JP3062701B2 - Formulation of food grade quality white mineral oil - 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

DETAILED DESCRIPTION OF THE INVENTION

[0101]

The present invention relates to a process for producing white mineral oil of food grade quality. More particularly, the present invention relates to a process for producing food grade white mineral oil containing only trace amounts of aromatic hydrocarbons from a naphthenic distillate as a feedstock.

[0092]

The prior art is well equipped with various references on how to treat hydrocarbons. These range from techniques during the Great Depression to modern methods of treating hydrocarbons.

There is almost the same number of documents for using hydrogen in terms of hydrogenation and hydroprocessing. E. Werthe, two books published shortly after World War II
im by The Textbook of Organic Ch
emistry), 2nd edition, Blakiston Co.
mpany), Philadelphia, Pennsylvania, 194
7 years and "Unit Process in Organic Synthesis"
es in Organic Synthesis), edited by Groggins, No. a3
Edition, McGraw Hill, New York, New York, 1947. As pointed out in these books, careful management of hydrogenation can give good results. The present application intends to use such meticulous control.

While the prior art has conceived a number of methods to obtain food grade quality white mineral oils, they are always expensive and still provide acid treatment, neutralization, removal of undesired components and end products. In this case, an adsorption tower or the like was used to obtain the product.

In particular, the prior art describes the economics of producing food-grade white mineral oil without expensive labor-intensive steps such as acid treatment, neutralization and adsorption of unwanted components from the product. Could not provide a strategic method.

[0086]

Accordingly, it is an object of the present invention to provide an economical process for producing food grade white mineral oil without the labor intensive processes of the prior art.

A particular object of the present invention is to provide an economical continuous flow process for producing food grade white mineral oil without the labor intensive processes of the prior art. These and other objects will become apparent when considering the matter described below, particularly with reference to the accompanying drawings.

[0098]

According to one aspect of the present invention,
Subjecting the naphthenic or cycloparaffinic feedstock to a three-stage hydrotreatment without prior solvent extraction or acid treatment to obtain the desired final quality containing only traces of aromatic hydrocarbons or carbon. A method for producing a food grade quality white mineral oil is provided.

According to another aspect of the invention, the naphthenic feed is first hydrogenated, the gaseous components formed during the hydrogenation reaction are separated, and then subjected to a second stage hydrotreatment or hydrogenation. A method is provided for separating the gaseous components produced by this second stage hydrogenation and then subjecting it to a less severe third hydrotreating step to produce the desired food grade white mineral oil.

The specific reaction conditions for each step will be described below.

FIG. 1 shows a conventional method for producing food-grade white mineral oil. Here, the naphthenic distillate is extracted using a solvent such as phenol or N-methylpyrrolidine to produce a hydrocarbon oil containing about 4-7% aromatic carbon, which is subjected to an acid treatment. The bottoms fraction recovered from the acid treatment is subsequently discharged as acid sludge, whereas the solvent extract containing a high concentration of aromatics from the first stage solvent extraction is recovered as bottoms product . After the acid treatment, the hydrocarbon oil containing traces of aromatic carbon or aromatic hydrocarbons enters line 15 leading from the acid treatment unit. A finishing process consisting of an adsorption tower 17 using clay or a hydrotreating tower 17 using hydrogen reduces residual traces of aromatic hydrocarbons and produces a satisfactory food grade white mineral oil in the effluent line 19. Let it.

In contrast, the method of the present invention provides
A naphthenic distillate containing aromatic carbon at a concentration of 25% by weight is subjected to hydrogenation to produce a hydrogenated product,
About 50-70% of the aromatic hydrocarbons is reduced, resulting in an aromatic carbon content of 7-10% by weight). This is shown in FIG. 2 and is also referred to as tower 21 in stage 1. The term "naphthenic distillate" is synonymous with cycloparaffinic distillate. Typically, these distillates contain about 15-25% by weight aromatic carbon. These naphthenic distillates enter at line 23 in FIG. Hydrogen is supplied through line 25 in FIG. Both feed components are mixed prior to entering stage 1, in stage 1 in the presence of a hydrogenation catalyst comprising a Group VIIIA metal component (preferably nickel) and a Group VIA metal component (preferably molybdenum). 550-750 ° F (preferably about 650-700 ° F)
° F) at 1200-2000 pounds per square inch gauge (psig) (preferably about 1500-1800
Hydrogenation is performed with a hydrogen partial pressure of pounds per square inch gauge). Thereafter, the hydrogenation product leaves column 21 via line 27.

In the next step, the gaseous component of the hydrogenation product in line 27 is separated from the liquid component and
Spill out of. An overhead line 29 carries hydrogen sulfide and ammonia from the stripper 31, among other things, as gaseous products of the hydrogenation reaction carried out in the hydrogenation tower designated as stage 1 21. After this process, the aromatics content of the liquid component will drop to about 7-10% aromatics in the liquid bottoms draw from the stripper in line 33. These liquid bottoms containing about half or less of the aromatic carbon in the initial feed in line 23 are then sent through line 35 to a second hydrogenation tower 37. This liquid bottoms in line 35, the hydrogenation product from the first stage, is mixed with hydrogen through line 39. The second hydrogenation is carried out in the presence of a hydrogenation catalyst comprising a Group VIIIA metal component (preferably nickel) and a Group VIA metal component (preferably molybdenum) at 2500-30.
00 psig (preferably 2750-3000 psi
g) at a partial pressure of hydrogen and a temperature of 575-750 ° F. (preferably about 625-700 ° F.) using rather harsh conditions. Thereafter, the entire reactor effluent exits line 41 and enters stripper 43, where again the gaseous component of the reaction product of the second hydrogenation stage is separated from the liquid component and is passed from second stripper 47 to line 45.
Spills through. These gaseous components include, among others, hydrogen sulfide and ammonia. The liquid bottoms obtained from the stripper 43 in line 49 contain only about 1% of aromatic carbon, which is sent by line 51 and mixed with hydrogen in line 53, as a final step. Hydrogenation is performed in stage 3, ie the less severe final hydrogenation of stage 3 is performed in hydrogenation tower 55.

In the final step, the less severe hydrogenation of stage 3 carried out in the third hydrogenation tower, ie, hydrotreating tower 55, comprises a Group VIIIA metal component such as platinum, palladium or nickel (preferably Is 2000-3000 psig (preferably 2 psig) in the presence of a hydrogenation catalyst containing platinum (a form commonly used in reforming reactions).
500-3000 psig) hydrogen partial pressure and about 375
It is carried out at a temperature of -600F (preferably 450-550F).

In all of these reactions, the use of relatively high hydrogen partial pressures and relatively low temperatures hastened the performance of the hydrogenation without undue cracking of the liquid stream to undesired low boiling range materials, It is noteworthy that the aromatic component of the liquid stream provides a reduced desired reaction product.

In the illustrated embodiment, the liquid bottom draw in line 57 contains only about 0.3% or less aromatics by weight, and this trace amount of aromatic hydrocarbons is food grade. It will be satisfactory as white mineral oil.
In particular, polynuclear aromatic hydrocarbons will account for less than 30 ppm of the final food grade white mineral oil.

In operation, the naphthenic distillate, the initial feedstock, is fed to and mixed with the incoming desired partial pressure of hydrogen and hydrogenation is carried out in stage 1. Similarly, the gaseous component is separated from the liquid component in the stripper, whereby the gas exits as overhead stream in line 29 and the bottoms exits as liquid stream 33, and flows into line 3 in FIG.
5 to the second stage, namely the hydrotreating tower 37. Again, the mixing of the high partial pressure hydrogen with the liquid component causes a direct reaction with the appropriate catalyst at elevated temperatures, and
This leads to a reduction in the aromatic carbon in it. After separating the gas component and flowing it to the top line 45, the liquid bottom extraction oil 49
Is supplied to the third hydrogenation stage 55, although its aromatic carbon has been reduced. At the entrance of the third stage, it is mixed with the desired high partial pressure of hydrogen and the hydrogenation reaction is carried out in the third hydrotreating tower 55. The result is that the end product exits the bottom effluent line 57.

From the foregoing, it can be seen that the desired food grade white mineral oil is produced in line 57 by a method that is substantially different from conventional techniques for producing food grade white mineral oil.

Although the present invention has been described in some detail, this description is merely an example, which does not depart from the spirit and scope of the present invention (for which reference is made to the appended claims). It will be understood that the combination and rearrangement of the parts is possible.

[Brief description of the drawings]

FIG. 1 is a flow diagram showing a conventional method for producing food-grade white mineral oil.

FIG. 2 is a flow diagram illustrating a method for producing food grade white mineral oil according to the present invention.

[Description of Signs] 17 Adsorption tower 21 Hydrogenation tower 23 Naphthenic distillate supply line 25, 39, 53 Hydrogen supply line 31, 43 Stripper 37 Second hydrogenation tower 55 Third hydrogenation tower 57 Bottom effluent line

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-56-100896 (JP, A) JP-A-48-11302 (JP, A) JP-A-58-109592 (JP, A) 13418 (JP, B1) US Pat. No. 3,629,096 (US, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C10G 65/08 C10G 45/44

Claims (8)

(57) [Claims] (I) subjecting a naphthenic feedstock containing at least 15% by weight of aromatic carbon to a three-stage hydrogenation step; (ii) a first-stage hydrogenation step of 288 ° C. to 399 ° C.
(550 ° F. to 750 ° F.) and at 8.
2MPa gauge (1200PSIG) or more, but 1
Carried out at a hydrogen partial pressure of less than 3.7 MPa gauge (2000 PSIG); (iii) the feed to the second step consists of the liquid product from the first step; 329 ° C to 371 ° C
(625 ° F. to 700 ° F.) and 1
Carried out at a hydrogen partial pressure greater than or equal to 9.0 MPa gauge (2750 PSIG) but less than 20.7 MPa gauge (3000 PSIG); (v) the feed to the third step comprises the liquid product from the second step A process for producing food-grade white mineral oil from said naphthenic feedstock in a continuous process without solvent extraction or acid treatment and without hydrocracking. (A) reducing the aromatics content in the feedstock by 50% in a first hydrogenation step; and (b) separating gaseous components from the hydrogenated liquid product from step (a). (C) reducing the aromatic carbon content of the liquid product from step (a) to 1% by separating the gaseous component from the liquid product and subjecting the product to a second hydrogenation step (D) separating the gaseous product component of the hydrogenation product of step (c), and (e) separating the liquid product from step (c) and the gaseous component therefrom after steps (a) and By subjecting the final hydrogenation step to less harsh conditions than (b),
2. The process of claim 1 wherein a food grade quality white mineral oil containing only trace amounts of aromatics is produced. 3. The process according to claim 1, wherein the feed is a naphthenic or cycloparaffinic distillate containing aromatic carbon in the range of 15-25% by weight. 4. The method according to claim 3, wherein the first hydrogenation is performed with a nickel molybdenum catalyst and the gaseous component of the hydrogenated product comprises ammonia and hydrogen sulfide separated by stripping. the method of. 5. The method according to claim 1, wherein the first hydrogenation is performed in 10.3-12.
The method of claim 3 or 4, wherein the method is performed at a hydrogen partial pressure in the range of 1500-1800 PSIG and a temperature in the range of 650-700 ° F. 6. The second hydrogenation is performed with a nickel molybdenum catalyst, and the gaseous component of the second hydrogenated product comprises ammonia and hydrogen sulfide separated by stripping. 6. The method according to any one of 2 to 5. 7. The method of claim 2, wherein said relatively less severe final hydrogenation is performed in the presence of a platinum reforming catalyst.
One of the six methods. 8. The relatively non-severe final hydrogenation is performed at 2500-3000 PSI.
G) hydrogen partial pressure in the range and 232-288 ° C. (450
The method of claim 7, wherein the method is performed at a temperature in the range of -550 ° F).