CA1085334A - Simultaneous deasphalting-extraction process - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

An asphalt containing mineral oil is simultaneously deasphalted and extracted by contacting the oil with a deasphalting-extraction solvent comprising a light hydrocarbon and N-methyl-2-pyrrolidone containing from 0-5 LV% water.

Description

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CKGROUND OF THE INVENTION
~ Field of the Invention 3 This invention relates to a process for simul-4 taneously deasphalting and extracting an asphalt containing mineral oil. More specifically, this invPntion is a process 6 for simultaneous solvent deasphalting-extracting a mineral 7 oil containing asphaltic and aromatic components which com-8 prises contacting said oil with a solvent comprising a mix-g ture of a light hydrocarbon and N-methyl-2-pyrrolidone (here-inafter referred to as NMP for the sake of brevity). Still ll more particularly, the present invention is a simultaneous l2 solvent deasphalting-extraction process for a petroleum oil 13 containing asphaltic and aromatic components which comprises 14 contacting the oil with a solvent comprising a mixture of lS (a) liquid, low molecular weight C2-Clo carbon atom hydro-16 carbons and their mixtures and (b) NMP containing from about 17 0-5 LV7. water.
18 Description of the Prior Art 19 It is well known to those skilled in the art to deasphalt asphalt-containing mineral oils with light or low 21 molecular weight hydrocarbons such as propane, especially in 22 the preparation of lubricating oils from resids and crude 23 oils. In such a process, an oil feedstock or stream contain-24 ing asphaltic type constituents is mixed with a light hydro-carbon, such as liquid propane, under temperature and 26 pressure conditions whereby the asphaltic type constituents 27 are precipitated. After separation of the asphaltic type 28 constituents from the deasphalted oil, the respective streams ~ are handled in well known manners in order to recover the solvent. It is also well known to those skilled in the art 31 to treat certain types of oil feedstocks, particularly dis-32 tillate lube oil feedstocks, with various solvents in order

- 2 -, 1 to separate the relatively more aromatic and polar type con-2 stituents having low VI, from the relatively more paraffinic

3- type constituents having high VI. The more commonly employed

4 extraction solvents useful in such processes include phenol, various cresols,lfurfural, sulfur dioxide, and more recently, 6 solvents such as NMP along with minor amounts of water. In ~ ~`
7 such extraction operations the oil is contacted with a sol-8 vent such as phenol, containing minor amounts of water, 9 either in a countercurrent treating operation or in a multi-stage batch operation under temperature and pressure condi-11 tions designed to secure phase separation. As a matter of 12 practice, the oil to be treated is usually introduced into 13 one end of a countercurrent treating zone while a solvent or 14 solvent mixture is introduced at the other end. The solvent and oil flow countercurrently under temperature and pressure l6 conditions to produce a raffinate phase and an extract phase.
17 The solvent rich extract phase is withdrawn from one end of 18 the countercurrent treating zone and contains most of the 19 aromatic and polar components of relatively low VI, while the oily or solvent poor raffinate phase, containing the more 21 paraffinic, high VI type constituents is withdrawn from the 22 other end of the treating zone. The respective streams are 23 then handled in well known manners to separate and recover 24 the solvent-Another process well known to those skilled in 26 the art is the Duo-Sol process for the extraction of high Vl, 27 light color, low carbon residue lube base stocks from either 28 residual or distillate lube feeds. This is a simultaneous deasphalting-extraction process which derives its name from ~ the use of two solvents. The solvents employed are propane ~ -31 and a blend of cresol and phenol. The propane preferentislly 32 dissolves a relatively high VI, paraffinic type of lube base .. , - , . . , . . ~, , . . .

- I lV8S334 stock from the feed, while the cresol and phenol preferen-~ tially dissolve the asphalt, undesirable aromatics, polars 3 and colo~ bodies rom same as an extract. The combination 4 lu~e process disclosed in U.S. Pa~ent ~c 3,291,718 incor~
s porates a Duo-Sol Ixtraction deasphalting operation, wherein 6 a suitable feed.such:as.an.atmospheric resid is fed into the ., ``-7 mi.ddle o a deasphalting-extraction zone, while propane is --. 8 fed into the bottom and phenol is fed into the top to pro-9 duce a deasphalted raffinate phase rela~ively low in aro-o matics and polars and from which useful, high VI lube oils 11 are made- NMP ~as recently been suggested as useul for 12 deasphalting and or simultaneous deasphalting~solvent 13 refining. In U.S. Patent No. 3~779~895J NMP is 6uggested as being a member of a group o solvents consisting of low - :
,~ moleculsr wei.gllt parafins contain:;ng 3~10 c~rbon atoms, NMP
16 and furfural, for deasphalting aqueous dispersions of heavy 17 petroleum fractions which have been pretreated with high ~ 18 tempera~ure ~team. Finally, in U.S. Patent Nos. 3,779,896 ; 19 and 3,816,295, lube oils are prepared by subjecting a ::: 20 residuum-containing petroleum fraction to simultaneous , 21. deasphalting-solvent refining using either urfural or NMP
22 as the combinfltion deasphalting-solvent reining solvent and 23 most preferably NMP, because of its greater thermal stablli~y 24 and ~olvent capacity.
25 Because the prior art discloses NMP as being 26 potentially useful both for deasphalting and for simultaneous . 27 deasphalting-solvent refining or extrsction, and because it 2B discloses N~P as a member o a group o solvents consisting 29 o.C3-C10 carbon atom parafins and furfural (U.S. Patent No. 3~779,895~, but nowhere suggests mixing NMP wi~h a lower 31 molecular weight hydrocarbon ~or simultaneou~ly densphaltin~-32 ~olvent ~efining, one could reasonably and logically conclude l that such a process had been tried and found to be unsatis-factory.

4 It has now been discovered that one can sirnultane-

5 ously solvent deasphalt and solvent extract a mineral oil

6 feed containing asphaltic and aromatic components by a

7 process which comprises contacting said oil with a solvent

8 comprising a mixture of (a) liquid, low molecular weigh~ -~

9 C2-C10 carbon atom hydrocarbons and their mixtures and (b) NMP containing from 0-5 LV (liquid volume) % water. When ll the oil is contacted with the solvent, two layers are 12 formed, an upper or raffinate layer and a lower or extract ;
13 layer. The upper layer contains most of the hydrocarbon 14 solvent along with the desired oil, while the lower layer contains most of the NMP and water along with the asphaltenes 16 and most of the aromatic and polar components of the feed.
17 The upper layer is w~thdrawn from the iower layer and each .... . .
18 layer is then further processed to recover the solvent. The 19 upper or raffinate layer containing the desired oil may be further processed either before or after removing the solvent 21 therefrom in order to hydrorefine, dewax, etc.
22 The combination deasphal~ing-extraction solvent 23 used in the instant invention comprises a liquid mixture of 24 (a) C~-Clo carbon atom hydrocarbons ranging from ethane or -ethylene to decane and mixtures thereof and (b) NMP contain-26 ing from 0-5 LV7, water. Minor amounts of other hydrocarbons 27 may be present in the solvent without substantially affecting ;
28 the overall efficiency of the process. Preferably, the hydro-carbon comprises low molecular weight paraffins containing 3-10 carbon atom~ and mixtures thereof and most preferably 3 31 carbon atom hydrocArbons such as propane. A particularly 32 preferred solvent ls a mixture of propane and NMP containing .

.,, lS1SS334 1 about 0-2 L~h water based on the NMP content thereof. The 2 volume ratio of the light, low molecular weight hydrocarbon 3 to the NMP will range from 2/1 to 6/1 depending upon the 4 hydrocarbon and the mineral oil feed. An illustrative but S non-limiting example is a mixture of (a) NMP containing 1 LV7.
6 water and (b) propane, wherein ~he volume ratio of propane 7 to NMP is 2.5/1. The amount of deasphalting-extraction sol-8 vent employed and the operating temperatures and pr~ssures 9 utilized must be controlled to suit the particular solvent lo composition used and the oil feedstock being treated in ll order to obtain a deasphalted~extracted oil of the desired 12 viscosity, aromatics content and Conradson Carbon resi.due 13 content. In general, the amount of light hydrocarbon used 14 will range from about 50 to 800 L~h of the feed, while the NMP with or without the presence o water will range from 50 16 to 400 L~7. of the feed. More preferably, the light hydrocaro 17 bon will range from 400 to 600 LV7. and the NMP from 150 to 18 250 L~/o of the feed. Particularly preferred solvents for 19 Middle East feedstocks include propane as the light hydro~
carbon solvent and NMP with 1 L~L water as the polar solvent.
2l Thus when using an Arab Light 600F~ resid as feedstock, the 22 propane treat will preferably be 500 L~!. and NMæ treat about 23 200 L~h. The contacting step takes place at a temperature 24 above about 50F, but below the temperature of complete mis-cibility of the feed in the solvent and below the critical 26 temperature of the light hydrocarbon. This temperature 27 generally ranges from about 70 to 350F, preferably from 28 about 120 to about 190F and at a pressure rangin~ from 29 about 10 to about 600 psig, and preferably from about 180 to about 500 psig. The exact conditions required will depend 31 of course upon the particular solvent used and solvent¦feed 32 ratio. Further, it i8 not absolutely necessary to the l aperation of this invention, but it is prefèrable for the 2 feed to be introduced into about the middle of the con~acting 3 zone (i.e., a deasphalting~extraction tower), the light hydro-4 carbon introduced at the bottom of said zone and the NMP with or without water introduced at the top thereof. This results 6 in countercurrent solvent and oil flow which, under proper 7 temperature and pressure condLtions, effects phase separation 8 to produce two liquid layers or phases, an upper layer or 9 raffinate containing most of the hydrocarbon solvent along lo with the desired oil, and a lower layer or extract containing 11 most of the NMP and water along with the asphaltenes and most 12 of the aromatic and polar constituents of the oil. The raf~
13 finate is withdrawn from the extract. The raffinate and 14 extract are then separately processed further to recover the solvent from the deasphalted oil and extract.
16 The process of the instant invention may be used 7 to simultaneously deasphalt~extract any mineral oil feedstock 18 containing both asphaltene and aromatic components. Sui~able 19 feedstocks include crude oils, atmospheric and vacuum residua, crude bottoms, and mixtures thereof having initial boiling 21 points ranging from about 500 to about 1100F (at atmospheric . ~. . .
22 pressure). Thus, both atmospheric residuum boiling above 23 about 700F and vacuum residu~m boiling above about 1050~F
24 can be treated by the process of the instant invention. Such ~ ~
25 feeds may come from Arabian, Light or Heavy crudes, Kuwait, -26 Venezuelan and Western Canadian crudes such as Cold Lake and 27 Athabasca bitumen, Bachaquero and the likeO Atmospheric and 28 vacuum resids from Aramco, Safaniya and Bachaquero are par-~ ticularly suitable feedstocks as well as synthetic feedstocks derived from Athabasca Tar Sands, etc. The contacting of the 3l feed with the deasphalting-extraction solvent may be carried 32 out in one or more mixer-settler units or in one or more . lOSS334 l countercurrent liquid~liquid contacting towers. In the 2 latter case, the feed enters the tower near the middle with 3 the light hydrocarbon solvent entering near the bottom and 4 the NMP with or without water entering near the top. The tower is provided with internals such as packing, staggered 6 rows of angled irons or liquid~;liquid contacting trays, etc.
7 to provide sufficient contacting of the solvent and feed.
8 The asphaltic or extract phase passes through the tower 9 countercurrently to the bulk of the rising stream of propane and leaves the bot.tom of the tower. The raffinate phase con-ll taining the desired deasphaltèd oil passes upward through 12 the tower countercurrently to the bulk of the downcoming NMP
and exits at the top of the tower.
14 DESCRIE~ ~
The invention will be more clearly understood by 16 reference to the following example.
l7 Example_l 18 In this example, pilot plant runs were made on an 9 Arabian Light atmospheric resid having an initial boiling point of 750P~ and an API gravity of 16. This feed was fed 2l into the middle of a solvent deasphalting-extraction tower, 22 with propane fed into the bottom of the tower and a polar 23 solvent selected from the group consLsting essentially of ~ 24 phenol, NMP or NMP containing 2 LV~b water wa5 fed into the i 25 top of the tower. The operating conditions in the tower 26 were a pressure of 500 psig and a temperature ranging between 27 about 131 and 162F, as shown in Table 1. This produced a 28 deasphalted oil raffinate and an asphaltic extract, the raf- -29 finate being removed from the top of the tower and the extract from the bottom. Solvent was removed from the 31 resulting raffinate and asphaltic extract with the properties 32 of the recovered, solvent~free deasphalted oil and asphalt 33 shown in Table 1.

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2 PILOT PLANT R~S USING PHENOL OR NMP IN
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5 POLAR SOLVENT PHENOL NMP 2 LVZo H~O

7 Pressure, psig ~ 500 8 Temperature, CF -9 Top of Tower 151 134 162 Bottom of Tower 131 125 140 12 Polar Solvent/Feed O.9tl 0.9/1 1.1/1 13 Propane/Feed 4.5/1 4.2/1 3.5/1 15 Yield, L~h 67 72 70 16 Gravity, API 24.7 24.6 24.6 17 Conradson Carbon, Wt.X 0.8 0.6 0.7 :
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19 Specific Gravity 1.07 1.10 1.09 Softening Point, F 120 154 130 21 (ASTM D 2398~71) ' ~ ~ .

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1 These results show that not only was less solvent 2 required using a propane/NMP solvent, but the yield of 3 deasphalted oil was unexpectedly greater than the yield 4 obtained using phenol, and further, the propane¦NMP produced S asphalt was harder. Therefore, valuable heavy lubes are not 6 lost to the asphalt as in the propane/p'nenol case.
7 Example 2 8 In this experimen~, the feed was a Light Arab 9 680F~ atmospheric resid which was treated on a batch basis using NMP and propanelNMP as the solvent for the simultane-11 ous deasphalting-extraction. The properties of the feed and 12 solvent-free, deasphalted oils are listed i~ Table 2. The 13 NMP deasphalting-extraction was accomplished using three 14 treats of 200 L~/o each (~asPd on the feed) for a total treat of 600 LV~/o NMP~ The deasphalting-extraction accomplished 16 using propanelNMP employed only one treat with a total sol-17 vent treat (propane plus NMP) of 550 LV~/~ based on the feed.

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- 10 - , I i~)85334 1 i TABLE 2 2 BATCH TREATMENT OF ARAB LIGHT 680F~ RESTDUI~

3 l Propane-4 SOLVENT I ~MP NMP

5 or~ATl~r CO~DlTICN5 - --6 Propane Treat, LV~/o -~~ 390 - 7 N~mber o Treatsj 3 8 Total NMP Treat, ~L~/o 600 1 160 9 Water Content of NMP, L~b 1 1.2 ..
Temperature, C 88 77 :

11 Pressure, psig 0 380 ;

12 Arab Light

13 E~l~lC~5LI IODa~LEllLE 360C~ Feed

14 Yield, L~/o 100 30 55 Density, kgldm3~15C 0.9530 0.9121 0.9095 , 16 Viscosity, cstl98.9C 24.3 ;~ 17 Refractive Index at 75C 1.5190 1.4890 ~ :
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1 The data in Table 2 show that a greater yield of 2 higher quality deasphalted oil was obtained using propane/
3 NMP compared to using NMP alone, even though the to,tal sol-4 vent treat and the number of treats were less.
Example 3 6 This experiment was similar to that in Example 2, 7 except that the feed was a 750F+ Arab Light resid which was 8 treated with N~ , propan~ and propane/NMP. The operating 9 parameters, feed properties and the properties of the solvent^
free, deasphalted oils are listed in Table 3. These data 11 show that treating with NMP alone gave'the lowest yield and 12 poorest quality of deasphalted oil~ Treating with propane 13 alone gave a high yield of good quality deasphalted oil, 14 while treating with propane/NMP gave the best quality of oil ~5 and from only one treat.

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1~)85334 Example 4 2 This experiment was similar to that in Example 3, 3 except that the feed was a heavier, 990F~ Arab Light resid.
4 The data for the feed and solvent-free deasphalted oils are listed in Table 4, showing that polar solvents become com-6 pletely unsuitable as the resid is cut deeper. Again, NMP
7 alone gave a low yield of extremely poor, black deasphalted . .
8 oil, while propane and propane/NMP gave higher yields o~ a q much superior, more highly refined oil. Further, the propane/
NMP solvent combination was far superior to propane alone 11 for the improvement of color as well as in the removal of 12 Conradson Carbon residue and sulfur.

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ExamPl e 5 2 This example demonstrates the usefulness of this 3 invention ~or removing aromatic componenes from the oil. In 4 this experiment an Arab Light 750Ft resid was simultaneously deasphalted and solvent extracted using both propane and 6 propane1NMP, with the NMP containing 2 L~/o H20. The 7 properties of the feed and the solvent-free deasphalted-8 extracted oils are listed in Table 5.
- 9 The data show that simultaneously deasphalting-0 extractin~ the feed with the propane/(NMP ~ 2 L~/o H20) sol-11 vent produced a raffinate oil with an aromatics content of 12 33 wt.% compared to the 46 wt.% aromatics content of the 11 feed.

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Claims (10)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR
PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for simultaneously solvent-deasphalting-extracting a mineral oil feedstock containing asphaltic and aromatic components which comprises:
(a) contacting said feedstock with a solvent comprising a mixture of (i) liquid, low molecular weight C2-C10 hydrocarbons, and mixtures thereof and (ii) NMP containing from 0-5 LV% water, said contacting resulting in the formation of two layers or phases, an upper or raffinate layer which contains most of the hydrocarbon solvent and the desired oil and a lower or extract layer which contains most of the NMP and water along with the asphaltenes and most of the aromatic and polar components of the feed;
(b) separating the raffinate from the extract layers;
(c) processing said raffinate and extract layers to recover the solvent, NMP and extracted deasphalted oil.

2. The process of claim 1 wherein said contacting step is conducted at a temperature ranging from about 70 to about 350°F, at a pressure ranging from about 10 to about 600 psig.

3. The process of claim 2 wherein said contacting step is conducted at a solvent-to-oil ratio ranging from about 50 to 800 LV% for the hydrocarbon and from about 50 to 400 LV% for the NMP.

4. The process of claim 3 wherein the mineral oil is a petroleum oil having an initial boiling point ranging from about 700 to about 1050°F
at atmospheric pressure.

5. The process of claim 4 wherein said oil is a resid having an initial boiling point ranging from about 400°F+ to about 1100°F+ at atmospheric pressure.

6. The process of claim 3 wherein the solvent consists essentially of a mixture of (a) propane and (b) NMP containing about 0-2 LV% water.

7. The process of claim 1 wherein the mineral oil feedstock is a heavy petroleum oil selected from the group of crude oils, atmospheric resids and vacuum resids containing both asphaltic and aromatic components.

8. The process of claim 7 wherein the contacting step is conducted at temperatures and pressures ranging from about 120 to 190°F and about 180 to 500 psig, respectively.

9. The process of claim 8 wherein the liquid hydrocarbon is present in an amount ranging from 2/1 to 6/1 parts by volume based on the NMP content of the solvent.

10. The process of claim 9 wherein the solvent is a mixture of propane and NMP and wherein the NMP contains from 0 to 2 LV% water.