DE1000363B - Process for the production of glycerin - Google Patents

Description

The invention relates to the conversion of i-halo-2,3-epoxypropanes into glycerol.

A number of different methods for the synthesis of glycerin have been proposed. The most successful of these processes is based on hydrolysis of mono- and dichlorohydrins. Aqueous metal hydroxide solutions or salts of a strong base with a weak acid such as sodium carbonate was used as a hydrolyzing agent. All older procedures have disadvantages when carried out on a technical scale. The formation of by-products, in particular of higher molecular weight products, such as polyglycerols, is one of the disadvantages, since it results in the yield is reduced in glycerine and the recovery of the glycerine in pure form is more difficult. Increased consumption of chemicals and a relatively slow reaction make the use of large and expensive reaction vessels are necessary. It is also necessary to use less aqueous solutions Concentration to work so that large amounts of water must be evaporated to make glycerin usable To gain shape.

According to the invention, these disadvantages are avoided if the hydrolysis of the i-halogen-2,3-epoxypropane is used by brief contact at high temperature and high pressure with an aqueous inorganic Carries out carbonate solution. The reaction will take place for about 5 to 20 minutes at a temperature from 130 to 200 °, preferably from 150 to 180 °, in The presence of carbon dioxide carried out under sufficient pressure to keep the reactants in the to keep liquid phase. The optimal temperature and residence time will vary somewhat with the glycerol concentration of the fully hydrolyzed product, as can be seen from the following numerical values.

Glycerol concentration
in percent by weight. 5 10-15 20-25

Temperature in ⁰ C .... 154-166 157-180 163-180 Dwell time in minutes 9-15 7-9 8-10

Temperatures and residence times above these optimal ranges favor the formation of polymers, below the optimal ranges they lead to incomplete hydrolysis. Temperature and dwell time are mutually dependent values. The specified optimal ranges define the limits within an adjustment of one variant over the other gives the best yields. Will be common the residence time is determined by the volume of the reaction vessel and the optimum yield is determined by Adjustment of the reaction temperature obtained.

By this procedure, a complete conversion of the i-halogen-2, 3-epoxypropane can be achieved at very high low by-product formation can be achieved. The process of making glycerin

Applicant: NV De Bataafsche Petroleum
Maatschappij, The Hague

Representative: Dr.-Ing. F. Wuesthoff, Dipl.-Ing. G. Pulse

and Dr. E. von Pechmann, patent attorneys,

Munich 9, Schweigerstr. 2

Claimed, priority:
V. St. v. America April 19, 1954

Kenneth Burl Cofer, Emeryville, Calif. (V. St. A.),
has been named as the inventor

The reaction can advantageously be carried out with halogenepoxypropane solutions in a relatively high concentration Aqueous solutions with about 15 to 30 percent by weight of i-chloro-2, 3-epoxypropane are used. In contrast to older processes, the formation of high-boiling substances is at these high concentrations very little, and the amount of water that must be evaporated in the recovery of the glycerine is essential less.

In addition to the improved glycerol yields, a major advantage of the new process compared to previous practice is the major improvement in the utilization of alkali. Preferably the process with an excess of 15 to 2O is performed ° / ₀ inorganic carbonate. Smaller of carbonate give a less complete hydrolysis, especially if less / ₀ surplus reach as io ° to the application.

Larger amounts of inorganic carbonate do not improve the yield of glycerol, but only increase it Stress in removing the salt.

The utilization of the inorganic carbonate is further increased if one uses higher concentrations works on i-halogen-2, 3-epoxypropane. It has been found that if you get the optimum from 15 to 20% Sodium carbonate excess in the product maintains the consumption of sodium carbonate of 79 kg fell to 71 kg per 100 kg of glycerine produced when the Glycerol concentration was increased from 15 to 25 percent by weight, the other conditions being the same was. This unexpected improvement is believed to be likely due to decreased solubility the non-glycerol precursors in the reaction

3 4

Medium at higher concentrations to be attributed to a mixture of the glycerine with the incompletely hydro-

consequent reduced reactivity of this lysed reaction mixture. You can also use a com

Impurities with the carbonate. Bination of reaction tubes with a tank container

Carbonates, such as sodium carbonate, can be used in the initial stages of the reaction

present method can not be selected by other bases 5 that z. B. about in the first fifth

replace without sacrificing important advantages of the invention. up to about third of the total reaction volume of the

The carbonation is an important factor that takes place for the greater part of the hydrolysis and in heated

reduced by-product formation is performed for both reaction tubes. The drawing is

the rapid catalysis of hydrolysis and hydration a schematic diagram of such a suitable

reaction is responsible. Carbon dioxide from the reaction system in which the units are not

Reaction mixture can also act as a catalyst are just drawn.

as well as a buffer to a too high _pH value to comparable ι In the drawing, a reservoir means

prevent excessive polymerization for the starting material which passes through line 2

is prevented. Of course, this does not include the presence - withdrawn and added together with line 3

means small amounts of other basic agents, provided that 15 conducted sodium carbonate solution is fed to the pump 4

they do not change the reaction significantly, which is only when they reach the preheater 5. In this pre

z. B. more than about 10 to 15 weight percent sodium heater is the feed mixture by indirect

hydroxyd is the case. The carbonate can advantageously be supplied with heat from water vapor introduced at 6

heated by absorption of the released in the reaction, the condensate drawn off through line 7

Carbon dioxide can be generated in caustic soda solution. 20 turns. The so heated and withdrawn through line 8

The preferred inorganic carbonates for the reaction mixture can be further introduced by direct introduction

Use in the method according to the invention are to be heated by high pressure steam through line 9.

Alkali carbonates and bicarbonates. Sodium carbonate and the mixture thus heated, which under a pressure

-bicarbonate are available because of their low price and their standing from 7 to 35 at, is in the reaction vessel 10

good solubility in the reaction medium is particularly valuable, which has a sufficient number of tubes

fully. Alkaline earth carbonates can also be used to make up a quarter of the total required

However, because of their low solubility, less reaction vessel volume has to be delivered, and then arrives

desirable. through line 12 while maintaining the reaction

The process has been found to be particularly valuable in temperature and reaction pressure to the tank for the hydrolysis of i-chloro-2,3-epoxypropane 30 container 13 in which the hydrolysis is completed. One to glycerin. However, it has also been used with success for the total residence time of about 5 to 15 minutes in the hydrolysis of i-bromo-2,3-epoxypropane. Reaction vessels 10 and 13, which are advantageously insulated. Other i-halo-2,3-epoxypropanes can be used in more similar ways, in order to preserve heat, and in additional ways. The starting material can be provided with heating means, is expedient. The i-halogen-2,3-epoxypropane can be produced in the reaction mixture 35, reaction mixture, through line 14, which contains a pressure reducing valve 15 from the corresponding dihaloxypropane, to a flash evaporator. In such cases, it is only necessary to remove drum 16, in which carbon dioxide is separated from the amount of sodium carbonate used by aqueous glycerol solution and withdrawn through line ¹ _{and 2} mol for each additional equivalent of device 17 present. This solution is increased by halogen. Mixtures of dichlorohydrins and 40 line 18 discharged. The excess of sodium carbonate-epichlorohydrin, e.g. B. in the US patent nat in the glycerol solution is introduced with acid, those described by 2,605,293, are suitable starting materials line 19 in the neutralization tank 20 for the new process. There can be various working is, neutralized, from which the solution is removed through line 21 used for carrying out the process and to the evaporator and distillation. It can be run intermittently, with interruptions or 45 systems 22 and 23. The resulting salt can be worked continuously. is removed and withdrawn through line 24 while

The preferred continuous process is water and low boiling impurities

one can use a reaction vessel, the line 25 and the high-boiling impurities

optionally filled with suitable inert packing elements through line 26 withdraws. The glycerin produced is

is, or it can be a container without packing. The 50 won from line 27.

The reaction container can be a horizontal or a vertical boiler, in which case the halogen is drawn off carbon dioxide along with epoxypropane or its precursors and the carbonate solution to be converted from the neutralization container 20 through line 28 through the drum Carbon dioxide discharged from the reaction into the absorber 29 either in an upward or downward 55 leads. In the absorber, the gaseous coal-directed stream is fed. A reaction vessel without dioxide in countercurrent to the packing material fed in through line 30, made of passages or tubular sodium hydroxide solution. The resulting sodium carbonate coil offers advantages, in particular because it allows a solution to be withdrawn through line 31 and due to good temperature control in the reaction. Line 3 together with sodium carbonate solution for such reaction tubes can be gradually replenished through line 32 to increase the temperature as the reaction proceeds to reaction vessels. By doing this, the advances are advantageously halted. An amount of the base required to zuwirksamere through line 30 use of inorganic carbonate guided sodium hydroxide and through conduit 32 is obtained in such reaction vessels, apparently supplied sodium carbonate at 20 to 35 ° / ₀ low, due to reduced back mixing and resulting 65 than when the hydrolysis with Buffered sodium suppression of side reactions between the hydroxyd according to the best known Ver sodium carbonate and the impurities in the drive is carried out. The amount of acid produced by charging. A formation of undesirable, high-line 19 must be fed, and the amount of salt, boiling by-products is also prevented in tubular reaction vessels, which must be removed from the glycerol, by reduced return 70 correspondingly. The formation of

unwanted high-boiling products is only a tenth to a quarter of the amount previously produced.

The following examples explain the process in the hydrolysis of i-chloro-2, 3-epoxypropane:

Example I.

i-chloro-2,3-epoxypropane (produced by steam distillation of chlorohydrin produced from allyl chloride), which according to the analysis contained about 75 percent by weight of i-chloro-2,3-epoxypropane, was used as the starting material for a reaction tube made of 30 m steel tube of 15 cm Diameter, which was arranged in a vertical shaft of four horizontal passages connected in series, supplied. The i-chloro-2,3-epoxypropane and aqueous sodium carbonate feed streams were mixed in a feed pump distributor and fed to the reaction vessel at a pressure of about 10.5 atm. The heat for the reaction was applied by introducing direct steam at a pressure of about 12.25 ^a * ^at a point about 1.2 m downstream from the feed inlet. The product coming out of the reaction vessel was let down to atmospheric pressure and the aqueous glycerol was separated from the carbon dioxide. The carbon dioxide was absorbed in caustic soda to form sodium carbonate for further hydrolysis. The aqueous glycerin solution was neutralized, evaporated and distilled to obtain anhydrous purified glycerin.

The following results were obtained in tests with various concentrations of i-chloro-2,3-epoxypropane, expressed as the concentration of glycerol equivalents in the reaction mixture.

Equivalent glycerol concentrations
I * 5 per cent

25 7 »

Temperature in ⁰ C

Dwell time in minutes

excess sodium carbonate in the product in

Weight percent

Glycerin in the product in percent by weight

Alkali consumption, 1 part by weight sodium carbonate feed per 100 parts by weight of glycerine produced ...

Ratio of table salt to glycerine in the product ...

Ratio of water to glycerine in the product

Yield, based on the glycerine precursors added, in%:

Glycerin

Polymer

not hydrolyzed

The temperatures given are the maximum temperatures reached during the reaction. A certain Reaction takes place even at lower temperatures, at which the reactants mixed and can be pumped to the reaction vessel.

The residence times given in the previous table are calculated by dividing the volume of the reaction vessel divided by the feed rate in volume units per minute. The actual Residence time of the liquid in the reaction vessel is somewhat shorter because of the volume part of the carbon dioxide released during the reaction.

Example II

Batch hydrolysis was attempted in a high pressure stainless steel reaction vessel 154-156
8 to 15

15 to 20
4 to 6

81 to 84
1.10
18.0

38.5
i, 3
0.2

157 to 180
7 to 9

15 to 20
13 to 18

76 to 79
0.71
5.0

1.0
o, 5

163 to 180
8 to 10

15 to 20
20 to 25

64 to 72
0.67
2.5

97, i
2.6

o, 3

carried out, which was equipped with a high-speed mixer and a built-in heating coil. The reaction vessel was charged with heated aqueous sodium carbonate solution, then the i-chloro-2,3-epoxypropane (corresponding to 78.9% glycerol) was added and the reaction vessel was sealed. The mixture had a temperature of 80 to 90 ⁰ and was then heated to the reaction temperature. When the evolved carbon dioxide had increased the pressure in the reaction vessel to the desired level, the pressure was kept constant for the remainder of the reaction time by releasing gas through a pressure relief valve.

The following shows the results under various reaction conditions.

Together
i-chlorine establishment of the B
"^ Yes ^ T * i 11 τη * · dispatch Stoichio
metric
Excess
of Na, CO ₃ Highest
React
functional
tem- Highest
Reak
functional
pressure Reak
ions
time ¹ ) not
hydrolyzed
Glycerin
preliminary products High
boiling
Products Glycerin
yield 2,3-epoxy Xi et Li. I LLIi-X
C 3.Γ t) O Tl PL "t" water temperature Weight Weight Weight propane V. ⁰ C at Minutes percent percent percent 10.1 6.4 83.7 5 162 470 15th 1.8 i, 3 97.8 15.0 8.6 76.0 2 160 450 15th 3.6 0.4 97.2 20.0 ii, 5 68.5 no 165 400 15th o, 4 2.8 97.4 20.1 ii, 7 68.2 2 165 420 15th no 2.2 97.3 25.0 14.3 60.7 no ISS 360 15th i, 7 0.5 98.0 24.7 14.9 60.4 5 163 450 15th no 0.3 98.8 24.6 15.4 60.0 IO 161 445 15th 1.0 1.1 98.6 24.5 14.9 60.6 5 ! S3 200 15th no - 99-0 24.6 15.5 59.9 IO 152 410 16 no - 99.2

The reaction time is the total residence time in the reaction vessel including the heating time.

Glycerin Yield losses ¹ ), Poly
merisat concentrate related to feed on Weight tration Glycerine precursors percent Maximum 1.7 temperature Weight not 1.9 percent hydrolyzed
material 5.6 Weight 2.3 ⁰ C 5.0 percent 135 5.5 3.3 149 5.4 1.3 163 0 173 0.2

Glycerine yield
+ Polymers).

100 - (non-hydrolyzed material

Reaction tube

Response time 6.9 to 9.3 minutes

Excess
15 to 32 percent by weight of sodium carbonate

Example III

The influence of changing the highest operating temperature on the results of hydrolysis of Mixtures of i-chloro-2, 3-epoxypropane (75 to 80%) with about 20 to 25% glycerol dichlorohydrin were used in two test series determined under different conditions. A series of tests was carried out in the tubular Reaction vessel carried out according to Example I, and the other experiments were carried out in a reaction tube with a diameter of 60 cm and a height of 465 cm. The charge of i-chloro-2,3-epoxypropane (78 to 84Ύ0 glycerol precursor) with sodium carbonate mixed by a single-stage suction centrifugal pump and placed in the bottom of the reaction vessel under pressure of approximately 10.5 at. The reaction vessel water vapor of about 12.5 atm was supplied and the product was drawn off from the upper end of the reaction vessel and placed in a phase separator passed in which the aqueous glycerol was separated from the carbon dioxide.

Vertical reaction tank

Response time 12 to 16 minutes

Excess a ₅

16 to 23 percent by weight of sodium carbonate

i-chloro-2, 3-oxypropane, as used in Example III, is used in the following table on experiments shown that at temperatures from 157 to 177 ° with the in Example I described reaction tube and the vertical reaction vessel used in Example III were carried out.

Glycerin Sodium-
carbonate Loss of yield, Poly
merisat focus
tration excess based on Weight in the Glycerin percent Dwell time
in the product Weight preliminary products Reaction vessel Weight percent not O percent ayaxo-
lysed
material 9.7 Weight 1.5 Minutes 5.2 percent I, O Reaction tube: i6.8 2.5 6.7 3.6 39, o 2.9 Reaction tank: 4.2 7.5 * .9 IO 5.8 0 1.6 15th 13.7 O 2.7 25th 15.5 14.8 O 3.O Reaction tube: 15.7 II.4 5.4 16.6 134 0.6 3.2 7, i 17.8 0.6 2.8 10.4 9-4 0.8 3.6 13.0 21.5 29.4 0.4 3.4 Reaction tube: 20.2 13.3 6.5 26.6 21.4 0.8 7.2 24.8 0.2 ii, 5 0.3 12.3 0.1

35

Example V

The effect of the excess amount of sodium hydroxide in carrying out the hydrolysis of the impure i-chloro-2,3-epoxypropane according to Example III is illustrated by the following results, which in the reaction vessels described in Examples I and III.

45 Vertical reaction tank

Glycerin
focus Loss of yield '). Feed on Τ) _Λ | tration based on Glycerine precursors FoIy-
merisat Maximum not Weight temperature Weight hydrolyzed
material percent percent Weight o, 9 12.8 percent i, 5 ⁰ C 13.2 0.5 1.6 151 15.7 0.5 2.8 164 23.6 0.3 3.9 177 22.4 0.2 179 0.3 186

Maximum temperature 157 to 166 degrees

Glycerine concentration in the drain ... 4 to 6%
Residence time 10 to 16 minutes

Loss of yield, based on Polymers Sodium- Glycerine precursors Weight percent excess
55 not hydrolyzed
material 2.7 Weight percent Weight percent i, 9 3.7 0.1 i, 5 60 6.2 0 i, 5 16.8 0 i, 5 19.8 O 1.6 20.3 0 44.6 0

Glycerine yield
+ Polymers).

= 100 - (unhydrolyzed material

Example IV

The effect of changes in residence time on the yield losses in the hydrolysis of impure Reaction tube

Maximum temperature 162 to 182 °

Glycerine concentration in the drain ... 20 to 27%

Residence time 7 to 11.5 minutes

Loss of yield, based on Polymers Sodium- Glycerin products Weight percent excess Not hydrolyzed
Materia) 5.0 Weight percent Weight percent 4.1 5.5 0.9 4, i 7.4 1.3 3.4 9- ¹ 0.4 2.8 II.3 0.6 2.6 13.3 o, 3 2.8 23.0 0.4 2.8 25.2 0.2 2.8 26.5 0.2 29.4 0.2

Claims (5)

PATENT CLAIMS: i. Process for the production of glycerol by hydrolysis of i-halogen-2, 3-epoxypropanes, characterized in that the hydrolysis within 5 to 20 minutes with an aqueous solution of an inorganic carbonate at a temperature of 130 to 200 ° is carried out in the presence of carbon dioxide under such a high pressure that the Reactants remain in the liquid phase. 2. The method according to claim 1, characterized in that the aqueous inorganic _{carbonate solution is used in an excess of 2 to 20 ° / 0 of} the amount required for hydrolysis and the carbonate solution is sodium carbonate or bicarbonate solution. 3. The method according to claim 1 and 2, characterized in that the components of the reaction mixture are coordinated so that they result in a glycerol solution with a concentration of about 15 to 25 ° / ₀ . 4. The method according to claim 1 to 3, characterized in that the reaction at a Performs temperature between 150 and 180 °. 5. The method according to claim 1 to 4, characterized in that i-chloro-2,3-epoxypropane used as i-halogen-2,3-epoxypropane. 1 sheet of drawings © 609 740/418 12.56