US2371355A - Motor fuel - Google Patents

Description

March 13, 1945.-

w. B. Ross ETYAL MOTOR FUELS Filed Nov. 1, 1941 INV ENT ORS Patented Mar. 13, 1945 UNITED STATES PATENT ori-ica MOTOR FUEL william n. Ross, Evanston, and Kenneth' Boldt, y Highland Park, Ill., assignorato The Pure Oil C'ompanyzChicago, lll., a corporation of Ohio Application November 1,1941, serial No. 417,438 y g s claims. (ci. 19e-5o) This invention relates to the manufacturek efrf high anti-knock gasoline having a well-balanced distillation vrange and -unusually eilective road performance in modern internal combustion en,- gines, and more particularly to an integration of steps which involve separately treatlngby ther-l mal and catalytic steps fractions 'obtained by fractionation of relatively'vwide boiling range hydrocarbon mixtures such as crude oil, particularly crude oil in which the gasoline boiling con- In a speciiic embodiment, the present inven- .K tion comprises fractionating a mixtureof hydrocarbons oi widely divergent boiling rangev such as, for example, crude oil, particularlystituents are of the saturated type. whereby to obtain a well-balanced boiling range gasoline of high anti-knock properties having s. high proportion of unsaturated hydrocarbons in the low boiling fraction and not more than a minor amount of unsaturated hydrocarbons in the high boiling portion. Y

Experience has shown that highly oleinic motor fuels have certain inherent4 disadvantages. First, their susceptibility 'to lead, is low as compared with vparailinic hydrocarbons. Furthermore, under high speed operating conditions oleiinic motor fuels have a tendency to cause knocking in modern automotive enginesof high compression ratio.

It has been foundh that 4these disadvantages may be overcome and particularly effective allspeed performance and high lead susceptibility may be obtained by controlling the chemical composition-boiling range relationship in. the gasoline. The preferred gasolines are those in which the low boiling portion oi the gasoline-that is, the portion boiling from approximately 100 to 140 F.is predominantly unsaturated in character and in which the high boiling portionthat is, the portion boiling from approximately 235 to 400 F.contains not more than a minor amount of aliphatic unsaturated hydrocarbons. The intermediate portion of the fuel-that is, the portion boiling from approximately 140 to 235 F.-may consist of any type oi' hydrocarbons so long as the octane number oi' this fraction is suilciently high to maintain a high overall octane number in the nnished motor fuel. The boiling points of the aiorementionedfractions are determined using an apparatus having a packed fractionating column and in which a relatively high reflux ratio is employed. 'Fuels which have the aforementioned chemical composition-boiling range relationship produce unusually eifective road performance -in modern internal combustion engines. As used throughout this, specification and inthe claims, the terml "unsaturated hydrocarbons" does not include aromatic hydrocarbons.

highly paraiiinic crude oil ci' the type obtained from Michigan and Pennsylvania producing areas, lto produce gas, light gasoline distillate,

heavy gasoline distillate and residual cracking stock; supplying said gasin admixture with gases from other steps of the process to be vsubstquently described, to a fractionation zone and therein separating vnon-condensable gases consisting largely of hydrogen, methane and ethane. from normally gaseous hydrocarbons .of higher molecular weight such as Ca and C4 hydrocarbons;'supplying said last-mentioned hydrocarbons tota catalytic or thermal polymerization or alkylation zone toconvert a substantial portion of the hydrocarbons charged into high octane hydrocarbons of motor fuel boiling range; separating the conversion products of the polymerization or alkylation zone into gas, gasoline dill-` tillate and heavy oil boiling above the gasoline boiling rangeand blending the gasoline distillate with other gasoline fractions to produce a com' posite motor fuel; charging llight gasoline" distillate separated in the initial fractionation stepv to a catalytic dehydrogenation zone whereby to produce substantial proportions of high octane' unsaturated hydrocarbons of gasoline boiling range and a gas fraction; supplying the gas iraction to the rst-mentioned gas fractlonating step and blending the gasoline vfraction with other gasoline fractions to produce a composite mo- Amotor fuel; charging the residual cracking stock separated in the initial fractionationstep to a catalytic cracking or thermal vapor-phase cracking step whereby to produce substantial propertions of gasolineboiling range hydrocarbons of high octane value; separating the conversion products from the aforementioned cracking zone into gas, gasoline distillate, recycle stock and Another object of this invention is to produce motor fuels of high anti-knock rating and smooth curve boiling range having apredominant proportion of unsaturated hydrocarbons in the fraction boiling up to approximately 140 F. and not more than a minor proportion of un-` saturated aliphatic hydrocarbons and a major' proportion of isoparailins and/or alkylated benzenes in the fraction boiling above approximately 235 F.

A further obiectof this invention is to provide a method for eillciently converting high proportions of wide boiling range hydrocarbon mixtures by thermal and catalytic steps wherein each speciiic step is correlated with other steps to provide maximum thermal and operating eiliciency to produce motor fuel possessing unsually high road performance characteristics.

. A further obiect of the invention is to produce motor fuel of high anti-knock rating having a predominant proportion of unsaturated .hydrocarbons in the low' boiling range and not more hydrocarbons in the high boiling range.

A still further object f the invention yis to, provide a method for producing improved motor fuels by proper treatment ofparticular fractions and re-blending of the fractions after treatment. l

Other objects of the invention will become apparent from the following description considered in conjunction with the accompanying drawing, the single gure of which is a diagrammatic now sheet illustrating a specific form of the invention. A flow sheet has been used in order to illustrate the invention without complicating the drawing' with unnecessary processing details of each specic step, since those skilled litre the art are familiar with the\details of these s ps.

Referring to the accompanying drawing, hydrocarbon oil of wide boiling range, particularly contacted with phosphoric acid catalyst at temticularly described in Holm et al. Patent No. 2,186,021-, When a thermal, or non-catalytic, polymerization step is employed, the gases are subjected .to temperatures of the order oi 850l100 F. at pressures of about 400 to `2000 pounds per square inch for s. sufiicient time to produce substantial quantities of gasoline boiling range hydrocarbons. Further specific details oi conditions suitable for thermal polymerization are set forth in Wagner Patent lio. 2,157,225. In the event that it is desired to subject the heavy gases 25 to an alkylation step, the gases are contacted with a sulfuric acid catalyst at low superatmoshpheric pressures and temperatures oi' about 15-l50 F., as is more particularly described in the patent to Holm et al. No. 2,244,556. Irrespective of the particular process to which the heavy hydrocarbonvgases are subjected, the conversion products from the catalytic or thermal polymerization or alkylation zone 2l are separated into gas Z9, gasoline distillate 3l and heavy oil 33. The gasoline distillate thus obtained is blended with other gasoline fractions obtained in the process to produce a composite motor fuel.

The light gasoline distillate obtained from the initial crude oil fractionation step usually has a boiling range of about 100 to 235 F., and when Michigan or Pennsylvania type crude oils are employed, is highly paramnic in character and of relatively low octane number. 'I'his distillate is $5 supplied to catalytic dehydrogenation zone 35 than a minor proportion of unsaturated aliphatic i and therein subjected to temperatures of the order of 752 to 1292 F. in contact with suitable catalysts suchy Yas aluminum or magnesium oxides supporting oxides of elements in the lett-- hand columns of the fourth, iifth and sixth groups of the periodic table to lproduce unsaturatedhigh octane hydrocarbons of substantially the same boiling range as the fraction charged.

Michigan or Pennsylvania type crude oil, is supplied to a fractionation zone I l .and therein separated into -gas Il, light gasoline distillate is, heavy gasoline distillate i1 and residual cracking stock I9. The gas fraction i3 in admixture with gases obtained from other steps of the process as will, be subsequently described, is supplied toJa gas fractionation zone v2l and therein fractionated into light gases 23 consisting largely of hydrogen, methane and ethane and heavy gases 25 such `as C: and U4 hydrocarbons. The heavy gases are supplied to a catalytic or thermal polymerization'or alkylationzone 21 in' order to conyert a substantial proportion ofthe hydrocarbons charged to this zone into high octanehydrocarbons of motorA fuel boiling range'. Itis preferred to employ catalytic or thermal polymerization'.

in subjecting the heavier gaseous hydrocarbons initial crude oil fractionation step preferably has Suitable dehydrogenating conditions are more particularly described in Grosse Patent No. 2,231,446. Conversion products from the catalytic dehydi'ogenati'on step 35 are separated into gas 81 and gasoline distillate 39. Gas 31 is admixed with gas obtained from the initial crude oil fractionation step and supplied to gas fractionation zone 2i. Gasoline distillate 33 which is of high octane number and of relativelyhigh unsaturate content is blended with other gasoline fractions produced in the processto form 'thecomposlte gasoline. l

Heavy gasoline distillate i1 obtained from the a boiling range of approximately 235 to 425 F.

,This distillate when employing crude oils of the aforementioned type is also highly paramnic in character and of very low octane number. VThe distillate is supplied 'to a catalytic hydr'oforming or isomerizing step 4i wherein the hydrocar- -bons charged are converted into substantial proportionsof high octane hydrocarbons .aoiling'in the upper portion of gasoline boiling range and containing-notmgre than minor amounts, usuall ly very small amounts, of unsaturated hydrocarbons. When employing a catalytic hydroforming step the heavy gasoline distillateis subjected to temperatures of about 950 to 1050 F. and pressure of about 300`to 3900 pounds per square inch incontact with suitable catalysts such as the 25 to catalytic polymerization, the 5888 may bel 7| oxides of metals of the third,'nfth or sixth groups ofthe periodic table alone or on a sup? lport such -as activated alumina, silica or pumice.

vFurther specific details of suitable operating whereby to .produce high yields of substantially saturated gasoline boiling range high 'octane hydrocarbons.- Further specic details of such a process are foundy in Lynch et al. Patent No.

2,223,180. Conversion products from the c atalytic hydroforming or isomerizlng step 4I are separated into gas 43 and gasoline I5'. The gas is admixed with gas obtained fromthe initial -crude oil lfractionation step and supplied to gas fractionation zone 2l. Gasoline. is blended with other-gasoline distillates produced -in `the process to'form the composite gasoline.

Residual cracking stock I9, -preferably at elevated temperature as a result of the initialfractionating step, is. supplied to cracking zone l1 and therein subjectedv tocatalytic cracking or thermal vapor phase cracking in order to progce high yields of high octane number gasoline lling range hydrocarbons. When catalytic cracking of the cracking stock I9 is employed, anyone of several lprocessesmay be used, the .preferable ones being those that produce the highest proportions of unsaturated hydrocarbons ing portion. Suitable cracking processes includethe I-Ioudry"A and 0. R.. A." processes. The Houdry process is described in numerous patents I, in the low boiling portion and minimum amounts i of unsaturated hydrocarbons in the high boilsuperatmospheric pressure for a sumcient time to produce substantial proportions. ofzfhighpoctane gasoline boilingf range hydrocarbons'..i.1f Suitafble conversion conditions are more fully set` forth in Greenstreet Patent No. 1,386,093. *i

Irrespective of the particular cracking'process v employed, the conversion products are separated into gas 49, gasoline distillate 5I, recycle stock .53 and residuuml 55. The gas fraction-49 is acln mixed with gases separated from the initial crude oil fractionating step and supplied to gas fractionation zone 2l. Gasoline distillate 5I is blended with, other gasoline distillates produced in the process`to form the composite gasoline.

In the event that gasoline distillate 5| oonteins high proportions of unsaturated hydrocarbons boiling in the upper portion-Lof the gasoline range, it is desirable to convert a substantial proportion of these .compounds into saturated compounds of high octane number and of gaso line boiling range. late 5l is subjected to fractionation in fractionating zone 51 and therein separated into aA low boil- -ing gasoline fraction 59 having an end point of approximatel'y 235 F.- and a high boiling gasoline fraction '6I having a boiling range of approximately 235 to 425F.- The low boiling gasoline fraction'- 59, being of a highly unsaturated character, is blended direct with other gasoline fractions 'to' form the composite gasoline. The high boiling unsaturated gasoline fraction 6I is'subjected to catalytic hydroformlng or isomerizing in conversion zone 4 I. 'I'he hydroforniing or isomerizing step may be carried out separately from or preferably in admixture with .heavy gasoline distillate I 1 obtained fromthe initial crude oil fractionating, step. A

It will be seen from a consideration of the foregoing description that a process has'been described 4o wherein a#l high proportion o f the hydrocarbons as, for example, Patent No. 2,161,676. The C.

R.. A. process is particularly suitable for producing gasoline hydrocarbons in accordance with this invention and is very suitable for operation in conjunction with the other processes described herein; In this process the cracking stock is subjected to temperatures of ,the order of 8302 F. in 'order to vaporize' a substantial portion of the hydrocarbons, the vaporized hydrocarbons sep,- arated from u nvaporized liquid, admixed with steam and catalyst and maintained in a reaction zone under conditions of temperature of the order of 950 F. and low superatmospheric pressur'es of about 10 pounds per square inch for a. time suitable to leect the desired conversion into high octane hydrocarbons. catalyst such as silica, alumina or activated clays Y Very finely dividedv l is employed Aand is maintained in suspension in v/,hydrocarbon reaction products pass through a 'fractionation step and are separated into the dein the high boiling range,

found in crude oil is eiliciently utilized for producing gasoline `containing predominant proportions of unsaturates in the low boiling range and not more than minor proportions of unsaturates which gasolines have been found capable 'of producing unusually eifective road performance in modern internal combastion engines.

The specific operating conditions which may be` employed in successfully conducting the-various steps of the process will vary considerably de-` pending upon the type of crude oil charging stock employed, the particular composition of the fractions subiected to conversion in each ofthe individual cooperative steps and the specific type *of catalyst employed in the catalytic conversion zones. Since the regulationof the operating conditions in each of the individual step to accomplish the object herein set -forth is within the skill of those working in ,the art, no attempt has been made toherein'deiine the Although reference has been made to specific patents in connection with various steps in the 1 process, 1t should be understood that the patents A, have been cited as being merely illustrative of Y the particular steps. For example, other methfractions. When thermal vapor phase norm of tneereeking stoor lo is employed,

the cr'a'ckingstock is subjected to elevated temperatures tovaporize a substantial portion of the hydrocarbons andthe vaporize'd hydrocar- I bons maintained in.a.conversion sone at temperatures of about-1100' to 115003,11'.y under low ods are known for the isomerization lof paraiilns to iso-parailinl hydrocarbons. -The same is true of the hydro-forming and catalytic cracking steps. The various steps` in the process are limited, therefore. only by the following denitions:

Catalytic dehud rogeftat'lon.f-A` for l.

converting saturated `gasoline boiling range hylnto unsaturated gasoline boiling In this case gasoline distil-` specic limits of I .satisfactory ,operating conditions.

-range hydrocarbons of high anti-knock value in the presence'of a catalyst. y

Hydroforming.-A process for catalytically converting non-aromatic hydrocarbons boiling approximately within the gasolineA range into alkylated cyclic hydrocarbons boiling approximately within the gasoline boiling range.

Isomerizatz'on.-A process o! catalytically converting straight chain hydrocarbons boiling approximately within the gasoline boiling range into vbranched chain hydrocarbons of approximately the same boiling range,

,Catalytic cracking- A process for thermally converting higher boiling hydrocarbons into gaso` li'ne boiling hydrocarbons in the presence of a catalyst.

Thermal vapor phase crackingf-A process for converting higher boiling hydrocarbons in the vapor state into gasoline boiling hydrocarbons by purely thermal means, i. e., without the use of a catalyst.

Catalytic polymerization-A process for converting normally gaseous hydrocarbons into gasoline boiling range hydrocarbons in the presence of a catalyst.

Thermal!l polymerization-A process for con- -verting normally gaseous hydrocarbons into hydrocarbons of gasoline boiling range by purely thermal means, i. e., without the use of a catalyst. 'AUcyZattOnf-A process for catalytically converting mixtures of normally gaseous saturated and unsaturated hydrocarbons intosubstantially saturated high octane gasoline boiling range hydrocarbons.

While the invention has been shown and detemperatures oi approximately 752 to 1292q l'.`

to produce unsaturated hydrocarbons of gasoline l boiling range; separating gas and gasoline dis- A tillate 'from the dehydrogenati'on conversion products, subjecting said heavy gasoline distillate to hydroforming in the presence of a hydro-` forming catalyst and hydrogen at elevated pressures and at temperatures or approximately 950 to 1050 F., separating gas and gasoline distillate -i'rom the hydroformin'g conversion products, subjecting said residual cracking stock to thermal vapor phase cracking, separating gas, low boiling gasoline distillate and high boiling "gasoline distillate from the cracking conversion products, supplying said high boiling gasoline distillate to Asaid hydroforming step, subjectingiheavy constit uents of the gas from the initial crude oil fractionating step, .gas from the dehydrbgenation step, gas from the hydroforming step and 'gas from the cracking step to` polymerization to produce substantial amounts or high octane gasoline boiling range hydrocarbons, separating gas and gasoline from the polymerization conversion products and combining gasoline distillate from the `dehydrogenation step, gasoline distillate from the hydroiorming step, low -boiling gasoline annum mm the cracking step and gasoline from the polymerization step to produce the dcaired high octane composite gasoline;

2. In a process for converting crude oil into gasoline, the steps of separating from the crude oil a light gasoline and a heavy gasoline iraction subjecting the light traction to dehydrogenation in the presence of a dehydrogen'ating catalyst at temperatures of approximately '752 to- 1292- F. in order to convert the parailinic hydrocarbons izo/unsaturated hydrocarbons, subjecting the heavy' gasoline fraction to hydroforming in the presence of a hydroforming catalyst and hydrogen at elevated pressures and attemperatures of approximately 950 to 1050 F. whereby paraiiinic hydrocarbons are converted into high octane number alkylated ring hydrocarbons, and blending the gasoline fractions recovered from the two steps to make a high anti-knock quality gasoline.

3. In a process for converting crude oil into gasoline, the steps of separating from the crude oil a light gasoline fraction boiling within the range of about to235 F. and a heavy fraction boiling within the range of approximately 235 to 425 F., dehydrogenating the light fraction in the presence of a dehydrogenating catalyst at temperatures of approximately 752 to 1292 F. to convert parailinic hydrocarbons into oleiinic hydrocarbons, hydroiorming the heavy fraction in the presence of a hydroforming cat alyst andhydrogen at elevated pressures and at temperatures of approximately 950 to 1050 F. into aromatic lwdrocarbons of high anti-knock and blending the fractions after conversion to produce a gasoline of high anti-knock quality.

4. In a process in accordance with claim 2, the steps of subjecting crude oil fractions boiling above` the gasoline range to high temperature cracking, separating a light and a heavy gasoline fraction from the reaction products, converting the heavy fraction together with the heavy gasoline traction separated from the crude oil and blending the resulting converted lgasoline from the hydroforming operation with the light straight run and cracked gasoline fractions tof make the finished gasoline. l 15,'In a process for converting crude oil into anti-knock gasoline, the steps of separating from the crude oil a light gasoline fraction boiling in the range of about 100 to 235 F., a heavy gaso line fraction boiling within the range of approximately 235 to 425 F. and a fraction heavier than gasoline, subjecting the latter fraction to high temperature cracking in order to produce a fraction boiling up to about 235 F. of highly unsaturated character and a fraction withinl the approximate boiling range of 235 to 425 F., combining the two fractions boiling within the range of 235 to 425 F. and subjecting them to hydroiorming in the presence of a hydroforming catalyst and hydrogen at elevated pressures and at temperatures of approximately 950 to 1050 F., subjecting the initial light'fraction to dehydrogenation in the presence of a dehydrogenating catalyst at temperatures of approximately '152190 l292 F. and combining the converted hydrocarbons from the foregoing steps to produce the desired anti-knock gasoline.

wnmM B. Ross. KENNEIH BoLD'r.

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