CN103304672A - Method and device for preparing cellulose acetate in super (sub) critical CO2 - Google Patents
Method and device for preparing cellulose acetate in super (sub) critical CO2 Download PDFInfo
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- CN103304672A CN103304672A CN2013102421180A CN201310242118A CN103304672A CN 103304672 A CN103304672 A CN 103304672A CN 2013102421180 A CN2013102421180 A CN 2013102421180A CN 201310242118 A CN201310242118 A CN 201310242118A CN 103304672 A CN103304672 A CN 103304672A
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Abstract
The invention relates to a preparation method of cellulose acetate, and particularly relates to a method and a device for preparing cellulose acetate in super (sub) critical CO2, and a device of the same. The method comprises the following steps of: generating primary cellulose acetate ester under the action of an acid catalyst by using super (sub) critical CO2 as a medium, and cotton linter and acetic anhydride as a raw material, performing super (sub) critical CO2 extraction, hydrolysis and aftertreatment on the primary cellulose acetate ester to get the cellulose acetate. In the method, high pressure CO2 is used as the medium for cellulose acetylation, the acetylation is accelerated, the acetylation in the method is solid-phase reaction, hydrolysis side reaction of the cellulose in acetylation process is limited effectively, so that the cellulose acetate product with high intrinsic viscosity can be prepared, and the production cost of cellulose acetate is lowered remarkably.
Description
Technical field
The present invention relates to the preparation method of cellulose acetate, be specifically related to a kind of super (Asia) critical CO
2Middle method and the device thereof for preparing cellulose acetate.
Background technology
Cellulose acetate is a kind of important cellulose organic ester, can be widely used as the raw materials for production of cigarette filter, plastics, film, regenerated fiber, liquid crystal protective film and coating etc., also is one of kind of output maximum in the derivatived cellulose.Usually degree of substitution with acetyl group is called cellulosetri-acetate (TCA) greater than 2.8 cellulose acetate, and substitution value is called Cellulose diacetate (DCA) between 2.0～2.7.
The industrial process of cellulose acetate mainly is solvent method, namely is acetylizing agent with the acetic anhydride, and sulfuric acid is catalyzer, and direct esterification obtains cellulose acetate in Glacial acetic acid or methylene dichloride equal solvent.The process of making cellulose acetate generally includes:
(1) cellulosic material is carried out pre-activated and handle, to improve acetylizad reactive behavior;
(2) Mierocrystalline cellulose after the activation is made cellulosetri-acetate with acetic anhydride generation acetylization reaction in Glacial acetic acid;
(3) again with the TCA hydrolysis, reduce its degree of acetylation, to obtain to be dissolved in the DCA that industrial value is more arranged in the acetone;
(4) add water DCA precipitating from reaction system is come out, again through final synthesizing and purifying DCA of operation such as bleaching, precipitating, boiling, dryings.
For example, United States Patent (USP) 3767642 discloses and a kind ofly by dilute acetic acid aqueous solution wooden oar has been carried out pre-treatment, use the acetic acid synthesized Mierocrystalline cellulose of acetic anhydride and sulfuric acid catalysis then, the cellulosetri-acetate that makes is again in 125-170 ℃ of following saponification and slaking, obtains having good transparency, the cellulose acetate of filtrability and spinning property.
United States Patent (USP) 4306060 discloses a kind of acetic acid synthesized cellulosic method.This method is at high temperature to utilize a small amount of sulfuric acid to be catalyzer, is implemented in acetylize in the short reaction times, neutralisation of sulphuric acid then, and in 110-120 ℃ of following saponification and slaking, make the cellulose acetate product.
It is the method for feedstock production cellulose acetate with the rudimentary wooden oar that contains alpha-cellulose less (85-93%) that Chinese patent ZL93106682.4 discloses a kind of.The acylating agent that this method is used the acetic acid of 400-17000 weight part and 0.1-10 weight part after crushed with the wooden oar of 100 weight parts is at 20-80 ℃ of following pre-treatment 0.5-4 hour, with optionally depolymerization hemicellulose and grape mannosans; Sulfuric acid is catalyzer then, carries out 3-20 minute acidylate with the aceticanhydride of 150-800 weight part under 50-85 ℃, and hydrolysis obtains acetyl cellulose.
Chinese patent ZL93108766.X provides a kind of method that the activation acetylize prepares cellulose acetate of uniting.This method be earlier with Mierocrystalline cellulose under amides swelling agent, fatty alcohol polyethenoxy ether class permeate agent and part glacialacetic acid and catalyst action; 28-35 ℃ of following activation treatment more than 1 hour; under 80-115 ℃, carry out acetylize with aceticanhydride then, and prepare acetyl cellulose through hydrolysis.This method can rationally be utilized heat energy, and it is low to have a catalyst levels, the characteristics that by product is few.
Chinese patent ZL99117070.9 discloses a kind of acetic ester method of gas-solid phase reaction synthetic cellulose.But this method is utilized the plain inner characteristics of acetic anhydride steam infiltrated fiber, be implemented under the comparatively high temps and produce cellulose acetate, can require under vacuum state, to carry out but react without Glacial acetic acid as reaction medium in the reaction system, be difficult to prepare the acetyl cellulose of high-polymerization degree.
The remarkable shortcoming that solvent method is in the past produced the cellulose acetate existence is that production process has a large amount of light acetums to need recycling.The cellulose acetate that forms after the Mierocrystalline cellulose acetylize and forms a uniform solution by acetic acid and solvent that acetic anhydride transforms the back by-product, for make cellulose acetate therefrom precipitating come out, need be to 3～4 times water of adding reaction mother liquor in the reaction system.In addition, in the cellulose acetate production process, carry out thoroughly in order to guarantee acetylization reaction, need to add excessive acetic anhydride.Like this, when adding depositing in water and analyse, not only cause excess acetic anhydride to recycle, also can form a large amount of dilute acetic acid solutions.The thick cellulose acetate product that precipitating is come out need further be done the boiling processing because containing a large amount of free acetic acid, to remove free acid, causes a large amount of dilute acetic acid solutions so again.The boiling point of acetic acid no matter be to adopt straight run distillation to reclaim acetic acid, still adopts extractive distillation to reclaim than water height, all can increase steam output greatly, has significantly improved the production cost of cellulose acetate.
Summary of the invention
The purpose of this invention is to provide a kind of super (Asia) critical CO
2The middle method for preparing cellulose acetate; it is the medium of Mierocrystalline cellulose acetylization reaction that this method adopts high-pressure carbon dioxide; accelerate the carrying out of acetylization reaction; acetylization reaction in this method is solid state reaction; limit Mierocrystalline cellulose effectively in the hydrolytic side reactions of acetylization reaction process; thereby produce the cellulose acetate product with high inherent viscosity, significantly reduced the production cost of cellulose acetate, the device that the present invention provides this method to use simultaneously.
Super (Asia) critical CO of the present invention
2The middle method for preparing cellulose acetate is with super (Asia) critical CO
2Being medium, is raw material with linters and acetic anhydride, prepares cellulose acetate under an acidic catalyst effect.
Specifically may further comprise the steps:
(1) pre-activated is handled: earlier linters is carried out pre-treatment with the activation solution that contains an acidic catalyst;
Containing alpha-cellulose is not less than 90% linters and at first carries out activation treatment.Activation method is very simple, and the acetum that only needs to contain an acidic catalyst that acetylize uses directly evenly is sprayed on the surface of linters, and keeps certain hour to get final product.An acidic catalyst is one or both the mixture in trifluoromethanesulfonic acid, the sulfuric acid, and the mass ratio of an acidic catalyst, linters and acetic acid is 0.01-0.05:1:0.5-2.
(2) synthetic elementary cellulose acetate: pretreated linters is at super (Asia) critical CO
2With acetic anhydride generation acetylization reaction, obtain elementary cellulose acetate in the medium;
Pretreated linters is placed in the autoclave and the acetic anhydride reaction, and suitable temperature of reaction is 30-90 ℃, and suitable working pressure is 5-30MPa, and the suitable reaction times is 0.5-5 hour.
(3) extraction: elementary cellulose acetate is surpassed (Asia) critical CO
2Extraction, the elementary cellulose acetate after reclaiming unreacted acetic anhydride and acetic acid and obtaining extracting; Extraction temperature 40-80 ℃, extracting pressure 10-30MPa.
Elementary cellulose acetate directly utilizes dynamically super (Asia) critical CO
2Unreacted aceticanhydride and acetic acid extraction residual in the product come out in extraction, and the elementary cellulose acetate after obtaining extracting in still.
The acetic anhydride that extracts and acetic acid are through decompression and CO
2Separate, reclaim and recycle.
(4) hydrolysis, neutralization: the elementary cellulose acetate after the extraction again through hydrolysis, in and an acidic catalyst obtain the secondary cellulose acetate;
Described hydrolysis, neutralization: be that the cellulose acetate after the extraction is crushed to the diameter particle less than 0.2mm, at first stir hydrolysis down at 40-90 ℃, remove an acidic catalyst with the mol ratio 1-2 that is equivalent to an acidic catalyst sodium-acetate neutralization doubly then.
(5) boiling: the secondary cellulose acetate is removed catalyzer and free acetic acid through boiling, more after filtration, oven dry makes the cellulose acetate product that substitution value is 2.0-2.95.
Described boiling: be that the secondary cellulose acetate is scattered in the aqueous systems, be heated to 90-100 ℃ and stir down, finish greater than boiling in 6 o'clock until pH value of aqueous solution.
The present invention realizes surpassing (Asia) critical CO
2The device of middle preparation cellulose acetate method comprises autoclave, autoclave and separator, compressor, CO
2Basin, high pressure CO
2Transferpump forms the loop line, wherein sets gradually stopping valve and back pressure regulating valve between autoclave and separator.
The structure of autoclave is as follows: autoclave outer setting heating jacket, heating jacket top sets out the mouth of a river, hot water inlet is offered in the bottom, the autoclave internal space is separated by the silk screen dividing plate and is divided into top linters rest area and bottom acetic anhydride rest area, the bottom of bottom acetic anhydride rest area arranges the magnetic force rotor, the magnet that the autoclave outer setting adapts with it, magnet links to each other with motor, and bottom one side of bottom acetic anhydride rest area is offered high pressure CO
2Entrance.
Compared with prior art, the present invention has following beneficial effect:
The present invention is directed to the technical problem that exists among the cellulose acetate preparation method in the past, proposed super (Asia) critical CO innovatively
2The middle acetic acid synthesized cellulosic method of the direct acetylize of Mierocrystalline cellulose.It is the reaction medium of Mierocrystalline cellulose acetylization reaction that the present invention adopts high-pressure carbon dioxide; substitute organic solvents such as previous methods acetic acid commonly used or methylene dichloride; thereby make acetylization reaction different according to temperature of reaction and pressure carbon dioxide; can under supercritical co (when temperature is higher than 31.4 ℃ and pressure greater than 7.34MPa) or subcritical carbonic acid gas (the dense gaseous carbon dioxide the when liquid carbon dioxide when comprising that temperature is lower than 31.4 ℃ and pressure greater than 7.34MPa and temperature are lower than 31.4 ℃ and pressure greater than 7.34MPa) condition, carry out.One of advantage that the employing carbonic acid gas is reaction medium is: carbonic acid gas is not only cheap and easy to get, wide material sources, and be green non-poisonous chemical.The more important thing is that the carbonic acid gas Dichlorodiphenyl Acetate Mierocrystalline cellulose under the high pressure and Mierocrystalline cellulose have good swelling ability, the carrying out that can accelerate acetylization reaction.Particularly importantly, super (Asia) critical CO
2Acetylization reaction under the condition is a kind of solid state reaction, can limit Mierocrystalline cellulose so effectively in the hydrolytic side reactions of acetylization reaction process, thereby can produce the cellulose acetate product with high inherent viscosity.
At cellulosic acetylation, the DeR of invariably accompany acetylization reaction and cellulose chain, thereby can the cellulosic polymerization degree of Dichlorodiphenyl Acetate produce remarkably influenced, show as the cellulose acetate product that is difficult to produce high inherent viscosity.For the speed of accelerating acetylization reaction and make the acetyl reaction carry out thoroughly, avoid cellulosic excessive degradation, can adopt excessive acetic anhydride usually, namely in acetic anhydride and the Mierocrystalline cellulose mol ratio of glucose unit greater than the 3:1 of theoretical value.But the consequence of bringing like this is: when after the reaction cellulose acetate being added depositing in water from reaction mother liquor and separating out, excessive acetic anhydride can be converted into acetic acid with the water reaction, can't reclaim, and has increased production cost.In addition, when being acetylizing agent with the acetic anhydride, the acetic acid of every consumption 1mol aceticanhydride meeting by-product 1mol.It is always unavoidable to produce dilture acid when adding depositing in water and analysing.Because the boiling point of acetic acid is higher than water, thus distillation to reclaim the cost of acetic acid very high.
Another outstanding advantage of method for preparing cellulose acetate provided by the invention is: behind the acetylization reaction, acetic acid excessive or unreacted acetic anhydride and association can utilize supercritical CO
2To its excellent dissolution power, by method of extraction it is separated with cellulose acetate, thereby be easy to recovery and reuse, reduced the consumption of acetic anhydride, avoided the generation of a large amount of dilture acid in the conventional art, significantly reduced cost recovery.The apparatus structure that the present invention uses is simple, processing ease.
Description of drawings
Fig. 1 is autoclave structural representation of the present invention;
Fig. 2 is the structural representation of apparatus of the present invention;
Fig. 3 is process flow diagram of the present invention;
Among the figure: 1, CO
2Outlet; 2, autoclave; 3, heating jacket; 4, silk screen dividing plate; 5, hot water inlet; 6, magnetic force rotor; 7, magnet; 8, motor; 9, high pressure CO
2Entrance; 10, bottom acetic anhydride rest area; 11, top linters rest area; 12, water outlet; 13, stopping valve; 14, back pressure regulating valve; 15, the valve between separator and the compressor; 16, separator; 17, separator bottom valve; 18, high pressure CO
2Valve between transferpump and the reactor; 19, high pressure CO
2Transferpump; 20, high pressure CO
2Transferpump and CO
2Valve between the basin; 21, CO
2Basin; 22, compressor.
Embodiment
Be described further below in conjunction with the present invention of embodiment.
The present invention prepares device that cellulose acetate uses as Figure 1-3:
Fig. 1 is autoclave 2 structural representations that the present invention uses, and the acetylization reaction of cellulose acetate is to carry out in the high pressure stainless steel cauldron shown in the accompanying drawing 1.The centre of this autoclave 2 arranges a silk screen dividing plate 4, with autoclave 2 be divided into, two portions.Top is used for placing the cellulosic material linters, and the lower section is used for placing acetic anhydride, can effectively avoid acetic anhydride directly to contact with cellulosic like this.Simultaneously, in the lower section, can place magnetic force rotor 6, with dissolving and the diffusion in the carbonic acid gas of the mass transfer of strengthening still and acetic anhydride.The shell of autoclave 2 is provided with heating jacket 3, in order to control the temperature of autoclave 2 by the water bath with thermostatic control system.Certainly, acetylization reaction also can carry out under no agitation condition, just understands because exist resistance to mass transfer, and causes acetylization reaction speed to decrease, thereby prolong the reaction times.
Fig. 2 is the apparatus structure synoptic diagram that carries out acetylization reaction and extraction under super (Asia) critical condition.Wherein, autoclave 2 and separator 16, compressor 22, CO
2Basin 21, high pressure CO
2Transferpump 19 forms the loop line, wherein sets gradually stopping valve 13 and back pressure regulating valve 14 between autoclave 2 and separator 16.
High pressure CO
2Transferpump 19 is used for to autoclave 2 interior transport of carbon dioxide continuously; Back pressure regulating valve 14 is used for the pressure of Controlling System; When 16 of separators are used for supercritical extraction, carry out CO
2Gas-liquid separation with the solute that extracts (acetic anhydride and acetic acid); The CO that compressor 22 is used for decompression
2Again CO is sent in pressurization back to
2Basin 21 is in order to recycle.Carry out acetylization reaction, at first the cellulosic material linters is positioned on the silk screen dividing plate 4 of autoclave 2, on linters, evenly spray the acetum that contains an acidic catalyst and activation certain hour then.Certainly, reactivation process also can be finished outside still.After activation finishes, with autoclave 2 good seals, with carbonic acid gas the air displacement of autoclave 2 is fallen earlier, heated up then and feed CO
2Reach the temperature and pressure of setting to the high pressure reactor 2, start stirring, keep temperature and pressure to carry out acetylization reaction.After reaction finishes, open CO
2Outlet shutoff valve 13 and CO
2Inlet valve 18 starts high pressure CO
2Transferpump 19 makes CO
2Continuous Flow is through the Mierocrystalline cellulose rest area.Regulate back pressure valve 14, make pressure-stabilisation to set(ting)value, carry out dynamic continuous extraction, make unreacted acetic anhydride and acetate dissolution in CO
2Middle extraction.CO from autoclave 2 outflows
2After decompression, enter separator 16, at this moment CO
2The dissolving power of Dichlorodiphenyl Acetate acid anhydride and acetic acid descends, and has discharged, and finishes CO in separator
2The gas-liquid separation of gas and solute.Acetic anhydride and acetic acid are stayed the bottom of separator 16, and CO
2Then flow out separator 16, and flow back to CO after the compressed supercharging
2Basin 21.
The hydrolysis purpose of cellulose acetate is to produce the cellulose acetate product with suitable degree of substitution with acetyl group, the boiling of the neutralization of catalyzer, cellulose acetate product all be the cellulose acetate preparation process the professional know knowledge.
Accompanying drawing 3 is whole process flow synoptic diagram of preparation cellulose acetate provided by the present invention.
Embodiment 1
The activation of linters: evenly spray the glacial acetic acid solution that 10mL contains 2% trifluoromethanesulfonic acid at 8.2g refined cotton linter (amount of amounting to glucose unit meter in the alpha-cellulose approximately is 50mmol, down with), and at room temperature activate 2 hours.
The preparation of cellulose acetate: the bottom at the reactor shown in the accompanying drawing 1 adds 25.5g acetic anhydride (about 250mmol); Linters after the above-mentioned activation is placed silk screen dividing plate top, behind the good seal reactor, use CO
2Cyclostrophic is changed the air in the still, heats up then and feeds CO
2To 50 ℃ and 20MPa, start magnetic agitation, stirring velocity 600 commentaries on classics/min, insulation reaction 3 hours.Reaction finishes, and opens the CO on the reactor
2Outlet valve is sent constantly into CO with high-pressure pump simultaneously
2, under 40 ℃ and 20MPa, carry out extracting operation.The CO that discharges
2Enter separator through reducing valve, collect aceticanhydride and the acetic acid of extraction, the carbonic acid gas that flows out from separator can be recycled after the compressed machine pressurization again; Be extracted to and no longer include aceticanhydride and acetic acid is come together when, stop extracting operation; Then reactor is decompressed to normal pressure, take out the elementary cellulose acetate product in the still, be crushed to particle diameter less than 0.2mm, and be scattered in the 50ml water 40 ℃ of following stirring hydrolysis 1 hour, add the 0.3g sodium-acetate then and neutralize catalyzer, again at 90-100 ℃ of boiling more than five times (each 50ml deionized water), remove the plain fluoroform acid esters of small amount of fibers and small amount of residual in the free acetic acid on cellulose acetate surface with abundant hydrolysis, refilter and oven dry makes the cellulose acetate product.Record degree of substitution with acetyl group 2.65 in the product by analysis; Be solvent with acetone, through the limiting viscosity 1.8 of capillary viscosity at 25 ℃.
The activation of linters: evenly spray the glacial acetic acid solution that 10mL contains 4% sulfuric acid at the 8.2g Mierocrystalline cellulose, and 40 ℃ of activation 2 hours.
The preparation of cellulose acetate: the bottom of reactor adds 30.6g acetic anhydride (about 300mmol), and the linters that activates is placed silk screen dividing plate top, behind the good seal reactor, uses CO
2Cyclostrophic is changed the air in the still, passes through CO
2To certain pressure, and be warmed up to 40 ℃, behind the temperature-stable, continue to feed CO
2To 30MPa, start magnetic agitation, stirring velocity 600 commentaries on classics/min, insulation reaction 5 hours.Reaction finishes, and opens CO
2Outlet valve, and constantly replenish fresh CO simultaneously
2, extract with 30MPa at 60 ℃.The CO that discharges
2Enter separator through reducing valve, collect aceticanhydride and the acetic acid of extraction, come together when until no longer including aceticanhydride and acetic acid, stop extracting operation; Be decompressed to normal pressure then, take out the cellulose acetate product in the still, be crushed to particle diameter less than 0.3mm, and be scattered in the 50ml water 60 ℃ of following stirring hydrolysis 2 hours, add the 0.5g sodium-acetate then and neutralize catalyzer, again at 90-100 ℃ of boiling more than five times (each 50ml deionized water), remove part cellulose sulfuric acid ester and small amount of residual in the free acetic acid on cellulose acetate surface with abundant hydrolysis, refilter and oven dry makes the cellulose acetate product.Record degree of substitution with acetyl group 2.76 in the product by analysis; Be solvent with acetone, through the limiting viscosity 1.3 of capillary viscosity at 25 ℃.
The activation of linters: evenly spray the acetum that 10mL contains 0.8% trifluoromethanesulfonic acid at the 8.2g Mierocrystalline cellulose, and 60 ℃ of activation 3 hours down.
The preparation of cellulose acetate: the bottom at reactor adds 40.8g acetic anhydride (about 400mmol), and the linters with activation places silk screen dividing plate top then, behind the good seal reactor, uses CO
2Cyclostrophic is changed the air in the still, passes through CO
2To certain pressure, and be warmed up to 90 ℃, behind the temperature-stable, continue to feed CO
2To 30MPa, start magnetic agitation, stirring velocity 600 commentaries on classics/min, insulation reaction 4 hours.Reaction finishes, and opens CO
2Outlet valve, and constantly replenish fresh CO simultaneously
2, extract with 30MPa at 50 ℃, come together until no longer including aceticanhydride and acetic acid.Be decompressed to normal pressure then, take out the cellulose acetate product in the still, be crushed to particle diameter less than 0.2mm, and be scattered in the 50ml water 80 ℃ of following stirring hydrolysis 1 hour, add the 0.5g sodium-acetate then and neutralize catalyzer, again at 90-100 ℃ of boiling more than five times (each 50ml deionized water), remove the fluoroform acid esters of small amount of fibers element and small amount of residual in the free acetic acid on cellulose acetate surface with abundant hydrolysis, refilter and oven dry makes the cellulose acetate product.The oven dry back obtains the cellulose acetate product, records degree of substitution with acetyl group 2.33 in the product by analysis; Be solvent with acetone, through the limiting viscosity 1.1 of capillary viscosity at 25 ℃.
The activation of linters: evenly spray the acetum that 5mL contains 3% sulfuric acid at the 8.2g Mierocrystalline cellulose, and activate 0.5 hour down at 20 ℃.
The preparation of cellulose acetate: the bottom at reactor adds 30.6g acetic anhydride (about 300mmol), and the linters with activation places silk screen dividing plate top then, behind the good seal reactor, uses CO
2Cyclostrophic is changed the air in the still, passes through CO
2To certain pressure, and be warmed up to 30 ℃, behind the temperature-stable, continue to feed CO
2To 5MPa, start magnetic agitation, stirring velocity 600 commentaries on classics/min, insulation reaction 4 hours.Reaction finishes, and opens CO
2Outlet valve, and constantly replenish fresh CO simultaneously
2, extract with 10MPa at 40 ℃.The CO that discharges
2Enter separator through reducing valve, collect aceticanhydride and the acetic acid of extraction, come together when until no longer including aceticanhydride and acetic acid, stop extracting operation; Be decompressed to normal pressure then, take out the cellulose acetate product in the still, be crushed to particle diameter less than 0.2mm, and be scattered in the 50ml water 90 ℃ of following stirring hydrolysis 3 hours, add the 0.4g sodium-acetate then and neutralize catalyzer, again at 90-100 ℃ of boiling more than five times (each 50ml deionized water), remove the sulfuric ester of small amount of fibers element and small amount of residual in the free acetic acid on cellulose acetate surface with abundant hydrolysis, refilter and oven dry makes the cellulose acetate product.The cellulose acetate product that makes after the oven dry records degree of substitution with acetyl group 2.62 in the product by analysis; Be solvent with acetone, through the limiting viscosity 1.5 of capillary viscosity at 25 ℃.
The activation of linters: evenly spray 5mL sulfur acid and trifluoromethanesulfonic acid at the 8.2g Mierocrystalline cellulose and be respectively 2% glacial acetic acid solution, and at room temperature activate 1 hour.
The preparation of cellulose acetate: the bottom at reactor adds 30.6g acetic anhydride (about 300mmol), and the linters with activation places silk screen dividing plate top then, behind the good seal reactor, uses CO
2Cyclostrophic is changed the air in the still, passes through CO
2To certain pressure, and be warmed up to 90 ℃, behind the temperature-stable, continue to feed CO
2To 25MPa, start magnetic agitation, stirring velocity 600 commentaries on classics/min, insulation reaction 3 hours.Reaction finishes, and opens CO
2Outlet valve, and constantly replenish fresh CO simultaneously
2, extract with 20MPa at 80 ℃.The CO that discharges
2Enter separator through reducing valve, collect aceticanhydride and the acetic acid of extraction, come together when until no longer including aceticanhydride and acetic acid, stop extracting operation; Be decompressed to normal pressure then, with the cellulose acetate product that takes out in the still, be decompressed to normal pressure then, take out the cellulose acetate product in the still, be crushed to particle diameter less than 0.2mm, and be scattered in the 50ml water 70 ℃ of following stirring hydrolysis 1 hour, add the 0.5g sodium-acetate then and neutralize catalyzer, again at 90-100 ℃ of boiling more than five times (each 50ml deionized water), remove part fluoroform acid esters and small amount of residual in the free acetic acid on cellulose acetate surface with abundant hydrolysis, refilter and oven dry makes the cellulose acetate product.Oven dry makes the cellulose acetate product, records degree of substitution with acetyl group 2.82 in the product by analysis; Be solvent with acetone, through the limiting viscosity 1.2 of capillary viscosity at 25 ℃.
Claims (10)
1. one kind surpasses (Asia) critical CO
2The middle method for preparing cellulose acetate is characterized in that: be with super (Asia) critical CO
2Being medium, is raw material with linters and acetic anhydride, prepares cellulose acetate under an acidic catalyst effect.
2. super (Asia) critical CO according to claim 1
2The middle method for preparing cellulose acetate, it is characterized in that: described an acidic catalyst is trifluoromethanesulfonic acid and/or sulfuric acid.
3. super (Asia) critical CO according to claim 1 and 2
2The middle method for preparing cellulose acetate, it is characterized in that: earlier linters is carried out pre-activated with the activation solution that contains an acidic catalyst before the reaction and handle, the activation solution that contains an acidic catalyst is the acetic acid that contains an acidic catalyst, and the mass ratio of an acidic catalyst, linters and acetic acid is 0.01-0.05:1:0.5-2.
4. super (Asia) critical CO according to claim 3
2The middle method for preparing cellulose acetate is characterized in that: activate pretreated linters at super (Asia) critical CO
2With acetic anhydride generation acetylization reaction, obtain elementary cellulose acetate in the medium; The acetylization reaction temperature is 30-90 ℃, and reaction pressure is 5-30MPa, and the reaction times is 0.5-5 hour.
5. super (Asia) critical CO according to claim 4
2The middle method for preparing cellulose acetate is characterized in that: elementary cellulose acetate is surpassed (Asia) critical CO
2Extraction, the elementary cellulose acetate after reclaiming unreacted acetic anhydride and acetic acid and obtaining extracting; Extraction temperature 40-80 ℃, extracting pressure 10-30MPa.
6. super (Asia) critical CO according to claim 5
2The middle method for preparing cellulose acetate is characterized in that: the acetic anhydride that extracts and acetic acid are through decompression and CO
2Separate, reclaim and recycle.
7. super (Asia) critical CO according to claim 5
2In prepare the method for cellulose acetate, it is characterized in that: the elementary cellulose acetate after the extraction again through hydrolysis, in and an acidic catalyst acquisition secondary cellulose acetate.
8. super (Asia) critical CO according to claim 7
2In prepare the method for cellulose acetate, it is characterized in that: the secondary cellulose acetate is removed catalyzer and free acetic acid through boiling, more after filtration, dry and make the cellulose acetate product that substitution value is 2.0-2.95.
9. realize super (Asia) critical CO for one kind
2The device of middle preparation cellulose acetate method comprises autoclave (2), it is characterized in that: autoclave (2) and separator (16), compressor (22), CO
2Basin (21), high pressure CO
2Transferpump (19) forms the loop line, wherein sets gradually stopping valve (13) and back pressure regulating valve (14) between autoclave (2) and separator (16).
10. realization according to claim 9 surpasses (Asia) critical CO
2The device of middle preparation cellulose acetate method, it is characterized in that: autoclave (2) outer setting heating jacket (3), heating jacket (3) top sets out the mouth of a river (12), hot water inlet (5) is offered in the bottom, autoclave (2) internal space is separated by silk screen dividing plate (4) and is divided into top linters rest area (11) and bottom acetic anhydride rest area (10), the bottom of bottom acetic anhydride rest area (10) arranges magnetic force rotor (6), the magnet (7) that autoclave (2) outer setting adapts with it, magnet (7) links to each other with motor (8), and bottom one side of bottom acetic anhydride rest area (10) is offered high pressure CO
2Entrance (9).
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN105686075A (en) * | 2016-03-08 | 2016-06-22 | 云南中烟工业有限责任公司 | Preparing method for filter tip adsorption bar made of cellulose acetate open-cell micropore foam material |
| CN106455643A (en) * | 2014-02-26 | 2017-02-22 | 伊诺威有限公司 | Super critical hydrolysis extraction apparatus and hydrolysis method using the same |
| CN111574635A (en) * | 2019-02-18 | 2020-08-25 | 四川普什醋酸纤维素有限责任公司 | Stabilization treatment system for cellulose acetate and derivatives thereof |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106455643A (en) * | 2014-02-26 | 2017-02-22 | 伊诺威有限公司 | Super critical hydrolysis extraction apparatus and hydrolysis method using the same |
| CN105686075A (en) * | 2016-03-08 | 2016-06-22 | 云南中烟工业有限责任公司 | Preparing method for filter tip adsorption bar made of cellulose acetate open-cell micropore foam material |
| CN105686075B (en) * | 2016-03-08 | 2019-08-09 | 云南中烟工业有限责任公司 | A kind of preparation method of cellulose acetate aperture microcellular foam material filter tip adsorbing bar |
| CN111574635A (en) * | 2019-02-18 | 2020-08-25 | 四川普什醋酸纤维素有限责任公司 | Stabilization treatment system for cellulose acetate and derivatives thereof |
| CN111574635B (en) * | 2019-02-18 | 2022-05-20 | 四川普什醋酸纤维素有限责任公司 | Stabilization treatment system for cellulose acetate and derivatives thereof |
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| CN103304672B (en) | 2015-06-10 |
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