CN103145578B - Preparation and purification method of methacrylamide - Google Patents
Preparation and purification method of methacrylamide Download PDFInfo
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- CN103145578B CN103145578B CN201310104340.4A CN201310104340A CN103145578B CN 103145578 B CN103145578 B CN 103145578B CN 201310104340 A CN201310104340 A CN 201310104340A CN 103145578 B CN103145578 B CN 103145578B
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Abstract
The invention discloses a preparation and purification method of methacrylamide. The method comprises the following steps: hydrolyzing and dehydrating by concentrated sulfuric acid to generate methacrylamide sulfate based on acetone cyanohydrin as a main raw material; neutralizing the methacrylamide sulfate by ammonia gas or ammonia water; circularly applying the neutralized centrifuged mother liquor; and purifying the methacrylamide crude product containing ammonium sulfate by sublimating, thereby obtaining the pure methacrylamide. According to the process, the mother liquor can be circularly applied so as to greatly reduce the discharge of salt-containing acid-containing sewage and avoid the environment pollution, reduce the dissolving of the methacrylamide in the mother liquor and improve the yield of the methacrylamide; and the purity of the obtained pure methacrylamide can be more than 99%, and the yield is more than 90%.
Description
Technical field
The present invention relates to the synthesis technical field of Methacrylamide, particularly a kind of preparation of Methacrylamide and method of purification.
Background technology
Methacrylic acid amino is mainly used in silk weighting agent, fiber levelling agent, moisture adsorbent, tackiness agent and static inhibitor, also as cement additire, grout additive, leatheroid additive etc.The quality of Methacrylamide is decided by the rate of body weight gain of Methacrylamide in silk weighting process, and producing Methacrylamide has methacrylic eyeball hydrolysis method, acetone cyanohydrin sour water solution, methyl methacrylate ammonolysis process and methacrylic acid and ammonia synthesis.Industrial main employing acetone cyanohydrin hydrolysis method, domesticly still rests on the lab scale stage at present, and product purity reaches 95%, and productive rate often only has 60%～70% left and right.Operational path is in the past produced Methacrylamide (comprising methyl methacrylate and methacrylic acid) can produce a large amount of waste water, owing to containing a certain amount of Methacrylamide and methacrylic acid in waste water, along with the waste water shelf-time is long, in waste water, produce a large amount of polymkeric substance, the discharge of waste water, to environment, is also a kind of loss to product.
Summary of the invention
In view of this, the invention provides a kind of preparation and method of purification of Methacrylamide, can greatly reduce the discharge of saliferous acid-bearing wastewater, and improve the productive rate of Methacrylamide.
The preparation of Methacrylamide of the present invention and method of purification, comprise the following steps:
1) acetone cyanohydrin and vitriol oil effect, hydrolysis generates α-formamido-sec.-propyl hydrogen sulfuric acid ester;
2) α-formamido-sec.-propyl hydrogen sulfuric acid ester is under vitriol oil effect, and dehydration generates methacrylamide sulfate;
3) with ammonia or ammonia neutralization methacrylamide sulfate, make its sulfuric acid be converted into ammonium sulfate completely;
4) neutralization after, crystallisation by cooling, centrifugal go out crystal, Recycling Mother Solution get back to step 3) in and system in be used as solvent, the Methacrylamide wet product that crystal is liquid containing ammonium sulfate;
5) the Methacrylamide wet product of liquid containing ammonium sulfate is dried, obtain the Methacrylamide crude product of liquid containing ammonium sulfate, the Methacrylamide crude product of liquid containing ammonium sulfate is purified through distillation, obtains Methacrylamide sterling.
The reaction formula of described step 1) is:
Its preferred processing parameter is: the mass ratio of acetone cyanohydrin and the vitriol oil is 1:1.1～1.6, and the mass concentration of the vitriol oil is 98%～100.3%, and acetone cyanohydrin and the vitriol oil take two modes that drip to add reaction system, and temperature of reaction is 60 DEG C～100 DEG C; In reaction system, can add stopper, stopper is one or several of Resorcinol, thiodiphenylamine and copper sulfate, and the quality of stopper is acetone cyanohydrin 0.1%～0.5%.
Described step 2) reaction formula be:
Its preferred processing parameter is: temperature of reaction is 100 DEG C～150 DEG C.
The reaction formula of described step 3) is:
Its preferred processing parameter is: in dropping to after methacrylamide sulfate is cooled to 90 DEG C～100 DEG C and in system, simultaneously toward in system in pass into ammoniacal liquor or ammonia, temperature of reaction is 0 DEG C～60 DEG C, after neutralization in and the pH value of system be 5.5～7.0.
The preferred processing parameter of described step 4) is: Tc is 0 DEG C～25 DEG C.
The preferred processing parameter of described step 5) is: bake out temperature is 40 DEG C～60 DEG C, and the water content of the Methacrylamide crude product of liquid containing ammonium sulfate is controlled in 2%, and sublimation temperature is 100 DEG C～160 DEG C.
In described step 3), for the first time in and time, in and the solvent of system be water, 3～5 times of the quality that the quality of water is ammonia; Second and later time in and time, in and the solvent of system be the mother liquor of step 4) cyclically utilizing.
Beneficial effect of the present invention is: the present invention is taking acetone cyanohydrin as main raw material, through effects such as vitriol oil hydrolysis, dehydrations, generate methacrylamide sulfate, methacrylamide sulfate is through ammonia or ammonia neutralization, centrifuge mother liquor recycled after neutralization, and the Methacrylamide crude product of liquid containing ammonium sulfate is purified and is obtained Methacrylamide sterling through distillation.The present invention adopts new operational path, make the mother liquor can recycled, thereby greatly reduce the discharge of saliferous acid-bearing wastewater, avoid the pollution of waste water to environment, and reduce the dissolving of Methacrylamide in mother liquor, improve the productive rate of Methacrylamide, more than Methacrylamide sterling purity 99 % that obtain, more than productive rate can reach 90 %.
The present invention is a kind of less energy-consumption, eco-friendly, the operational path that reduces production costs, reduce investment, is specially adapted to industrial scale, serialization is produced, and especially reduces discharge of wastewater, increases output successful.
Brief description of the drawings
In order to make the object, technical solutions and advantages of the present invention clearer, below in conjunction with accompanying drawing, the present invention is described in further detail, wherein:
Fig. 1 is process flow sheet of the present invention.
Embodiment
Hereinafter with reference to accompanying drawing, the preferred embodiments of the present invention are described in detail.
embodiment 1
1) by the vitriol oil (1360 kilograms), acetone cyanohydrin (850 kilograms) process spinner-type flowmeter, according to 1.6:1(mass ratio) ratio drops in reactor, acetone cyanohydrin and vitriol oil effect, hydrolysis generates α-formamido-sec.-propyl hydrogen sulfuric acid ester, because reaction is now thermopositive reaction, so open cooling system, make a pot interior reaction temperature remain on 90 DEG C, resultant overflows from reactor overflow port, enters tubular reactor;
2) above-mentioned reactant continues and vitriol oil generation chemical reaction in tubular reactor, α-formamido-sec.-propyl hydrogen sulfuric acid ester is under vitriol oil effect, dehydration generates methacrylamide sulfate, this reaction is thermo-negative reaction, with being steam heated to 135 DEG C, because temperature is too low, chemical reaction is incomplete, excess Temperature, easily causes polymerization or charing, is key factor so control temperature; For reaction is tending towards completely, resultant enters warmer, and holding temperature is controlled at 130 DEG C of left and right; When material proceeds to after acid amides susceptor, sampling analysis, the content of its Methacrylamide is more than 34%, the productive rate of Methacrylamide is 97%;
3) above-mentioned methacrylamide sulfate is cooled to 100 DEG C, keeps the mobility of methacrylamide sulfate; In and in still, add 1632 kilograms, water, be cooled to 10 DEG C, then slowly drip methacrylamide sulfate, pass into ammonia simultaneously, pass into the total amount of ammonia with sulphur acid meter, just completely neutralisation of sulphuric acid is converted into ammonium sulfate and is advisable; Because neutralization reaction is thermopositive reaction, in and still inner coil pipe pass into water of condensation, control temperature of reaction be no more than 60 DEG C, excess Temperature, can there is hydrolysis reaction in Methacrylamide;
4) neutralization after, be cooled to 10 DEG C of left and right, crystal is separated out completely, then centrifugal, the Methacrylamide wet product that crystal is liquid containing ammonium sulfate obtains 1805 kilograms, mother liquor, mother liquor be circulated back to next time step 3) in and system in be used as solvent;
5) by the Methacrylamide wet product vacuum drying of liquid containing ammonium sulfate, control water content in 2%, obtain 2507 kilograms of Methacrylamide crude products, crude product is dropped in distillation still, and the purification that distils, obtains 773 kilograms of Methacrylamide sterlings, content is 99%, and yield is 90%.
embodiment 2(Recycling Mother Solution applies mechanically 1)
1) by the vitriol oil (1360 kilograms), acetone cyanohydrin (850 kilograms) process spinner-type flowmeter, according to 1.6:1(mass ratio) ratio drops in reactor, acetone cyanohydrin and vitriol oil effect, hydrolysis generates α-formamido-sec.-propyl hydrogen sulfuric acid ester, because reaction is now thermopositive reaction, so open cooling system, make a pot interior reaction temperature remain on 90 DEG C, resultant overflows from reactor overflow port, enters tubular reactor;
2) above-mentioned reactant continues and vitriol oil generation chemical reaction in tubular reactor, α-formamido-sec.-propyl hydrogen sulfuric acid ester is under vitriol oil effect, dehydration generates methacrylamide sulfate, this reaction is thermo-negative reaction, with being steam heated to 135 DEG C, because temperature is too low, chemical reaction is incomplete, excess Temperature, easily causes polymerization or charing, is key factor so control temperature; For reaction is tending towards completely, resultant enters warmer, and holding temperature is controlled at 130 DEG C of left and right; When material proceeds to after acid amides susceptor, sampling analysis, the content of its Methacrylamide is more than 34%, the productive rate of Methacrylamide is 97%;
3) above-mentioned methacrylamide sulfate is cooled to 100 DEG C, keeps the mobility of methacrylamide sulfate; In and in still, add 1805 kilograms, the mother liquor of embodiment 1 gained, be cooled to 10 DEG C, then slowly drip methacrylamide sulfate, pass into ammonia simultaneously, pass into the total amount of ammonia with sulphur acid meter, neutralisation of sulphuric acid is converted into ammonium sulfate and is advisable completely just; Because neutralization reaction is thermopositive reaction, in and still inner coil pipe pass into water of condensation, control temperature of reaction be no more than 60 DEG C, excess Temperature, can there is hydrolysis reaction in Methacrylamide;
4) neutralization after, be cooled to 10 DEG C of left and right, crystal is separated out completely, then centrifugal, the Methacrylamide wet product that crystal is liquid containing ammonium sulfate obtains 2098 kilograms, mother liquor, mother liquor be circulated back to next time step 3) in and system in be used as solvent;
5) by the Methacrylamide wet product vacuum drying of liquid containing ammonium sulfate, control water content in 2%, obtain 2397 kilograms of Methacrylamide crude products, crude product is dropped in distillation still, and the purification that distils, obtains 790 kilograms of Methacrylamide sterlings, content is 99.1%, and yield is 92%.
embodiment 3(Recycling Mother Solution applies mechanically 2)
1) by the vitriol oil (1360 kilograms), acetone cyanohydrin (850 kilograms) process spinner-type flowmeter, according to 1.6:1(mass ratio) ratio drops in reactor, acetone cyanohydrin and vitriol oil effect, hydrolysis generates α-formamido-sec.-propyl hydrogen sulfuric acid ester, because reaction is now thermopositive reaction, so open cooling system, make a pot interior reaction temperature remain on 90 DEG C, resultant overflows from reactor overflow port, enters tubular reactor;
2) above-mentioned reactant continues and vitriol oil generation chemical reaction in tubular reactor, α-formamido-sec.-propyl hydrogen sulfuric acid ester is under vitriol oil effect, dehydration generates methacrylamide sulfate, this reaction is thermo-negative reaction, with being steam heated to 135 DEG C, because temperature is too low, chemical reaction is incomplete, excess Temperature, easily causes polymerization or charing, is key factor so control temperature; For reaction is tending towards completely, resultant enters warmer, and holding temperature is controlled at 130 DEG C of left and right; When material proceeds to after acid amides susceptor, sampling analysis, the content of its Methacrylamide is more than 34%, the productive rate of Methacrylamide is 97%;
3) above-mentioned methacrylamide sulfate is cooled to 100 DEG C, keeps the mobility of methacrylamide sulfate; In and in still, add 2098 kilograms, the mother liquor of embodiment 2 gained, be cooled to 10 DEG C, then slowly drip methacrylamide sulfate, pass into ammonia simultaneously, pass into the total amount of ammonia with sulphur acid meter, neutralisation of sulphuric acid is converted into ammonium sulfate and is advisable completely just; Because neutralization reaction is thermopositive reaction, in and still inner coil pipe pass into water of condensation, control temperature of reaction be no more than 60 DEG C, excess Temperature, can there is hydrolysis reaction in Methacrylamide;
4) neutralization after, be cooled to 10 DEG C of left and right, crystal is separated out completely, then centrifugal, the Methacrylamide wet product that crystal is liquid containing ammonium sulfate obtains 1798 kilograms, mother liquor, mother liquor be circulated back to next time step 3) in and system in be used as solvent;
5) by the Methacrylamide wet product vacuum drying of liquid containing ammonium sulfate, control water content in 2%, obtain 2990 kilograms of Methacrylamide crude products, crude product is dropped in distillation still, and the purification that distils, obtains 792 kilograms of Methacrylamide sterlings, content is 99.1%, and yield is 92%.
embodiment 4(Recycling Mother Solution applies mechanically 3)
1) by the vitriol oil (1360 kilograms), acetone cyanohydrin (850 kilograms) process spinner-type flowmeter, according to 1.6:1(mass ratio) ratio drops in reactor, acetone cyanohydrin and vitriol oil effect, hydrolysis generates α-formamido-sec.-propyl hydrogen sulfuric acid ester, because reaction is now thermopositive reaction, so open cooling system, make a pot interior reaction temperature remain on 90 DEG C, resultant overflows from reactor overflow port, enters tubular reactor;
2) above-mentioned reactant continues and vitriol oil generation chemical reaction in tubular reactor, α-formamido-sec.-propyl hydrogen sulfuric acid ester is under vitriol oil effect, dehydration generates methacrylamide sulfate, this reaction is thermo-negative reaction, with being steam heated to 135 DEG C, because temperature is too low, chemical reaction is incomplete, excess Temperature, easily causes polymerization or charing, is key factor so control temperature; For reaction is tending towards completely, resultant enters warmer, and holding temperature is controlled at 130 DEG C of left and right; When material proceeds to after acid amides susceptor, sampling analysis, the content of its Methacrylamide is more than 34%, the productive rate of Methacrylamide is 97%;
3) above-mentioned methacrylamide sulfate is cooled to 100 DEG C, keeps the mobility of methacrylamide sulfate; In and in still, add 1798 kilograms, the mother liquor of embodiment 3 gained, add 100 kilograms, water, be cooled to 10 DEG C, then slowly drip methacrylamide sulfate, pass into ammonia simultaneously, pass into the total amount of ammonia with sulphur acid meter, just complete neutralisation of sulphuric acid is converted into ammonium sulfate and is advisable; Because neutralization reaction is thermopositive reaction, in and still inner coil pipe pass into water of condensation, control temperature of reaction be no more than 60 DEG C, excess Temperature, can there is hydrolysis reaction in Methacrylamide;
4) neutralization after, be cooled to 10 DEG C of left and right, crystal is separated out completely, then centrifugal, the Methacrylamide wet product that crystal is liquid containing ammonium sulfate obtains 1870 kilograms, mother liquor, mother liquor be circulated back to next time step 3) in and system in be used as solvent;
5) by the Methacrylamide wet product vacuum drying of liquid containing ammonium sulfate, control water content in 2%, obtain 2790 kilograms of Methacrylamide crude products, crude product is dropped in distillation still, and the purification that distils, obtains 852 kilograms of Methacrylamide sterlings, content is 99%, and yield is 100.2%.
embodiment 5(Recycling Mother Solution applies mechanically 4)
1) by the vitriol oil (1360 kilograms), acetone cyanohydrin (850 kilograms) process spinner-type flowmeter, according to 1.6:1(mass ratio) ratio drops in reactor, acetone cyanohydrin and vitriol oil effect, hydrolysis generates α-formamido-sec.-propyl hydrogen sulfuric acid ester, because reaction is now thermopositive reaction, so open cooling system, make a pot interior reaction temperature remain on 90 DEG C, resultant overflows from reactor overflow port, enters tubular reactor;
2) above-mentioned reactant continues and vitriol oil generation chemical reaction in tubular reactor, α-formamido-sec.-propyl hydrogen sulfuric acid ester is under vitriol oil effect, dehydration generates methacrylamide sulfate, this reaction is thermo-negative reaction, with being steam heated to 135 DEG C, because temperature is too low, chemical reaction is incomplete, excess Temperature, easily causes polymerization or charing, is key factor so control temperature; For reaction is tending towards completely, resultant enters warmer, and holding temperature is controlled at 130 DEG C of left and right; When material proceeds to after acid amides susceptor, sampling analysis, the content of its Methacrylamide is more than 34%, the productive rate of Methacrylamide is 97%;
3) above-mentioned methacrylamide sulfate is cooled to 100 DEG C, keeps the mobility of methacrylamide sulfate; In and in still, add 1870 kilograms, the mother liquor of embodiment 4 gained, be cooled to 10 DEG C, then slowly drip methacrylamide sulfate, pass into ammonia simultaneously, pass into the total amount of ammonia with sulphur acid meter, neutralisation of sulphuric acid is converted into ammonium sulfate and is advisable completely just; Because neutralization reaction is thermopositive reaction, in and still inner coil pipe pass into water of condensation, control temperature of reaction be no more than 60 DEG C, excess Temperature, can there is hydrolysis reaction in Methacrylamide;
4) neutralization after, be cooled to 10 DEG C of left and right, crystal is separated out completely, then centrifugal, the Methacrylamide wet product that crystal is liquid containing ammonium sulfate obtains 1760 kilograms, mother liquor, mother liquor be circulated back to next time step 3) in and system in be used as solvent;
5) by the Methacrylamide wet product vacuum drying of liquid containing ammonium sulfate, control water content in 2%, obtain 2968 kilograms of Methacrylamide crude products, crude product is dropped in distillation still, and the purification that distils, obtains 841 kilograms of Methacrylamide sterlings, content is 99%, and yield is 98%.
embodiment 6(Recycling Mother Solution applies mechanically 5)
1) by the vitriol oil (1360 kilograms), acetone cyanohydrin (850 kilograms) process spinner-type flowmeter, according to 1.6:1(mass ratio) ratio drops in reactor, acetone cyanohydrin and vitriol oil effect, hydrolysis generates α-formamido-sec.-propyl hydrogen sulfuric acid ester, because reaction is now thermopositive reaction, so open cooling system, make a pot interior reaction temperature remain on 90 DEG C, resultant overflows from reactor overflow port, enters tubular reactor;
2) above-mentioned reactant continues and vitriol oil generation chemical reaction in tubular reactor, α-formamido-sec.-propyl hydrogen sulfuric acid ester is under vitriol oil effect, dehydration generates methacrylamide sulfate, this reaction is thermo-negative reaction, with being steam heated to 135 DEG C, because temperature is too low, chemical reaction is incomplete, excess Temperature, easily causes polymerization or charing, is key factor so control temperature; For reaction is tending towards completely, resultant enters warmer, and holding temperature is controlled at 130 DEG C of left and right; When material proceeds to after acid amides susceptor, sampling analysis, the content of its Methacrylamide is more than 34%, the productive rate of Methacrylamide is 97%;
3) above-mentioned methacrylamide sulfate is cooled to 100 DEG C, keeps the mobility of methacrylamide sulfate; In and in still, add 1760 kilograms, the mother liquor of embodiment 5 gained, be cooled to 10 DEG C, then slowly drip methacrylamide sulfate, pass into ammonia simultaneously, pass into the total amount of ammonia with sulphur acid meter, neutralisation of sulphuric acid is converted into ammonium sulfate and is advisable completely just; Because neutralization reaction is thermopositive reaction, in and still inner coil pipe pass into water of condensation, control temperature of reaction be no more than 60 DEG C, excess Temperature, can there is hydrolysis reaction in Methacrylamide;
4) neutralization after, be cooled to 10 DEG C of left and right, crystal is separated out completely, then centrifugal, the Methacrylamide wet product that crystal is liquid containing ammonium sulfate obtains 1850 kilograms, mother liquor, mother liquor be circulated back to next time step 3) in and system in be used as solvent;
5) by the Methacrylamide wet product vacuum drying of liquid containing ammonium sulfate, control water content in 2%, obtain 2668 kilograms of Methacrylamide crude products, crude product is dropped in distillation still, and the purification that distils, obtains 810 kilograms of Methacrylamide sterlings, content is 99%, and yield is 95%.
embodiment 7(Recycling Mother Solution applies mechanically 6)
1) by the vitriol oil (1360 kilograms), acetone cyanohydrin (850 kilograms) process spinner-type flowmeter, according to 1.6:1(mass ratio) ratio drops in reactor, acetone cyanohydrin and vitriol oil effect, hydrolysis generates α-formamido-sec.-propyl hydrogen sulfuric acid ester, because reaction is now thermopositive reaction, so open cooling system, make a pot interior reaction temperature remain on 90 DEG C, resultant overflows from reactor overflow port, enters tubular reactor;
2) above-mentioned reactant continues and vitriol oil generation chemical reaction in tubular reactor, α-formamido-sec.-propyl hydrogen sulfuric acid ester is under vitriol oil effect, dehydration generates methacrylamide sulfate, this reaction is thermo-negative reaction, with being steam heated to 135 DEG C, because temperature is too low, chemical reaction is incomplete, excess Temperature, easily causes polymerization or charing, is key factor so control temperature; For reaction is tending towards completely, resultant enters warmer, and holding temperature is controlled at 130 DEG C of left and right; When material proceeds to after acid amides susceptor, sampling analysis, the content of its Methacrylamide is more than 34%, the productive rate of Methacrylamide is 97%;
3) above-mentioned methacrylamide sulfate is cooled to 100 DEG C, keeps the mobility of methacrylamide sulfate; In and in still, add 1850 kilograms, the mother liquor of embodiment 6 gained, be cooled to 10 DEG C, then slowly drip methacrylamide sulfate, pass into ammonia simultaneously, pass into the total amount of ammonia with sulphur acid meter, neutralisation of sulphuric acid is converted into ammonium sulfate and is advisable completely just; Because neutralization reaction is thermopositive reaction, in and still inner coil pipe pass into water of condensation, control temperature of reaction be no more than 60 DEG C, excess Temperature, can there is hydrolysis reaction in Methacrylamide;
4) neutralization after, be cooled to 10 DEG C of left and right, crystal is separated out completely, then centrifugal, the Methacrylamide wet product that crystal is liquid containing ammonium sulfate obtains 2090 kilograms, mother liquor, mother liquor be circulated back to next time step 3) in and system in be used as solvent;
5) by the Methacrylamide wet product vacuum drying of liquid containing ammonium sulfate, control water content in 2%, obtain 2368 kilograms of Methacrylamide crude products, crude product is dropped in distillation still, and the purification that distils, obtains 790 kilograms of Methacrylamide sterlings, content is 99%, and yield is 92%.
embodiment 8(Recycling Mother Solution applies mechanically 7)
1) by the vitriol oil (1360 kilograms), acetone cyanohydrin (850 kilograms) process spinner-type flowmeter, according to 1.6:1(mass ratio) ratio drops in reactor, acetone cyanohydrin and vitriol oil effect, hydrolysis generates α-formamido-sec.-propyl hydrogen sulfuric acid ester, because reaction is now thermopositive reaction, so open cooling system, make a pot interior reaction temperature remain on 90 DEG C, resultant overflows from reactor overflow port, enters tubular reactor;
2) above-mentioned reactant continues and vitriol oil generation chemical reaction in tubular reactor, α-formamido-sec.-propyl hydrogen sulfuric acid ester is under vitriol oil effect, dehydration generates methacrylamide sulfate, this reaction is thermo-negative reaction, with being steam heated to 135 DEG C, because temperature is too low, chemical reaction is incomplete, excess Temperature, easily causes polymerization or charing, is key factor so control temperature; For reaction is tending towards completely, resultant enters warmer, and holding temperature is controlled at 130 DEG C of left and right; When material proceeds to after acid amides susceptor, sampling analysis, the content of its Methacrylamide is more than 34%, the productive rate of Methacrylamide is 97%;
3) above-mentioned methacrylamide sulfate is cooled to 100 DEG C, keeps the mobility of methacrylamide sulfate; In and in still, add 2090 kilograms, the mother liquor of embodiment 7 gained, be cooled to 10 DEG C, then slowly drip methacrylamide sulfate, pass into ammonia simultaneously, pass into the total amount of ammonia with sulphur acid meter, neutralisation of sulphuric acid is converted into ammonium sulfate and is advisable completely just; Because neutralization reaction is thermopositive reaction, in and still inner coil pipe pass into water of condensation, control temperature of reaction be no more than 60 DEG C, excess Temperature, can there is hydrolysis reaction in Methacrylamide;
4) neutralization after, be cooled to 10 DEG C of left and right, crystal is separated out completely, then centrifugal, the Methacrylamide wet product that crystal is liquid containing ammonium sulfate obtains 2100 kilograms, mother liquor, mother liquor be circulated back to next time step 3) in and system in be used as solvent;
5) by the Methacrylamide wet product vacuum drying of liquid containing ammonium sulfate, control water content in 2%, obtain 1953 kilograms of Methacrylamide crude products, crude product is dropped in distillation still, and the purification that distils, obtains 781 kilograms of Methacrylamide sterlings, content is 99%, and yield is 91%.
embodiment 9(Recycling Mother Solution applies mechanically 8)
1) by the vitriol oil (1360 kilograms), acetone cyanohydrin (850 kilograms) process spinner-type flowmeter, according to 1.6:1(mass ratio) ratio drops in reactor, acetone cyanohydrin and vitriol oil effect, hydrolysis generates α-formamido-sec.-propyl hydrogen sulfuric acid ester, because reaction is now thermopositive reaction, so open cooling system, make a pot interior reaction temperature remain on 90 DEG C, resultant overflows from reactor overflow port, enters tubular reactor;
2) above-mentioned reactant continues and vitriol oil generation chemical reaction in tubular reactor, α-formamido-sec.-propyl hydrogen sulfuric acid ester is under vitriol oil effect, dehydration generates methacrylamide sulfate, this reaction is thermo-negative reaction, with being steam heated to 135 DEG C, because temperature is too low, chemical reaction is incomplete, excess Temperature, easily causes polymerization or charing, is key factor so control temperature; For reaction is tending towards completely, resultant enters warmer, and holding temperature is controlled at 130 DEG C of left and right; When material proceeds to after acid amides susceptor, sampling analysis, the content of its Methacrylamide is more than 34%, the productive rate of Methacrylamide is 97%;
3) above-mentioned methacrylamide sulfate is cooled to 100 DEG C, keeps the mobility of methacrylamide sulfate; In and in still, add 2100 kilograms, the mother liquor of embodiment 8 gained, be cooled to 10 DEG C, then slowly drip methacrylamide sulfate, pass into ammonia simultaneously, pass into the total amount of ammonia with sulphur acid meter, neutralisation of sulphuric acid is converted into ammonium sulfate and is advisable completely just; Because neutralization reaction is thermopositive reaction, in and still inner coil pipe pass into water of condensation, control temperature of reaction be no more than 60 DEG C, excess Temperature, can there is hydrolysis reaction in Methacrylamide;
4) neutralization after, be cooled to 10 DEG C of left and right, crystal is separated out completely, then centrifugal, the Methacrylamide wet product that crystal is liquid containing ammonium sulfate obtains 2030 kilograms, mother liquor, mother liquor be circulated back to next time step 3) in and system in be used as solvent;
5) by the Methacrylamide wet product vacuum drying of liquid containing ammonium sulfate, control water content in 2%, obtain 2035 kilograms of Methacrylamide crude products, crude product is dropped in distillation still, and the purification that distils, obtains 773 kilograms of Methacrylamide sterlings, content is 99%, and yield is 90%.
For the first time and time, in and the solvent of system be water, 3～5 times of the quality that the quality of water is ammonia; Second and later time in and time, in and the solvent of system be the mother liquor of step 4) cyclically utilizing; In case of no particular description, mother liquor is that recycled goes down completely, the number of times of applying mechanically is not limited to above-mentioned number of times, mother liquor is along with the number of times of applying mechanically increases, the water yield can reduce to some extent, in order to guarantee neutralization stirring fully, can suitably in mother liquor, add water, the water yield of adding is can make system fully stir and be as the criterion.In and when methacrylamide sulfate, preferably ammonia; As used ammonia neutralization, mother liquor, for cover used time next time, needs the amount of extraction 30%～50%.
Finally explanation is, above embodiment is only unrestricted in order to technical scheme of the present invention to be described, although by with reference to the preferred embodiments of the present invention, invention has been described, but those of ordinary skill in the art is to be understood that, can make various changes to it in the form and details, and not depart from the spirit and scope of the present invention that appended claims limits.
Claims (6)
1. a preparation method for Methacrylamide, is characterized in that: comprise the following steps:
1) acetone cyanohydrin and vitriol oil effect, hydrolysis generates α-formamido-sec.-propyl hydrogen sulfuric acid ester;
2) α-formamido-sec.-propyl hydrogen sulfuric acid ester is under vitriol oil effect, and dehydration generates methacrylamide sulfate;
3) with ammonia or ammonia neutralization methacrylamide sulfate, make its sulfuric acid be converted into ammonium sulfate completely; Concrete operations are in dropping to after methacrylamide sulfate is cooled to 90 DEG C～100 DEG C and in system, simultaneously toward in and in system, pass into ammoniacal liquor or ammonia, temperature of reaction is 0 DEG C～60 DEG C, after neutralization in the pH value of system be 5.5～7.0;
4) neutralization after, crystallisation by cooling, centrifugal go out crystal, Recycling Mother Solution get back to step 3) in and system in be used as solvent, the Methacrylamide wet product that crystal is liquid containing ammonium sulfate;
5) the Methacrylamide wet product of liquid containing ammonium sulfate is dried, obtain the Methacrylamide crude product of liquid containing ammonium sulfate, the Methacrylamide crude product of liquid containing ammonium sulfate is purified through distillation, obtains Methacrylamide sterling;
In described step 3), for the first time in and time, in and the solvent of system be water, 3～5 times of the quality that the quality of water is ammonia; Second and later time in and time, in and the solvent of system be the mother liquor of step 4) cyclically utilizing.
2. the preparation method of Methacrylamide according to claim 1, it is characterized in that: in described step 1), the mass ratio of acetone cyanohydrin and the vitriol oil is 1:1.1～1.6, the mass concentration of the vitriol oil is 98%～100.3%, acetone cyanohydrin and the vitriol oil take two modes that drip to add reaction system, and temperature of reaction is 60 DEG C～100 DEG C.
3. the preparation method of Methacrylamide according to claim 1, it is characterized in that: in described step 1), in reaction system, add and have stopper, stopper is one or several of Resorcinol, thiodiphenylamine and copper sulfate, and the quality of stopper is acetone cyanohydrin 0.1%～0.5%.
4. the preparation method of Methacrylamide according to claim 1, is characterized in that: described step 2) in, temperature of reaction is 100 DEG C～150 DEG C.
5. the preparation method of Methacrylamide according to claim 1, is characterized in that: in described step 4), Tc is 0 DEG C～25 DEG C.
6. the preparation method of Methacrylamide according to claim 1, it is characterized in that: in described step 5), bake out temperature is 40 DEG C～60 DEG C, and the water content of the Methacrylamide crude product of liquid containing ammonium sulfate is controlled in 2%, and sublimation temperature is 100 DEG C～160 DEG C.
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| CN1712393A (en) * | 2004-06-22 | 2005-12-28 | 上海制笔化工厂 | Production of methacrylic acid |
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| 甲基丙烯酰胺合成工艺的改进;胡华;《江苏化工》;19971031;第25卷(第5期);第26-27页 * |
| 胡华.甲基丙烯酰胺合成工艺的改进.《江苏化工》.1997,第25卷(第5期),第26-27页. |
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