DE1197872B - Process for the purification of C to C split wax or split raffinato olefins - Google Patents

Description

Process for cleaning C6 to C18 split wax or split raffinato olefins Technical olefins or olefin mixtures, such as Cß to Cls split wax or split raffinate olefins, contain impurities which are noticeable as polymerisation inhibitors make and therefore have to be removed from the olefins. Obviously exist these impurities also partly come from dienes, although their exact composition and constitution could not yet be clarified.

It is known per se that liquid hydrocarbons are purified by passing them through a stationary bed of granular absorbent, like clay, seeps through or percolates (cf. A. F a r k a 5> Physical Chemistry of Hydrocarbons ", (, Part II, p. 339). It is also known for the same Purpose to use a method in which columns with a relatively large ratio filled from length to diameter with silica gel as an absorbent, at which fractionation and separation of the hydrocarbons then takes place (cf. A. F a r k a s, loc. cit., p. 340).

However, this procedure is less suitable for implementation on an industrial scale, since the percolation as a result of the required column length is quite slow, while on the other hand the introduction and packing of the Absorbent material requires great attention and care.

Surprisingly, it has now been shown that these difficulties Can be remedied by cleaning Cis to C18 spakwax or split raffinate olefin carried out in such a way that silicon dioxide heated to at least 1000 C is used in these olefins, that has a surface area of at least 500 m2 / g, slurries and that the impurities separating silicon dioxide containing in the usual manner.

The process according to the invention is suitable for such olefins, the thermal or catalytic cleavage of a hydrocarbon feedstock, such as is obtained from the refining of crude petroleum. Such olefins are commonly referred to as split wax olefins. Others that can be used according to the invention Olefins are those that arise when a raffinate is cracked, which is used in the selective Obtained solvent extraction of heavy catalytically cracked cycle oils will. Since the relevant C6 to Cl8 fission olefins at normal temperatures and Printing are liquid, the process according to the invention can be used without further ado Perform normal pressure.

If the olefin mixture in question contains a large proportion of o; -olefins contains, it may be desirable to perform a urea extraction before the cleaning by slurrying with hot silica. This is particularly desirable when the olefin is to be subsequently polymerized, e.g. B. after the so-called Ziegler process.

Particularly good results are achieved by using silica gel achieved, which is in activated form, for example a commercially available one "Silica gel 90/120 mesh," which is available from Silica Gel Co. Ltd. manufactured as well as Davison's "923 Silica Gel" (100 to 200 ASTM) (US) mesh) and others Davison silica gels, such as grades 912, 922, 950, 963, 70 and 35.

In particular, it has been found that an average mesh size (B. S. S. Maschen) between about 70 and 150, for example between 90 and 120 Mesh, is most suitable. The SiO2 content of the silica or silica gel should preferably be at least 98 percent by weight.

Many of the aforementioned silica gels contain silica between 99.5 and 99.85, the impurities mainly being oxides of iron, Sodium, potassium, titanium, zirconium and often aluminum as well. The silicon dioxide, z. B. the silica gel, should have a large surface area that is at least 500 m2 / g and preferably at least about 650 m2 / g.

The silica should be used prior to mixing with the olefin mixtures to at least 100 "C and in particular to at least 150" C and even better to 200 "C or heated above. Heating to 200 "C for 24 hours can in some Cases be expedient. The temperature of the slurry depends on, for example the amount of silica and the mixing time, but preferably left the temperature of the sludge does not drop below 30 "C.

The temperature of the olefin or olefin mixtures in which the slurried hot silica or silica gel need not be particularly to be increased; it can be, for example, between 10 and 25 "C. Of course by mixing the olefin and silica, the temperature of the olefin becomes increased but if an excessive amount of silica is not used the temperature rise usually no more than about 15 "C.

The amount of silica or silica gel required varies depending on the level of impurities in the olefin as well as on the temperature and the mixing time. However, it has been found that especially when cleaning urea extracted olefin less than one third based on silica on the weight of the olefin, can be applied with success.

It is convenient to add the silica to the olefin at once and not add about continuously.

However, the process can be adapted to a continuous procedure be done by z. B.

Silica gel can trickle onto the continuously moving olefin.

When carrying out the process according to the invention, the mixing can be carried out of the olefin with the silica or silica gel to form a slurry by moving the mass, e.g. B. with a stirrer or preferably a so-called Vibromixer. Mixing should take at least about 10 minutes, and good results are obtained when the mixing time is about 30 minutes.

After the slurry has finished mixing, it can now be done in the essential purified olefin can be separated from the sludge. this can after different physical separation methods take place, e.g. B. by distillation, fractional Distillation, fractional distillation under reduced pressure, centrifugation or filtering. Centrifuging or filtering the sludge has proven to be special proved suitable.

The olefins, particularly olefins extracted with urea, which have been purified by the process according to the invention are particularly suitable for subsequent polymerisation according to the Ziegler process. On the other hand you can olefins purified by the process according to the invention for the production of synthetic olefins Detergents, e.g. B. of alkylbenzenesulfonates can be used.

Example A C8 split wax olefin fraction which was mixed with urea had been extracted, purified using silica gel, which through the silica Gel Co. Ltd. Marketed under the name »Silicagel 90-120 Messe will. A number of tests were carried out using different temperatures, different amounts of silica gel and different mixing times.

A large flask with a Thermometer and a vibromixer was equipped with a stainless steel plate Steel included to give the liquid phase a downward flow. That Olefin was charged in the flask and the temperature increased if desired adjusted before adding the silica gel. The mixture was then 10 or 30 minutes and stirred for 45 minutes in one attempt, after which it was turned on the pump by a highly porous, sintered glass funnel was vacuumed.

The product was tested by adding a few drops from TiCl4 to a dry sample of the olefin in a dry inert atmosphere.

If a precipitate formed, which indicated that the olefin was still Contained impurities, such as. B. Serves and allied compounds, became the Treatment repeated.

The reaction conditions and the results obtained for each experiment are given below. Weight silica gel Olefin Silica Gel Olefin Temperature Mixing Time Olefin Ratio olefin olefin average temperature (Weight- at the beginning maximum (volume- to (Parts by volume) parts ° C ° C minutes percent) silica gel ° C a 50 room temperature 34 10 90 150 400 b 50 room temperature 39 10 80 c 50 room temperature 38 10 68 1: 3 400 150 room temperature 55 10 76 1: 5 150 a 50 96 110 10 90 2: 2 150 400 # b 50 100 109 10 76 400 50 room temperature 34 30 88 5: 1 150 400 50 room temperature 30 45 88 5: 1 150 200 25 room temperature 35 30 83 4: 8 200 to 220 200 30 room temperature 34 30 85 4: 1 200 to 220 The effect of a slurry treatment on the results of subsequent polymerization experiments using triethylaluminum and TiCl4 as a catalyst and isooctane as a solvent under normal conditions is shown in the table below: Yield bromine number kinetic Starting material of polymer of the polymer viscosity Weight percent 380 (cit) Urea extract before slurrying .... 71 37 18.7 after slurrying ... 81 34 19.8 However, this polymerization process is not the subject of the protection request.

Comparative experiment For comparative purposes, two experiments were carried out at room temperature by means of percolation using the same starting material and the same absorbent as in the above slurry experiments. The diameter of the column was 1.8 cm. The further test conditions and results are given in the table below: Silica gel Effective packing density Duration of experiment Purified olefin Weight ratio Column height (cm) olefin to silica gel (Parts by weight) (w / v) (minutes) (parts by weight) 35.5 19.8 0.71 180 183 5: 2 50.0 29.1 0.68 240 355 7: 1 As can be seen from this data, the slurry relative to percolation saves a significant amount of time in the production of an olefin.

Claims (2)

Claims: 1. Process for cleaning C to C1s splitting wax or fission raffinate olefins, d a du r c h marked that one in these olefins Silica heated to at least 100 ° C and having a surface area of at least 500 m2 / g, slurries and that the impurities silicon dioxide containing compounds separates in the usual way. 2. The method according to claim 1, characterized in that the Allowing the temperature of the slurry to drop below 30 "C. References considered: U.S. Patent No. 2,459 442; British Patent No. 650 095; L. u. M. F i e s e r, textbook of organic Chemie, 1955, p. 103.