CN1255116A

CN1255116A - Process for producing maleic acid

Info

Publication number: CN1255116A
Application number: CN 98804885
Authority: CN
Inventors: C·德特洛夫; S·巴巴利诺
Original assignee: Procter and Gamble Co
Current assignee: Procter and Gamble Co
Priority date: 1997-03-11
Filing date: 1998-03-06
Publication date: 2000-05-31
Also published as: BR9808658A; AR011188A1; CA2283206C; JP2001514656A; CO5031274A1; CA2283206A1

Abstract

The present invention relates to a process for producing maleic acid with close control of the temperature for optimum conversion of maleic anhydride into maleic acid and minimal production of fumaric acid.

Description

The method for preparing toxilic acid

Invention field

The present invention relates to produce the method for preparing toxilic acid of few fumaric acid.

Background of invention

At toxilic acid known in the art (MA) is the hydrolysis reaction product of maleic anhydride (MAH).Typical example is described in the 778th page of Encyclopedia ofChemical Technology the 14th volume of the third edition of Kirk-Othmer, and the process that wherein prepares MA is at room temperature carried out.MAH is usually with solid-state adding.But be to obtain slow speed of reaction at room temperature with the problem that solid-state MAH ran into.Another problem of using solid-state MAH to run into is to be difficult to handle when industrial scale applications.Really, compare with liquid MAH, solid-state MAH is difficult to pumping, storage and accurately metering.

A method that addresses this problem is to carry out the production of MA in batches, is about to MAH and joins in the hot water.But, although this solution provides effective speed of reaction,, will also give birth to undesirable volume production as the fumaric acid of by product because thermopositive reaction and the temperature that causes raise, it accounts for more than 0.4% of resultant reaction mixture weight.

Really, because the reaction between MAH and the water is thermopositive reaction, temperature in reactor and the therefore temperature rising of reaction mixture.The rising of this temperature is suitable for the formation of fumaric acid rather than MA.Fumaric acid is a kind of disagreeable by product to a certain extent, because it at room temperature is easy to precipitate down as 0.4% (weight) at lower concentration.In addition, when being blended into cleaning compositions, having been found that with the composition that contains MA and compare that fumaric acid has lower limescale and removes usefulness.

Therefore, a target of the present invention provides the method that the best MAH of having of few output fumaric acid becomes the transformation efficiency of MA.

Now unexpectedly, discovery uses substantially invariable temperature to address that need from the whole process of preparation of the recovery that touches MA of reagent.

The present invention's summary

The present invention relates to prepare from maleic anhydride and water the method for toxilic acid, it comprises the following steps:

A). maleic anhydride is contacted the formation reaction mixture with water;

B). reclaim toxilic acid from described reaction mixture; With

Be characterised in that, at step a) and b) described in reaction mixture be maintained at a substantially invariable temperature between 52-85 ℃.

Fig. 1 has shown the formation of the production unit that is applicable to the inventive method.

Detailed description of the present invention Raw material

1) maleic anhydride

MAH is a solvent of the inventive method. Preferably use in the methods of the invention The melting form is that temperature is higher than 52 ℃ MAH. The temperature of the preferred MAH that uses in this Be 55-70 ℃, more preferably 65 ℃.

2) water

Water is the Another essential component of the inventive method. Really, water can make the MAH hydrolysis Become MA. Preferably, the adding of water is carried out according to the stoichiometric amount to MAH. Also often make Obtain the liquid solution of MA with excessive water. In general, water is 15-60 ℃ temperature Lower adding. Another advantage that makes water in the inventive method is also to can be used as to guarantee whole mistake The substantially invariable means of holding temperature in the journey.The control of temperature

Because the reaction between MAH and the water is thermopositive reaction, temperature controlling is an essential characteristic of the present invention really.Really, if temperature is uncontrolled because thermopositive reaction raises, will be suitable for the formation of fumaric acid.The applicant finds unexpectedly that in the reaction of described production method, use the toxilic acid (MA) that basic constant temp can produce high yield, the yield of fumaric acid is then extremely low.The toxilic acid of high yield is meant 99% the yield that is at least reaction mixture weight.At step a) and b) in, the temperature in the reaction process should keep constant and in 52-85 ℃ scope.The set following fusing point that is limited to maleic anhydride.Really, be lower than this temperature, MAH is solid-state, if use solid-state MAH will cause the unnecessary long reaction times (more than 1 hour).On the other hand, the upper limit is set to avoid unnecessary steam by industrial practice.Really, because the cavitation that steam comes out and pipeline is interior can be damaged pump, so steam can cause the dangerous of operating process.

For the present invention, the temperature of whole production reaction preferably in 55-70 ℃ scope, more preferably 65 ℃.Substantially constant is meant that the temperature deviation with its original value is no more than 3 ℃.Higher temperature or higher temperature deviation can not be used hereinto, because this will cause the yield of fumaric acid to reach unacceptable level.Unacceptable yield is meant and is higher than 0.4% (weight).The yield of preferred fumaric acid is not higher than 0.1% of resultant reaction mixture weight.

The control of temperature reaction can be undertaken by several approach, such as by placing the heat exchanger around the reactor and/or being undertaken by the temperature of control water inlet.For the present invention, substantially invariable temperature controlling is preferably undertaken by joining the water of producing reaction.Really, by changing the temperature of water inlet, the control of temperature reaction can be maintained at substantially constant.

Contacting of MAH and water relates to vigorous stirring, thereby reaches the tight contact between the reagent.For batch system, preferably in several minutes, can be full of the pump purt ability of the agitator of reactor, for example the top enters waterleaf or adjustable vane agitator.But, for technical scale, preferred continuous processing.Can be for reference be that the technical scale of indication is meant for the MA aqueous solution of 40% (weight) the reactor throughput of at least 100 kilograms/hours efficient recovery MA here.From the permanent viewpoint of calculating of material, this equals at least 33.6 kilograms/hours MAH charging and at least 66.3 kilograms/hours water inlet.Preferred used hereinto reactor has 8 to 12 tons/hour throughput, most preferably has the throughput of the recovery MA aqueous solution of 10 tons of/hour 40% (weight) activity.At this moment, stirring will be depended on the pump rate that passes in and out reactor and be defined, thereby make the pump purt ability high order of magnitude of mixing time than reactor.For example, if the pump purt ability of turnover reactor is 10 tons/hour, then stirring capacity is about 100 tons/hour.

Other method also can be chosen use wantonly, and further controlling and/or prevent may be because the thermopositive reaction of MAH and water forms fumaric acid.

One of preferred optional method is that constant speed enters MAH in the whole production reaction.Add by constant speed, the control of temperature of reaction is simplified, because only need regulate temperature control agent such as water temperature for keeping the constant temperature of reaction.The constant speed adding of this MAH is advantageously used in industrial process such as in the continuous processing, because reaction is actual in the stable state operation, has not both had the accumulation of MA quality also not have the loss of MA quality and only need do little adjusting to temperature regulating device (agent) according to this.

Another kind of preferred optional method is to carry out described production reaction in the presence of the prefabricated MA bigger than MAH and the water yield.By using this relatively large prefabricated MA, the negative effect of thermopositive reaction since during beginning with regard to existence that prefabricated MA is arranged and diluted, fortune provides the inertia that dramatic temperature is changed.Like this, diluted because the local temperature that thermopositive reaction causes raises according to this.This can be by at first placing reactor to reach prefabricated MA before reaction process begins.Relatively large being meant here can allow reaction carry out 10 minutes to the 1 hour also concentration of preferred 30 minutes time.In general, the used concentration of prefabricated MA is 20-60% (weight) in water, is preferably 35-45% (weight); The latter is particularly preferred for industrial production.The concentration of the prefabricated MA of 40 (weight) % is most preferred in reaction mixture.Described prefabricated MA can be the MA that purchases or or even prepare by crystallization MAH is dissolved in the water.Used prefabricated MA preferably has the fusing point that is higher than MAH but is not higher than 85 ℃ temperature in this before the reaction beginning, because the temperature more than 85 ℃ is suitable for being transformed into fumaric acid.

More preferably the concentration of MA (promptly produce with ready-formed MA) should keep substantially constant in reaction mixture in reaction process of the present invention.Substantially constant be meant the variation of concentration be no more than the original start value 3%, preferably be no more than 1%.Preferred original start value be the concentration of prefabricated MA be reaction mixture weight 20-60%, be preferably 35-45%.The MA concentration of 40% (weight) is most preferred in reaction mixture.Really, this concentration has been avoided the precipitation of MA under normal storage and the transport condition.Constant density is by guaranteeing that the permanent calculation of the material in the mixture described in the reaction process always is in stable state (being exactly the not also not loss of accumulation of quality of MA) and obtains.The permanent control of calculating of this stable state material can use standard industry under meter (for example Danfoss mass flowmeter), level control (for example Vega Radar LT) and control loop (PLC 5/40 AllenBradley that for example has operator interface therewith in actuating type 3.51 systems) to obtain.The permanent optimal way of calculating of a kind of control stabilization attitude material is that the feed rate with water and MAH is set in its target level, and by regulating the flow controlling reactor level that effluxes of MA solution.

Because above-mentioned reason, MA preferably stores (if desired) to avoid the crystallization of MA with the concentration that is higher than its solubility curve, for example stores with the concentration of 40% (weight) MA, and preferred storage temperature is 40 ℃.

As mentioned above, an advantage of the inventive method is the continuous processing that is applicable to that reagent and product add and derive continuously.Do not need stopped reaction because carrying out the continuous preparation of MA, so such method is applicable to industrial production.Another advantage of this method is that it has been avoided long-time and uneconomic startup and has closed step.

A kind of preferred embodiment of carrying out the inventive method is continuous flow stirred-tank reactor (CFSTR).CFSTR knows and is described in the 882nd to 883 page of Encyclopedia of Chemical Technology the 19th volume of the Kirk-Othmer of the third edition for those skilled in the art. CFSTR

By using this device, can in reactor, carry out the control of temperature reaction, the control of toxilic acid constant density and the control of reagent flow.

The control of MA constant density obtains by the MA of recovery with two kinds of charging equals in quality in reactor, guarantees permanent calculation of stable state material in reactor according to this, does not promptly have the accumulation and the loss of MA quality.This control is undertaken by using all use standard industry under meters as indicated above of stdn construction method, level control and flow control circuit.

Continuous stirred tank also can be calibrated according to the required derivation flow of MA solution.Required flow is meant and becomes the mean residence time of reaction mixture in reactor can be enough to guarantee to reach to react completely Vessel Design.Described mean residence time represents that with the V/F ratio wherein V is a reactor volume, and F is the total volumetric flow rate of MAH and water, and it equals the derivation flow of MA under stable state.Preferred 10 minutes to the 1 hour residence time, most preferably 30 minutes the residence time.

During industrial preparation MA, preferably carry out according to 3 footworks that comprise treatment step of the present invention:

The first step is the beginning step, and wherein as described above, the aqueous solution of prefabricated MA is added in the reactor by desired concn, and temperature is raised to target temperature.As long as keep enough MA stockages in the reactor, then this step only need be carried out once in the whole service time limit of described reactor.The required step of unique another is to start after reaching closing condition, wherein may need MA solution is heated to the temperature of reaction that sets.

According to second step of the present invention is to relate to MAH (being preferably molten state) and water are joined preparation process in the MA solution under close control temperature reaction, and the MA that reclaims simultaneously with two kinds of charging equals in quality flows.This recovery of MA can obtain by for example using a kind of pump (for example CSF impeller pump), and flow keeps the control loop of MA constant level in the reactor to control by one.

It is in 20-50 ℃ the jar that the MA that reclaims is stored in storage temperature.Its lower limit depends on the solubility curve of MA: be lower than the crystallization that MA will take place this temperature; And the upper limit provides fumaric acid to form the maximum storage temperature that obtains limiting.For example for the MA aqueous solution of 40% (weight) concentration and the maximum waiting time in 1 week, preferred storage temperature is 40 ℃.

The 3rd step was to stop preparation.This step comprises and stops to add MAH and the temperature reaction in the reactor is cooled to about 40 ℃ from design temperature.After this, the temperature of reactor is arranged on 40 ℃ of the substantially invariable temperature identical with accumulator tanks.

For the present invention can be expressly understood with easy to implement, illustrate preferably that in the mode of embodiment described accompanying drawing is the schema that can prepare the preparation facilities of 10 cubic metres of/hour 40% (weight) MA solution under 65 ℃ temperature of reaction according to method of the present invention and the preparation facilities that is applicable to it now with reference to accompanying drawing.It will be appreciated by those skilled in the art that, because accompanying drawing is a synoptic diagram, so from figure, deleted some conventional equipments for simplicity, such as heat exchanger, pump, valve, vacuum apparatus, temperature sensor, pressure transmitter, pressure controller, condenser, reboiler etc.This optional equipment of those skilled in the art's easy to understand may be shown in production equipment successfully operate necessary, the outfit of these optional equipments and be provided with and do not constitute content of the present invention, they can come for joining according to standard chemical industry convention.

With reference to accompanying drawing, during beginning, the prefabricated MA of 40% (weight) concentration 1. aqueous solution is warmed up to 65 ℃ at a CFSTR with 5 cubic metres of volumes in 2..Then, in case produce, be controlled at 65 ℃ MAH 3. with about 28 ℃ water 4. under agitation with per 3 minutes 1 back and forth pump speed and the mixed traffic of 10 cubic metres/hour water and MAH join CFSTR 2. in.Making the temperature of reaction mixture by the temperature of controlling water inlet is 65 ℃.Simultaneously, from CFSTR 2. reclaim with the MA of two kinds of charging equals in quality 5..Then 5. as the heat exchanger of cooling fluid 6., by water with the MA that reclaims and make temperature reach 40 ℃ and the jar that is stored in storage temperature with 40 ℃ 7. in.

Claims

1. one kind prepares the method for toxilic acid with maleic anhydride and water, and it comprises the following steps:

A). maleic anhydride is contacted the formation reaction mixture with water;

B). reclaim toxilic acid from described reaction mixture; With

2. according to the method for claim 2, wherein said maleic anhydride is a molten state.

3. according to claim 1 or 2 each methods, begin under the existence of the prefabricated toxilic acid aqueous solution of the wherein said 20-60% of being reflected at (weight) concentration.

4. according to the method for claim 3, the temperature of wherein said toxilic acid is at least the melting temperature of maleic anhydride.

5. according to each method of claim 1-4, wherein said temperature reaction is controlled by joining the water of producing reaction.

6. according to each method of claim 1-5, wherein said method is a continuous processing.

7. according to each method of claim 1-6, wherein said being reflected in the continuous flow stirred-tank reactor carried out.

8. according to the method for claim 7, wherein the concentration of toxilic acid is held constant in reactor.

9. according to the method for claim 8, wherein the concentration of toxilic acid is the 20-60% of reaction mixture weight in reactor.

10. according to claim 7 or 8 each methods, wherein said reaction mixture has 10 minutes to 1 hour the residence time in reactor.