GB2181145A - Process and apparatus for producing isobutylene polymers - Google Patents

Abstract

The present invention relates to the chemistry of polymers and, more particularly, to a process and an apparatus for producing isobutylene polymers. The process comprises supplying a stream of an isobutylene-containing feedstock into the reaction zone of a reactor at an angle of 30 to 120 DEG to the axis of a flow of the reaction mass simultaneously with admission of a stream of a solution of an acid catalyst in at least two points; the catalyst stream direction constituting an angle of from 30 to 90 DEG to the direction of the feedstock stream. The next step of the process comprises polymerization of the feedstock in the reaction mass flow turbulently moving along the reactor at a speed of from 0.3 to 15 m/s. The apparatus for implementation of this process comprises a reactor-tube (1) with an inlet socket pipe for the catalyst supply (2) positioned on the end face of the tube (1) and directed inwardly and provided with at least two openings (6) on its cylindrical surface with their axes forming an angle of from 30 to 90 DEG to the axis of the tube (1). The reactor-tube (1) also has an inlet socket pipe for the feedstock supply (7) positioned on the cylindrical surface of the tube (1) close to the end face thereof.

Description

SPECIFICATION Process and apparatus for producing isobutylene polymers The present invention relates to the chemistry of polymers and, more specifically, to a process and an apparatus for producing isobutylene polymers.

Isobutylene polymers found an extensive application in the chemical and petrochemical industries as lubricating and cooling liquids, electroinsulating oils, additives to fuels and oils, components of sealing, adhesive and insulation compositions.

At the present time the main process for producing isobutylene polymers is based on a cationic polymerization of an isobutylene-containing feedstock in the presence of acid catalysts.

As the starting feedstock use is made of commercial fractions of C4-hydrocarbons with a content of isobutylene of from 20 to 60% by mass and solutions of individual isobutylene in organic solvents (content of isobutylene of from 10 to 40%). As the solvent, halogen-containing hydrocarbons (CH3CI, C2H5CI and the like) are mainly used.

The polymerization catalysts are individual Lewis acids and complexes based thereon (AICI3, BF3, C2H5AICI2, SnCI4) employed as solutions in organic solvents (C2H5CI, isobutane, toluene).

The process of isobutylene polymerization is conducted at a temperature of from - 100 to +50"C under intensive stirring.

The reaction of polymerization proceeds at a high speed; it is exothermal and accompanied by release of a great amount of heat (about 72 kJ/mol).

This intensive heat release during polymerization imposes severe requirements on the reaction thermostatting which is accomplished by a number of methods: the use of diluted solutions of the monomer, a portion-wise introduction of the catalyst solution, boiling of a portion of the monomer or specially introduced volatile solvents and an intensive heat removal at the account of a well-developed outer and inner thermostatting surface area of the reactor employed.

The process of polymerization of the isobutylene-containing feedstock is carried out in continuous-action polymerization reactors of a high volume (2 to 30 m3) provided with internal and external thermostatting means of various design. As the thermostatting agents liquid ammonia, ethylene and various antifreezing agents are used. The reactors comprise tubular or column-type apparatus provided with powerful agitation means to ensure high coefficients of the heat- and mass transfer. To control the temperature conditions of the process of isobutylene polymerization, mixing reactors are used which have a free space to ensure boiling and evaporation of a portion of the monomer or solvent. The process control is also achieved by carrying out the reaction in a series of mixing apparatus, wherein a certain degree of the monomer conversion is reached in each individual apparatus.For this reason, the heat release per one apparatus is lowered. In all cases a high conversion of the starting feedstock is attained at an average residence thereof in the reactor of more than one hour.

These prior art processes for producing isobutylene polymers have the following disadvantages. First of all, it is a high metal-consumption for the process associated with the use of heavy-duty apparatus of a sophisticated design. This also implies the need in skilled personnel for servicing and maintenance of the process equipment. Secondly, the presence of systems providing intensive heat- and mass-transfer in the reaction brings about high rates of power consumption. They are increased non-linearily upon increasing a unit capacity of an apparatus or in the case of a series of apparatus, i.e. in the schemes intended for a better thermostatting of the process and a higher quality of the final product.Thirdly, despite the number of techniques aimed at maintaining a constant temperature of the reaction, the process occurs under nonisothermal conditions with a temperature gradient over the volume of the reaction mass. This results in non-uniformity of isobutylene polymers in respect of molecular masses thereof, in particular in the origination of low-molecular fractions impairing exploitation properties of the products. Fourthly, a long residence of the starting feedstock in the reactor (measured in hours) unreasonably incomparable with the proper polymerization time (seconds) results in a limited productivity of the reactor and an impaired quality of the product due to the occurrence of side processes.

The improvement of processes for producing isobutylene polymers envisages reduction of metal- and power-intensity of the process, higher reliability of thermostatting simultaneously with ensuring a high output and quality of the polymeric product.

From this standpoint the production of isobutylene polymers in small-size tubular reactors is the most promising route. Thus, French Patent No. 1,396,193 teaches polymerization of isobutylene in a C4-fraction in a steel pipe of the volume of 0.5 1 (diameter 20-30 mm, length 700 mm). The polymerization of the starting feedstock preliminarily cooled to a temperature of from -80 to - 1000C amd mixed in a special mixer (0.005 1 capacity, impeller rotation speed 1,500 r.p.m.) with the catalyst C2H5AICI2 is effected in a laminary stream (without agitation) under adiabatic conditions (at a temperature of from 0 to -- 130"C). The linear rate of the reaction mass flow is 1 to 2 cm/s.This method has the following advantages: simplicity of the polymerization reactor design, high degrees of conversion of isobutylene (close to 100%) and the possibility of producing polyisobutylenes of a different molecular mass (from 2,000 to several million).

But, despite these advantages, this prior art method has serious drawbacks. The adiabatic conditions do not ensure isothermal character of the process (the temperature drop at the inlet and outlet of the reactor is within the range of from 40 to 100"C) which results in the production of a polymer having high non-uniformity of molecular masses, i.e. of a poor quality.

The use, in the process scheme, of a small-size and a low-productivity mixer of the feedstock with the catalyst, though featuring a high economic efficiency, imposes limitations on the output of the product from the tubular reactor constituting 1-4 kg of the polymer an hour on the average.

The productivity of the employed reactor is also rather low due to restrictions of the feedstock composition: the use of a fraction with a high (above 50%) content of isobutylene is impossible due to a noticeable disbalance in the heat release and heat consumption which interferes with the required laminary conditions of the process.

The necessity of using a powerful source of cold (liquid ethylene) for a preliminary cooling of the components imposes strict requirements on the process equipment which renders the process rather complicated and both fire- and explosion hazardous.

Better parameters of the process are attained in the case of polymerization of isobutylene in a tubular reactor disclosed in FRG Patent No. 2,904,314.

The polymerization of isobutylene in the composition of the C4-fraction is effected in a stream of the feedstock turbulently moving at a linear rate of from 0.5 to 20 m/s at a temperature of from -50 to +80"C under a pressure of up to 50 atm.

As the process catalyst BF3 is used in an amount of from 1 to 20 mmol per mol of isobutylene. The use of cocatalysts (water, alcohols) is also permissible in an amount of from 0.2 to 1 mol.% relative to BF3.

An average reaction time is 1-40 s, the conversion is near 100%. The reaction yields polymers with a molecular mass of from 500 to 5,000 suitable for the production of additives.

The process is effected continuously in a tubular reactor with a length of 5x 102 to 8x 106 mm and a diameter of 10 to 100 mm preferably having a helical or coiled shape and placed into a thermostatting medium (liquid ammonia).

This prior art process according to the FRG Patent No. 2.904,314 has a number of disadvantages. As it is specified in the Patent Specification, the isothermal character of the process is not achieved, since a great amount of heat is released at the inlet of the reactor as a result of polymerization and a gas phase is formed. This causes an increased pressure at the outlet of the tubular reactor. The increased pressure, in turn, results in a higher total resistance of the system. Therefore, the reactor productivity amounts to several hundreds kg/h which is considerably lower than the calculated theoretical value.

These difficulties can prove insurmountable for tubular reactors of a greater length (length of up to 800 mm, diameter of up to 100 mm).

The extension of the reactor's length simultaneously results both in an increased metalconsumption for the apparatus and in higher rates of power consumption for the process nearing corresponding parameters of processes carried out in cumbersome high-volume reactors. This nullifies the simplicity and other advantages of the processes for producing isobutylene polymers in tubular-type reactors.

The process has a disadvantage residing in rather low values of the desired product yield never exceeding 70%. This is due to the non-isothermal character of the process resulting in the formation of considerable amounts of low-molecular fractions.

The process according to FRG Patent No. 2,904,314 is also limited as regards the range of produced isobutylene polymers. It can yield only products with molecular masses only within the range of 500 to 5,000.

It is an object of the present invention to provide such a process which would make it possible to increase the yield of isobutylene polymers.

It is another object of the present invention to provide such a process for producing isobutylene polymers which would feature a high productivity.

It is still another object of the present invention to provide such a process which would ensure the production of isobutylene polymers with molecular masses within a wide range.

It is also an object of the present invention to provide such an apparatus for carrying-out the process for producing isobutylene polymers which would ensure an increased yield of polymers with a broadened range of molecular masses at a high product output.

It is a further object of the present invention to provide such an apparatus for producing isobutylene polymers which would enable a lowered metal- and power-consumption of the process equipment at a reduced occupied production floor areas.

These objects are accomplished by that in the production of isobutylene polymers with a molecular mass of not more than 150,000 in a tubular-type reactor by the process comprising admittance of, into the reaction zone of a reactor, of a stream of an isobutylene-containing feedstock having temperature of from 0 to -70"C and a stream of a solution of an acid catalyst, followed by polymerization of the feedstock in a flow of the reaction mass turbulently moving along the reactor, in accordance with the present invention the feedstock stream is admitted into the reaction zone at an angle of 30-120 to the axis of the reaction mass flow; the catalyst solution stream is fed into the reaction zone in at least two points so that the direction of the catalyst stream supply forms an angle of 30 to 90" to the feedstock supply direction; the reaction mass flow has a rate of from 0.3 to 15 m/s, temperature within the range of from 0 to 60"C and a pressure of from 1 to 5 atm.

Owing to the present invention an average yield of the polymeric products is abqut 90% at a unit productivity being by 15-20 times higher than the unit productivity attainable in practicing the processs according to the FRG Patent No. 2,904,314 and by 10 times higher (total productivity) than that of the process according to the FRG Patent referred to. The present invention makes it possible to process isobutylene polymers with a molecular mass within the range of from 300 to 150,000.

To ensure an additional thermostatting of the process and provide more favourable conditions for intermixing of the catalyst with the isobutylene-containing feedstock, according to the present invention it is desirable that the temperature of the stream of the catalyst solution be within the range of from 0 to -900C.

Furthermore, according to the present invention it is advisable that the catalyst solution be admitted into the reaction zone at a rate providing the catalyst concentration in the reaction mass equal to 0.01-0.5% by mass.

According to the present invention it is also advisable, to obtain isobutyiene polymers with a molecular mass of from 300 to 1,000, that the reaction mass flow have a temperature within the range of from 40 to 60"C.

It is also desirable, to obtain isobutylene polymers with a molecular mass of from 1,000 to 20,000 according to the present invention, that the reaction mass flow have a temperature of from 10 to 30"C.

Furthermore, according to the present invention, it is also advisable that, to obtain isobutylene polymers with a molecular mass of from 20,000 to 150,000, the reaction mass flow have a temperature ranging from 0 to 10 C.

It is desirable to carry out the process for producing isobutylene polymers with a molecular mass of not more than 150,000 in an apparatus comprising a tube with one-sided and separate input of the feedstock and the catalyst, wherein, according to the present invention, the inlet means for the feedstock and the catalyst are made in the form of socket pipes; the inlet socket pipe for the catalyst is located on the end face of the tube, directed inwardly and has on its cylindrical surface at least two openings with their axes forming an angle of 30 to 90" to the tube axis and the socket pipe for the feedstock supply is located on the cylindrical surface of the tube close to the end face thereof; the ratio of the tube to the diameter thereof being varied from 20:1 to 100:1 the ratio of the catalyst inlet socket pipe length to the tube length is 1:5 to 1:200 and the ratio of the catalyst inlet socket pipe pipe length to its diameter being 10-150:1.

Owing to the use of the apparatus according to the present invention the metal-consumption is reduced by 100 times and power-consumption-by 15-20%.

According to the present invention it is desirable that the tube have an additional nozzle secured to the inlet socket pipe for the catalyst and be embodied as 2-6 radially positioned at an angle to one another metallic plates rigidly connected therebetween on their length along the tube axis and forming reaction zones with the inner surface of the tube.

It is also advisable, according to the present invention, that the socket pipe for the feedstock supply be located at an angle of 30 to 1200 to the tube axis.

Furthermore, it is advisable that the socket pipe for the feedstock supply be oriented relative to the end face of the tube so that its axis be biased in respect of the tube axis.

Other objects and advantages of the present invention will now become more fully apparent from the following detailed description of the process for producing isobutylene polymers and the apparatus for implementation of this process, as well as examples illustrating this process and the drawings attached, wherein: Figure 1 shows the apparatus for carrying out the process for producing isobutylene polymers according to the present invention, elevation view; Figure 2 cross-section ll-ll in Fig. 1; Figure 3 an embodiment of the cross-section ll-ll; Figure 4 cross-section IV-IV in Fig. 1; Figure 5 ditto, side view.

The process for producing isobutylene polymers with a molecular mass of not more than 150,000 according to the present invention is effected by using, as the starting isobutylenecontaining feedstock, C4 hydrocarbon fractions, e.g. of the following composition, per cent by mass: propane- 1-2, propylene--0.6-1.2, iso-butane--20-55, n-butane- 1.7-3.0, a-butyl ene-0.4- 15, iso-butylene--20-60, trans-butylene-2-4, cis-buylene-3-7, divinyl-0. 1-2.

Prior to the use of starting isobutylene-containing feedstock is preliminarily subjected to rectification to remove resins and mechanical impurities, drying and cooling (ammonia cooler) to a temperature of O to 30"C.

As the starting isobutylene-containing feedstock it is possible to use also 20-30% solutions of individual isobutylene (99 5% purity grade) in chlorinated solvents (methylchloride, ethylchloride) previously cooled to a temperature within the range of from -30 to -90"C.

The process for producing isobutylene polymers is carried out in the presence of acid catalysts; as the latter solutions of aluminium chloride in ethyl chloride or methyl chloride are suitable in concentrations of from 1 to 3%; solutions of aluminium chloride in toluene, xylene and/or mixtures of aromatic hydrocarbons with a concentration of up to 40%; a solution of ethylaluminium dichloride in gasoline, ethylaluminium sesquichloride in gasoline, solution of complexes of ethylaluminium chloride with water or alcohols in gasoline of a concentration of 1-20%; boron trifluoride and esters thereof with a concentration of 1-5%.

Solutions of the catalysts prior to their use in the process are cooled to a temperature within the range of from 0 to -900C by means of ammonia and/or ethylene coolants.

The starting isobutylene-containing feedstock and the catalyst are supplied into the reaction zone in the form of separate streams; the directions of their feed according to the present invention form an angle of from 30 to 90" thus ensuring an effective intermixing of the streams.

Furthermore we have found that, to ensure a rapid and effective inter-mixing of the starting feedstock with the catalyst, the catalyst solution stream should be fed into the reaction zone in at least two points at a speed ensuring the catalyst concentration in the reaction mass equal to 0.01-0.5% by mass.

As it is well known, the provision of a high-efficiency process for producing isobutylene polymers contemplates high speeds of the stream of the isobutylene-containing feedstock. According to the present invention it is necessary that the speed of the general flow of the catalyst and feedstock in the reaction zone be within the range of from 0.3 to 15 m/s which is caused by the necessity to provide a turbulent flow of the reaction mass. We have found that at the speed of the reaction flow of less than 0.3 m/s the turbulization is ineffective, while in the case of turbulence in the reaction flow its rates above 15 m/s result in a reduced conversion degree which is explained by a shortened effective time of residence of the isobutylene-containing feedstock in the reaction zone.

The degree of turbulization equal to about 104 according to the present invention is evaluated by standard formulae, e.g. by the Reynolds criterion. The minimum value of the Reynolds criterion calculated through the values of linear velocity, flow density, dynamic factor of the viscosity of the medium and the tube diameter is equal to about 104 thus indicating a turbulent character of the flow.

In the process disclosed in the FRG Patent No. 2,904, 314 the use of high linear velocities of the reaction mass flow (up to 20 m/s) as a turbulent character of its flow does not ensure a high productivity which would correspond to the specified velocity and turbulence. The gas phase formed in the inlet zone of the reactor causes an increased resistance of the system due to difficulties in the heat removal. As a result, despite the preset high linear velocities of the flow the polymeric product appears at the outlet from the system only after several dozens of minutes rather than after several seconds (as it follows from a simple calculation). Therefore, at linear velocities mentioned in the FRG Patent No. 2,904,314 a high-productive stationary character of the process is not attained.As a result, the productivity of the process disclosed in the FRG Patent referred to is only of about several hundreds of kg of the polymer per hour, whereas in the process according to the present invention it is equal to several tons of the polymer per hour.

The effect of turbulization necessary for implementation of the process according to the present invention at a rate of the reaction mass flow ranging from 0.3 to 15 m/s is due to the fact that, as it has been already mentioned hereinbefore, the stream of the isobutylene-containing feedstock is admitted into the reaction zone at an angle of 30 to 1200 to the direction of the reaction mass flow.

High linear velocities of the movement of the feedstock stream in combination with high rates of the polymerization process provide for the necessity of a quick and effective intermixing of the catalyst stream with the feedstock stream. This requirement is fulfilled by supplying the catalyst solution stream into the reaction zone in the mode specified hereinbefore.

The reaction in a high-rate turbulent flow is characterized by an instantaneous reduction of the reaction volume due to a rapid polymerization of isobutylene and intensive heat release owing to the exothermal character of the reaction. In combination they result in a sharp increase in the flow turbulization, thus favouring completion of the reaction. The heat evolved in the reaction is consumed for evaporation of a portion of the feedstock. At a temperature of the reaction flow within the range of from 0 to 60"C under a pressure of 1-5 atm it is possible to control the boiling and an effective removal of the heat evolving in the reaction, as well as to ensure a process character approaching an isothermal one (temperature fluctuations across the reaction mass flow are +2.5"C) despite the absence of an external thermostatting.

In the process according to the FRG Patent No. 2,904,314 the polymerization reaction character close to the isothermal is not ensured. According to this Patent, pressure in combination with the reaction temperature are applied so that the polymerization process proceeds in the liquid phase and to very high degrees of conversion. This technique avoids the possibility of release the polymerization reaction heat by boiling the starting feedstock and causes the temperature difference at the beginning and the end of the reaction flow and, hence, an impaired quality of the polymeric product.

The variation of temperature and pressure of the reaction mass flow within the above-specified limits ensures, as it has been proven by the inventors, in addition to maintaining the isothermal character of the process, the possibility of controlling properties of the final products (molecular mass, molecular-mass distribution) at a high total conversion of the feedstock (up to 95%).

A distinctive feature of the control of molecular-mass characteristics of isobutylene polymers in polymerization in a high-speed turbulent flow resides in a high sensitivity of the process to relatively small variations of temperature and pressure.

Thus, according to the present invention, to produce isobutylene polymers with a molecular mass of from 300 to 700, the reaction mass flow should have a temperature within the range of from 50 to 60"C; for the production of isobutylene polymers with a molecular mass of from 800 to 1,000 the reaction mass flow should have a temperature within the range of from 45 to 50"C. According to the present invention, to produce isobutylene polymers with a molecular mass of from 1,000 to 5,000 the reaction mass flow should have a temperature within the range of from 40 to 45"C, while for the production of isobutylene polymers with a molecular mass of from 5,000 to 10,000 the reaction mass flow temperature should be equal to 35-40"C and for the production of isobutylene polymers with a molecular mass of from 10,000 to 20,000 the reaction mass flow temperature should be equal to 30-35"C. According to the present invention, to produce isobutylene polymers of a molecular mass within the range of from 20,000 to 50,000 the reaction mass flow temperature should be equal to 20-30"C and for the production of isobutylene polymers of a molecular mass of 50,000 to 150,000 the reaction mass flow should have a temperature within the range of from 0 to 20"C.

The process for producing isobutylene polymers according to the present invention should be performed in a reactor made as a tube 1 (Figs. 1 and 2, 3, 4, 5) with the ratio of its length to its diameter ranging from 20:1 to 100:1. This ratio of the tube length to the diameter thereof ensures an optimal time of residence of the components in the reaction zone at predetermined linear velocities (0.3-15 m/s) of the turbulent flow of the reaction mass with the account of kinetics or duration of the reaction (which is equal to fractions of a second). At ratios of the tube length to its diameter below 20: 1 the acceptable completeness of the reaction is not reached, i.e. the productivity of the apparatus is lowered.A ratio of the tube length to its diameter above 100:1 does not provide any noticeable effect on completeness of polymerization (monomer conversions are high enough even without it) but increases probability of occurring of side reactions impairing the resulting polymer's quality and unreasonably adding up to the metalconsumption of the apparatus.

The tube I has an inlet socket pipe 2 (Figs. 1, 2, 3, 4 and 5) for the catalyst supply which is provided at the end face of the tube 1 and is extended inwardly in respect of the latter.

According to the present invention, the ratio of the pipe 2 length to the length of tube 1 should be within the range of from 1:5 to 1:200, while the ratio of the pipe 2 length to its diameter should be equal to 10-150: 1. This condition makes it possible to ensure a uniform distribution of the catalyst within the bulk of the isobutylene-containing feedstock and create the required turbulization of the flow.

At low ratios (below 10) the socket pipe 2 for the supply of the catalyst exerts a high hydrodynamic resistance to the feedstock stream and thus limits the productivity of the tubular reactor. At higher ratios (above 150) the socket pipe 2 for the catalyst supply does not ensure the required volume concentration of the catalyst in the reaction zone, i.e. its effective distribution. This also lowers productivity of the apparatus due to a decreased conversion of the monomer.

The ratio between the linear dimensions of tube 1 and the catalyst supply pipe 2 within the range of from 5:1 to 200: 1 makes it possible to control the polymerization process due to a controlled distribution of the catalyst along the feedstock stream which, in combination with the advisable temperature and pressure of the feedstock stream, ensures the production of polymers within a broad range of molecular mass values and molecular-mass distributions. Lesser difference in the linear dimensions of the tube and the catalyst inlet pipe (ratios below 5:1) does not ensure an isothermal character of the process (temperature fluctuations exceeding +2.5 ) and results in a predominating formation of low-molecular products.A surpassed upper limit of the ratio value of 200:1 is accompanied by a reduction of the useful space of the tubular reactor 1 and an increase of the system resistance. This brings about such disadvantages as an increased metal consumption, higher energy consumption, difficulties in maintaining stable process conditions which is totally undesirable.

The absence of a special unit for the catalyst admittance into the feedstock stream, according to the prototype process and apparatus, is one of the basic reasons of the drastic difference in the attained productivity in the process according to the present invention and that of the prototype.

According to the present invention, it is advisable that a nozzle 3 be provided on the inlet socket pipe 2 for the catalyst (Figs. 4 and 5) which nozzle be made in the form of 2 to 6 metal plates 4 (Fig. 5) radially positioned at an angle to one another, rigidly secured on their length along the axis of tube 1 and forming reaction zones 5 (Fig. 5) with the inner surface of tube 1.

The presence of this nozzle provides a favourable effect on a uniform distribution of heat and the removal of the reaction heat from the stream, as well as on the reaction of polymerization creating conditions close to isothermal ones.

It is obvious that a greater number of plates in the nozzle is desirable. However, this number should be limited by six plates, since at a greater number the resistance to the feedstock stream is sharply increased and the reactor productivity is lowered.

According to the present invention, on the surface of the socket pipe 2 located inside the tube 1 at least two openings 6 (Fig. 1) should be provided with their axes forming an angle a of from 30 to 90 to the axis of the tube 1.

An inlet pipe 7 (Figs. 1, 2 and 3) is also provided on the tube 1 for the admission of the isobutylene-containing feedstock which is located on the cyindrical surface of the tube 1 close to its end face. An embodiment of the present invention is also possible, wherein the pipe 7 is positioned at an angle ss to the axis of the tube 1 equal to 30-120" (Fig. 1).

Furthermore, according to the present invention, it is also possible to position the pipe 7 on the tube 1 so that it be oriented relative to the end face of the tube 1 in such a manner that its axis is biased relative to the longitudinal axis of the tube 1 (Fig. 3).

We have found that this design ensures a higher degree of turbulization of the reaction mass flow by more than 50% thus favouring a more uniform distribution of the catalyst within the reaction mass bulk and, hence, resulting in a higher productivity.

At an angle of the feedstock admission of less than 30 concurrent streams of the feedstock and catalyst are formed which results in worsened conditions of the catalyst distribution within the feedstock stream, thus lowering the yield of the final product.

At an angle above 1200, the origination of countercurrent streams becomes dominating which results in the formation of dead zones. This, in turn, causes excessive power consumption and a lower productivity.

For the withdrawal of the desired product an outlet socket pipe 8 (Fig. 1) is provided on the end face of the tube 1 opposite to that on which the inlet socket pipe 2 is positioned.

The apparatus according to the present invention operates in the following manner.

An isobutylene-containing feedstock cooled to a temperature within the range of from 0 to -900C is admitted into the reactor-tube 1 through the inlet socket pipe 7 at a speed of from 0.3 to 15 m/s. A solution of a catalyst at a temperature within the range of from 0 to -90"C is fed into the reactor-tube 1 through the inlet socket pipe 2 in an amount ensuring a complete conversion of the monomer and a stable operation of the reactor.

The degree of turbulization of the reaction mass flow and its temperature are adjusted by the angle ss of inclination of the socket pipe 7 to the axis of the tube 1, by biasing its axis relative to the axis of the tube 1, as well as by perforation of the socket pipe 2 and by pressure of the reaction mass flow. The operation conditions of the reactor are controlled by instruments 9 and 10 (Fig. 1) recording variations of the reaction mass flow temperature and its pressure respectively.

The resulting isobutylene polymer is discontinuously sampled by means of a sampler 11 (Fig.

1) for the purpose of the control of is molecular-mass characteristics.

The final product is discharged from the reactor-tube 1 through the outlet socket pipe 8 and delivered to the subsequent outgassing.

Examples 1-13 A commercial fraction of C4 hydrocarbons is used for polymerization; it contains 0.6-12% of propylene, 1-2% of propane, 47-54% of isobutane, 1.3-3% of n-butane, 0.4-1% of a-butene, 40-55% of isobutylene, 0.2-1.2% of fi-butylenes, 0.2-0.3% of butadiene. As the catalyst, a solution of aluminium chloride in chlorethyl of the concentration of 1.5% by mass is used. The reaction is conducted in an apparatus shown in Fig. 1 having the following dimensions: tube length-200 cm, tube diameter-8 cm, length of the catalyst inlet socket pipe-20 cm, diameter of the catalyst inlet socket pipe .25 cm (the ratio of the tube length to the diameter thereof is 25:1, the ratio of the length of the catalyst inlet socket pipe to its diameter is 15:1, the ratio of the length of the catalyst inlet socket pipe to the tube length is 1:10).

The feedstock is admitted into the reactor through a socket pipe positioned at an angle (ss) of up to 90 to the tube axis. The inlet socket pipe for the catalyst supply ensures the admission of the catalyst solution at an angle (a) of 90 C to the feedstock stream. The process control is effected by temperature, pressure in the reaction zone and chromatographically by the monomer conversion value.

The reaction mass after the reactor is treated with water (alcohol) and subjected to fractionation to separate the unreacted components of the feedstock and light fractions. The polymers are analyzed for their molecular mass (cryoscopy, viscosimetry), molecular-mass distribution (MMD) (gel-chromatography); low-molecular polymers are also analyzed for the degree of unsaturation (by measuring their iodine number).

The results of tests for polymerization of the fraction of C4-hydrocarbons under the pressure of 3.2 atm are shown in Table 1 hereinbelow.

Table 1 No. Catalyst stream Reaction mass Conver- Molecu sion,% lar Rate, % by Temperature, Rate Temperature, by mass mass mass C m/s C x10-2 l/h 1 2 3 4 5 6 7 8 1 0.05 0.015 0 0.35 60 79.4 420 2 0.I 0.03 0 0.35 60 83.I 540 3 3.4 3,13 0 0.35 60 94.3 310 4 0.4 0.13 -10 0.35 51 91.7 760 5 0.4 0.13 -15 0.42 41 90.6 1,100 6 0.4 0.13 -30 0.42 32 89.3 2,700 7 o.a O.2 -35 3.42 21 97.6 8 0.@ 0.2 -50 0.42 17 98.4 15,000 9 0.8 0.2 -70 0.42 12 96.5 20,000 10 0.6 0.2 -90 0.42 5 94.3 63,000 11 0.6 0.2 -90 0.54 4 96.9 94,000 12 0.6 0.3 -90 0.54 0 94.0 61,000 13 1.5 0.5 -90 0.54 0 97.2 36,000 Examples 14-17 In polymerization in an apparatus similar to that described in the foregoing Examples 1 to 13 under conditions of Example 9 but with other angles of admission of the catalyst solution stream relative to the feedstock stream the following results are obtained (see Table 2 hereinbelow).

Table 2 No. Catalyst stream Reaction mass flow Angle α, Conver- Mole sion, cular Rate, Tempera- Rate, Temperature, degrees mass ture, % by x10-2 m/s C l/h C mass 1 2 3 4 5 W 7 3 14 0.6 -70 0.42 12 70 96.0 21,000 15 0.6 -70 0.42 11 63 95.7 20,700 16 0.6 -70 0.42 11 45 90.1 20,000 17 0.6 -70 0.42 10 30 89.7 24,300 Examples 18-21 Polymerization carried out in an apparatus similar to that described in Examples 1 to 13 under conditions of Example 8 but with other angles of positioning of the feedstock inlet socket pipe has given the following results (Table 3).

Table 3 No. Catalyst stream Reaction mass flow Angle ss , Feed- Molecu degrees stock lar Rate, Tempera- rate, Tempera- m/s ture, C con- mass x10-2 ture, C 1/h ver sion, % by mass 1 2 -- 3 4 5 6 7 8 18 0.6 -50 0.42 11 30 85.9 24,000 19 0.6 -50 0.42 15 45 94.7 21,300 20 3.5 -50 s.42 15 6 96.3 21,300 21 0.6 -50 0.42 20 120 87.3 17,300 Examples 22-26 Polymerization in an apparatus similar to that described in Examples 1 to 13 under conditions of Example 10 but at other speeds of the reaction mass flow in the reactor has given the following results (Table 4).

Table 4 o. Catalyst stream Reaction mass flow Feedstock Molecular conversion, mass Rate, Tempera- rate, Temperature, % by mass x10-2 ture, C m/s C l/h 1 2 3 4 5 6 7 22 0.6 -90 0.7 8 98.3 86,000 23 0.6 -90 1.0 8 98.6 84,000 24 0.6 -90 3.0 5 95.3 90,700 25 0.6 -90 10.0 3 94.0 103,000 26 0.6 -90 15.0 0 89.2 112,000 Examples 27-31 Polymerization in an apparatus similar to that described in Examples 1 to 13 under conditions of Example 5 herein before has given the following results depending on the pressure values of the reaction mass flow (Table 5).

Table 5 no. Catalyst stream Pressure of Feedstock Molecular Rate, Temperature, the reaction conversion, mass x10-2 C mass flow % by mass l/h 1 2 3 4 5 6 27 0.4 -15 1.0 90.7 4,300 28 0.4 -15 2.1 96.5 1,370 29 0.4 -15 3.4 98.1 1,000 30 0.4 -15 3.9 99.0 620 31 0.4 -15 5.0 98.9 390 Examples 32-35 Polymerization carried out in an apparatus similar to that described in Examples 1 to 13 under conditions of Example 9 but using an inlet socket pipe for the catalyst provided with a nozzle has given the following results depending on the number of plates in the nozzle (Table 6).

Table 6 No. Number of plates Feedstock Molecular MMD values, in the nozzle conversion, mass (Mw/Mn) 7. by mass 1 2 3 4 5 32 0 94.2 23,000 9.1 33 2 96.5 25,300 4.7 34 4 98.7 26,3k)0 2.9 35 6 99.1 27,200 2.1 As it is seen from the data of Table 6 the number of plates in the nozzle affects the molecular-mass distribution (MMD) of the resulting polymers.

Examples 36 to 39 Polymerization in an apparatus similar to that described in Examples 1-13 under conditions of Example 9 but as different ratios of the tube length to its diameter (for the constant ratio of the length of the catalyst inlet socket pipe to the tube length of 1:20) has given the following results shown in Table 7 hereinbelow.

Table 7 No. Ratio of tube length Fedstock conver- Molecular to its diameter sion, % by mass mass 1 2 3 4 20:1 39.7 24,030 37 5ù:1 92.3 25,000 38 75:1 96.5 24,300 39 100:1 98.1 24,900 Examples 40-45 Polymerization carried out in an apparatus similar to that described in Examples 1 to 13 but with a different ratio of the length of the catalyst inlet socket pipe to the tube length has given the following results depending on the value of this ratio (see Table 8).

table 8 o. Ratio of the Iength Feedstock Molecular Remark: Ex of the catalyst in- conversi- mass periments con let socket pipe to on, ,"'o by ducted under the tube length mass conditions oi Examples (Tab. 9) 1 2 3 4 5 40 1:5 96.3 120,000 10 41 1:15 94.7 73,000 10 42 1:20 95.9 23,70') 9 43 ù 97.1 8,000 9 44 1:150 96.8 1,500 5 45 1:200 98.4 1,000 5 Examples 46 to 50 Polymerization carried out in an apparatus similar to that described in Examples 1 to 13 hereinbefore, but with the exception that the ratio of the length of the catalyst inlet socket pipe to its diameter at the tube length of 3 m and tube diameter of 12 cm has given the following results depending on the value of this ratio (Table 9).

Table 9 No. ratio of the length of the Feedstock con- Molecular catalyst inlet socket version, % by mass pipe to its diameter mass 1 2 3 4 46 1u:1 93.1 910 47 20:1 98.7 1,710 48 5ù:1 94.2 2,4X 49 100:1 90.9 2,700 50 150:1 97.4 2,600 According to the data of an iodometric analysis, the resulting polymers have a degree of unsaturation close to 1 (i.e. one double bond per molecule).

Claims (12)

1. A process for producing isobutylene polymers with a molecular mass of not more than 150,000 in a tubular-type reactor comprising supplying into a reaction zone of the reactor a stream of an isobutylene-containing feedstock having temperature within the range of from 0 to -70 C at an angle of from 30 to 120 to the axis of the reaction mass flow simultaneously with supplying a stream of a solution of an acid catalyst in at least two points, the direction of the catalyst stream supply forming an angle of 30 to 90" to the feedstock stream, the subsequent polymerization of the feedstock in the reaction mass flow turbulently moving along the reactor at a rate of from 0.3 to 15 m/s, temperature of from 0 to 60 C and under a pressure of from 1 to 5 atm.

2. A process for producing isobutylene polymers according to Claim 1, wherein the catalyst solution stream has a temperature within the range of from 0 to -90 C.

3. A process for producing isobutylene polymers according to Claim 1, wherein the catalyst solution is admitted into the reaction zone at a rate ensuring concentration of the catalyst in the reaction mass flow of from 0.01 to 0.5% by mass.

4. A process for producing isobutylene polymers with a molecular mass of from 300 to 1,000 according to Claim 1, wherein the reaction mass flow is maintained at a temperature of from 40 to 60"C.

5. A process for producing isobutylene polymers with a molecular mass of from 1,100 to 20,000 according to Claim 1, wherein the reaction mass flow has a temperature of from 10 to 30"C.

6. A process for producing isobutylene polymers with a molecular mass of from 20,000 to 150,000 according to Claim 1, wherein the reaction mass flow is maintained at a temperature of from 0 to 100C.

7. An apparatus for carrying out the process for producing isobutylene polymers according to Claim 1, comprising a tube provided with an inlet socket pipe for the catalyst supply positioned on the end face of the tube and directed inwardly having on its cylindrical surface at least two openings with their axes forming an angle of from 30 to 90 to the axis of the tube, and an inlet socket pipe for the feedstock supply positioned on the cylindrical surface of the tube close to the end face thereof, the ratio of the tube length to the diameter thereof being ranged from 20:1 to 100:1, the ratio of the length of the inlet socket pipe for the catalyst supply to the tube length being ranged from 1:5 to 1:200 and the ratio of the length of the inlet socket pipe for the catalyst supply to the diameter thereof being equal to 10-150: 1.

8. An apparatus according to Claim 7, wherein the tube is additionally provided with a nozzle mounted on the inlet socket pipe for the catalyst supply and made in the form of 2 to 6 metal plates radially positioned at an angle to one another and rigidly connected by their lengths along the tube axis and forming reaction zones with the inner surface of the tube.

9. An apparatus according to Claims 7 and 8, wherein the inlet socket pipe for the feedstock supply is positioned at an angle of 30 to 1200 to the tube axis.

10. An apparatus according to Claims 7 to 9, wherein the inlet socket pipe for the feedstock supply is oriented relative to the tube end face so that its axis is biased in respect of the axis of said tube.

11. A process for producing isobutylene polymers according to the foregoing Claims 1 to 6, substantially as described in the Specification and Examples hereinbefore.

12. An apparatus for carrying out the process for producing isobutylene polymers according to Claims 7 to 10, substantially as described in the Specification and shown in the drawings attached.