CS211705B1

CS211705B1 - Method of processing butan/butene fraction together with methanol

Info

Publication number: CS211705B1
Application number: CS190478A
Authority: CS
Inventors: Jaromir Vybihal
Original assignee: Jaromir Vybihal
Priority date: 1978-03-24
Filing date: 1978-03-24
Publication date: 1982-02-26

Description

(54) A method for treating the butane-butene fraction with methanol

This invention relates to the treatment of a butane-butene fraction resulting from the pyrolysis of hydrocarbons with methanol using a molded catalyst based on a sulfonated styrene-divinylbenzene copolymer and thermoplastics. ·

The butane-butane fraction resulting from the pyrolysis of hydrocarbons is a mixture of butadiene, isobutylene, butene-1, butenes-2, isobutylene, n-butane and minor amounts of C2-, C3- and C1-hydrocarbons, methylacetylene, vinylacetylene, ethylacetvene and possibly. S- and N-compounds. The butane-butene fraction is conventionally treated by subjecting it to low-temperature hydrogenation to hydrogenate the acetylenic compounds and then extract the butadiene therefrom. The butane-butene fraction after butadiene extraction contains isobutylene as the main component, which is obtained therefrom by extraction of about 45% H2SO4. Another method consists in oligomerization, using various catalysts, including cation exchangers, whereby the major part of isobutylene is converted to di- and triisobutylene.

Another method is to hydrate isobutylene with water to form tert-butyl alcohol using ion exchange catalysts. Another method is the condensation of isobutylene with formaldehyde to 4,4-dimethyl-1,3-dioxane, which is then further processed to isoprene. Here too, cation exchangers can be used in the condensation of isobutylene with formaldehyde.

Another process for treating the butane-butene fraction consists in adding isobutylene with an alcohol to form ethers, eg, isobutylene contained in the C4-fraction with methanol, to form methyl-tert. butyl ether using a catalyst based on sulfonated styrene-divinylbenzene copolymers.

In all of these processes, it is preferable to use cation exchange resins, the essence of which is strongly acidic sulfonated polystyrene resins of crosslinked divinylbenzene copolymer. These cation exchangers in commercial form contain about 50% solvent or are solvent-free by evaporation. These cation exchangers are produced in fine-grained particles, predominantly ball-shaped, with dimensions of 0.1 to 1.0 mm. When using these cation exchangers for catalytic purposes, the reaction usually takes place in stirred reactors with fine-grained or powdered cation exchangers, using a catalyst concentration in the range of 0.1 to 100% by weight, based on the dry catalyst base. A disadvantage of this use of cation exchangers is the fact that the catalyst must be separated from the reaction products. recycled to the process or precautions must be taken in the reactor to prevent the cation exchanger from entraining with the product from the reactor at its outlet, or to be included in the process of offsetting, filtering or centrifuging the catalyst from the reaction products.

When using a fine-grained cation exchanger of 0.1 to 1.0 mm in a fixed bed in the reactor, large hydraulic resistances occur in the equipment and the cation exchanger has to be poured into the reactor in low layers, specially arranged operating equipment and reduced flow rate to avoid flooding. of the catalyst.

However, it has now been found that these problems can be overcome by the use of a sulphonated cation exchange catalyst, styrene-divinylbenzene copolymers formed into the desired shape and size, satisfying both mechanical strength and porosity. The process for treating the butane-butene fraction with methanol under the catalytic action of cation exchangers consists in that the butane-butene fraction contains 20 to 10 wt. % of isobutylene is contacted with a cation exchanger based on sulfonated styrene divinylbenzene copolymers formed with 10 to 50 wt. thermoplastic materials such as polyethylene, polypropylene, polybutene-1 or its copolymers or polyvinyl chloride, optionally sulfonated. Other binders such as activated carbon, NaCl and the like may be present.

A strongly acidic cation exchange catalyst composed of styrene copolymers having 4 to 20 wt. divinylbenzene containing at least one -SO 3 H group on the benzene ring. or a -COOH or fluorinated group comprising F or having a sulfonated polyphenol base and forming a thermoplastic bonded to the desired shape and size. The bonding is accomplished by heating to a suitable temperature and pressure such that the formed catalyst particles have sufficient mechanical strength as well as an undiminished surface and high porosity. For the treatment of the butane-butene fraction with methanol to methyl tert-butyl ether formed cation exchangers with plastic, such as polyethylene, polypropylene, copolymers of ethylene with propylene, polybutene-1, copolymer of ethylene with butene-1 or sulfonated polyethylene, sulfonated polypropylene are suitable. , sulfonated polyvinyl chloride and the like.

These sulfonated copolymers of polyvinyl-aryl compounds with sulfonated sulfonic acid compounds. mono. The vinylaryl compounds consist of divinylbenzene, divinyltoluene, divinylethylbenzene, isopropenylbenzene, divinylchlorobenzene, styrene, vinyltolueh, vinylethylbenzene, etc. The amount of thermoplastic material added to the cation exchanger is above 10 wt%, preferably in the range of 25 to 50 wt%. thermoplastics or sulfonated thermoplastics, optionally with the addition of NaCl and the like. The finished catalysts formed from the above components can be prepared in H ⁺ or Na ⁺ form and are activated by washing with dilute HCl and water before use and converted to H ⁺ form and stripped of all Na ions. They can further be thermally activated at a temperature of 80 to 120 ° C and dehydrate predominantly or completely dehydrated to below 2% by weight. HgO. Further, they may be washed prior to use such as methanol, hydrocarbons and the like.

The catalysts thus prepared have a highly developed inner surface and a high porosity, the ion exchange capacity of these catalysts being about 3 to 4.2 kg eq / g dry catalyst. Furthermore, they have good thermal stability and activity in the range of 70 to 120 ° C. The catalyst may be in the form of rollers, extrudates, rings, tubes, etc., of different diameters, preferably 1-10 mm, and of different lengths. The catalyst in the reactor imposes virtually no resistance to the flowing reactants and can be poured into the reactor or distillation columns as their filling at a height of several meters, without causing greater hydraulic resistance.

When using a catalyst of this type, the butane-butene fraction resulting from the pyrolysis of hydrocarbons containing butadiene as the main constituent, isobutylene, butene-1, butene-2, isobutane, n-butane or butane-butene fraction is preheated together with methanol. in a preheater and from there goes to a reactor in which the catalyst is in the form of extrudates of 2.5 mm diameter and about 5-10 mm in length, packed in a fixed catalyst bed and through which either the butane mixture in the gaseous or preferably liquid phase is passed. butene fraction and methanol in an amount of 0.5 to 20 v / v / hr. The temperature in the reactor is maintained at 60 to 120 ° C, preferably 80 to 90 ° C, and a pressure of 0.5 to 2.5 MPa, preferably 1 to 2 MPa. The reaction product is passed through a condenser to a separator and thereafter to a distillation column where unreacted C--hydrocarbons entrained with methanol in an amount of about 0.4% by weight are separated overhead, so that this C4-fraction must be washed with water before further processing.

From the bottom of the distillation column, methyl tert-butyl ether is obtained with less methanol, the content of which depends both on the conversion of isobutylene and on the amount of methanol added to the feedstock at the reactor inlet. The effluent from the bottom of the distillation column, containing predominantly methyl tert-butyl ether and methanol, can be used directly or after further treatment as high-octane components for gasoline. However, methyl tert-butyl ether can be distilled from this mixture as an azeotrope with methanol and then used in autobenzine or processed into pure methyl tert-butyl ether, for example by azeotropic distillation with n-pentane or water washing and the like.

The conversion of the isobutylene contained in the butane-butene fraction with methanol depends on the activity of the catalyst used, but also on the ratio of methanol to isobutylene entering the reactor. If the molar ratio of methanol to isobutylene is greater than 1, then the isobutylene conversion is higher. However, a wide range of methanol to isobutylene molar ratio can be employed, e.g. 0.8 to 2.5. The starting material entering the catalyst must not be contaminated with metal substances, amines, NH 3. etc. that reduce its activity. Preferably, the butane-butene fraction does not reach the acetylenic compound and above 1 wt. butadiene. Also, larger amounts of free, undissolved water, polymers, or N-compounds can reduce the activity of the catalyst.

He did

In a reactor consisting of a steel tube of 1 m length and 30 mm diameter, equipped with a temperature measuring tube and a jacket whose upper part served as a preheater, while the lower part containing the catalyst was thermostatized with circulating water, was charged with 100 ml of catalyst. extrudates with a diameter of 2.2 mm and a length of 5 to 10 mm. The catalyst consisted of 70 wt. % of sulfonated styrene-divinylbenzene copolymers and 30 wt. parts of polyethylene. A mixture of anhydrous methanol and butane-butene fraction, after butadiene extraction in a 1: 1.5 mass ratio, was fed to the reactor in an amount of 3 vol. Feedstock per 1 vol. Catalyst per hour. The reaction product from the reactor was passed through a condenser to a separator and from there to a distillation column where the unreacted C4-fraction was distilled overhead and a mixture of methyl-tert-butyl ether and methanol was distilled at the bottom of the column. The composition of the starting butane-butene fraction after its reaction is shown in the table:

C4 fraction after butadiene extraction C4 ~ frakee after reacting C8-C8-hydrocarbons, % wt. 0.8 1.7 isobutane % wt. 4.0 6.7 n-butane % wt. 8.7 14.8 butene-1 % wt. 24.4 40.7 isobutylene % wt. 45.5 5.9 trans-butene-2 % wt. 9.6 16.8 cis-butene-2 % wt. 6.3 1.1, 8 butadiene-1,3 % wt. 0.5 0.9 Cj-hydrocarbons % wt. 0.2 0.7

Ether fraction composition approx. 50 to 60 ° C:

density at 20 ° C 0.750 methyl tert-butyl ether% w / w 91.5 methanol% wt. 8.5

To evaluate the motor properties of the ether fraction obtained by treating the butane-butene fraction with methanol with the above catalyst, autobenzine was prepared from a reforming product and an ether fraction of 50 to 60 ° C, the composition and properties of which are summarized in the following table:

product catalytic.

Claims

SUBJECT OF THE INVENTION

A process for treating a butane-butene fraction with methanol under the catalytic action of cation exchangers, characterized in that the butane-butene fraction containing 20 to 50 wt. % of isobutylene, is contacted with a cation exchanger based on a sulfonated styrene divinylbenzene copolymer formed with at least 10 wt. thermoplastic materials, such as polyethylene, polypropylene, polybutene-1, or copolymers thereof, or polyvinyl chloride, optionally sulfonated, to particles of a size above 1.5 mm.