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Publication numberUS2658858 A
Publication typeGrant
Publication dateNov 10, 1953
Filing dateJun 22, 1949
Priority dateJun 22, 1949
Publication numberUS 2658858 A, US 2658858A, US-A-2658858, US2658858 A, US2658858A
InventorsCarlos L Gutzeit, William H Lang, William A Stover
Original AssigneeSocony Vacuum Oil Co Inc
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Aromatization reforming and catalysts for effecting the same
US 2658858 A
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Description  (OCR text may contain errors)

Nov. 10, 1953 H LANG ET AL W. AROMATIZATION REFORMING AND CATALYSTS F'OR EFFECTING THE SAME Filed June 22, 1949 2 Sheets-Sheet l ONK ATTORNEY Nov. 10, 1953 w, H, LANG ET AL 2,658,858

AROMATIZATION REFORMING AND CATALYSTS FOR EFFECTING THE SAME Filed June 22, 1949 2 Sheets-Sheet 2 500 fMPf/P/m/RE, ac if?" 4 .00 r/f-MPf/mn/RE, "c

ATTORNEY Patented Nov. l0, 1953 AROMATIZATION REFORMING AND CATA- LYSTS FOR EFFECTING THE SAME William H. Lang, William A. Stover, and Carlos L. Gutzeit, Woodbury, N. J., assgnors to Socony-Vacuum Oil Com corporation of New York pany, Incorporated, a

` Application June 22, 1949, 'serial No. 100,562

4 Claims. s l

This invention relates to new catalysts containing chromium oxide and oxides of metals of the iron group, and to a process for effecting the aromatization of aromatizable hydrocarbons. It is more particularly concerned with new catalysts of the type referred to prepared under conditions adapted to form mixed oxides which have a speciiic activity for the dehydro-cyclization of normal parafns.

Aromatization is a term well known in the art and connotes the selective conversion of parafn nic, olenic or naphthenic hydrocarbons, containing at least six carbon atoms per molecule, generally referred to as aromatizable hydrocarbons, into aromatic hydrocarbons having the same number of carbon atoms per molecule. The formation of aromatic hydrocarbons by condensation of monoolefinic, diolenic or acetylenic hydrocarbons, through homopolymerization or copolymerization, is not included within the accepted meaning of the term. Aromatization may involve one reaction or two separate and distinct reactions, depending upon the nature of the aromatizable hydrocarbon which is subject ed to the treatment. When aromatizable paraffinie or olenic hydrocarbons are the hydrocab bons to be aromatized, the reactions which must occur to produce an aromatic ring are dehydrogenation and cyclization. These reactions are collectively referred to, in the art, as dehydro- Y cyclization. On the other hand, when aromatizable alicyclic hydrocarbons are the hydrocarbons to be aromatized, dehydrogcnaton is the only reaction that must take place.

As is well known to those familiar with the art, unsaturated hydrocarbons, as a class, possess octane number ratings that are higher than those of the corresponding saturated hydrocarbons, and aromatic hydrocarbons, as a class, possess octane number ratings that are higher thanl those of aliphatic and naphthenic or alicyclic hydrocarbons, saturated and unsaturated, although the octane number ratings of `certain individual aliphatic hydrocarbons are as high or even higher. Therefore, aromatization is an expedient whereby the aromatizable lowfoctane aliphatic or alicyclic hydrocarbons can be con# Verted into the corresponding but higher-octane aromatic hydrocarbons. Aromatization, of course, is not only applicable to the treatment of individual aromatizable hydrocarbons, but also, to the treatment of mixtures of aromatizable hydrocarbons. Such operations are referred to as aromatization reforming, and the conditions of temperature, pressure, and residence time are referred to as aromatization reforming conditions.

-The hydrocarbon mixtures which are subjected to aromatization reforming may contain, and generally do contain, non-aromatizable hydrocarbon constituents. Typical of these hydrocarbon mixtures are petroleum naphthas. As a result of the aromatization reforming operation, the aromatizable hydrocarbon components of the mixtures are converted into the corresponding but ordinarily higher-octane aromatic. hydrocarbons, while the non-aromatizable hydrocarbon components are dehydrogenated to the corresponding higher-octane unsaturated hydro'- carbons, as stated hereinbefore. In Viewof the ever-increasing demand for higher-octane fuels, the utility and advantages of -a commercially feasible process for effecting aromatization re-I forming are manifest. Y

Accordingly, several aromatization reforming processes have bee-n proposed. Thus; it has been suggested to treat petroleum oils, under aromatization reforming conditions, in the presence of catalysts containing iron oxide or chromium 0X- ide as the active constituent. In the processes utilizing catalysts containing chromium oxide as an active constituent, the catalyst-poisoning effect of traces of iron has been recognized and this has led to the proposal of numerous methods to prevent the'contamination' of" such catalysts by iron. These methods include the use of nonferrous metals as liners for reactors and sulfurpoisoning of ferrous metals to avoid migration of iron froml the reactor Walls to the catalyst.V

In catalytic hydrogenation and dehydrogen'a tion processes, chromites of metals of theiron group, i. e., iron, nickel and. cobalt, such as Fe(C'rO2)2, are Imilder catalysts than chromium oxide or the metals of the iron group per se from which these chromites may be considered to be derived. This milder catalytic action is exemf plied by the formation of methanol vand other oxygen ,organic compounds obtained when ca`r' bon monoxide and hydrogen are allowed to react v in the presence of these chromite catalysts. When carbon monoxide and hydrogen are allowed tov react in the presence of a metal of the iron group per se, under the same reaction conditions,"l

methane, rather than methanol, is produced. The milder catalytic activity of these chromites has led to their use in the selective desulfuriza-l tion of sulfur-containing petroleum oils under hydrogen pressure and as catalysts in aromatig` zation reforming operations. Thus, for example, U. S. Patent Nos. 2,315,144; 2,325,034; l2,393,288; 2,398,919 and 2,409,587 disclose processes for ef# fecting reforming and desulfurization of hydrocarbon fractions through the use of molybdates and chromites of metals of the iron group as catalysts. The latter are prepared by precipita# tion of normal salts of molybdic or chromic acid by a simple metathetical reaction. This limits the composition of the catalytically active mau terials to ratios of molybdenum or chromium to iron group metal which will react in aqueous solutiorr izo-formv insoluble productsof xed com'- position..

The definition of metal chromite catalysts is controversial. It is based normally upon the method of preparing mildly active hydrogenation catalysts effective in the production of. roxygencontaining compounds, such as alcohols, as' de'- scribed in U. S. Patent' Nos. ,1,745,782 and 1,746,783. The preparation. involves` l.the exothermic decomposition of water-insoluble, priecipitated double salts of hexavalent chromium and a hydrogenating metal Whichmay bean iron group metal. The preparation of' such catalysts has been discussed in detail by Calingaert land. Edgar, Ind. Eng. Chem., 26, 878 (1934) and by rdlsins Reactions of Hydrogen with Organic onrpounds over Copper-Chromium Oxide and Nickel- Catalysts, The University of Wisconsin Press j61937,). It Yshould be noted;I however, that catalysts equal in activity to those described in U. S; `Patent Nos, VLil-4:61782 and 1,746,783, 'have been obtained `by precipitation .of mixed copper and Vvchromium salts with ammonium carbonate -Iseeonnen Folkers and Adkins', J. Ghem. Soc., l53, 2012 (193ML It should be noted also that' while the methodof chromite forma-.tionset forth in these two patents is satisfactory'for the preparation of vcopper or zinc .chromitea which are those usually prepared by this method; it is dlmculit to prepare iron chromi-te in this manner.

While the vnature of chromite catalysts-such as copper chromite is the subject of controversy, the chromites are recognized by crystallographers as a-type of spinel andare defined by their composition andcrystal ,arrangement [see Wyckoff, The Structure of Crystals, The Chemical Catalog Co. (1931 et seqJl. There is no literature relating catalytic activity to structure of wellcrystallized spinels.

suitably combined, intimate mixtures of .iron oxide and chromium oxide, prepared in a manner to avoid chr-omite formation, have been disclosed as dehydrogenation catalysts to effect the dehydrogenation .off butylenes to butadiene in a continuous operation. For instance, in U. S. Paten-t No. 2,408,140, it has been proposed to prepare a catalyst effective in the .dehydrogenation of butylenesto butadiene by calcining a mixture of pigment-grade iron. oxide, commercial chromic oxide anda potassium salt.. Mechanical mixtures of these metal oxides, prepared from them in the dry state, however, are not effective as cata.- lysts in aromatization reforming. For example. a catalyst thus prepared will not catalyze the eromatization `of n-heptane, a hydrocarbon which is generally used in the evaluation of .aromatization reforming catalysts.

It has now been `discovered that it is possible to effect .the aromatization of aromatizable hydrocarbons and to carry out aromatization reformlng .of hydrocarbon mixtures containing aromatizable hydrocarbons in the presence of mixtures of chromium oxide with oxides of metals of the iron group. As stated hereinbefore, .aromatization catalysts, the active constituent of which is chromium oxide, are fairly active catalysts and appreciably more effective, as aromatization catalysts, than catalysts the active constituent of which is iron oxide. However, it has now been found that when iron oxide is mixed with specie,

fied amounts of chromium oxide, in the hydrated oxide state and under conditions to avoid chromite formation, the aromatization activity of the mixtures is greater than either constituent alone. Also, it has been found that the mixtures .of metal 4 oxides whichV are effective asy aromatica-tion reforming catalysts herein, are: also leffective as desulfurization catalysts.

Accordingly, it is an object of the present invention to. provide anovel and eilcient aromatization 'and aromatization reforming process. Another object is to provide an eicient and commercially feasible catalytic aromatization reforming process. A further object is to provide a novel catalytic aromatization reforming process utilizing certain Amixtures of chromium oxide with iron oxide, as a catalyst. A specific object is to provide new catalysts containing chromium oxtdeandv oxides of metals of the iron group. An important object is to provide a process for producing vnew catalysts containing chromium oxide and oxides of metals ofthe iron group.

Other 4robjects and advantages of the present invention will become obvious to those skilled' in the art from .the oliowing description taken in conjunction with the; drawings, in which:

Figure 1. shows two curvesrepresenting gra-phically the relationship between the conversionof n-heptane into toluene, under aromati-zatiorr'reaction conditions, and in the presenceof the catalysts contemplated herein, vand. the concentration of iron oxide in the catalysts.;

Figure 2 showsr two curves representing graphically the relationship between lthe ratio of toluene to catalyst per hour in the conversion ofnheptane to toluene, under aromatization reaction conditions and in the presence of the catalysts contemplated herein, and the yconcentration of iron oxide in the catalysts;

Figure 3 shows a vseries of curves indicating graphically the effect of temperature and duration of run on the dehydrocyclization of n-heptane with the catalysts of the present invention;

Figure 4 shows a curve indicating graphically the eiect of temperature on the `conversion of nheptane to toluene in accordance with the present invention; and

Figure 5 shows a curve indicating graphically the eiect of temperature on the rate of toluene ,y formation from n-heptane, in accordance with the present invention.

Broadly stated, the present invention provides:

.1. A catalyst comprising intimate mixtures of chromium oxide with specified amounts of oxides of metals .of the iron group, prepared from the moist, undried hydrous oxides, calcined at specified temperatures and under conditions to prevent chromite formation 2. A process for desulfurizing sulfur-bearing hydrocarbon fractions, which comprises contacting a sulfur-bearing hydrocarbon fraction, in the presence of hydrogen, under aromatization reforming conditions, with one of the aforesaid catalysts; and

3. A process for eiecting the aromatization of aromatizable hydrocarbons or the aromatization reforming of hydrocarbon mixtures containing aromatizable hydrocarbons, which comprises contacting said hydrocarbons, under aromatication reforming conditions, with one of the aforesaid catalysts.

In accordance with the present invention, the aromatization, aromatization reforming and desulfurization catalysts to be employed herein are intimate mixtures of an oxide or oxides of metals of the iron group with a chromium oxide. It is appreciated that these metal oxides exhibit varying states of oxidation. Thus, the term oxide of a metal of the iron group embraces ferrous oxide (FeO), ferrosoferric oxide (FesOi), ferric to determineY and are not known at present.

Nevertheless, whatever these states may be, the successful accomplishment of the desired conversions in accordance with this invention, would seem to indicate that these states are achieved and maintained under the reaction conditions of l the process contemplated herein, independently of the states of oxidation of the metals in the starting catalyst. Accordingly, and in the interest of brevity, the various oxides of the metals of the iron group and the various chromium f;

oxides will be referred to hereinafter and in the claims, as iron group metal oxides and chromium oxide, respectively, it being clearly understood that when reference is made thereto, one or more of these iron group metal oxides or chromium oxides will be intended.

, While it is not possible to specify the active states of oxidation of the component metal oxides during reaction, it is possible to do so for the metal oxides in the initial catalyst preparations contemplated herein. It has been found that the state of oxidation in the initial catalyst preparations must be such as to eifect miscibility of the metal oxides in all proportions, i. e., form solid solutions in all proportions. The solid solution formation may occur during the initial heat treatment. l In accordance with the rule established by Passerini [Gaza chim. ital., 62, 85 (1932)] concerning solid solution formation between isomorphous metal oxides in which the metals have the same valence, iron oxide, for example, and chromium oxide form solid solutions in all proportions only if they correspond to alpha-ferric oxide and ordinary chromic oxide, respectively. Both these oxides crystallize as rhombohedral crystals which are isomorphous. The rule established by Passerini states:

' (a) The metal oxides are miscible in all proportions if the ionic radii of the metals do not diifer by more than 12 per cent;

- (b) The metal oxides are partially miscible if the ionic radii of the metals diifer by more than 12 per cent but less than 30 per cent. In such cases, there are two regions of miscibility (one stable phase) separated by a miscibility gap representing two stable phases of solid solutions each of which corresponds to a limiting solubility concentration;

(c) Solid solution does not occur if the ionic radii of the metals differ by more than per cent.

Accordingly, the active metal oxides in the initial catalyst preparations of the present invention correspond to subdivision (a) of the rule, While the initial states of oxidation of the coprecipitated chromic oxide-alumina catalysts of U. S. Patent Nos. 2,249,337; 2,258,111;Y and 2,363,498 and of the coprecipitated ferric oxide- S alumina catalysts of U. S. Patent No. 2,449,295 correspond to subdivision (b) of the rule.

As stated hereinbefore, chromium oxide or iron oxide, per se, possess aromatization catalytic action. However, and also as stated hereinbefore, the avoidance of contamination of chromium oxide aromatization catalysts by iron is well established. Thus, for example, the presence of iron oxide in chromium oxide catalysts, otherwise prepared in accordance with the present invention, in amounts of up to about 20 mol per cent, in terms of the sesquioxides (Fe203 and CrzOa), appreciably reduces the aromatization catalytic activity of the chromium oxide. However, larger amounts appreciably increase the aromatization catalytic activity of the chromium oxide. On the other hand, when the amounts are in excess of mol per cent, in terms of the sesquioxides, the aromatization catalytic activity of the chromium oxide is again materially reduced. Because of these facts, the ratio of iron group metal oxides to chromium oxide, in the catalysts to be used in the process of this invention, is very critical. This is illustrated in Figures 1 and 2 of the drawings. The data for these curves were obtained as set forth in Example 1, described hereinafter.

It will be noted that the addition of relatively small amounts of iron oxide to chromium oxide produces a decrease in catalytic activity. This is in complete accord with the prior art. However, at higher concentrations of iron oxide in the iron oxide-chromium oxide mixtures, within the range of mol per cent ratios corresponding to Fe2O3zCr2O3: about 30:70 to about '70:30, the iron oxide-chromium oxide mixtures are equal or superior to either chromium oxide or iron oxide.

Therefore, with respect to composition of the catalytically active metal oxides, the catalysts of the present invention may be dened as intimate mixtures of chromium oxide with iron group metal oxides in which the mol per cent ratios, expressed on the basis of the metal sesquioxides, are Cr2O3:M2O3::between about 35:65 and about :30, wherein M represents the iron group metal or metals. The preferred compositions correspond to mol per cent ratios of CrzOszMzOa: :between about 40:60 and about 70:30. It must be clearly understood that the expression of the mol ratios in terms of the metal sesquioxides is only a convenient way for indicating substitution of atomic equivalents of one metal for another and does not necessarily represent the catalytically active forms of the metal oxides.

The catalytically active iron group metal oxide-chrominum oxide mixtures to be used herein may be produced by any of the well known methods utilized in the preparation of active metal oxide mixtures from the hydrous oxides, such as by coprecipitation, ccgelation or separate precipitation and wet mixing of the hydrous'oxides, or, in general, by any method providing an intimate contact between the hydrous oxides of iron group metal and chromium, collectively referred to herein as intimate mixtures of the metal oxides prepared from the moist, undried hydrous oxides. In accordance with the present invention, it is essential that the catalysts be prepared from hydrous oxides. Accordingly, the catalysts contemplated herein are prepared, as is well known in the art, by:

(a) Coprecipitation of hydrous oxides or of other compounds which decompose to form solely an intimate mixture of active metal oxides under conditions of calcination; cr

(b) Coprecipitation of hydrous oxides or-of other 'compounds under conditions of calcination to form solely metal oxides, these metal oxides comprising the catalytically active metal oxides as well as substantially inert, refractory metal oxides which serve as spacers for the active metal oxide particles, thereby decreasing sintering or crystallization; or

(c) Impregnation of substantially inert, refractory metal oxide supports with true aqueous solutions, such solutions being selected to avoid hydrolysis or other decomposition during the impregnation step but which decompose under conditions of calcination to leave a residue which consists solely of an intimate mixture of the catalytically active metal oxides.

Typical of the compounds from Which the catalysts may be prepared are the water-soluble metal salts the anions of which are decomposed by vheat and oxidation, for example, theiron, nickel, cobalt or chromium nitrates or acetates. Sulfates may be used also except when a twostep precipitation is employed in which a sol is initially produced at a pH value of below '7. A small amount of sulfate ions on the catalyst surface, such as that which remains after rapid precipitation at a pH value above 7 or by Washing the hydrated oxides precipitated from nitrates or acetates with ammonium sulfate, is highly desirable because it decreases coke deposition on the catalyst during utilization in the aromatization or aromatization reforming or desulfurizaticn process. Nonvolatile anions such as chlorides are preferably absent. Precipitation may be effected by ammonium, potassium or sodium hydroxides and/or their carbonates. The hydroxides can be used to effect either slow or rapid precipitation of the iron group metal and/or chromium hydroxides. The carbonates may be employed only when rapid precipitation is desired. It will be noted from the foregoing that the catalysts of the present invention differ from those described in U. S. Patent Nos. 2,315,144; 2,325,034; 2,393,288; 2,398,919 and 2,409,587 in that the conditions involved in their preparation preclude the formation of normal salts between the catalytically active components of the catalysts and also avoid the formation of well-defined crystals between the catalytically active metal oxides.

Whether the hydrous oxides or metal hydroxides have been coprecipitated or cogelled or precipitated separately and then mixed While Wet, these materials are subsequently dehydrated by, for example, heating at a suitable temperature v[about 70 C. (160 F.) to about 110 C. (230 FJ] to produce the corresponding mixtures of iron group metal and chromium oxides. The resulting mass is subsequently comminuted and then calcined at temperatures falling within the range varying between about 350 C. (662 F.) and about 600 C. (1112 F.) and, preferably, between about 500 C. (932 F.) and about 600 C. (l112 F.), for about to about 10 hours, under conditions such that chromite formation does not occur, i. e., under conditions such that the chromium is not oxidized to the hexavalent form. Such calcination, as is well known in the art, is effected in a current of hydrogen, carbon dioxide, steam, nitrogen, or mixtures thereof. It may be carried out in a. current of air or oxygen-containing gases provided that the catalysts contain organic materials such as starch or organic lubricants for pelleting, such as stearin.

In view of the foregoing, it will be noted that the catalysts contemplated herein are different from those described in U. S. Patent No. 2,408,- 140 in at least one very important respect, viz., the temperature of calcination. While high temperature calcination does not lead to chromite formation, it nevertheless causes recrystallization [see Milligan and Merten, J. Phys. and Colloid Chem., 51, 521 {1947)l. The deleterious eifect of high temperature calcination on the dehydrocyclization activity of the catalysts of the present invention is illustrated by Example 2 set forth hereinafter.

The catalytically active mixtures of iron group metal oxides with chromium oxide may be used alone or in conjunction with substantially inert, from a dehydrocyclization catalytic activity standpoint, refractory oxides such as alumina, beryllia, titania or zirconia. These materials serve as spacers for the catalytically active oxides and, also, as stabilizers against crystallization and loss of structure. lSilica is preferably absent because it tends to decrease the selectivity of the catalysts contemplated herein, although small amounts, the cracking action of which has been suppressed, such as that which occurs in calcined bauxite, may be employed.

These refractory oxides may constitute a major or a minor proportion of the catalyst. The amounts ci refractory oxides used are not critical and, ordinarily, depend upon the iron group metal oxide present in the catalyst and upon the manner in which the catalyst is prepared. For example, when the catalysts are prepared by coprecipitation, the substantially inert refractory oxides may comprise from about 30 to about 70 mol per cent of the total oxides in the catalyst. It has been found that the preferred concentration of the refractory metal oxide increases in the order iron oxide-chromium oxide, cobalt oxide-chrominum oxide, nickel oxide-chromium oxide as the active components, in the vorder given. The preferred amount for the iron oxidecontaining catalysts is about 30 to about 50 mol per cent; the preferred amount for the nickel oxide-containing catalysts is about 50 to about 70 mol per cent. On the other hand, when the catalysts are prepared by impregnation, the refractory metal oxide support may comprise from about to about 95 mol per cent of the total mixed oxides, and, preferably, from about to about mol per cent. Accordingly, in this specification and in the claims the expression consisting essentially of is not to be construed as excluding such substantially inert refractory oxides which do not aiect the catalytic properties of the catalysts of the present invention.

The desirability of incorporating a substantially inert refractory metal oxide in the catalysts to prevent sintering, illustrated by examples set forth hereinafter, is substantiated by Milligan and Merten, J. Phys. and Colloid Chem. 51, 521 (1947). These authors have shown that ferrie oXide-chromic oxide mixtures tend to crystallize at 400 C, or higher. While the catalytically active materials of this invention probably do not correspond to simple mixtures of ferrie oxide and chrornic oxide, it is probable that certain stages of oxidation and reduction associated with catalyst regeneration by oxidation correspond to such relatively unstable ferrie oxide-chromic oxide mixtures.

The supported catalytic mixtures of the present invention are prepared in accordance with any of the well known procedures. For example, the hydrous oxides from which the catalytically active oxides are obtained may be precipitated in the presence of the support or supports or the latter may be impregnated with salts of the metals which, upon calcination, decompose to form the catalytically active metal oxides. The catalyst supports may also be incorporated by coprecipitation, cogelation or separate precipitation and wet mixing with the active metal oxides, as is well understood in the art.

The catalysts may also contain promoters to control and to stabilize the catalytic activity of the iron group metal oxide-chromium oxide mixture. Suitable promoters are the oxides of potassium, sodium, rubidium, cesium, copper, silver, gold, calcium, strontium or barium, or compounds of these metals which yield the corresponding oxides upon calcination, such as the nitrates, acetates and sulfates. The amount of promoter should be at least about 0.2 per cent by weight, in terms of the oxide, and, preferably, is somewhat higher, for example, between about 0.5 per cent and about per cent by weight. If desired, a mixture of two or more p-romoters may be utilized.

The promoter may be incorporated in the catalyst in accordance with any of the well establishedmethods known in the art. For example, the hydrous` oxides from which the catalytically active oxides are obtained may be precipitated in the presence of salts of the metals which yield the metal oxide promoters, or the catalyst supports may be impregnated with salts of the metals which, upon calcination, decompose to form the catalytically active metal oxides and promoters. The promoters may also be incorporated by coprecipitation, cogelation or separate precipitation and wet mixing with the catalytically active metal oxides.

The catalysts may be used in any of the conventional forms such as powder, pills, spheres, extrudates or irregular fragments, all of a size adapted for the reaction system to be employed. The catalysts may be used in onstream periods of minutes to 5 hours or more, depending upon the reaction conditions of the process.

In operation, the catalysts become fouled with carbonaceous material which ultimately aifects their catalytic activity. Accordingly, when theV efficiency of the catalyst declines to a point where further operation becomes uneconomical, or disadvantageous from a practical standpoint, the catalyst may be regenerated, asis well ,known in the art, by subjecting the same toa careful oxidation treatment, for example, by passing a stream of air, oxygen, steam, or mixtures thereof over the catalyst under appropriate temperature conditions Vand for a suitable period of time, such Vas the same period of time as that ofthe catalytic operation. Preferably, the'oxidation treatment is followed by a purging treatment, such as passing over the catalyst a stream of purge gas, for example, nitrogen, carbon dioxide, or the like.

Any aromatizable hydrocarbon or mixture of aromatizable hydrocarbons is suitable as the hydrocarbon reactant in the process of this invention. The hydrocarbon mixture may contain non aromatizable hydrocarbons. Sources of theseA hydrocarbon feed stocks are petroleum naphthas, particularly those having a boiling range of from about 70 C. to about 230'C. (125- 450F.).

, The reaction or contact time, that is, the period of time during which a unit volume of the reactants is Vin contact with a unit volume of catalyst, may vary between a fraction4 of a second and several minutes. Thus, the apparent 10 contact time may be as low as 10 seconds and as high as 20 minutes. It must be realized that these iigures are at best estimates based on a number of assumptions. For all practical purposes, as in catalytic processes of the type of the present invention, the more reliable data on contact time is best expressed, as is well known in the art, in terms of liquid hourly space velocities (L. H. S. VJ, in the present instance, the volume of liquid hydrocarbon reactant per volume of catalyst per hour. For example, at atmospheric pressure, it has been found that the space velocities may be varied considerably and that velocities varying between about 0.2 and about 2.5 are quite satisfactory for the purposes of the present invention.

In general, the temperatures to be used-in this process vary between about 450 C. (840 F.) and about 650 C. (1200 F.) and the hydrocarbon vapor pressures employed are low,- of the order of 30 pounds per square inch or less. These ranges of variation of the reaction conditions are inclusive of the following operations:

(a) Low pressure operation in the absence of diluents at temperatures of about 450 C. (842 F.) to about 600 C. (1112 F.), preferably about 485 C. (905 F.) to about 550 C. (1022 F.), at liquid hourly space velocities of about 0.2 to about 2.0, preferably, about 0.5 to about 1.0, and a total pressure of not over about 30 pounds per square inch gauge;

(b) Moderate pressure operation in the presence of hydrogen to effect desulfurization, as Well as aromatization reforming, at temperatures of about450 C. (842 F.) to about 600 C. (1112" F`.). at liquid hourly space velocities of about 0.2 to about 2.0, at hydrocarbon partial pressures of not over about 30 pounds per square inch gauge, at total pressures of from about 0 to about 300 pounds per square inch gauge, with hydrogen to hydrocarbon mol ratios varying between about 1:1 to about 10:1. Preferred conditions are temperatures of about 485 C. (905 F.) to about 550 C. (10.22 FJ, liquid hourly space velocities of about 0.2 to about 0.5, total pressures of about 50 to about 150 pounds per square inch gauge, and hydrogen to hydrocarbon mol ratios varying between about 1:1 and about 5:1. The hydrogen vdilution may be effected suitably by recycle of the hydrogen-rich gases from the process; and

(c) Low pressure operation in the presence of steam attemperatures of about 500 C. (932 F.) to about 650 C; ('1202 FJ, preferably, about 550gC. (1022 F.) to about 600 C. '(1112" FL),V

liquid hourly Aspace velocities vof liydro'carbo'n` charge of about 0.2 to about 2.5, preferably, about 0.5 to about 1.0, total pressures of not over about 50 pounds per square inch gauge,v preferably not Vover about 30 pounds per square inch gauge, with the addition of steam ineamounts to produce steam to hydrocarbon mol ratios varying from v about 1:1 to about 1:6, preferably from about 1:2 Y

to about 1:4. r

. The present process may be carried out by mak- Y ing use of any of the well known techniques for operating catalytic reactions in thevapor phase y effectively. The reaction zone may be a cham-1 ber of any suitable type useful in contact-catalytic operations; for example, a catalyst bed contained in a shell, or a shell through which the `catalyst flows concurrently, or countercurrently, with the reactants.

mined `period of time, both as set forth hereinbe- The hydrocarbonvapors are main-` Y tained in contact withV the catalyst at a predetermined elevatedtemperature and for a predeterfore, .and the resulting reaction mixture is passed through a condensing zone into a receiving chamber. It will be understood that when the catalyst iiows concurrently, or countercurrently, with the reactants in the reaction chamber, the catalyst Will be thereafter suitably separated fromfthe reaction mixture by ltration or the like.

It will be apparent that the process may be operated as a batch or discontinuous process as by using the catalyst-bed-type reaction chamber in which the catalytic and regeneration operations alternate. With a series of such reaction chambers, it Will be seen that as the catalytic operation is taking place in one or more of the reaction chambers, regeneration of the catalyst can be taking place in one or more of the other reaction chambers.Y Correspondingly, the process may be continuous when one or more catalyst chambers are used through which the catalyst iioWs in contact with the reactants. In such a continuous process, the catalyst will flow through the reaction zone in contact with the reactants and will thereafter be separated from the reaction mixyture as, for example, by accumulating the catalyst on a suitable lter medium, before condensing .thereaction mixture. In a continuous process, therefore, the catalyst-fresh or regenerated- .and thereactants-ffresh or recycledf-will continuously flow through a reaction chamber.

.The following A,detailed examples are for the d intention.. It must be clearly understood, howover. that the invention is notl tobe construed as limited to the specilic catalysts, manner of preparing them, and hydrocarbon reactants disclosed hereinafter or to the specific manipulations and conditions. set. forth in the examples. .In each test, the hydrocarbon reactant was contacted with the catalyst in a conventional isothermal reactor. Analyses of liquid products were made by means '.Q, refractive index and mass spectrometry in the case o nfheptane conversions, and by means of Standardmethods for the determination of aro matic. content and of octane number in the case ofllaphtha conversions. All .gas analysis .were iliade by mass spectrometry. Brominenumbers refer t0. the Standard Norwood .bromine number values. v a

'EFFECT or Irion oxipn on neoiurcii'xip'u: jjiioriynriou Foa THE DEnrDBoocYcLizA'rioN oil: n- HErrANE" f *Catalyst preparation-These catalysts were preparedv by rapid precipitation of"mixed"metal Aoxide sols,- using starch for the clual'purposev of stabilizing the initial sol and ofminimizing oxidaj tion Vof thechromium during ealcination of the dried products. The method is illustratedby the preparation ofY a catalyst initially corresponding toFezOazCr2O3=40z60 (mol-ratio).

Al-stock rsolution was prepared containing 0.6 mol CrtNO'a) a, 0.4 mol Fe(NO3)3 and 50g. soluble starch perliter. For each liter of this stock solution, there was added, with vigorous stirring, lone literof `a 2.4.molar solution of NI-IiGI-I to obtain 8d per cent neutralization of` the metalsalts, the addition being. controlled to lprevent formation of a permanent precipitate.. The product was a sol oi mielimetnloxides stabilizedby the remaining Hl'll. and bythe starch. `This sol was rapidly precipitated with an approximately equal vol#- ume of 0.3 molar NI-IiOl-I by continuous introduction of a thin stream of each solution into the upper part of a mixing chamber, the greater part of which was lled by a rapidly rotating, slotted, metal cylinder. The slurry of metal oxides so formed was allowed to now by gravity into a glass chamber containing glass and calomel electrodes connected to a pH meter. The rates of addition of the reactant streams to the mixing chamber were adjusted to producev a slurry at a pH of 8.0i0.05, and the product which formed at this pH was collected. After aging for 24 hours, the precipitate was iiltered oi and Water-washed until the wash water showed a negative test for nitrate ions with diphenylaminefsulfuric acid in.- dicator. The precipitate was then dried at C. to C. in an air-circulation drying oven for about 18 hours, then heated slowly in a muiiie furnace over an 8-hour period to 500 C. and maintained at this nal temperature for 4 hours.

Catalysts containing chromium oxide alone and iron oxide alone were prepared similarly from chromic nitrate and from ferric nitrate, respectively. The remaining catalysts were prepared similarly from stock solutions containing chromic nitrate and ferrie nitrate n the ratios required to give the desired ratios of metal oxides in the products. In each case the initial stock solution contained total metal nitrates equivalent to a 1.0 molar trivalent metal nitrate solution.

Catalyst evaluation-The evaluation of these catalysts for n-heptane dehydrocyclization is summarized in Table I and the more important results are shown graphically in Figures 1 and 2,. It will be observed that the coprecipitation of small amounts of iron oxide with the chromium oxide causes a drop in the activity for dehydrocyclization. However, incorporation of relatively large amounts of iron oxide in the catalysts results in an increase in dehydrocyclization actvity such that Within the range of composition, expressed as mol ratio of the sesquioxides, of FezOszCrzOs or 30:70 to 70 :30 the dehydrocyclization activity iS.. greater than that of chromium .oxide alone.

Table I .-Dehydrocyclization of n-heptane; effect of iron oxide on chromium oxide [500 C., atmospheric pressure, L. H. S. V.=l, 5-hr. tests] Initial catalyst composition, Number of Av. toluene *igilllve Q5 galf mole percent catalyst in liquid time tgp r gngt reuesra' wgroduct t toluene, pfatalyst l CHOl Feaos um i pern wt. percent per hour 100 0 22 l5. 5 0. 7 100' 0 l 20. 5 14. 5 65 90 10 0 11 10. 5 0. 6 90 10 1 7 7 0. 4 gi.) 11 589. 5 g. 5 o. f5 5, 45 'Z0 30 Q 24. 5 22. 5 1A. 35 70 30 Y l 20 18. 5 1. 1 eo 4o o ,30. s 2,8 1.65l 60 40 1 25 24. 5 1. 45 50- 50 0 27 24. 5 1. 45 50 5or i 25 2,3. 5 1.1i 3U 70 0 14. 5 14 0. 85 30 70 1 14. 5 13. 5 0. 8' y o 10u o 3 3 dos o ico i i. s 1, 5 o. 0,45

This method of catalyst preparation is limited to the use of metal salts, of monovalent anions which are decomposed completely during calcination. Such salts are nitrates and soluble organic salts Ysuch as acetates. Sulfates do. not produce a satis- 13 factory sol unless the starch concentrations are made very high. The nal catalysts so obtained, containing large amounts of sulfate ions, are of low activity. Chlorides cannot be used because the small amounts of chloride remaining in the catalysts act as serious catalyst poisons. Similarly, the precipitants are limited to ammonium hydroxide, sodium hydroxide and potassium hydroxide. Ammonium hydroxide is preferred be` cause the ammonium ion is destroyed by calcina-r tion. Alkali oarbonates cannot be used.

Other carbohydrates and polyalcohols may be substituted for the starch, such as glucose, cane sugar, or glycerol. Starch is preferred because it do'es not form a true solution in water and hence is not removed during the water-washing step. Consequently, the addition of starch provides a simple and easily controlled method not only for stabilization of the initial metal oxide sol but for prevention of oxidation of the chromium to hexavalent chromium during the calcination. Starch concentrations from about 25 grams to 200 grams per mol mixed metal nitrates in the initial stock solution may be used.

The concentration of metal salts in the initial stock solution my be varied from amout 2 molar to 0.2 molar. The high concentrations are somewhat diiicult to handle because of the high concentration of solids in the final slurry. The veri7 low concentrations are inconvenient becauseof the large volumes of solution which must be handled.

EXAMPLE V2 Y EFFECT or HEAT TREATMENT oN IRON OXIDE- I CHROMIUM OxIDE CATALYsTs Catalyst preparation-#Five catalysts were pre, pared.v The rst'three catalystsl are partof a singlepreparation made similarly to the catalysts in Example 1. Mixed metal nitrates and soluble starchwere converted into'a sol and thenrapidly precipitated at a pH of 8.0 |0.05 as described hereinbefore. After aging -for`24 hours, the pre'- cipitate was separated by filtration and then sub-v jected to quick freezing by dropping small portions intol a large volume of kerosenemaintained atabout 20 external cooling with*`dry ice and acetone. This quickfreezing step-was used toconvert the gelatinous precipitatelinto a moregranular form without loss of structure,

i4 and then treated with 100 ml. of a saturated 'solution of ammonium sulfate for each gram'mole of metal oxides present. This treatment replaced nitrate ions on the catalyst surface by4 sulfate ions without appreciably penetrating the interior of the hydrous oxide micelles. ThisV ad-v dition of sulfate ions to the catalyst surface decreases oxidation of the chromium oxide during drying and also decreases coke formation during use of the final catalyst. After ltration and washing until the wash water showed no sulfate ions when -tested with barium chloride, the precipitate was dried at 100 C. to 110 C. in an aircirculation drying oven. V `The dried material Was heat treated in successive steps of increasing severity at 500 C., 600"l C. and 800 C. A sample was removed for catalyst evaluation after each step of the heatV treatment.

The last two catalysts were preparedfrom dry powders of C. P. commercial chemicals, using the procedure of Example 2, U. S. Patent No. 2,408,140. The catalyst designated is similar in composition to the coprecipitated catalysts except for the addition of potassium.

The'catalyst designated 40 Table II." They show that the most 'active'of these catalysts for ifi-heptane dehydrocyclization :is the coprecipitated preparation heat treatedat 500 C. The catalytic activity is diminished sharply Vfor the higher temperatures of calcination,lalthough measurable dehydrocy'clization 're-` mains after a shortr heattreatment at 800". C.l Neither-'of the'catalysts prepared from dry powlders in accordance with the method of U. S. Patent v-No. 2,408,140 shows perceptible activity for dehydrocyclization.' I 1 Table`II.;Dehydrocycliacttion of -n-heptane; ef-

feet of heat treatmentowiron oz'deechromic j oxide catalysts 1 v '[500" O., atmospheric pressure, 5hr. test periods] Y frozen material wasallowedtotliaw.gradually,

' These examples show that suitably prepared i Y "t oxide are y Vmixtures o'f iron` oxide and chromium 'last traces; of; carbonatos/us., material were reannesse 'active for dehydrcyclization. However, such catalysts are. not as stable to high temperaturesv as would be. desired for commercial application. It. has been found; that this instabilityl and tendencyy to sintercan becounteracted by the incor- 5 poration bycoprecipitation of' a refractory metal oxidesuch as` alumina.

EXAMPLES io EFlEor or- ALnMin-a 12N GorREGLPlTarED- IRON Online CHROMIUM Crimean-mss @Ammers Catalyst preparation- These catalysts were prepared by rapidj coprecipitation` inthe mixing device, `described in Example l. Starch was, omitted fromV the preparations becauset dilution. o the. active metal oxidesy withl relatively large amounts of oxides, such as alumina, which, are noteasily oxidized or reduced decreases, the ease of oxidation of the chromium oxide during the drying stage. Oxidation duringn thecaleination stage was avoided by heating` in as tream of; hydrogen instead of in air.l The method is illustratedbythe following AA stock solution was prepared` containing 0.45 Inol- AltNOss, G-.025-n1ol Cr NOsl3 and 0.0251 ino),y Fe(NO3 3 per liter. (One liter of stock solution corresponded to 0.25, mol mixed oxides corresponding to the mol ratio Alsop. :,oeognezopeo :5 :5.)

' pelleted material Was gradually heatedto 3G-Q10;

in a lY-iydrogenr stream over an 8 hour period. The pellets were; then heated further iny a ear-bon dioxide stream for; 8 hours; While gaduallysincreasing the temperature to 68o.n C., afterwhch, the

moved by passing air over theeatalyst at Soon-Q;

Catalyst evaluation- The dehydrocyclization activities of the once-regenerated catalysts are shown in Table HI'. contained chromiumoxide to-iron `oxidel mol ratios, expressed as the sesquioxides, between 1v1-1552i and 3: 1.

Table VIIL- Deitydrocyclieation of' n-heptcme; -.fe1cct.of alumina in coprecipitated im oxide-lA chromium oxide-alumina catalysts 60' [5 0QC.,.y atmospheric pressure, L.H. S.V.=1, 5-111. testsv once-re.,V

generated catalysts] Initial catalyst. 'Am tolu- Av. con. l' composition, glt er ene in version of 'ovlu'l mol'percent dm enn, liquid: heptane 1 m1 it 65 asg r0d product, to toluene,y patalst g t wt. per wt. perer hl. A1203 cnoareio. fait, cent P 90 5A '8S 14. 5 `13. 5 0. 8 80 10 1U 93 Y 15 14 0. 85 Y Y 70 15 15 93. 5, 25. 5 23. 5 1. 4 70v 20` lf)V 92 24 22. 5 1'. 35 Y' 30 10 92 28. 5 25. 5 1. 5 50 30 20 92. 5 41. 5 36 2.1 3Q 35 35v 92. 5, 45, 5 3,9a .Z l:lo: 2s 42 9i v 34 3o 1.584

From these data, it is concluded that :A

(o) The high hydrogen contents ofi the. gas products indicatel the selectivity of the catalysts for dehydrogenation.

(b) The activity for dehydrocyclization is greater for the lower alumina concentrations but remains higher than that for the chromict oxide gelv described in Exam-ple l up to and including mol-per cent alumina.

Within the range 30V to 'l0V mol per cent alumina, thecatalystsshow improved average activity and stability over parallel catalysts contain.- ing the same ratios of iron oxide and chromium oxide` but in the absence of the alumina. Above 'lo mol perI cent alumina, the stabilityl of the catalysts is excellent but the high dilutions with alumina cause the. activity to; drop oft. There-.- f ore, improvedl catalysts are obtained for alumina, concentrations. between 30 and '2'01 mol per cent.; with the preferred concentrations Within the range 3d to 50 mol per cent, the region of maximum activity and good stability.


Eamon: oF ALEM-ma PnoMoTsRs; 0Nl THE. Acrivirx or COBREOI'PITATED. loN OxmETCHaoMIUM Oxmaf- ALUMINA CaTALys'rs.

This example demonstrates the improved /dehydrocyclization activity ofY iron oxide-chromium oxide-alumina catalysts when small` amounts of alkaline promotersare added.. It should be noted that the optimum amount of the promoters is less for n-heptane delydrocycliyati'on than for naphtha reforming. Since the normal promoter action of impregnated catalysts does not appear fresh catalysts, only datafor regenerated 0,312.- alysts are given. Normal promoter action rels tothe effect on catalytic; activity after dilusion and reorientation ofthe catalyst surface hasfOc-s curr-ed. This, readjustment of` the promoted catalyst;` surface. isnot cheated-by` heat: treatment alone but issubstantiailycomplete after one'cyclo of on-stream and regeneration. Catalyst1 preparation-.ammo basey catalysts were prepared according to themethoc't described in Example 3. The promoted catalysts were obs tainedv4 by adding the calculated amount of the In` all casesy the catalyststratefof the promoter metal to a part of the psdatalyst. The metal nitrates were dissolved in just enough water such that the solution would be; absorbed completely by the catalyst and the solution was addedwith thorough mixing in order to obtain- Vuniformv absorption. After drying for about 18 hours at '75 C. in an air-circulation drying oven, the impregnated catalysts were heated in an air stream over an 8-hour period with the j temperature gradually raised to 600 C. and then maintained at this temperature for 4 hours. This treatment decomposed the nitrates to the correspending oxides.

Catalyst evaluation- The pertinent data are {lf-givenV iny 'Iable 11V; These data show that the additionoff from l: to2 atomic percent of sodium,

potassium, calcium, strontium or ceriuxn improves the catalytic activity. It should be noted that the addition of both copper and potassium is 'more effective than either promoter whenused alone'at the same concentration.

y port.

[500O., atmospheric pressure, L. H. S. V.=1, 5-hr. tests once-regen erated catalysts] Av. con- Initial composiv Av. tolu- Av. gal.- tion of catalyst Promoter, atomic eue in grolf toluene base, mol percent percent based on liquid tane so per cu.

initial mixed product, toluene ft. catoxide base wt. per- Wt per! alyst per A120: Urso: FeaOa cent cent hr' 50 30 20 24 1. 4 50 30 20 27 1. 6 50 30 20 29 1. 7 50 30 20 32 1. 85 50 30 20 23 1. 3 50 30 20 26 1. 55 50 30 20 31 1. 8 50 30 20 27 1. 6 50 30 20 28 1. 65 50 30 20 31 1. 8 50 30 20 0.5 copper 25 25 1.5 50 30 20 3 potassium 0.5 32. 5 30 1. 75

copper. 50 30 20 1 cerium 28 25. 5 1. 5 70 15 15 None 19 17. 5 1. 05 70 15 15 3 otassium 24 23 1.35 30 42 28 one 30. 5 27 1. 6 30 42 28 l potassium 38 33 l. 9v

rials in Contact withthe catalyst support, and

decompose to form only the active metal oxides upon calcination. The rst two requirements are necessary in order to obtain uniform impregnation and to prevent preferential diffusion into vthe met by using an acid solution of metal nitrates or salts of organic acids such as acetic acid. If the impregnation solution is not acid, there is a tendency for a preferential migration of hydrogen 'interior of the catalyst. These requirements are ions into the interior of the catalyst with hydrol- 2 ysis of the iron group metal salt. 'I'his leads to the formation of an iron group metal oxide coating near the outer surfa-ce of the catalyst support, hence a non-uniformly impregnated sup- EXAMPLE 5 ALUMINA-SUPPOBTED IRON 0mm-CHROMIUM Oxma CeTALYsTs Catalyst preparation- The simplest and pre` heated gradually in a stream of air over an 8- hour period to 600 C. to decompose the metal nitrates and chromic a-cid. j Catalyst evaluation-These catalysts show a jchange in activity after the first regeneration,

which it contains.

the change usually bein to higher activity, indieating a freorientation ofthe catalyst surface which is not effected by heat alone. This change is practically complete-after the first regeneration, as shown by substantially constant activity after subsequent regenerations. The data in Table V are for the once-regenerated catalysts.

Tlable V.-Dehydrocycliaation of n-heptane; alumz'na-supported iron oxide-chromium oxide; initial composition,y of active Oxides F6203: Choa-40:60 `(mol ratio +1 atomic percent K [500 C., atmospheric pressure, L. H. S. V.=1, 5-hr. tests once-regenerated catalysta] The results show that all of the alumina-base supports are satisfactory for dehydrocyclization. Calcined bauxite, or Porocel is the least satis'- factory, probably because of the amount oi silica vThe commercial activated alumina and the gel-type alumina known as Uvergel produced catalysts comparable in activity to the coprecipitated catalysts described in Example 4.

An activating support is preferred for these catalysts. An activating support 'is deiined as one which has substantially no catalytic action itself but which has a surfacev structure such' that when impregnated with metal oxides active for `clehydrocyclization forms catalysts whichv are more active than' canV be accounted for solely by compositionv and surface area vof the catalyst. While .the mechanism of such activation is not clearly understood, the distinction between activating and non-activating alumina supports is well known to the art of catalyst preparation;

EXAMPLE s EFFECT oF Assoc/IATED IoNs oN THE CoPR'EcIPI'TATIoN oF IRON Omnia-CHROMIUM OxiDE-ALUMINA 'Cara- -LYsTs- 'V i This example demonstrates the influence vof associated ions, both in regard to promoter action and without promoterl action, on dehydrocyclization activity. 1

Catalyst preparation-Catalyst No. 1 is the datum of comparison for the remaining catalyst. It was the samecatalyst described in Example 4,

prepared by `rapid coprecipitation of the mixed taining 0.25

except thatV it was Ametal nitrates with NHlOI-I.

Catalyst No. 2 was similar to catalyst No. '1, prepared by rapid coprecipitat1on of'mixed metal nitrates with potassium carbonate. A stock solution was prepared' con- `vmol Al(NOs)3, 0.15 mol Cr(NOa')s and 0.10 mol Fe(NO3)3. (One liter of stock solution corresponded to 0.25 mol mixed oxides in the mp1 ratio A1203:Cr203:re2o3=5o:30:20.)V six liters of this solution were added slowly to a vigorously stirred solution of 4.6 mols KzCOs (a slight excess) dissolved in 12 liters of water. t The evolutionuof carbon dioxide'caused the pH of the slurryto drop'to about 6.5 during the precipitaassess aftgrathe ammonio; arie :metal .sans :was complete, thefoH was @raised to fsf oy fthe addi f tionof `Y6 'aing for24:"ilio1i1s, t-he slurry was jltered aiid "the precipitate quickigf roz'en fas described Yiii Eliafmple. imiter allow `ing lto thaw gradually, Vthere was added to 1Jthe Gotlyst evaluation-.lume results aerea-mettiti liable W1. Theya-showftliat ,all ofrthcsmethods of catalyst preparation were satisfactory fand .thatthefcatalysts hauly a dehydmcxcli-zatioo active ity greater than thatiof 'fthefchroinic oxide gel describedinEXample-l.

lPrornoterAconcentration obtained'byincompletelremovalpof potassium carbonate usod'forvprecipitaticn.

2 Promoter aided by 'impregnation ocalcne'dlmetal oxides with metal nitrates rif-promoter metals.

l. Metal .sulfatos consisting ,of ferricsulfate,

*Sllrfy .1.0.0 j ml. '.oi a saturated 1 solution .of amriioiiiurn sulfateper'moleguivalent ofthe precipied 1 metal' oxides ',i. e\., .150' ml. ammonium sulla. .esolutinrorgthe baton. 'The precipitate was :ponateirergsnifate ions jcouidhe deteedrin'the -QWash'Water.. The wettcaks was'thendriem-pel- `l'te'd;arid calcined, 'exactly as described or c atalyl? No. 1. Ihe .ca .ined .catalyst contained A0:3 atouidoer tcer1,t'r'io,tassiilririas'determined'.by'flame l.speci;rophotonietry. :(0.3 atomic per cent K vrep- 'ator'n'ic iper .,celt, f j Abased on .the Aheavy -met'alox'desfas determined by fia'niespectrophotometry.

Catalyst No. 4 was prepared like catalyst No. 1 c'te'pt Lthat'ftliefatio" of aluminum, chromium and ferriclr'iitr'ates was ralteredto fproduce-the indicated mol ratios of metal oxides inthenamount .calculated to produce a1 atomic per cent potassium basedoifl .the metal oxides. ,Flame fsp'ctrophot etay Yi,I niicated va. .slightly higher the potassiumtliromejalum.solution iisedinqthe .catalyst preparation. ".'lhe smallv amountzof'cop- -oersorigmatedtromthehrasslineaor the centri- "fuge basket.

@Watersoluble f aluminum sulfate and. chromium-QOtassiumrsultats.

EXAMPLE 7 These Itests .were v-carried.,out With .thecatalyst .the Veffect :of ..terriperature :and .charge Ton toluene formation. This catalyst was seleg'ted :because .it showed the :marked .ndlltion -`-period which.; characterizes highly;ptorrotedetalsts =9 .ihistinvemion.wrienithey arertestedin the .Ilot-.described ,Themariation inactivity-'with ,time .iomerious ,temperatures when operating atra- .L.H. of .Oisshown graphically--niieurez3- 'he points represent the. tolueriefoontent of fhourlysamples. yfplacing these .values atrthe fmid-pointsof fthe period.over.w11.iclntliey were collected. and'. draw- -iing :ze smooth :curve through them, `a :reasonably .accurate picture of fthe N riation .ofcatalytic .aciivityoterztheeentise;periodisobtained.

Phe .curvesin ,@Fisure :3 .ai d oatea :marked fin- :ducton raeriod, ,the .length of which [decreased with :;rsinetemperature. flu -ea. ;h Case :the 'sex- -tizapoleted Aeuri/.es indicated -.a substantially :Zoro :conversion `at the :beginning fof the .test- At 18.5'f-Q... the fmaximumatalytiactivity was .not reached during' the -liour test period. v'The-tirate required to reaqlrawmagirpum decreased'from about 3.5 hours at 500 C. to 1.5 hours at 525 C. The' -maxirrlumy toluenefcontent ofthe product at 525 C. Was about .Swt. per cent.

The .amarrage values for tlle-llour .test periods are .given in Table FV11.- lFor' Qperatirl 'at .en ZLIH. S of '0;5, the averages `tluerieic'sirltsarlizs f Vfthepro Auctndarerage conversion,Qfneptmejo "ilie-.clwisionei neptaneitotolueae-and.on .the late of toluene formation., .exoresseias gang'pspf tolueneper- .Cu- .ft ,Qfatalyst permur', isgshpwn `vwouldbeexpected, the average conversion of 21 n-heptane to toluene decreased as the charge rate was increased from L. H. S; -'SV.`=0.5 to L. H. S. V.=1.0.A However, the rate of toluene formation in terms of the unit volume oi?` catalyst increased over the range of charge rates tested.

Table VIL-Dehydrocyclization of n-heptane; eiect of temperature and charge rate; initial catalyst composition. FezOszCrzOazAlzOa-ZO;

30:50 (mol ratio) +6.8 atomic percent K mixed metal nitrates and K2C0s [Atmospheric pressure, 5hr. tests, once-regenerated catalysts] Av conver-l Av. toluene Av. gal. tolusion of hep- Temp., L E s v 1n liquld ane to mw ene per cu.ft. C. prod., wt. ene, wt. pep catallyst per percent nt our From the foregoing, it is concluded that:

(a) In order to obtain high concentrations of toluene in the product, severe conditions, of the order of 515 C. or higher and low space velocities such as L. I-I. S. V. of 0.5 Vor less, areto be' preferred;

(b) In order to obtain greatest catalyst eciency with moderate conversions to toluene, milder conditions, such as 500 C. and L. H. S. V. of 1.0, should be used; and

(c) Within reasonable limits, increasing temperatures and decreasing charge rates have the same eiect in increasing the formation of toluene.

EXAMPLE 8 REPLACEMENT oF IRON BY COBALT on NICKEL IN IBoN Oms-CHROMIUM OxmE-ALUMINA GATALYs'rs This example demonstrates the eiect of substitution of atomic equivalents of cobalt or nickel for iron in iron oxide-chromium oxide-alumina catalysts. While most of the experimental work has been concentrated on the iron-containing catalysts because of the inexpensiveness of the from iron compounds, it is evident that the cobaltand nickel-containing catalysts are equal to or` better than those containing iron.

The catalysts are formulated as mixtures of the sesquioxides.v This is merely a matter of `con- Y venience for representing substitution of atomic equivalents of the iron group metals. While the iron-containing catalysts were prepared from ferrie salts, which form the sesquioxide directly,

. the cobalt and nickel catalysts were prepared from salts of the divalent metals which do not form the sesquioxides by simple precipitation methods. Since the valence states corresponding to the active metal oxides ycannot be specified, anV arbitrary formulation is unavoidable.

Catalyst preparation- The iron-containing catalyst in Series A was that described in Examples 6 and '7, obtained by the potassium carbonate precipitation of mixed metal nitrates.Y Y

The iron-containing catalyst in Series B was the' third catalyst in Table III, prepared by coprecipitation of the metal nitrates Ywith ammonium hy-jf droxide. The cobaltand nickel-containingY catalysts were obtained by methods exactly similar to those used for the iron-containing catalysts by substituting cobalt or nickel nitrate for the ferrie nitrate. L Y I z Catalyst evaluation- .-Theresultsare summar- .um foxidevcatalyst was the Table WIL-Dehydrocyclization of n-heptane;

'- replacement ofiron by cobalt or nickel in iron Y oxide-chromium oxide-alumina catalysts (once regenerated catalysts) kIron group metal i Iron Cobalt Nickel Catalysts prepared by potassium carbnate precipitation of mixed metal nitrates containing metal ions in the ratio group metal: chromium: aluminum=20:30:50 l:

L. H; S. V Av. tgluene in liquid prod., wt. pereen Av. conversion of heptane to toluene,

wt. percent Alva. gal. toluene per cu. ft. catalyst per our . catalysts prepared by ammonium hydroxide precipitation of mixed metal nitrates containing metal ions in the ratio iron group metal: chromlum: aluminum=l5rl5z70 l:

Av. ttoluene in liquid prod., wt. per-' cen Av. conversion of heptane to toluene," wt. percent Av. gal. toluene per hour HN QN l Tests at 485 C.,atmos heric ressure 5-hour eriods. vz'rlets at 500 p p' p C., atmospheric pressure, 5-hour periods, L. H: S.

YEXAMPLE 9 REFoRMINe LIGHT PARAFFINIC NAPHTHA WITH COPBECIPITATED METAL OxIDE CATALYs'rs This example illustrates the aromatizationreforming activity of iron oxide-chromium oxide combinations which are active for n-heptane dehydrocyclization. 'Ihe naphtha charge was a hexane-heptane fraction of a Mid-Continent stock containing relatively large proportions of branched-chain paraflins. rIt is representative of a low sulfur, parafllnic stock which is dicult to reform by thermal orcatalytic methods.

Catalyst preparation- The iron oxide-chromi- L Y preparation of this composition described in Example 1, obtained by coprecipitation of the metal nitrates with ammonium hydroxide. The remaining two catalysts Vwere prepared in the manner described for catalyst No. 7 in Example 6, from mixed metal sulfates and ammonium hydroxide. used because of the availability of zirconium and titanium sunates 'as contrasted with. the diniculty of obtaining the metal nitrates.

Catalyst evaluation-The results are summarized in Table IX. The data in Table IX are average values tor. three successive 2-hour test Sulfates were periods, with air-regeneration of the catalysts between each test period. The high octane numbers of the unstabilized liquid products and the high liquid recovery, compared vto thermal reforming, indicate the advantagesof aromatization reforming with these catalysts.

It has been pointed outthat the iron oxidey chromium oxide combinations are active but un- 'l stable l at high temperatures.v

yof naphtha reforming and oxidative regeneration Since conditions are considerably more severe than-those vrequired for n-hepta'nedehydrocyclization, this vexample shows that the' iron oxide-chromium oxide combinations are active even underl conditions of miie entering. 'rue catalysts 'centaining'z'irco-- mxde iandtitanium-.oxide :represent 3,-Example 6. Additionalfpromoters were added Llystsfin `iiliich theopitecpitated frefractorylsupto -ftlffe maloined catalyst by `impregnatioii, Y as r`inpoitjsmon-activating; .-i.fe., mprevestlre estaa dicated in :Table 'X. bility but not the dehydrocyclizaton-factivitysof wtaly'stfevaluaifion-Theresults of thefcatathe active metal oxides. '5 lyst evaluations are shown in Table X.

Table -ilx-Refnmifrg :flight @mamme minimal rwth =cap1=ecipitatdmeta1 Qivite catalyss (538 C. 1000 F.), atmospheric presm'efLfHf'S. VF-flykvfvaluesffm three 2-hr. test periods] Initialmmpostipn of catlyst, mol percent..

Hydrogen content of gas products, 11161.1


Products (based on 100 vsvt. percentlte-i covery):

A s. T. M. iisriiintizmz 1 -B.' i. nous., 10%ai 173,562, ai; 194, 90% at 222,.-E. P.-262 F.

Afl. I. gravity 65.3.

Reid vapor pressure 2.'9"b.

Sulfur 0.012 Wt. percett.

Oetane No., clear:

C. F. R. R. 58.8. C. R. F. M. 57.0.

.REFoRMiNG LIGHT PABMFINIC'NAPHTHXWim-lioiv Sved that the C-tviw f .the Ctaly-Ss' OUDE-CHROMIUM 'OXIDEALUMINA CATALYSTS shown by the research octane number of the iina s iiizedilldue rfbdufeifefese @meer This example -lll-lsates ViIOUS :mhOdS -OI named- Catalyst No.2, prepared froi the metal prePaTm'g @tive rTmn'g-Acatalyts by CQPI'EC' nitrates arid. promoted with a sra'l'l afiiii't tation .of 110n OXldelId h01-111um 0X1f 1e Wlth opotassum,-showedthe highest yield and lowest an actwatmg refractfry oxlde' 1- e? alummg coke-formation for this group of three catalysts- Catalyst :prepqm'uonnse l`am`-157sts. wre GatalystNo--3 Was'a .part of theoatalyst base prepare@ by rapid mecwx'mimn of mme@ met-a1 used to prepare catalyst No. 2 in which the pro*- salts with an alkaline solution as described in m Ot e 1 nntmtbws eased t() 7 atomic Eirepagiyst vp'reputation *from metal guitares Fer PMPOS?? 95'..i n,9fe9?i9n Wi?? 99???? 'and :immori-mm 'hydroxide was ritrarrev in' the UY @@FPQKQWQR appljxlm? Ph? @n2-lysis manner for No.. .7. 4o 0I Catalys't 'N0. A4'.. No.3 S-S- 'The :catalyst preparagons frommetalnitrates otftrgrirznn 1fatzllyst, it `was less cvetan and ammonium hydroxi' ewe'ie made'in-the mar'i- 10 Was impregna e w1 a ner described 1for catalysts-No. 5 and eer Example Small' -mG'u-ht 0f ptassiiim; and it vwas, less active 6, the Apromoters being added by impregnation than eataIyst N014 which had closely the same of theealciieedmetaioxide prepara-tions. 45 amount of potassium.

Test period, hr. Number ci periods,` everegei Properties of unstabilized liquid product:

Micro-Reidvapor press., lb.; '1 'Norwood bromineNtL Micro-octaneNoea-Gl C. F. R.:

C. F. R'. M

Products (basedon'lw lwt.' peti cent, recovery) 5 jy C3-free gasoline, vol. percent..

Dry.'gas,.wt. percent- 14 Coke, Wt.l percent v 1 Oklahoma City napthaseme cbarge'aS-iii TablcIX. i Totem( 8.8`atomlcpercent of'mixe'd`oxides.

, The catalystpreparedirommetalfnitratesiand Im-viewot the foregoing. i-t'nay beeoncliided: potassium carbonate were a, part of catalyst No. (a) catalysts used for aromatizaton reformless when the promoter is added by impregnation 26 The data in Table'XI show thatv both the sup- V `ported and coprecipitated catalysts gave better than when it is incorporated during the copref cipitation, as in the case of catalyst No.' 3.

This second conclusion is strengthened by the results obtained with catalyst No. 5, prepared by impregnating catalyst No. 4 with an additional results with these stocks than those obtained with the light, Mid-Continent naphtha. A com- 'parisonof the octane-yield-coke'gures in Table XI shows that the coprecipitated catalysts gave better results with both naphthas.

2 atomic per cent potassium to obtain a total of 'Y 8.8 atomic per cent potassium in the catalyst.

Catalyst No. was only slightly less active than catalyst No. 4 and much more active than catalyst No.3. u

Without any intent of limiting the scope of the present invention, it is postulated that the effect of the alkaline promoters in aromatization reforming is twofold. The effect of alkali incorporated Within the catalyst particles, as in catalyst No. 4, is predominantly one of improving the structural stability. This benecial effect is obtained for a widerange vof concentrations of the alkali and alkaline earth metals up to about l0 atomic per cent of the alkaline promoter. In addition to this effect, it appears desirable to have la small and more critically limited amount of promoter "on the catalyst surface, such as that obtained by impregnation with 1 or 2 atomic per cent of the promoter metal. This surface alkali improvesthe' adsorptive and 'de'- sorptive behavior of the catalyst surface. There appears to be a limited 'migration ofthe promoter metal ions on the catalyst surface and a limited diiusion from the surface into the interior of the catalyst, as shown by the change in activity, usually an increase in activity, after the rst regeneration. u

v'This influence of small amounts'of alkaline substances on Vthe catalyst surface is illustrated in catalyst No. 4 to`7,incl usive, all of which Vwere prepared from catalyst No. 4 as a base. In catalyst No. 4, the relatively large amounts or alkali were largely lxed within the'catalyst structure. The further addition of 2 per cent potassium, 2 percent copper or 1 per cent barium by impregnation decreased the octane number of the product only slightly but decreased the coke formation sharply. This decrease in coke formation is particularly important where rapid regeneration of the catalysts by air oxidation without excessive heat liberation is required.

EXAMPLEI 11 REFORMING MIDDLEEAsr-NAPHTHAs The preceding examples have been concerned with reformingV a hexane-heptane fraction'of a Mid-Continent paraiiinic n aphtha. This example illustrates the` results obtained with lessvrefrac-f1 tory stocks. V

The Uvergel supported catalysts were the 400 F. boiling range fraction Vof a'Middle East crude. The results are summarizediin-irrable *Table YXIe- Reformingr Middle East naphthas. potassium-iron amide-chromium oxide-alumina catalysts `[15.38 C. (l000 F.).uatniosphericpressura L. H. S. V.'=1]

Catalyst I1npregnated, C

0.75 moles opreeipitated, (rezoconoa IlrealiHtEeS-nf =40'60+1%K) cro -i -3` per 100 g. Uverzoof'o 22 a K gel alumina f- Naphtha charge Light 1 Heavy i Light 1 Heavy C. F. R. R. `clear octane No. Y of charge 56 42. E 56 42. 5 Properties of unstabilized liquid Product: Norwood bromide No 22. 4 20. 3 21. 3 23. 1 v Micro-octane NOTO. F.

R.-(.llear.' V 83.5 87 85 86 Products (based on 100 wt.v

percent recovery):

Ca-free gasoline, vol. perf' cent 81.8 76. 8 81. 7 81. 7 Dry gas, Wt. percent.. 7. 4 11.0 7. 4 7. 4 Coke, wt. percent 7. 7 9.0 6. 7 7.8

Y l Light naphtha, mixed Iranian. A. Si. T. M. distillation: I. B. P. 121 F., y10% 8.111619, 50% 8.151212, 90% at 267, F. B. P. 311 F. z Heavy naphtha, Gach Saran. A. S. T M. distillation: I. B. P.

5, F. B. P. 395 F.

248 F., 10% at 276, 50% at 312; 90% al; 36

i Y EXAMPLE 12 REFOEMING PAEAFFINIC LIGHT NAPHTHA WITH ALUMINA-SUPPORTED CATALYsTs Catalyst preparatiom'The three catalysts were prepared-by the same procedure. One literportions of the catalyst supports (Uvergel.or Porocel alumina) were impregnated with 0:15 mol potassium carbonate dissolved in enough water to moisten the support. The amount of potassium carbonate Was selected to produce 0.03

. gram atom ofpotassium per 100 cc. support. The

575::Limpregn'ated support was dried for about 18 hours at C. in an air-circulation drying oven, then l heated gradually in a muiie furnace over a 6-hour "'iinal temperature for 4 hours. After cooling, the

'60'"potassium-impregnated supports were impreg- 'period to '600 C. and then maintained at this Y-natedvvith solutions of mixed metal nitrates cal- Y. culatellto produce 0.1 mol ofgmixed metaloxides percc. of support. The'reimpregnated mar terials were then dried and recalcined as described for the potassiumv impregnation. The products then containedjOJ mol of catalytically active metalY Loxidesf promoted with 3 atomic per cent K pe1`jq7`100fcc-1of support' l(orl 30 atomic per cent K base d 0n theactive metal oxides).

Catalyst e1jaZ aatipn. The results obtained with these catalysts,"su'mmarized in TableXIIy'show lysts had exceptionally lgood activity 'for aro# mati'aationreformin'gof light parainic napl'itha.

` Table XUL-Reforming paranc light naphtha with allumina-supported catalysts Test conditions:

Temperature, F 95() L. H.. S. Y 6.5.,v

Number of testpcnnd av i i Properties of unstabilized liquid product:

Norwood bromine No 26.2

Mcrooctane No., C. F. R. R.Clear 80 Products (based on 100 wt. percentrecovery):

Cr-free gasoline', vol. percent 86.9

Dry gas, wt. percentA 5.5-..

Coke, wt. percent 5.8

l Oklahoma City naphtha; saine charge as in Table IX.

EXAMPLE 13 This example illustrates the use of catalysts of this invention under conditions of steam dilution. The steam dilution decreases the average coke formation and thereby prolongs the onstream period between regenerations. vIn order to counteract the adverse eieot of watervapor on the dehydrocyclzation of paralflns lef. Mattox, J. Am. Chem. Soc.`66, 21Q59 (194ml, the operating temperatures must beincreased- Catalyst preparation-Catalyst No. l was identical with catalyst No. 5, Example catalyst No.v 2 wasV identical with Vcatalyst No. 5, Example 6; catalyst No '.3 was identical` with catalyst No. l, Example 12; catalyst No. 4 was identical with catalyst No. 2, Example 12.

Catalyst evaluation-Ehe average results for duplicate l-h-our test periods are shown in Table XIII. -The yields of C-affree gasoline were superior to those. obtained in the absence of Water. This increase in yield for substantially the same octane number .was partly a result of the lower coke formation and also because of the higher olen formation in .the presence of all Vinert diluent such as steam.

REronMme DEPENTAMED LIGHT NAPHTHA ltrrn Hermosas Dix-turion This example illustrates the. superiority of the sureyvas l5@V p. s. i. g., ,and the hydrogento hydrocarbon mol ratios Werfe: i. The results are summarized in Table XIV. It is evident from the data Table XIV that the iron-containing catalyst gave a better liquidi recovery than the hydrofor'ming ncatalyst for vthe same octane number. This improved liquid recovery resulted partly Tabla XIILa-:Revforming paramnic light v. 'rtaphtha with steam dilution [593 C. (llllO FJ, atmospheric pressure,

'H'. Si V.=1; mol percent steam in charge; lll-hour test periods, Av. of 2 test-sl i K *n i 'roducts based on lg'wt. percent Properties oi unstabxlized products` A 7*' mummy.

" Gatalyt M. (Ja-n10@ z` f v ,oR' g gasoline, Coke, wtt.

No. No. press. ,pm ,pement i persen FezOa:CrzOazAl20a=20z3Q:50 (Mol Baltico- F8395 K o mixed metal nitrates coprecipitated by NHrOH; f impregnated with KOAc 25. (i` 0 81 l1 fr 1 1 FezOsgGrrOi:Alzs28ni2g3ll Mpl Ratio)+1% K; p.

mixed metal nitrates copreorpitatedby NHAOH; Y f impregnated with KNOa 32. 5 73. 5 4. 5 90 7. 2 l l. 4 0.1 M01 (FezO32Cr203=,4026Q) 0n G v on ce. Uvergel alumina I 34. 0 78. 5 3. 3 T8. 5 11.15 2.1.0

0.1 Mol (GoiOnCrgOFszO o n gram atomsK on Y v k lODcc. Uvergel alumina.- 32.6 78:.5, 3.2 88.5 1 9. 15 .l L5

. i'oklaliomaity naplithmsubstantlally the sameaschargein Table C. Y

Table XIV.-Reforming paramnic light naphtha 1 with hydrogen dilution [Av. values for three 5hr. test periods] Catalyst Harshaw F9203: CrzOaIAlzOa gli?? 2o:ao:5o mol ra- MOO g tio -j- -6.8 K, co- Uvm precipitated from el. metal nitrates by almina Kao o Test conditions:

, Temperature, f C `490 l 638 Pressure, p. s. i. g 150 150 L. H. S. V 0. 66 0. 55 Dilution, mols Hz/mol charge.. 5 5 Properties of unstabilized liquid product:

-Reid vapor pressure, lb 5.6 7.77 Norwood bromine No 0. 6 18. 7 Micro-octane N o Clear R. 8l. 5 82 C. F. R. 76 75 Products-based on 100 wt. percent recovery:

Ci-free gasoline, vol. percent 81.5 88 Dry gas, wt. percent 15. 5 8. 1 Coke, wt. percent 0. 6 1. 4

l Oklahoma City naphtha; same charge as in Table IX.

EXAMPLE DSULFUBIZATION oF PARAFFINIC LIGHT NAPHTHA v'I'.hisexample illustrates the desulfurization of naphtha containing high concentrations of refractory sulfur compounds. It is well known that organic sulfur compounds such as mercaptans and disuldes are easily removed or decomposed by catalysts of low activity such as clay and bauxite. However, the refractory sulfur compounds such as thiophene are not all'ected by such treatments. Therefore, desulfurization of a naphtha containingrrelatively, high concentrations of thiophenic sulfur illustrates the effectiveness of the catalysts of this invention for removal'of the more difficultly removable sulfur compounds.

The iron-containing'catalyst was identical with that used in Example 14. The cobalt-containing catalyst was identical with the cobalt-containing catalyst in Table VVIII-A. y

Catalyst evaluation-The'"catalyst evaluation conditions were substantially the same as those used for aromatization reforming in the presence of hydrogen. The liquid products were causticwashed in order to remove dissolved hydrogen sulde before obtaining octane numbers. The results are summarized in Table XV. i

-ratte XVLDe`suzfuri`zation 'of dramma iight naphtha 1 f Catalyst FezOsCzOs: A1203 :30: CorOCrrOs.. 1 6 8 K. A1203 20.30.

50 mixed metal mixed metal nitrates ca nitrates co-Y precipitated preclKpi-lfd by Kroos ,by l s Test conditions:

Temperature,4 .'F- l, .000. 950 Temperature, p. s. 1. g .4 Y 150 '150 Dilution, mols Ha/mol charge. 5 5 Test period, hr. 5 5 Properties of unstabllized liquid product:

Reid vapor pressure, lb. 5. 3 4. 4 Norwood bromine No. 2l. 7 15. 3 Total sulfur, wt. percent 0. 035 0. 025 Micro-octane No., C. F. R. R

Clear 69. 5 66. 5

Table XV.-Desulfurizati0n of paramnic Alight naphtha 1.-*Continued.

Catalyst FezOztCrzOa:

. 50 mixed metal mixed metal nitrates coggag precipitated Products, based on 100 wt. percent' I recovery:

Cri-tree gasoline, vol. percent... 94. 5 93. 3 Dry gas, Vwt. percent 5. 5 3.10 Coke, Wt. percent O. 8 i l. 5

1 Charge: Oklahoma City naphthmsame charge as inTable IX except for the additionof thiophene to obtain a total sulfur content of 1.04 wt. percent,.substantially all oi which was thiophenic sulfur These data show that the sulfur removal was greater than 90 per cent for both catalysts. The. sulfur in the charge decreasedV the extent of aro.,- matization in the same manner that is known to occur for other aromatization catalysts Whenused under similar conditions, such as molybdenaalumina. However, the liquid recovery was high and the coke formation low in both cases. A

Although the present invention has been described in conjunction with certain embodiments, it is to be understood that modications and Variations therein may be madewithout departing from the spirit and scope of theinvention, as those skilled in the art will readily understand. Such variations and modications are considered to be within the purview and 'scope of the appended claims.

What is claimed is: l.

1. A process for effecting aromatization reforming of hydrocarbon mixtures containing aromatizable hydrocarbons, which comprises ycontacting said hydrocarbon mixtures with a chromium oxide-iron group metal oxide catalyst composition obtained by initially intimately mixVv ing moist,undred hydrous chromium oxide withmoist, undried hydrous iron, group metalfoxides in proportions such that the final chromium' oxide-iron groupmetal oxide catalyst .composition will contain chromium oxide and iron group metal oxide in a Vmol per cent ratio, expressed onA -thellbasis of the metal sesquioxides, varying between about 40:60 and about 70:30,- respectively,

but below aboutv 350 C. to produce a dehydrated mixture; comminuting said idehydrated'mixtiire; f

. about '000 C., under non-oxidizing. conditions and lfora periodof time of at least-'about fve hours; at'temperatures'falling within the'ran'ge varying between about 450 C.vv and about 650 C.; at hydrocarbon partiahpressures Ifallingyvithin the range varying from `atmospheric and up to about. 30 pounds per square inch gauge;Y 'at liquid hourly space velocities falling within jthe range varying vbetween about 0.2 and` aboutf2.5'; and

underp total pressures varying from atmospheric and vup to about 300 pounds' persquare inch gaugr- 2. A process for eiecting aromatization re-V forming of hydrocarbon mixtures containing aromatizable hydrocarbons. whichr comprisescontacting said hydrocarbon mixtures with a catalyst comprising a chromium oxide-iron group metal oxide composition obtained to produce a mixture; treating said mixture'at temperatures suilicient to dry the mixture by initially' v accesses intimately mixing moist, undried hydrous chromium oxide with-moist, undriedt hydrous iron group metal oxides in proportions such that the final chromium oxide-iron group metal oxide' composition will contain chromium oxide and iron group metal' oxide in a mol per cent ratio, expressedon the basis of the metal sesquioxides, varying between about 40:60 and about '70:30, respectively, toproduce a mixture; treating said mixture at temperatures sufcient to dry the mixture but below about 350 C. to produce a dehydrated mixture; comminuting said dehydrated mixture; and calcining said dehydrated mixture at temperatures varying between, about 500 C. and about 600 C., under. non-oxidizing conditions and for a period of time of at least about five. hours; alumina in amounts varying between. about 30:Y mol per cent. and about 95 molperv cent, lbased on the' totalV oxides in the catalyst; and a-promoter selected Yfrom. the group consisting: of potassiumoxide andiA copper oxide; inv amounts of atleast about 0.2' per cent and up to about- 52 per cent, by Weight; at temperatures falling within therangevaryingl between about 4859'. and about 550n C.; at hydrocarbon partiai pressures falling within the range varying from atmospheric and up to about 30- pounds per square inch gauge; at liquid hourly space' velocities falling: within the lrange varying between about 0.5 andL about 1.0; andl under total pressures varying from atmospheric and up to about 30'poundspersquare inch.

3. A process for eiecti'ng desulfurization and aromatization reforming offsulfur-bearing hydro'carb-on mixturesy containing aromatizable hydrocarbons, which comprises contactingA said hydrocarbon mixtures with a catalyst comprising a chromium oxide-irongroup metal oxide composition' obtained byl initially intimately mixing moist, undried hydrous chromium oxide with moist, undried hydrous iron group metal oxides in proportions such that the nal `chromium oxide-iron group metal oxide'fcomposition will contain chromium oxide'and iron group metal oxide in a molper cent ratio, expressed `on the basis of the metal sesquioxides, varying between about 40:60 and about r{0:30, respectively, to pro'- duce` a mixture; treating said mixture at *temperatures sufficient to dry the mixture but below about 350913.V tol produce a dehydrated mixture;l

comminuti'ng" said dehydrated mixture; and calcining saiddehydratedmxture at temperatures varyingv between about500 C. and about 60.0' C., under non-oxidizing conditions and for a period of timev of at leastV aboutv five hours;r alumina in amounts Varying betweenl'about 30 mol; per cent and about 95`-mol percent, based onrthe total oxides in the'vcatalyst; and a promoter selected; from the'group consisting-of potassium oxide and copper oxide, :in amounts'of atleast about 0.2 per cent-and up to about 5 per cent, by weights; at temperatures falling within the .range varying .between-.about 485 C. z and about 550 C.; at hydrocarbonepartial pressures. falling within the range varying Vfrom. atmos# pheric and up to about 30 poundsper square inch gauge; at liquid hourly space velocities falling within the range varying between about 0.2 and about 0.5; in the presence of hydrogen in mol ratios of hydrogen to hydrocarbon varying be tween about 1:1 and about 5:1, respectively; and, under total pressures wrying between about 50 and about 150 Apounds per square i-nch gauge.

4. A process for effecting aromatization reforming .of hydrocarbon mixtures Containing aromatizable hydrocarbons, which comprises contacting said hydrocarbon mixtures with a catalyst comprising a chromium oxide-iron group metal oxide composition obtained by initially intimately mixing moist, undried hydrous chromium oxide with moist, undried hydrous iron, group metal oxides in proportions such that the nal chromium oxide-iron group metal oxide composition will contain chromium oxide and iron group metal oxide in a mol per cen-t ratio, expressed on the basis of the metal sesquioxides, varying between about 401:60 and about :30, respectively, toprodnce a mixture; treating said mixture at temperatures sucient to dry the mixture but below about 35.0 C. to produce a dehydrated mixture; comminuting said dehydrated mixture; and cai'cining Said dehydrated mixture at temperatures varying between about 500" C. and about 600? C., under non-oxidizing conditions and for a period of time of at least about ve hours; alumina in amounts varying between about 30 mol pery cent and about mol per cent, based on the total oxides in the catalyst; and a promoter selected from the group consisting of potassium oxide and copper oxide, in amounts of at least about 0.2 per cent and up to about 5 per cent by weight; at temperatures falling within the, range varying between about 500 C. and about 690 C.; at, hydrocarbon partial pressures falling Within the range varying from, atmospheric. andup to, about 3,0 poundsv per square inch gauge.; at liquid hourly vspace velocities falling within the range. varying between about 0.5. and about 1.0.;l in the presence of steamV in mol ratios of steam to hydrocarbon varying between about 1:2 and about 1 4, respectively and under total pressures vary` ing from atmospheric and up to about 30 poundsA r per square inch gauge.

wrrLmi/r er LANG. WILLIAM A STOVER., CARLOS L.. Gu'raarr.v

References Cited in the. le of this patent vUNI'IED STATESy PATENTS Number Name Date 1,486,781 Meigs' Mar. 1-1, 1924 2,184,235 Grail et al( Dec. 19, 1939 2,203,826 Komarewsky Juney 11, 1940 2,239,000 .Groombridge Apr. 22, 1941 2,337,191 Greensfelder' et al. Dec. 21, 1943 2,399,895 Segfried et al. May "I, 1946 2,401,246 `Hull j May 2B, 1946 2,401,846 Sumerford June 11, 1946 2,408,131 Voorhies Sept. 24, 1946 2,408,140 Gutzet Sept. 24, 1946 2,474,212` Black June 28, 1949 2,486,361?V VNahiri et al. Oct. 25, 1949 2,487,564 i `I ayng Nov. 8, 1949 OTHER REFERENCES Chemical Abstracts, vol. `37co1.;12.064 (1943)..

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U.S. Classification208/134, 208/136, 585/407, 208/243, 502/314
International ClassificationB01J23/86, C07C5/41
Cooperative ClassificationB01J37/08, B01J23/862, B01J23/866, B01J23/86, C07C5/412
European ClassificationB01J23/86D, B01J23/86B, B01J37/08, C07C5/41B, B01J23/86