DE1076297B - Process for the preparation of an essentially oil-free petroleum paraffin mixture - Google Patents

Description

Process for making a substantially oil-free petroleum paraffin blend The invention relates to the manufacture and recovery of hydrocarbon petroleum paraffins with advantageous ductility, flexibility and a high resistance to rapid cooling. Another object of the invention is the production of such Paraffins by incorporating certain soft paraffins that are normally used can be eliminated during dewaxing in the previously known manner.

They are used for the production of paraffins and microcrystalline paraffins different working methods are applied from mineral oil distillates and residues has been proposed. It is known to use paraffinic mineral oils or fractions to dewax such by cooling; usually after adding a solution and / or diluent. Depending on the type of oil and the working conditions, such as lowest refrigeration temperature, speed of cooling, fashion cooling, etc., the paraffins thus obtained have certain disadvantages, their elimination would be desirable. Certain measures have been taken in this direction Recovery of soft paraffin components from the soft paraffin fractions, which are usually discarded in a de-oiling process.

Separate de-oiling of the soft paraffin fraction is common associated with difficulties, e.g. B. because of the low melting point of the coming wax paraffins and the relatively low paraffin content of the soft ones Paraffin fraction. As a result, it has been found that in dewaxing A paraffin cake made from a soft paraffin fraction tends to split and consequently when washing out the oil from which the cake is to be separated, causes increased difficulty, So contain deoiled soft paraffins, which by previously known methods have been made, usually unduly large Shares of 01 that cause a deterioration in the quality of the paraffin. About that in addition, when a soft paraffin is de-oiled according to previously known methods a number of the desirable types of high ductile, low melting, soft Separated wax in the oil-containing solvent solution. So go the factions those with regard to increasing ductility and behavior at low temperatures ornamental paraffins could have the most beneficial effect, lost. In addition, the soft paraffin fraction in view of the difficulty of satisfactorily dewaxing them normally fed to a cracking process or otherwise under such circumstances "> Pus-treated that their value is extremely low compared to the usual ones Dewaxing processes.

Measures were taken earlier when removing oil from waste wax in order to incorporate soft paraffin fractions as far as possible by lowered the deoiling temperature to such a point that the soft paraffins crystallized together with the higher melting paraffin fractions. While in this way it is possible to separate a certain proportion of the soft waxes, the use of the low de-oiling temperature also causes an increase in the viscosity of the oil from which the paraffins have to be separated. Because This increase in the viscosity of the oil tends to cause it to stick to the surface of the oil Wax crystals remain, and as a result, it is often found that the product obtained in this way has too high a proportion of oil. In addition, it results that when using a low deoiling temperature for the waste paraffin As far as possible recovery of the otherwise in the filtrate of a deoiling treatment discarded soft waxes the result is determined by the amount of treated wax Soft paraffins contained in the raw material.

It is therefore when the ratio of soft paraffins is either excessive is high or unduly low, note that the resulting mixture of hydrocarbon paraffins does not meet the requirements of the consumers of the paraffin, in particular the Manufacturer of milk cups or the manufacturer of coated papers and the like

Another disadvantage of the separate deoiling of soft paraffins (um to be independent of the particular inherent relationship from soft waxes to other waxes) there is a need to maintain a variety of storage options while maintaining the separation of the different products.

It is an object of the present invention to provide the method for To improve the manufacture of paraffin mixtures. Another - subject relates on .the improvement of the properties of hydrocarbon paraffins lower temperature. The invention is particularly concerned with a method for Manufacture of paraffin mixtures that have an improved resistance to breaking with sharp cooling. A method is also within the scope of the invention indicated for the improvement of the ductility of microcrystalline waxes. Further Successes and advantages result from the description below: It is found that improved properties of paraffin especially at low temperatures can be obtained by adding paraffin components to the paraffin mixtures incorporated in substantially the same boiling range as that of ordinary ones Paraffin wax or microcrystalline waxes that were originally used in the mixtures are present, but are practically normally lost in the de-oiling treatment.

According to the invention there is an essentially oil-free petroleum paraffin mixture made by using a paraffinic petroleum feedstock such as a distillate lubricating oil fraction or a residual oil containing microcrystalline waxes, with a solvent dewaxed to obtain an essentially paraffin-free oil and a raw wax is, whereupon part of the raw wax is de-oiled with solvent, and that then the separated oily soft wax with a second part of the original Slack wax is mixed and the mixture is subjected to solvent de-oiling.

The above brief description of the procedure and other measures and benefits are better understood when considering the use of the Drawing showing an arrangement of an apparatus for carrying out the method according to of the present invention for the purpose of obtaining an improved paraffin blend.

A paraffin-containing oil is transferred from a storage container 1 to a distillation zone 2 transferred, in which the oil is separated into fractions according to the boiling range will. A fraction is denoted by A. This faction is on the line 3 and pumped by pump-4 to a point where they are treated with a selective solvent for aromatic compounds flowing in from the container 5 is mixed. That The mixture is fed to a separation vessel 6 in which a solution of the aromatics is separated off and is removed while the paraffin-containing raffinate is treated with a dewaxing agent is mixed from the container 7 and passed into a heater 8, in which the paraffin-containing raffinate is practically completely dissolved in the solvent. Then it reaches the cooling device 9, in which paraffin wax contained in the mixture crystallized out.

The paraffin-solvent-oil mixture is used to separate the paraffins of the remaining components of the: mixture passed into a filter 10. The filtrate represents a dewaxed oil which is dissolved in a solvent and in a solvent recovery system 7 is passed, from which a dewaxed Oil has got into the storage container. The raw paraffin that remains on the filter comprises a mixture of the paraffins present in the paraffin-containing C51 contaminated with 2 to 60 percent by weight oil. This mixture becomes one by the pump 11 Point in line 12, at which it is with a de-oiling solvent mixed from a recovery system 13 and then fed to a heater 14 to dissolve the slack wax in the solvent. Then it is used for the purpose Precipitation of the paraffin in the cooler 15, and the precipitated paraffin is on the filter in the device -16 won.-The filtrate on the filter 16 consists of a solution of a soft paraffin in the solvent. This solution is made with the help of of the pump 17 to the solvent recovery system 13, in which the solvent is separated from the soft paraffin. The soft paraffin gets then via line 18 into a mixing vessel 19; in which it is in appropriate proportion is mixed with further amounts of a waste paraffin from the filter 10. solvent from solvent recovery plant 13 or from other sources then added to the mixture which is fed via line 20 to heater 21 in which the mixture of soft paraffin and raw paraffin in one de-oiling acting solvent is practically completely dissolved, and then over the Line 22 enters a device 23 for cooling, in which the mixture of paraffins and light paraffins are precipitated from the oil present, with the C51 in the Solvent remains dissolved. The mixture is passed through line 24 to the filter 25 to separate the precipitated paraffins while the solution of oil and solvent is passed into the solvent recovery system 26. Traces of solvent are separated from the paraffins in the system 27, whereby a paraffin wax is obtained which has more favorable behavior at lower temperature or particularly in the case of microcrystalline waxes, has favorable ductility.

In the case of the microcrystalline wax mixtures, it can in particular it may be desirable to further process the particular paraffin wax product, e.g. B. by a deoiling treatment with solvent at high temperature; around a relatively high-melting hard wax on one side and a more ductile one, On the other hand, to achieve easily adhering crystalline wax.

When using the system shown in the drawing for treatment The microcrystalline paraffins normally occur in microcrystalline paraffin mixtures in the residual oils and are therefore at a point at the lower end of the distillation column 2, d. H. not obtained from a distillate fraction.

From the foregoing description it can be seen that the essential object of the present invention is the incorporation of soft paraffin waxes from the filtrate from filter 16. The same goal cannot even come close to being achieved if the soft paraffins are returned to a point in the apparatus which is located before the production of the waste paraffin, since this soft paraffin fraction would then for the most part be separated in the dewaxed oil , which in an undesirable manner the pour point of the oil would prevent the soft paraffins in the wax mixtures from being used where they are desired.

Even if those in the relevant technology for dewaxing are good known working conditions applied = that can be proportionately low It is - but - preferable to use dewaxing temperatures Advantages of the present invention are also achieved when normal Dewaxing temperatures are present.

The paraffinic petroleum oils made according to the present invention can be treated include petroleum distillate fractions, especially distilled Lube oil fractions, as well as residual oils - such as so-called "short residues" and the like. Like. It is known that the paraffin waxes in large: amount in the distillate fractions (with the exception of the high-melting paraffins that may be present in the residues) are contained, while the non-highly crystalline paraffins are normally contained in the residual oils either alone or in combination with paraffins Melting point can be included. The quantitative proportions of paraffin in these Fractions are known in the relevant art. The main part of the present Mixtures in that they are petroleum containing paraffin wax include normal and isoparaffin and cycloparaffin hydrocarbon waxes with single melting points in the usual range of about 43.3 to 73.9 ° C, in particular between about 54.4 to 62.8 ° C. The distillate paraffin waxes usually predominate in the normal paraffins and can consist of a single wax, but are usually a mixture of relatively closely related paraffin waxes. Common practice persists in that a broad fraction of lubricating oil is distilled, either before or after redistillation for the purpose of producing the relatively narrow-boiling waxy Oil fractions are dearomatized.

The remaining oils usually contain what is called >> Bright stock « is known and a residue lubricant with high viscosity in combination with microcrystalline waxes, any high-melting paraffin waxes that are still present can, and - if a mixed basic crude oil has been processed - with asphaltic Represents factions. Asphaltic compounds can be extracted with propane or by other means prior to the dewaxing treatment.

The original dewaxing treatment is done with the help of selective solvents which are known in the relevant art. at Carrying out the improved method of the present invention will be Dewaxing and oil removal treatments carried out by removing the waxy Oils together with oil solvents or thinners, such as ketones with fewer than 8 carbon atoms per molecule, such as acetone, methyl ethyl ketone, methyl propyl ketone or methyl isobutyl ketone, cools. Also alcohols with less than 8 carbon atoms per molecule, such as ethyl alcohol, isopropyl alcohol or n-propyl alcohol, are suitable. Mineral oil, halogenated hydrocarbons such as ethylene dichloride and dichloroethylene, Hydrocarbons with fewer than 8 carbon atoms in the molecule, such as benzene, toluene; ethane, Ethylene, propane, propylene, butane or isobutane; - can also be used. . Mixtures of solvents or diluents. like benzene, together with methyl ethyl ketone can also be used, as in the dewaxing processes According to the prior art, the precipitation is: Dewaxing with solvent = and "- the de-oiling can be carried out at temperatures appropriate for the purpose are known -and using quantitative ratios between solvents and paraffinic - oil or oily paraffin. as they do in technology are known. The dewaxing temperatures are when using polar solvents usually in the range of about -26.1 to 9.4 ° C; provided the dewaxing solvents (polar or non-polar) in quantities of about 1 room file to 5 room parts per room part of the waxy oil are present. The temperatures during dewaxing are if only low molecular weight alkanes (e.g. propane) are used, between -40 up to 17.8 ° C. Dewaxing usually leads to the formation of a dewaxed one Oil and a slack wax, the latter term being used for a wax product made with a greater or lesser amount of oil or oily Is contaminated. This slack wax usually contains from about 2 to about 60 percent by weight oil. However, this number can still fluctuate within very wide limits. In the case of de-oiling treatments, the amount of solvent is usually increased to 2 to 7 parts by volume of solvent per part by volume of the oily wax, the deoiling temperatures usually between about 0 and 18.3 ° C.

The soft wax fractions are normally eliminated in the filtrate from de-oiling to raw waxes, insofar as they are used for the production of distillate paraffin contribute.

The soft paraffins include mixtures of highly branched or naphthenic Wax with significantly lower melting points and other, more plastic properties than the waxes with an almost straight-chain structure and the same molecular weight. Consequently high-melting waxes can be present within a certain narrow boiling range, which represent typical paraffin waxes, as well as low-melting waxes which in their properties approach the wax fractions, which are normally called the filtrate can be eliminated from the de-oiling of a raw wax. As a result, the Boiling ranges of the waxes in the soft wax fraction, roughly speaking in the same Order of magnitude with the boiling range of paraffin waxes or microcrystalline waxes, which are present in the same petroleum fractions that are subjected to the treatment.

The soft wax compounds can best be described by Reference to a special example according to which the soft waxes were de-oiled, in order to obtain a so-called "plastic" wax. A paraffinic lubricating oil distillate with the boiling range of 343.5 to 510 ° C (at atmospheric pressure) is subjected to a dewaxing treatment with solvent using known, selective dewaxing solvents subject. This treatment agent preferably consists of a mixture of one low molecular weight, aliphatic ketone and an aromatic hydrocarbon, such as benzene or toluene, in a volume ratio of 3: 1 to 1: 3 (preferably 2: 1 until 12). There is a particularly preferred pair of dewaxing agents from methyl ethyl ketone and toluene in the mixing ratio between about 2: 1 and 1 c 2 space parts. It becomes a sufficient amount of the dewaxing solvent applied to the waxy lubricating oil at temperatures above about 48.9 ° C completely to dissolve, whereupon the solution to a dewaxing temperature, preferably in the order of magnitude between about -26.1 and r-9.4 ° C when using polar solvents or -40 to --17.8 ° C when using lower alkanes as solvents will. At around the dewaxing temperature, the raw wax becomes from the dewaxed one Oil filtered off or centrifuged off. The raw wax then undergoes a de-oiling treatment with solvent, preferably using the same type of de-oiling agent, subject. The raw wax is dissolved in the solvent, preferably in methyl ethyl ketone in mixture with toluene, usually at an elevated solution temperature, whereupon cooled to a temperature between about 9.7 and about 10 ° C and at the latter Temperature the refined paraffin wax is filtered off. This paraffin wax is further processed by known methods, e.g. B, by reslurrying or by washing on a filter to obtain a completely purified paraffin wax obtained which has a melting point between about 57.2 and about 62.8 ° C.

The soft wax mixture that remained dissolved in the solvent is in turn subjected to a de-oiling treatment by either the present solution cools to a point where the plastic waxes crystallize out, or by removing a sufficient amount of the solvent, to get a more concentrated solution of the soft wax, so that a lighter one to be achieved Entöllungstemper atur can be used. Preferably that will Soft wax dissolved in about 2 to about 6 parts by volume of a de-oiling agent per part of space of the soft wax, heated to a temperature on the order of 48.9 to 71.1 ° C and cooled to a temperature between about -1.1 and 7.8 ° C, being on the last-mentioned temperature limit, the plastic waxes separate and through mechanical separation (centrifugation or filtration) can be obtained. To the Remove the majority of the contaminating oil from the precipitated waxes, the waxes obtained in the manner described above are subjected to a Laundry or a slurry or both treatments in the temperature range of Filtration to obtain the desired plastic wax.

The product thus obtained has exceptional properties which have not previously been found in any wax known from the prior art. It has a melting point in the range of about 42.2 to about 47.2 ° C, a viscosity between about 35 and 45 SSU to 98.9 ° C, a refractive index at 70 ° C between about 1.4365 and 1.4500 as well an oil content (determined by the standard ASTM method) of less than about 0.5%. The penetration of the wax at 25 ° C is between about 40 and 80 mm / 10 according to ASTM method D 1321 54 T.

It is clear that these plastic waxes in the invention Process cannot be isolated in isolation, but in a cycle to combine with further proportions of raw wax from the same petroleum fraction are returned, whereupon the combination of soft and raw wax is then de-oiled, uni the wax mixture to obtain which, according to the invention, has been found to be superior Properties in terms of ductility, flexibility and resistance to rapid cooling.

In order to explain the method according to the invention even further, are Examples are given below. A raw wax was used for the comparative tests obtained by dewaxing a mid-range boil Lube oil distillate (Texas crude oil) that was used prior to dewaxing treatment Solvent had been extracted. The raw wax contained about 8 percent by weight Oil. In the procedure used for the comparative study, the raw wax became a dewaxing treatment using a mixture from methyl ethyl ketone and toluene subjected. The dewaxing temperatures were either 1.7 to 9.4 ° C (see table). The combination of Soft wax when mixed with further proportions of the same raw wax resulted in changing proportions (see table) in the manufacture of wax products with improved behavior at low temperature, as also indicated in the table is.

Sample A explains the process of de-oiling a raw wax a lubricating oil fraction with a medium boiling range or one obtained from it Wax at normal temperature (1.7 ° C) to form a relatively hard one Wax with a melting point of 59.7 ° C. The wax is relatively little flexible and has a strong tendency to break when cooled quickly by cold liquids will. The latter property makes this wax particularly unsuitable for Covering cardboard containers that are used to fill cold liquids, such as milk, should serve.

The de-oiling of the same raw wax at a relatively low one Temperature (pattern B) produces a wax product that is slightly softer, more pliable and in behavior at low temperatures is better than the sample A. The achieved However, improvement in these properties is limited.

The method of the present invention is preferred in one Embodiment illustrated by de-oiling to obtain samples C, D and E. In these experiments 1, 3 or 5 parts of soft wax were added to 4 parts Raw wax and the mixture at a relatively low oil removal temperature (9.4 ° C) de-oiled. The waxes obtained were relatively soft paraffin waxes with increased flexibility. They showed little or no tendency to break when examined at low temperature. The wax obtained would be inexpensive for use in cases where increased flexibility is beneficial, d. H. in the case of coated bread casings or as a coating for casings for frozen food. The wax would also work well as a coating for containers made of cardboard, which are used to store cold liquids such as milk or other drinks.

The process is not limited to low de-oiling temperatures, but can also be used at normal de-oiling temperatures such as 1.7 ° C. The oil removal treatments, which led to samples A, F, G and H show how the treatment in a A deoiling temperature of 1.7 ° C is effective. When the proportion of soft wax in the starting material for the de-oiling treatment from 0 to 1 and then to 3 and 5 parts of soft wax 4 parts raw wax increases, the melting point of the end product decreases obtained wax from the de-oiling operation. In addition, the hardness is reduced. The flexibility is increased somewhat, and the behavior against breakage at low temperatures gets better.

This basic rule of adding a soft wax to a raw wax with the same boiling range and de-oiling the combination of these substances is applicable to the production of flexible waxes also of other origin than the starting material described above with an average medium boiling range. For example, the process is applicable to the lower boiling wax distillates in which it is desired to produce a wax that contains an increased concentration of low melting components. The process can also be used for high-boiling distillates, in order to produce waxes with a higher melting point and good flexibility. Finally, it is also suitable for residues to produce microcrystalline waxes of high ductility and with improved sealing (fusing) properties. . - pattern .. F I. G@._ Source material Waste wax, parts. . . . . . . . . . . . . . . . . 1 1 4 4 4 4 4 4 Soft wax, parts .... . . . .. .. ... . .. 0 0 1 3 5 1 3 5 Freezing point, o C, ASTM D 938 55 55 53.3 51.1 48.9 53.3 51.1 48.9 Oil content, weight percent, ASTM D 721 ................... 8 8 8 17 21 18 17 21 Laboratory oil removal standard. Nied. Nied. Nied. Nied. Standard. Standard. Standard. temp. temp., temp. temp. I temp., temp.! Temp. I Temp. Solvent, MÄK / toluene. . . . . ... 50 / 50I 50/50 50/50 50/50 50/50 50/50 50/50 50/50 First dilution, ratio ...... 4 4 4 4 4 4 4 4 Second dilution, ratio ..... 2 2 2 2 2 2 2 2 Recrystallization, temperature of Filter feed, o C. . . . . . . . . . . . . . . 1.7 -9.4 -9.4 9.4 -9.4 1.7 1.7 1.7 Recrystallization, wash ratio. 3 3 3 3 3 3 3 3 Renewed dilution ratio .... 3 3 3 3 3 3 3 3 Refill filter, temperature, o C 1.7 -9.4 -9.4 -9.4 -9.4 1.7 1.7 1.7 New wash ratio .......... 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 Yield, percent by weight Cake ........................... 76.8 85.2 74.3 68.6 68.6 68.5 57.7 55 , 5 Properties of the wax product Melting point, o C, ASTM D 87 .... 59.7 I 58.1 57.4 55.0 53.2 58.5 56.9 55.5 Oil content, weight percent, ASTM D 721 .................. no 0.1 0.1 0.4 0.4 no no 0.1 Hardness, needle, penetration at 25 ' C, mm / 10 ASTM D 1321 ........... 11 13 15 21 25 13 15 19 Flexibility at 22.8 ' C, angle of refraction, Degree .......................... 8 12 17 23 33 16 17 17 Breaking resistance at low temperatures rature in inches of the cracks, cm ....... 88.9, 63.5! 11.4 15.2 1 none 76.2 6.4 1.3 The test methods used to obtain the numerical values given above can be described as follows: Test to test the resistance to fracture at low temperature.

5 millimoles of melted wax were waxed at 110 ° C Poured milk bottle from cardboard, whereupon the wax solidifies and the waxed container for 1 hour at 22.8 ° C and 50% relative humidity stored. The waxed container was then quickly quenched by immersion in water at 1.7 ° C for 1 minute, which in itself favors the formation of cracks will. The length of the cracks in inches was determined using a map odometer. A good wax shows little or no cracking. Wax flexibility test From a wax film, which had been produced by solidifying in water, became cut out a sample measuring 5.08-1.27-0.0508 cm. The sample was 1 hour exposed to the test temperature and then placed in a flexibility tester. The flexibility test fixture consists of two parts. A part is hiring Pair of rotating rotatable claws, in which one end of the wax sample is held will. The second part is a fixed arm that controls the movement of the opposite Prevents the end of the wax sample from rotating in the direction of rotation when the claws are rotated will. One end of the specimen is inserted into the jaws and these are rotated, around the opposite end of the specimen straight into contact with the fixed arm bring. This position is regarded as the zero point. The claws will then rotated at a speed of 180 ° per minute, creating the wax sample is bent. The angle at which the specimen tears is measured with the help of a protractor, which is attached to the claws, measured. The results of five samples will be used for calculating an average value, and that value is the Tear limit.

Claims (3)

PATENT CLAIMS: 1. A process for the preparation of an essentially oil-free petroleum paraffin mixture, characterized in that a paraffin-containing petroleum raw material, such as a distillate lubricating oil fraction or a residual oil containing microcrystalline waxes, is dewaxed with a solvent to obtain an essentially paraffin-free oil and a raw wax, whereupon a part of the raw wax is de-oiled with solvent, that then the separated oily soft wax is mixed with a second part of the original raw paraffin and the mixture is subjected to a solvent de-oiling. 2. Procedure according to Claim 1, characterized in that a distillate lubricating oil fraction with a Boiling range between 343.5 and 510 ° C at 760 mm Hg pressure is used. 3. Procedure according to claim 1, characterized in that the paraffin mixture when used of a residual oil recrystallized after de-oiling and a paraffin with high Melting point of a wax containing microcrystalline soft paraffin components is separated.