CN118344542A - Process for preparing paraformaldehyde by spray drying method - Google Patents
Process for preparing paraformaldehyde by spray drying method Download PDFInfo
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- CN118344542A CN118344542A CN202410549820.XA CN202410549820A CN118344542A CN 118344542 A CN118344542 A CN 118344542A CN 202410549820 A CN202410549820 A CN 202410549820A CN 118344542 A CN118344542 A CN 118344542A
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- 229930040373 Paraformaldehyde Natural products 0.000 title claims abstract description 76
- 229920002866 paraformaldehyde Polymers 0.000 title claims abstract description 76
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 25
- 238000000034 method Methods 0.000 title claims abstract description 25
- 238000001694 spray drying Methods 0.000 title claims abstract description 24
- WSFSSNUMVMOOMR-UHFFFAOYSA-N Formaldehyde Chemical compound O=C WSFSSNUMVMOOMR-UHFFFAOYSA-N 0.000 claims abstract description 189
- 239000008098 formaldehyde solution Substances 0.000 claims abstract description 99
- 238000001704 evaporation Methods 0.000 claims abstract description 56
- 230000008020 evaporation Effects 0.000 claims abstract description 56
- 238000002156 mixing Methods 0.000 claims abstract description 33
- 238000001035 drying Methods 0.000 claims abstract description 32
- 230000003797 telogen phase Effects 0.000 claims abstract description 28
- 239000003054 catalyst Substances 0.000 claims abstract description 22
- 238000010992 reflux Methods 0.000 claims abstract description 20
- 238000002360 preparation method Methods 0.000 claims abstract description 14
- 238000001816 cooling Methods 0.000 claims abstract description 10
- 238000003756 stirring Methods 0.000 claims description 47
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 40
- XEKOWRVHYACXOJ-UHFFFAOYSA-N Ethyl acetate Chemical compound CCOC(C)=O XEKOWRVHYACXOJ-UHFFFAOYSA-N 0.000 claims description 33
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 33
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 30
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 claims description 30
- 239000000463 material Substances 0.000 claims description 30
- 238000005469 granulation Methods 0.000 claims description 28
- 230000003179 granulation Effects 0.000 claims description 28
- 239000007921 spray Substances 0.000 claims description 28
- 239000007790 solid phase Substances 0.000 claims description 26
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 claims description 22
- VHYFNPMBLIVWCW-UHFFFAOYSA-N 4-Dimethylaminopyridine Chemical compound CN(C)C1=CC=NC=C1 VHYFNPMBLIVWCW-UHFFFAOYSA-N 0.000 claims description 20
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 20
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 20
- 239000008367 deionised water Substances 0.000 claims description 20
- 229910021641 deionized water Inorganic materials 0.000 claims description 20
- LNTHITQWFMADLM-UHFFFAOYSA-N gallic acid Chemical compound OC(=O)C1=CC(O)=C(O)C(O)=C1 LNTHITQWFMADLM-UHFFFAOYSA-N 0.000 claims description 20
- 239000011552 falling film Substances 0.000 claims description 16
- 238000005406 washing Methods 0.000 claims description 15
- -1 n-octanoyl Chemical group 0.000 claims description 12
- 239000003208 petroleum Substances 0.000 claims description 11
- 238000001556 precipitation Methods 0.000 claims description 11
- ULTHEAFYOOPTTB-UHFFFAOYSA-N 1,4-dibromobutane Chemical compound BrCCCCBr ULTHEAFYOOPTTB-UHFFFAOYSA-N 0.000 claims description 10
- OSSNTDFYBPYIEC-UHFFFAOYSA-N 1-ethenylimidazole Chemical compound C=CN1C=CN=C1 OSSNTDFYBPYIEC-UHFFFAOYSA-N 0.000 claims description 10
- QOSSAOTZNIDXMA-UHFFFAOYSA-N Dicylcohexylcarbodiimide Chemical compound C1CCCCC1N=C=NC1CCCCC1 QOSSAOTZNIDXMA-UHFFFAOYSA-N 0.000 claims description 10
- 239000004372 Polyvinyl alcohol Substances 0.000 claims description 10
- 235000019441 ethanol Nutrition 0.000 claims description 10
- 238000001914 filtration Methods 0.000 claims description 10
- 229940074391 gallic acid Drugs 0.000 claims description 10
- 235000004515 gallic acid Nutrition 0.000 claims description 10
- 229920002451 polyvinyl alcohol Polymers 0.000 claims description 10
- 239000006228 supernatant Substances 0.000 claims description 10
- 238000009835 boiling Methods 0.000 claims description 8
- 239000000203 mixture Substances 0.000 claims description 8
- 238000006243 chemical reaction Methods 0.000 claims description 6
- NWUYHJFMYQTDRP-UHFFFAOYSA-N 1,2-bis(ethenyl)benzene;1-ethenyl-2-ethylbenzene;styrene Chemical compound C=CC1=CC=CC=C1.CCC1=CC=CC=C1C=C.C=CC1=CC=CC=C1C=C NWUYHJFMYQTDRP-UHFFFAOYSA-N 0.000 claims description 5
- 239000003456 ion exchange resin Substances 0.000 claims description 5
- 229920003303 ion-exchange polymer Polymers 0.000 claims description 5
- 239000007791 liquid phase Substances 0.000 claims description 5
- 239000012299 nitrogen atmosphere Substances 0.000 claims description 5
- 238000000746 purification Methods 0.000 claims description 5
- 238000001291 vacuum drying Methods 0.000 claims description 4
- VMUZVGRNTPFTKE-UHFFFAOYSA-N octanehydrazide Chemical compound CCCCCCCC(=O)NN VMUZVGRNTPFTKE-UHFFFAOYSA-N 0.000 claims 1
- 238000006116 polymerization reaction Methods 0.000 abstract description 22
- 238000005507 spraying Methods 0.000 abstract description 2
- 239000000243 solution Substances 0.000 description 25
- 230000001276 controlling effect Effects 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 5
- 239000000047 product Substances 0.000 description 5
- ZMANZCXQSJIPKH-UHFFFAOYSA-N Triethylamine Chemical group CCN(CC)CC ZMANZCXQSJIPKH-UHFFFAOYSA-N 0.000 description 3
- 239000002608 ionic liquid Substances 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 3
- 229910052742 iron Inorganic materials 0.000 description 3
- 229910003473 lithium bis(trifluoromethanesulfonyl)imide Inorganic materials 0.000 description 3
- QSZMZKBZAYQGRS-UHFFFAOYSA-N lithium;bis(trifluoromethylsulfonyl)azanide Chemical compound [Li+].FC(F)(F)S(=O)(=O)[N-]S(=O)(=O)C(F)(F)F QSZMZKBZAYQGRS-UHFFFAOYSA-N 0.000 description 3
- 125000000217 alkyl group Chemical group 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 150000001450 anions Chemical class 0.000 description 1
- 238000006555 catalytic reaction Methods 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 125000002883 imidazolyl group Chemical group 0.000 description 1
- 230000000415 inactivating effect Effects 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 230000002427 irreversible effect Effects 0.000 description 1
- 238000013021 overheating Methods 0.000 description 1
- 239000000575 pesticide Substances 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G2/00—Addition polymers of aldehydes or cyclic oligomers thereof or of ketones; Addition copolymers thereof with less than 50 molar percent of other substances
- C08G2/08—Polymerisation of formaldehyde
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D1/00—Evaporating
- B01D1/26—Multiple-effect evaporating
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D1/00—Evaporating
- B01D1/30—Accessories for evaporators ; Constructional details thereof
-
- 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
- B01J2/00—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic
- B01J2/02—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic by dividing the liquid material into drops, e.g. by spraying, and solidifying the drops
- B01J2/04—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic by dividing the liquid material into drops, e.g. by spraying, and solidifying the drops in a gaseous medium
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G2/00—Addition polymers of aldehydes or cyclic oligomers thereof or of ketones; Addition copolymers thereof with less than 50 molar percent of other substances
- C08G2/04—Polymerisation by using compounds which act upon the molecular weight, e.g. chain-transferring agents
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G2/00—Addition polymers of aldehydes or cyclic oligomers thereof or of ketones; Addition copolymers thereof with less than 50 molar percent of other substances
- C08G2/06—Catalysts
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention discloses a process for preparing paraformaldehyde by a spray drying method, and belongs to the technical field of paraformaldehyde preparation. The method comprises the following steps: refluxing formaldehyde solution with the mass concentration of 45-60%; cooling the formaldehyde solution after the reflux, adding a telogen, and performing one-stage evaporation concentration; mixing the formaldehyde solution after the first-stage evaporation concentration and the telogen, and carrying out the second-stage evaporation concentration; mixing the concentrated formaldehyde solution and the catalyst, then spraying and granulating, and conveying to a fluidized bed for drying to obtain the paraformaldehyde; the paraformaldehyde self-polymerization is inhibited by adding the telogen for a plurality of times in the concentration stage, so that the paraformaldehyde with low polymerization degree is obtained.
Description
Technical Field
The invention belongs to the technical field of paraformaldehyde preparation, and particularly relates to a process for preparing paraformaldehyde by a spray drying method.
Background
The initial production mode of the paraformaldehyde in China is a rake dryer process, but the method has the problems of severe operation environment, serious dust pollution, insufficient water solubility of products, low single-set yield and the like. Along with the rapid development of national economy, especially the rapid increase of the demand of industries such as pesticides, resins, coatings and the like for paraformaldehyde, a plurality of spray granulation drying method devices are introduced in China for meeting market demands and improving product quality.
The devices finally produce finished paraformaldehyde through the technological processes of concentration of formaldehyde aqueous solution, spray granulation, fluidized bed drying and the like. After being introduced into a spray granulation drying method device, the production process of the paraformaldehyde in China is obviously improved. The core of the process is that the formaldehyde aqueous solution is concentrated and is quickly dried in hot air in a spray granulation mode to form granular paraformaldehyde. The process not only improves the water solubility of the paraformaldehyde, but also ensures that the granularity of the product is more uniform, thereby improving the stability and the fluidity of the product.
However, there is also a risk of local overheating during the preparation of paraformaldehyde using the spray drying apparatus. When the paraformaldehyde is heated to a certain temperature, self-polymerization reaction may be initiated, so that the polymerization degree of the paraformaldehyde is too high, the length of a molecular chain is increased along with the increase of the polymerization degree, the interaction force among molecules is enhanced, and the solubility of the paraformaldehyde in water is reduced.
Disclosure of Invention
The invention discloses a process for preparing paraformaldehyde by a spray drying method, and belongs to the technical field of paraformaldehyde preparation. The method comprises the following steps: refluxing formaldehyde solution with the mass concentration of 45-60%; cooling the formaldehyde solution after the reflux, adding a telogen, and performing one-stage evaporation concentration; mixing the formaldehyde solution after the first-stage evaporation concentration and the telogen, and carrying out the second-stage evaporation concentration; mixing the concentrated formaldehyde solution and the catalyst, then spraying and granulating, and conveying to a fluidized bed for drying to obtain the paraformaldehyde; the paraformaldehyde self-polymerization is inhibited by adding the telogen for a plurality of times in the concentration stage, so that the paraformaldehyde with low polymerization degree is obtained.
The invention aims to solve the technical problems: how to inhibit self-polymerization of paraformaldehyde and obtain paraformaldehyde with low polymerization degree.
The aim of the invention can be achieved by the following technical scheme:
A process for preparing paraformaldehyde by a spray drying method, which comprises the following steps:
S1, introducing formaldehyde solution with the mass concentration of 45-60% into a depolymerization kettle at 50-60 ℃, controlling the temperature of formaldehyde in the depolymerization kettle at 100 ℃, and refluxing for 3-4h in a boiling state;
S2, cooling the formaldehyde solution after reflux, adding a telogen accounting for 0.5-1.5% of the formaldehyde solution in mass content when the temperature of the formaldehyde solution reaches 55-65 ℃, stirring for 10-15min, feeding into a first-stage falling film evaporator, and performing first-stage evaporation concentration;
S3, mixing the formaldehyde solution subjected to the first-stage evaporation concentration and a telogen accounting for 0.5-0.8% of the formaldehyde mass content in the formaldehyde solution subjected to the first-stage evaporation concentration, stirring for 10-15min, feeding into a second-stage falling film evaporator, and carrying out second-stage evaporation concentration;
s4, mixing the formaldehyde solution after the second-stage evaporation concentration and a catalyst accounting for 1.2-1.5% of the formaldehyde mass content in the formaldehyde solution after the second-stage evaporation concentration for 10-15min, and then introducing the mixture into a spray granulation tower for spray granulation to obtain a paraformaldehyde solid phase, wherein the temperature in the spray granulation tower is 40-45 ℃ and the pressure is 270-300Pa;
And S5, conveying the solid phase of the paraformaldehyde to a fluidized bed for drying, and obtaining the paraformaldehyde.
As a preferred technical scheme of the invention, the preparation of the telogen comprises the following steps:
S231, mixing gallic acid, polyvinyl alcohol, 4-dimethylaminopyridine and toluene, stirring for 2-3 hours, adding dicyclohexylcarbodiimide, stirring for 2-3 hours, centrifuging, taking supernatant, putting the supernatant into an ethanol solution with the volume fraction of 95%, adding n-octanoyl hydrazide, stirring for 2-3 hours, adding a hydrochloric acid solution with the concentration of 2-4mol/L, performing gradient precipitation purification by ethyl acetate and petroleum ether, washing, and drying to obtain a material A;
S232, placing the material A, methanol and deionized water into a reaction kettle, stirring for 1-2h, adding formaldehyde solution with the mass fraction of 49.8-52.3% and sulfuric acid solution with the concentration of 2-4mol/L, reacting for 6-8h at 50-55 ℃, then treating by ion exchange resin, and taking a liquid phase to obtain the telogen.
In a preferred embodiment of the present invention, in step S231, the dosage ratio of the gallic acid, polyvinyl alcohol, 4-dimethylaminopyridine, toluene, dicyclohexylcarbodiimide, ethanol solution, n-octanoylhydrazide, and hydrochloric acid solution is 4-6mmol:3-4mmol:0.5-0.6mmol:30-40mL:5-6mmol:20-30mL:14-16mmol:4-6mmol.
In step S232, as a preferred technical solution of the present invention, the proportioning ratio of the material a, methanol, deionized water, formaldehyde solution, and sulfuric acid solution is 4-6mg:30-40mL:30-40mL:15-20mL:6-8mL.
As a preferred technical scheme of the invention, the preparation of the catalyst comprises the following steps:
S41, mixing 1-vinylimidazole, 1, 4-dibromobutane and absolute ethyl alcohol in a nitrogen atmosphere, stirring in a water bath at 55-60 ℃ for 12-16 hours, filtering, taking a solid phase for washing, and drying to obtain a material B;
S42, mixing the material B with deionized water, stirring for 1-2h, adding lithium bistrifluoromethane sulfonyl imide, stirring for 20-24h in a water bath at 65 ℃, filtering, washing a solid phase, and vacuum drying to obtain the catalyst.
As a preferable technical scheme of the invention, in the step S41, the dosage ratio of the 1-vinyl imidazole, the 1, 4-dibromobutane and the absolute ethyl alcohol is 0.15-0.25mol:0.1 to 0.12mol:10-15mL.
As a preferable technical scheme of the invention, in the step S42, the proportioning ratio of the material B, deionized water and lithium bistrifluoromethane sulfonyl imide is 0.1-0.15mol:150mL:0.2-0.22mol.
As a preferable technical scheme of the invention, in the step S5, the drying temperature is 55-60 ℃.
As a preferable technical scheme of the invention, in the step S2, the one-stage evaporation concentration refers to concentration to 50-65% of the mass of the formaldehyde solution in the step S1.
As a preferable technical scheme of the invention, in the step S3, the second-stage evaporation concentration refers to concentration to 75-85% of the mass of the formaldehyde solution in the step S2.
The invention has the beneficial effects that:
According to the process for preparing the paraformaldehyde by using the spray drying method, a large number of hydroxyl groups are introduced into the molecular structure of the telomerizer, and the complex formed by the hydroxyl groups and iron ions which fall off from a pipeline in the formaldehyde conveying process is used for inactivating the iron ions, so that the catalysis of the iron ions on the paraformaldehyde is reduced, and the irreversible self-polymerization reaction of the paraformaldehyde is inhibited; by introducing a multi-ring structure into the molecular structure of the telomering agent, the steric hindrance of self-polymerization of the paraformaldehyde is increased, the chain growth of the paraformaldehyde is hindered, the self-polymerization reaction of the paraformaldehyde is inhibited, and the polymerization degree of the paraformaldehyde is reduced; meanwhile, the alkyl side chain of the imidazole ring of the ionic liquid catalyst is shortened, the distance between anions and cations is reduced, the molecular volume of the ionic liquid is gradually reduced, and the ionic liquid with the short alkyl side chain is beneficial to regulating and controlling the product selectivity in the reaction process, so that the formaldehyde polymerization process is promoted to develop towards paraformaldehyde with low polymerization degree.
Detailed Description
In order to further describe the technical means and effects adopted by the present invention for achieving the intended purpose, the following detailed description is given below with reference to the embodiments, structures, features and effects according to the present invention.
Example 1
A process for preparing paraformaldehyde by a spray drying method, which comprises the following steps:
s1, introducing formaldehyde solution with the mass concentration of 45% into a depolymerization kettle at 50 ℃, controlling the temperature of formaldehyde in the depolymerization kettle at 100 ℃, and refluxing for 3 hours in a boiling state;
S2, cooling the formaldehyde solution after reflux, adding a telogen accounting for 0.5% of the mass content of formaldehyde in the formaldehyde solution when the temperature of the formaldehyde solution reaches 55 ℃, stirring for 10min, feeding the formaldehyde solution into a first-stage falling film evaporator, and carrying out one-stage evaporation concentration until the mass of the formaldehyde solution in the step S1 is 50%;
S3, mixing the formaldehyde solution subjected to the first-stage evaporation concentration and a telogen accounting for 0.5% of the mass content of formaldehyde in the formaldehyde solution subjected to the first-stage evaporation concentration, stirring for 10min, feeding into a second-stage falling film evaporator, and performing the second-stage evaporation concentration to 75% of the mass of the formaldehyde solution in the step S2;
S4, mixing the formaldehyde solution subjected to the second-stage evaporation concentration and a catalyst accounting for 1.2% of the mass content of formaldehyde in the formaldehyde solution subjected to the second-stage evaporation concentration for 10min, and then introducing the mixture into a spray granulation tower for spray granulation to obtain a paraformaldehyde solid phase, wherein the temperature in the spray granulation tower is 40 ℃ and the pressure is 270Pa;
And S5, conveying the solid phase of the paraformaldehyde to a fluidized bed for drying, wherein the drying temperature is 55 ℃, and obtaining the paraformaldehyde with the polymerization degree of 9.
The preparation of the telogen comprises the following steps:
Mixing gallic acid, polyvinyl alcohol, 4-dimethylaminopyridine and toluene, stirring for 2 hours, adding dicyclohexylcarbodiimide, stirring for 2 hours, centrifuging, taking supernatant, putting the supernatant into an ethanol solution with the volume fraction of 95%, adding n-octanoyl hydrazide, stirring for 2 hours, adding a hydrochloric acid solution with the concentration of 2mol/L, performing gradient precipitation purification by ethyl acetate and petroleum ether, washing, and drying to obtain a material A; the dosage ratio of the gallic acid, the polyvinyl alcohol, the 4-dimethylaminopyridine, the toluene, the dicyclohexylcarbodiimide, the ethanol solution, the n-octanoyl hydrazide and the hydrochloric acid solution is 4mmol:3mmol:0.5mmol:30mL:5mmol:20mL:14mmol:4mmol; the gradient precipitation of the ethyl acetate and the petroleum ether refers to the volume ratio of petroleum ether and ethyl acetate in the gradient precipitation process is sequentially 4: 1. 1: 3. 0:1, a step of;
Placing the material A, methanol and deionized water into a reaction kettle, stirring for 1h, adding a formaldehyde solution with the mass fraction of 49.8% and a sulfuric acid solution with the concentration of 2mol/L, reacting at 50 ℃ for 6h, then treating by ion exchange resin, and taking a liquid phase to obtain the telogen; the proportioning ratio of the material A, methanol, deionized water, formaldehyde solution and sulfuric acid solution is 4mg:30mL:30mL:15mL:6mL.
The preparation of the catalyst comprises the following steps:
Mixing 1-vinylimidazole, 1, 4-dibromobutane and absolute ethyl alcohol in a nitrogen atmosphere, stirring in a water bath at 55 ℃ for 12 hours, filtering, taking a solid phase for washing, and drying to obtain a material B; the dosage ratio of the 1-vinylimidazole to the 1, 4-dibromobutane to the absolute ethyl alcohol is 0.15mol:0.1mol:10mL;
Mixing the material B with deionized water, stirring for 1h, adding lithium bistrifluoromethane sulfonyl imide, stirring for 20h in a water bath at 65 ℃, filtering, washing a solid phase, and vacuum drying to obtain the catalyst; the proportioning ratio of the material B, deionized water and lithium bis (trifluoromethanesulfonyl) imide is 0.1mol:150mL:0.2mol.
Example 2
A process for preparing paraformaldehyde by a spray drying method, which comprises the following steps:
S1, introducing formaldehyde solution with the mass concentration of 55% into a depolymerization kettle at 55 ℃, controlling the temperature of formaldehyde in the depolymerization kettle at 100 ℃, and refluxing for 3.5 hours in a boiling state;
S2, cooling the formaldehyde solution after reflux, adding a telogen accounting for 1% of the mass content of formaldehyde in the formaldehyde solution when the temperature of the formaldehyde solution reaches 60 ℃, stirring for 12min, feeding into a first-stage falling film evaporator, and performing first-stage evaporation concentration until the mass of the formaldehyde solution in the step S1 is 60%;
S3, mixing the formaldehyde solution subjected to the first-stage evaporation concentration and a telogen accounting for 0.65% of the mass content of formaldehyde in the formaldehyde solution subjected to the first-stage evaporation concentration, stirring for 12min, feeding into a second-stage falling film evaporator, and performing the second-stage evaporation concentration until the mass of the formaldehyde solution in the step S2 is 80%;
S4, mixing the formaldehyde solution after the second-stage evaporation concentration and a catalyst accounting for 1.35% of the formaldehyde mass content in the formaldehyde solution after the second-stage evaporation concentration for 12min, and then introducing the mixture into a spray granulation tower for spray granulation to obtain a paraformaldehyde solid phase, wherein the temperature in the spray granulation tower is 42 ℃ and the pressure is 285Pa;
And S5, conveying the solid phase of the paraformaldehyde to a fluidized bed for drying, wherein the drying temperature is 58 ℃, and obtaining the paraformaldehyde with the polymerization degree of 11.
The preparation of the telogen comprises the following steps:
Mixing gallic acid, polyvinyl alcohol, 4-dimethylaminopyridine and toluene, stirring for 2.5 hours, adding dicyclohexylcarbodiimide, stirring for 2.5 hours, centrifuging, taking supernatant, putting the supernatant into an ethanol solution with the volume fraction of 95%, adding n-octanoyl hydrazide, stirring for 2.5 hours, adding a hydrochloric acid solution with the concentration of 3mol/L, carrying out gradient precipitation purification by ethyl acetate and petroleum ether, washing, and drying to obtain a material A; the dosage ratio of the gallic acid, the polyvinyl alcohol, the 4-dimethylaminopyridine, the toluene, the dicyclohexylcarbodiimide, the ethanol solution, the n-octanoyl hydrazide and the hydrochloric acid solution is 5mmol:3.5mmol:0.55mmol:35mL:5.5mmol:25mL:15mmol:5mmol; the gradient precipitation of the ethyl acetate and the petroleum ether refers to the volume ratio of petroleum ether and ethyl acetate in the gradient precipitation process is sequentially 4: 1. 1: 3. 0:1, a step of;
placing the material A, methanol and deionized water into a reaction kettle, stirring for 1.5h, adding a formaldehyde solution with the mass fraction of 50.7% and a sulfuric acid solution with the concentration of 3mol/L, reacting at 53 ℃ for 7h, then treating by ion exchange resin, and taking a liquid phase to obtain the telogen; the proportioning ratio of the material A, methanol, deionized water, formaldehyde solution and sulfuric acid solution is 5mg:35mL:35mL:18mL:7mL.
The preparation of the catalyst comprises the following steps:
Mixing 1-vinylimidazole, 1, 4-dibromobutane and absolute ethyl alcohol in a nitrogen atmosphere, stirring in a water bath at 58 ℃ for 14 hours, filtering, washing a solid phase, and drying to obtain a material B; the dosage ratio of the 1-vinylimidazole to the 1, 4-dibromobutane to the absolute ethanol is 0.2mol:0.11mol:13mL;
Mixing the material B with deionized water, stirring for 1.5h, adding lithium bistrifluoromethane sulfonyl imide, stirring for 22h in a water bath at 65 ℃, filtering, washing a solid phase, and vacuum drying to obtain the catalyst; the proportioning ratio of the material B, deionized water and lithium bis (trifluoromethanesulfonyl) imide is 0.13mol:150mL:0.21mol.
Example 3
A process for preparing paraformaldehyde by a spray drying method, which comprises the following steps:
s1, introducing formaldehyde solution with the mass concentration of 60% into a depolymerization kettle at 60 ℃, controlling the temperature of formaldehyde in the depolymerization kettle at 100 ℃, and refluxing for 4 hours in a boiling state;
s2, cooling the formaldehyde solution after reflux, adding a telogen accounting for 1.5% of the mass content of formaldehyde in the formaldehyde solution when the temperature of the formaldehyde solution reaches 65 ℃, stirring for 15min, feeding the formaldehyde solution into a first-stage falling film evaporator, and carrying out one-stage evaporation concentration until the mass of the formaldehyde solution in the step S1 is 65%;
S3, mixing the formaldehyde solution subjected to the first-stage evaporation concentration and a telogen accounting for 0.8% of the mass content of formaldehyde in the formaldehyde solution subjected to the first-stage evaporation concentration, stirring for 15min, feeding into a second-stage falling film evaporator, and performing the second-stage evaporation concentration until the mass of the formaldehyde solution in the step S2 is 85%;
S4, mixing the formaldehyde solution subjected to the second-stage evaporation concentration and a catalyst accounting for 1.5% of the mass content of formaldehyde in the formaldehyde solution subjected to the second-stage evaporation concentration for 15min, and then introducing the mixture into a spray granulation tower for spray granulation to obtain a paraformaldehyde solid phase, wherein the temperature in the spray granulation tower is 45 ℃ and the pressure is 300Pa;
and S5, conveying the solid phase of the paraformaldehyde to a fluidized bed for drying, wherein the drying temperature is 60 ℃, and obtaining the paraformaldehyde with the polymerization degree of 14.
The preparation of the telogen comprises the following steps:
Mixing gallic acid, polyvinyl alcohol, 4-dimethylaminopyridine and toluene, stirring for 3 hours, adding dicyclohexylcarbodiimide, stirring for 3 hours, centrifuging, taking supernatant, putting the supernatant into an ethanol solution with the volume fraction of 95%, adding n-octanoyl hydrazide, stirring for 3 hours, adding a hydrochloric acid solution with the concentration of 4mol/L, performing gradient precipitation purification by ethyl acetate and petroleum ether, washing, and drying to obtain a material A; the dosage ratio of the gallic acid, the polyvinyl alcohol, the 4-dimethylaminopyridine, the toluene, the dicyclohexylcarbodiimide, the ethanol solution, the n-octanoyl hydrazide and the hydrochloric acid solution is 6mmol:4mmol:0.6mmol:40mL:6mmol:30mL:16mmol:6mmol; the gradient precipitation of the ethyl acetate and the petroleum ether refers to the volume ratio of petroleum ether and ethyl acetate in the gradient precipitation process is sequentially 4: 1. 1: 3. 0:1, a step of;
Placing the material A, methanol and deionized water into a reaction kettle, stirring for 2 hours, adding a formaldehyde solution with the mass fraction of 52.3% and a sulfuric acid solution with the concentration of 4mol/L, reacting at 55 ℃ for 8 hours, then treating by ion exchange resin, and taking a liquid phase to obtain the telogen; the proportioning ratio of the material A, methanol, deionized water, formaldehyde solution and sulfuric acid solution is 6mg:40mL:40mL:20mL:8mL.
The preparation of the catalyst comprises the following steps:
Mixing 1-vinylimidazole, 1, 4-dibromobutane and absolute ethyl alcohol in a nitrogen atmosphere, stirring for 16 hours in a water bath at 60 ℃, filtering, taking a solid phase for washing, and drying to obtain a material B; the dosage ratio of the 1-vinylimidazole to the 1, 4-dibromobutane to the absolute ethanol is 0.25mol:0.12mol:15mL;
mixing the material B with deionized water, stirring for 2 hours, adding lithium bistrifluoromethane sulfonyl imide, stirring for 24 hours in a water bath at 65 ℃, filtering, washing a solid phase, and drying in vacuum to obtain the catalyst; the proportioning ratio of the material B, deionized water and lithium bis (trifluoromethanesulfonyl) imide is 0.15mol:150mL:0.22mol.
Comparative example 1
The difference from example 1 is that a spray drying process for preparing paraformaldehyde comprises the following steps:
s1, introducing formaldehyde solution with the mass concentration of 45% into a depolymerization kettle at 50 ℃, controlling the temperature of formaldehyde in the depolymerization kettle at 100 ℃, and refluxing for 3 hours in a boiling state;
s2, cooling the formaldehyde solution after reflux, feeding the formaldehyde solution into a first-stage falling film evaporator when the temperature of the formaldehyde solution reaches 55 ℃, and carrying out first-stage evaporation concentration until the mass of the formaldehyde solution in the step S1 is 50%;
S3, mixing the formaldehyde solution subjected to the first-stage evaporation concentration and a telogen accounting for 0.5% of the mass content of formaldehyde in the formaldehyde solution subjected to the first-stage evaporation concentration, stirring for 10min, feeding into a second-stage falling film evaporator, and performing the second-stage evaporation concentration to 75% of the mass of the formaldehyde solution in the step S2;
S4, mixing the formaldehyde solution subjected to the second-stage evaporation concentration and a catalyst accounting for 1.2% of the mass content of formaldehyde in the formaldehyde solution subjected to the second-stage evaporation concentration for 10min, and then introducing the mixture into a spray granulation tower for spray granulation to obtain a paraformaldehyde solid phase, wherein the temperature in the spray granulation tower is 40 ℃ and the pressure is 270Pa;
And S5, conveying the solid phase of the paraformaldehyde to a fluidized bed for drying, wherein the drying temperature is 55 ℃, and obtaining the paraformaldehyde with the polymerization degree of 38.
Comparative example 2
The difference from example 1 is that a spray drying process for preparing paraformaldehyde comprises the following steps:
s1, introducing formaldehyde solution with the mass concentration of 45% into a depolymerization kettle at 50 ℃, controlling the temperature of formaldehyde in the depolymerization kettle at 100 ℃, and refluxing for 3 hours in a boiling state;
S2, cooling the formaldehyde solution after reflux, adding a telogen accounting for 0.5% of the mass content of formaldehyde in the formaldehyde solution when the temperature of the formaldehyde solution reaches 55 ℃, stirring for 10min, feeding the formaldehyde solution into a first-stage falling film evaporator, and carrying out one-stage evaporation concentration until the mass of the formaldehyde solution in the step S1 is 50%;
S3, feeding the formaldehyde solution subjected to the first-stage evaporation concentration into a second-stage falling film evaporator, and performing the second-stage evaporation concentration to 75% of the mass of the formaldehyde solution in the step S2;
S4, mixing the formaldehyde solution subjected to the second-stage evaporation concentration and a catalyst accounting for 1.2% of the mass content of formaldehyde in the formaldehyde solution subjected to the second-stage evaporation concentration for 10min, and then introducing the mixture into a spray granulation tower for spray granulation to obtain a paraformaldehyde solid phase, wherein the temperature in the spray granulation tower is 40 ℃ and the pressure is 270Pa;
And S5, conveying the solid phase of the paraformaldehyde to a fluidized bed for drying, wherein the drying temperature is 55 ℃, and obtaining the paraformaldehyde with the polymerization degree of 41.
Comparative example 3
The difference from comparative example 1 is that a spray drying process for preparing paraformaldehyde comprises the following steps:
s1, introducing formaldehyde solution with the mass concentration of 45% into a depolymerization kettle at 50 ℃, controlling the temperature of formaldehyde in the depolymerization kettle at 100 ℃, and refluxing for 3 hours in a boiling state;
s2, cooling the formaldehyde solution after reflux, feeding the formaldehyde solution into a first-stage falling film evaporator when the temperature of the formaldehyde solution reaches 55 ℃, and carrying out first-stage evaporation concentration until the mass of the formaldehyde solution in the step S1 is 50%;
S3, feeding the formaldehyde solution subjected to the first-stage evaporation concentration into a second-stage falling film evaporator, and performing the second-stage evaporation concentration to 75% of the mass of the formaldehyde solution in the step S2;
S4, mixing the formaldehyde solution subjected to the second-stage evaporation concentration and a catalyst accounting for 1.2% of the mass content of formaldehyde in the formaldehyde solution subjected to the second-stage evaporation concentration for 10min, and then introducing the mixture into a spray granulation tower for spray granulation to obtain a paraformaldehyde solid phase, wherein the temperature in the spray granulation tower is 40 ℃ and the pressure is 270Pa;
And S5, conveying the solid phase of the paraformaldehyde to a fluidized bed for drying, wherein the drying temperature is 55 ℃, and obtaining the paraformaldehyde with the polymerization degree of 53.
Comparative example 4
The difference from example 1 is that the catalyst is triethylamine, a paraformaldehyde having a degree of polymerization of 40 is obtained.
The present invention is not limited to the above embodiments, but is capable of modification and variation in detail, and other modifications and variations can be made by those skilled in the art without departing from the scope of the present invention.
Claims (10)
1. A process for preparing paraformaldehyde by a spray drying method, which is characterized by comprising the following steps of:
S1, introducing formaldehyde solution with the mass concentration of 45-60% into a depolymerization kettle at 50-60 ℃, controlling the temperature of formaldehyde in the depolymerization kettle at 100 ℃, and refluxing for 3-4h in a boiling state;
S2, cooling the formaldehyde solution after reflux, adding a telogen accounting for 0.5-1.5% of the formaldehyde solution in mass content when the temperature of the formaldehyde solution reaches 55-65 ℃, stirring for 10-15min, feeding into a first-stage falling film evaporator, and performing first-stage evaporation concentration;
S3, mixing the formaldehyde solution subjected to the first-stage evaporation concentration and a telogen accounting for 0.5-0.8% of the formaldehyde mass content in the formaldehyde solution subjected to the first-stage evaporation concentration, stirring for 10-15min, feeding into a second-stage falling film evaporator, and carrying out second-stage evaporation concentration;
s4, mixing the formaldehyde solution after the second-stage evaporation concentration and a catalyst accounting for 1.2-1.5% of the formaldehyde mass content in the formaldehyde solution after the second-stage evaporation concentration for 10-15min, and then introducing the mixture into a spray granulation tower for spray granulation to obtain a paraformaldehyde solid phase, wherein the temperature in the spray granulation tower is 40-45 ℃ and the pressure is 270-300Pa;
And S5, conveying the solid phase of the paraformaldehyde to a fluidized bed for drying, and obtaining the paraformaldehyde.
2. The process for preparing paraformaldehyde by a spray drying method according to claim 1, characterized in that the preparation of the telogen comprises the following steps:
S231, mixing gallic acid, polyvinyl alcohol, 4-dimethylaminopyridine and toluene, stirring for 2-3 hours, adding dicyclohexylcarbodiimide, stirring for 2-3 hours, centrifuging, taking supernatant, putting the supernatant into an ethanol solution with the volume fraction of 95%, adding n-octanoyl hydrazide, stirring for 2-3 hours, adding a hydrochloric acid solution with the concentration of 2-4mol/L, performing gradient precipitation purification by ethyl acetate and petroleum ether, washing, and drying to obtain a material A;
S232, placing the material A, methanol and deionized water into a reaction kettle, stirring for 1-2h, adding formaldehyde solution with the mass fraction of 49.8-52.3% and sulfuric acid solution with the concentration of 2-4mol/L, reacting for 6-8h at 50-55 ℃, then treating by ion exchange resin, and taking a liquid phase to obtain the telogen.
3. The process for preparing paraformaldehyde by spray drying according to claim 2, wherein in step S231, the dosage ratio of gallic acid, polyvinyl alcohol, 4-dimethylaminopyridine, toluene, dicyclohexylcarbodiimide, ethanol solution, n-octanoylhydrazine, hydrochloric acid solution is 4-6 mmol: 3-4 mmol: 0.5-0.6mmol:30-40mL:5-6mmol:20-30mL:14-16mmol:4-6mmol.
4. The process for preparing paraformaldehyde by spray drying according to claim 2, wherein in step S232, the dosage ratio of the material a, methanol, deionized water, formaldehyde solution and sulfuric acid solution is 4-6mg:30-40mL:30-40mL:15-20mL:6-8mL.
5. The process for preparing paraformaldehyde by using a spray drying method as claimed in claim 1, wherein the preparation of the catalyst comprises the following steps:
S41, mixing 1-vinylimidazole, 1, 4-dibromobutane and absolute ethyl alcohol in a nitrogen atmosphere, stirring in a water bath at 55-60 ℃ for 12-16 hours, filtering, taking a solid phase for washing, and drying to obtain a material B;
S42, mixing the material B with deionized water, stirring for 1-2h, adding lithium bistrifluoromethane sulfonyl imide, stirring for 20-24h in a water bath at 65 ℃, filtering, washing a solid phase, and vacuum drying to obtain the catalyst.
6. The process for preparing paraformaldehyde by spray drying according to claim 5, wherein in step S41, the dosage ratio of 1-vinylimidazole, 1, 4-dibromobutane, and absolute ethanol is 0.15-0.25mol:0.1 to 0.12mol:10-15mL.
7. The process for preparing paraformaldehyde by spray drying according to claim 5, wherein in step S42, the proportioning ratio of material B, deionized water and lithium bistrifluoromethane sulfonyl imide is 0.1-0.15mol:150mL:0.2-0.22mol.
8. The process for preparing paraformaldehyde by spray drying according to claim 1, wherein in step S5, the drying temperature is 55-60 ℃.
9. The process for preparing paraformaldehyde by spray drying according to claim 1, wherein in step S2, said one-stage evaporation concentration means concentration to 50-65% of the mass of the formaldehyde solution in step S1.
10. The process for preparing paraformaldehyde by using the spray drying method as claimed in claim 1, wherein in the step S3, the second-stage evaporation concentration means concentration to 75-85% of the mass of the formaldehyde solution in the step S2.
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