DE1190127B - Process for the selective hydrogenation of pyrolysis gasoline or its fractions - Google Patents

Description

Process for the selective hydrogenation of pyrolysis gasoline or its Fractions In the heat splitting (pyrolysis) of mineral oils above 600 ° C, mainly of crude oils and their fractions or residues, in particular fractions in the Gasoline boiling range, a pyrolysis gasoline is obtained in addition to gaseous fission products, which contains resinifying constituents (e.g. diolefins). It's not as fuel suitable as it leads to gumming in the engine. It is therefore necessary to use the resinous To remove constituents (e.g. diolefins), the ones that are favorable for the knocking behavior Monoolefins should be preserved. The pyrolysis gasoline also contains aromatics, which can be completely or partially isolated. To obtain these aromatics you have to Remove not only the diolefins but also the monoolefins from the gasoline. This is done by two-stage selective hydrogenation, with the highly resinous first Components - the diolefins - are hydrogenated and, in the second stage, at higher temperatures and mostly also under higher pressures, the monoolefins are hydrogenated with preservation of aromatics. You can also only use the aromatic-containing fractions in this two-stage process Apply hydrogenation.

It has now been found that pyrolysis gasoline or its fractions selectively in the trickle phase at below 100 ° C in the presence of noble metal catalysts Can hydrogenate selectively on supports if noble metal catalysts are used, which are applied to supports with an internal surface area of 50 to 100 m2 / g have, in which when applying the precious metal components to the carrier in the absence of alkaline substances has been worked, and that the so obtained Supported catalysts with sulfidic agents and then treated with hydrogen have been.

The diolefins are expediently removed from the pyrolysis gasoline in liquid form Phase, e.g. B. in the trickle phase. The raw materials trickle vertically Pipes over fixed catalysts in the reaction chamber in a static hydrogen atmosphere down. The temperature is between 20 and 100 ° C, advantageously below 75 ° C. It is useful for keeping the first quarter of the catalyst space or more below 50 ° C and only then to let the temperature rise, e.g. B. up to the mentioned maximum temperatures. It is generally worked at elevated pressures, for example between 20 and 100 atm., Advantageously between 30 and 60 atm.

The hydrogenation gas should contain at least 60 percent by volume hydrogen. As catalysts for the selective hydrogenation of pyrolysis gasoline or its fractions noble metal catalysts known per se are suitable, primarily 0.5 to 5 percent by weight Containing platinum and palladium on carriers with grain sizes of 2 to 10 mm, advantageously 3 to 6 mm, can be applied in the form of pills, sausages, balls. Synthetic or naturally occurring aluminum oxides are suitable as carriers, Silicas and silicates. Impurities such as iron oxide, magnesium oxide, titanium oxide, in naturally occurring compounds are often for the suitability of the wearer advantageous. The carrier should have an inner surface - determined by the BET method - Have from 50 to 100 m2 / g, advantageously 55 to 80 m2 / g. In the range 50 to 100 m2 / g is the mean pore radius for aluminum oxide substrates, for example about 50 to 150 Å. In the case of starting materials with a larger internal surface, one can set the desired range through controlled sintering, for example at 1000 to 1200 ° C and residence times of 2 to 20 hours. The mentioned area of inner surface has been used for the selective hydrogenation of diolefins in pyrolysis gasoline and its political groups have proven useful. For catalyst carriers with lower Surface, for example 10 m2 / g, you have to use more precious metal in the catalyst, in order to achieve similar hydrogenation effects as when using carriers in the above Surface area. You can use the supported catalysts of the invention higher Achieve throughputs than with those with a smaller surface. In the case of the hydrating Removal of diolefins from pyrolysis gasoline fractions for the purpose of subsequent Hydrogenation of the monoolefins at elevated temperatures is obtained when using the Catalysts according to the invention a hydrogenation product, which is in the heating for the hydrogenation the second stage proves to be more stable than when using it of substrates with a surface area smaller than 50 m2 / g. This better stability is important to avoid incrustations in the heating to the second hydrogenation stage. The supports of the present invention are found to be more useful than lower surface area supports. Is used for the removal of diolefins from pyrolysis gasoline carrier with Surface areas of more than 100 m2 / g, as often used for hydrogenation processes such catalysts deliver at the beginning, namely at around 200 m2 / g also good results, but their effect soon diminishes, so that the hydrogenation soon becomes unsatisfactory. The range between 50 and 100 M2 / g is accordingly particularly advantageous for the selective hydrogenation of diolefinic pyrolysis gasoline.

In making a suitable catalyst, aych is the form of the noble metal, especially the palladium on the carrier, is important. It has shown that when applying the noble metals to the carrier free alkali or alkaline reactive aqueous solutions must be absent. Only come neutral or sour Alkali salts in contact with the catalyst result in particularly effective catalysts. Alkali in the catalyst causes the catalyst activity to decrease.

You have to use the precious metals or precious metal compounds after application treat the carrier with sulfidic agents and then with hydrogen. The sulphurisation can be carried out with hydrogen sulphide or gases containing hydrogen sulphide take place like this: The carrier is soaked in an aqueous solution of a noble metal salt (e.g. sodium palladium chloride) and dries at 120 ° C. The dried catalyst is then sulphurized at normal or elevated temperature, washed chlorine-free and dried again at 150 ° C. Then it is at 100 to 250 ° C with hydrogen, optionally under pressure, treated until no more hydrogen sulfide escapes. The sulfurization can also be carried out with an aqueous hydrogen sulfide solution. Such catalysts lead to constant hydrogenation results. The hydrogenation effect is better than catalysts with precipitated noble metal, for example with Hydrazine as a reducing agent, without further treatment. The selectivity of the Catalysts according to the invention with regard to the preservation of the aromatics is more favorable than with catalysts with precipitated precious metal.

By using carriers with 50 to 100 m '/ g, the absence alkaline solutions and sulphurisation with subsequent hydrogen treatment one obtains catalysts particularly suitable for selective hydrogenating refining pyrolysis petrol containing diolefin or their fractions. Example l The one claimed for The catalyst required for the procedure was prepared in the following manner: On sausages (4 mm diameter and length) made of aluminum oxide (inner surface 65 m2 / g, medium Pore radius 135A) was 10 /, sodium palladium chloride, calculated on the catalyst, upset. The impregnated catalyst was dried at 120.degree. C., exhaustively at 70.degree Treated with hydrogen sulfide, washed free of chlorine and dried again at 150 ° C. It was then treated with hydrogen at 200 ° C until no hydrogen sulfide more escaped.

This catalyst was placed in a vertical tube 40 mm in diameter and 3 m in length. Gasoline from the pyrolysis of petroleum spirit at 750 ° C in the presence of steam (bp 40 to 120 ° C), from which the portions boiling below 35 ° C had been distilled off, was further distilled to a fraction with an end point of 195 ° C (Gum before aging 2 mg / 100 cm3). The hydrogenation pressure was 30 atmospheres. The gasoline was added to the top of the reactor (5 kg per liter of catalyst per hour) and trickled down over the catalyst in the hydrogen atmosphere. The gasoline inlet temperature was 30.degree. C., the outlet temperature 75.degree. After leaving the reactor, the gasoline was cooled to 30 ° C., collected in a separator located below the reactor and separated from the gas. 201 gas per kilogram of gasoline were released from the separator. The feed and hydrogenation product compare as follows: Key figure use of hydrogenation product 1 Color .................. yellow colorless Odor ................ non-aromatic pleasantly pleasant specific weight at 20 ° C ... . . . . . . . . . . 0.7990 0.7925 Bromine number (g Br / 100 g) ... 65.4 46.9 Diene content (Weight percent) ..... 15.1 1.14 Gum from aging (mg / 100 cm3). . . . . . . . . 2 2 Gum after aging (mg / 100 cm3). . . . . . . . . 3640 3 Induction time (minutes) 235 480 Octane number RON. . . . . . . . . without added lead ....... 99.7 98.7 with 0.04 ° / o TEL ....... 101.5 102 Example 2 The same catalyst as that from Example 1, but with 1.8% palladium on the support, was used to treat the 70 to 120 ° C. fraction from the pyrolysis gasoline from Example 1. The hydrogenation conditions were the same as in Example 1 The feedstock and hydrogenation product compare as follows: Key figure use of hydrogenation product 1 specific weight at 20 ° C. . . .. .... . . . . 0.810 0.800 Bromine number (g Br / 100 g) ... 29 14.8 Diene content (Weight percent) .... 7.25 0.1 Benzene (weight percent) 29.5 29.2 Toluene ................. 30.8 31

Claims (1)

Process for the selective hydrogenation of pyrolysis gasoline or its fractions below 100 ° C in the presence of noble metal catalysts on carriers, thereby characterized in that one uses noble metal catalysts on supports, the one have an inner surface of 50 to 100 ma / g, where the precious metal components are applied work has been carried out on the carrier in the absence of alkaline substances is, and that the supported catalysts obtained in this way then with sulfidic Agents and then treated with hydrogen.