-NJFSPNSNSA-N methanone Chemical compound O=[14CH2] WSFSSNUMVMOOMR-NJFSPNSNSA-N 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 235000019260 propionic acid Nutrition 0.000 description 1
- IUVKMZGDUIUOCP-BTNSXGMBSA-N quinbolone Chemical compound O([C@H]1CC[C@H]2[C@H]3[C@@H]([C@]4(C=CC(=O)C=C4CC3)C)CC[C@@]21C)C1=CCCC1 IUVKMZGDUIUOCP-BTNSXGMBSA-N 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 238000011410 subtraction method Methods 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
- C07C45/51—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by pyrolysis, rearrangement or decomposition
- C07C45/55—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by pyrolysis, rearrangement or decomposition of oligo- or polymeric oxo-compounds
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J31/00—Catalysts comprising hydrides, coordination complexes or organic compounds
- B01J31/02—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides
- B01J31/0234—Nitrogen-, phosphorus-, arsenic- or antimony-containing compounds
- B01J31/0235—Nitrogen containing compounds
- B01J31/0237—Amines
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/62—Plastics recycling; Rubber recycling
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Catalysts (AREA)
Abstract
The invention discloses a novel polyformaldehyde depolymerization method, which comprises the following steps: step 1), introducing hot steam or hot water, a mixed solution of monohydric alcohol and a catalyst into polyformaldehyde, then uniformly mixing and preheating, and reacting to obtain a mixed material; the mass ratio of the mixed liquid of polyformaldehyde and monohydric alcohol to the catalyst is 1: (2-3): (0.03-0.05); and 2), pumping the mixture into a reactor for reaction, keeping the reaction temperature at 70-80 ℃, and finishing the reaction for 15-25 s to obtain depolymerization liquid with the formaldehyde content of 36.9%. The formaldehyde solution obtained by depolymerizing polyformaldehyde by the method can be used as a raw material of some chemical products, and the content of the obtained formaldehyde solution is higher than the national standard of qualified products (more than 36.5%) of industrial formaldehyde solution, so that the aims of turning harm into benefit and changing waste into valuable are fulfilled.
Description
Technical Field
The invention relates to the field of formaldehyde preparation and storage, in particular to a novel polyformaldehyde depolymerization method.
Background
Formaldehyde (HCHO) is active in chemical property and strong in reaction capacity, and can react with acetic acid, propionic acid and the like to generate important chemical intermediates such as acrylic acid, methacrylic acid and the like. The polyformaldehyde HO (CH2O) nH is a product formed by dehydrating and polycondensing an aqueous formaldehyde solution, and is mainly divided into two types, namely low-polymerization-degree polyformaldehyde (the polymerization degree n is 2-8) and polyformaldehyde (the polymerization degree n is 8-100). Polyformaldehyde is solid powder, is convenient to store and transport, is widely applied to chemical synthesis in chemical industry, pharmacy and other industrial fields and is an ideal substitute of industrial formaldehyde. However, polyoxymethylene itself is chemically inactive and can only be used for the reaction by depolymerizing polyoxymethylene to the monomer formaldehyde. In addition, formaldehyde is easily polymerized in solution during storage, and must be depolymerized for full use. Therefore, the research on the depolymerization of the polyformaldehyde is of practical significance.
Because the hydroxyl in the molecule of formaldehyde (HCHO) is connected with two hydrogen atoms, the formaldehyde has higher activity than other aldehydes, is easy to oxidize and easy to polymerize, and can generate various polymerization products along with different conditions during polymerization. The formaldehyde aqueous solution (HOCH: OH) is easy to separate out polyformaldehyde after being stored for a long time. The polymerization degree of polyoxymethylene is generally 8 to 100. When the formaldehyde unit is below 12, the polyformaldehyde with smaller molecular weight is soluble in water, and the polyformaldehyde with high molecular weight is insoluble in water to produce formaldehyde solution (the formaldehyde content is 3.0-37.4%), if no formaldehyde polymerization inhibitor is added into the storage tank, the white solid polyformaldehyde with 40-50 t/a of overhaul in the storage tank is generated. The storage tank is difficult to clean due to the gel and formaldehyde odor, and the storage tank is discharged into a storage yard to pollute the environment.
Therefore, during the production of formaldehyde, the formation of polyoxymethylene has a great influence on the system production, but is unavoidable. The formation of polyoxymethylene is caused by various reasons, for example, the catalyst is cracked during the preparation process in the early stage of the process production, and the process index is controlled improperly during the production process, so that the operation is unstable. The formaldehyde device needs to effectively prevent the formation of polyformaldehyde, the formation of the polyformaldehyde influences the good operation of the absorption tower, and the production stability of the whole device can be improved and the yield is improved by controlling the generation of the polyformaldehyde.
In the related technology, a formaldehyde storage tank often generates polyformaldehyde in cold winter, polyformaldehyde is still in a dispersed state, and when a blocky polymer is not formed, polyformaldehyde at the moment is easy to depolymerize, a polyformaldehyde solution cleaned out of the storage tank is placed in a reaction kettle to be heated, and polyformaldehyde can generate depolymerization reaction. The treated polyformaldehyde can be added into a formaldehyde finished product again to be sold as a product. The content of formaldehyde in depolymerization liquid obtained by a better depolymerization method can reach 20 percent at most, and further breakthrough is difficult to be made. The depolymerized liquid after depolymerization can be added into formaldehyde for mixing and selling, and if the content of the formaldehyde in the depolymerized liquid can not be broken through, the quality of the product can be influenced. If the formaldehyde is not mixed with the formaldehyde for sale, serious pollution and waste are caused. Therefore, improvements are urgently needed.
Disclosure of Invention
In order to improve the depolymerization capability of polyformaldehyde in a formaldehyde storage tank and improve the content of formaldehyde in a depolymerization liquid, the application provides a novel polyformaldehyde depolymerization method, which comprises the following steps:
step 1), introducing hot steam or hot water, a mixed solution of monohydric alcohol and a catalyst into polyformaldehyde, then uniformly mixing and preheating, and reacting to obtain a mixed material;
the mass ratio of the mixed liquid of the polyformaldehyde and the monohydric alcohol to the catalyst is 1: (2-3): (0.03-0.05);
and 2) pumping the mixture into a reactor for reaction, keeping the reaction temperature at 70-80 ℃, and finishing the reaction for 15-25 s to obtain depolymerization liquid with the formaldehyde content of more than 55%.
Generally, the depolymerization effect is better when the amounts of the monohydric alcohol mixed solution and the catalyst are larger, but in the experimental process, it is found that the production efficiency is reduced and the formaldehyde content in the depolymerization solution is also affected to a certain extent when the amounts of the monohydric alcohol mixed solution and the catalyst are too large, possibly because a part of formaldehyde is dissolved by excessive alcohol, and the formaldehyde content is reduced. The formaldehyde solution obtained by depolymerizing polyformaldehyde by the method can be used as a raw material of some chemical products, and the content of the obtained formaldehyde solution is higher than the national standard of qualified products (more than 36.5%) of industrial formaldehyde solution, so that the aims of turning harm into benefit and changing waste into valuable are fulfilled.
Preferably, the mixed solution of monohydric alcohol is a mixture of primary alcohol and secondary alcohol.
Preferably, the primary alcohol is a mixture of n-butanol, iso-butanol and neopentyl alcohol in a ratio of 1: (0.5-0.9): (1.2-1.8) in a mass ratio.
Preferably, the secondary alcohol is selected from one or more of 2-butanol, isopropanol and cyclohexanol.
By the specific selection of the primary alcohol and the secondary alcohol, polyformaldehyde is more easily depolymerized, so that depolymerization liquid with higher content of formaldehyde is obtained.
Preferably, the catalyst is selected from sodium carbonate or a compound of more than two of dimethylamine, triethylamine, triethanolamine and diethylamine.
Preferably, the catalyst is prepared from dimethylamine and diethylamine in a ratio of 1: (3-6) in a certain mass ratio.
In the system, the monohydric alcohol mixed liquor with specific proportion, dimethylamine and diethylamine can better promote the depolymerization reaction of polyformaldehyde, reduce the occurrence of side reaction and increase the content of formaldehyde after depolymerization. The energy given by the temperature in the tubular reactor can better increase the solubility of the polyformaldehyde in the monohydric alcohol mixed solution, and simultaneously under the action of dimethylamine and diethylamine, the collision probability of the polyformaldehyde and methanol is increased, so that the chain breaking possibility of the polyformaldehyde is increased, and simultaneously, the reaction degree of the methanol and the formaldehyde is hardly carried out at a specific temperature and in a retention time, so that the depolymerization reaction is increased, and the occurrence of side reactions is reduced.
Preferably, the temperature in step 2) is maintained at 70-75 ℃.
In the invention, the specific temperature is selected, the energy level required by the depolymerization reaction can be better reduced by the catalyst compounded by dimethylamine and diethylamine, and the collision speed of polyformaldehyde and the catalyst is increased, so that the polyformaldehyde can be depolymerized to a greater extent. And the reaction temperature is mild, the hydroxyl of the primary alcohol is not easy to react with the aldehyde-ketone group of the formaldehyde or the polyformaldehyde, and the generation of byproducts is reduced.
Preferably, the reaction time in step 2) is 15 to 20 s.
By controlling the specific residence time, not only is the productivity increased and the energy consumption reduced, but also the depolymerization reaction can be better carried out.
To sum up, this application is 1: (2-3): (0.03-0.05) depolymerizing polyformaldehyde, wherein the obtained formaldehyde solution can be used as a raw material of some chemical products, and the content of the obtained formaldehyde solution is higher than the national standard of qualified products (higher than 36.5%) of industrial formaldehyde solutions, so that the aims of turning harm into benefit and turning waste into wealth are fulfilled. The monohydric alcohol mixed liquor with specific proportion, dimethylamine and diethylamine can better promote the depolymerization reaction of polyformaldehyde, reduce the occurrence of side reaction and increase the content of formaldehyde after depolymerization.
Detailed Description
Examples
Example 1
The embodiment discloses a novel polyformaldehyde depolymerization method, which specifically comprises the following steps:
step 1), introducing hot steam or hot water, a mixed solution of monohydric alcohol and a catalyst into a storage tank containing polyformaldehyde, then uniformly mixing and preheating, and reacting to obtain a mixed material;
the mass ratio of the mixed liquid of polyformaldehyde and monohydric alcohol to the catalyst is 1: 2: 0.03.
and 2) pumping the mixture into a tubular reactor through a pump feeder to react, keeping the reaction temperature at 70 ℃, and finishing the reaction for 15s to obtain depolymerization liquid with the formaldehyde content of 34.2%.
The monohydric alcohol mixed liquor is a compound of primary alcohol (n-butyl alcohol) and secondary alcohol (2-butyl alcohol) in a mass ratio of 1: 2.
The catalyst was dimethylamine.
Example 2
The embodiment discloses a novel polyformaldehyde depolymerization method, which specifically comprises the following steps:
step 1), introducing hot steam or hot water, a mixed solution of monohydric alcohol and a catalyst into a storage tank containing polyformaldehyde, then uniformly mixing and preheating, and reacting to obtain a mixed material;
the mass ratio of the mixed liquid of polyformaldehyde and monohydric alcohol to the catalyst is 1: 3: 0.05;
and 2), pumping the mixture into a tubular reactor through a pump conveyor for reaction, keeping the reaction temperature at 80 ℃, and finishing the reaction for 25s to obtain depolymerization liquid with the formaldehyde content of 35%.
The monohydric alcohol mixed liquor is a compound of primary alcohol (n-butyl alcohol) and secondary alcohol (2-butyl alcohol) in a mass ratio of 1: 3.
The catalyst is dimethylamine.
Example 3
The embodiment discloses a novel polyformaldehyde depolymerization method, which specifically comprises the following steps:
step 1), introducing hot steam or hot water, a mixed solution of monohydric alcohol and a catalyst into a storage tank containing polyformaldehyde, then uniformly mixing and preheating, and reacting to obtain a mixed material;
the mass ratio of the mixed liquid of polyformaldehyde and monohydric alcohol to the catalyst is 1: 2.4: 0.04;
and 2), pumping the mixture into a tubular reactor through a pump conveyor for reaction, keeping the reaction temperature at 72 ℃, and finishing the reaction for 20s to obtain depolymerization liquid with the formaldehyde content of 36.3%.
The monohydric alcohol mixed liquor is a compound of primary alcohol (n-butyl alcohol) and secondary alcohol (2-butyl alcohol) in a mass ratio of 1: 2.
The catalyst was dimethylamine.
Example 4
The embodiment discloses a novel polyformaldehyde depolymerization method, which specifically comprises the following steps:
step 1), introducing hot steam or hot water, a mixed solution of monohydric alcohol and a catalyst into a storage tank containing polyformaldehyde, then uniformly mixing and preheating, and reacting to obtain a mixed material;
the mass ratio of the mixed liquid of polyformaldehyde and monohydric alcohol to the catalyst is 1: 2.4: 0.04;
and 2), pumping the mixture into a tubular reactor through a pump conveyor for reaction, keeping the reaction temperature at 72 ℃, and finishing the reaction for 20s to obtain depolymerization liquid with the formaldehyde content of 35.9%.
The monohydric alcohol mixed liquor is primary alcohol (formed by compounding n-butyl alcohol, isobutyl alcohol and neopentyl alcohol in a mass ratio of 1: 0.5: 1.2) and secondary alcohol (formed by compounding 2-butyl alcohol and isopropanol in a mass ratio of 1: 0.5).
The catalyst was dimethylamine.
Example 5
This example discloses a novel process for the depolymerization of polyoxymethylene, which differs from example 4 in that:
the monohydric alcohol mixed liquor is primary alcohol (formed by compounding n-butyl alcohol, isobutyl alcohol and neopentyl alcohol in a mass ratio of 1: 0.9: 1.8) and secondary alcohol (formed by compounding 2-butyl alcohol and isopropanol in a mass ratio of 1: 0.5).
The depolymerization solution with formaldehyde content of 36.1% is obtained.
Example 6
This example discloses a novel process for the depolymerization of polyoxymethylene, which differs from example 4 in that:
the catalyst is dimethylamine and diethylamine in a ratio of 1:3, and compounding according to the mass ratio.
The depolymerization solution with formaldehyde content of 36.6% is obtained.
Example 7
This example discloses a novel process for the depolymerization of polyoxymethylene, which differs from example 6 in that:
the catalyst is dimethylamine and diethylamine in a ratio of 1: 6, and compounding.
The depolymerization solution with formaldehyde content of 36.9% is obtained.
Comparative example
Comparative example 1
Direct thermal depolymerization: taking a certain amount of polyformaldehyde in a distillation flask, heating to a certain temperature for depolymerization, and absorbing the evaporated steam by using a certain amount of solvent until the solid formaldehyde is completely evaporated. The thermal depolymerization temperature is controlled at about 140 ℃, and the depolymerization products are absorbed by isopropanol. The thermal depolymerization in the solvent is carried out by using a high boiling point solvent (glycerol), and the dosage of the solvent is equal to that of the direct thermal depolymerization absorbent. A method for preparing formaldehyde monomer by thermal depolymerization of polyformaldehyde is disclosed.
The content of formaldehyde in the depolymerization solution obtained by the reaction is 15.4%.
Comparative example 2
S1: adding polyformaldehyde into a mixing kettle, then adding methanol and triethylamine for fully mixing and preheating to obtain a mixed solid material;
s2: pumping the mixed solid material obtained in the step S1 into a tubular reactor through a pump machine for reaction, heating the tubular reactor through hot water, controlling the reaction temperature at 50 ℃ and the retention time of the material at 0.45min, and obtaining depolymerization liquid after the reaction is finished.
Adding the polyformaldehyde into a mixing kettle through a continuous feeder;
the mass ratio of the polyformaldehyde to the methanol to the triethylamine is 1: 0.88: 0.12.
the content of formaldehyde in the depolymerization solution obtained by the reaction is 14%.
Comparative example 3
The difference from example 1 is that the mass ratio of the mixed solution of polyoxymethylene, monohydric alcohol and catalyst is 1: 1.5: 0.02.
the content of formaldehyde in depolymerization liquid obtained by the reaction is 20.2 percent
Experimental detection
Experiment 1 determination of Formaldehyde content
And (3) reacting formaldehyde in the sample with an excessive neutral sodium sulfite solution to generate sodium hydroxide, and titrating by using a sulfuric acid standard titration solution by using thymolphthalein as an indicator.
HCHO+Na 2 SO 3 +H 2 O＝H 2 C(OH)SO 3 Na+NaOH。
2NaOH+H 2 SO 2 ＝Na 2 SO 4 +2H 2 O。
Using the following reagents: sodium sulfite solution: 126 g/L.
126g of anhydrous sodium sulfite is weighed, dissolved in water and diluted to 1L, and shaken up for standby, wherein the effective period of the solution is one week.
Sulfuric acid standard titration solution: c (H) 2 SO 4 )＝0.5mol/L。
Thymolphthalein indicator: 1 g/L.
The experimental steps are as follows: a250 mL Erlenmeyer flask was charged with 50mL of sodium sulfite solution and 3 drops of thymolphthalein indicator and neutralized with a standard titration solution of sulfuric acid until the blue color just disappeared. Weighing 1g of laboratory sample by a subtraction method, accurately weighing the sample to 0.0001g, placing the sample in the conical flask, shaking up, titrating by using a sulfuric acid standard titration solution, and obtaining the end point when blue color just disappears.
And (4) calculating a result: the mass fraction w1 of formaldehyde was calculated by the following formula.
w1＝(V1/1000)c1M/m1*100％
In the formula: v1-value for volume of sulfuric acid standard titration solution in milliliters (mL);
c 1-the exact value of the concentration of the sulfuric acid standard titration solution in moles per liter (mol/L);
m 1-number of sample masses in grams (g);
the molar mass of M-formaldehyde is given in grams per mole (g/moL) (M ═ 30.03).
The arithmetic mean of the results of the two replicates was taken as the reported result. The absolute difference between the two parallel measurements should not be greater than 0.1%.
Experiment 2 determination of methanol content
Under selected operating conditions, the sample is vaporized through a chromatographic column and the components are separated and detected with a hydrogen flame ionization detector. And (4) quantifying by using an internal standard method, and calculating the mass fraction of the methanol.
Reagent: methanol; anhydrous ethanol: an internal standard substance; hydrogen gas: the volume fraction is not less than 99.9 percent, and the product is dried and purified by silica gel and a molecular sieve; nitrogen gas: the volume fraction is not less than 99.95 percent, and the product is dried and purified by silica gel and a molecular sieve; air: drying with silica gel and molecular sieve, and purifying.
The instrument comprises the following steps: gas chromatograph: and an ionization detector is provided, and the sensitivity and stability of the whole machine meet the relevant regulations in GB/T9722.
Sample injector: 1 μ L.
Column and typical chromatographic operating conditions:
the results of the above tests are recorded in table 1.
TABLE 1
| Formaldehyde content (%) | Methanol content (%) | |
| Example 1 | 34.2 | 1.4 |
| Example 2 | 35 | 1.4 |
| Example 3 | 35.3 | 1.4 |
| Example 4 | 35.9 | 1.3 |
| Example 5 | 36.1 | 1.3 |
| Example 6 | 36.6 | 1.1 |
| Example 7 | 36.9 | 1.1 |
| Comparative example 1 | 15.4 | 1.9 |
| Comparative example 2 | 14 | 2.0 |
| Comparative example 3 | 20.2 | 1.5 |
As can be seen from the data in Table 1, comparative examples 1-3 have formaldehyde contents less than examples 1-7 and methanol contents (impurities) higher than examples 1-7, indicating that the mass ratio of polyoxymethylene, mixed liquid of monohydric alcohol and catalyst defined in this application is 1: (2-3): (0.03-0.05), the obtained formaldehyde solution can be used as a raw material of chemical products, so that the purposes of turning harm into benefit and changing waste into valuable are achieved, and the content of the obtained formaldehyde solution is 36.9 percent which is higher than the national standard of 37 percent of qualified products (36.5 percent) of industrial formaldehyde solutions.
Comparing examples 6 and 7 with example 4, it can be seen that the formaldehyde content in examples 6 and 7 is greater than that in example 4, and the methanol content (impurities) is less than that in example 4, which shows that the action of the monohydric alcohol mixed solution, dimethylamine and diethylamine in a specific ratio in the system of the present invention can better promote the depolymerization reaction of polyoxymethylene, reduce the occurrence of side reactions, increase the formaldehyde content after depolymerization, and reduce the impurity content.
The above-described embodiments are merely preferred embodiments of the present invention, which are intended to illustrate the present invention and not to limit the scope of the present invention. The title of the invention has been described with specific examples. The invention can be used for other purposes by those skilled in the art by appropriately changing the raw materials, the process conditions and the like without departing from the content of the invention, and all similar substitutes and modifications obvious to those skilled in the art are deemed to be included in the scope of the invention.
Claims (8)
1. A novel polyoxymethylene depolymerization method is characterized by comprising the following steps:
step 1), introducing hot steam or hot water, a mixed solution of monohydric alcohol and a catalyst into polyformaldehyde, then uniformly mixing and preheating, and reacting to obtain a mixed material;
the mass ratio of the mixed liquid of the polyformaldehyde and the monohydric alcohol to the catalyst is 1: (2-3): (0.03-0.05);
and 2) pumping the mixture into a reactor for reaction, keeping the reaction temperature at 70-80 ℃, and finishing the reaction for 15-25 s to obtain depolymerization liquid with the formaldehyde content of more than 60%.
2. The novel process for depolymerizing polyoxymethylenes according to claim 1, wherein: the mixed solution of the monohydric alcohol is formed by mixing primary alcohol and secondary alcohol.
3. The novel process for depolymerizing polyoxymethylenes according to claim 2, wherein: the primary alcohol is prepared by mixing n-butyl alcohol, isobutyl alcohol and neopentyl alcohol in a ratio of 1: (0.5-0.9): (1.2-1.8) in a mass ratio.
4. The novel process for depolymerizing polyoxymethylenes according to claim 2, wherein: the secondary alcohol is selected from one or more of 2-butanol, isopropanol and cyclohexanol.
5. A novel process for the depolymerization of polyoxymethylenes according to any one of claims 1 to 4, characterized in that: the catalyst is selected from sodium carbonate or a compound of more than two of dimethylamine, triethylamine, triethanolamine and diethylamine.
6. A novel process for the depolymerization of polyoxymethylenes according to any one of claims 1 to 4, characterized in that: the catalyst is prepared from dimethylamine and diethylamine in a weight ratio of 1: (3-6) in a certain mass ratio.
7. The novel process for depolymerizing polyoxymethylenes according to claim 1, wherein: the temperature in step 2) is maintained at 70-75 ℃.
8. The novel process for depolymerizing polyoxymethylenes according to claim 1, wherein: the reaction time in the step 2) is 15-20 s.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116813457A (en) * | 2023-04-21 | 2023-09-29 | 安徽瑞柏新材料有限公司 | Preparation method of anhydrous formaldehyde solution |
| RU2821396C1 (en) * | 2023-08-01 | 2024-06-24 | Акционерное общество "Метафракс Кемикалс" | Method of producing formalin (versions) |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB730602A (en) * | 1951-10-12 | 1955-05-25 | Celanese Corp | Formaldehyde solutions |
| US3128313A (en) * | 1960-12-22 | 1964-04-07 | Du Pont | Preparation of concentrated formaldehyde |
| CN113582822A (en) * | 2021-07-31 | 2021-11-02 | 南通江山农药化工股份有限公司 | Continuous depolymerization method of paraformaldehyde and application thereof |
-
2022
- 2022-04-24 CN CN202210434808.5A patent/CN114853590A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB730602A (en) * | 1951-10-12 | 1955-05-25 | Celanese Corp | Formaldehyde solutions |
| US3128313A (en) * | 1960-12-22 | 1964-04-07 | Du Pont | Preparation of concentrated formaldehyde |
| CN113582822A (en) * | 2021-07-31 | 2021-11-02 | 南通江山农药化工股份有限公司 | Continuous depolymerization method of paraformaldehyde and application thereof |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116813457A (en) * | 2023-04-21 | 2023-09-29 | 安徽瑞柏新材料有限公司 | Preparation method of anhydrous formaldehyde solution |
| RU2821396C1 (en) * | 2023-08-01 | 2024-06-24 | Акционерное общество "Метафракс Кемикалс" | Method of producing formalin (versions) |
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