DE843456C - Process for the production of high-aromatic, highly knock-resistant gasolines from aromatic-rich, difficult to split middle oils - Google Patents

Description

Process for the production of aromatic-rich, highly knock-resistant petrol from aromatic-rich, difficult-to-split middle oils The processing of aromatic-rich, difficult-to-split middle oils, such as fractions from coal tar, smoldering tar from lignite or bituminous coal or sump phase oil from the pressure hydrogenation of carbons or tars, to petrol in one operation by splitting pressure hydrogenation has so far in most cases only at very high hydrogen pressures, z. B. 700 at, can be carried out. When these middle oils are rich in oxygen, nitrogen and sulfur compounds, olefins and aromatics, finite condensed benzene rings, the catalyst decays rapidly at lower pressures. It has therefore also been proposed to hydrogenate the middle oils first over strong hydrogenation catalysts at temperatures around 400 ° and high hydrogen pressures so that as few lower-boiling or gaseous hydrocarbons as possible are formed, but oxygen, nitrogen, sulfur compounds and olefins are split or hydrogenated . According to the previously known procedures, however, the aromatic hydrocarbons are also hydrogenated to the corresponding naphthenes. The middle oil obtained can be converted into gasoline easily and in good yield by cracking pressure hydrogenation, but this consists predominantly of paraffinic and naphthenic hydrocarbons. In terms of its engine-related properties (knocking behavior), it therefore does not meet the requirements that must be made of so-called high-performance aviation fuel.

It has now been found that when using the highest possible temperatures in the hydrogenation stage, namely those from 48o to 55o °, preferably up to 52o °, and at pressures from 100 to 700 at, preferably from 100 to 300 at, and a hydrogen partial pressure of over 5o at over catalysts, which have a relatively low cleavage and have a hydrogenating effect, contain aromatic middle oils from which oxygen, Nitrogen and sulfur compounds as well as the olefins have disappeared and the Surprisingly, in a subsequent stage under the conditions of the cleavage Let pressure hydrogenation convert directly into aromatic-rich gasoline.

The catalysts required to carry out the first stage consist of oxides or sulfides of the metals of the 2nd to B group of the periodic Systems, preferably of the 5th and 6th group, which are expedient only in amounts up to about 30% on low-splitting carriers, e.g. B. active clay, silica gel or activated carbon, are applied; Carrier such. B. man-made silicates are therefore unsuitable for this. Under these conditions in the hydrogenation stage only the aromatics with condensed benzene rings, e.g. B. naphthalene derivatives, hydrogenated, and mostly only partially so that z. B. naphthalene in tetrahydronaphthalene is convicted. Hydrocarbons with uncondensed benzene rings remain largely unchanged, or it is only due to the splitting off of alkyl groups their boiling points lowered, so that the aromatic content on the whole almost unchanged remain. The procedure for the first hydrogenation stage also differs from the previously known in that the conditions are chosen so sharply, that a certain formation of gas and gasoline cannot be avoided, but it is allowed to do so this by appropriate choice of the throughput expediently not more than 30 percent by weight of the starting material increase.

The gasoline formed in this stage already has a high aromatic content, about 50 percent by volume. In the case of catalysts, as they are for the previously known modes of operation were used for pre-hydrogenation, temperatures of over 480 ° at high Hydrogen pressure should be avoided in any case, as under such conditions a too strong splitting of the middle oil took place. When the invention is based On the other hand, working at such a high temperature is already used to maintain effectiveness of the catalytic converter is absolutely necessary. Used as a catalytically active substance and If a? @zetal oxide is selected as the carrier, then when the catalyst subsides the old activity by burning off the deposits formed on the catalyst can be restored with oxygen-containing gases.

The second stage, the transfer of what was produced in the first stage medium oil rich in aromatic compounds into a highly aromatic gasoline, must be steered in such a way that that in the cleavage only the unsaturated compounds formed, on the other hand not the benzene rings are hydrogenated. This is achieved by means of particularly suitable catalysts achieved. These are obtained by using catalysts with a high splitting effect, namely artificially produced aluminum and / or magnesium silicates, small amounts, d. H. about 0.1 to 5 0/0, of an oxide or sulfide of a metal of the 2nd to B Group of the Periodic Table. When using such catalysts it is then not only no longer necessary, but even inexpedient, when it is pressed to work above about 3oo at. At temperatures from 35o to 500 °, preferably 400 to 44o °, and hydrogen pressures of 40 to 300 atmospheres, preferably 100 to zoo at, one gets a gasoline with 50 to 20 percent volume from the middle oil of the first stage Aromatics.

The aromatics-rich gasoline produced in the first stage (pre-hydrogenation) has the properties of particularly high-quality aviation gasoline, so-called high-performance gasoline. However, especially with regard to its engine properties, as expressed in the overcharge curve, it is still exceeded by the gasoline produced in the second stage. The excellent engine properties of gasoline are due to the high aromatic content and the high degree of branching of the paraffinic hydrocarbons. A mixture of the gasoline of the first and second stage usually has better properties than are necessary for a high-performance aviation gasoline and can therefore be used with gasoline of lower value, e.g. B. straight-run gasoline from petroleum, are blended. As a result of the high aromatic content, pure aromatic hydrocarbons, especially toluene, which is extremely important for explosive purposes, can also be obtained from the gasoline obtained. Example A middle oil boiling in the boiling range from 170 to 31o ° from a coal tar with a high naphthalene content is passed with hydrogen-containing gas at zoo at pressure and 500 ° over a catalyst made from active alumina with 10% molybdenum oxide. The throughput is ikg0l jeLiterKatalysator and hour and the amount of hydrogen-containing gas 5ooo 1 per kilogram and 01 hour. A-Ian receives 3.3% gaseous hydrocarbons, 18.7% gasoline, and 78% medium oil.

The gasoline and the odor oil have the following key figures gasoline: d .. = 0.725, bromine number i, aromatic content 50 percent by volume, octane number (MM) 82, boiling range 60 to 165 °, boiling 29 percent by volume to 100 °. Middle oil: dzo = 0.943, bromine number 1.5, aromatic gelialt co percent by volume, boiling range 170 to 29o °.

The middle oil obtained in this stage is further treated at 42o ° and zoo at over an artificial aluminum silicate with a particularly high splitting effect, which contains 1% molybdenum oxide. The throughput is o, 9'kg oil per liter of catalyst and hour, the '\ lenge of the hydrogen-containing gas 5ooo l per kilogram and 01 hour. The gasoline present in the reaction product (45%) is distilled off and the middle oil is returned to the same stage. In this way, all of the middle oil can be converted into gasoline and gaseous hydrocarbons. From 100 parts by weight of medium oil, 82 parts by weight of gasoline and 18 parts by weight of gas, mainly propane and butane, are produced. Gasoline is characterized by the following properties: dz, = 0.795, bromine number 0.8, aromatic content 58 percent by volume, octane number (JIM) 81, boiling range 50 to 65 °, boiling 57 percent by volume to 100 °.

Claims (2)

PATENT CLAIMS: i. Process for the production of aromatic rich, particularly knock-proof petrol from aromatic-rich, difficult-to-break medium oils, characterized in that the middle oils are first used over oxides or sulfides of the metals of the 2nd to B groups of the Periodic Table, which are on carriers with lower Splitting effect, e.g. B. aluminum oxide, silica gel, activated carbon, are applied at Temperatures from 48o to 55o °, pressures from 100 to 700 atm and a hydrogen partial pressure of over 5o at while maintaining the aromatic content of oxygen, sulfur and Nitrogen compounds and unsaturated components freed the resulting gasoline separates and the hydrocarbons boiling above the gasoline boiling range over high artificially produced aluminum and / or magnesium silicates with a splitting effect, the small amounts of oxides or sulfides of the metals of the 2nd to B group of Periodic table included, at temperatures from 35o to 5oo ° and pressures of 40 to 3oo at converted into aromatics-rich gasoline. 2. The method according to claim i, characterized in that the gasolines obtained in the two stages with one another or can be combined with other less knock-resistant gasoline.