CS215003B2 - Method of sulphonation or sulphatation of organic compounds and facility for executing the same - Google Patents

Abstract

The reactor 1 has vertical tubes 10 connected at the top to two common chambers 15 and 17 feeding an organic liquid and an SO3- containing gas respectively. At the bottom the tubes enter a common collecting chamber 40. The gas is fed into the tubes 10 at a pressure of 0.1 to 0.5 bar, which is substantially the same as the head loss over the length of the tubes 10. The liquid is fed into each tube 10 at an overpressure equivalent to 1 to 100 cm of liquid column with respect to the gas feeding pressure. The tubes 10 are externally cooled by water supplied at 20 and withdrawn at 21. <IMAGE>

Description

A method of sulfonating or sulfataing organic compounds on the free surface of a liquid film that is treated with a controlled amount of gaseous sulfonating or sulfating agent. After neutralization, the reaction product is used for the production of surfactants.

The present invention relates to a process for the sulfonation or sulfation of organic compounds, in which a free liquid surface is treated with a controlled amount of a gaseous reagent and an apparatus for carrying out the process. The product of the process is used after neutralization to produce surfactants.

The invention therefore relates to an improved film sulfonation process in a multi-tube reactor as well as a multi-tube reactor for carrying out the process of the invention.

The sulphonation or sulphation of the substances used in the surfactant industry (dodecylbenzene, branched and linear fatty alcohols, ethoxylated fatty alcohols, olefins, fatty acid esters) is currently carried out in various ways.

Among the known methods, methods based mainly on reaction with a gaseous mixture containing sulfur trioxide (e.g., converter gas) are used in a cascade of reactors, where the gas is reacted in stirred vessels with a mass of liquid with gradually increasing concentrations of sulfonated product. the gas reacts continuously with the liquid arranged in the form of a thin layer, at adjusting the flow rate and at such a rate that the concentration of the gas gradually decreases and the concentration of the sulfonated product gradually increases accordingly.

The advantage of the first system is that it is possible to control at different stages of either the desired reaction stage or the reaction temperature, thereby avoiding the formation of an over-sulphonated product due to excessive temperature. Also, the residence time in the reactor, i.e. the contact time of the reactants, can be successfully controlled to complete the reaction by an appropriate dimension of at least one cascade of reactors.

The second system, the so-called film reactor, makes it possible to carry out the reaction in a single reactor with an extremely short contact time of the reactants, with the gas reacting at a gradually decreasing dilution as the degree of reactivity of the components increases.

The sulfonation reaction in the film reactor is currently carried out in various systems.

1.

Film sulphonation in a single pipe reactor. This is the type of reactor initially used for film sulfonation. The single-pipe reactor comprises a single cylindrical vertical tube, at the upper end of which a layer or film of a liquid substance is introduced, which is allowed to flow and adheres to the inner wall of the tube. A gaseous reagent, typically sulfur trioxide diluted with an inert carrier, flows inside the tube.

The coolant is allowed to drain and circulate on the outside of the tube so that the temperature of the mixture remains within predetermined limits during the reaction. A limitation of a single-pipe reactor of this type is that the maximum diameter of the reactor (and thus its maximum operating speed) is tied to the optimum feed rate of the gaseous reactant.

Since most of the reaction at an optimum gas velocity of 20 to 80 m / s takes place in the first very short portion of the reactor, diameters (and thus corresponding production speeds) greater than 2.54 cm lead to an unacceptable reduction of the cooling surface on the outside of the tube. This leads to an increase in the temperature peak in the reaction mass to an unacceptable value and thus poor product quality (poor color due to the formation of over-sulphonated by-products).

2.

Reactor with annular gas space. This type of reactor has two concentric, vertical and coaxial cylinders, inner and outer, which define an annular gas space.

The liquid agent is introduced both on the inner surface of the outer cylinder and on the outer surface of the inner cylinder.

By suitably selecting the ratios - diameters of the two rolls, the cross-sectional area of the reactor can be appropriately adjusted. The cross-sectional area of the reactor is formed by a ring defined by the two cylinders.

However, this type of reactor also has some disadvantages. If it is desired to increase the diameter of the two rollers to increase the production capacity, considerable difficulties arise in forming a constant-thickness liquid film. This requires a very precise reactor design and thus a considerable increase in investment costs. In order to achieve an even distribution of the liquid reagent on the reactor walls without the need for extraordinary precision during the construction and assembly of the unit, an annular rotor of this type is arranged in the upper part of the annular gas space.

However, such a reactor only partially removes the above drawbacks; in fact, at least for the upper portion of the reactor, a higher accuracy is required with respect to the rotating member, whose distance from the two liquid agent films must be carefully determined.

3.

Multi-tube reactors. This type of reactor consists of a bundle of individual tubes, each having an optimum dimension with regard to the distribution of the liquid as well as to the cooling surface and the ease of mechanical construction.

In these reactors, it is most difficult to provide an accurate amount of gas and liquid for each tube to achieve the same molar ratio of reactants predetermined for the reactor in each tube. Numerous authors have recently addressed the problem of resolving this requirement by:

a) using calibrated orifices for the introduction of liquid and gas into each individual tube,

(b) using reaction calibrated tubes, all of which would have the same dimensions: diameter, wall thickness and length;

c) using the pressure of the balancing gas introduced by the distribution nozzles to ensure proper distribution of the reactants in the reactor tubes.

The above arrangements, while improving technological conditions, cannot ensure a perfect molar ratio between liquid and gaseous reagent in individual tubes, but allows acceptable results due to the above-mentioned advantages depending on the use of a multi-tube reactor where each single tube provides optimum operating conditions. if the correct amount of fluids is introduced.

In this way, the best achievable results are the statistical mean value of the more or less optimal values obtained from the individual tubes, although in such a tube, considered individually, the gas / liquid molar ratio may not always be optimal.

The exact gas / liquid ratio is achieved at the expense of considerable heat loss. This also occurs in coaxial tubular reactors, and in particular for the introduction of the gaseous reagent, considerable energy costs and the design problems of sulfur trioxide units are to be expected.

SUMMARY OF THE INVENTION It is therefore an object of the invention to overcome the above drawbacks by combining the individual elements studied and tested for this purpose. They are:

A) Choosing a multi-pipe solution to ensure the best heat exchange conditions and film thickness homogeneity.

B) Selection of optimum size of individual tubes for optimal combination of maximum diameter (lower number of tubes), minimum height (lower pressure losses) but with simple mechanical design.

C) Distribution of the gaseous reagent at negligible pressure losses, adjusting the film thickness in each individual tube and thus the flow rate of the liquid reagent, the reaction profiles and the reaction temperature along the length of the tube.

The combination of these elements makes it possible to achieve excellent results without the need for calibration if the flow rate and / or type of liquid used varies.

Process for sulphonating or sulphating organic compounds with a gas containing sulfur trioxide and a carrier gas by passing the liquid compound to be treated in the form of a film into suitably sized tubes arranged parallel in a vertical direction between the reactant introduction chamber at the top end of the tubes and the reaction product collection chamber at the lower opposite end of the tubes is characterized in that the feed pressure for the gaseous reagent is substantially the same as the pressure drop caused by - the flow of the gaseous reagent within the individual tubes flowing through the reaction liquid; minimum amount.

The introduction pressure of the gaseous agent into each individual tube is 0.01 to 0.05 MPa, preferably 0.02 to 0.04 MPa.

The feed pressure of the liquid reagent with respect to the feed pressure of the gaseous reagent is up to 9.8 x 10 to 9.8 x 10 ³ Pa, preferably 49 x 10 to 147 x 103 Pa.

The inner diameter of each tube is 20 to 40 mm and preferably is 20 to 30 mm, the length of each tube being 2 to 10 m and preferably -5 to 7 m. The outer surface of the tubes is cooled by circulating a suitable coolant.

The carrier gas is formed at least in part by pumped gas from the collection chamber for collecting the product of the same reactor.

An apparatus for carrying out a method according to the invention of the type consisting of a bundle of parallel, vertically arranged tubes, into which a gaseous reagent at the top of a common distribution chamber is introduced, is characterized in that the cross-section of each tube is substantially constant. the cross-section of the gaseous reagent to the lower end.

The liquid reagent is introduced into each tube at its upper end through a round slot provided on the tube. The outer surface of each tube is cooled by a suitable coolant circulating in one or more chambers arranged around the tubes.

The device also has suitable means for adjusting the slot size.

For a better understanding of the invention, an example is now described with reference to the figures, in which Fig. 1 is a schematic vertical section of a reactor suitable for carrying out the invention. Fig. 2 shows an enlarged detail of II in Fig. 1; Fig. III of Fig. 1, Fig. 4 is a schematic cross-sectional view of three reactor tubes showing the operating conditions of the tubes and Figs. 5 and 6 are similar to Fig. 4 showing two other operating conditions.

As can be seen from the figures, the reactor consists of a bundle of vertical, parallel tubes arranged side by side and opening at the top into a feed chamber 70 into which the gaseous agent enters via line 12 from a sulfur dioxide gas producing plant, preferably by catalytic conversion.

The tubes 10 exit down into the collecting chamber 40, in which the reaction products are collected, which are discharged via the line 13, shown only schematically.

In the cylindrical vessel of reactor 1, coolant, preferably water, flows outside the tubes 10. Since the exothermic reaction between the liquid products to be sulphonated or sulphated and the gaseous reagent consisting of sulfur trioxide takes place mainly in the upper part of the tubes 10, it is preferred that the refrigerant flow co-current with the reaction mixture, i.e. downward.

Therefore, at least one refrigerant charge line 20 and a discharge line 21 are provided at the bottom.

Suitable horizontal barriers 22 increase the refrigerant turbulence and increase its path in a known manner. The coolant therefore flows in the space bounded by the outer surface of the tubes 10, the inner surface of the reactor jacket 1 and the two tube sheets 23 and 24 into which the tubes 10 are tightly introduced.

Above the tube sheet 23 is arranged a tube sheet 25, thereby forming a second chamber 15 below the liquid reagent distribution chamber 70. The liquid reagent 15 is fed into the chamber 15 via one or more inlets 16. The liquid reagent enters the individual tubes 10 from the distribution chamber 15 through the filling device shown in detail in FIG.

Each tube 10 extends upwardly into the cylindrical portion 30 of a somewhat larger diameter; the upper part of the tube 10 is connected to the lower part of the extension 30 by a short conical nozzle 31.

The upper widened portion 30 is provided with a plurality of liquid agent apertures 38 and a housing 33 is fitted with a suitable clearance to its outer surface with a suitable clearance which ensures the tightness of the connection to the tubesheets 23 and 25.

The housing 33 is provided with openings 36 for a liquid reagent of a size and circumferential distribution such that it does not cause pressure loss when the liquid passes.

Inside the upper widened portion 30 of the tube 10 is a second sleeve 50, the outer surface of which is flush with the inner surface of the widened portion 30 except for the central region that forms a wide circumferential groove 51.

An annular space is formed by the inner wall of the expanded portion 30 and the peripheral groove 51, which can accommodate the liquid reagent from the openings 38 and 36 opening into the groove 51.

Suitable axial passages 52, shown only schematically in Figure 2, allow the liquid agent to flow out of the annular space defined by the groove 51 downwards. The sleeve 50 is provided at the bottom with a conical tip with the same conicity as the conical sleeve 31 between the enlarged part 30 and the pipe 10.

Between the lower end of the sleeve 50 and the conical sleeve 31 is formed an annular slot oriented along the forming lines of the truncated cone, the width of which is given by the vertical position of the sleeve 50.

At the top, the sleeve 50 is provided with a threaded head 54 that can be screwed into the expanded portion 30. This allows the threaded head 54 to be lowered or raised upward relative to the expanded portion 30 by screwing the threaded head 54, thereby changing the cross-sectional slot. This annular orifice is oriented along the forming lines of the cone and promotes the distribution of the liquid agent into the film designation 60 in FIG. 2 along the inner wall of the tube 10.

Suitably, the inner diameter of the sleeve 50 is identical to the inner diameter of the tube 10 so that the gas coming from the distribution chamber 70 can be brought into contact with the free surface of the film 60 without causing pressure loss. Obviously, due to the design simplicity of the reagent distributor, it is very difficult to achieve accurate flow rate settings. Indeed, deviations greater than 20% between the nominal flow rate and one of the reactor tubes 10 when measured without gaseous reagent delivery were measured.

As will be explained below, variations in the ratio between the flow rate of the gaseous agent and the liquid agent can be kept within narrow limits by the method of the invention. Such a result is quite surprising considering that the main difficulty of all film reactors is precisely the right ratio of the two reagents.

According to the invention, the pressure of the gaseous agent is substantially lower than the pressure of the gaseous agent in the known methods.

According to the invention, this pressure is about 0.01 to 0.04 MPa. Depending on the liquid reagent used, the pressure of the liquid reagent is higher than the pressure of the gaseous reagent and corresponds to the level of the liquid in the liquid distribution chamber.

Despite the low pressure of both reagents and although the flow rate of the liquid reagent may vary up to 20% in individual tubes, it is surprising that the molar ratio of liquid reagent to gaseous reagent remains very close to the given mean value with very small differences in individual tubes, as it results from the results achieved. A possible explanation for this surprising result is elaborated with reference to Figures 4, 5 and 6.

Assuming that in the time interval (t0 to t1 in each of the three tubes 110, 210, 310 of the same diameter and the same length is the same ideal situation, that is, the three flow rates of the liquid reagent 21003 1a, L _b L ₂ , L ₃ are the same, the three flow rates of the gaseous agent G _b G ₂ , G ₃ are also the same, the three molar ratios R _b R ₂ , R ₃ are also the same and correspond to a predetermined optimum molar ratio; then will also react to the same levels of components in pipes, and as shown in FIG. 4 indicate _tí0 P, P ₉₀ and P _98, the step of reacting the components at 60 ° / o, 90 '% I and 98%.

The length of the tubes is chosen such that the contact time of the two reactants is largely sufficient under optimal conditions of introduction of both components to ensure virtually perfect conversion of the liquid reactant (so that the degree of reaction reaches nearly 100 ° / o). In this way, a perfect reaction in each tube is ensured even under conditions differing from optimal conditions if such a condition occurs due to disturbances or similar reasons.

Now, assuming that the flow rates of the gaseous reagent G _b G ₂ , G ₃ remain unchanged in the time interval t ₁ to t ₂ , the flow rates of the liquid reagent L _b L ₂ , L _{3 change} , so that, for example,

Li = L _t / 3, L ₂ = 0.9 L _t / 3, L ₃ = 1.1 L _t / 3, where L _t is the sum of the flow rate of the liquid reagent in three tubes and is kept constant. In the tube 110, the ratios remain clearly unchanged with respect to the conditions shown in Fig. 4, and so the values corresponding to P ₆₀ , P ₉₀ and P ₉₈ also remain unchanged. Consequently, the lower flow rate of liquid in the tube 210 will increase the values of P _tí0, P ₉₀ and P _98, while the contrary happens к opposite results in the tube 310, due to the greater flow rate of liquid reagent.

It is recalled that the pressure differences in the distribution chamber 70 and in the collection chamber 40 correspond to the pressure loss in each of these three tubes, in which the pressure loss is therefore the same.

It is further recalled that, along with variations in the degree to which the reaction took place, the viscosity and thus the thickness of the film formed by the mixture of the liquid reagent and the liquid reaction product vary considerably. Especially with the increasing degree to which the reaction has taken place, the viscosity and the thickness of the film consisting of a mixture of the liquid reagent and the liquid reaction product increase.

Giant. 5 shows that the height H _{3 of the} portion of the tube 310 where the degree of reaction is greater than 98 is shorter than the corresponding height of 1¾ of the tube

110, the height H _b being shorter than the height H ₂ .

Due to its different lengths H _b H2,

H ₃ , therefore, the three tubes have a different mean cross section of the gaseous reagent passage since the mean thickness of the liquid film on the tube walls is different. Since the three flow rates of the gaseous reactant in tubes 110, 210 and 310 clearly depend only on the corresponding mean cross-section, and the pressure difference at the extreme differences in the three tubes is the same as above, the following results are obtained:

in a tube 210 with a middle passage smaller than that initially shown in FIG. 4, the flow rate of the gaseous reagent decreases, thereby reducing the molar ratio below the optimum initial initial value; in the medium passage tube 310 larger than initially shown in FIG. 4, the flow rate of the gaseous reagent increases, thereby shifting the molar ratio above the optimum initial initial value.

When beginning from the time t _b, it is possible that although remains constant and the same flow rate L _B Lo L ₃ of the liquid reagent, changing the flow rate of the gaseous reactant so that, as shown in FIG. 6 is = G _t / 3,

G ₂ = - 0,9 _Gt / 3,

G ₃ - 1.1 G _t / 3, where G _t is the sum of the flow rate of the gaseous reagent in all three tubes, kept constant.

In the tube 110, the situation remains clearly unchanged with respect to the situation of FIG. 4 and therefore the location of the values P ₆₀ , P ₉₀ and P ₉₈ does not change. Due to the lower flow rate of the gaseous reagent in the tube 210, the P _69, P ₉₀ and P ₉₈ values decrease, while the higher flow rates of the gaseous reagent in the tube 310 increase these values.

For the same reasons as above, there к low flow of the gaseous reagent in the tube 310 and to increase the flow of the same gaseous reagent in the tube 210, as the corresponding mid-section in the pipe 310 falls and rises in the tube 210. In this case, the molar ratios of R ₂ and R ₃ will move in the direction of the main к optimum.

In addition to the above-mentioned equalization phenomenon, based on modification of the reaction profiles of the tubes, there is another important equalization phenomenon which utilizes considerable changes in viscosity with temperature. If the temperature of the liquid film inside the tubes changes, the mean liquid viscosity also changes accordingly. As a result, for the same flow rate as the average film temperature increases, the average film thickness decreases, and thus the mean cross-section for the passage of the gaseous reagent increases. Opposite ratios occur when the mean film temperature drops.

Therefore, considering the three tubes of Figure 4 and the possible different situations of Figure 5, for the tube 210, characterized by a decrease in the flow rate of the liquid reagent, the overall result of the reaction will be less reagents per unit of time and thus less reaction heat. Since the temperature and flow conditions of the cooling medium remain the same, at this point the mean film temperature decreases with respect to the original value due to the lower reaction heat to dissipate the cooling medium. This will result in a higher mean viscosity, a higher film thickness, and a reduction in the cross-section for the passage of the reaction gas.

Since the pressure in the tube 210 does not change, the flow rate G _{2 of the} reaction gas decreases, and therefore the molar ratio R ₂ decreases and returns to its original optimum value. On the other hand, in the case of the tube 310 under the conditions of FIG. 5, increasing the flow rate of the reaction liquid will lead to an increase in the amount of reactants per unit of time, thereby increasing the release of the reaction heat. Thus, these are completely opposite to the foregoing conditions and their ultimate result is an increase in the mean film temperature, a decrease in the mean viscosity of the film and thus a larger cross section for the passage of the reaction gas. In this case, the rate of arrival of the reaction gas increases so that the molar ratio R ₃ value increases in the direction of its original optimum value.

Under the conditions of Fig. 6, where the liquid flow rate remains constant, the mean film temperature is practically unaffected, - sulphonable matter content in the feedstock - average molecular weight of the feedstock - feedstock flow rate - volume concentration of sulfur trioxide in the carrier gas reactor - the inlet pressure of the gaseous reagent introduced into the reactor - the overpressure of the liquid reagent and therefore a balancing effect based only on the variation of the reaction profile is applied.

These two balancing phenomena are so pronounced that they compensate for the imbalance caused by the variation in the flow rate of the reactants and, as is clear from the above, do not restore the original optimum flow rate values in each tube but only the original molar ratio between the two reactants. .

In fact, based on the ideal situation of Figure 4, after the transition period, the effect of equalization phenomena is applied and a unique overall material equilibrium occurs throughout the reactor:

Rj = R ₂ = R ₃ = R _t = - g Therefore, despite the fact that the flow rates in each pipe differ from the ideal flow rate

The GT / 3 and LT / 3 molar ratio in each tube is correct and is adjusted by the external reactor control means.

The following examples illustrate the process of the invention.

Ex 1 adl

This example shows the advantages of the sulfonation process of the invention for the case of technical linear dodecylbenzene with a wide spectrum of composition and aliphatic chain length of 9 to 15 carbon atoms.

98.5%

267

180 kg-h%

to 40 ° C

18.6 kPa cm @ ^{-1 of} liquid reagent column

The reactor according to the invention has the following characteristics:

- number of pipes - inside diameter of pipes - length of pipes mm 6000 mm

The analytical composition and characteristics of the fiber having a temperature of 25 ° C are used as coolants. The temperature of the sulfone product obtained after aging and after the stabilization of the fuel at the outlet of the reactor was 45 ° C.

213003 - amount of non-sulfonated fractions in reaction product - amount of free sulfuric acid - color of product

1.35% below 1% 25 ° Klett

Example 2

This example shows the advantages of sulphation - mean molecular weight of feedstock - feedstock flow rate - sulfuric acid bulk concentration in carrier gas - temperature of sulfur trioxide introduced into reactor - liquid reagent overpressure of liquid reagent column - inlet pressure of gaseous reagent introduced into reactor according to the invention for the case of synthetic lauryl alcohol (12 to 15 carbon atoms).

207

150 kg / h%

° C cm **

19,1 kPa

The reactor used has the same characteristics as the reactor used in Example 1.

As the cooling medium, the amount of non-sulfonated fractions in the reaction product, the sodium sulfate content, the color temperature of 20 ° C is used. The sulphated product discharged from the reactor has a temperature of 39 ° C.

Analytical composition of the neutralized product:

1.9 O / o

0.88% ° Klett

The neutralization is carried out in aqueous solution. The above values for the content of unsulfonated material and sodium sulphate refer to 100% of the active ingredient.

Example 3

This example illustrates the advantages of the sulfation of the invention for the case of synthetic lauryl alcohol (C 12 -C 15) ethoxylated with three molecules of ethylene oxide.

- average molecular weight - flow rate of feedstock - volume concentration of sulfur trioxide in carrier gas - temperature of sulfur trioxide introduced into reactor - inlet pressure of gaseous reagent introduced into reactor - overpressure of liquid reagent

339

130 kg / h

2.5%

30.6 kPa cm * · ^x) liquid reagent column

The reactor used has the same characteristics as the reactor used in Example 1.

The product at the inlet of the reactor had a temperature of - the amount of unsulfonated product - a content of sodium sulfate - a color of lot 40 ° C. The cooling water has a temperature of 30 ° C. Analytical composition of the neutralized product:

1.3%

1.4%:

° Klett

Neutralization is carried out immediately after sulfation in aqueous solution. The above values of the content of unsulfonated product and sodium sulphate refer to 100 why active ingredient.

It is recalled that in all three examples, the molar ratio of the reactants (sulfur trioxide and liquid reagent) was maintained at (1.03 to 1.06): 1.

The color of the final product was determined in each case by a Klett-Summerson blue filter with a 5% solution. 40 mm cells are used.

The color of the product taken directly from the reactor without any bleaching process is always determined.

Of course, the process of the invention is not limited to the three examples, but naturally applies to all modifications that are covered by the definition of the subject matter of the invention.

Claims (5)

OBJECT OF THE INVENTION A process for sulfonating or sulfating organic compounds with a gas containing sulfur trioxide and a carrier gas by passing the liquid compound to be treated in the form of a film into suitably sized tubes arranged parallel in a vertical direction between a distribution chamber for introducing reactants at the upper end of the tubes and a collection chamber for collecting the reaction products at the lower, opposite end of the tubes, characterized in that the gaseous reagent is introduced at a pressure corresponding to the pressure drop caused by the flow of gaseous reagent within the individual tubes flowing through the reaction liquid; and wherein the feed pressure of the gaseous reagent into each tube is 0.01 to 0.05 MPa, preferably 0.02 to 0.04 MPa, and the feed pressure of the liquid reagent with respect to the feed pressure of the gaseous reagent. Reagents 1 to 100 cm, preferably 5-15 cm column of liquid. 2. The process of claim 1 wherein the carrier gas is at least partially formed by the waste gas from the reactor header. Device for carrying out the method according to Claims 1 to 2, characterized in that it consists of a bundle of parallel, vertically arranged tubes (10), at the upper end of which there is a filling chamber (70) for gaseous reagents below which there is a chamber (15). for distributing a liquid reagent connected to the inner upper widened portion (30) into which the tube (10) opens, the distribution chamber (15) being connected to the inner space of the tubes (10) by a circular adjustable slot disposed at the upper end of each tubes (10), the tubes (10) being surrounded by cooling chambers. Device according to claim 3, characterized in that the inner diameter of each tube (10) is 20 to 40 mm, preferably 20 to 30 mm. Device according to claim 3, characterized in that the length of each pipe is 2 to 10 m, preferably 5 to 7 m.