US2937133A - Balanced gasoline from wide boiling naphtha - Google Patents

Description

y 1960 J. w. HERRMANN ETAL 2,937,133

BALANCED GASOLINE FROM WIDE BOILING NAPHTHA Filed Oct. 1, 1957 2 sheets-sheet 1 6 25 3 '1 2 r! I LL .i g Q 4! w n. 1 a v 6 m H 2 i J 2 2 L 5 w v 5 g I! I I 9 r g IL [L Q g 8 o B m U N N John W. Herrmclnh Donald D. MacLuren By I Attorney United States Paten O i BALANCED GASOLINE FROM WIDE BOILING NAPHTHA John W. Herrmann, Elizabeth, and Donald D. lV IacLaren, Scotch Plains, NJ., assignors to Esso Research and Engineering Company, a corporation of Delaware Application October 1, 1957, Serial No. 687,498

7 Claims. (Cl. 208-80) conversion with or without C /C alkylation, or steam,

In addition an alkylation process for the cracking.

lighter components from the.l60/260 F. hydroforming and 260/ 330 F. thermal conversion operations may be used. v

The present invention solves a very real problem.

Straight hydroforming produces a gasolinein which the components in thehigher boiling halfof the total boiling range have a much higher octane rating than do the lower boiling components in the front end of the gasoline. This-concentration of ON. in the fback end of the gasoline is known in the industry to give poor octane distribution and poor car performance incertain critical European cars. By the present invention the front end octane deficiency is solved by a process that uses the same fraction of the crude as was previously treated by hydroforming, and from this produces a balanced gasoline of high octane rating; Thus, by the present process it is notv necessary to build up front end octane rating by adding in valuable components obtained; from other fractions of the crude, e.g. from cracking heavier. oils. This is particularly important in those regions where the greater demand for fuel oil over gasoline. makes heavier fractions of the crude more valuable than in those regions where there is a greater demand for gasoline.

Hydroforming may defined as an operation in which a naphtha is contacted at elevated temperatures and pres,- sures, in the presence of hydrogen with a solid catalytic material. As is known, hydroforming is an operation which involves dehydrogenation of naphthenes to form the corresponding aromatics, isomerization of paraffins and carbocyclic compounds, some aromatization of parafiins and hydrocracking of-the higher boiling paraflins. The process results in the production of suflicient hydrogen to supply the requirements of the hydroforming operation.

and'is usually anet producer of hydrogen.

Thermal conversion is a cracking operation carried out in the absence of a catalyst to improve the octane number and volatility of virgin naphtha. such conversion is usually carried out,the virgin naphtha ischarged to a once-through coil only" cracking operatiorr'at 750-1000 p.s.i.g., with the maximum temperature reached in the coil being about 1100? F. The cracked product is quenched and discharged into a tar separator where polymer boiling above 400? F. is removed.

Isomerization is a process in which hydrocarbons boiling substantially in the gasoline range are subjected, in the presence of a catalyst, to heat treatment in the liquid 2,937,133 Patented May 17, 1960 2 or vapor phase to produce a product containing isomeric forms of the hydrocarbons.

Steam cracking is a process conducted preferably at low pressure in the range of 50-100 p.s.i.g..utilizing about wt. percent steam to produce a 30-40 wt. percent conversion to dry gas. A highlyolefinic product is obtained by this process.

Alkylationis a process for the chemical addition of C C or C olefins or mixtures of'these olefins to an isoparaflin, usually isobutane. The alkylation reaction can be promoted byconcentrated sulfuric acid, hydrofluoric acid, aluminum chloride or boron chloride at low temperatures. Thermal alkylation is possible at high temperatures and very high pressures.

The present invention will be more clearly understood by reference to the accompanying drawings. Figure I diagrammatically represents one system for processing the whole naphthafraction from crude. Figure 11 depicts a more complex processing scheme incorporating an alkylation step utilizing the proper components in the lightends from thermal cracking and hydroforming which have been separated by the use of 5 A. molecular sieves.

The use of molecular sievesis a rather new commercial development in the petroleum refining, art. It has, of course, been known for some time that certain zeolites, both naturally occurring and synthetic and sometimes termed molecular sieves,,have the property of separating straight chain from branch chain hydrocarbon isomers as well as from cyclic and aromatic compounds. These zeolites have innumerable pores of uniform size and only molecules small enough to enter the pores can be adsorbed. The pores may vary inv diameter from 3 A. or 4 A. to 15 A.-or more, but it is a property of these zeolites or molecular sieves that any particular product has pores of substantially uniform size.

The scientific and patent literature contains numerous references to the adsorbingaction ofnatural and synthetic zeolites. Among the natural zeolites having this sieving property may be mentioned chabazite. A synthetic zeolite with molecular sieve properties is described in U.S. Pat. 2,442,191. Zeolites may vary somewhat in composition but generally contain the elements silicon,

aluminum and oxygen as well as an alkaliand/or an alkaline earth element e.g. sodium and/or calcium. The naturally'o'ccurring zeolite analcite, for instance, has the empirical formula NaAlSi O .H O. Barrer (U.S. 2,306,- 610) teaches that all or part of the sodium is replaceable by calcium tov yield on dehydration amolecular sieve having the formula (Ca, Na )Al Si O Black (U.S. 2,552,426) describes a synthetic molecular sieve zeolite having a formula 4CaO.Al O .4SiO A large number of other. naturally occurring zeolites having molecular sieve, activity ile.the ability to adsorb straight chain hydrocarbons and exclude or-reject the branch chain isomers and aromatics because of differences in molecular size are described in an article, entitled Molecular Sieve Action of Solids, appearing in Quarterly Review, vol. III, pages 293-320 (1949) published by the Chemical Society (London).

A 5 A. molecular sieve may be prepared by rapidlyturepf about v,F. in proportions such that the mix-v treated'withanflaqueous solution of calcium chloride to replace at least a portion of the'sodium content of said ture has a ratioof SiO Al O of about 1.5 to l. A pre cipitate'fdrnisfinst'antaneously of the desired crystalline sodium aluminum silicate which is then withdrawn'and material with calcium: 3 The material is then calcined to obtain-the desired 5 A. synthetic molecular sieve zeolite. Referring to Figure I, a naphtha boiling up to about 330 F. is supplied through line 1 to distillation column 2. From column 2 a 260/ 330 F. bottoms cut is passed through line 3 to thermal conversion 4. Thermal conver sion is conducted at pressures of 100 to 1000 p.s.i.g. and

C C; normal hydrocarbons adsorbed in zone 22. The raflinate stream containing C and C normal hydrocarbons desorbed from the sieve is passed from the process through line 35. The sieve containing adsorbed olefins at temperatures f 100W 1200? The thermal 5 is passed through line 23 back to adsorption zone 22, cQmfifsion p d aftif Suitable Separation f t and as previously described. From the bottom of column the C and lighter gas is passed through line 5 to jo n 33 the C thermal conversion'product is passed through other process naphthas in line 6. The C /C cut from line 36 to join the other process products in line 27. column 2 is passed through line 10 to fractionator 11 From column 16 the overhead C -C stream is passed where isopentane is separated as theoverhead which is 10 through line 37 to distillation column 38 where high passed through line 12 also to join the other products octaneisopentane is separated as the overhead and the nl The middle Cut boiling from ab011t'160/260a lower octane hydrocarbons are passed from the bottom F; is passed through line 7 to hydroforming g and the of the column through line 39. The isopent ane overhead hydroformate is passed through line 9 also to line 6. is passed through line 40 to join the other process gaso- A balanced, high octane gasoline is so obtained. 15 line components in line 27. If desired, instead of the Referring to Figure II, a diagrammatic representation column 38 fractionation to separate isopentane treatment of an alternate process for carrying out this invention, a of the C -C stream, this fraction may be subjected to virgin naphtha boiling up to about 330 F. is passed isomerization, thermal conversion with or without C3-C through line 15 to distillation column 16 wherein as bealkylation, steam cracking or other processing. fore the cuts are segregated. The middle boiling 160 The following example presented in tabular form is il- 2-60" F. cut is passed through line 17 to hydroforming 18 lustrative ofthe present invention. which is operated under similar conditions to those de- Exam le scribed in connection with Figure I. Hydroformate is p passed through line 19 to debutanizer column 20. Pro- In the following table three processes for carrying out pane, normal butane and isobutane are taken overhead the present invention are compared with the best prior art through line 21 to moving bed molecular sieve adsorption process for treating a wide boiling naphtha. zone 22. Conventional fixed bed molecular sieve opera- In the prior art design steam cracking of the C /C tions may also be utilized in this invention. Molecular fraction is conducted at 1440 F. temperature; 20 p.s.i.g. sieve zone 22 is operated at pressures of 0 to 500 p.s.i.g. pressure; 80 wt. percent steam and and 57.5% conversion and temperatures of 100 to 500 F. In zone 22 the to ,dry gas.- The 160/260 F. cut is processed by fixed normal paraffins in the feed are picked up by the sieve bed platinum hydroforming in the presence of a catalyst displacing at the same time straight chain olefins which Containing Percent Of Platinum deposited 011 are on the sieve material entering from the desorption ated alumina at 900 F. temperature, 300 p.s.i.g. preszone through line 23. The non-normal components pass sure in the presence of 6000 ft. of hydrogen/barrel of overhead along with the displaced olefins through line 24 ed, and a feed rate of 1.8 wts. of feed per hour per to alkylation process 25. Alkylation is conducted at tem- Weight of catalyst. The 260/ 360 F. cut is also processed peratures of about F., pressure of 0 to 10 p.s.i.g., utiby fixed bed platinum hydroforming in the presence of a lizing 98% sulphuric acid for'the fresh catalyst. From catalyst containing 0.6 wt. percent of platinum deposited alkylation the product is passed through line 26 to join upon activated alumina. The conditions are: 900 F. other products of the processes in line 27, and so form 40 temperature; 300 p.s.i.g. pressure in-the presence of 6000 a balanced high octane gasoline. From molecular sieve ft. of hydrogen/barrel feed, and a feed rate of 3.2 wts. adsorption zone22 sieve plus adsorbed propane and nor- Of feed per hour per weight of catalyst. mal butane are passed through transfer device 28 to In the heavy naphtha thermal conversion combination molecular sieve desorption zone 29, operating under process the C /C cut is fractionated at 20 p.s.i.g. presslightly higher than adsorption temperatures of 200 sure, the overhead cut boiling in the range of 80 to 100 to 600 F. and pressures of 0 to 450 p.s.i.g. F. The 160/260" F. cut is platinum reformed under the Referring now back to column 1-6, the 260330 F. same conditions as in the prior art design described bottoms fraction is passed through line 30 to thermal conbo e- Thermal conversion of the 260/ 330 F. cut is version zone 31 which is conducted under similar condiconducted 'at-l100" F. temperature and 200 p.s.i.g. prestions to those described in connection with Figure I. sure. 7 Y j i Thermal conversion product is passed through line 32 In the heavy -naphtha' conversion+C /C al kylation to column 33 where a highly olefinic C -C cut is taken Process alkyl'ation 0f h C3/C4 fraction is Conducted in overhead. Column 33 is a diagrammatic representation the Presence 0150198 Percent Sulphuric acid catalyst of -a two column system. The first column removes the at 40 F. temperature and 7 p.s.i.g. pressure. 0.07 vol. ethane and lighter components overhead and the second 0f Olefin/hfi/VOL acid and 2 4 alkylatiid column takes overhead the highly olefinic C C cut. talyst are consumed. Treatment of the other cuts is as This overhead is passed through line 34 to molecular sieve described above for the heavy naphtha thermal Comte!" desorption zone 29 where it desorbs the sieve of the SiOIl Combination Process.

TABLE Heavy Naphtha Thermal Heavy Naphtha Thermal Heavy N aphtha Base Prior Art Design Conversion CO11V.+Cz/C4 Alkylation Thermal Conv.+ l V Cz/Ca Alkylation (ls/Cr Steam Crkg. RON) ISO/260 F Plat. Ref. (97.5 RON) Plat. Ref. (97.5 RON)-.'

260/330" F Plat. Ref. (80 RON) Thermal COIIV. (81 RON).

Alkyl. Stock.

Front. (80 RON) Fraet. (80 RON) Plat. Ref. RON) Thermal Conv. 31 RON) Fract. (80 RON). Plat. Ref. (100 p r Regular Gasoline:

. ON).- Cs/Ci Alkyl. (94.8 RON) C2/G3AIky1; 95.1 V RON),

Res. O.N.+1.5 cc. TEL 91.6... 92.3 (1.1 cc. TEL) 92.2 92.9. Res. O.N. on Front 75% 79.8-. 86.9... 88. 88.0.

(Equals Road O.N.). Premium Gasoline:

Res. O.N.+1.5 cc. TEL 100.5 100.5.-. 100.0.-. 100.0 (clear). Res 0 N on Front 75% 91.5.- 91.5-. 93.0.... 94.5.

(Equals Road O.N.).

In the heavy naphtha thermal -conversion-=:-+C /C alkylation process C /C cut alkylation is conducted in the presence of aluminum chloridecat-alyst at 120 F. temperature and 400 p.s.i.g. pressure and 2.25# AlClg/ bbl. alkylate: catalyst consumption. Treatment of the other cuts in this process are also as describedabove for the heavy naphtha thermal conversion process;

As can be seen from the-above chart the heavy naphtha thermal reforming combination processtgives a road octane increase of 7 numbers for regular gasoline with an 0.7 research octane number increase over that of the prior art design. The different C /C treatment used in the prior art design does not affect the validity of this comparison of road octanes since all of the product from this light fraction gets into the front end and is 80 octane no matter by which process it is produced There is no improvement in the premium gasoline over .the' prior art design because in this example the premium was obtained entirely from platinum hydroforming of the 160/260 F. out. In these particular examples, equal amounts of premium and regular gasolines are secured by the design of the process. It should also be noted that additional improvement in road octane may be provided by incorporating C /C or C /C alkylation processing of light components available from the process. In this respect looking at the chart it can be seen that C /C alkylation gives a greater increase in road octane for the premium gasoline than does C /C alkylation and less of an increase for the regular gasoline than does C /C alkylation. It would seem that C /C alkylation would be the preferred process based on balancing road octane appreciation obtainable between the two grades but other factors such as the value of the raw materials for other uses and the relative costs of the (T /C as compared to the C /C alkylation processes would have to be considered and might well be controlling.

It is to. be understood that this invention is not limited to the specific example above which has been oifered merely as an illustration and that modifications may bemade without departing from the spirit of this invention.

What is claimed is:

l. The process for producing from a wide boiling naphtha a balanced high octane gasoline having high octane components distributed throughout its boiling range which comprises distilling to separate C /C l60/260 F. and 260/330 F. fractions; suitably upgrading the C /C low boiling fraction, hydroforming the fraction boiling from about l60/260 F., and thermally converting the fraction boiling from about 260/ 330" F.; and combining (I /C upgraded product with the hydroformate and with the thermal conversion product to produce the desired gasoline.

2. The process for producing from a wide boiling naphtha a balanced high octane gasoline having high octane components distributed throughout its boiling range which comprises distilling to separate C /C 160/260" F. and 26'0/330 F. fractions; fractionating the C /C low boiling fraction to separate high octane isopentane, hydroforming the fraction boiling from about l60/260 F., and thermally converting the fraction boiling from about 260/ 330 F.; and combining the isopentane with the hydroformate and with the thermal con- I version product to produce the desired gasoline.

naphtha a balanced high octane gasoline having high octane components distributed throughout its boiling range which-comprises distilling to separate C /C 160/260-' butane raflinate to alkylation; passing thermal conversion product to fractionation to separate overhead a highly olefinic C /C cut, molecular sieving this overhead to separate olefins, and passing said olefins to join previously separated isobutane in an alkylation step, alkylating; and combining isopentane separated from'the C /C cut with hydroformate with thermal conversion product and with alkylate to produce the desired balanced gasoline.

5. The process for producing from a wide boiling naphtha a balanced high octane gasoline having high octane components distributed throughout its boiling range which comprises distilling to separate C /C 160/260 F. and 260/ 330 F. fractions; fractionating the C /C low boiling fraction to separate high octane isopentane, hydroforming the fraction boiling from about 160/260 F. and thermally converting the fraction boiling from about 260/ 330 F.; fractionating the hydroformate to separate overhead propane, normal butane and isobutane, molecular sieving this overhead to remove propane and normal butane on the sieve, passing mainly isobutane raflinate to alkylation; passing thermal conversion product to frac- 3. The process for producing from a wide boiling naphtha, a balanced high octane gasoline having high octane components distributed throughout its boiling range which comprises distilling to separate C /C 160/260" F.," and 260/330 F. fractions, steam cracking the C /C low boiling fraction, hydroforming the. fraction boiling from about 160/260 F. and'thermally converting the fraction boiling from about 260/330 F.; and combining C /C cracked product with the hydroformate and with the thermal conversion product to produce the desired gasoline.

4. The process for producing from a wide boiling desired balanced gasoline.

tionation to separate overhead a highly olefinic C3/c3 cut, molecular sieving this overhead to separate olefins, and

passing said olefins to join previously separated isobutanev in an alkylation step, alkylating; and combining isopentane separated from the 0 /0 cut with hydroformate, with the thermal conversion product and mm the alkylate to produce the desired balanced gasoline.

6. The process for producing from a wide boiling naphtha a balanced high octane gasoline having high octane components distributed throughout its boiling range which comprises distilling to separate C /C /260 F. and 260/330 F. fractions; fractionating the C /C low boiling fraction to separate high octane isopentane, hydroforming the fraction boiling from about 160/260 F. and thermally converting the fraction boiling from about 260/330 F.; fractionating the hydroformate to separate overhead propane, normal butane and isobutane, passing this overhead over molecular sieves containing adsorbed C /C olefins, passing the combined desorbed olefins from said sieve and isobutane rafiinate to alkylation; passing thermal conversion product to fractionation, separating overhead a highly olefinic (I /C cut, passing this overhead over sieves containing propane and normal butane from the above described sieve treating zone, separating olefins adsorbed on the sieve, passing sieve containing adsorbed olefins ,to the first described molecular sieve treating zone, alkylating; and combining isopentane separated from the C /C cut with hydroformate with thermal conversion product and with alkylate to produce the 7. The process for producing from a wide boiling naphtha a balanced high octane gasoline having high octane components distributed throughout its boiling range which comprises distilling to separate C /C 160/260"; F.

and 260/ 330 F. fractions; fractionating the C /C low assume 7 thermal conversion product to fractionation, separating 7 References Cited in the file of this patent overhead a highly olefinic (D /C cut, passing this overa 1 head over sieves containing propane and normal butane UNITED- STATES PATENTS from the above described sieve treating zone, separating 2,249,461 Diwoky July 15, 1941 olefins adsorbed on the sieve, passing sieve containing ad- 5 2,304,1 8? I Marsehner Dec. 7 8, 1942 sorbed' olefins to the first described molecular sieve treat- 2,401,649 I Lefr'er; June 4, 1946 ing zone, alkylating and combining isopentane separated 2,678,263 Glazier May 11', 1954 from the C /C cut with hydroformate with thermal con- 2,740,751 Haensel et al. Apr. 3, 1956 version product and with alkylate to produce the desired 2,818,449 Christensen et a1 -4 Dec. 31, 1957 balanced gasoline. t 10 2,859,173 Hess et al. Nov. 4, 1958

Claims (1)

1. THE PROCESS FOR PRODUCING FROM A WIDE BOILING NAPHTHA A BALANCED HIGH OCTANE GASOLINE HAVING HIGH OCTANE COMPONENTS DISTRIBUTED THROUGHTOUT ITS BOILING RANGE WHICH COMPRISESDISTILLING TO SEPARATE C5/C6 160/260*F. AND 260/330*F. FRACTIONS, SUITABLY UPGRADING THE C5/C6 LOW BOILING FRACTION, HYDROFORMING THE FRACTION BOILING FROM ABOUT 160/260*F., AND THERMALLY CONVERTING THE FRACTION BOILING FROM ABOUT 260/330*F., AND COMBINING C5/C6 UPGRADED PRODUCT WITH THE HYDROFORMATE

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