US 2645605 A
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Patented July 14, 1953 UNITED STATES PATENT. OFFlCE 2,645,605 REFORMING AND oATALysTs THEREFOR William H. Lang, Wenonah, and Carlos L. Gutzeit, f Woodbury, N. J assignors to Socony-Vacuum Oil Company, Incorp New York orated, a corporation of No Drawing. Application April 27, 1951,
v 40mm. (01. 196-50) This invention relates to new reforming catalysts characterized by the combination, in a single catalyst composition, of the catalytic properties of isomerization and of "aromatization, and to a process for effecting naphtha reforming utilizing these catalysts. More particularly, the present invention is concerned with new reforming catalysts containing chromia, fluorine and an amphoteric metal.
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 than those of aliphatic and naphthenic or alicyclic hydrocarbons, saturated and unsaturated, although the octane number ratings of certain aliphatic hydrocarbons are as high or even higher. Ingen- :era1, therefore, the conversion of saturated hydrocarbons into unsaturated hydrocarbons through dehydrogenation, and the conversion of aromatizable aliphatic and alicyclic hydrocarbons into aromatic hydrocarbons through dehydrogenation or cyclization or both, i. e., dehydrocyclization, depending upon the type of aromatizable hydrocarbon, are expedients whereby the low-octane hydrocarbons are converted into the corresponding higher octane hydrocarbons. several processes, involving these reactions, have been proposed for the purpose of producing gasolines having improved antiknock properties from petroleum naphthas. These operations are :gen-
erically referred to as reforming and the conditions of temperature, pressure (including hydrogen pressure), and residence time are referred to as reforming conditions.
Most of the proposed reforming processes involvethe use of catalysts. type of reaction or reactions which they primarily promote, the reforming catalysts have been termed aromatization catalysts, dehydrogenation catalysts, dehydrocyclization catalysts, etc. Indeed, these catalysts also promote cracking,
thereby producing normally gaseous hydrocarhens and carbonaceous deposits on the catalysts.
Controlled or selective cracking'is advantageous from two standpoints. In the first place, it increases the yields of desired product, through the conversion of the higher-boiling constituents of the charge stocks into fractions boiling within the gasoline boiling range (-80 F. :to 400 F.) :and by decreasing the conversion of fractions boiling within the gasoline boiling range into norm-ally The reactions involved are well known and Depending upon the gaseoushydrocarbons. In the second place, it further increases the octane number rating of the reformed gasoline through the formation of un- 'cyclization catalyst. It does not promote isomerization to anygreat extent and is not selective in its cracking activity. Thus, in a typical reforming operation in 1 which a chromia-onalumina reforming catalyst is employed, a satue rated gasoline, such as, for example, a straightrun gasoline, which comprises a mixture of paraffinic and alicyclic hydrocarbons, is subjected to reforming conditions, whereby, the aromatizable alicyclic hydrocarbons are dehydrogenated into aromatic hydrocarbons and the aromatizable parafiinic hydrocarbons are dehydrocyclized into aromatic hydrocarbons. -.The improved octane number rating of the reformed gasoline obtained fromsuchan operation may be attributed, therefore, primarily,-to the formation of the aromatic hydrocarbons.
It is'well known that chromia-on-alumina catalysts are among themost active of the dehydrocyclization catalysts This high activity is obtained at low pressures, such as atmospheric, and at temperatures of the order of 900-1000" F.
It is also well known that when dehydrocyclization catalysts,such as chromia-alumina, are employed under hydrogen pressure, the dehydrocycliza'tion activity is preferentially decreased,
compared to the dehydrogenation of naphthenes containing six-membered rings. In spite of this, it has become common practice to use such catalysts under hydrogen pressure in order to gain the advantage of reduced coke deposition. Such oprerationsare predicated upon; striking a balance between'the practical advantages of reduced coke formation and the decreased aromatization, especially the reduced dehydrocyclization, obtained under hydrogen pressure.
As stated hereinbefore, the octane number ratings of certain aliphatic hydrocarbons are as thereby permitting continuous operation for long periods without interruption for oxidative regen- In copending application for patent Serial No.
216,460, filed on March 19,1951, by Rowland C. Hansford, there is disclosed and claimed a catalyst containing chromia, specified amounts'of fluorine, and alumina. In accordance with copending application Serial No. 218,291, filed on March 29, 1951, by Carlos L. Gutzeit, these chromia fluorine alumina catalysts promote aromatization and isomerization reactions in reforming operations involving hydrogen pressure.
From a theoretical standpoint, the chromiafluorine-alumina catalysts are capable of producing gasoline in the highest yield for a given octane number rating. This follows from the fact that these catalysts effect the conversion of cyclohexanes and of alkyl cyclopentanes into aromatic hydrocarbons with a smaller increase in density than is the case in the dehydrocyclization of aromatizable paraffinic hydrocarbons and, also, effect the isomerization of paraffinic hydrocarbons with concomitant increase in octane numberratingand with substantially no volume change.
In the copending applications referred to, it was found that, in accordance with the teachings of the prior art, in aroma-tization reforming at atmospheric pressure, the fluorine-containing chromia-alumina catalysts were inferior to the fluorine-free chromia-alumina catalysts. Also, in accordance with the prior art, it was found that, in reforming operations involving the use of fluorine-free chromia-alumina catalysts, hy-
drogen pressure showed a tendency to suppress 'aromatization activity, so that it was necessary to increase temperature and/or apparent contact time in order to maintain the conversion by such catalysts at a reasonable level.
mation could be achieved at pressures of up to 200 pounds per square inch gauge and a hydrogen-to-naphtha mole ratio varying between about 2:1 and about :1, respectively, with only minor disadvantages in the octane number rating-gasoline yield relationship. However, at pressures of 500 pounds per square inch gauge and higher, using hydrogen dilutions falling within the same range of variation and under.
naphtha mole ratio of 4:1, caused slight inferior-,
ity at atmospheric pressure, slight superiority at 200 pounds per square inch gauge, and marked superiority at 500 pounds per square inch gauge. At pressure of 500 pounds per square inch gauge and higher, the coke deposition was negligible,-
Such compensa tory octane number level with reduced coke foractivity of the chromia-alumina catalysts.
eration to remove carbonaceous material.
In the copending applications, it was stated that the improvement in activity of the fluorinecontaining chromia-alumina catalysts under hydrogen pressure -was due to a superposition of isomerization activity on the dehydrogenation Under optimum conditions for dehydrocyclization, such as at atmosphericpressure, this isomerizing action caused only a small part of the octane number rating increase but caused a marked increase in coke formation, resulting in an overand the balance, an active alumina base.
all deleterious effect. Under increased hydrogen pressure, where dehydrocyclizaticn was diminished and coke formation became small or negligible, the isomerization contributed a very considerable part of the over-all octane number rating increase, and the over-all activity of the catalyst for aromatization reforming was increased.
Isomerization-aromatization catalysts may be considered to be bifunctional catalysts, one function being that of cracking-isome'rization and the other that of dehydrogenation, although these functions need not be entirely separate and distinct. The chromia-fluorine-alumina catalysts belong to the class wherein such functions are distinct and can be separately controlled by a judicious selection of the active components. The fluorine or acid component functions as the cracking-isomerization' promoter while the chromia component functions as the dehydrogenation promoter. While the alumina component is not strictly non-catalytic, it may, as a first approximation be considered to be merely an activating support which acts as a high surface-area carrier for the catalytically active ma" terial and to prevent crystallization, migration or volatilization of active components. Therefore, the ratio of-fiuorine to chromia was selected so that the fluorine component would produce isomerization but only negligible cracking, while the chromia component promoted the dehydrogenation of the aromatizable alicyclic hydrocarbons at the relatively high space velocities necessary to eifect selective isomerization with the fluorine component.
Accordingly, the reforming catalysts of the co- :pending application filed by Hansford comprise combinations of from. about 5 per cent by weight 'to about '70 per cent by weight of chromia, calculated as CI203, with from about 0.1 per cent by weight to about 2.0 per cent by weight of fluorine, More particularly preferred, however, are stated to be combinations of from about 10 per cent by weight to about 35 per cent by weight of chromia, calculated as CrzOs, with from about 0.2 per cent by weight to about 1.5 per cent by weight of fluorine, and the balance, an active alumina base.
The chromia-fluorine-alumina catalysts of this copending application were found to be unstable under oxidizing conditions, either during catalyst preparation or during oxidative regeneration. Indeed, the specification of the copending appli cation states that it is essential to effect the calcination in a hydrogen atmosphere. For this reason, as set forth in the copending application filed by Gutzeit, the indicated and preferred use of these chromia-fluorine alumina catalysts is in reforming operations involving relatively high hydrogen pressures, of the order, of 500 pounds per square. gauge and higher. As stated hereinbefore, at these pressures,'the coke deposi tion is so low as to preclude the necessity of oxidative regeneration of the catalyst, therebypermitting continuous operation for long periods of time. Eventually, of course, the cokedeposit will reach such a magnitude as to seriously impair the activity of the catalyst. In normal, commercial operations, and using catalysts that are stable under oxidative conditions of regeneration, the catalysts would be regenerated and reused. If'the chromia-fluorine-alumina catalyst is so treated, the fluorine-content of the catalyst is lost rapidly and with it, the advantages of the catalyst. Accordingly, expedients whereby these chromia-fiuorine-alumina catalysts are stabilized are manifestly of considerable commercial significance.
It has now been discovered that it is possible to stabilize these chromia-fluorine-alumina :reforming catalysts. It has been found that the addition of certain amphoteric metals, viz., antimony, tin and bismuth, in specified amounts, effects the stabilization of the fluorine in chromiafiuorine-alumina reforming catalysts.
The addition of amphoteric metals to chromiaalumina dehydrccyclization catalysts is well known. Thus, for example, antimony has been added to chromia-alumina catalysts as a promoter. The function of the amphoteric metals herein is not that of a promoter, but that of a stabilizer for fluorine.
Accordingly, it is an object of this invention to provide improved reforming catalysts. -Another object is to provide efiicient aromatization-isomerization catalysts. Still another object is to provide improved chromia-alumina reforming catalysts. A further object is to afford an improved reforming process. An important object is to provide a catalytic reforming process to achieve improved octane number rating-gasoline yield relationships. A more specific object is to provide a catalytic reforming process utilizing a catalyst containing chromia, specified amounts of fluorine, specified amounts of an amphoteric metal, and alumina, and hydrogen pressures. Other objects and advantages of the present 'invention will become apparent to those skilled in the art from the following description.
Broadly stated, the present invention provides:
1'. A. reforming catalyst comprising a combination of specified amounts of chromia with specified. amounts 'of fluorine and specified amounts of an amphoteric metal selected from the group consisting of antimony, tin and bismuth, supported on an active alumina base; and
2. A. process for effecting reforming of petro leum naphthas, which comprises contacting a petroleum naphtha with the aforesaid reforming catalyst, under reforming conditions including hydrogen partial pressures.
In accordance with the present invention, the amount of antimony, tin or bismuth to be incorporated in the catalyst must be equal to from about 0.5 to about 2 times, preferably, from about 0.5 to about 0.75 times, the amount calculated to form the normal fluoride of the amphoteric metal in its lower valence, i. e., SbFx, SnFz and BiF' a, on the basis of the available fluorine present in the chromia-fluorine-alumina catalyst.
There appears to be nothing critical in the method of preparing the catalysts of the present invention. In general, any method of catalyst preparation known to the prior art can be utilized. For example, the catalysts may be prepared by adding chromic acid and hydrogen fluoride, in
predetermined amounts, to an alumina base, followed by washing, drying, comminution and calcinatio'ri under conditions adapted to yield produc'ts which have relatively high surface areas. Or,.alumina pellets may be impregnated, initially, with an aqueous solution of ammonium fluoride followed by washing, drying and calcining, and, subsequently, with an aqueous solution of chromic acid also followed by washing, drying and calcining, the'amounts of fluorine and of chromia in the final catalyst being controlled by using calculated amounts of ammonium fluoride and of chromic acid, based on the weight of alumina and just enough water, in each case, to be completely absorbed by the pellets. The order of impregnation may be reversed or can be combined in one impregnation step. Or, commercially available or previously prepared chromia-alumina catalysts,- in bead or pellet form, such as those described in application for Patent Serial Number 201,537, filed by Stover and Wilson on December 14, 1950, may be impregnated with an aqueous solution of ammonium fluoride, the amounts of fluorine in the final catalyst being controlled by using calculated amounts of ammonium fluoride and just enough water to be substantially completely absorbed by the beads or pellets.
Antimony, tin or bismuth can be introduced into the initial chromia-alumina gel by incorporating the sodium salts of the acidic oxides, such as sodium antimonate, sodium stannate and sodium bismuthate, into the sodium aluminate solution. Or, since the sulfides of antimony and tin are alkali soluble, the finished chromia-fluorinealumina catalysts can be impregnated with an ammonium sulfide solution of the metal sulfides.
Whatever the method of preparation employed, the catalyst is dried and then calcined. By way of non-limiting examples, the drying may be effected at temperatures of from about 300 F. to about 900 R, and the calcination, at temperatures varying between about 900 F. and about 1200" for a period of time of about one hour to about 10 hours.
It will be apparent to those skilled in the art that numerous compounds, can be used as sources for the various components of the catalysts contemplated herein. Thus, for example, fluorine may be introduced as dry hydrogen fluoride, aqueous hydrofluoric acid or an aqueous solution of ammonium "fluoride (NI-14F or NH4F-HF). Aqueous solutions of chromic acid, ammonium bichromate or chromium acetate may be used as sources of chromia.
Any of the commercially available aluminas of high surface area, such as gel-type alumina or activated alumina, consisting principally of gamma-alumina, may be used to prepare impregnated catalysts of the type contemplated herein. Or, precipitated. alumina may be prepared in accordance with any known procedure suitable for the production of high-surface area alumina utilizable as a catalyst support. Thus, for example, aluminum hydroxide may be initially precipitated using aqueous solutions of aluminum nitrate, aluminum sulfate or aluminum chloride and the hydroxides or carbonates of ammonium,
sodium or potassium. Residual sodium or potas- V sium ions may be reduced to negligible amounts by base-exchange with ammonium salts. Traces Z cili'tatesz-the' washing out of? anions. Freezingan'd thawing? the gelatinous, hydrous alumina converts'it to a more easily filterable or centrifugable. material and lowers its water-content, therebyfacilitating:washing; The addition of ammonium hydroxide orof neutral salts, such as ammonium nitrate, to the 'wash water facilitates the removal of: other ions and prevents peptization of the alumina toward the. end of the washing. operation.-
The method of addition of either the amphoteric metal or the fluorine is not critical but islimited' by the. solubilities of the compounds involved; The preparations given in the-examples set. forth hereinafter were selected to provide uniformityinthe method of. preparation rather than simplicity or economy. It will be. apparent: to those skilled in the art that various possible methods include:
((1.) Addition to. gel-forming solutions;-Any such additions should be madeto the sodium aluminate rather than to the chromium acetate. The normal halides cannot be added because aluminum fluoride will precipitate if a soluble fluoride is added. Actually, antimony'fluoride; SbFs, is soluble while stannous fluoride; SnFz; and bismuth fluoride; BiFs, are not. However, the alkali salts of antimony and tin, such as sodium antimonate and sodium stannate, can beradded to the sodium aluminate. The analogous b-is-' muth salt, viz., sodium'bismuthate, iswater-soluble-but is-a' powerful oxidizing agent, hence, although'it can be'used, it is not particularly desirable.
(b) ImpTegnation.-Wet impregnation is generally preferred because'of betteruniformity of impregnation; but it is not essential. The beads, for example, can be impregnated with antimony fluoride, SbFs, but this will limit the atomic ratio of Sb2F to 1:3 (or 1.0 times the ratio of the normal, lower-valence fluoride).
Impregnation of either wet or dry beads with antimony or tin is best carried out with ammonium sulfide solutions of the antimony sulflde (SbSs) or tin sulfide (SnS) because the-solutionsdo not damage the bead structure ordo not introduce undesirable impurities. Sodium sulfideorpotassium sulfidesolutions can be used but this'will necessitate following the impregnation with acidification to precipitate the sulfide, followed by washing and base-exchanging to remove the alkali metal ions. Bismuth sulfide (BiSs) cannot be introduced in this manner because. it is not soluble in alkali sulfides.
The other common salts of antimony, tin-and bismuth, such as the nitrates and chlorides, hydrolyze' easily and are soluble only in strongly acid solutions. Such solutions cannot be added to the wet beads because the acid will partially dissolve the alumina or the chromia or both. However, such solutions can be-and. have been used to impregnate dry beads.
The fluoride ion can be added separately'or at the same time as the aqueous solution of the amphoteric. metal, since it willnot form a precipitate with the alkaline sulfide solutions of antimony ortin sulfides and will not precipitate in the strongly acid sclutionsof any of these metals (Sb, Sn, Bi).
Fluorine is strongly adsorbed. by (or reacted with) the surface and hence, is not easily washed out. Therefore, it can be added either beforeor after the addition of the amphoteric metal.-
The catalysts can be used many of the eon.-
ventional forms such as=powder; pills, spheres,-
8? extrudatesor irregular fragments, all of' a size suitable for thereaction system to beemployed.
.qAny mixture of hydrocarbons suitable as a charge-stockto a reforming operation can be employed in theprocess of this invention. As is well known, petroleum naphtha's; particularly those having a boiling range of from about 125 F. to about 450 F. and a-relatively low octane number rating,-. are the conventional charge stocks for reforming processesof the typecontemplated herein. Accordingly-,the charge stock may be an intermediate type naphtha, i. e., one containing an average distribution" of hydrocarbon types (parafiins,:olefins, naphthenes and aromatics) or one Which is' exceptionally high in paraifins, naphthenes or aromatics.
The temperatures to be used in the process of thepresentinventionvary between about 900 F. and about? 1050" F., preferably, between about 975 Rand about 1025 F. The total pressures vary, between'about pounds-per square inch gauge and about 750 pounds per square inch gauge, preferably, between about 400 pounds per square inch gauge and about 600 pounds per square-inch gauge; The mole ratios of hydrogen to naphtha vary between about 1:1 and about 10:1, respectively, preferably, between about 3:1 and; about 621, respectively. The liquid hourly space'velocities vary between about 0.5 and about 5 and, preferably, between about 2 and about 4.
The process can be caried out by making use of any of the well known techniques for operating catalytic reforming reactions in the vapor phase effectively. The reaction zone can be a chamber of any: suitable type useful in contact-catalytic operations, for example, a catalyst bed contained in a shell, or a shell in which the catalyst is disposed. ina series of'beds, through which the hydrocarbons arepassed in either upward or downward flow. The hydrocarbon vapors are maintainedinconta'ct with the catalyst at a predeterminedelevated temperature and for a predetermined period'of time, as set forth hereinbefore, and the resulting reaction mixture is passed througha condensing zone into a receiving chamber. It will -be understood that the hydrogen can be'recycled to the process.
It will be apparent-that the process can be op eratedas abatchor discontinuous process as by using a catalyst-bed-type reaction. chamber in whichthecatalytic and regeneration operations alternate. With aseries of such reaction chamhers;- it. Wil1-ber seen that as the catalytic operation is-taking place in one or more of the reaction chambers, regeneration of the catalyst will be tak inge place in. one" or more of the other reaction chambers. correspondingly, the process may be continuous when one or more catalyst chambers through which the catalyst flows in contact with the hydrocarbon vapors is used. Insuch a continuous process, the catalyst will flow through the reaction zone in contact with the hydrocarbon vapor-sand. will thereafter be separated from the hydrocarbonvapors. as, for example, by accumulating the catalyston a suitable filter medium, beforecondensing the. reactionmixture. In a continuous process, therefore, thecatalyst, fresh orregenerated, and the hydrocarbon vapors, fresh or recycled; will flow continuously through a reaction chamber.
The following detailed examples are for the purpose of. illustrating. the catalysts contemplated herein andtoindicate-the=advantages and characteristicsthereof,and, also, for the purposev of showing-smodes of carrying outthe process of this invention. It must be appreciated, however, that the invention is not to lbeicons'trued as being limited to the specific catalysts, methods of catalyst preparation, and charge stocksdisclosed herein.
after or to the specific manipulations and con- 10; amphoteric metals which obviated problems of hydrolysis and introduction of anions not decomposed by oxidation was impregnation with an acidic solution of the metal salt, precipitation of the metal as sulfide by re-impregnation with amditions set forth in the examples. As those skilled monium sulfide, followed by washing, drymg and in the art will readily understand, numerous calcination in air for 3 hours at 950 1 .130 conmodifica-tions and .variationstherein, all within vert the sulfide to the oxide. The salts of the the purview of the foregoing discussion, are possiamphoterie metals 1 used were stannous chloride ble and, accordingly, must be considered to b011 acidified with hydrochloric acid to form a clear encompassed by. the scope of ,the present invensolution, antimony trichloride and bismuth nition. I trate acidified with nitric acid solution to give EXAMPLES 1-ll V a clear solution.
All the catalysts were prepared using chromiahalf f q g m i' prep alumina beads obtained in accordance with the 10 9 1 5 i i 1 he procedure disclosed in "application for patent Sep Q me a 9 8 per mo c rial No. 201,537, filed by Stover and Wilson onwas f h impregnated W 5 gram atom December 14, 1950, referred to hereinbefore. 9 fluorine per 0 1 of mf by soak- Briefly, the procedure comprises rapidly mixing mgbthe beads m Just Summon F be a solution of sodium aluminate' (containing the tcompletelyf g ,bolutton g the equivalent of 2.65 moles A1203 per liter) with a 23 cu a g amount 2 g q fiuollqe to solution of chromic acetate (containing the ag i g Q g a equivalent of 0.75 mole 01203 per liter) in a mixt e 71 gg g f g W at ing nozzle to form a cli'romia-alumina hydrosoL' pe m a 9 The hydrosol fiows over a divider to form dropon drymg oven ,then hfaatedi m hydlogen lets and" these fall through a column of oil. Dur-' t at gradually mcreastng temperatures up ing the descent throughthe column of 011, the hy- 9 2 f f f f finally drosol droplets assume a' spherical shape before (me or ours e y rogen S m setting to a firm hydrogel, thereby producing Cata1yst evaluation was effected in conven- Spherical hydrogel beads. The'beads e then tional, stainless steel isothermal reactors, at 'temaged in an aqueous solution of ammonium sul- FP of 1000 at. liquid hourly space fate washedfree anions dried in steam and, locities of l. The charge stock used was a light finally, calcined at a temperature of 1000 F. Oklahoma City naphtha havmg the following These beads approximate the composition; plopertles' v mo 1,1 ;7 (moles) Inltlal boiling pomt 158 F.
- 10 -1;... at 175 F.
The catalysts were prepared by treatment of EJ319055, dry, calcined beads with aqueous solutions con- 90% taining the calculated amounts of desired com- 'End pom-t ""1 H 5 ponent, assuming complete' absorption, in just 40' CFRR z g iga enough water to be completely absorbed.
In alLcases, 0.03 gram atom of the metal pe For convenience, the pertinent data are set forth mole of chromia-alumina [one mole chromiain the following table;
Table AVERAGE OF TWO ONE-HOUR TESTS WITH REGENERATED CATALYSTS Atmospheric Pressure 131Ei 1%%if?ii%ifi fi?i tl 1:, Example orzoag Ai Fn 7e Gil-Free OFRR (la-Free CFRR Gas, Wt. Coke, Wt. Gasoline, Octane Gas, Wt. Coke, Wt. Gasoline, Octane Percent Percent Vol. 0., Percent Percent Vol. No.,
Percent Clear Percent Clear 17. 5 10. 0 09. 0 87.0 19. 4 0. 1 7s. 5 s1. 5 14. 2 0. 5 75. 5 s9. 0 18.5 0. 1 s0. 5 70. 5
12.8 9. e 73. 0 so. 5 1e. 2 0. 1 s2. 5 75. 0
14. s 10. 2 70. 5 92. 5 17. 2 0. 1 s1. 0 7s. 0
14. 4 11. 7 70. 0 as. 5 22. 3 0. 1 75. 5 s2. 0
alumina is 0.24 mole CI'2O3 plus 0.76 mole A1203 (Cr2O3:A12O3-=24:76)] was used, For potassium and calcium, the metal nitrates were used because they decompose on ignition to form metal The result set forth in the table show that all the metals, includin potassium, calcium and the amphoteric metals, show a marked promoter action in the low-pressure runs. However, when oxides. A uniform technique for introducing the the same catalysts were evaluated under hydrogen pressure, the promoter'action became a'de 1. A catalyst which comprises from about percent by weight to about 70 per cent by weight of chromium oxide, calculated as chromium sesquioxide, from about 0.1 per cent by weight to about 2.0 per cent by weight of' fluorine, an amphoteric metal selected from the group consisting of tin, antimony and bismuth, in amounts varying from about 0.5 to about ,2 times the amount calculated to form the normal fluoride of the amphoteric metal in its lower valence, and the balance alumina.
2. A catalyst which comprises from about per cent by weight to about per cent by weight of chromium oxide, calculated as chromium sesquioxide, from about 0.2 per cent by weight to about 1.5 per cent by weight of fluorine, an amphoteric metal selected from the group consisting of tin, antimony and bismuth, in amounts varying from about 0.5 to about 0.75 times the amount calculated to form the normal fluoride of the amphoteric metal in its lower valence, and
from about 5 per cent by weight to about per cent by weight of chromium oxidecalculated as chromium sesquioxide, from about 0.1 per cent by weight to about 2.0 percent by weight of fluorine, an amphoteric metal selected from the group consisting of tin, antimony and bismuth, in amounts varying from about 0.5 to about, 2
times the amount calculated to form the normal fluoride of the amphoteric metal in its lower valence, and the balance alumina, at a temperature falling within the range varying between about 900 F. and about 1050 F., at a pressure falling within the range varying between about pounds per square inch gauge and about 750 pounds per square inch gauge, at liquid hourly space velocities varying between about 0.5 and about 5, and in the presence of hydrogen in amounts varying between about one mole of hydrogen per'mole of naphtha and about ten moles of hydrogen per mole of naphtha.
4. A process for efiecting reforming of petroleurn naphthas, which comprises contacting a petroleum naphtha with a catalyst comprising from about 10 per cent by weight to about 35 per cent by weight of chromium oxide, calculated as chromium sesquioxide, from about 0.2 per cent by Weight to about 1.5 per cent by weight of fluorine, an amphoteric metal selected from the group consisting of tin, antimony and bismuth, in amounts varying from about 0.5 to about 0.75 times the amount calculated to form the normal fluoride of the amphoteric metal in its lower valence, and the balance alumina, at a temperature falling within the range varying between about 975 F. and about 1025 F., at a pressure WILLIAM H. LANG. CARLOS n. GUTZEIT. References Cited in the file of this patent UNITED STATES PATENTS Name Date Mattox Sept. 23, 1947 Number