DE945280C - Procedure for topping up hydrocarbon mixtures during storage - Google Patents

Description

Process for sweetening hydrocarbon mixtures during the Storage The process relates to the sweetening of hydrocarbon mixtures, in particular Gasoline that still contains small amounts of mercaptans while in storage.

Mercaptan-containing gasoline is usually subjected to a treatment, which eliminates or greatly reduces the mercaptan content of these gasolines. The latter is the case when the gasolines are treated extractive, often with one more very little residual mercaptan sulfur remains in the treated gasoline, the It produces a weakly positive doctoral test. It is generally difficult to get this Residual mercaptan content can be completely extracted with the production of doctor-sweet Gasoline, since then the extraction of the mercaptans becomes uneconomical, so that one is at Extractive mercaptan reduction with a very low residual mercaptan content content, which then, however, no doctor-sweet gasoline is obtained.

This residual content of mercaptan sulfur (hereinafter referred to as MS) in certain gasolines, e.g. B. Cracked gasoline, which is a mercaptan extraction means aqueous alkaline solutions (which often contain solubilizing additives such as i-butyric acid, naphthenic acids, Ethanolamines or may contain alkylphenols) were subject, can be made to disappear by so-called »sweetening«, something by storage takes place with exposure to atmospheric oxygen.

It is known that this sweetening is facilitated by adding of small amounts of resin inhibitors, one of which is di-sec-butyl-p-phenylenediamine represents the most suitable representative. However, such resin inhibitors are pind relatively expensive, and because they are very unstable to oxidation and when touched discolor with oxygen, the benzines mixed with resin inhibitors become Dark sweetness.

It has now been found that gasolines with low residual amounts of mercaptan sulfur when stored in the presence of oxygen, it is quickly sweetened, the gasoline being doctor-sweet if you add very small amounts of tetrahydronaphthalene to these fuels, without discoloration of the gasoline.

A gasoline mixture made up of top-grade gasoline and cracked gasoline and those hydrogenation gasolines obtained from the hydrogenation of petroleum residues and cracking residues arise both in the sump phase and in the gas phase, contains z. B. still o, ooo22 percent by weight of mercaptan sulfur and has a weakly positive doctoral test, the one without an addition, the. the sweetening effects or facilitates over sun days remains in the case of a storage ring with access to air.

The table below shows that after adding 0.02 to 0.005 percent by volume of tetrahydronaphthalene, sweetening takes place in a few days. Under the relevant test numbers, mixtures of the above four gasoline components were used, all of which had an MS content of 0.022 percent by weight and a weakly positive doctoral test and did not sweeten without additives. The petrol mixtures contained about 0.05 percent tetraethyl lead. Gasoline mixture, sweetened after - days Volume percentage addition of tetrahydronaphthalene 0.005 0.004 0.003 0.002 0.00 0 Original I - II > 80- 2 6 9 9 9 - 3 3 - - 3 - 4 3 - - 4 - 9 13 - -> z6 - xo * 3 - - - - - 1z 7 - - 13 z2 * 4 * Attempt io = attempt 9 + bare + rusty iron nail; * Experiment r2 = experiment ii + bare + rusty iron nail - @ - Cu and brass wire. For experiments 9 to = 2, the doctor's test is slightly more positive than that of experiments 2 to 4, which are identical to one another, but the MS content is the same in all experiments.

The io attempt is the same as for 9, only the petrol was used for Try one bare and one rusty iron nail added. It turns out that sweetening under the influence of metallic iron or iron oxides (rust) of z3 Days is shortened to 3 days, under conditions like those in normal iron Storage tanks are available.

During the sweetening, the addition of tetrahydronaphthalene does not change the resin content of the sweetened gasoline in a significantly unfavorable way, as the following table shows, which the glass cup tests of Experiment 2 show. In addition, the glass cup test of the sweetened gasoline was determined after it had been subjected to artificial aging for 4 hours under 7 atmospheric pressure at zoo ° C. Glass cup test, mg resin zoo cm 'gasoline Try artificial aging before after Original, without tetrahydro- naphthalene ................ 0.4 1.3 z + o, oo5 percent by volume tetra- hydronaphthalene ........... o.6 2.0 2 -f- 0.004 percent by volume Tetra- hydronaphthalene. . . . . . . . . ... . 0.8 1.3 2 -f- 0.003 percent by volume Tetra- hydronaphthalene. . . . . . . . . . . . 0.7 1.7 2 -E- o, oo2 percent by volume Tetra- hydronaphthalene. . . . . . . . . . . . 0.4 2.3 In the case of artificial aging, the pressure drop after reaching the reaction temperature of roo ° was such. slightly that there was an induction time of over 240 minutes, which represents a good storage stability of the gasoline sweetened by the addition of tetrahydronaphthalene.

The sweetening can also be done in the presence of octane-enhancing additives, such as lead tetraethyl or others.

It should also be mentioned that the sweetener with the addition of tetrahydronaphthalene The time required can be further shortened if the sweetening is done in daylight and / or the presence of aqueous alkali lye takes place, i.e. under conditions which are not the case with normal storage of gasoline with access to air, however can be met if necessary.

The gasoline that is supposed to sweeten can be very small Get the amount of air or oxygen mixed in shortly before storage; for the most In some cases, however, it is sufficient if the gasoline is not loaded with air in one Tank that breathes against air, which keeps the required amount of air in Gasoline is dissolved.

Is there a gasoline mixture to be sweetened, of which at least one component is present was subjected to a hydrating treatment, then the sweetening of a The addition of tetrahydronaphthalene which causes a gasoline mixture is replaced by an additive from naphthalene to the component that undergoes a hydrotreatment, provided the latter such is designed that this is tetrahydronaphthalene arises and this in the aftertreatment measures - such as distillation - in the Gasoline fraction remains.

Claims (6)

PATENT CLAIMS: i. Process for the production of doctor-sweet hydrocarbon mixtures, especially gasoline, from mixtures that contain mercaptan sulfur and have a positive doctoral test, by storing in contact with oxygen or gas mixtures containing these, especially air, with the addition of small amounts of tetrahydronaphthalene. 2. The method according to claim i, characterized in that 0.0005 to 5 percent by volume, preferably o, ooi to oi percent by volume of tetrahydronaphthalene is admixed. 3. The method according to claim i and 2, characterized in that in the presence of heavy metals such as iron, copper or lead, and / or their oxides sweetening he follows. 4. The method according to claim i to 3, characterized in that the sweetening takes place in the presence of octane number-improving additives such as tetraethyl lead. 5. Process according to Claims 1 to 4, characterized in that the sweetening takes place under the action of light and / or in the presence of aqueous alkaline solutions. 6. The method according to claim i for the production of doctor-positive gasoline when stored under air contact, characterized in that the gasoline contains a portion of gasoline or is admixed, which is formed by the hydrogenation treatment of hydrocarbon mixtures with the addition of naphthalene, wherein tetrahydronaphthahn is generated, which in the to sweetening gasoline mixture remains. Attached publications USA.-Patent No. 2 031 977, -