CZ279524B6 - 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

Technical field

The invention relates to a process for the production of mineral oil for food purposes. More particularly, the present invention relates to a process in which the naphthenic distillate is used as the starting material, the resulting oil containing only traces of flavorings.

BACKGROUND OF THE INVENTION

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

There are almost the same number of works describing the use of hydrogen in hydrogenation and in the treatment using large amounts of water. These processes are also described in textbooks that were published shortly after World War II, 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, McGrav Hill, New York, 1947. As emphasized in these publications, good results can be obtained by carefully selecting the hydrogenation conditions.

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

Known publications describe a number of processes for obtaining a white mineral oil of a food grade quality, but these processes are expensive and require the use of acids followed by neutralization in the adsorption tower, where undesirable components are also removed. to give the final product.

However, a process that would make it possible to economically achieve white mineral oil for food purposes without expensive and laborious processes such as acid treatment, neutralization and adsorption of inappropriate ingredients from the resulting product has not been described yet.

SUMMARY OF THE INVENTION

SUMMARY OF THE INVENTION It is an object of the present invention to provide an economical process for obtaining white mineral oil for food purposes without the laborious procedures with which this method has hitherto been carried out.

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

SUMMARY OF THE INVENTION The present invention provides a process for the production of white mineral oil for food use by subjecting a naphthenic or cycloparaffin feedstock to a three-stage hydrogen treatment without solvent extraction and without acid treatment to produce a product of desired quality containing only traces of aromatic hydrocarbons .

The present invention relates to a process in which the naphthenic starting material is first hydrogenated, after which the gaseous components are separated,

The hydrogenation is then carried out again, followed by separation of the gaseous components from this second stage, and then in the third stage, the final hydrogenation, which is milder, yields the desired white mineral oil suitable for food purposes.

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

Drawings

FIG. 1 is a schematic diagram of known processes for producing white mineral oil for food purposes.

Fig. 2 is a schematic diagram of a process according to the invention by which white mineral oil for food purposes can be obtained.

FIG. 1 shows a known method. In this process, the naphthenic distillate is extracted with a solvent such as phenol or N-methylpyrrolidine to produce a hydrocarbon oil which contains only 4-7% aromatic hydrocarbons, which is then treated with acid. The bottom fraction of this step is acid sludge, whereas the solvent from the top of the column yields an extract containing a high amount of aromatic compounds. After the acid treatment, only traces of aromatic hydrocarbons are left 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 traces of flavorings to achieve good quality of the resulting oil at outlet 19.

In contrast, the process according to the invention comprises a process in which 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%. % of these hydrocarbons. This process is illustrated in FIG. 2 in Step 1, in which the first tower 21 is incorporated. The term naphthenic distillates is synonymous with the terms cycloparaffin distillates. The aromatic hydrocarbon content of these distillates is generally 15 to 25% by weight. These naphthenic distillates are supplied through inlet 23. Hydrogen is supplied via line 25 in Figure 2. The two components are mixed before entering the first tower 21 where hydrogenation occurs in the presence of a hydrogenation catalyst comprising Group VIIIA metals, preferably nickel and Group VII. VIA, preferably molybdenum at a temperature of 290 to 400 ° C, preferably 345 to 370 ° C, the partial pressure of hydrogen is from 8.4 to 14 MPa, preferably 10.5 to 12.6 MPa. The hydrogenated product exits the first tower 21 via 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 are discharged through the outlet line 29. This outlet line 29 discharges hydrogen sulphide and ammonia from the stripping tower 31 as hydrogenation gas products in the first tower 21. % of aromatic hydrocarbons in the liquid product to 7 to 10% in the outlet

33. This fraction contains only about half of the aromatic hydrocarbons compared to the input 23 material, or even less. This material is then fed to the inlet 35 of the second hydrogenation

At the inlet 35 hydrogen is added through the inlet pipe ^at 39. The second hydrogenation is also carried out in the presence of a hydrogenation catalyst comprising a Group VIIIA metal, preferably nickel, and a Group VIA metal, preferably molybdenum, hydrogen partial pressure. in this second stage, it is in the range of 17.5 to 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 from the second stage being discharged through the outlet conduit 45. These gaseous components comprise inter alia hydrogen sulfide and ammonia. The resulting product from the bottom of the second stripping tower 43 at the outlet 49 contains only about 1% aromatic hydrocarbons and is passed through a line 51 in which it is mixed with hydrogen from the feed line 53. In the final stage hydrogenation is carried out in the third hydrogenation tower 55 conditions.

In this final stage in the third hydrogenation tower 55, the process is terminated by hydrogenation in the presence of a Group 8A metal hydrogenation catalyst such as platinum, palladium or nickel, preferably platinum in conventional form, the hydrogen partial pressure being in the range of 14-21, preferably 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 relatively high hydrogen partial pressure and relatively low temperature facilitates hydrogenation to produce the desired product with a small amount of aromatic components in the liquid product without too much cracking resulting in undesirable lowering of the boiling point of the resulting material.

In the illustrated embodiment, the materials in the outlet conduit 57 will contain only about 0.3% by weight or less of the aromatic components. These traces of these substances can be accepted in white mineral oil for food purposes. In particular, the content of polynuclear substances of this type is less than 30 ppm.

In the process, the naphthenic distillate, after mixing with hydrogen at the desired partial pressure, leads to hydrogenation 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 via the outlet conduit 29 and the liquid components. through the outlet 33 and then through the inlet 35 to the second hydrogenation tower 37. Hydrogen at the partial pressure is again added to the material so that hydrogenation occurs at elevated temperature in the presence of a suitable catalyst to reduce the flavor content of the product in outlet 41, the gaseous component. The product in outlet 49 is then fed to the third hydrogenation tower 55. From there, the resulting product is discharged through outlet line 57.

From the foregoing, it is apparent that the desired end product, i.e., white mineral oil of food grade quality, in the outlet conduit 57 has been produced by a process substantially different from known processes for producing the same end product.

Although the method of the invention has been described in connection with a preferred embodiment, it is clear that various combinations and configurations of the process can be devised without

This has departed from the spirit of the invention. All such modifications are therefore also included in the scope of the invention.

Claims (9)

PATENTOVÉ Claims CLAIMS 1. A process for the production of white mineral oil for food use from a naphthenic feedstock without the use of a solvent or acid during a continuous process, wherein the feedstock is treated in a series of successive stages by treatment with hydrogen, characterized in that i) the starting material is processed in three hydrogenation stages, ii) the hydrogenation in the first stage is carried out at a temperature of 288 to 399 ° C and at a partial hydrogen pressure of 8.2 to 13.7 MPa, iii) the feed to the second stage comprises a liquid product from the first and iv) the feed to the third stage comprises the liquid product of the second stage. Method according to claim 1, characterized in that it is: (a) in the first hydrogenation step, reduce the flavoring content of the source material to approximately 50%; b) gaseous components are separated from the hydrogenation liquid product of step a), (c) after separation of the gaseous components, the proportion of flavorings in the liquid product from the first stage through the second hydrogenation stage is reduced to approximately 1%; d) gaseous components are again separated from the hydrogenation product of step c); e) the liquid product of step c) is subjected, after separation of the gaseous components, to a final hydrogenation step under milder conditions than in steps a) and c) to obtain a white mineral oil suitable for food purposes. Process according to claim 1 or 2, characterized in that naphthenic or cycloparaffin distillate with a flavoring content in the range of 15 to 25% by weight is used as starting material. The process according to claim 3, wherein the first hydrogenation step is carried out using a catalyst based on nickel and molybdenum, the gaseous component of the hydrogenation The product contains hydrogen sulfide and ammonia, and these are separated by stripping. Process according to claim 3 or 4, characterized in that the hydrogenation is carried out at a hydrogen partial pressure of 10 to 12.4 MPa and a temperature of 343-371 ° C. Process according to any one of claims 2 to 5, characterized in that the second hydrogenation stage is carried out using a catalyst based on nickel and molybdenum, the gaseous components from the second hydrogenation stage comprising hydrogen sulphide and ammonia and separated by stripping. The process according to claim 6, characterized in that it is carried out at a hydrogen partial pressure of 19 to 20.7 MPa and at a temperature of 329 to 371 ° C. Process according to claims 2 to 7, characterized in that the final, milder hydrogenation is carried out in the presence of a platinum reforming catalyst. The process according to claim 8, wherein the hydrogenation is carried out at a hydrogen partial pressure of 17.2 to 17.2 20.7 MPa at 232 - 288 ° C.