US2255399A - Process for cracking and polymerizing hydrocarbons - Google Patents

Description

' Sept. 9, 1941. P. sUBKow ETAL 2,255,399

PROCESS FOR CRACKING AND POLYMERIZNG' HYDROCRBONS 2 sheets-sheetv 1 Filed Oct. 29, 1955 A sept. 9, 1941.

IP. suBKow ETAL PROCESS P OR CRACKING AND POLYMEI'QIZING` HYDROCARBONS Filed Oct. 29, 1935 2 Sheets-Smelt 2 Patented Sept. 9, 1941 I PROCESS FOR CRACKING AND POLYMERZ- ING HYDROCARBONS Philip Subkow, Los Angeles, Earle W. Gard, Palos Verdes Estates, and Robert E. Haylett, Long Beach, Calif., assignors to Union Oil CompanyJ of California, Los Angeles, Calif., a corporation of California Application October 29, 1935, Serial No. 47,238

(Cl. 19o-10) 3 Claims.

This invention relates to process for the formation of high anti-knock gasoline and particularly to processes for the conversion of low antiknock gasoline and kindred fractions and the conversion of normally gaseous petroleum fractions into high anti-knock gasoline. The low anti-knock gasoline fractions are treated by modification of the process known as reforming which utilizes recombining and Apolymerizing reactions as well as decomposing reactions. The treatment of the normally gaseous hydrocarbons (and in some instances the low antiknock gasoline) involves the building up of higher molecular weight hydrocarbons of high anti-knock quality'by dehydrogenation accompanied by polymerization or synthesis and by molecular re-arrangement known as isomerization. The process also involves the conversion of high molecular weight' liquid petroleum fractions into lower molecular weight hydrocarbons by the processes known as cracking dehydrogenating" and reforming. 'I'he invention involves further the production of highantiknock gasolinas from liquid fractions as above mentioned while in contact with the normally gaseous fractions above mentioned by a combimolecular weight hydrocarbons.

nation of the processes for the conversion of the mentioned liquids and gases.

The conventional process for the reforming of gasoline consists in subjecting gasoline, kerosene or gasoil, preferably in vaporous form, to high temperatures under conditions whereby the stock is converted from one having low antiknock properties to one in the gasoline range having high anti-knock properties. The gasoline is then separated from the fixed gases and normally gaseous hydrocarbons to yield a stabilized reformed gasoline. This process for the formation of high iso-octane number material may be visualized as proceeding through cracking, dehydrogenating and isomerizing reactions which yield as an intermediate or by-product, low molecular' weight oleilnic fractions and chemical radicals with unsatisfied valences, these materials being called residuals In conventional reforming operations no attempt is made to control the subsequent polymerization of these materials to retain and conserve those desirable anti-knock characteristics and to polymerize the gaseous residuals to liquid hydrocarbons of high anti-knock value.

The principal object of the invention, therefore, is to conserve gases made in reforming operations and to convert them, as by polymerizing and synthesizing, into high anti-knock gasoline-like materials, as well as'to convert other gases andl liquids to yield similar anti-knock .fractions in the gasoline range, whereby polymer The reactions here generically termed polymerization include alkylation reactions wherein saturated .hydrocarbons react with unsaturated hydrocarbons to form higher molecular weight branched chainhydrocarbons, and alkylation reactions between aromatics and unsaturated low molecular weight-hydrocarbons such as ethylene, propene or butene, and straight polymerization reactions wherein olens such as monoor diolefins are polymerized to higher molecular weight polymers. Isomerization, although not strictly a polymerization reaction in the sense Vthat higher molecular Weight bodies are formed,

is included within this term since it occurs along with such polymerization reactions. The -term polymerization as here used is intended to embrace these types of reactions for building higher molecular weight bodies by reaction of lower The gasoline produced by this process is termed "polymer" gasoline, and when produced as a mixture with reformed gasoline it is here termed "reformed and polymer gasoline. The term reforming is intended to embrace the 'reactions of cracking or decomposition, dehydrogenation and isomerization by which low octane material of gasoline or higher boiling range is converted into gasoline fractions of high anti-knock properties.

This invention seeks to reform gasoline under such conditions that along with the cracking, de-

hydrogenating and isomerizing operations there,

will be' a parallel, subsequent or conjoint polymerizing reaction Where the gases formed in or added to a reforming operation are converted into polymerized materials, whereby a blend of reformed and polymer gasoline of high, antiknock characteristics is formed directly in the process. It is also sought to so treat similar petroleum fractions, also to utilize various gases both saturated an unsaturated, but preferably the latter, obtainable either from the'process itself or from other petroleum rening operations: and also to synthesize or polymerize such gases as above mentioned in order to produce jtherefrom gasoline of high anti-knock qualities.

The invention may -be said to reside in one aspect in the reforming of liquid hydrocarbons, particularly hydrocarbons inthe gasoline range (although higher boiling range materials also may be employed), for the purpose of producing hydrocarbons having boiling points in the Easoline range but of high anti-knock value and also for the purpose of producing vapors or gases containing Ahydrocarbons offour or fewer carbon atoms;- the vapors being then separately polymerized if desired, or being polymerized in the presence of gasoline ,fractions produced inthe reforming operations, orbeing partially polymer and reformed gasoline are obtained.

ymerizedy separately and then further polymerized 'in the presence of the gasoline fractions being produced in the reforming operation. The invention resides further in treating gases or vapors, either saturated or unsaturated, by heating the same under conditions of temperature and pressure so as to effect polymerization, or a modication thereof as by cracking followed by polymerization, accompanied possibly by isomerization of some of the polymerized or modified materials whereby liquid fractions of high antiknock value are produced. The invention resides also in the addition of hydrocarbons having four or fewer carbon atoms to gasoline to increase the concentration of these low molecular weight hydrocarbons in the gasoline prior to the reforming of the latter.

The process of this invention provides for a controlled polymerization and isomerization of those gaseous residuals and olei'lns heretofore mentioned, particularly those of the ethylene type, so as to favor continued decomposition of petroleum hydrocarbons and an increased yield of high anti-knock material over that produced from a simple reforming operation. The invention also includes the treatment of liquid fractions by cracking, dehydrogenating and reforming operations to produce materials of high antiknock value including rearrangement of gasoline-like materials with low anti-knock characterlstics and the cracking of higher molecular weight materials to -produce lower molecular Weight materials with or without parallel operations involving reforming or polymerization including dehydrogenation, whereby high antiknock liquids are produced. The invention also includes the reforming and polymerization of the normally liquid materials described in the presence of hot cracked' products resulting from the cracking of normally gaseous hydrocarbons or kindred light hydrocarbons obtained from a lowpressure cracking operation, or from a high pressure cracking operation following low pressure cracking, or from both such operations. The invention also includes the recycling of liquid materials obtained particularly from vapor phase cracking of the liquid stocks to the vapor phase cracking system as well as the recycling in the gas cracking system of liquid materials obtained therein. The

control of the treating conditions both in the vapor phase cracking system and inthe gas f cracking system unit, and the conservation of the residual gaseous materials, involve the recycling of the normally gaseous products from both the gas cracking and vapor phase cracking system,

these normally gaseous materials being recycled to the gas cracking system, and preferably by way of an absorption system in which they may be separated from any normally liquid materials associatedwith them.

As a preferred form, the invention resides in vaporization of normally liquid hydrocarbons preferably under pressure, commingling with said vapors crackedy gases resulting from either a low or high pressure cracking operation, or both, followed by subjection of the mixed-gases and vapors to treatment in a cracking furnace under pressurewhereby polymerization, isomerization and .reforming take place. In all instances, the heat treatment is effected under desirable conditions .of temperature and pressure to attain the ends desired, and the materials derived .from these heat treatments are fractionated in suitable ap- 'i paratus for the separationand recovery of the' `materials desired as products and the materials desired for recycling.

1000 F., that is, in

'Ihe reactions which have been termed polymerization reaction, and reforming reaction are parallel reactions. These reactions are generally reversible,.the reaction in one direction being a polymerization reaction, and the reaction in the other direction being areforming reaction.

Consequently, inthe polymerization operation and in the reforming operation, all reactions may occur.` In general, the polymerization reactions are favored by higher pressures and low'er temperatures, while' the reforming reactions are to prevent the reforming reaction from going too far, thus forming light, undesirable. fractions, or from allowing the polymerization reaction to form undesirable heavy bodies by too long a polymerization time. Y j l Normally gaseous hydrocarbon such as propane, butane, propylene or butylene may be polymerized. Instead of using the hydrocarbons having four or fewer carbon atoms, stabilized or wild natural gasoline containing ,these fractions may be employed or stabilized or wild similar fractions from various refinery operations. It is in general preferred, however, to' use hydrocarbons ofv the unsaturated type. Sources of suchgases are processes in which gasoil and/or, fuel oil and the like are cracked atrtemperatures belowabout t Ie neighborhood of 850 tov 950 F. il

The operations perf rmed upon the normally gaseous hydrocarbons, and the reforming operation employed upony gasoline-like fractions which operation is at least partially a combined cracking, dehydrogenating and isomerizi-ng operation, may be aided by choice of conditions of temperature and pressure and rate of feed, and

if desired byv selection of catalysts. In general,l

high temperatures, short time and moderate pressures are desirable. Temperatures may range from 650 to 185.0" F. but the range from about 850 to 1200 F. is preferred. Pressures ranging from atmospheric to as high as 3000 lbs.-

may be employed, but lower pressures, for instance in the neighborhood of up to 1000 lbs. are to be preferred. Reforming or polymerizing catalysts which may be used for the processes herein described will be discussed more fully hereinafter.

, vIn carrying out the process of this invention, the following principles may serve as guides. The feed of liquid fractionspreferably has an end point'not inrexcess of 650 F. Usually a heavy gasoline fraction or'the'like boiling between about 300 to 500 F. will prove satisfactory. However, light gasolines, including lstraight run gasoline and natural gasoline, both stable and wild, and

gasoline-like fractions, both stable and wild, ob-

tained from the recycling gases produced in the cracking operations ofthe present operations or -other cracking operations may be employed. .Heavier similar fractions also may be treated.

The yield ,of polymerization products from the treatment of these liquid materials may be in 4'1li creased by adding to the reaction mixture hydrocarbon materials of :tive or fewer carbon atoms obtained either from the system itself `or from extraneous sources. These may be cracking still gases or gas from any gasoline stabilizing tower the concentrations of the reactants. This may be accomplished by increasing the pressure, and also by adding materials undergoing polymerization,

. as by addition ofthe above mentioned gases to reformed vapors. Such gases are those employed -in the gas-cracking and polymerizing operations also here presented. It is desirable to have present unsaturated hy drocarbons such as butenes, propenes and ethylene. cracking of gas oil or fuel oil at temperatures from 850 to 1000"' F. and preferably,from 900 to 950 F. The gases are those obtained after the cracked gasoline has been removed. Other processes `for -producing these unsaturates may be employed t'o produce the unsaturated normally gaseous hydrocarbons here added to the poly- 'Ihe gases may be obtained from the merization and reforming operations, as hereiny described. The saturated normally gaseous hydrocarbons undergo dehydrogenation and polymerization during the reforming operation. The decomposing reactions occur best at low pressures and the polymerization at higher pressures, although there is an overlapping of these reactions in both instances. It, therefore, may be desirable to increase the pressure in passing i vthrough the gas polymerization stage. The practical dimculty of compressing hot vapors makes this step dfcult, but this may be facilitated by first cooling the vapors, or using a liquid packed surge pump or diaphragm pump or 4the like, or reducing the pressure differential in some instances. The use of catalysts could be adopted to permit the use of lower pressures for the polymerizing reaction and 'lower temperatures for the reforming reaction than would be possible Without the catalyst. y

While the processes of reforming and polymerization are two distinct processes which may be separated the one from the other by careful choice of conditions or catalysts for controlof conditions, as previously described, the two processes may be interwoven.

lThe cracking and dehydrogenating processes of reforming are reversible reactions, and concomitant with them occur polymerizing and hydrogenating reactions.

. ence of the hydrocarbons within thel gasoline range formed as a result of the reforming operation. By` such a combined process, the Flow molecular weight olefinic products of the. forming processes are continuously and progressively a. removed by polymerization from the reaction zone as they are formed, thus favoring continued reforming of the petroleum hydrocarbons and an increased yield of high octane material over that resulting from a simple reforming operation. ,The

A The unsaturated bodies formed as a result of the cracking and dehydro- .genation are extremely active and tend to comforming results in products including a polymer and reformed gasoline fraction of. high octane and having an end point of from 300 to 400 F. depending on operations, a heavy gasoline-kerosene frction having an end point of about 500 to 550 F. and the like. The heavier fractions such as the. heavy gasoline-kerosene 'may be recycled; it will lbe understood that only a portion may be returned and the remaining portion sent tol storage or re-run on blending stock with the polymer and reformed gasoline.

In the accompanying drawings, wherein various systems for practicing the present invention ar disclosed by 'way of illustration- Fig. l is a schematic flow sheet disclosing various units for-'gas treatment and polymerization by Way of gas cracking and for vapor phase cracking, reforming andv polymerization both with and without the aid of previously cracked gases; Fig'. 2 is a schematicflow sheet'.for the polymerization of gasesinvolving gas cracking, polymerization and isomerization including recycling of liquid lfractions produced thereby and gaseous fractions; and Y f Fig. 3 is a similar view disclosing the reforming and polymerization of liquid lfractions in Whichmay be involved the use of gaseous materials obtained following low or high pressure gas-cracking or both.

With reference to Fig. 1, major units are indicated by letters. (Corresponfing units are employed and similarly indicated in Figs. 2 and 3.)

The gas cracking system comprises the low pressure cracking unit or furnace A and the high pressure cracking unit or furnace B, and the vapor phase cracking system comprises the vaporizer C and the cracking, 'reforming andv polymerizing unit or furnace D. vThese two cracking and polymerizing systems A, B and C, D are provided with fractionating units E and F respectively, by which the cracked, reformed and polymerized materials are separated into gaseous and liquid fractions, the liquid fractions being designed f or recovery and' also for recycling Wherev desired. The gaseous fractions are connected for introduction into an absorption system G in.

which theyA may be separated into wild and stabilized gasoline and heavier normally gaseous fractions which are returned to the cracking systems A, B and C, D. This absorption system G is also shown as connected to receive and separate other gases, such as natural gas or any saturated or unsaturated reflnery gas. In order to indicate sources of suitable materials, an ordinary liquid phasecracking system H is indicated, which pro- -duces both liquids and gases, and similarly the crude distillation system K is indicated as producing both liquids and gases. The selected gases are supplied to the gas collecting and feed line I0 and the selected liquids are supplied to the liquid feed line Il.

A In connection with the operation of the process as indicated in Fig. 1. the gas for the gas cra-cking andpolymerizing unit A, B is obtained through a gas collecting and feed line I0, and the liquid material for the vapor phase cracking, re

' to' represent the usual and necessary equipment, such as stills and fractionators, to produce and separate the incident gaseous and liquid prodl ucts. The crude distillates are collected in tanks IIaconnectedto supply the liquid feed line II, and the cracked distillates are collected in tanks IIb, also connected to supply the feed line II. The normally gaseous hydrocarbons separated by the absorption system G and desired for the preswhich may be stored in tanks as indicated'or withdrawn as products. or recycled to the high pressure cracking furnace B by recycle line 2l. The bottoms will be collected, as indicated. The

gaseous and vaporous materials from the top of the fractionator wil1 be removed through line Ila, which also acts as a gas header, and may be passed in part directly to the gas recycling line I2 and in part through the cooler 25 or entirely through the cooler to produce a light Easoline" supplied by line 20 to a storage tank or draw-of! or to recycling line 24. In addition to the recycling of desired liquid products to the `high pressure furnace'B, uncracked gas may be bypassed through line 21 around furnace A,`as for purpose of adjustment of gaseous content or v temperature, and fed directly to the furnace B ent operation are collected in header I0c and de,l I

livered to the gas collecting feed line I0. This absorption system G receives gases from the gas cracking system A, lBv and the vapor phase cracking system C', D through return line I2. The wild and -stable liquid gasoline fractions recovered in the tanks I3 and I4, respectively, are connected with the liquid supply line II. In addition to the gases recycled in line I2 and the gases from the unitsH and K, other gases such as natural gases and/or other refinery gases saturated or unsaturated may be supplied through lines Id. If desired, these gases may be passed through the absorption system G or may have been already similarly prepared or otherwise prepared, if required, and introduced directly into the gas collecting and feed line I0.

In the operation of the gas cracking system A. B, the gases are pumped by one of the pumps or compressors P into the heating coils I5 of the furnace A under a pressure which may be anywhere between 0 and 100 lbs. gauge or somewhat higher, preferably between about and 50 lbs.,

and heated under this relatively low pressure to a cracking temperature between 900 and 1200 F., preferably about 1100 F. This treatment effectsV the desired low pressure cracking. In normal procedure, the cracked products leaving the coils i5 are conducted by line I8 under influence of compressor pump P into the cracking coils I1 of the higher pressure cracking and polymerizing furnace B wherein the pressure will be held at any appropriate pressure higher than that in the furnace A such as between 100 and 3000 lbs. gauge, preferably about 1500 lbs., and the temperature is between 900 and 1200 F. preferably about 1050 F., or somewhat below the temperaf along with the recycled liquidmaterlals, if desired.

In operation of the vapor phase cracking unit C, D, the liquid materials-from the liquid feed line II are passed through vaporizing coil 3 0 in the heater C at a 'temperature of about 800 F. Y

for example, and at a pressure which may be between` about 500 -and 3000 lbs. gauge, preferably about 1000 lbs.

forming and polymerizing Acoils 32 in the-furnace D where the vapors are heated to a temperature of about 900 to 1200 F. but lpreferably at about y 1025 F. under a pressure between about 500 and 3000 lbs., preferably around 700 lbs. or somewhat lower than the pressure in the vaporizer C. According to one phase of the invention only a vaporized material from the coll 30 will be treated 'in the coils! but according to another phase of they leave the furnace B, or they may be obture of the low pressure cracking furnace A. The v gases from coil I1 leave the furnace B by way of line I8. If desired, cracked gases from the furnace A may be by-passed around furnace B through line I9 into line Il or a portion of 'such gases may be so by-passed and commingled with the high pressure cracked gases leaving coil I1. In either event, the cracked gases are introduced through the line Il into the fractionating column 20 wherein the pressure is preferably reduced to about 30 lbs.v and the materials fractionated at temperatures to produce the desired liquid and gaseous products. The pressures in column 20 may range as high as 300 lbs. according to the pressure conditions intheunit A, B but preferably will bearound30to40lbs. Accordingto one method of procedure, side cuts will be taken from the fractionator 20 through lines 2|, 22 and 23 to obtain, respectively, heavy cycle stock. light cycle" stock and "heavy gasoline for example,A

tained as a mixturev of low pressure and high pressure cracked gases collected through both branches 33a and. 33h of the line 33. It is to be understood that in all cases the necessary pumps and valves and like equipment will be employed to effect the necessary passage of gases, liquids and vapors and to attain the. pressures required.y

Thus, where working at the high temperatures indicated, in order 'to raise the materials from furnace A to the ldesired pressures in'furnaces B and D, it may be necessary in practice either to cool the cracked products before they enter the compressor or to use a diaphragm pump or a surge pump using a liquid bodyv ahead of the piston as a gas-contacting medium. Or the pressure in the furnace A may be raised somewhat higher thanl above stated by the cool feed-gas pump and thereby correspondingly reduce the operating differential when such higher pressure will permit the desired effects in furnace A.

The cracked and polymerized materials leaving the coil 32 of furnace D are then passed by way of line 34 to a fractionator 25 in the unit F corresponding to the fractionator 20 in the unit E wherein the desired liquid fractions are obtained as side cuts in the form of heavy cycle," "light cycle, and fheavy gasoline," these materials bc- From coil 30. the vapor so produced is passed by line 3| to the cracking, re-

ling drawn through lines't, 37 and 38, respectively, to corresponding storage tanks or draw-ons and being also connected with a line 39 for recycling to thevinlet side of the coil 30 of vaporizer 30, Bottoms lmay be' drawn on through storage tank and/or connected through line du for recycling by way of line 39. Gases'and vapors from the top of `this fractionator 35 are drawn through line |212 which also constitutes a gas header receiving liberated gases also from the liquid side cutsthrough line 112, and'introduced in part, if desired, into'gas recycling line I2, and at least in part through cooler 43 or entirely through cooler 43.150 yield a.light gasoline liquid fraction which is passed by way of line i4 to storage or recycled, if required, through line 39.

- As indicated, allgases from the various elements of the fractionating units E and F are returned to the gas recycling line l2, and passed thence preferably through the absorption system G. Here the gases pass upward through absorber 50 against'a descendlngstream of lean absorption oil fed into the top of absorber 50 through line 5i. The dry gases leaving the top of absorber 50 will be chiefly methane containing a quantity of ethane and ethylene and any hydrogen present. According to present operating procedure, these gases are too light for satisfactory use and are vented from the system through line 52. 'I'he rich absorption oil Withdrawn from4 the bottomof absorber 5I! through line 53 is discharged into still 54 wherein the absorbed heavier constituents of the gas are distilled off, the.

thence to stabilizer 58. The stabilized gasoline is withdrawn into container i4 connected with liquid .collecting line H feeding to the vapor phasevcracking unit C, D. The wild materials from stabilizer 58 are passed through cooler 55 and the condensed constituents `are passed by line 60 to the -wild gasoline container i3 also connected with liquid feed line il. 1n order toI conserve the uncondensed gaseous materials from Cracked gases from the coil I5 may be by-passed from line i6 around furnace B and into the discharge line IB from furnace B for-'the purpose of direct fractionation of the low pressure cracked gases without subjecting them to -the high pressure operation, or for the purpose of subsequently fractionating a mixture of low pressure cracked kgases'a'nd high pressure cracked gases. y

oline, and pass through the lines 2|, 22, 23 and 26 either for separate recovery or for recycling by way of line 24 to the high Apressure cracking and polymerizing furnace B. The gases l2 are conducted to the absorption system G for separation into light dry gases which may be vented through the line 52 as previously described, and heavier normally gaseous hydrocarbons which are returned through the absorption gas manifold Ic to the primary gas feed line l0. tion system G, as here represented, is intended to be the same as that disclosed in Fig. l and in it are produced wild and, stable gasoline fractions which are respectively collected inl tanks I3 and I4 for other uses. Feed gas may be bypassed around furnace A through line 21, as for purpose of temperature control, for example, orv

, adjustment of content.

"I'hus, according to Fig. t2, various gases, but preferably unsaturated gases of the butene, propene and ethylene types, are cracked or dehydrogenated at temperatures preferably around 1100 F. and at pressures around 30-50 pounds and are then passed into the high pressure cracking and polymerizing device B where they are treated the coolers 55 and 59 and from the contauiers.

. i3, I4 and 5l suitable connections as lshown. are

made with the gas 'header lc leading to the gas collecting line iti. If desired, valved lines such as 6l and B2, may be employed for injection into gas header Ic of light fractions from the top of absorber 50 or of fractions from the top of the still 5d should it be necessary or desirable to inject any of these materials'into the Inl Figs. 2 and 3, preferred methods of prolcedure are indicated, employing the same vuni as shown in Fig. i.

Fig. 2 discloses a preferred method of cracking and polymerizing normally gaseous hydrocarbons supplied from the feed line i@ as in Fig. l. Here the gas cracking unit A, B consists of the low ,pressure cra-cking furnace A containing'the temperature conditions previously described in' connection with Fig. 1, the cracked products leavgas stream supplying the gas cracking unit A. B. K

ing the coil I'I through cracked gas line il. 75

at pressures preferably around 1500 pounds and temperatures around `0 F. to effect polymerization of the materials obtained from low pressure furnace A, the operation being also accom--l panied by isomerization of materials whereby fractions are produced which, when condensed in system E, will yield, among others, desirable liquid gasoline-like materials of high anti-knock value. This-:invention also contemplates the bypassing of gas from the low pressure cracking unit A around the unit B either for separate treatment in thefractionating system E or for commlngling with the high pressure cracked materials from coil il, in furnace B. In the latter instance where the materials are commingled, a certain amount of increased polymerizationl or desirable control may sometimes be eected as the starting materials vary.

In order to modify or control the operations in the furnace B, and sometimes in order-to produce further materials in the gasoline range, var-z tous liquids obtained from fractionating vsystem E may be recycled to the feed side of furnace B through line 2Q. Thus, by recycling of the in- `eii'ected for the productionof additional desired high .anti-knock liquids in the gasoline range.

vFor. purposes of further control, gases may be introduced directly from the feed line l0 to the furnace B by way of line-21 either with or without the recycling liquid materials. Thus, certain gases, such as propylene and butylene and sometimes propane and butane when mixed with the materials in the furnace B, are subject to direct polymerization.

Asvto the reactions in the gas cracking unit A, B, the lower pressure in furnace A fundamentally favors cracking, but we nd many activated molecules which polymerize in this zone to normally liquid materials. Similarly, the high pressure in furnace B favors polymerization of the cracked materials from furnace A, but here again we have overlapping reactions taking place at the high operating temperatures and some cracking therefore occurs in this zone also.- As a resuit both reactions take place to some extent in both zones. l

In the operations indicated in Fig. 3, reforming of gasoline-like materials entering through the feed line Il is combined with and takes place in the presence of cracked or dehydrogenated gases, or of cracked and polymerized or isomerized gases obtained from cracking unit A, B. Thus, the liquid feed stock entering through line Il passes to the vaporizing coil 30 in vaporizlng furnace C and thence by line 3| to the reforming and polymerizing coils 32 in furnace B. Gases obtained through the gas feed line I are treated in a low pressure cracking coil I5 of furnace A under conditions above described for the other figures and may be passed therefrom through line I6 into the high pressure cracking coils l1 of furnace B for polymerization and isomerization. Treated gases either from coil l5 of furnace A or from coils Il of furnace B or mixtures of these, may be passed through cracked gas line 33, including its branches 33a and lib, into the vapors passing through line Il from vaporizer C to polymerizer D. A quantity of feed gas may be by-passed to line 33 through by-pass 21. if required. In the coils 32 of the furnace D, the cracked gases from the cracking unit A, Bor from the unit A alone, undergo polymerization in the presence of the vapors from the vaporizer C which are being reformed and polymerized in the same coils.

These reactions between the two types of materials (vapors and cracked gases) taklngplace in the presence of each other result in the production of a high percentage of highly'valuable anti-knock gasoline-like materials which are passed' through the line 34 into the fractionation system F (being the same as the system F of Fig. 1), wherein the liquid materials are condensed, fractionated and separated from the gases to produce a series of cracked liquids in the form of bottoms, heavy cycle stock, light cycle stock, heavy gasoline and light gasoline which are respectively passed through lines It, 31, 38 and u, either forrecovery of the liquid materials through the -valved discharge lines shown or for recycling to the vaporizer C by way of recycling line SI. Particularly the cycle stocks and the heavy gasoline may be so recycled.

The vapors and gases delivered for recycling to the liquid feed line Il as by way of the recycling line 39.

Referring to Figs. lF and 3, itis within the scope of this invention to operate so that, instead of treating in the furnace C to effect principally vaporization or incipient cracldng, this furnace may be operated to vaporize and then produce substantial cracking or to vaporize and then form cracked materials primarily. In this manner, lthe operation in polymerizing furnace D will result in less cracking and be more distinctly a polymerizal from the fractlonating system through the manifold I2b are passed by way of gas return line I2 to the absorption system G (above described) whence they are separated into, gaseous materials returnedby way of the absorption gas manifold llc to the main 'gas feed line Il, the dry gases of the ethane or methane typepreviously described being preferably vented through the vent line 52. The liquid materials -from the absorption system G 'are Vcollected as wild and stable gasoline in the condensers I! and Il either forseparate recovery or.

.addition of saturates to unsaturates.

tion and isomerization of products produced in furnace C. Thus, it will be desirable, according to this form of the invention to use relatively high ,temperatures in the reforming or cracking zone C and preferably' lower pressures relative to the furnace D, and then in any desired. manner to cool the reaction productsproduced by the dehydrogenating and cracking reactions in zone C before vpassing them to the polymerizlng zone D. As an example, the cracking or reforming furnace C may be carried at pressures of from 500 to 1000 lbs. and 'at temperatures around 1000 to l100 F., and the polymerlzing furnace D may be carried at pressures of 1200 or 1500 lbs. up to around 3000 lbs. and at temperatures preferably someywhat 'lower than the temperatures in zone C, for

previously described, or even by introduction of gases (in gaseous or liquid form) from the gas feed line l0 by way of by-pass 21 as illustrated in Fig. 3. This addition of gases includes the addition of unsaturates to unsaturates and the Alkylation in poly-molecular reactions is increased by this concentration of the reactants.

As to the distinction between the normally gaseous hydrocarbons which are to be vented from the system and which are to be returned tothe gas cracking units, according to present operations, it is preferred to vent from the system allor substantially all of the unabsorbed gases from the absorption system, these consisting principally of the methane and a quantity of the ethane and ethylene. The remaining ethane'and ethylene do not separate from the propane, butane, propylene and butylene and pass into the absorption oil along with the heavier constituents, which find their way through the absorption oil still 54 back into the gas feed line Illc. The cut between the gases may be controlled in any desired manner by regulation of temperatures and pressures, and if quantities of the lightest materials are desired in the gas cracking system, some of these may be retained so long. as overloading with light materials is avoided by adequate venting, as will be apparent to the-skilled operator. If dehydrogenation catalysts are used, as hereinafter discussed, the volume of hydrogen to be vented will, of course, be considerable.

From the foregoing, it will be apparent that we have presented operative procedures for the conversion of various types of normally gaseous ,mide and iron bromide.

character, into normally liquid gasoline-like fractions of lhigh anti-knock value. Thereby we have not only produced materials valuable in the industry, but we have also presented a means for conserving a large quantity of they low molecular weight hydrocarbons which have heretofore found no use other than as gaseous fuel or the like. At the same time we have presented a means `for reforming liquid fractions, such as those in the gasoline range, especially in the presence of normally gaseous constituents preferably cracked and/or polymerized and/or isomerized, whereby reforming ofthe gasolinelike fractions and polymerization and isomerization of vaporous and gaseous materials take place under conditions Where such vapors and gases are in the presence of each other and the resulting liquid products obtained in commercially high percentages and have desirably highv anti-knockcharacteristics.

The invention as generally disclosed above is intended to be operated without the use of catalysts. However, as has been suggested,` catalysts may be employed in connection with the various steps. Reforming catalysts which have been found useful for this purpose are: Metals-Nickel, palladium, platinum, copper, cobalt, iron, zinc, titanium, aluminum, tungsten, molybdenum, thorium; Sulfides.-Cobalt, iron, zinc, nickel, manganese, tungsten; Oxides- Alkali metals such ascalcium, magnesium, `thorium, titanium, iron, uranium, barium, aluminum, chromium, zinc, nickel, manganese and particularly manganese peroxide, silica; Hydroazides.- Chromium, alkali metal; Acids.-Molybdic, tungstic, chromic, phosphoric, arsenious, silica, boric'; Salts.-Aluminates, chromates, tungstates, vanadates, uranates, phosphates, of the alkali earth metas such asv calcium and the alkali metals, i. e. potassium, for instance potassium chromate, dichromate, chromite and dichromite; and the phosphates, chromates and vanadates of aluminum, 'chromium or zinc; phosphates of molybdenum, tungsten; borax, ammonium mo'- lybdate, aluminum sulfate; adsorbents like fuller's earth, bentonite; Adsorbent charcoal or other adsorbent carbons; aluminum chloride, iron chloride, aluminum brocatalyst is that formed by coating alundum or absorbent clay or charcoal or silica gel withv potassium chromate and zinc sulfate, drying and heating in a stream of hydrogen. Also selenium vapors may be used.

When hydrocarbon fractions having a boiling range up to about 60o-650 F. are passed over these catalystsv at temperatures from 662-1832 F. a reforming reaction occurs. In producing gasoline containing olenic materials temperatures of about 850-1050 F. may be employed. Higher temperatures in the neighborhood of 1380-1830 F. favor aromatic formation. The salts and oxides of the difiicultly reducible metals; as for instance, the alkali metals such as calcium, magnesium, barium, require in general vhigher temperatures for the formation of olens, i. e. temperatures in the neighborhood of 1020-1380 F. The gases resulting may then be reacted in the presence of a polymerizing catalyst.

Catalysts which have been found to aid polymerization are termed polymerizing catalysts. Such catalysts are fullers-earth, absorbent carphosphoric acid in solid form, aluminum oxide,

" calcium oxide, carbonates of the alkaline metals,

' conditions.

H alides.-Such as Another appropriate V the oxides and carbonates of magnesium or beryllium, the acids of boron and antirnony, thoria, zinc chloride or aluminum chloride, cadmium phosphate, aluminum sulfate in solid form, adsorbent clays like bentonite, graphite, charcoal, copper, alkali metal salts (especially oxygen-containing salts), phosphates, borates, antimonates, boron trifluoride, either alone or as a double compound with ethylene in -the form of ethyleneiluoboric acid, cadmium. phosphate, and siliceous earths, tin, zinc, aluminum, chromium, silicon, lead or alloys of these metals.

In using the reforming and polymerizing catalysts, one skilled in the art will understand that the conventional methods of preparing catalysts of this nature are to be followed. Thus, the metals are best used when in finely divided form, and better when supported on carriers. The clays such as bentonite and fullers earth are best used in their activated states, thus fullers earth is used in the acid treated state, in which state their adsorptive activity is best brought out. Methods of increasing the adsorptive activity of,

clays and adsorbent carbon are well known in the adsorption art.

In using catalysts to be carried in the stream of gases, the catalyst, if vit is-boron fluoride, mayv lysts are solid they .are best ground fine andl carried in suspension by mixing with the liquid feed and carried along by the high velocity of the vapors. The solid catalyst may also be positioned as a contact mass in the reaction zone and the vapors passed through the body of catalyst.

Various catalysts promote one or the' other reactions, favorably, under certain temperature The temperatures and pressures herein disclosed are merely illustrative and are those at which the various reactions predominate,

but the opposite reaction, whether it be reforming or polymerization, also occurs. The temperatures are merely illustrative and are for feed stocks as herein described, and for pressures from atmospheric to 5000 lbs.

Thus, with metal catalysts, tin, zinc, copper,

aluminum, chromium, silicon, lead and nickel Lime and other alkali earths or oxides or carbonates favor polymerization in the range between 660 F. and 840 F. Magnesium and beryllium oxides favor polymerization reactions in the bon, phosphorous acids such as orthophospho- Y upper part of said range around 840 F. to 930 F. Aluminum chloride and boron triuoride are very active at temperaturesfrom 32 F. to 30D-or 390 F. Magnesium oxide, lime and silica, such as silica gel, can be used in reforming reactions in temperature ranges above 930-1290 F.V Aluminum oxide or aluminum silicate such as fullers earth or floridin or other forms will favor reforming above 750 F. Thus in using aluminum oxide, either alone or in the form of silicate, the temperature ranges should be adjusted depending on the form of the reaction which is to be favored. In operating in the upper ranges around '750 F. aluminum oxide will have a favorable influence on both reactions, aiding in the decomposition in the higher molecular Weight liquid hydrocarbons, and aiding in the lower molecular weight gaseous hydrocarbons. The temperature range should be chosen to form a balance between the two.

Of the salts or adsorbents which accelerate polymerization reaction, the alkali metal carbonates', phosphates and borates are active in the neighborhood of 'Z50-930 F.; bentonite is active from S60-840 F.; phosphoric acid is active from S50-475 F. Absorbent charcoals and carbons favor the polymerization reaction at around 750` F. Above those temperatures, and particularly at substantially higher temperatures reforming is favored by these catalysts. Calcium aluminate, ammonium molybdate favor the reforming operations at temperatures of 930-1290 F. and higher. Aluminum sulfate and phosphoric acid are active in reforming reactions above 660 F. and very active above 930 F.

Mixed catalysts composed of mixtures of any one or more of the above reforming catalysts, and any one or more of the above polymerizing catalysts, which are active, i. e. promote and accelerate the reforming and polymerizing operation in the neighborhood of '1D0-930 F. will permit of the joint and favorable reactions of re- ,forming and polymerization when operated at temperatures between about IDO-930 F. at pressures of about 'I5-1500 lbs.

A good catalyst for the polymerization reaction is aluminum oxide preferably in the form of fullers earth or artificial fullers earth formed by (zo-precipitating silica and aluminum oxide from a mixture of sodium silicate and aluminum sulfate. 'I'he aluminum silicate is washed neutral and dehydrated. It is preferred that the mixture be neutral or acid, and free of alkaline material. It is best that the catalyst be substantially fr'ee from water, dehydrated by heating, although a small percentage, up to or 6% of moisture is not detrimental. In using this catalyst .it has been found that a small amount of hydrochloric acid introduced as alkyl chloride, as for instance, isopropyl chloride may be introduced to ald the pohrmerization reaction. Ap-

' parently, the isopropyl chloride .is decomposed in the reaction zone and forms free lhydrochloric acid.

It has been found that the alkyl chlorides are conveniently formed by passing a mixture of unsaturated hydrocarbons such as butylene and propylene over the above fullers earth type catalysts as previously disclosed atv ordinary temperatures from about 20D-400 F. The alkyl chloride may be introduced either in vapor form as produced by the chlorinating reaction, or first condensed, and then introduced in liquid form.

The amount of alkyl chloride required varies from one-tenth to one per cent, preferably to about one-half percent of the reaction vapors.

The catalysts here employed may be-used in the reforming or polymerizing processes either as a catalyst body or as avmixture with incoming feed. In using the catalyst as a catalyst body, the reaction zone in the tube or chamber is charged with the solid catalyst and the reaction vapors are passed through the body of the catal range. 7o

lyst. It is possible, however, to use the catalyst as a slurry with the incoming feed, in which case the reaction zones are empty except for the reaction mixture. When the vaporized hydrocarbons carrying the catalyst ground fine in suspension pass through the reaction zone, the high velocity of the vapors and the fine particle size of the catalyst prevent sedimentation' of the catalyst in the tubes or chambers.

The foregoing description of the several modi-l cations of our invention described above are not to be considered as limiting since many variations may be made within the scope of the following claims by those skilled in the art Without departing from the spirit thereof.

We claim:

1. A method for the conversion of hydrocarbon gases and liquids into gasoline-like fractions having high anti-knock characteristics comprising subjecting a normally gaseous hydrocarbon to cracking conditions, subsequently subjecting a portion of such cracked gases to higher pressures to effect polymerization of said gases, commingling the products of said polymerization with normally liquid petroleum hydrocarbons and with the remaining portion of cracked gases, passingsaidv mixture of products of polymerization and added hydrocarbons into a heated cracking and polymerizing zone under substantial pressures and effecting reforming 'of said added hydrocarbons and polymerization of the mixed materials, and fractionating the Aproducts to yield normally liquid materials in the gasoline range.

2. A method for the conversion of hydrocarbon gases and liquids into gasoline-like fractions having anti-knock characteristics comprising subjecting a normally gaseous hydrocarbon to cracking conditions, subsequently subjecting a portion of such cracked gases to higher pressures to effect polymerization of said gases, commingling the products of said polymerization with gasoline hydrocarbons and with the remaining `portion of cracked gases, passing said mixture of products of polymerization and added hydrocarbons into a heated-cracking and polymerizing zone under substantial pressures and effecting reforming of said added hydrocarbons and polymerization of the mixed materials, and fractionating the products to yield normally liquid materials in the gasoline range.

3. A method for the conversion of hydrocarbon gases and liquids into gasoline-like fractions having high anti-knock characteristics comprising subjecting a normally gaseous hydrocarbon to cracking at temperatures in the neighborhood of G-1100" F., subsequently subjecting a portion of such cracked gases to higher pressures to effect polymerization of' said gases, commingling the products of said polymerization with nor- 4mally liquid petroleum hydrocarbons and with ROBERT E. HAYmrr'r. EARLE W. GARD. PHILIP sUBKoW.

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