DE1055731B - Process for the separation of straight-chain hydrocarbons - Google Patents

Description

Process for the separation of straight chain hydrocarbons Invention relates to the manufacture of hard and flexible waxes waxes recrystallized in one step from solvents, made from so-called bright-stock slack wax by single-stage recrystallization at temperatures in the range from -7 to 16 ° C have been won. Bright stock slack wax is made from the in the vacuum stage residues obtained from the distillation of crude petroleum and often referred to as raw microcrystalline wax because it contains large amounts of microcrystalline Contains wax with good flexibility and adhesiveness.

The aim of the invention is a method for producing flexible Good quality wax for coating and enrobing or for use as a modifying agent Component for increasing the flexibility of paraffin waxes and the production of hard waxes suitable for use as polishing waxes. Flexible waxes for coating and covering should not be sticky and firm to the touch, d. H. a melting point of over about 60 ° C and a depth of softening (penetration) at 25 ° C of no more than about 50 mm / 10 (Institute of Petroleum, Standard Test Method 50/4 $).

It has already been suggested mixtures of hydrocarbons by reaction with urea in the presence of urea non-dissolving solvents to undertake. In contrast, the invention relates to a method for separating straight chain hydrocarbons of a hydrocarbon raw material of such with non-straight chain using urea and formation of adducts from urea and straight-chain hydrocarbons at elevated temperatures, separation and decomposition of the adduct formed, which is characterized in that as The starting material is bright stock slack wax recrystallized in one step from solvents is used and the adduct formation is carried out in a wax solvent, in which urea is almost or completely insoluble and does not have a boiling point below 110 ° C, the adduct from the solution of the non-added wax component separated and heated in a fresh amount of the same wax solvent decomposed and then filtered off, whereupon the added (hard) and the non-added (flexible) wax content can be obtained from its solution.

According to the invention, the starting material is thus in a wax solvent, in which urea is not soluble, dissolved. Solid urea is added to this solution and agitates the mixture at elevated temperatures to form the adducts straight-chain hydrocarbons present in the starting material. Then that will The adduct is filtered off and the non-added (flexible) wax component from the filtrate obtained by distilling off the solvent, while the adduct leads to its decomposition heated in a fresh portion of the same solvent. This separates the solid urea is removed and the converted wax goes into solution in the solvent. Then the urea is filtered off from the solution and the added (hard) Wax recovered from the solution by distilling off the solvent while the separated urea is added to a new batch of starting material. Of the The term "insoluble" denotes a solubility of less than 1% at the reaction temperature.

The solid urea is preferably added to the wax solution in a weight ratio from 0.25 to 5.0 parts of urea per part of wax is added.

Since wax-urea adducts are not sufficiently decomposed at temperatures below 110 ° C., the boiling point of the solvent used should not be below this temperature in order to keep losses to a minimum. The following solvents are particularly suitable: a) xylene (in all commercially available forms), b) toluene, c) mixtures of 65 % xylene and 35% isohexyl alcohol, d) mixtures of 70% xylene and 30% isoamyl alcohol. None of these solvents cause effective decomposition of the adducts at 100 ° C, whereas with solvents a) and b) at temperatures of 110 ° C a 92% recovery of the reacted wax and at 115 ° C with solvent c) a 96% recovery - up to 97% and with d) a practically 100% recovery is achieved. Since the boiling point of toluene is 110 ° C, it is therefore less suitable than other solvents with a higher boiling point.

In the case of solvents a) and c), the reaction must be carried out by adding Traces of a previously prepared adduct are released; with the other solvents this is not necessary, although here, too, the reaction speed is reduced is accelerated. Example 1 Bright stock slack wax recrystallized in one stage from solvents Middle Eastern crude oil is made in a mixture of 30% isoamyl alcohol and 70% / a commercial xylene in a ratio of 10 ccm of solvent per 1 g of wax solved. Then solid urea is made in a weight ratio of 2 parts Urea added per part of wax. The mixture is then mixed with a dispersing stirrer stirred at 71 to 77 ° C and the reaction for different lengths of time carried out. Thereafter, the reaction mixture is sintered from stainless Steel filtered off, the adduct with fresh solvent at reaction temperature is washed. The wax that has not been added is removed by distilling off the solvent recovered from the filtrate.

The adduct is made by heating in a fresh amount of the same Solvent decomposes at 115 ° C, with the reacted wax in the solvent goes into solution and solid urea is separated. The urea is filtered off and used to treat fresh raw material. The added amount of wax is obtained by distilling off the solvent.

Yields and properties of the waxes obtained are shown in Table 1. Table 1 Response time in hours 1 @ 2``ZI4 @ 6 I. yield Added Wax content ...... 16.7 18.6 24.6 24.6 Not added Wax content ...... 83.3 81.4 75.4 75.4 Melting point in ° C Added wax. . 88 '88 87 - Not added Wax ........... 66 I 66 64 - Flexibility Cycles at 0 ° C Added wax. . <1 '<1 <1 - Not added Wax ........... 800; > 1000 1000 1000 The recovered added mache is in all cases practically 1000 /, of the added wax content.

Example 2. The procedure of Example 1 is followed, but a mixture of 35% isohexyl alcohol and 650 % commercial xylene is used as the solvent. In this case, the reaction must be initiated by adding traces of a previously prepared adduct.

Table 2 shows the yields and properties of the waxes obtained. Table 2 Response time in hours 1 2i; '2 4 I. yield Added wax content. . 21.3 I 20.7 I 24.0 Unadded wax ' share ................ 78.7 79.3 76.0 Melting point in ° C Added wax ...... 87.5 87 87 Unadded wax. 65.5 64.5 64.3 Flexibility cycles at 0 ° C Added wax ...... <1 <1 <1 Unadded wax. . 800 800 850 The recovered added wax is in all cases about 96 to 970 /, of the added wax content. Example 3 Bright stock slack wax from Middle Eastern crude oil recrystallized in one stage from solvents is dissolved in commercially available xylene in a ratio of 1: 5 cc of solvent per g of wax. Then solid urea is added in a ratio of 3 parts urea per part wax. The mixture is inoculated with traces of a previously prepared adduct and stirred with a dispersing stirrer at 52 to 54 ° C., ie about 3 ° C. above the solubility temperature. The reaction is carried out for different lengths of time. The reaction mixture is then filtered off through a stainless steel sinter and the adduct is washed with fresh xylene at the reaction temperature. The unadded wax is recovered from the filtrate by distilling off the solvent.

The decomposition of the adduct is achieved by heating in fresh xylene causes at 110 ° C, whereupon the added wax goes into solution in the solvent and the solid urea separates. The urea is filtered off and used for treatment used from fresh raw material. The added wax is made by distilling off of the solvent obtained.

Table 3 shows the yields and properties of the wax products. Table 3 Response time in hours 1 2'i2 4 yield Added wax content. . 11.7 14.0 26.8 Unadded wax share ................ 88.3 86.0 73.2 Melting point in ° C Added wax ...... 89 89 86 Unadded wax .. 70 I 69 64 Flexibility cycles at 0 ° C Added wax ...... <1 <1 <1 Unadded wax. . 320 I 590 1000 The recovered added wax is in each case about 92% of the added wax content.

An advantage of the process is that the same solvent can be used throughout the process and that upon decomposition of the adduct with the solvent, the added wax goes into solution in the solvent and so on the separated urea is available for the next batch. The problem large-scale recovery of urea from aqueous solutions is thus avoided.

The flexibility test is carried out on a machine on which a strip of wax broken by continuously bending it over a constant angle taking the flexibility out of that required to break the strip Number of cycles calculated.

Claims (7)

PATENT CLAIMS: 1. A process for the separation of straight-chain hydrocarbons of a hydrocarbon starting material from those with a non-straight chain using urea and formation of adducts from urea and straight-chain hydrocarbons at elevated temperatures, separation and decomposition of the adduct formed, characterized in that a single-stage starting material Bright stock slack wax recrystallized from solvents is used and the adduct formation is carried out in a wax solvent in which urea is almost or completely insoluble and which has a boiling point not below 110 ° C, the adduct is separated from the solution of the non-added wax component and combined by heating is decomposed and then filtered off, whereupon the added (hard) and the non-added (flexible) wax portion is recovered from its solution. 2. The method according to claim 1, characterized in that as a wax solvent xylene, mixtures of xylene and isohexyl alcohol and / or Mixtures of xylene and isoamyl alcohol can be used. 3. The method according to claims 1 and 2, characterized in that the solid urea to the wax solution in weight ratios from 0.25 to 5.0 parts of urea per part of wax is added. 4. Procedure according to Claims 1 to 3, characterized in that the reaction mixture during a Time of 1 to 6 hours, especially using a dispersing stirrer, is moved. 5. The method according to claims 1 to 4, characterized in that the elevated temperatures during the reaction in the range from 52 to 77 ° C. 6. Procedure according to claims 1 to 5, characterized in that the decomposition of the adducts is carried out at temperatures ranging from 110 to 115 ° C. 7. Procedure according to Claims 1 to 6, characterized in that the wax starting material in the Solvent dissolved in proportions of 5 to 10 cc of solvent per 1 g of wax will. Considered publications: German patent specifications No. 866 786, 869,070; Petroleum and Coal, 1956, pp. 237 to 241; Liebigs Annalen, 1949, 565, pp. 205/206.