CS64491A3 - Process for producing white mineral oil intended for use in foodstuff industry - Google Patents

Abstract

The production of food grade quality white mineral oils from predominantly naphthenic or cycloparaffinic crude distillates heretofore have required acid treating using sulfuric acid followed by neutralization, water wash and possibly finishing step. Herein, however, three stages of hydroprocessing without any solvent extraction or acid treatment prior step are employed to produce the desired food grade quality white mineral oil having a trace of aromatic constituents therewithin. Specific steps are defined in the application in terms of the severity of the hydrogenation in the hydrotreating operation at each respective step; as well as the steps of separating gaseous constituents of the hydroprocessing product.

Description

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Technical field

BACKGROUND OF THE INVENTION The present invention relates to a method for producing mineral oil for food purposes. In particular, the invention relates to a process wherein naphthenic distillate is used as starting material, wherein the resulting oil contains only traces of aromatic substances.

Background Art

A variety of hydrocarbon processing techniques are known, from the beginning of research to modern methods for their processing.

There are nearly the same number of works describing the use of the carriage in hydrogenation and in the processing of large amounts of water. These procedures are already described in textbooks published just after the Second World War, such as The Textbook of Organic Chemistry, E. Wertheim, 2nd Edition, Blakiston Company, Philadelphia, Pennsylvania, 1947 and Unit Processes in Organic Synthesis, Groggins , ed. 3rd Edition, Mc.Braw Hill, New York, New York, 1947. As noted in these publications, good results can be obtained with careful selection of hydrogenation conditions.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a process in which a careful selection of conditions is achieved.

A number of processes are known in the known publications to obtain a white mineral oil with a quality suitable for food purposes, but these processes are costly and acidic, followed by non-neutralization in an adsorption tower, where it also occurs. to remove undesired components to form the resulting product. - 2

However, no method has yet been described that would enable the economical achievement of white mineral oil for food purposes without costly and laborious procedures such as acid treatment, neutralization and adsorption of unsuitable ingredients from the resulting product.

SUMMARY OF THE INVENTION

SUMMARY OF THE INVENTION It is an object of the present invention to provide an economical process for obtaining a white mineral oil for food purposes without the hassle of making the method.

These and other objects of the invention will be apparent from the following detailed description with reference to the accompanying drawings.

SUMMARY OF THE INVENTION The present invention provides a process for the production of white mineral oil for food purposes, wherein the naphthenic or cycloparaffin starting material is subjected to hydrogen treatment in three stages without solvent extraction and acid treatment to produce the desired quality product. which contains only aromatic hydrocarbon species.

SUMMARY OF THE INVENTION The present invention relates to a process wherein the naphthenic starting material is first hydrogenated, whereupon the gaseous constituents formed during the hydrogenation are separated, and further hydrogenation is carried out again, followed by separation of the gaseous constituents from this second stage and then the final hydrogenation is carried out in the third stage. which is milder than white mineral oil, suitable for food purposes.

The invention will be described, by way of example, with reference to the accompanying drawings. - 3 - Drawings

Figure 1 is a schematic diagram of known processes for the production of white mineral oil for food purposes.

FIG. 2 is a schematic diagram of a process according to the invention for obtaining a white mineral oil for food purposes.

Fig. 1 shows a known method. In this process, the naphthenic distillate is extracted with a solvent, a phenophenol or N-methylpyrrolidine to produce a hydrocarbon oil containing only 4-7% of aromatic hydrocarbons, which is then treated with acid. The lower fraction of this step is an acid slurry, while an extract that contains a high amount of aromatic compounds is obtained as the fraction of the top of the column after solvent extraction. Acid treatment is only traces of aromatic hydrocarbons in the outlet 15 after this treatment. The final stage is carried out in an adsorption tower 17 'filled with clay or a hydrogenation tower 17 can be included to reduce the traces of aromatic substances to achieve a good quality of the resulting oil of the 19 * /

In contrast, the process of the invention comprises a process wherein the naphthenic distillate containing 15 to 25% by weight of aromatic hydrocarbons is hydrogenated to produce a product in which the aromatic hydrocarbon content is reduced by 50 to 70%, so that the product contains 7 to 10% by weight of these hydrocarbons. This procedure is shown in FIG. 2 in step 1, in which the first tower 21 is included. The term "naphthenic distillates" is synonymous with the terms cycloparaffinic distillates. The aromatic hydrocarbon content of these distillates is usually 15 to 25% by weight. These new distillates are fed through inlet 23. In Fig. 2, hydrogen - 4 - is fed via line 25 in Fig. 2. Both components are mixed prior to entering the first tower 21 where hydrogenation of the hydrogenation catalyst is present. from the group VIIIA, preferably nickel and from the group VIA, preferably monobenzene at a temperature of 290 to 400 ° C, preferably 345 to 370 ° C, the partial pressure of hydrogen is 8.4 to 14 MPa, - preferably 10.5 to 12.6 MPa. The hydrogenated product exits the first tower 21 through the outlet 27. In the next step, the gaseous components of the hydrogenated product from the outlet 27 are separated from the liquid components and exited through the outlet duct 29. 21. After this step, the content of aromatic hydrocarbons in the liquefied product drops to 7 to 10% in outlet 33 »This fraction contains only about half of the aromatic hydrocarbons compared to the material from inlet 23 or less, which material is then fed to inlet 35 The second hydrogenation is also carried out in the presence of a hydrogenation catalyst containing a Group VIIIA metal, preferably nickel, and a VIA, preferably molybdenum, hydrogen partial pressure. it is in this second stage between 17.5 and 21, preferably 19.2 to 21 MPa, the temperature is 300 to 400, preferably 330 to 370 ° C. From the outlet 41, the product is fed to the second stripping tower 43, the gaseous components of the second stage are discharged via the outlet conduit 45. These gaseous components include, inter alia, hydrogen sulfide and ammonia. The resulting bottom product of the second stripping tower 43 at outlet 49 contains only about 1% of the aromatic hydrocarbons and is fed through the conduit 51 in which it is mixed with hydrogen from the supply line 53. mild conditions. In this final stage in the third hydrogenation process, the process is terminated by hydrogenation in the presence of a hydrogenation catalyst containing a Group 8A metal such as platinum, palladium or nickel, preferably platinum in the conventional form, hydrogen partial pressure it is in the range of 14 to 21, preferably 17.5 to 21 MPa, the temperature is only 190 to 315, preferably 230 to 290 ° C.

It should be noted that in all of these reactions, the use of a relatively high hydrogen partial pressure and a relatively low temperature facilitates hydrogenation to produce the desired product with a small amount of aromatic constituents in the liquid product without excessive swelling, which would result in undesired reduction in the boiling point of the resulting material.

In the illustrated embodiment, the materials in the outlet pipe 57 will contain only about 0.3% by weight or even less aromatic components. These traces of surfactants can be allowed in white mineral oil for food purposes. In particular, the polynuclear content of this type is less than 30 ppm. In carrying out the process, the naphthenic distillate is mixed with hydrogen at the desired partial pressure to hydrogenation which is carried out in the first tower 21. In the stripping tower 31, the gaseous components are separated from the liquid components so that the gaseous components are discharged through the outlet line 29 and the liquid components through the outlet 33 and then passed through the inlet 35 of the second hydrogenation tower 37. Hydrogen is again added to the material at the indicated partial pressure so as to hydrogenate at an elevated temperature in the presence of a suitable catalyst to reduce the aroma content of the product in outlet 41 The gaseous components are discharged through the outlet conduit. 45 The product at outlet 49 is fed to the third hydrogenation tower 55 and the resulting product is discharged therefrom through the outlet conduit 97. - 6 - From the foregoing, it is clear that the desired product, ie white mineral oil with a quality suitable for food Purpose in the outlet pipe 51 was produced by a process substantially different from the known processes for producing the same end product. Although the process of the invention has been described with respect to a preferred embodiment, it will be appreciated that various combinations and configurations of this process may be devised without departing from the spirit of the invention. Thus, all such modifications are also encompassed by the invention.

Claims (8)

- 7 - PATENT CLAIMS - // A process for the production of white mineral oil for food purposes, characterized in that the naphthenic starting material is continuously treated with a few steps of hydrogen treatment without any extraction solvent or acid treatment. Process according to Claim 1, characterized in that a) the naphthenic starting material in the first stage is subjected to hydrogenation and extraction with a solvent and without an acid treatment to reduce the aromatic hydrocarbon content by about 50%; (c) the product of step (a), after separation of the gaseous components, is passed to a second stage where it is hydrogenated to reduce the aromatic content to about 1 d) the gaseous components of the hydrogenation in step c) are separated and e) liquid after separation of the gaseous components, the product is hydrogenated in the final stage under milder conditions of white mineral oil to be introduced with quality, suitable food and only traces of aromatic substances. Process according to Claim 1, characterized in that (a) the naphthenic or cycloparaffinic distillate with an aromatic hydrocarbon content of 15 to 26% by weight is hydrogenated to produce a hydrogenated product in which the aroma content is reduced to about 50% t - 8 - b) the gaseous component the product of the hydrogenated product is withdrawn from the top of the tower, a product containing only half of the original aromatic content by weight is removed from the bottom of the tower; (d) the gaseous components of this second hydrogenation product are discharged over the tower head to form a second liquid product from the bottom of the tower, which contains only 1% and (e) the second product hydrogen The lowering of the tower is subjected to the final stage of hydrogenation under milder conditions, resulting in a natural mineral oil of the foodstuff containing only the steppes of aromatic substances. 4. A process according to claim 3, wherein the first hydrogenation step is carried out in a first tower in the presence of a nickel catalyst based on amolybdenum, the gaseous constituents of the product containing hydrogen sulfide and ammonia which are separated from the product in a stripping tower. A process according to claim 3 or 4, characterized in that the first stage hydrogenation is carried out under a hydrogen partial pressure of 10.5 to 12.6 MPa at a temperature of 345 to 370 ° C. 6. Process according to claim 3, 4 or 5, characterized in that the second stage is carried out in a second hydrogenation tower using a non-nickel-molybdenum catalyst, the gaseous components of this second stage containing hydrogen sulfide and ammonia which are separated off. from the second stage product in the second stripping tower. Method according to claim 6, characterized in that the hydrogen partial pressure is 19.2 to 21 UPa and the temperature is 330 to 370 ° C. | A process according to any one of claims 3 to 7, characterized in that the hydrophenyl is carried out in the final hydrogenation tower in the presence of a platinum catalyst for reforming. Process according to Claim 8, characterized in that the last hydrogenation is carried out with an additional hydrogen pressure of 17.5 to 21 MPa and at a temperature of 230 to 290 ° C. X'í: