US2921896A - Petroleum refining - Google Patents

Description

Jan. 19, 1960 J. L. JEZL 2,921,896

' PETROLEUM REFINING Filed Dec. 13, 1954 2 Sheets-Sheet 1 .Cuusiic u 29 Aikunol Solution K Alkanol Charge Oil \l Containing 2 33 Nonhydrocurbons /3o stripping Tower 34 Treating A d Z ne I? IZ P I 38 Water F] I I4 Solvent 3'! 39 15 Separator f i 4i 44 6 Oil AqueofiISnli v QD/i? f Stripping \20 Tower 2 Treating 3 Zone I8 45 Nonhydrocorbons I Alkanol I 26*: 3 GOUSTIC 27 35 Alkoml Stripping Tower 22 2! Refined Oil 24 INVENTOR.

JAMES L. JEZL Whiz), spew ATTORNEY 6 J. L. JEZL 2,921,896

PETROLEUM REFINING Filed Dec. 13, 1954 2 Sheets-Sheet 2 Untreated Petroleum Containing Nonhydrocorbon Constituents 5O Hydrogenation Acid and Extraction Solis and Treated Petroleum INVENTOR JAMES L. JEZL ATTORNEY United States Patent PETROLEUM REFINING James L. Jezl, Swarthmore, Pa., assignor to Sun Oil Company, Philadelphia, Pa., a corporation of New Jersey Application December 13, 1954, Serial No. 474,882

11 Claims. (Cl. 208-212) This invention relates to petroleum refining, and more particularly to the removal of nonhydrocarbon constituents from petroleum.

An increasingly great problem in the refining of petroleum is the handling of crudes and fractions having relatively high concentrations of nonhydrocarbons such as organic nitrogen, oxygen, and sulfur compounds. In many instances, it is desirable to remove such compounds without removing substantial quantities of hydrocarbon constitutents of the petroleum material. Prior to the present invention, this result has been difl'icult or impossible to achieve in a satisfactory manner.

According to the present invention, objectionable nonhydrocarbon constituents of petroleum are selectively removed therefrom in an economical manner which avoids various disadvantages of prior art operation. This is accomplished by contacting the petroleum charge material with an acid having ionization constant at 25 C. of at least about 1 1O- in the presence of a compound having less than five carbon atoms and selected from the group consisting of alkanols and saturated aliphatic ketones, the amount of acid on the anhydrous basis being at least 0.01 part by volume per 100 parts of charge but not greater than 4 parts per 100 parts of charge. The amount of acid on the anhydrous basisis preferably at least about 0.01 part by volume per 100 parts of alkanol, and not greater than 41') parts per 100 parts of alkanol. Preferred proportions are the following:

Parts by volume Petroleum charge 50 to 90 Alkanol or ketone 7.5 to 47.5 Acid 0.005 to 3.6

The treatment according to'the invention may be car- 2 the reaction products so that the latter may be effectively removed from the charge.

The alkanol or ketone employed according to the invention is one having less than five carbon atoms, and preferably less than four carbon atoms. The higher alkanols and ketones are unsuitable because of their too great solubility in oil under the conditions employed according to the invention. The suitable alkanols are methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, secondary butanol, and tertiary butanol. The suitable ketones are acetone and methyl ethyl ketone. Methanol is a preferred alkanol for use according to the invention, and acetone a preferred ketone. I v The process of the present invention may be applied to any suitable petroleum charge stock, e.g. crude petroleum, reduced crude, lubricatingoil distillates, fuel fractions, etc. The process is particularly advantageously applied to charge stocks' containing basic nitrogen compounds, though charge stocks containing other nonhydrocarbons of the types commonly occurring in petroleum are also advantageously treated according to the invention. Preferably, the charge stock is one which has not previously been'acid treated or solvent refined. However, the process of the invention has been found to be particularly beneficial in further improving the color of charge stocks which have previously been treated with hydrogen for purposes 'of color improvement. Thus, for example, a naphthenicbase lubricating oil maybe hydrotreated at 450- 575 F. and 10 35 atmospheres, with a space rate of 1 to 5 volumes of oil per volume of catalyst per hour, using a fixed bed of granular hydrogen treating catalyst of the type disclosed in Patent No. 2,654,696 issued October 6, 1953 to Walter N. LaPorte, and then further treated with a strong acid and an alkanol according to the invention.

In one embodiment, the present invention contemplates contacting a char ge stock first with acid and alkanol or ketone as described, in order to react basic nonhydrocarbon constituents with acid, and then with, a strong base and alkanol orketone in order to react acidic nonhydrocarbonconstituents with the base. The resulting alkanol or ketone solutions can be combined and further treated in an advantageous manner which is subsequently more fully described.

The invention will be furtherdescribed withreference I to. the attached drawing, wherein Figure 1 illustrates ried out under anhydrous conditions or in the presence of small amounts of water, not exceeding 20 parts .by volume per 100 parts of alkanol, and preferably not exceeding 5 parts per 100 parts of alkanol/ Suitable acids for use according to the inventioninclude benzene sulfonic acid, bromoacetic acid, alphabromopropionic acid, chloroacetic acid, alpha-chloropropionic acid,furnaric acid, hydrochloric acid, oxalic acid, phosphoric acid, phosphorous acid, phthalic acid, salicyclic acid, sulfuric acid, sulfurous acid, tartaric acid, thiosul furic acid, toluene sulfonic acid and trichloroacetic'acid, etc. Some acid anhydrides can be used also, e.g. sulfur dioxide. Sulfur trioxide would be unsatisfactory in most cases, however, because of its tendency to sulfate the alkanol employed.

' It has been found that the treatment according to' the invention substantially improves the color and oxidation stability of the petroleum charge material treated. It is believed that this improvement results chiefly from reaction of the acid treating agent with nonhydrocarbons which are basic in reaction, and extraction 'of the re action products from the charge by means of the alkanol or ketone. An important function of the alkanol or ketone is believed to be the prevention of hydrolysis of schematically one manner in which the process of the invention can be carried out, and wherein Figure 2 illustrates schematically a further particular embodiment-of the process of the invention. Referring to Figure 1, a charge oil containing small amounts of organic nonhy drocarbon. materials, such as organic nitrogen, sulfur, or

oxygencompounds, is introduced through lin e 11 into treatingz one 10. .A strong. acid, e.g. 93% sulfuric acid,

is introduced through . lines 12 and 13 into treating zone,

10, and an :alkanol, eg. anhydrous methanol, is introduced through lines 14 and 13 into treating zone,10, wherein the. charge oil is intimately contacted with the acidand alkanol. The acid is mixed with the alkanol prior to contacting acid and oil, in order to avoid discoloring of the, oil bycontact with the acid. The various rates of introduction may be such as to provide, for example, 33

parts by volume of methanol per parts of oil about 0.15 part of acid per 1100 parts of oil.

The oil then passes into alower' portion of treating zone 10 wherein it is washed with methanol introduced through line-15 in order to remove sulfuric acid which became incorporated in theoil during the contacting at and the higher level. 1 Treated 'oil containing small amounts; of dissolved methanol is removed from treating zone '10" through line 16. The treated oil has been'largelyfreed 39. The nonhydrocarbon residue. is 1'emovejd;;;th ne 4.5-.-.

of'organic nonhydrocarbon constituents which are basic in reaction. The treated oil may therr be introduced through lin 17 intotreating zone 20,.wherein it is contacted with methanol introduced throughline "18 and with a strong base, e.g. 50 B. caustic soda, introduced'through lines 19 and '18. The various rates of introductionjmayfbe. those which are commonlyused in treatmentsf of petroleum materials with alkaline alcoholic treating agents for removal of materials acidic in reaction. The oil .is washed in'a'lower portion. of treating zone 20 with methanol introduced through line 21. Treated oil, substantially free of organic nonhydrocarbon constituents which are acidic or basic in reaction, is removed from treating zone 20 through line-22.

If desired, treatedoil from zone 10 may be bypassed through line 23 around zone 20, thuseliminating for the bypassed material the treatment with alcoholic alkaline material. i N e 'Treated oil is passed through'line 24into stripping tower 25 'wherein'methanol is stripped from the oil and recycled through lines 26 and 27 to the various points of introduction of methanol into the treating steps. 1 Refined coil is removed from stripping tower 25 through line 28. y Y

. 'Ihernethanol phase is removed from zone 10 through line '29. This phasefcontains reaction products, e.'g. salts of sulfuric acid with basicnonhydrocarbondorlstituents of the charge. Some oil, neutral organic non hydrocarbon materials and residual sulfuric acidfare generally contained in this phase. f

' The methanol phase is removed from zone 20'through line 30. This phase contains reaction products of sodium hydroxidewith acidic nonhydrocarbon constituents of the charge, and also generally some residual sodium hydroxide. V I I v The two methanol phases are combined and contacted with caustic soda introduced through line 31 in order to hydrolyze reaction products of nonhydrocarbons with sulfuric acid. It is to be understood that,t hi sintroduc tion of caustic soda would be unnecessary infthej case. where sufiicient free alkali was provided by "the"alk anol phase introduced through line 30.

The methanol containing basic nonhydrocarbons and re-: action products of 'acidic nonhydrocarbons alkaliis introduced through line 32 into stripping tower 33, where in alkanol is stripped from thenonhydrocarbonfreaction products and recycled through'line's 34,35 and 27 to the various points of introduction of methanol into the treatingsteps. Excess water can be removed from the meth-' anol by distillation if necessaryr Make-up mcthan'olis added to the system through line 36 as needed. V v

Thenonhydrocarbon reaction product residue from the stripping operation is removedfrom tower 33 th'rou gh line 37', Water is added through line 38;if necessary, in'order to dissolve any salt which may besuspended' in' the residue. The resulting material maythen be extracted with aqueous isopropanol andnaphtha 'in order t n-.-; 1

cover alkali metal salts of' acidic 'nonhydrocarbons in 'the;

isopropanol layer and basic nonhydrocarbons in the naphthalaye'r. y e 1 In the case'where treating zone 20 has been bypassed, and line 30 is closed, the residue from stripping tower' 33' is mainly basic nonhydrocarbon materialscontainin'gsuspended salt. After addition of water, is necessary, these materials are admixed with a hydrocarbon solvent,

e.g. naphtha, introduced through line 39, and thenipassed; into separator .40, wherein an aqueous inorganic salti'phase. is separated and removed through line 41. -Thehydrocarbon phase is removed through line 42; and introduced into stripping tower 43, wherein solvent is,strippedlfr'rom v the nonhydrocarbons and recycled throughlines' IA-sand s-aqs r ins o, the prcj ntlinvenfibmithe ram of, aid.

oughv used should be not greater than 4 parts per 100 parts 0 oil. If greater amounts are used, the amount of salt formed upon addition of caustic through line 31 is excessive, and the stripping of alkanol in tower 33 cannot be effected without disadvantageous effects from the salt unless a rather large amount of water is added prior to the stripping operation.

Referring to Figure 2 previously untreated petroleum,

i such as a lubricatingoil fraction which contains nonhy- This-example shows that-the addition of only 0.145 part drocarbon constituents,.is introduced into hydrogenation zone 50 through line 52 ,Qand is hydrogenated therein according to the procedure" described previously. The hydrogenated oil-is then introduced through line 53 into extraction zone 51-, wherein it is contacted with sulfuric acid and methanol introduced through line 54. The contacting in the extraction zone is generally similar to that described previously with respect to Figure 1. A methanol solutionof salts of. sulfuric acid with basic cdnstit'uents of the. hydrogenated lubricating oil is withdrawnthfou'gh line 55; and the treated petroleum is withdrawnthrough line 56. e v

T 6. following examples illustrate the invention:

, y ....Example I f A' lubricating oil' distillate from reduced naphthenic base crude 'w reated'with about 33 partsby volume of substantially nhydrous methanol per IGO'parts of oil and with"l"pou'nd'of 93 sulfuric acid per barrel of oil (0.145 partby volume of H 50 per '100 parts of oil), the methanolfa'nd' sulfric acid having been previously mixed'and the" mixturdcontacted at room temperature with-the oilunder agitation conditions for 'a period of about 20minut'sf" The layers were then separated and the oilwashed several times with fresh alcohol in the absence of added sulfuric acid. The' small amount of methanol remaining'inj the oil was evaporated under Vacuutmf- For comparison, another portion of the same distillate treated with about 33 'partsby volume of methanol per IOO'parts ofloil infthe absence of sulfuric acid. The oxidation stabilitie's of the respective treated oils were determined by obscrving'theiinduction period of the oils at 230 i.e.'the time el'apsingywhile the oils were in contactj'with' anjoxidiz'in'gmedium at that temperature, before a predeterminedsmall amount of oxidation of the oil sample occurred. Thefollowing table shows the oxidation stability of the oil prior to treatment and after the respective treatments:

I Oxidation stabilityHrs.

Untreated oil 3.33 Oil treated with methanol alone 3.37 ti tet 'w h s h'si a a 2 04 of H 804, to 33'parts of methanol produces a very great increase in thestabilizing capacity of the treating mate -i-a1 1 g zaxa plal fern: ulsar riiefsani gcner'al kind as those described in Example I-were performed on various charge oils'iufsing varying'aniounts of sulfuric acid. The following,'table;shows theresults,-.including those given in ExplefI. '1. In each case, 33 parts ofmethanol per parts; of'oil were used; i 1 Z I g Parts Oxidation Stability W I HiSOlPQI. i Oharge Btockloo-Parts a -i 011, Untreated CHiOH GHaOH I Oil Alone H1504 3.33 i 3.37 7.00 3.33 v 3.37 6.53 3.33 3.37 6.72 3.48 4.63 4. 98 3.10 3.28' 4.78 3.53 4.15s 6.73

asst-peer Parts N PA Color 2804 Per Charge Stock 100 Parts Oil Untreated OHQOH CH3OH- Oil Alone H280;

. 25 1 O. 145 3+ 2%: E 0. 145 2V 2%+ 2- This table shows was obtained by to the methanol. ularly notable in stock B.

The effect of treatment according to the invention on nitrogen content of a charge stock was shown in an experiment similar to the one described above on charge stock D. In this experiment; the total nitrogen content (Kjeldahl) of the charge was reduced from 0.038 per cent to 0.008 percent by treatment with methanol and sulfuric acid, and the treatment reduced the basic nitrogen content, as determined by anhydrous titration with perchloric acid, from 0.024 percent to 0.001 percent.

The treatment according to the present invention is advantageous in that entirely satisfactory products can be obtained, if desired, without clay treating or the like following the treatment according to the present invention. By way of contrast, in processes where larger amounts of strong acid such as sulfuric acid are employed, clay treating or the like is generally required in order to obtam a satisfactory product. As mentioned previously, not substantially more than 4 parts by volume of acid per 100 parts of charge are employed, and preferably the amount does not substantially exceed 1 part per 100 parts of charge.

that in all cases improvement in color adding small amounts of sulfuric acid The improvement in color was particthe case of the .hydrotreated charge Example III An experiment generally similar to those described 1n Example II was performed using acetone containing about volume percent of water in place of the substantially anhydrous methanol of Example II. Improvement in color approximately as great as the corresponding improvement obtained in Example II resulted. Satisfactory separation of acetone from oil was obtained. Generally, the water content of a ketone employed, not admixed with alkanol, according to the invention will be in the approximate range from 2 to 20 volume percent, preferably 2 to 10 volume percent.

Example IV An experiment generally similar to those described in Example II was performed using isopropanol containing about 10 volume percent of water in place of methanol. Improvement in color approximately as great as the corresponding improvement obtained in Example 11 resulted. Satisfactory separation of isopropanol from oil was obtained. Generally, the Water content of ethanol or higher alkanol employed, not admixed with methanol will be in the approximate range from 2 to 20 volume percent, preferably 2 to 10 volume percent.

Example V ;An experiment generally similar to those described in Example H was performed using a mixture' of equal volumes of substantially anhydrous methanol and substantially anhydrous acetone in place of themethanol em ployed in Example II. The results were superior to the corresponding results obtained in Example II, in that better color and better layer separation were obtained in the case'of the methanol-acetone mixture. Preferably, the amount of ketone in a ketone-alkanol mixture employed according to the invention is in the range from 25 to volume percent. In the case of mixtures not containing methanol, 2 to 20 volume percent of water may be needed for satisfactory layer separation.

Example VI An experiment generally similar to those described in Example II was performed using a mixture of equal volumes of substantially anhydrous methanol and substantially anhydrous isopropanol in place of the methanol employed in Example II. The results were superior to those'obtained in Example II, in that better color and better layer-separation were obtained in the case of the methanol-isopropanol mixture. Preferably, the animator methanol in a mixture of methanol and a higher" alkanol or alkanols employed according to the invention is in the rauge from 25 to 75 volume percent.

The process according to the invention is advantage ously adapted to the preparation of charge stocks for use in catalyticcra'cking of petroleum hydrocarbon materials The removal of nonhydrocarbon materials 'by the process according to the invention produces a superior charge stock for such catalytic cracking operations. The latter may be any of the well-known catalytic cracking. processes of the prior art, e.g. those involving the use of synthetic silica-alumina cracking catalyst, activated cllay catalyst, etc.

The invention claimed is:

1. Process for refining petroleum which comprises: contacting previously untreated petroleum containing basic nonhydrocarbon materials with a compound having less than 5 carbon atoms and selected from the group consisting of alkanols having the formula ROH where R is an alkyl hydrocarbon radical and saturated aliphatic ketones, in the presence of 0.01 to 40 volume percent, based on said compound, of an acid having ionization constant at 25 C. of at least about lxl0- said petro leum being in contact with said compound during the entire period of contacting of said petroleum with said acid, the amount of acid on the anhydrous basis being at least about 0.01 part by volume per parts of petroleum but not greater than about 4 parts per 100 parts; of petroleum, and the amount of water present being not; greater than about 20 parts per 100 parts of said com pound; and separating petroleum in liquid phase from, said compound in liquid phase.

2. Process for refining petroleum which comprisesz; contacting previously untreated petroleum containing; basic nonhydrocarbon materials with methanol in they presence of 0.01 to 40 volume percent, based on meth--. anol, of sulfuric acid, the amount of acid on the anhy--- drous basis being at least about 0.01 part by volume per 100 parts of petroleum but not greater than about 4; parts per 100 parts of petroleum, and the amount of water present being not greater than about 20 parts per 100 parts of alkanol; said petroleum being in contact with; said methanol during the entire period of contacting of said petroleum with said acid separating the petroleumfrom the methanol; contacting the separated petroleumv with methanol in the presence of caustic soda, thereby to react caustic soda with acidic constituents of the petroleum; separating the petroleum from the methanol;: combining the methanol portions separated respectively in the two separating steps recited; and recovering non V ketone .as defined.

hydrocarbon constituents of the combined methanol portions.

3. Process according to claim 1 wherein petroleum is contacted with a mixture of an alkanol as definedand a 4. Process according to claim. 1 wherein petroleum is contacted with a mixture of methanol and a higher alkanol.

'5. Process according to claim 1 wherein said compound is methanol.

6. Process according to claim sulfuric acid.

7. Process according to claim 1 wherein said acid is hydrochloric acid.

8. Process according to claim 1 wherein petroleum is subsequently separated from a mixture of said compound and salts of said acid with basic nonhydrocarbon constituents of v the petroleum, a strong base is added to said mixture thereby to form saltso'f said acid and said base and liberate saidbasi'c nonhydrocarbon constituents, said compound is distilled from the resulting mixture, and basic nonhydrocarbon constituents in the distillation residue are separated from said salts.

9. Process according to claim 2 wherein methanol is distilled from the combined methanol portions, water is added to the distillation residue to dissolve sodium sul- 1 wherein said acid is fate, and sodium salts of said acidic constituents of the 5755".1'1. and a pressure withintlie approximate range fromlO to .35 atmospheres in the. presence of a granular hydrogen-treating catalyst; and contacting the resulting petroleum. containing, basic nonhydrocarbon materials with a compound havingless than '5 carbon atoms and selected from the group consisting of alkanols having the 7 petroleum with said acid, the amount of acid on the petroleum are separated from basicnonhydrocarbon constituents of the petroleum.

10. Process according to claim 1. wherein the ainount' of saidc'ompound is at. least 7.5 parts per volume per 90 parts of said petroleum.

11. Process for re'fining petroleum which comprisesjz hydrogenatingfpreviously untreated petroleum at a tem perature within the approximate range from 450 F. to

anhydrous basis being at least about 0.01 part by volume per 100 parts of pertoleum but not greater than about 4 parts per 100 parts of petroleum, and the amount of water present being not greater than about 20 parts per 100 parts of said compound; and separating petroleum in liquid phase from said compound in liquid phase.

References Cited in the file of this patent UNITED STATES PATENTS Shoualter July 17, 1956

Claims (2)

1. PROCESS FOR REFINING PETROLEUM WHICH COMPRISES: CONTACTING PREVIOUSLY UNTREATED PETROLEUM CONTAINING BASIC NONHYDROCARBON MATERIALS WITH A COMPOUND HAVING LESS THAN 5 CARBON ATOMS AND SELECTED FROM THE GROUP CONSISTING OF ALKANOLS HAVING THE FORMULA ROH WHERE R IS AN ALKYL HYDROCARBON RADICAL AND SATURATED ALIPHATIC KETONES, IN THE PRESENCE OF 0.01 TO 40 VOLUME PERCENT, BASED ON SAID COMPOUND, OF AN ACID HAVING IONIZATION CONSTANT AT 25*C. OF AT LEAST ABOUT 1X10**-3, SAID PETROLEUM BEING IN CONTACT WITH SAID COMPOUND DURING THE ENTIRE PERIOD OF CONTACTING OF SAID PETROLEUM WITH SAID ACID, THE AMOUNT OF ACID ON THE ANHYDROUS BASIS BEING AT LEAST ABOUT 0.01 PART BY VOLUME PER 100 PARTS OF PETROLEUM BUT NOT GREATER THAN ABOUT 4 PARTS PER 100 PARTS OF PETROLEUM, AND THE AMOUNT OF WATER PRESENT BEING NOT GREATER THAN ABOUT 20 PARTS PER 100 PARTS OF SAID COMPOUND, AND SEPARATING PETROLEUM IN LIQUID PHASE FROM SAID COMPOUND IN LIQUID PHASE.

11. PROCESS FOR REFINING PETROLEUM WHICH COMPRISES: HYDROGENATING PREVIOUSLY UNTREATED PETROLEUM AT A TEMPERATURE WITHIN THE APPROXIMATE RANGE FROM 450*F. TO 575*F. AND A PRESSURE WITHIN THE APPROXIMATE RANGE FROM 10 TO 35 ATMOSPHERES IN THE PRESENCE OF A GRANULAR HYDROGEN TREATING CATALYST, AND CONTACTING THE RESULTING PETROLEUM CONTAINING BASIC NONHYDROCARBON MATERIALS WITH A COMPOUND HAVING LESS THAN 5 CARBON ATOMS AND SELECTED FROM THE GROUP CONSISTING OF ALKANOLS HAVING THE FORMULA ROH WHERE R IS AN ALKYL HYDROCARBON RADICAL AND SATURATED ALIPHATIC KETONES, IN THE PRESENCE OF 0.01 TO 40 VOLUME PERCENT, BASED ON SAID COMPOUND, OF AN ACID HAVING IONIZATION CONSTANT AT 25*C. OF AT LEAST ABOUT 1X10**-3, SAID PETROLEUM BEING IN CONTACT WITH SAID COMPOUND DURING THE ENTIRE PERIOD OF CONTACTING OF SAID PETROLEUM WITH SAID ACID, THE AMOUNT OF ACID ON THE ANHYDROUS BASIS BEING AT LEAST ABOUT 0.01 PART BY VOLUME PER 100 PARTS OF PETROLEUM BUT NOT GREATER THAN ABOUT 4 PARTS PER 100 PARTS PETROLEUM, AND THE AMOUNT OF WATER PRESENT BEING NOT GREATER THAN ABOUT 20 PARTS PER 100 PARTS OF SAID COMPOUND, AND SEPARATING PETROLEUM IN LIQUID PHASE FROM SAID COMPOUND IN LIQUID PHASE.

Images