CH626266A5 - Process for the addition of alcohols or glycol to acetylenic compounds contained in hydrocarbon streams for removing alkyne impurities from the latter - Google Patents

Description

The present invention relates to a process of adding alcohol or glycol to acetylenic compounds contained in hydrocarbon streams, characterized in that an alcohol or glycol is added to said acetylenic compounds in the presence of an acidic exchange resin, whose acid groups are totally exchanged both with mercuric ions and with alkaline or alkaline earth metal ions.

More particularly, the present invention applies both to the purification of so polluted hydrocarbon streams, and to the exploitation of these acetylenic compounds to produce industrially interesting products.

The method as defined in claim 1 therefore makes possible:

1. The elimination from a hydrocarbon stream consisting of ethylene, propylene and butadiene from salts and in mixture with other saturated and / or unsaturated hydrocarbons of acetylene, propine, 1 butine, 2 butin, vinylacetylene and diacetylene of simultaneous production of vinyl ethers and / or gem-diethers of these same compounds.

2. The eminination from butadiene streams (alone or in mixture with other saturated and / or unsaturated hydrocarbons with the same number of carbon atoms) of propine, I butine,

2 butin, of vinylacetylene and / or diacetylene with simultaneous production of the vinyl ethers and / or the gem-diethers of these same compounds.

3. The elimination from propylene streams (alone or in mixture with other saturated or unsaturated hydrocarbons with the same number of carbon atoms) of propine with simultaneous production of vinyl ether and / or gem-dieter corresponding.

4. The elimination from ethylene streams (alone or in mixture with ethane) of acetylene with the simultaneous production of vinyl ether and / or gem-dieter corresponding.

It is known that in most uses the saturated, olefinic and in particular diene hydrocarbons must be free of alkynic and in particular acetylenic compounds; for example the content of these in the butadiene monomer must be <50 ppm and this because of their poisoning action of the polymerization catalysts.

A particular aspect of the process defined in claim 1 consists in selectively adding to said acetylenic compounds a particularly and preferably methanol alcohol, or a glycol particularly and preferably ethylene glycol in the presence of an acid ion exchange resin, whose centers have been totally exchanged with mercuric ions (H ~ ions) and with alkaline or alkaline earth metal ions (Men + ions).

The products that are formed are subsequently removed and recovered through simple and inexpensive rectification operations.

The exchange ionic resin to be used has an acidic character and preferably contains sulphonic groups (-S03H supported on resins, for example polystyrol, divinylbenzenic or polyphenolic), but resins containing -COOH groups, preferably supported on acrylic resins, can also be used.

In general, the ions of the metals indicated above can be added to the resin as salts of the same, for example as nitrate or mercury and sodium acetate, but hydroxides can also be used for this purpose (for example sodium can be added as hydroxide) ; the Hg ions content of the resin can also be higher than that of the Men + ions. It is preferable that the Me, 1 + ions and then the Hg ++ ions are added to the resin first; it is also preferable that during the operation aqueous solutions are used and that the resin, after the treatment, is dehydrated by washing with methanol or in general with the alcohol used in the reaction.

The hydrocarbon streams which can be treated in accordance with the present invention are paraffinic, olefinic and dienic (in particular streams rich in ethylene, propylene and butadiene).

The addition can be carried out in a wide range of temperatures and pressures; one operates advantageously between - 20 ° C and + 80 ° C and even more advantageously between 10 ° C and 50 ° C, at a pressure chosen so as to maintain the hydrocarbon streams at the reaction temperature in the liquid or gas phase game (depending on the opportunity to treat these in the vapor or liquid phase). Operating in the liquid phase, the space velocity (LHSV) of the reaction is between 0.1 and 100 (cc / h.gr). It is advisable to operate in the presence of a stoichiometric excess of alcohol or glycol with respect to acetylene products; in practice it is convenient to operate with a molar ratio (aIcol) / (total acetylenes) = 1.05 - 2.1 depending in particular on whether vinyl ethers or gem-diethers are desired.

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It is interesting to note that by operating with the process defined in claim 1, the resins exchanged totally with mercuric ions and with alkaline or alkaline-earth metal ions retain their activity for a period of time at least 3 times greater than that of the resin without alkaline metal ions. or alkaline-earthy. This is probably also due to the fact that with the resins treated in accordance with the process defined in claim 1, the secondary reactions that generally occur in the presence of acidic ion exchange resins play a less predominant role.

Some practical examples of carrying out the process as defined in claim 1 will now be provided.

Example 1

98 g of acid resin type Amberlyst 15 (containing acid groups type -SOsH) are treated with 2 liters of a 10% p aqueous solution of NaOH; it is kept under stirring for 1 h and then filtered and washed the resin with distilled water until a neutral reaction. The same resin is subsequently treated with 300 cc of an aqueous solution, acid for acetic acid, containing two g. Hg ++ ions (such as mercury acetate); it is kept under stirring for 24h then it is filtered under vacuum and washed repeatedly with anhydrous methanol.

Part of the resin thus treated is loaded into a 10 cc volume reactor, kept at 40 ° C by means of a thermostatic circuit. In the same are pumped continuously, operating at 10 athe. 50 cc./h of a C4 stream rich in buta-5 diene (= *. 55%) and containing 4300 ppm of vinylacetylene, ~ 1500 ppm of 1 butine, ~ 1000 ppm of propine and methanol in such an amount as to have the ratio total alcohol / acetylene = 2.1 moles / moles.

The content of all the three aforementioned acetylenic compounds io detected in the liquid samples taken at the exit of the reactor (every 5 h) is constantly <10 ppm in the whole period of time in which the test was carried out (120h).

Example 2

15 In the same reactor indicated in Example 1, operating at T = 30 ° C and at P ~ 20 ate, they are pumped at 50 cc / h of propylene containing 0.3% of propine and methanol in an amount such as to have the ratio alcohol / acetylene = 1.1 moles / moles.

20 The propine and 2.2 dimethoxypropane content detected in the liquid samples taken (every 5 h) at the exit of the reactor during the whole time in which the test was carried out (300 h) is respectively ~ 10 ppm and 0.78% by weight.

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Claims (11)

626266 1. Process of adding alcohol or glycol to acetylenic compounds contained in hydrocarbon streams, characterized in that an alcohol or glycol is added to said acetylenic compounds in the presence of an acidic exchange resin, whose acid groups are totally exchanged both with ions mercuric, either with alkaline or alkaline earth metal ions. 2. Process according to claim 1 wherein the acidic exchange resin contains sulfonic groups. 2 3. Process according to claim 2 wherein the sulfonic groups are supported on polystyrene resins, polyphenols, divinyl benzene or mixtures thereof. 4. Process according to claim 1 wherein the acidic exchange resin contains carboxyl groups. 5. Process according to claim 4 wherein the carboxylic groups are supported on acrylic resins. 6. Process according to claim 1 wherein the addition reaction is carried out in the gas phase. 7. Application of the process according to claim 1 for the removal of alkynic compounds from streams containing them. 8. Application according to claim 7, characterized in that acetylene, propine, 1-butine, 2-butine, vinylacetylene and diacetylene are eliminated by a hydrocarbon stream consisting of ethylene, propylene and butadiene alone or in mixture with other saturated and / or unsaturated hydrocarbons with the same number of carbon atoms and in which the vinyl esters and / or gemdiesters thus obtained are removed by rectification. 9. Application according to claim 7, characterized in that the acetylene is eliminated by a hydrocarbon stream consisting of ethylene, ethylene alone or in mixture with ethane and / or non-condensable gas and in which the vinylester and / or the gem-diester thus obtained is then removed by rectification. 10. Application according to claim 7, characterized in that propine is eliminated by a hydrocarbon stream consisting of propylene alone or in mixture with other saturated and / or unsaturated hydrocarbons with the same number of carbon atoms and in which vinyl ester and / or gem-diester thus obtained is then removed by rectification. 11. Application according to claim 7, characterized in that propine, 1-butine, 2-butine, vinyl-acetyl-lene and di-acetylene are eliminated by a hydrocarbon stream consisting of butadiene alone or mixed with other saturated and / or saturated hydrocarbons having the same number of carbon atoms and wherein the vinyl esters and / or gem diesters thus obtained are then removed by rectification.