CN1821210A - Processes for producing (meth)acrylic acid compound - Google Patents

Abstract

A method of recovering methacrylic acid ester by pyrolyzing, e.g., a by-product of the Michael addition reaction in a step for methacrylic acid ester production. It attains a high recovery and diminish by-product ethers. The method is characterized in that the pyrolysis of a by-product generated in a step for methacrylic acid ester production is conducted substantially in a liquid phase and at least 50% of the product of the pyrolysis is returned to an upstream step. The method in which the by-product is decomposed in the presence of an acid catalyst is characterized by adding the acid catalyst in an amount of 0.1 to 1.0 wt.% based on the by-product.

Description

The method of preparation (methyl) acrylic compound

The application is to be on November 26th, 2002 applying date, and national applications number is 02822870.7, is entitled as dividing an application of " method of preparation (methyl) acrylic compound " international application (PCT/JP02/12332).

Technical field

First and second aspects of the present invention relate separately to the method for a kind of preparation (methyl) acrylic compound and the method for a kind of preparation (methyl) acrylate.Particularly, a second aspect of the present invention relates to the method for a kind of preparation (methyl) acrylate, and this method comprises the by-product destruction with the formation reaction of (methyl) acrylate, with the step that reclaims (methyl) acrylate etc.

A third aspect of the present invention relates to the method for the by product of a kind of decomposition (methyl) acrylate production, so that by decomposing the by product that (methyl) acrylate is produced, reclaim (methyl) vinylformic acid, (methyl) acrylate, alcohol etc.

The the of the present invention the 4th and the 5th aspect relates to the method for the by product of a kind of decomposition (methyl) acrylic compound production, so that the by product by by product and (methyl) acrylate of the production of decomposition (methyl) vinylformic acid are produced reclaims (methyl) vinylformic acid, (methyl) acrylate, alcohol etc.

Incidentally, term in this specification sheets (methyl) vinylformic acid is the general designation of vinylformic acid and methacrylic acid, and it can be in vinylformic acid and the methacrylic acid any one, also can be the two.And term (methyl) acrylic compound is vinylformic acid and methacrylic acid and the general designation that derives from these acid and alcohol (methyl) acrylate, and means wherein at least a.

Background technology

As everyone knows, generate the gas phase oxidation that the acrylic acid reaction be used to produce acrylate comprises propylene.This propylene oxide comprises two-step oxidation technology to obtain acrylic acid, wherein to propenal and carrying out in different reactors because of reaction conditions is different subsequently, and by the raw material direct oxidation to acrylic acid oxidation to acrylic acid oxidation step technology.

Fig. 2 is the example of process flow sheet, and wherein vinylformic acid generates by the two-step oxidation reaction, and by further generating acrylate with the alcohol reaction.Propylene, water vapor and air be by being filled with first reactor and second reactor of molybdenum catalyst etc., and then make propylene oxidation in two steps, obtains containing acrylic acid gas.Make this contain acrylic acid gas and in condensing tower (also being referred to as to collect tower), contact, obtain acrylic acid aqueous solution with water.In this solution, add suitable extraction agent.In extraction tower, extract, and separating and extracting agent in the separated from solvent tower.Subsequently, separating acetic acid in the separated from acetic acid tower obtains crude acrylic acid.In rectifying tower, from this crude acrylic acid, isolate by product, obtain purified vinylformic acid by this.In addition,, pass through extraction tower and light component (light-matter) knockout tower then, obtain the crude propylene acid esters this vinylformic acid (purified vinylformic acid) esterification in esterification column.In rectifying tower, from this crude propylene acid esters, isolate by product (high boiling substance), obtain pure acrylate.

Incidentally, also there is the situation for preparing the acrylate of some kind by step shown in Figure 3.In this case, by product derives from vinylformic acid knockout tower or heavy constituent (heavy-matter) knockout tower as tower bottom distillate (bottoms).

In acrylate production technique shown in Figure 3, the vinylformic acid of vinylformic acid, alcohol, recovery and the alcohol of recovery charging are separately given esterifier.This esterifier is filled with catalyzer such as strong-acid ion exchange resin.The esterification mixture of extraction from this reactor, water that it comprises the ester that is generated, unreacted vinylformic acid, unreacted alcohol, generated etc. offers the vinylformic acid knockout tower.

At the bottom of the tower by this vinylformic acid knockout tower, discharge contains unreacted acrylic acid tower bottom distillate, and it is circulated to esterifier.The tower bottom distillate of part offers the heavy constituent knockout tower, and by separating heavy at the bottom of this Tata, heavy constituent is offered high boiling product decomposition reactor (not shown) decompose.The gained degradation production comprises valuable material, and is circulated in the technology.Degradation production circulation process portion extremely change according to processing condition.High-boiling-point impurity such as polymkeric substance remove to the outside from the high boiling point decomposition reactor.

Acrylate, the unreacted pure and mild water that generates is as overhead product, and the cat head by this vinylformic acid knockout tower obtains.The part overhead product is circulated to the vinylformic acid knockout tower as reflux, and the part with remainder offers extraction tower simultaneously.

The water that will be used for the alcohol extraction offers this extraction tower.To offer pure recovery tower by the effusive water that contains alcohol at the bottom of this Tata.Institute's distilled alcohol is circulated to esterifier.

To offer the low boilers knockout tower by the effusive crude propylene acid esters of extraction tower cat head.Low-boiling point material is discharged by cat head, and is circulated to certain part in the technology.Low-boiling point material circulation process portion extremely change according to processing condition.The crude propylene acid esters of therefrom removing low-boiling point material is offered acrylate product purification tower, and obtain highly purified acrylate by cat head.Tower bottom distillate is circulated to certain some of technology, because they comprise a large amount of vinylformic acid.Tower bottom distillate circulation process portion extremely change according to processing condition.

Replacement is with the solvent extration of extraction agent acrylic acid from acrylic acid aqueous solution, recently also adopt the azeotropic separation method, it comprises water and entrainment agent (entrainer) retort solution, obtaining comprising the azeotropic mixture cut of water and entrainment agent by the azeotropic separation column overhead, and by acrylic acid at the bottom of the tower of this tower.

In the occasion of synthesize methyl acrylic acid esters, replace propylene with the iso-butylene or the trimethyl carbinol.Oxidising process that this raw material experience is identical and esterification process subsequently obtain purified methacrylic ester.

For the situation of methacrylic acid and methacrylic ester, replace propylene with the iso-butylene or the trimethyl carbinol.Oxidising process that this raw material experience is identical and esterification process subsequently obtain purified methacrylic acid and purified methacrylic ester.

Incidentally, in order to generate (methyl) acrylate (acrylate or methacrylic ester), can also adopt such method, wherein utilize acid or other material as catalyzer, make (methyl) acrylate and the higher alcohols of lower alcohol carry out transesterify, obtain (methyl) acrylate of higher alcohols.Thick (methyl) acrylate that obtains by this transesterify through catalyst separating, concentrate and step such as purifying, obtain purified (methyl) acrylate.

By distillation/purifying crude acrylic acid, crude methacrylic acid, crude propylene acid esters and crude methacrylic acid ester are separated the cut that obtains and comprise useful byproducts, this by product contains Michael (Michael) adduct.Thereby, with these by-product destruction, to reclaim (methyl) vinylformic acid, its ester, raw alcohol etc.

Up to now, for decompose vinylformic acid or acrylic compound produce in as by product and the generation Michael addition adducts, make with the following method.The pyrolysis method (JP-A-11-012222) of catalyzer is not used in general employing in the vinylformic acid production technique, in the acrylate production technique, then adopt usually in the presence of Louis's (Lewis) acid or Lewis base, by heating the method (JP-A-49-055614 and JP-A-09-110791) of decomposing Michael addition adducts.In addition, as the technology of Michael addition adducts decomposition reaction, adopt reactive distillation technology usually, wherein the target cleavage reaction product is carried out decomposition reaction (JP-A-9-110791, JP-A-9-124551, and JP-A-8-225486) in by the distillation extraction.Also known method is that wherein the Michael addition adducts that generates as the by product in the vinylformic acid production stage carries out pyrolysis with the Michael addition adducts that generates as the by product in the acrylate production stage.The example comprise wherein Michael addition adducts under without the situation of catalyzer by reactive distillation technology and pyrolytic method (JP-A-8-225486), and wherein Michael addition adducts is to utilize the acid catalyst of high density and the method (JP-A-9-183752) of decomposing.

Adopting Lewis acid or Lewis base as catalyzer, to decompose the Michael addition adducts that generates as the by product in the acrylate production stage, and then reclaim in the method for (methyl) vinylformic acid, (methyl) acrylate and alcohol, there is such situation, wherein utilize the decomposition reaction condition of (methyl) vinylformic acid, (methyl) acrylate and the alcohol that are suitable for obtaining high-recovery, cause comprising the degradation production blocking pipe system of high density heavy constituent (thereby having high viscosity and low flow).

As mentioned above, the Michael addition adducts that generates as the by product in the acrylate production stage normally adopts such method to handle, wherein utilize Lewis acid or Lewis base as catalyzer, carry out decomposition reaction by reactive distillation technology, with acrylic acid, acrylate and alcohol.Yet, in the method, when the rate of recovery of effective constituents such as vinylformic acid, pure and mild acrylate improves, the compound of crossing heavy constituent accumulates at the bottom of the tower of decomposition reaction distillation tower with high density, this causes problems such as viscosity increase and flowability weaken, and under extreme case, cause terminal line clogging.In addition, the alcohol that also has decomposition reaction and generated is by quickening dehydration reaction with the effect of acid catalyst and then generating the problem of alkene or ether.This alkene and ether cause following detrimentally affect.This alkene or ether make and perhaps enter restive reactive system of under reduced pressure working or the pressure in the Distallation systm in the product acrylate, reduces its quality.

In addition, as for the Michael addition adducts that generates as the by product in the vinylformic acid production stage, by adopting the method acrylic acid of the pyrolytic reaction of wherein not using catalyzer.Yet this method also has problems, and for example improves the vinylformic acid rate of recovery and causes the resistates property reduction of flowing, and then cause the problem of terminal line clogging, as the situation of above-mentioned acrylate.

And disaggregating treatment is carried out in production technique separately usually in these two kinds of production technique, and each decomposition step all has problems, and for example needs high-temperature operation and quality matetrial, and because of decomposing resistates the blockage problem that the reduction of property takes place etc. that flows.

Therefore, with regard in vinylformic acid and the acrylate each, need a kind of method of decomposing Michael addition adducts, this method can stably obtain high-recovery, eliminates these problems simultaneously again.

On the other hand, be catalyzer with Lewis acid or Lewis base, make the Michael addition adducts that generates as the by product in (methyl) acrylate production stage stand decomposition reaction, to reclaim (methyl) vinylformic acid, also have problems in the method for (methyl) acrylate and alcohol, for example when adopting (methyl) vinylformic acid that is suitable for obtaining high-recovery, (methyl) acrylate and alcohol the decomposition reaction condition time, the amount of the ether that generates as by product significantly increases, and then pollution products, hinder vacuum system reactor or distillation tower normally to work, perhaps cause other problem.

In addition, the Michael addition adducts that wherein generates as the by product in (methyl) vinylformic acid production stage has following point in the method that does not have to stand the pyrolytic reaction acrylic acid under the situation of catalyzer: need high-temperature operation; The reactor that needs the use quality matetrial to make; It is poor to decompose the mobile property of resistates, causes blockage problem or decides problem with the operation fluctuation; Or the like.

Be example now, describe the problem that generates the ether by product in detail with method for preparing methyl acrylate and the method for preparing n-butyl acrylate.

In the step of the Michael addition adducts in decomposing methyl acrylate production, generate the dimethyl ether by product that comes from methyl alcohol.Because the extremely low normal boiling point that reaches 248.3K of this by product dimethyl ether, so it more is not easy at decomposition reactor self, reclaims condensation in the distillation tower that ether delivers to etc.Therefore, the generation of a large amount of by products causes it to hinder the problem of vacuum system control.

In the step of the Michael addition adducts in the classification n-butyl acrylate is produced, generate the di-n-butyl ether by product that comes from propyl carbinol.When reclaiming and send the cut to reactive system or purification system time that contains this di-n-butyl ether, can cause serious problem, because the normal boiling point of positive dibutyl ether is 413.4K, it is in close proximity to the normal boiling point 420K of n-butyl acrylate product, so can pollution products.

Therefore, the purpose separately of the present invention first and second aspects is to overcome existing the problems referred to above, and provide a kind of method, in the method, by product in (methyl) acrylic compound or (methyl) acrylate production stage, comprise the Michael reaction product, reclaiming (methyl) acrylate, and this method makes and can stably obtain the high rate of recovery by pyrolysis.

In addition, the purpose of third aspect present invention is to overcome existing the problems referred to above, and provide a kind of method, in the method, use acid as catalyzer, with the by product in (methyl) acrylate production stage, comprise that the Michael reaction product decomposes, reclaiming (methyl) vinylformic acid, (methyl) acrylate and alcohol, even and this method be suitable under the decomposition reaction condition of high-recovery the also inhibition meeting generation that brings the by product ether of problem to technology effectively.

And, the purpose of fourth aspect present invention provides the method for the by product of a kind of decomposition (methyl) acrylic compound production, this method is effectively and economic method, wherein the Michael addition adducts that generates as the by product in (methyl) vinylformic acid and (methyl) acrylate production stage lumps together and carries out disaggregating treatment simultaneously, and can reduce the generation of by product ether and alkene in the Michael addition adducts decomposition step significantly, stably keep the rate of recovery of high (methyl) vinylformic acid, (methyl) acrylate and alcohol simultaneously.

In addition, the purpose of fifth aspect present invention is to overcome existing the problems referred to above, and provide a kind of method, in the method, with acid as catalyzer, with the by product in (methyl) vinylformic acid and (methyl) acrylate production stage, comprise that the Michael reaction product decomposes, to reclaim (methyl) vinylformic acid, (methyl) acrylate and alcohol, even and this method is being suitable under the decomposition reaction condition of high-recovery, the also inhibition meeting generation that brings the by product ether of problem to technology effectively, and make the Michael addition adducts that is created in these two steps to handle simultaneously.

Summary of the invention

Method according to preparation (methyl) acrylic compound of first aspect present invention is the method with (methyl) vinylformic acid production unit and (methyl) acrylate production unit, by product pyrolysis that wherein will extraction from the purification step of purifying (methyl) acrylate reactions mixture, therefrom to reclaim (methyl) acrylate, the pyrolytic reaction that it is characterized in that by product is carried out in liquid phase in fact, and the partial thermal decomposition reaction product is returned (methyl) acrylate purification step at least.

In addition, the reactions steps that comprises generation (methyl) acrylate according to the method for preparation (methyl) acrylate of second aspect present invention, and the by product that pyrolysis is separated from generate step is therefrom to reclaim the step of (methyl) vinylformic acid, (methyl) acrylate and alcohol, it is characterized in that what described pyrolytic reaction came down to carry out in liquid phase, and at least 50% pyrolytic reaction product returns step upstream.

When pyrolysis in liquid phase comprises the by product of Michael addition adducts, and pyrolytic reaction product circulation time as second aspect present invention of at least 50%, can reclaim (methyl) acrylate by high-recovery, and can prevent technology obstruction etc.

And, be included in acid catalyst according to the method for the by product of decomposition (methyl) the acrylate production of third aspect present invention and exist and decompose the by product that (methyl) acrylate is produced down, it is characterized in that the add-on of described acid catalyst is counted 0.1～1.0% weight by by product.

In the step of decomposing the Michael addition adducts that generates as the by product in the acrylate production stage, use a large amount of acid catalysts up to now so that improve the rate of recovery.Yet, use the shortcoming of a large amount of catalyzer to be, the dehydration dimerization reaction of alcohol causes the generation of ether by product, and the ether that is generated can be as described above such, hinders the control or the pollution products of vacuum system.

As result of study, the inventor finds, reduces rather than the amount that increases catalyst system therefor can reduce the ether generation effectively and boosts productivity.

And according to a third aspect of the present invention based on this discovery, Michael addition adducts can be decomposed effectively.

In addition, be included in the mixture of the by product that by product that pyrolysis in the liquid phase (methyl) vinylformic acid produces and (methyl) acrylate produce according to the method for the by product of decomposition (methyl) the acrylic compound production of fourth aspect present invention, it is characterized in that at least 50% pyrolytic reaction product returns (methyl) acrylate production stage.

According to a forth aspect of the invention, the by product that (methyl) acrylate is produced (promptly derives from the tower bottom distillate of rectifying tower, comprise the by product of conduct (methyl) acrylate production of high density and the Michael addition adducts that generates), the by product of producing with (methyl) vinylformic acid (promptly derives from the tower bottom distillate of rectifying tower, comprise the by product of conduct (methyl) vinylformic acid production of high density and the Michael addition adducts that generates) decompose by pyrolytic reaction rather than by reactive distillation technology together, keep liquid phase simultaneously.In addition, the pyrolytic reaction product with vast scale is circulated to (methyl) acrylate production stage.Because this structure, when particularly carrying out pyrolytic reaction without catalyzer, the rate of recovery of (methyl) vinylformic acid, (methyl) acrylate and alcohol can be improved, and can stablize operation constantly for a long time, suppresses the generation of by product ether or alkene simultaneously.

One of advantage of fourth aspect present invention is, that need make with quality matetrial and in correlation technique, have problem such as obstructions and need be installed on decomposition reactor in (methyl) vinylformic acid production stage and (methyl) acrylate production stage respectively, can two combine into one, it can only be installed in (methyl) acrylate production stage, and can reclaim the valuable material that obtains by decomposition with high-recovery in (methyl) acrylate production stage.Thereby engineering cost, labor cost and general facilities expense all can reduce significantly, and can reduce material cost.

Another major advantage of fourth aspect present invention is, though the by product of (methyl) acrylate production up to now adopts acid catalyst to decompose, but the method for high moment of torsion fourth aspect present invention can prevent to come from the by product-ether of alcohol or the generation of alkene effectively, and this is to adopt the problem that exists in the decomposition reaction of acid catalyst.Its reason is as follows.

(1) since decomposition reaction can under the situation of not using catalyzer, carry out effectively, the catalytic dehydration reaction process of acid catalyst is restricted, and come from alcohol by product-ether or the generation of alkene be inhibited.

(2) by product of (methyl) vinylformic acid production does not comprise the compound that comes from alcohol.Therefore, the by product of handling the production of (methyl) vinylformic acid simultaneously can produce diluting effect, and this has reduced determining alcohol, and then has suppressed dehydration reaction.

(3) handle the by product that (methyl) vinylformic acid is produced simultaneously, obtain the degradation production that (methyl) acrylic acid concentration has increased.Therefore, the alcohol that decomposition reaction generated is stablized by carrying out esterification with (methyl) vinylformic acid, no longer carries out dehydration reaction.By product-the ether of alcohol or the generation of alkene have so just been suppressed to come from.

Although (methyl) vinylformic acid not only experiences Michael reaction, and be easy to carry out Raolical polymerizable, but according to fourth aspect present invention, (methyl) acrylic acid concentration reduces by the by product of together processing (methyl) vinylformic acid production and the by product of (methyl) acrylate production.Thereby this method has also produced the effect of undesirable polyreaction during the pyrolytic reaction that suppresses to carry out under the high temperature extraly.

Being also advantageous in that of a fourth aspect of the present invention, because the by product that (methyl) vinylformic acid is produced and the by product of (methyl) acrylate production are together handled, so decomposing the flow of resistates, increases the unit time, and in the resistates discharge tube, resistates can have the flowability that has improved.

Particularly, preferred a fourth aspect of the present invention is carried out in the following manner.Utilize thin-film evaporator to concentrate the tower bottom distillate of rectifying tower, it comprises the Michael reaction product that generates as the by product in (methyl) acrylate production stage.The Michael reaction product that will generate as the by product in (methyl) vinylformic acid production stage is added in the gained enriched material, makes feed material.Pyrolytic reaction was preferably carried out under 120～280 ℃ 0.5～50 hour, was keeping liquid phase basically under the condition like this.Preferred at least 80% gained pyrolytic reaction product is circulated to (methyl) acrylate production stage, and preferred cycle is to the thin-film evaporator as the reboiler of rectifying tower.

In addition, be included in acid catalyst according to the method for the by product of decomposition (methyl) the acrylic compound production of fifth aspect present invention and have the mixture that decomposes the by product that by product that (methyl) vinylformic acid produces and (methyl) acrylate produce down, it is characterized in that the add-on of described acid catalyst is counted 0.1～1.0% weight by by product.

In the step of decomposing the Michael addition adducts that generates as the by product in the acrylate production stage, use a large amount of acid catalysts up to now so that improve the rate of recovery.Yet, use the shortcoming of a large amount of catalyzer to be, the dehydration dimerization reaction of alcohol causes the generation of ether by product, and the ether that is generated can be as described above such, hinders the control or the pollution products of vacuum system.

As result of study, the inventor finds, reduces rather than the amount that increases catalyst system therefor can reduce the ether generation effectively and boosts productivity.

In a fifth aspect of the present invention, owing to the Michael reaction product that generates as the by product in (methyl) vinylformic acid production stage and the Michael addition adducts that generates as the by product in the acrylate production stage together decompose, therefore can carry out the decomposition of Michael addition adducts effectively.

More particularly, the present invention relates to

(1). the method for a kind of preparation (methyl) acrylic compound, this method has (methyl) vinylformic acid production unit and (methyl) acrylate production unit, and the by product that wherein will derive from the purification step of purifying (methyl) acrylate reactions mixture carries out pyrolysis, therefrom to reclaim (methyl) acrylate, it is characterized in that what the pyrolytic reaction of described by product came down to carry out in liquid phase, and the partial thermal decomposition reaction product is returned (methyl) acrylate purification step at least.

(2). the method according to above-mentioned (1) is characterized in that at least 50% pyrolytic reaction product returns purification step.

(3). the method according to above-mentioned (1) or (2) is characterized in that described by product is from the tower bottom distillate that is used for the distillation tower of separating heavy (heavy matter) in (methyl) acrylate purification step.

(4). according to each method in above-mentioned (1)～(3), it is characterized in that the pyrolytic reaction of described by product is carried out in the presence of acid catalyst, and the add-on of described acid catalyst is counted 0.1～1.0% weight by by product.

(5). according to each method in above-mentioned (1)～(3), it is characterized in that the mixture of the by product that will the stand pyrolytic reaction by product that to be the by product produced of (methyl) vinylformic acid produce with (methyl) acrylate.

(6). according to the method for above-mentioned (5), the by product that it is characterized in that the production of described (methyl) vinylformic acid is from the tower bottom distillate that is used for the rectifying tower of separating heavy in (methyl) purifying acrylic acid step, and the by product of described (methyl) acrylate production is the tower bottom distillate from the rectifying tower of separating heavy in (methyl) acrylate purification step.

(7). according to the method for above-mentioned (5) or (6), it is characterized in that the by product that (methyl) vinylformic acid produces and the mixture of the by product of (methyl) acrylate production are to carry out pyrolytic in the presence of acid catalyst, and the add-on of described acid catalyst is counted 0.1～1.0% weight by by product.

(8). according to each method in above-mentioned (1)～(7), it is characterized in that the rectifying tower that is used for separating heavy in described (methyl) acrylate purification step is equipped with thin-film evaporator as reboiler.

(9). according to each method in above-mentioned (1)～(8), it is characterized in that at least 80% pyrolytic reaction product returns (methyl) acrylate purification step.

(10). according to each method in above-mentioned (1)～(9), the temperature that it is characterized in that described pyrolytic reaction is 120～280 ℃, and the cycle of pyrolytic reaction is 0.5～50 hour.

(11). the method for a kind of preparation (methyl) acrylate, it comprises the reactions steps of generation (methyl) acrylate, and the by product of separating from generate step carries out pyrolysis therefrom to reclaim the step of (methyl) acrylate, it is characterized in that what described pyrolytic reaction came down to carry out in liquid phase, and at least 50% pyrolytic reaction product returns step upstream.

(12). according to method according to preparation (methyl) acrylate of above-mentioned (11), the by product that it is characterized in that the formation reaction of (methyl) acrylate is the tower bottom distillate that is used for the distillation tower of separating heavy in the purification step of (methyl) acrylate of generating of purifying.

(13). the method according to according to preparation (methyl) acrylate of above-mentioned (12) is characterized in that described distillation tower is equipped with thin-film evaporator as reboiler.

(14). according to the method for each preparation (methyl) acrylate in above-mentioned (11)～(13); the by product that it is characterized in that the formation reaction of described (methyl) acrylate comprises Michael addition adducts, and this adduct is to form by alpha-position or β-position that water, methyl alcohol, ethanol, butanols or (methyl) vinylformic acid add to (methyl) acryl.

(15). according to the method for each preparation (methyl) acrylate in above-mentioned (11)～(14), the temperature that it is characterized in that pyrolytic reaction is 120～280 ℃, and the cycle of pyrolytic reaction is 0.5～50 hour.

(16). the method according to each preparation (methyl) acrylate in above-mentioned (11)～(15) is characterized in that at least 80% pyrolytic reaction product returns step upstream.

(17). the method for the by product that a kind of decomposition (methyl) acrylate is produced, this method is included in acid catalyst and has the by product that decomposes the production of (methyl) acrylate down, it is characterized in that the add-on of described acid catalyst is counted 0.1～1.0% weight by by product.

(18). the method for the by product of producing according to decomposition (methyl) acrylate of above-mentioned (17), the by product that it is characterized in that the production of described (methyl) acrylate is from the tower bottom distillate that is used for the rectifying tower of separating heavy in (methyl) acrylate purification step.

(19). the method for the by product of producing according to decomposition (methyl) acrylate of above-mentioned (17) or (18); the by product that it is characterized in that the production of described (methyl) acrylate comprises Michael addition adducts, and this adduct is to form by alpha-position or β-position that water, methyl alcohol, ethanol, propyl carbinol or (methyl) vinylformic acid add to (methyl) acryl.

(20). according to the method for the by product of each decomposition (methyl) acrylate production in above-mentioned (17)～(19), the temperature that it is characterized in that described disaggregating treatment is 120～200 ℃, and the cycle of described disaggregating treatment is 0.5～20 hour.

(21). the method for the by product that a kind of decomposition (methyl) acrylic compound is produced, this method comprises that the mixture with the by product of the by product of (methyl) vinylformic acid production and the production of (methyl) acrylate carries out pyrolysis in liquid phase, is characterized in that at least 50% pyrolytic reaction product returns (methyl) acrylate production stage.

(22). the method for the by product of producing according to decomposition (methyl) acrylic compound of above-mentioned (21), the by product that it is characterized in that the production of described (methyl) vinylformic acid is from the tower bottom distillate that is used for the rectifying tower of separating heavy in (methyl) purifying acrylic acid step, and the by product of described (methyl) acrylate production is from the tower bottom distillate that is used for the rectifying tower of separating heavy in (methyl) acrylate purification step.

(23). the method for the by product of producing according to decomposition (methyl) acrylic compound of above-mentioned (22) is characterized in that the rectifying tower that is used for separating heavy in described (methyl) acrylate purification step is equipped with thin-film evaporator as reboiler.

(24). according to the method for the by product of each decomposition (methyl) acrylic compound production in above-mentioned (21)～(23); it is characterized in that the by product that (methyl) vinylformic acid produces and the mixture of the by product of (methyl) acrylate production comprise Michael addition adducts, described adduct is to form by alpha-position or β-position that water, alcohol or (methyl) vinylformic acid add to (methyl) acryl.

(25). according to the method for the by product of each decomposition (methyl) acrylic compound production in above-mentioned (21)～(24), the temperature that it is characterized in that pyrolytic reaction is 120～280 ℃, and the cycle of pyrolytic reaction is 0.5～50 hour.

(26). the method according to the by product of each decomposition (methyl) acrylic compound production in above-mentioned (21)～(25) is characterized in that at least 80% pyrolytic reaction product returns (methyl) acrylate production stage.

(27). the method for the by product that a kind of decomposition (methyl) acrylic compound is produced, under the existence that this method is included in, decompose the by product of (methyl) vinylformic acid production and the mixture of the by product of (methyl) acrylate production, it is characterized in that the add-on of described acid catalyst is counted 0.1～1.0% weight by by product.

(28). the method for the by product of producing according to decomposition (methyl) acrylic compound of above-mentioned (27), the by product that it is characterized in that the production of described (methyl) vinylformic acid is from the tower bottom distillate that is used for the rectifying tower of separating heavy in (methyl) purifying acrylic acid step, and the by product of described (methyl) acrylate production is from the tower bottom distillate that is used for the rectifying tower of separating heavy in (methyl) acrylate purification step.

(29). the method for the by product of producing according to decomposition (methyl) acrylic compound of above-mentioned (27) or (28); it is characterized in that the by product that described (methyl) vinylformic acid produces and the mixture of the by product of (methyl) acrylate production comprise Michael addition adducts, this adduct is to form by alpha-position or β-position that water, alcohol or (methyl) vinylformic acid add to (methyl) acryl.

(30). according to the method for the by product of each decomposition (methyl) acrylic compound production in above-mentioned (27)～(29), the temperature that it is characterized in that described disaggregating treatment is 120～200 ℃, and the cycle of described disaggregating treatment is 0.5～20 hour.

Description of drawings

Fig. 1 is the schema according to the preparation acrylate of second aspect present invention.

Fig. 2 is one of example of preparation vinylformic acid and acrylate schema.

Fig. 3 prepares another example of acrylate schema.

Embodiment

First and second aspects of the present invention will be described in detail in detail below.

Method according to preparation (methyl) acrylic compound of first aspect present invention is characterised in that at least 50% pyrolytic reaction product returns purification step.

Method according to preparation (methyl) acrylic compound of first aspect present invention is characterised in that by product is the tower bottom distillate of the distillation tower of separating heavy in (methyl) acrylate purification step.

Method according to preparation (methyl) acrylic compound of first aspect present invention is characterised in that the pyrolytic reaction of by product is carried out in the presence of acid catalyst, and the add-on of acid catalyst is counted 0.1～1.0% weight by by product.

Method according to preparation (methyl) acrylic compound of first aspect present invention is characterised in that, the mixture of the by product that the stand pyrolytic reaction by product that to be the by product produced of (methyl) vinylformic acid produce with (methyl) acrylate.

Method according to preparation (methyl) acrylic compound of first aspect present invention is characterised in that, the by product of (methyl) vinylformic acid production is from the tower bottom distillate that is used for the rectifying tower of separating heavy in (methyl) purifying acrylic acid step, and the by product of (methyl) acrylate production is from the tower bottom distillate that is used for the rectifying tower of separating heavy in (methyl) acrylate purification step.

Method according to preparation (methyl) acrylic compound of first aspect present invention is characterised in that, the by product that (methyl) vinylformic acid is produced is to carry out pyrolytic in the presence of acid catalyst with the mixture of the by product of (methyl) acrylate production, and the add-on of acid catalyst is counted 0.1～1.0% weight by by product.

Method according to preparation (methyl) acrylic compound of first aspect present invention is characterised in that the rectifying tower that is used for separating heavy in (methyl) acrylate purification step is equipped with thin-film evaporator as reboiler.

Method according to preparation (methyl) acrylic compound of first aspect present invention is characterised in that at least 80% pyrolytic reaction product is back to (methyl) acrylate purification step.

Method according to preparation (methyl) acrylic compound of first aspect present invention is characterised in that the temperature of pyrolytic reaction is 120～280 ℃, and the cycle of pyrolytic reaction is 0.5～50 hour.

(methyl) acrylate in the second aspect present invention there is not concrete restriction.Yet the example comprises (methyl) methyl acrylate, (methyl) ethyl propenoate, (methyl) n-butyl acrylate, (methyl) isobutyl acrylate, (methyl) 2-EHA, (methyl) vinylformic acid ester in the different ninth of the ten Heavenly Stems, (methyl) isodecyl acrylate etc.

The Michael addition adducts of second aspect present invention is to result from the reactions steps of preparation (methyl) acrylate or the by product in the purification step; and be by (methyl) vinylformic acid, alcohol or water, the compound that forms with the Michael addition of the compound that has (methyl) acryl in the preparation that is present in these esters.The examples for compounds with (methyl) acryl that exists in this preparation comprises (methyl) vinylformic acid as raw material; (methyl) acrylate; carboxylic acid with acryl; β-the acryloxy propionic or the Beta-methyl acryloxy isopropylformic acid (dimer hereinafter) that form of the Michael addition by (methyl) vinylformic acid self for example; (methyl) vinylformic acid tripolymer (tripolymer hereinafter) that forms by (methyl) vinylformic acid and dimeric Michael addition; (methyl) vinylformic acid tetramer (tetramer hereinafter) that forms by (methyl) vinylformic acid and trimerical Michael addition, and corresponding (methyl) acrylate of forming of the esterification by these carboxylic acids with (methyl) acryl and alcohol.The specific examples of the Michael addition adducts among the present invention comprises β-acryloxy propionic, Beta-methyl acryloxy isopropylformic acid, and ester; β-alkoxyl group propionic acid or β-alkoxyl group isopropylformic acid and ester thereof; Ethylene lactic acid or isopropylformic acid and ester thereof; The dimer that these are sour, tripolymer, the tetramer etc.; The ester that these are sour; Their β-acryloxy replaces form and beta-hydroxy replacement form etc.

In a second aspect of the present invention, the by product of preferred (methyl) acrylate formation reaction comprises by water, methyl alcohol, ethanol, butanols or (methyl) vinylformic acid and adds to alpha-position of (methyl) acryl or the Michael addition adducts that β-position forms.

In a second aspect of the present invention, (methyl) vinylformic acid that is preferred for preparation (methyl) acrylate is that the catalytic vapor phase oxidation by propane, propylene, propenal, iso-butylene, the trimethyl carbinol etc. obtains.Water cools off the gasiform oxidation reaction product rapidly.By the azeotropic distn of employing entrainment agent or by the extraction process that adopt solvent carry out water/vinylformic acid separation thereafter.In addition, separate the low-boiling compound that comprises acetate, separate then and comprise the heavy constituent of Michael addition adducts, and then obtain highly purified (methyl) vinylformic acid.Incidentally, water can utilize entrainment agent to separate simultaneously with acetate.

In order to prepare (methyl) acrylate of second aspect present invention, can use (methyl) vinylformic acid and pure esterification method, also can use the acrylate of lower alcohol and higher alcohols to carry out the method for transesterify with the acrylate of preparation higher alcohols.The preparation method can be interrupter method or continuous processing.The common acid catalyzer is as the catalyzer of esterification or transesterify.

Preferably the method according to preparation (methyl) acrylate of second aspect present invention comprises reactions steps and purification step, wherein must pass through cleaning, extracting, evaporating, distillation etc., to carry out catalyst separating, concentrated/purifying etc. in the crude acrylic acid ester solution of reactions steps.The condition of reactions steps is the mol ratio between (methyl) vinylformic acid or (methyl) acrylate and the alcohol, kind and quantity, reactive mode and the reaction conditions etc. of reaction catalyst system therefor as raw material, can suitably choose according to the kind of raw alcohol.

In a second aspect of the present invention, the Michael addition adducts that generates as the main by product in the esterif iotacation step, accumulate on the tower of the distillation tower (the acrylate rectifying tower among Fig. 1) that reclaims effective constituent with high density as heavy constituent at the bottom of.Although tower bottom distillate comprises the above-mentioned Michael addition adducts of high density, they also comprise the vinylformic acid and/or the acrylate of a great deal of.In addition, tower bottom distillate comprises polymerization retarder used in heavy constituent such as the technology, oligopolymer that is generated in the technology and polymkeric substance, and be included in the raw material or the high-boiling-point impurity in the resultant reaction product.Also exist tower bottom distillate to comprise the situation of catalyst system therefor in esterification or the step of transesterification.

In the presence of Lewis acid or Lewis base, by the thermal degradation tower bottom distillate, and the effective constituent of recovery gained, it sends it to reactions steps or purification step.The distillation tower of separating heavy can be any acrylic acid distillation tower of isolating from heavy constituent, isolates the distillation tower of acrylate from heavy constituent, isolates the distillation tower of vinylformic acid, pure and mild acrylate etc. from heavy constituent.

Preferred distillation tower is equipped with reboiler.Preferred this reboiler is a thin-film evaporator, because tower bottom distillate has high viscosity and polymerizability.Type to thin-film evaporator does not have concrete restriction.Incidentally, distillation tower can be equipped with thermal siphon type reboiler, pump circulation reboiler etc., and thin-film evaporator can be as the utility appliance of these reboilers.

In a second aspect of the present invention, the decomposition reaction of Michael addition adducts can be undertaken by any methods such as continuous processing, interrupter method, Semi-batch Process, intermittent take-off methods.Yet, preferred continuous processing.Type to reactor does not have concrete restriction yet, can use the reactor of any kind, as the type tubular reactor of flowing through, fully mixed type stirred reactor, round-robin complete, has the reactor in pure hole etc.

The pyrolytic reaction of Michael addition adducts is not by reactive distillation technology but carries out under the condition that keeps liquid phase basically.Although pyrolysis does not always need catalyzer, can use Lewis acid or lewis-base catalyst.

The temperature of preferred decomposition reaction is 120～280 ℃, particularly 140～240 ℃.The fluid retention time of calculating from the liquid discharge amount is preferably 0.5～50 hour, particularly 1～10 hour.Under the situation that decomposition reaction is carried out continuously, the fluid retention time of calculating from the liquid discharge amount can be considered as the reaction times.For example, when the liquid capacity of reactor is 500L, and the liquid discharge amount is when being 100L/H, and then the time of storing is 5 hours.

In a second aspect of the present invention, most pyrolytic reaction product circulates.The part residuum obtains waste or fuel as decomposing the resistates discharging.Although pyrolytic reaction product circulation institute position is not extremely had concrete restriction, preferably with this ship affair feed at the bottom of the tower of heavy constituent knockout tower, perhaps feed is in the thin-film evaporator of the reboiler that is used as the heavy constituent knockout tower.Preferred higher circulation ratio can reduce the amount of the resistates that will discharge like this.Particularly, the pyrolytic reaction product of preferred cycle at least 80%.Along with the increase of circulation ratio, the rate of recovery uprises, and resistates becomes and has higher viscosity and worse flowability.Therefore, its upper limit can be chosen to be the OK range that can move continuously.

To explain a third aspect of the present invention in more detail below.

(methyl) acrylate to third aspect present invention does not have concrete restriction.Yet, preferred (methyl) acrylate of being made by the raw polyol that does not have side chain is as (methyl) methyl acrylate, (methyl) ethyl propenoate, (methyl) n-butyl acrylate, the just own ester of (methyl) vinylformic acid, (methyl) vinylformic acid n-octyl and (methyl) vinylformic acid methoxyl group ethyl ester.(methyl) n-butyl acrylate wherein most preferably.

Michael addition adducts is the by product that generates in reactions steps of preparation (methyl) acrylate or purification step; and be by (methyl) vinylformic acid, alcohol or water and have the compound that the Michael addition two of the compound of (methyl) acryl forms that described compound with (methyl) acryl is present in the preparation process of these esters.The examples for compounds that has (methyl) acryl and be present in the preparation process comprises (methyl) vinylformic acid; β-acryloxy propionic or the Beta-methyl acryloxy isopropylformic acid (hereinafter dimer) of carboxylic acid as forming by (methyl) vinylformic acid self Michael addition; (methyl) vinylformic acid tripolymer (tripolymer hereinafter) that forms by (methyl) vinylformic acid and dimeric Michael addition; and (methyl) vinylformic acid tetramer (tetramer hereinafter), and corresponding (methyl) acrylate that forms by these carboxylic acids with (methyl) acryl with pure esterification.The specific examples of the Michael addition adducts of third aspect present invention comprises β-acryloxy propionic, Beta-methyl acryloxy isopropylformic acid, and ester; β-alkoxyl group propionic acid or β-alkoxyl group isopropylformic acid and ester thereof; Ethylene lactic acid or isopropylformic acid and ester thereof or aldehyde; The dimer that these are sour, tripolymer, the tetramer etc.; Their ester; Its β-acryloxy replaces form, and β-alkoxyl group replaces form, and beta-hydroxy replaces form; Or the like.

In a third aspect of the present invention; preferably the by product of (methyl) acrylate production comprises Michael addition adducts, and this Michael addition adducts is to form by alpha-position or β-position that water, methyl alcohol, ethanol, propyl carbinol or (methyl) vinylformic acid add to (methyl) acryl.

In a third aspect of the present invention, (methyl) vinylformic acid that is used for preparing (methyl) acrylate can be by the method preparation identical with second aspect present invention.

The method of preparation (methyl) acrylate that can be used for third aspect present invention is identical with the method for second aspect present invention.

Method according to preparation (methyl) acrylate of third aspect present invention can be identical with the method for second aspect present invention.

The Michael addition adducts that generates as the main by product of esterif iotacation step accumulates on heavy constituent and high density at the bottom of the tower of the distillation tower that reclaims effective constituent.

In a third aspect of the present invention, the decomposition reaction of Michael addition adducts can be undertaken by any methods such as continuous processing, interrupter method, Semi-batch Process, intermittent take-off methods.Yet, preferred continuous processing.Type to reactor does not have concrete restriction yet, can use the reactor of any kind, as flow pattern reactor under flow through type tubular reactor, the film, mixed type stirred reactor, round-robin complete etc. fully.The useful component that comprises in order to reclaim in the cleavage reaction product can use the method that during reaction obtains useful component by evaporation or distillation, also can use the method that obtains useful component after decomposition reaction by evaporation or distillation.Yet, in order to obtain high-recovery, preferred preceding a kind of method, i.e. reactive distillation technology.

Under the situation of using reactive distillation technology, reaction pressure greatly depends on temperature of reaction, and this will be described hereinafter.Under the pressure that is adopted, most useful component and most useful component such as vinylformic acid, acrylate and alcohol that is contained in the decomposition reaction feed, all gasifications that generate by decomposition reaction.

Catalyzer is selected from mineral acid such as sulfuric acid and phosphoric acid, organic acid such as methylsulfonic acid and tosic acid etc.Yet, preferred organic acid.

In a third aspect of the present invention, the concentration of acid catalyst is 0.1～1.0% weight, is preferably 0.2～0.8% weight, based on feed liquid.

The temperature of decomposition reaction is preferably 120～200 ℃.The fluid retention time of calculating from the liquid discharge amount is preferably 0.5～50 hour, particularly 2～20 hours.Under the situation that decomposition reaction is carried out continuously, the fluid retention time of calculating from the liquid discharge amount can be considered as the reaction times.For example, when the liquid capacity of reactor is 500L, and the liquid discharge amount is when being 100L/H, and then the time of storing is 5 hours.

Incidentally, the common decomposition reaction condition that is adopted up to now comprises counts 5～15% tosic acid concentration, 180～230 ℃ decomposition reaction temperature, and 0.1～4.0 hour reaction times by the feed liquid weight.The inventor generates the reaction of ether by product and the decomposition reaction of Michael addition adducts from a plurality of angle analysis, and finds to be catalyzer and to adopt lower decomposition temperature to help suppressing the generation of ether by product with the acid of lower concentration.

When the decomposition reaction condition that adopts according to third aspect present invention, it is slow a little that the process of the decomposition reaction of Michael addition adducts becomes.Yet, when the reaction times extends to a certain degree, can obtain the sufficiently high rate of recovery.

Incidentally, various result of experiment show, the decomposition resistates that under decomposition reaction condition, obtains according to third aspect present invention, and the decomposition resistates that obtains under common decomposition reaction condition has more low viscosity and better mobile.

The embodiment of the method for the by product that decomposition (methyl) acrylic compound according to fourth aspect present invention produces will be described in detail in detail below.Hereinafter, term (methyl) propenal is represented any one or two kinds in propenal and the Methylacrylaldehyde.

(methyl) vinylformic acid of preferred fourth aspect present invention is that the catalytic vapor phase oxidation by propane, propylene, propenal, iso-butylene, the trimethyl carbinol etc. obtains.Water cools off the gasiform oxidation reaction product rapidly.By adopt the azeotropic distn of entrainment agent, perhaps by the extraction process that adopt solvent carry out water/(methyl) vinylformic acid separate thereafter.In addition, separate the low-boiling compound that comprises acetate, thereafter, separate and comprise the heavy constituent of Michael addition adducts, thereby obtain highly purified (methyl) vinylformic acid.Incidentally, water can separate with entrainment agent simultaneously with acetate.Because Michael addition adducts is with the accumulation of heavy constituent and high density, so preferred this cut is generally the tower bottom distillate of rectifying tower, the by product of producing with (methyl) acrylate mixes, and handles the mixture of gained generally.

(methyl) acrylate to fourth aspect present invention does not have concrete restriction, the example comprises (methyl) methyl acrylate, (methyl) ethyl propenoate, (methyl) n-butyl acrylate, (methyl) isobutyl acrylate, the just own ester of (methyl) vinylformic acid, (methyl) 2-EHA, (methyl) vinylformic acid n-octyl, (methyl) vinylformic acid methoxyl group ethyl ester, (methyl) vinylformic acid ester in the different ninth of the ten Heavenly Stems, (methyl) isodecyl acrylate etc.Yet, preferred especially (methyl) acrylate that makes by the raw alcohol that does not have side chain.Particularly, preferred (methyl) methyl acrylate, (methyl) ethyl propenoate and (methyl) n-butyl acrylate.

Michael addition adducts is the by product that generates in reactions steps of preparation (methyl) vinylformic acid and (methyl) acrylate or purification step; and be by (methyl) vinylformic acid, acetate, alcohol or water and have the compound that the Michael reaction of the compound of (methyl) acryl forms that described compound with (methyl) acryl is present in the preparation process of acid or ester.The examples for compounds that has (methyl) acryl and be present among the preparation technology comprises (methyl) propenal; (methyl) vinylformic acid; carboxylic acid with (methyl) acryl; as β-acryloxy propionic or the Beta-methyl acryloxy isopropylformic acid (hereinafter being collectively referred to as dimer) that forms by (methyl) vinylformic acid self Michael addition; (methyl) vinylformic acid tripolymer (tripolymer hereinafter) that forms by (methyl) vinylformic acid and dimeric Michael addition; and (methyl) vinylformic acid tetramer (tetramer hereinafter) that forms by (methyl) vinylformic acid and trimerical Michael addition, and corresponding (methyl) acrylate that forms by these carboxylic acids with (methyl) acryl with pure esterification.The example also comprises the compound that is formed with the Michael addition of (methyl) propenal by (methyl) vinylformic acid equally.The specific examples of the Michael addition adducts of fourth aspect present invention comprises β-acryloxy propionic or Beta-methyl acryloxy isopropylformic acid and their ester and aldehyde (β-acryloxy propionic aldehyde or Beta-methyl acryloxy isobutyric aldehyde); β-alkoxyl group propionic acid and ester thereof; Ethylene lactic acid or beta-hydroxy isopropylformic acid and ester and aldehyde; The dimer that these are sour, tripolymer, the tetramer etc.; Their ester; The form that β-acryloxy replaces, the form that β-acetoxyl group replaces, the form that β-alkoxyl group replaces, and the form of beta-hydroxy replacement; Or the like.Incidentally, the compound that also exists the Michael addition by acetate and (methyl) acryl to form is although it is micro-.

In a fourth aspect of the present invention; preferably the by product produced of (methyl) vinylformic acid comprises Michael addition adducts with the mixture of the by product of (methyl) acrylate production, and this Michael addition adducts is to form by alpha-position or β-position that water, alcohol or (methyl) vinylformic acid add to (methyl) acryl.

The method of preparation (methyl) acrylate that can be used for fourth aspect present invention is identical with method in the second aspect present invention.

The method of preferred preparation (methyl) acrylate comprises reactions steps and purification step, in purification step, thick (methyl) acrylate solution that derives from reactions steps is through unit operations such as purification, extraction, evaporation, distillations, to carry out catalyst separating, concentrated/purifying etc.The condition of reactions steps is (methyl) vinylformic acid or (methyl) acrylate and the mol ratio of alcohol as raw material, is used for the kind and the quantity of catalyst for reaction, and reactive mode, and reaction conditions can suitably be chosen according to the kind of raw alcohol.

As the main by product in the reaction and the Michael addition adducts that generates accumulates on high density at the bottom of the tower of distillation tower (rectifying tower) of separating heavy.Therefore, in a fourth aspect of the present invention, tower bottom distillate be by with them with handling from the by product pyrolysis that preceding step, sends over of (methyl) vinylformic acid production.Reclaim the effective constituent of gained, and send it to the reactions steps or the purification step of (methyl) acrylate.

Incidentally, the distillation tower of separating heavy can change according to the kind of the technology that is adopted and prepared (methyl) acrylate.Usually, this distillation tower comprises separation (methyl) acrylic acid distillation tower from heavy constituent, separates the distillation tower of (methyl) acrylate from heavy constituent, and separates the distillation tower of (methyl) vinylformic acid, pure and mild (methyl) acrylate from heavy constituent.Yet a fourth aspect of the present invention can be applied to all these situations.

Distillation tower (rectifying tower according to the separating heavy in the step of preparation (methyl) acrylate of fourth aspect present invention; Hereinafter be referred to as " heavy constituent knockout tower " sometimes), reboilers such as thermal siphon type, forced circulation type can be housed.Yet, also can use the utility appliance of thin-film evaporator as these reboilers.More preferably adopt the rectifying tower of thin-film evaporator as unique reboiler.Type to thin-film evaporator does not have concrete restriction.The preferred film vaporizer is that as the reason of the reboiler of rectifying tower the tower bottom distillate of heavy constituent knockout tower has high viscosity and polymerizability.

Although the tower bottom distillate of heavy constituent knockout tower comprises the Michael addition adducts of above-mentioned high density, they also comprise (methyl) vinylformic acid and/or (methyl) acrylate of a great deal of.In addition, tower bottom distillate also comprises employed polymerization retarder in heavy constituent such as the technology, oligopolymer that generates in the technology and polymkeric substance, and high-boiling-point impurity that is comprised in the raw material and the reaction product that comes from them.Also exist tower bottom distillate to comprise the situation of catalyst system therefor in esterification or the step of transesterification.Yet from suppressing the viewpoint that alkene during the decomposition reaction or ether by product generate, preferred tower bottom distillate does not contain acid catalyst.

As mentioned above, at the bottom of the Michael addition adducts that is created on (methyl) vinylformic acid production stage accumulates on the tower of the distillation tower (rectifying tower) that separates (methyl) acrylic acid product in the component therefrom with high density usually.Tower bottom distillate also comprises a great deal of (methyl) vinylformic acid, and further comprises oligopolymer and the heavy metal that is generated in polymerization retarder used in the technology and the technology.

In a fourth aspect of the present invention, comprise the pyrolytic reaction of the mixture of the by product that by product that (methyl) vinylformic acid of Michael addition adducts produces and (methyl) acrylate produce, can be undertaken by any technologies such as continuous processing, interrupter method, Semi-batch Process or intermittent take-off methods.Yet, preferred continuous processing.Type to reactor does not have concrete restriction yet, can use the reactor of any kind, as the tubular reactor of the type of flowing through, fully mixed type stirred reactor, round-robin complete or have the reactor in pure hole.

The pyrolytic reaction of fourth aspect present invention is not by reactive distillation technology but substantially keeps carrying out under the condition of liquid phase.Although can use known Lewis acid or lewis-base catalyst, preferably do not use catalyzer, because use these catalyzer can cause coming from the ether of alcohol or the generation of alkene.

The condition of preferred decomposition reaction comprises the temperature of 120～280 ℃ (more preferably 140～240 ℃), and reaching from the fluid retention time that the liquid discharge amount is calculated is 0.5～50 hour (more preferably 1～20 hour).

Fourth aspect present invention is characterised in that at least 50% pyrolytic reaction product returns the production stage of (methyl) acrylate.Remaining pyrolytic reaction product discharges as pyrolysis residue, obtains waste or fuel.The position that the pyrolytic reaction product is returned does not have concrete restriction, as long as it is arranged in the production stage of (methyl) acrylate.Yet preferably at the bottom of the tower with product feed heavy constituent knockout tower, perhaps feed is in the thin-film evaporator of the reboiler that is used as the heavy constituent knockout tower.By like this pyrolytic reaction product being returned the production stage of (methyl) acrylate, most of (methyl) vinylformic acid, (methyl) acrylate and alcohol that is contained in as effective constituent in the pyrolytic reaction product, can be used as overhead product extraction from the heavy constituent knockout tower, be circulated to the reactions steps or the purification step of (methyl) acrylate, and reclaim.The ratio (hereinafter being referred to as " recycle ratio " sometimes) that preferably is back to the pyrolytic reaction product of (methyl) acrylate production stage and all pyrolytic reaction products is higher, because higher ratio can cause the amount of the resistates that will discharge less.In a fourth aspect of the present invention, at least 50%, preferred at least 80% pyrolytic reaction product is back to the production stage of (methyl) acrylate.Recycle ratio is high more, and the rate of recovery is just high more.Yet too high recycle ratio can cause the viscosity of resistates to increase and mobile the reduction.Therefore, the upper limit of recycle ratio is chosen to be operation and can continues the OK range of carrying out.Yet recycle ratio is generally 95% or lower.

Below in detail a fifth aspect of the present invention will be described in detail.Hereinafter, term (methyl) propenal is meant any in propenal and the Methylacrylaldehyde or two kinds.

(methyl) acrylate to fifth aspect present invention does not have concrete restriction.Yet preferred (methyl) acrylate that is made by the raw alcohol that does not have side chain is as (methyl) methyl acrylate, (methyl) ethyl propenoate, (methyl) n-butyl acrylate, the just own ester of (methyl) vinylformic acid, (methyl) vinylformic acid n-octyl, and (methyl) vinylformic acid methoxyl group ethyl ester.(methyl) n-butyl acrylate wherein most preferably.

The Michael addition adducts of fifth aspect present invention be the reactions steps of preparation (methyl) vinylformic acid and (methyl) acrylate or purification step at the by product that generates, and be the compound that the Michael addition of the compound with (methyl) acryl that exists in the preparation by (methyl) vinylformic acid, acetate, alcohol or water and acid or ester forms.The examples for compounds with (methyl) acryl that exists during the preparation comprises (methyl) propenal; (methyl) vinylformic acid; β-acryloxy propionic or Beta-methyl acryloxy isopropylformic acid (hereinafter the two is collectively referred to as dimer) that carboxylic acid forms as the Michael addition by (methyl) vinylformic acid self; (methyl) vinylformic acid tripolymer (tripolymer hereinafter) that forms by (methyl) vinylformic acid and dimeric Michael addition; and (methyl) vinylformic acid tetramer (tetramer hereinafter), and corresponding (methyl) acrylate that forms by these carboxylic acids with (methyl) acryl with pure esterification.The example also comprises the same compound that forms by the Michael addition of (methyl) vinylformic acid and (methyl) propenal.The specific examples of the Michael addition adducts of fifth aspect present invention comprises β-acryloxy propionic or Beta-methyl acryloxy isopropylformic acid and ester and aldehyde (β-acryloxy propionic aldehyde or Beta-methyl acryloxy isobutyric aldehyde); β-alkoxyl group propionic acid and ester thereof; Ethylene lactic acid or beta-hydroxy isopropylformic acid and ester and aldehyde; The dimer that these are sour, tripolymer, the tetramer etc.; Their ester; The form that β-acryloxy replaces, the form that β-acetoxyl group replaces, the form that β-alkoxyl group replaces, and the form of beta-hydroxy replacement; Or the like.

In a fifth aspect of the present invention; preferably the by product produced of (methyl) vinylformic acid comprises Michael addition adducts with the mixture of the by product of (methyl) acrylate production, and this Michael addition adducts is to form by alpha-position or β-position that water, alcohol or (methyl) vinylformic acid add to (methyl) acryl.

(methyl) vinylformic acid of preferred fifth aspect present invention is that the catalytic vapor phase oxidation by propane, propylene, propenal, iso-butylene, the trimethyl carbinol etc. obtains.Water cools off the gasiform oxidation reaction product rapidly.By adopt the azeotropic distn of entrainment agent, perhaps by the extraction process that adopt solvent carry out water/(methyl) acrylic acid separation thereafter.In addition, separate the low-boiling compound that comprises acetate, thereafter, separate the heavy constituent that comprise Michael addition adducts, obtain highly purified (methyl) vinylformic acid thus.Incidentally, water can separate by entrainment agent simultaneously with acetate.Michael addition adducts is with heavy constituent and high density accumulation.

The method of preparation (methyl) acrylate that can be used for fifth aspect present invention is identical with the method for second aspect present invention.

Identical according to the method for preparation (methyl) acrylate of fifth aspect present invention with method according to second aspect present invention.

The Michael addition adducts that generates as the main by product of esterif iotacation step, accumulate on the tower of the distillation tower that reclaims effective constituent with high density as heavy constituent at the bottom of.

In a fifth aspect of the present invention, the decomposition reaction of Michael addition adducts can be undertaken by any method in continuous processing, interrupter method, Semi-batch Process, the intermittent take-off method etc.Yet, preferred continuous processing.Type to reactor does not have concrete restriction yet, can use the reactor of any kind, as flow pattern reactor under flow through type tubular reactor, the film, mixes stirring-type reactor, circulation full mixing type reactor etc. entirely.The useful component that comprises in order to reclaim in the degradation production can use the method that during reaction obtains useful component by evaporation or distillation, also can use the method that obtains useful component after decomposition reaction by evaporation or distillation.Yet, in order to obtain high-recovery, preferred preceding a kind of method, i.e. reactive distillation technology.

Under the situation of using reactive distillation technology, reaction pressure greatly depends on temperature of reaction, and this will be described hereinafter.Under the pressure that is adopted, most useful component and most useful component such as vinylformic acid, acrylate and alcohol that is contained in the decomposition reaction feed, all gasifications that generate by decomposition reaction.

Catalyzer is selected from mineral acid such as sulfuric acid and phosphoric acid, organic acid such as methylsulfonic acid and tosic acid etc.Yet, preferred organic acid.

In a third aspect of the present invention, the concentration of acid catalyst is 0.1～1.0% weight, is preferably 0.2～0.8% weight, based on feed liquid.

The temperature of decomposition reaction is preferably 120～200 ℃.The fluid retention time of calculating from the liquid discharge amount is preferably 0.5～50 hour, particularly 2～20 hours.Under the situation that decomposition reaction is carried out continuously, the fluid retention time of calculating from the liquid discharge amount can be considered as the reaction times.For example, when the liquid capacity of reactor is 500L, and the liquid discharge amount is when being 100L/H, and then the time of storing is 5 hours.

Incidentally, the common decomposition reaction condition that is adopted up to now comprises: the concentration of tosic acid counts 5～15% by the weight of feed liquid, and the temperature of decomposition reaction is 180～230 ℃, and the reaction times is 0.1～4.0 hour.The inventor from a plurality of angle analysis generate the reaction of ether by product and the decomposition reaction of Michael addition adducts, and find to be catalyzer and to adopt lower decomposition temperature to help suppressing the generation of ether by product with the acid of lower concentration.In addition, the Michael addition adducts that is created on (methyl) vinylformic acid production stage is handled in expection simultaneously, can produce existing vinylformic acid and oligopolymer thereof and reduce the effect that the ether by product generates, and sees JP-A-9-183752 and JP-A-9-183753 for details.And, together handle (methyl) acrylic acid Michael addition adducts and also have such advantage, promptly the amount of the mixture of unit time processing can increase, and then improves the flow velocity by pipeline, particularly promotes the discharging of high viscosity resistates.

When the decomposition reaction condition that adopts according to fifth aspect present invention, the decomposition reaction process of Michael addition adducts is slack-off a little.Yet, when the reaction times extends to a certain degree, can obtain the sufficiently high rate of recovery.

All reclaim the overhead product that is rich in (methyl) vinylformic acid, (methyl) acrylate and alcohol that obtains by decomposition reaction, and send it to the production stage of acrylate.Although the recovery position to this overhead product does not have concrete restriction, preferably the overhead product that is reclaimed is sent to the step that is not positioned at the light constituent after separating, because overhead product comprises a spot of light constituent.One of major advantage of fifth aspect present invention is, because being obtained from the heavy constituent of (methyl) vinylformic acid production stage and (methyl) acrylate production stage can handle together as by product, but also because the valuable material that is reclaimed can only be sent to the production stage of (methyl) acrylate, so can simplify technology, and by reduction engineering cost, operator and common plant cost, and raise the efficiency widely.

＜embodiment 〉

Now, illustrate in greater detail the present invention with reference to embodiment.

Embodiment 1

As shown in Figure 1, be equipped with in the methyl acrylate production stage thin-film evaporator as the tower bottom distillate of the heavy constituent knockout tower of reboiler as feed material, send decomposition reaction to.Consisting of of tower bottom distillate: the vinylformic acid of 19% weight, the ethylene lactic acid of 1% weight, the ethylene lactic acid methyl esters of 7% weight, β-the acryloxy propionic of 8% weight, the β of 6% weight-acryloxy propionic methyl esters, the 'beta '-methoxy propionic acid of 40% weight, the 'beta '-methoxy methyl propionate of 11% weight, and the heavy constituent of 8% weight and other material.With tower bottom distillate with 865kg/ hour feed in decomposition reactor.Decomposition reactor is the stirred reactor of being made by Hastelloy (Hastelloy) C, and internal diameter is 1000mm, highly is 2000mm, and thermal medium offers external jacket, temperature of reaction is adjusted to 200 ℃.Adjust the fluid retention time by the liquid level in the control decomposition reactor.Reaction pressure remains 500kPa, and this is to keep the required pressure of liquid phase.Be adjusted to 800kg/ hour respectively and 65kg/ hour with being circulated to the speed of reboiler of heavy constituent knockout tower and the discharge rate of resistates, so the time of storing of being calculated by the liquid discharge amount is 10 hours.Operation can stably continue more than 3 months, and does not cause line clogging or other problem.Composition by the gas chromatographic analysis resistates, its result is: the water of 0.6% weight, the methyl alcohol of 10% weight, the methyl acrylate of 11% weight, the vinylformic acid of 44% weight, the ethylene lactic acid of 0.4% weight, the ethylene lactic acid methyl esters of 4% weight, the β-acryloxy propionic of 2% weight, the β of 1% weight-acryloxy propionic methyl esters, the 'beta '-methoxy propionic acid of 14% weight, the 'beta '-methoxy methyl propionate of 4% weight, and the heavy constituent of 9% weight and other material.

Embodiment 2

Be equipped with in the methyl acrylate production stage thin-film evaporator as the tower bottom distillate of the heavy constituent knockout tower of reboiler as feed material, send decomposition reaction to.Consisting of of tower bottom distillate: the vinylformic acid of 20% weight, the ethylene lactic acid of 1% weight, the ethylene lactic acid methyl esters of 8% weight, β-the acryloxy propionic of 8% weight, the β of 7% weight-acryloxy propionic methyl esters, the 'beta '-methoxy propionic acid of 41% weight, the 'beta '-methoxy methyl propionate of 12% weight, and the heavy constituent of 3% weight and other material.With tower bottom distillate with 150kg/ hour feed in decomposition reactor.Decomposition reactor is the stirred reactor of being made by Hastelloy (Hastelloy) C, and internal diameter is 1000mm, highly is 2000mm, and thermal medium offers external jacket, temperature of reaction is adjusted to 200 ℃.Reaction pressure remains 130kPa.Be filled to tower and the condenser of 2000mm at the top of stirred reactor connection internal diameter 400mm, height 4000mm and filler, so that carry out decomposition reaction by reactive distillation technology.Adjust the fluid retention time by the liquid level in the control decomposition reactor, make that the time of storing of being calculated by the liquid discharge amount is 10 hours.As a result, after moving 1 month continuously, blockage problem has taken place, and therefore operation stops in the downstream of discharge tube.The discharge rate average out to of resistates is 76kg/ hour around here.Composition by the gas chromatographic analysis resistates, its result is: the water of 0.2% weight, the methyl alcohol of 0.2% weight, the methyl acrylate of 0.3% weight, the vinylformic acid of 39% weight, the ethylene lactic acid of 0.3% weight, the ethylene lactic acid methyl esters of 7% weight, the β-acryloxy propionic of 4% weight, the β of 4% weight-acryloxy propionic methyl esters, the 'beta '-methoxy propionic acid of 31% weight, the 'beta '-methoxy methyl propionate of 8% weight, and the heavy constituent of 6% weight and other material.

The result of embodiment 1 and embodiment 2 clearlys show: in the time will being applied to from the Michael addition adducts of acrylate purification step in extraction according to the decomposition reaction of second aspect present invention, not only the rate of recovery of effective constituent can be higher than employed up to now reaction distillation method, and resistates also comprises the light constituent of larger proportion.Resistates thereby have the enhanced flowability makes and can avoid blockage problem and realize continuing and stable operation.

Embodiment 3

Make the tower bottom distillate of rectifying tower in the n-butyl acrylate production stage carry out decomposition reaction.

The tower bottom distillate of the rectifying tower of n-butyl acrylate has following composition: the n-butyl acrylate of 16% weight, the β of 59% weight-n-butoxy n-butyl propionate, the positive butyl ester of the β-acryloxy propionic of 4% weight, the positive butyl ester of the ethylene lactic acid of 2% weight, and the heavy constituent of 19% weight and other material.With tower bottom distillate with 580g/ hour feed in decomposition reactor.

The internal diameter of decomposition reactor is 200mm, and length is 400mm, and is made by Hastelloy C.The distillation tower that internal diameter 30mm, length 1000mm and ring packing are filled to 500 mm is housed above the reactor, and accessory condenser and vacuum system.With external heater regulate decomposition reactor temperature of reaction.Adjust the fluid retention time by the liquid level in the control decomposition reactor.

Provide tosic acid with 2.9g/ hour (0.5% weight is based on feed liquid),, and under the time that stores of the reaction pressure of 47kPa, 160 ℃ decomposition temperature and 10 hours, carry out decomposition reaction as cleavage reaction catalyst.

The composition of the resistates of at the bottom of tower, discharging by gas chromatographic analysis, its result is: the n-butyl acrylate of 6% weight, the β of 36% weight-n-butoxy n-butyl propionate, the positive butyl ester of the acryloxy propionic of 2% weight, the positive butyl ester of the ethylene lactic acid of 0.3% weight, the tosic acid of 1.4% weight, and the heavy constituent of 54% weight and other material.The acquisition speed of this reaction residue is 199.8g/ hour.Determine that this reaction residue has high workability.

Reclaimed overhead product by cat head with 382.5g/ hour, it comprises vinylformic acid, n-butyl acrylate and propyl carbinol as main component.It comprises the di-n-butyl ether of 0.35% weight.

Embodiment 4

Adopt and embodiment 3 identical feed material and equipment, different is provides (5% weight is based on feed liquid) as the tosic acid of catalyzer with 290g/ hour speed.Feed material was with 5.80kg/ hour speed charging.Decomposition reaction is 200 ℃ in temperature of reaction, and pressure is 120kPa, and the time of storing is to carry out under 1 hour the reaction conditions.

As a result, reaction residue obtains at the bottom of tower with 2.41kg/ hour V-bar.This reaction residue has the flowability slightly poor than embodiment 3.Consisting of of reaction residue: the n-butyl acrylate of 4% weight, the β of 34% weight-n-butoxy n-butyl propionate, the positive butyl ester of the acryloxy propionic of 2% weight, the positive butyl ester of the ethylene lactic acid of 0.3% weight, the tosic acid of 12% weight, and other material of 48% weight.

By the cat head of the distillation tower above the decomposition reactor, obtain overhead product with average 3.68kg/ hour speed, this overhead product comprises vinylformic acid, n-butyl acrylate and propyl carbinol and wants composition as group.It comprises the di-n-butyl ether of 2.78% weight.

Embodiment 5

Utilize the decomposition reactor identical with embodiment 3, make the tower bottom distillate that is used for the isolating rectifying tower of heavy constituent in the methyl acrylate production unit, under the pressure of 60kPa, utilize catalyst type, concentration, temperature and the fluid retention time identical to carry out decomposition reaction with embodiment 3.Consisting of of feed material: the vinylformic acid of 20% weight, β-the acryloxy propionic of 8% weight, the 'beta '-methoxy methyl propionate of 12% weight, the ethylene lactic acid methyl esters of 7% weight, the 'beta '-methoxy propionic acid of 40% weight, the β of 7% weight-acryloxy propionic methyl esters, and other material of 6% weight.Its input speed is 580g/ hour.

As a result, the distillation tower cat head above decomposition reactor obtains reclaiming liquid with 397g/ hour V-bar.Capture 0.72g/ hour dimethyl ether with acetone-dry ice trap.

Embodiment 6

Utilize with embodiment 5 identical feed material and decomposition reactor and carry out decomposition reaction, different is catalyst concn, temperature of reaction, the fluid retention time, and reaction pressure becomes 5% weight (based on feed material), 200 ℃ respectively, 1 hour, and 180kPa.Distillation tower cat head above decomposition reactor obtains reclaiming liquid with 3.87kg/ hour V-bar.Capture 68.1g/ hour dimethyl ether with acetone-dry ice trap.

By 4 of embodiment 3 and embodiment relatively reach relatively can clearly be seen that of 6 of embodiment 5 and embodiment, the inlet amount by regulating acid catalyst can suppress the generation of ether compound to specific scope.

Embodiment 7

Rectifying tower (heavy constituent knockout tower) tower bottom distillate with the Michael addition adducts of the methyl acrylate that comprises high density composed as follows, and be used as feed material from vinylformic acid rectifying tower and tower bottom distillate composed as follows in the vinylformic acid production stage, to carry out pyrolytic reaction.Incidentally, heating-surface area is housed is 2000cm to the methyl acrylate rectifying tower ²Thin-film evaporator, as reboiler.

The composition of the tower bottom distillate of＜methyl acrylate rectifying tower 〉

Vinylformic acid: 20% weight

Ethylene lactic acid methyl esters: 7% weight

β-acryloxy propionic: 8% weight

β-acryloxy propionic methyl esters: 7% weight

'beta '-methoxy propionic acid: 40% weight

'beta '-methoxy methyl propionate: 12% weight

Heavy constituent and other material: 6% weight

The composition of the tower bottom distillate of＜vinylformic acid rectifying tower 〉

Vinylformic acid: 21% weight

β-acryloxy propionic: 51% weight

Heavy constituent and other material: 28% weight

As pyrolysis reactor, use stirred reactor that make by Hastelloy C, internal diameter 200, height 400mm.Thermal medium is offered external jacket, so that temperature of reaction is adjusted to 200 ℃.Regulate the fluid retention time by the liquid level in the control pyrolysis reactor.Reaction pressure remains 500kPa, and this is to keep the required pressure of liquid phase.

In pyrolysis reactor, speed is 500g/ hour with the tower bottom distillate feed of the tower bottom distillate of methyl acrylate rectifying tower and vinylformic acid rectifying tower.Starting stage in operation is stored reaction product, then with such proportional part offer the thin-film evaporator of methyl acrylate rectifying tower, feasible reaction product of whenever discharging and being sent to 1 weight part outside the system from pyrolysis reactor, internal circulating load is 13 weight parts.This thin-film evaporator is worked under the temperature of the pressure of 9.3kPa and 120 ℃, and distillation residue be added to two kinds of feed material (from two kinds of tower bottom distillates of each rectifying tower) and offer pyrolysis reactor.

Therefore total system is stablized, and the time of storing that will be come by the calculating of liquid discharge amount in the pyrolysis reactor is adjusted to 10 hours.

As a result, the speed that is circulated to the thin-film evaporator of methyl acrylate rectifying tower is 3.9kg/ hour, and the discharge rate of resistates is 300g/ hour (circulation ratio=92.9%).Stably obtain about 700g/ hour overhead product by thin-film evaporator.Operation can stably continue 3 months, and any problem such as line clogging problem do not occur.

From the composition of system at the resistates that emits, the result is as follows by gas chromatographic analysis.

The composition of＜resistates 〉

Water: 0.5% weight

Methyl alcohol: 6% weight

Methyl acrylate: 7% weight

Vinylformic acid: 56% weight

Ethylene lactic acid methyl esters: 1% weight

β-acryloxy propionic: 6% weight

β-acryloxy propionic methyl esters: 1% weight

'beta '-methoxy propionic acid: 5% weight

'beta '-methoxy methyl propionate: 2% weight

Heavy constituent and other material: 16% weight

In other words, the rate of recovery of valuable material (amount that is reclaimed/provided all heavy constituent) is 70% weight.

In addition, continuous service is after 3 months, the dimethyl ether of analyzing and weighing and catch by the dry ice-propanone trap that places vacuum pipeline.Its amount is 1.8g as a result.

Embodiment 8

Two kinds of tower bottom distillates that will be identical with embodiment 7 are as feed material, separately with 75kg/ hour speed feed in reactor.As reactor, use stirred reactor that make by Hastelloy C, internal diameter 1000mm, height 2000mm.Thermal medium is offered external jacket, temperature of reaction is adjusted to 200 ℃.Reaction pressure remains 130kPa.In addition, internal diameter is installed is 400mm on stirred reactor top, highly be tower and the condenser that 4000mm and filler are filled to 2000mm, to carry out decomposition reaction by reactive distillation technology.Adjust the fluid retention time by the liquid level in the control decomposition reactor, make that the time of storing of being calculated by the liquid discharge amount is 10 hours.

As a result, the slight obstruction takes place in the downstream of discharge tube in one month by a definite date continuous service, but can utilize bypass (by-pass) pipeline to deal with.Around here, the discharge rate average out to of resistates is 55kg/ hour.Utilize the composition of gas chromatographic analysis resistates, its result is as follows.

The composition of＜resistates 〉

Water: 0.2% weight

Methyl alcohol: 0.1% weight

Methyl acrylate: 0.2% weight

Vinylformic acid: 15% weight

Ethylene lactic acid methyl esters: 3% weight

β-acryloxy propionic ester: 18% weight

β-acryloxy propionic methyl esters: 3% weight

'beta '-methoxy propionic acid: 14% weight

'beta '-methoxy methyl propionate: 4% weight

Heavy constituent and other material: 43% weight

In other words, the rate of recovery of valuable material (yield/provided all heavy constituent) is 63% weight.

Embodiment 7 clearly illustrates that with the result of embodiment 8: with still compare so far at the reactive distillation process that uses, the method according to this invention not only can improve the rate of recovery of effective constituent, and also comprises the light constituent of larger proportion in the resistates.Resistates mobile thereby be enhanced is so can avoid blockage problem and realize stable and lasting operation.

Embodiment 9

Use the reactor identical with embodiment 7.Connect distillation tower and accessory condenser, vacuum system and acetone-dry ice trap that internal diameter 30mm, length 1000mm and ring packing are filled to 500mm on the top of reactor.Two kinds of tower bottom distillates that will be identical with the feed material among the embodiment 7 separately with 290g/ hour speed feed in reactor.As decomposition catalyst, its amount is counted 5% weight by feed material with tosic acid.Decomposition reaction was carried out 24 hours under the reaction pressure of 160 ℃ temperature of reaction and 60kPa, and the time of storing of being calculated by the liquid discharge amount is 10 hours.

Obtain average out to 396g/ hour recovering liquid through the distillation tower cat head above the decomposition reactor.The V-bar that acetone-thousand ice trap captures dimethyl ether is 3.8g/ hour.

The result of embodiment 7 and embodiment 9 clearly illustrates that: by mainly carrying out pyrolytic reaction and further regulate acid catalysis dosage in specified range in liquid phase, not only can improve the rate of recovery of effective constituent, and can suppress to come from the generation of the ether of methyl alcohol significantly.

Embodiment 10

Make the tower bottom distillate of the rectifying tower of separating heavy in the tower bottom distillate of rectifying tower in the n-butyl acrylate production stage and the vinylformic acid production stage carry out decomposition reaction.

The tower bottom distillate of n-butyl acrylate rectifying tower has following composition: the n-butyl acrylate of 16% weight, the β of 59% weight-n-butoxy n-butyl propionate, the positive butyl ester of the β-acryloxy propionic of 4% weight, the positive butyl ester of the ethylene lactic acid of 2% weight, and other heavy constituent of 19% weight.This feed material with 290g/ hour speed feed in decomposition reactor.

The tower bottom distillate of rectifying tower that is used for the heavy constituent of separation of propylene acid has following composition: the vinylformic acid of 21% weight, the β-acryloxy propionic of 51% weight, and other heavy constituent of 28% weight.This feed material with 290g/ hour speed feed in decomposition reactor.

The internal diameter of decomposition reactor is 200mm, and length is 400mm, and is made by Hastelloy C.On the top of reactor internal diameter being installed is that 30mm, length are distillation tower and accessory condenser and the vacuum system that 1000mm and ring packing are filled to 500mm.Temperature of reaction in the decomposition reactor is regulated with external heater.Adjust the fluid retention time by the liquid level in the control decomposition reactor.

Provide tosic acid with the speed of 2.9g/ hour (0.5% weight is based on feed liquid), and 10 hours storing the time carried out in decomposition reaction under the decomposition pressure of the reaction pressure of 47kPa and 160 ℃ as cleavage reaction catalyst.

The composition of the resistates that at the bottom of tower, discharges by gas chromatographic analysis, its result is as follows: the vinylformic acid of 8.4% weight, the propyl carbinol of 1.0% weight, the n-butyl acrylate of 5.1% weight, the β of 18.3% weight-n-butoxy n-butyl propionate, the positive butyl ester of the β-acryloxy propionic of 1.3% weight, the positive butyl ester of the ethylene lactic acid of 0.7% weight, β-the acryloxy propionic of 11.7% weight, the tosic acid of 1.4% weight, and other heavy constituent of 52.1% weight.This reaction residue obtains with 199g/ hour speed.

Through recovered overhead 383g/ hour overhead product, it comprised the water of 0.13% weight, the vinylformic acid of 46.2% weight, the n-butyl acrylate of 33.2% weight, the propyl carbinol of 13.0% weight, and other material of 7.3% weight.It comprises the di-n-butyl ether of 0.15% weight.

Embodiment 11

Utilize and embodiment 10 identical equipment, the tower bottom distillate as the n-butyl acrylate rectifying tower of unique feed material is carried out the decomposition reaction experiment.Identical among this feed material and the embodiment 10, and carry out decomposition reaction with 580g/ hour input speed.Other condition and embodiment 10 are identical.The composition of the resistates that at the bottom of tower, discharges by gas chromatographic analysis, its result is: the n-butyl acrylate of 6% weight, the β of 36% weight-n-butoxy n-butyl propionate, the positive butyl ester of the acryloxy propionic of 2% weight, the positive butyl ester of the ethylene lactic acid of 0.3% weight, the tosic acid of 1.4% weight, and other material of 54.3% weight.This reaction residue obtains with 199.8g/ hour speed.

Through recovered overhead 382.5g/ hour overhead product, it comprised vinylformic acid, n-butyl acrylate, and propyl carbinol is a main component.It comprises the di-n-butyl ether of 0.35% weight.

Can determine from the result of embodiment 10 and embodiment 11, even handle the heavy constituent that derive from the vinylformic acid production stage and comprise the high density Michael addition adducts simultaneously, valuable material can be reclaimed satisfactorily equally, and the generation of di-n-butyl ether by product can be suppressed.

Embodiment 12

Use and embodiment 10 identical feed material, just provide as the tosic acid of catalyzer speed with 290g/ hour (5% weight is based on feed liquid).Feed material was with 5.80kg/ hour speed charging.Decomposition reaction is 200 ℃ in temperature of reaction, and pressure is 120kPa, and the time of storing is to carry out under 1 hour the condition.

As a result, reaction residue obtains at the bottom of tower with average 2.3kg/ hour speed.Distillation tower above decomposition reactor is recovered to overhead product with average 3.8kg/ hour speed, and it comprises vinylformic acid, n-butyl acrylate and propyl carbinol as main component.It comprises the di-n-butyl ether of 1.54% weight.

Embodiment 13

Use and embodiment 10 identical decomposition reactors.Feed material is by mixing the tower bottom distillate of the rectifying tower that is used for separating heavy in the methyl acrylate production unit with 1: 1 ratio of mixture and the heavy constituent (tower bottom distillate of rectifying tower) of vinylformic acid production unit prepare, and utilize it under the pressure of 60kPa, carry out decomposition reaction with catalyst type, concentration, temperature and the fluid retention time identical with embodiment 10.Consisting of of feed material: the vinylformic acid of 21% weight, β-the acryloxy propionic of 30% weight, the 'beta '-methoxy methyl propionate of 6% weight, the ethylene lactic acid methyl esters of 4% weight, the 'beta '-methoxy propionic acid of 21% weight, the β of 4% weight-acryloxy propionic methyl esters, and other heavy constituent of 14% weight.Its input speed is 580g/ hour.

As a result, the recovering liquid average out to that obtains of the distillation tower cat head above decomposition reactor is 396g/ hour.With the dimethyl ether that acetone-the dry ice trap traps is 0.35g/ hour.

Embodiment 14

Utilize with embodiment 13 identical feed material, decomposition reactor and reaction conditions and carry out decomposition reaction, different is that catalyst concn becomes 5% weight, based on the feed material amount.The recovering liquid average out to that distillation tower cat head above decomposition reactor obtains 397g/ hour.With the dimethyl ether that acetone-the dry ice trap traps is 3.8g/ hour.

Although with reference to its specific embodiments in detail the present invention has been described in detail, it will be apparent to those skilled in the art that and wherein can make various substitutions and modifications and do not break away from its design and scope.

The Japanese patent application (application number is 2001-362895) that the application submitted to based on November 28 calendar year 2001, the Japanese patent application (application number is 2001-362896) that submit to November 28 calendar year 2001, the Japanese patent application (application number is 2001-362897) that submit to November 28 calendar year 2001, and the Japanese patent application (application number is 2001-392057) of submission on December 25 calendar year 2001, their full content is incorporated herein by reference.

＜industrial applicibility 〉

As mentioned above, according to first and second aspects of the present invention, pyrolysis is as (methyl) acrylic acid chemical combination Accessory substance in thing or (methyl) acrylate production stage and the Michael addition adducts that generates thus can Reclaim (methyl) acrylate with high-recovery. In addition, (methyl) acrylate can stably prepare, And do not cause blockage problem in the technology. According to a third aspect of the invention we, as (methyl) acrylate Accessory substance in the production stage and the Michael addition adducts that generates can utilize acid to carry out as catalyst Resolution process, and then with high-recovery recovery (methyl) acrylic acid, (methyl) acrylate and alcohol. In addition, Can also suppress the generation of accessory substance ether, described accessory substance ether can bring technology and/or product quality problem. According to a forth aspect of the invention, it is the method for the accessory substance of decomposition (methyl) acyclic compound production, Wherein decompose the step of the accessory substance that (methyl) acrylic acid produces and the pair that decomposition (methyl) acrylate is produced The step of product can two combine into one, thereby bring significant economic benefit, builds into reduction as saving Basis and energy. In addition, can stably reclaim (methyl) acrylic acid, (methyl) acrylate by high-recovery And alcohol, suppress simultaneously to come from the ether of alcohol or the generation of olefin by-products. According to a fifth aspect of the invention, Generate as the accessory substance in (methyl) acrylic acid production stage and (methyl) acrylate production stage The Michael addition reaction product can utilize acid together to carry out resolution process as catalyst, thereby with height The rate of recovery reclaims (methyl) acrylic acid, (methyl) acrylate and alcohol. In addition, can suppress accessory substance ether Generation, this accessory substance ether bring problem can for technology and/or product quality. According to the 5th side of the present invention Face, each step of the decomposition reaction of Michael addition adducts can integrate, thereby brings significant warp The Ji benefit is as energy-conservation and reducing the construction costs and utility cost.

Claims (10)

1. method for preparing (methyl) acrylate, this method comprises:

Generate the reactions steps of (methyl) acrylate; And

The by product pyrolysis that to from generate step, separate, therefrom reclaiming the step of (methyl) acrylate,

It is characterized in that described pyrolytic reaction comes down to carry out in liquid phase; And

At least 50% pyrolytic reaction product returns step upstream.

2. according to the method for preparation (methyl) acrylate of claim 1, the by product that it is characterized in that the formation reaction of described (methyl) acrylate is the tower bottom distillate that is used for the distillation tower of separating heavy in the purification step of (methyl) acrylate of generating of purifying.

3. according to the method for preparation (methyl) acrylate of claim 2, it is characterized in that described distillation tower is equipped with thin-film evaporator as reboiler.

4. according to the method for each preparation (methyl) acrylate in the claim 1～3, the reaction that it is characterized in that generating (methyl) acrylate is (methyl) vinylformic acid and the esterification of alcohol and/or (methyl) acrylate transesterification reaction with alcohol.

5. according to the method for preparation (methyl) acrylate of claim 4, it is characterized in that described alcohol is methyl alcohol, ethanol or butanols.

6. according to the method for each preparation (methyl) acrylate in the claim 1～5, it is characterized in that the by product of described (methyl) acrylate formation reaction comprises Michael addition adducts.

7. according to the method for preparation (methyl) acrylate of claim 6, it is characterized in that described Michael addition adducts is by water, alcohol or (methyl) vinylformic acid are added to the compound that forms on the acryl.

8. according to the method for each preparation (methyl) acrylate in the claim 1～7, the temperature that it is characterized in that pyrolytic reaction is 120～280 ℃.

9. according to the method for each preparation (methyl) acrylate in the claim 1～8, the cycle that it is characterized in that pyrolytic reaction is 0.5～50 hour.

10. according to the method for each preparation (methyl) acrylate in the claim 1～9, it is characterized in that at least 80% pyrolytic reaction product returns step upstream.

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