CS232749B2 - Method of methyl tertiary butylether production - Google Patents

Description

A process for preparing methyl tert-butyl ether by reacting isobutylene contained in a hydrocarbon feedstock which also contains butadiene in a concentration ranging from 10 to 70 percent by weight. with methanol in at least one ion-exchange resin catalyst reactor, wherein more are used. The reactors are connected in series at a temperature in the reactor or reactors in the range of from 50 to 60 ° C, preferably from 50 to 55 ° C, characterized in that the reactants and the reaction products are allowed to flow through the reactor or reactors downward at a linear rate at a range of 0.5 to 2 cm / sec.

Methyl tert-butyl ether finds use in practice as a solvent, an extraction agent and as an intermediate for the synthesis of numerous other products.

The present invention relates to a process for the preparation of tert-butyl alkyl ethers in the presence of butadiene.

The addition of alcohols to tertiary olefins, such as lsobutene, to form tert-butyl alkyl ethers is an exothermic reaction which is catalyzed by acids. .

In the presence of suitable catalysts, such as macroporous ion exchange resin, a reaction takes place to equilibrate for a period that is interesting from an industrial viewpoint, even at relatively low temperatures (40 to 50 ^Q C).

It is known that it is not necessary to use highly pure isobutene for production, but any isobutene-containing fraction is suitable for this purpose, since the addition of the alcohol takes place selectively on the double bonds starting from the tertiary carbon atom. Particularly suitable starting materials are the catalytic cracking fraction and the steam cracking fraction, the latter being used either before or after the butadiene extraction.

When the C 1 fraction from catalytic cracking or steam cracking after butadiene extraction is used as the olefinic feedstock, methanol or ethanol is used as alcohol and amberlyst 15 or Levvatit SPC 108 sulfonated macroporous resin is used as catalyst, the reaction can be used industrially over a wide range reactor types and operating conditions aimed at optimizing the conversion of one or the other reactant. In these cases, high selectivity is always achieved along with good catalyst performance, whether this performance is characterized by catalytic activity or catalyst life.

When a high butadiene content olefinic fraction is used as the starting batch, such as the C 6 steam cracking fraction which has not been subjected to butadiene extraction, mu. In particular, it is necessary to maintain a strict relationship between temperature and space velocity as described in U.S. Patent 4,039,590.

However, it has been found that when the isobutene etherification is carried out in the presence of butadiene in a tubular reactor containing macroporous resin and the reactants are fed into the reactor in a normally top-down manner, pressure loss increases over time, even when operating under conditions allowing high butadiene recovery (99% or greater) and there is a slight decrease in conversion.

In the same test, which was carried out using a butadiene-free fraction, there was no increase in pressure loss or conversion. Surprisingly, it has been found that when the feedstocks containing tyutadlene are introduced into the reactor so that they flow from the bottom upward under conditions of slight expansion of the bed, the pressure drop δ as a function of time remains constant. The invention is based on this finding.

SUMMARY OF THE INVENTION The present invention provides a process for the preparation of methyl tert-butyl ether by reacting isobufylene contained in a hydrocarbon feedstock also containing butadiene at a concentration ranging from 10 to 70% by weight with methanol in at least one ion exchange resin catalyst reactor. of more than one reactor, these reactors are connected in series, at a temperature in the reactor or reactors in the range of from 50 to 60 ° C, preferably from 50 to 55 ° C, which is carried out by allowing the reactants and reaction products to flow reactor or reactors downwardly at a linear velocity in the range of 0.5 to 2 cm / s. Acidic macroporous ion exchange resins are used as catalysts in the process of the invention.

In particular, methyl tert-butyl ether is used as a solvent, it also serves as an extraction agent and can also be used as an intermediate in numerous organic syntheses.

The following examples serve to illustrate the invention in greater detail. The examples are only illustrative and do not limit the scope of the invention in any way.

Example 1

The fraction of the following composition

Substance Content (° / o weight) propylene 0.46 isobutane 6.87 n-butane 11.80 1-butene 11.39 isobutylene 30.19 2 + -but 3.25 cis-2-butene 1.55 butadiene 34.43

The mixture is mixed with methanol in an amount such that the isobutylene / methanol molar ratio is 0.85 and the mixture is passed at a throughput of 14 l / h and a temperature of 50 ° C by two reactors connected to. series having a total volume of 4.5 liters and filled with 4 liters of catalyst. The catalyst used is a macroporous resin having sulfone exchange groups with a capacity of 4.6 meq. H ⁺ / g dry matter. The reactants flow in a bottom-up direction at a linear velocity of 1 cm / s.

The following conversion values and pressure losses versus time are ascertained:

Time (h) 24 500 2000 Pressure loss in reactor 1 (kPa) 20 May 20 May 20 May Pressure drop in 2nd reactor (kPa) 20 May 20 May 20 May Content of methyl tert-butyl ether (% by weight) 38.1 38 38 Dimer and codimer content (° / o by weight) 0.05 0.05 0.05 Butenylether content (% / weight) 0.2 0.15 0.2 Isobutene conversion 96.6 96.4 96.4 Regeneration of butadiene > 99 > 99 - 99

Example 2 (comparative example)

The batch described in Example 1 above is introduced into two reactors connected to each other in series at the same temperature and at the same space velocity, but

Time (h)

Pressure loss in reactor 1 (kPa)

Pressure loss in the 2nd reactor (kPa) Content of methyl tert-butyl ether (% by weight) Content of dimers and codimers (% by weight) Content of butenylethers (° / by weight) Conversion of isobutene

Regeneration of butadiene

Example 3 (comparative example)

To the olefinic fraction containing 35% by weight of isobutene and 0.2% by weight of butadiene is added methanol in such a way that the direction of flow of the reactants is from top to bottom.

At the beginning of the test, analogous results to those described in Example 1 were obtained, but with continued time, a gradual increase in pressure drop and a slight decrease in conversion were observed.

in

500 2000

30 40 150 30 50 180 38 37.9 36 0.1 0.1 0.05 0.2 0.2 0.2 96.4 96.1 91.3 > 99 > 99 > 99

An amount such that the molar ratio of isobutene to methanol is 0.85.

At 14 l / h and 50 ° C, the mixture is passed through two reactors connected in series, with the flow direction being from top to bottom. In the absence of butadiene, no increase in pressure drop or decrease in conversion over time is observed.

Time (h) 24 500 2000 Pressure loss in reactor 1 (kPa) 30 30 30 Pressure drop in 2nd reactor (kPa) 30 30 30 Content of methyl tert-butyl ether (% by weight) 43.1 42.9 43 Dimer and codimer content (° / o by weight) 0.3 0.3 0.2 Isobutene conversion 96.8 96.6 96.6

Claims (1)

OBJECT OF THE INVENTION A process for preparing methyl tert-butyl ether by reacting isobutylene contained in a hydrocarbon feedstock which also contains butadiene in a concentration ranging from 10 to -70% by weight with methanol in at least one ion-exchange resin catalyst reactor, when more than one is used. reactor, the reactors are connected in series, at a temperature in the reactor or reactors in the range of from 50 to 60 ° C, preferably from 50 to 55 ° C, characterized in that the reactants and reaction products - are allowed to flow through the reactor or bottom-up reactors at a linear velocity in the range of 0.5 to 2 cm / sec.