Preparation method of methyl-terc.buthylether

(54) A method for the preparation of methyl inter-butyl ether

2 . A process for the preparation of methyl tert-butyl ether; % of methanol and isobutene in the 'presence of sulfonated' styrene-divinylbenzene resins as catalyst is carried out in a tray fractionation column where the catalyst trays are separated from each other by either several fraction trays or one fraction tray and the catalyst trays are immersed in a methanol-containing liquid. Methanol is fed in the region of the upper end of the column and the hydrocarbon feed of the isobutene is fed at a point where at least two catalyst bed trays are above this point a.

at least one floor with a catalytic bed. is below this place. The process is carried out at a pressure of 0.5 to 10 bar. The methyl tert-butyl ether obtained is removed from the bottom of the column.

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The present invention relates to a process for the preparation of methyl tert-butyl ether from isobutene and methanol in the presence of sulfonated styrene-divinylbenzene resins as a catalyst in a trayed column.

The process for preparing the methyl tert-butyl ether of the present invention, as described in detail below, can also be applied to the production of all other tertiary alkyl ethers since the differences between the boiling points of the starting materials used and the products formed are within the same range of values.

Methyl tert-butyl ether is prepared according to the prior art by reacting isobutene, which is usually contained in a variable percentage in the C4 hydrocarbon fraction, with methanol in the presence of a suitable catalyst, which is usually composed of sulfonated styrene-divinylbenzene resins, usually at ranging from ambient temperature to about 100 degrees Celsius.

The isobutene starting component is not normally prepared on an industrial scale and therefore preparation using a C4 isobutene-containing hydrocarbon fraction will be considered in the present case.

The above reaction is an equilibrium reaction, and if the amount of methanol used is close to the stoichiometric amount, then the isobutene conversion is 90% or even higher, at temperatures that provide an acceptable reaction rate.

Where a higher conversion is required, an excess of methanol must be used, and the excess must then be separated from the reaction product and recycled, in which case the conversion is slightly higher than 95 ° / o under acceptable conditions, or alternatively In another embodiment, the reaction product may be separated and the remaining mixture fed to a second reaction stage where about 99% conversion can be achieved again under approximately stoichiometric conditions.

However, the problem is that the C4 hydrocarbon fraction needs to be vaporized twice, and two reactors and two distillation columns are required to increase investment and operating costs. According to the latest prior art document [European patent no. 8860 of 1980) proposes to overcome the above problems by applying a process comprising feeding a mixture comprising isobutane and methanol to a distillation column packed with a catalyst suitable for the preparation of methyl tert-butyl ether, whereby said catalyst functions as a packed distillation column. , forming methyl t-butyl ether and separating methyl t-butyl ether from the Cd components.

However, the process of the aforementioned patent has some serious drawbacks due to the fact that the catalyst functions as a distillation column of the distillation column and must therefore meet certain requirements, and in particular the requirement for low pressure drop. For this reason, the catalyst is used as a strip-forming filler which allows sufficient space for conducting vapor and liquid. A disadvantage of the process proposed in this way is that such a catalyst is difficult to prepare and load into the column.

The method described in the above-mentioned European patent also shows the drawback that the continuous phase within the column is represented by the vapor phase, whereas the dispersed phase is the liquid phase, resulting in low methyl tert-butyl ether yields since the reaction takes place practically in the vapor phase.

This also leads to the possible formation of substantial amounts of dimer, since an insufficient amount of methanol occurs in the vapor phase.

Unexpectedly, it has been found that all of the above-mentioned drawbacks can be overcome by carrying out both the reaction leading to the formation of methyl tert-butyl ether and the separation of this component from the hydrocarbons and compounds present in a single-storey state. a fractionation column in which some of the trays are equipped with a catalytic bed, said catalyst being based on sulfonated styrene-divinylbenzene resins and in the form of spheres, which is suitable for the preparation of methyl tert-butyl ether.

The process for preparing methyl tert-butyl ether from methanol and isobutene in the presence of sulfonated styrene-divinylbenzene resins as catalyst consists in reacting the formation of methyl tert-butyl ether and separating methyl tert-butyl ether from hydrocarbons and compounds. accompanying it takes place in a tray fractionation column, where the catalyst bed trays are separated from each other by either several fraction trays or one fraction tray, wherein the number of trays containing the catalytic bed is at least three. The catalyst beds are filled with a catalyst in the form of spheres with a diameter ranging from 0.5 to 1 millimeter and during the process the beds are immersed in a methanol-containing liquid while flowing through the vapors. Methanol is fed in the region of the upper end of the tray fractionation column over the last catalytic bed, and the isobutene-containing hydrocarbon feed is fed at a point where at least two catalyst bed trays are above and at least one catalyst bed tray is below. . The process according to the invention is carried out at a pressure of from 0.5 to 10 bar and the obtained pure methyl tert-butyl ether is removed from the bottom of the column.

In a preferred embodiment of the process, methanol is fed above

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the last catalytic bed between 4 and 8 floors below the reflux point.

An advantage of the process according to the invention is, in particular, that the methyl tert-butyl ether formation reaction takes place in the liquid phase, so that no by-products are formed. A simple device can be used for the process according to the invention, i. a column with fractional trays, while at the same time allowing easy handling of the catalyst. The process according to the invention yields a pure product in high yield.

In practice, the C4 isobutene-containing hydrocarbon feed is fed to a tray fractionation column in which some trays are equipped with catalytic beds filled with sulfonated styrendivinylbenzene resins suitable for the production of methyl tert-butyl ether and these trays are separated from the other by either a few fraction trays, or one fraction tray. Methanol is fed to the top of the column, and preferably above the last catalytic bed and between 4 and 8 floors below the reflux point. The reaction of isobutene with methanol takes place on trays equipped with catalytic beds which are immersed in a methanol-containing liquid and through which vapors are bubbled. Separation of the methyl tert-butyl ether produced from the other constituents takes place on both the fractionated and catalytic bed trays to give the product at the bottom of the column, which is substantially pure methyl tert-butyl ether, and the overhead product C4 hydrocarbons except isobutene and methanol in an amount corresponding to the azeotropic mixture.

The isobutene-containing hydrocarbon feed is fed to a tray column of the present invention at a location where at least two trays containing the catalytic bed are above said feed and at least one tray containing the catalyst bed is below said feed. The vapors produced in the fractionation column in the bottom digester are bubbled through the catalytic beds, preferably at least three, with methanol and isobutene reacting under these conditions on the trays in the liquid phase which floods each catalytic bed.

The catalyst is in the form of spheres, as mentioned above, with a diameter ranging from 0.5 to 1 millimeter, and the thickness of each catalyst bed is up to 1 meter.

The liquid present on each catalyst-containing tray flows to the lower distillation tray by means of one or more overflows constructed in a conventional manner, the catalyst always remaining immersed in the liquid.

The catalyst is retained on each floor as it is held by the mesh at least on the lower and upper sides of the bed, which prevents the catalyst from being dispersed.

The process of the present invention will be illustrated in more detail with reference to the accompanying drawing, which is not intended to limit the scope of the invention in any way. In this drawing, a column with fractional trays is shown; with a fractionation tray 1 and a fractionation tray 2, on which fractionation tray 2 is provided a catalytic bed 3, which is provided with a mesh 4 and a mesh 5.

The liquid flows in the manner indicated by the arrows 6, passing through the catalytic bed 3. The vapor flows upward as shown by the arrow 7.

The process according to the invention will be illustrated in more detail by means of the following non-limiting examples.

He did

The process was carried out in a distillation column using flanged tube sections of 10 centimeters in diameter and 100 centimeters in length containing six cap trays (two caps on each floor). The column was assembled such that one-meter tube sections packed with catalyst were assembled with sections containing six trays, with six sections above the injection site and two sections placed under the feed. A C4 hydrocarbon fraction containing 50 percent isobutene at 2 kg / h was fed to the column.

The reflux ratio was 1: 1, with 575 grams of methanol being fed together with the reflux. The operating pressure was 800 kPa and the operating temperature ranged from 60 to 150 ° C. The overhead product contained 1035 grams of C4 fraction containing 30 grams of methanol and 5 grams of isobutene.

1540 g of practically pure methyl tert-butyl ether were obtained from the bottom.

Example 2

In this procedure, a distillation column was used, consisting of flange sections of 10 centimeters in diameter and 1 meter in length, each incorporating 6 distillation trays (capillary distillation trays). Each distillation tray contained two bubbling caps.

The column was assembled by alternately placing one-meter sections filled with catalyst and six-storey sections, with a total of 6 inserts (s) positioned above the feed point of the feed and 2 sections below the feed point of the hydrocarbon feed.

A C4 hydrocarbon feed containing 50% isobutane was fed to the column.

The reflux ratio was maintained

1: 1, with 570 grams of methanol being fed with reflux. The pressure at this point was 500 kPa and the temperature was maintained between 40 and 130 ° C. . By the procedure of this example, the following was obtained: - a product from the top of the column in the form of C4 hydrocarbons in an amount of 1045 grams containing