US2313162A - Treatment of hydrocarbons - Google Patents

Description

Patented Mar. 9, 1943 TREATMENT OF HYDROCARBONS Jacque O. Morreli and Aristid V. Grosse, Chicago,

IlL, assignors to Universal Oil Products Company, Chicago, 111., a corporation of Delaware No Drawing. Application March 25, 1939. Serial No. 264,207

14 Claims.

This invention relates particularly to the treatment of aliphatic or straight chain hydrocarbons which are either completely saturated, as in the case of the paraflinic hydrocarbons, or straight chain hydrocarbons which may be unsaturated to the extent of their possessing one double bond between carbon atoms, as in the case of the monoolefinic hydrocarbons. The invention is directed primarily to the treatment of aliphatic hydrocarbons having less than 6 carbon atoms in straight chain arrangement, including ethane, ethylene, propane, propylene, butanes, butylenes, pentanes, and amylenes, although it may also be applied to hydrocarbons of more than six carbon atoms. The present application is a continuation-in-part of our earlier application Serial No. 105,714, filed October 15, 1936.

In a more specific sense the invention is concerned with a new and improved type of process for controllably increasing the degree of unsaturation in hydrocarbons of the character mentioned so that, for example, a paraflin hydrocarbon may be converted either into its correspondactions.

The present process is concerned with the more efiicient utilization of aliphatic hydrocarbons of the types mentioned above in that they are converted by dehydrogenation into compounds of a more reactive character which are readily utilizable in the production of polymers and miscellaneous hydrocarbon derivatives useful in the arts.

In the complete utilization of petroleum to form maximum yields of automotive fuel there is a considerable production of gaseous parafiinic hydrocarbons which are dissolved in the crude oils as produced and evolved as a light cut in the production of straight rung gasoline and there are further quantities of similar paraflinic gases produced in connection with the natural gas and natural gasoline industries. These gases are too volatile for direct utlization as motor fuel except in special instances, and at the present time their principal use is as domestic fuel. Owing to their generally unreactive character, it is difficult to transform them into increased yields of motor fuel unless they are converted into their corresponding oleflnic counterparts by splitting oif a molecule of hydrogen. After this is done the resulting olefins may be polymerized either by heat alone or by heat and catalysts to form gasoline boiling range polymers which are of high antiknock value and eminently suitable as blending fluid for increasing the knock-rating of straight run gasolines which are usually inferior in this respect.

In applying the present invention to the manufacture of mono-olefins from normally gaseous paraflins, the invention is related to processes involving the more complete utilization of the gases produced in connection with the production and refining of petroleum since the oleflnic gases are readily polymerizable by various thermal and catalytic methods to produce liquid polymers having a relatively high octane rating and boiling within the range of gasoline and which may be either utilized as such or hydrogenated to'corresponding liquid paraiilns. Thu according to the present process the residual parafllns remaining after the oleflns primarfly present in cracked gas mixtures have been polymerized, may be subjected to the treatment to produce additional quantities of polymerizable oleflns.

In the process for manufacturing dioleflns either from parafilns or mono-olefins according to the present process the invention is related to the synthetic rubber problem in that butadienes and their alkylated derivatives are producible from 4 and 5 carbon atom aliphatic hydrocarbons and these butadienes are polymerizable to form high molecular weight polymers closely resembling natural rubber.

In experimenting with methods and conditions for converting paraflin hydrocarbons into olefins by dehydrogenation, a co siderable number of catalytic materials have been tried with greater or lesser effectiveness, since it has been found generally that better results in the matter of yield of olefins without the formation of liquid and gaseous by-products are obtainable by the use of catalysts rather than by the use of heat alone, and furthermore that under proper catalytic influences temperatures, pressures, and time factors are lower, so that less expensive apparatus may be employed and greater capacities insured.

In one specific embodiment the present invention comprises the treatment of parafllnic ormono-olefinic hydrocarbons for the dehydrogenation thereof by subjecting said hydrocarbons at temperatures of the order of 450-700 C. and relatively low pressures to contact with solidagranular catalysts consisting essentially of aluminum oxide mixed with or supporting oxides of the elements in the left-hand column of group V of the periodic table, which oxides have been found to have relatively high catalytic activity in furthering straight dehydrogenation reactions.

The present invention is characterized by the use of particular catalytic materials and suitable combinations of temperature, pressure, and time of contact to control the character and extent of the dehydrogenation of aliphatic hydrocarbons to produce a minimum of undesirable by-products. Temperatures from approximately 450 to 700 C. may be employed, pressures from moderately superatmospheric of the order of '50 to 100 lbs. per square inch-down to those of the order of 0.25 atmosphere absolute or lower and times of contact from approximately 0.01 to seconds. In the case of the dehydrogenation of parafflnic hydrocarbons to produce the corresponding mono-oleflns, temperatures within the approximate range of 450 to 650 may be employed, atmospheric pressures and times of contact of the order of 0.1 to 6 seconds. When producing diolefins from mono-olefins, temperatures from 500 to 700 C. are preferred, absolute pressures of approximately 0.25 atmosphere and times of contact of less than 1 second. When it is desired to produce diolefins directly from parafiins without a primary stage involving the production and segregation of the mono-olefins, intermediate conditions of operation may be employed which will be more or less fixed by the molecular weight and constituents of the paramn or mixture of parafllns to be subjected to treatment.

In accordance with the present invention, the catalysts which are preferred for selectively dehydrogenating aliphatic hydrocarbons have been evolved as the result of a large amount of investigation with catalysts having a. dehydrogenating action upon various types of hydrocarbons such as, for example, those which are encountered in the fractions produced in the distillation and/or pyrolysis of petroleum and other naturally occurring hydrocarbon oil mixtures. The criterion of an acceptable dehydrogenating catalyst is that it shall split off hydrogen without inducing either scission of the bonds between carbon atoms or carbon separation.

It should be emphasized that in the field of catalysts there have been very few rules evolved which would enable the prediction of what materials will catalyze a given reaction. Most of the catalytic work has been done on a purely empirical basis, though at times certain groups of elements or compounds have been found to be more or less equivalent in accelerating certain types of reaction. For example, the noble metals, platinum and palladium, have been found to be efiectivein dehydrogenating reactions, particularly in dehydrogenating naphthenes to form aromatics, but these metals are expensive and easily poisoned by traces of sulfur so that their use is considerably limited in petroleum hydrocarbon reactions.

The present invention is characterized by the use of a particular group of composite catalytic materials which contain aluminum oxide which in itself has some catalytic ability in the dehydrogenating reactions but which is improved greatly in this respect by the addition to or admixture therewith of certain other catalysts (most generally in minor proportions), which comprise in the present instance the oxides of the elements in the left-hand column of group V of the periodic table which include vanadium, columbium, and tantalum. 7

It is essential to the preparation of these active and selective dehydrogenative catalysts that .the aluminum oxide used possess certain structural characteristics permitting the maintenance on its surface and in its poresoi a stable deposit of the more active oxide catalysts which is essentially undisturbed under the conditions of operation and when regenerating by burning of! carbonaceous deposits with air or other oxygencontaining gas mixtures.

The more active compounds or promoters which are used in the catalyst composites according to the concepts of the present invention include the oxides of vanadium, columbium and tantalum which constitute a natural group since they are the elements in the left-hand column of group V of the periodic table. While the oxides of these elements are effective catalysts in the dehydrogenation reactions, it is not intended to infer that the different oxides of any one element or the corresponding oxides of the different elements are exact equivalents in their catalytic activity.

Catalystcomposites may be prepared by utilizing the soluble compounds of the elements containing a volatile radical in aqueous solutions from which they are absorbed by the prepared alumina or from which they are deposited upon the alumina by evaporation of the solvent, after which the volatile radical is driven off by heat. The invention further comprises the use of catalyst composites made by mixing compounds of the above-mentioned character or prepared oxides with the alumina either in the wet, dry or fused condition. In the following paragraphs some of the compounds of the elements listed above are given which may be used to add the catalytic oxides to the alumina. The known oxides of these elements are also listed.

VAN ADIUM Catalysts comprising alumina and up to 25 per cent by weight of the lower oxides of vanadium such as the sesquioxide V203 and the tetroxide V204 may be effectively used. Some of the monoxide V0 may be present in some instances. Thus solutions of the ammonium vanadate may be employed to add vanadium oxides to the alumina and also the soluble vanadyl sulfates and the vanadium nitrate and carbonate. The oxides per se or those produced by reduction or decomposition of other vanadium compounds may be used.

COLUMBIUM A properly prepared alumina may be ground and sized to produce granules of relatively smill mesh of the approximate order of from 4 to 0 and these caused to absorb compounds which will ultimately yield oxides of columbium on heating to a proper temperature by stirring them with warm aqueous solutions of soluble columbium compounds. The oxide resulting from the decomposition of such compounds as the pentahydroxide is for the most part the pentoxide CbzOs. This oxide, however, is reduced to a definite extent by hydrogen or by the gases and vaporous products resulting from the decomposition of the paraflins treated in the first stages of the process, so that the essential catalysts for the larger portion of the period of service are evidently the lower oxides CbOa, Chaos, and C100.

TANTALUM Compounds of tantalum, such as for example, the pentoxide TaaOs and the tetroxide TaaO4, and possibly the sesquioxide TazOa, which result from the reduction of the pentoxide and particularly eiilc ient as catalysts mthe present types of reactions. Tantalum fluoride is. soluble in 'water and may be conveniently used in result from the ignition of the precipitatedhydrox'ide to form the pentoxide, the partial reductlon of this oxide by hydrogen or the gases and vapors in contact with the catalyst in the normal operation of the process forming the desired lower oxides. The tantalum pentahydroxide may be precipitated from a solution of the fluoride by the use of ammonium or alkali metal hydroxides or carbonates as precipitants, the hydroxide being later ignited to form the pentoxide. which may undergo some reduction as already stated.

Aluminum oxides prepared by careful calcination of certain natural hydroxides and carbonates and by carefully regulated chemical precipitation of aluminum hydroxide followed by calcination are practically always good supporting materials for the preferred dehydrogenating oxides -in accordance with the present invention. While some forms of alumina may have in themselves some slight dehydrogenating activity, an extensive series of experiments has definitely shown that any inherent catalytic property which difierent forms of prepared alumina may have may be greatly increased by the addition of oxides of the present character in amounts usually of the order of less than of the total composite of alumina and the oxide.

Aluminum oxide suitable as the base material for the manufacture of catalysts for the process may be obtained from some natural aluminum oxide minerals or ores such as bauxite or carbonates such as dawsonite by proper calcination, prepared by precipitation of aluminum hydroxide from solutions of aluminum sulfate, nitrate, chloride, or different other salts, and dehydration of the precipitate of aluminum hydroxide by heat. Usually it is desirable and advantageous to further treat it with airor other gases, or by other means to activate it prior to use.

Three hydrated oxides of aluminum occur in nature, to wit, hydrargillite or gibbsite having the formula AlzOaBI-IsO, bauxite having the formula A12.O3.2H2O, and diaspore having the formula A1203.H2O. Of these three minerals the corresponding oxides from the trihydrated and dihydrated minerals are suitable for the manufacture of alumina for the present type of cats,-

lysts and these materials have furnished types of activated alumina which are entirely satisfactory. Precipitated trihydrates can also be dehydrated at moderately. elevated temperatures to form satisfactory alumina supports.

It is best practice in the final steps of preparing substantially anhydrous aluminum oxides for use in the catalyst composites to ignite them for some time at temperatures within the approximate range of from SOD-900 C. This does not correspond to complete dehydration of the hydrated oxides but gives catalytic materials of good strength and porosity so that they are able to resist for a long period of time the deterioraing effects of the service and regeneration periods to which they are subjected.

While other forms of aluminum oxide may be used, it is of considerable advantage to employ the type of aluminum oxide known as gammaalumina, by which is meant the modification obtained by the dehydration of the monohydrate termed bohmite (Al0.0I-I) or the trlhydrate aqueous solutlon'as a source of the oxides which AKOB): termed hydrarglllite (or gibbsite. when occurring in nature). at temperatures above 250' C. and preferably of the order of 850-500 C. until a substantial equilibrium is established corresponding to the-remova of substantially all of the water and the formation of crystals falling withinthe regular or cubic classification. Gamma-alumina is characterized by definite crystallographic properties and can be readily distinguished from the large number of other modifications of alumina. such as alpha. beta, epsilon, zeta, etc..' by its X-ray diflraction pattern. The gamma-alumina crystallizes in the cubic system with the edge of the unit cube bein about 7.9 Angstrom units.

' The most general method for adding the more active oxides to the prepared activated alumina, which. has a high adsorptive capacity, is to stir the prepared granules of from approximately 4 to 20 mesh into solutions of salts which will yield the desired promoting oxides on ignition under suitable conditions. In some instances the granules may be merely stirred in slightly warm solutions of salts until the dissolved compounds have been retained on the particles by absorption or occlusion, after which the particles are separated from the excess solvent by settling or filtration, washed with. water to remove excess solution, and then ignited to produce the desired residual oxide. In cases of certain compounds of relatively low solubility it may be necessary to add the solution in successive portions to the alumina with intermediate heating to drive off solvent in order to get the required quantity of oxide deposited upon the surface and in the pores of the alumina. The temperatures used for drying and calcining after the addition of the promoters from solutions will depend entirely upon the individual characteristics of the compound added and no general ranges of temperatures can be given for this step.

In some instances promoters may be deposited from solutions by the addition of precipitants which cause the deposition of dissolved materials upon the alumina granules. methods of mechanical mixing are not preferable, though in some instances as in the case of hydrated or readily fusible compounds these may be mixed with the proper proportions of alumina and uniformly distributed during the condition of fusing or fluxing.

Catalysts composites may be made by mixing alumina powders with the preferred oxides, by depositing hydroxides upon alumina powders suspended in solutions of the salts of the we ferred metals, by absorbing aqueous acids or nitrates upon alumina powder or by co-precipitation of aluminum hydroxide and metal hydroxides, after which the dried and powdered materials are pelleted in any standard type of machine. Any obvious procedure necessary to obtain a pellet of uniform characteristics may be employed and any minor amount of lubricant may be used which is effective in preventing sticging or abrasion of the parts of the machine use In regard to the relative proportions of ing all economic features. The effect upon the catalytic activity of the alumina caused by varying the percentage of any given oxide or mix-- Asarule' nation by experiment.

ture of oxides deposited thereon is not a matter for exact calculation but more one for determi- Frequently good increases in catalytic effectiveness are obtainable by the deposition of as low'as 1% to 5% of an oxide upon the surface and in the pores of the alumina, though the general average is about In practicin hydrocarbons according to the present process a solid composite catalyst prepared accordingv to the foregoing alternative methods is used as filler in a reaction tube or chamber in the form of particles of graded size or small pellets and the hydrocarbon gas or vapor to be dehydrogenated is passed through the catalyst after being heated to the proper temperature, under a definite pressure and for a time of contact adapted to produce the results desired. The catalyst tube may be heated exteriorly if desired to maintain the proper reactiomtemperature.

As an alternative and frequently preferable method of operation with the present types of catalysts, they may be used as refractory filling material in the form of bricks or special forms or as a coating upon bricks or other forms in furnaces of the regenerative type which are alternately blasted and then used as heating means to effect the desired conversion reactions. In such an operation a regenerative chamber may be filled with alternate layers of ordinary non-catalytic refractory forms and layers of catalytic materials. In this method of operation the heat necessary for the dehydrogenation reactions is added during the regenerating period which must be employed in any event to periodically remove carbonaceous deposits from the catalyst surfaces.

It has been found essential to the eillclent and selective dehydrogenation of aliphatic hydrocarbons when using the present types of catalysts that the gaseous or vaporized materials be substantially free from water vapor. If appreciable amounts of steam are present, the catalytic activity is adversely affected so that the active life -is shortened, the need for regeneration becomes more frequent and a point is more quickly reached where regeneration is no longer effective. The reasons for this phenomenon are not entirely clear but may possibly be due to a certain degree of hydration of the more active catalytic components of the mixtures or the hydration of the aluminum oxide support.

The exit gases from the tube or chamber may be passed through selective absorbents to combine with or absorb the unsaturated hydrocarbons produced. Mono-olefins may be selectively polymerized by suitable catalysts, (caused to alkylate other hydrocarbons such as aromatics or treated directly with chemical reagents to produce desirable and commercially valuable derivatives. Di-olefins or cli-olefm derivatives may be catalytically condensed or polymerized to form synthetic rubber products as already mentioned. After the olefins have been removed the residual gases may be recycled for further dehydrogenating treatment with or without removal of hydrogen.

Members of the present group of catalysts are selective in removing two hydrogen atoms from aliphatic hydrocarbon molecules to produce the corresponding straight-chain unsaturated products without furthering to any great degree undesirable side reactions, and because of this show the dehydrogenation of aliphatic amazes I y p an unusually long period'of activity in service as will be shown in later examples. :When', how;

ever. their activity begins to diminish it 'is readily regenerated by the simple expedient'of'o'xidizing with air or other oxidizing gasat'a'moderatelyx elevated temperature, usually within the range: employed in the dehydrogenating reactions. This oxidation effectively removes'traces" of. carbon deposits which contaminate the surface of the" particles and decrease their emciency. It is characteristic of the present types of catalysts that they may be repeatedly regenerated witho'ut' material loss of porosity or catalyzing eillcieney.

The following examples are given to indicate the selective character of the dehydrogenation reactions produced by catalysts comprised within the present group, though they are merely selected from a large number and not given with the intent of unduly limiting the scope of the invention.

EXAMPLE I The catalyst was prepared by dissolving 16' parts by weight of ammonium metavanadate in 200 parts by weight of hot water and adding the solution in two equal successive portions to 200 parts by weight of a 10-12 mesh activated alumina. After the addition of the first half of the solution the particles were somewhat damp and were dried at a steam temperature to remove excess water. After the heating, the second half of the solution was added and the dehydration repeated. During the heating period ammonia and water were evolved leaving vanadium pentoxide deposited on the alumina particles.

In this case a mixture of parafiinic gases constituting the residue after the polymerization of the olefins in a cracked gas mixture was the starting material. This gas consisted of 10% propane, 45% n-butane, and 45% isobutane. The gas mixture was passed over the catalyst at atmospheric pressure and a temperature of 500 C.

The following table shows the composition of the outlet gases at different times in the run.

Composition of exit gases Time after start, hours 22 '72 i-Butylene 13 15 1"! Propylene and n-buty1enes '7 10 8 Ethylene l 1 1.5 Total higher olefins 20 25 25 Hydrogen 30 27 An examination of the above data indicates the high degree of selectivity of the present type of catalyst, since the percentage by volume of hydrogen is approximately equivalent to the production of higher olefins, and there is a very small percentage of ethylene present.

EXAMPLE II Owing to the relative insolubility of most of the compounds of tantalum the method of dry mechanical mixing was resorted to in making up a catalyst thus one part by weight of tantalum dioxide was mixed with about 10 parts by weight of activated alumina which had been produced by calcining bauxite at a temperature of about 700 C., followed by grinding and sizing to produce particles of approximately 8-12 mesh. The catalyst particles were not treated with hydrogen on account of the known difllculty in reducing tantalum oxide although some reduction evidently took place when'the hydrocarbon gas was atmospheric pressure and 600 C. with contact times of 1 to 2 seconds, the composition of the exit gases obtained during a run being shown below:

. Per cent Propylene 24, I-llydrogen 25 Methane 1.0 Propane 50 Ethyl n 0.5 This gas composition was substantially unchanged after three successive regenerations.

Exam ne III A catalyst was prepared by dissolving 15.4 parts by weight of ammonium metavanadate in 200 parts by weight of hot water and adding the solution in two equal successive portions to 200 parts by weight of a to 12 mesh activated alumina. After the addition of the first half of the solution the particles were somewhat damp and were dried at a steam temperature to remove excess water. After this heating the second half of the solution was added and the dehydration repeated. During the heating'period ammonia and water were evolved leaving vanadium pentoxide deposited on the alumina particles.

The final steps in the preparation of the catalyst comprised heating at 200-250 C. for-several hours, adding the particles to a catalyst chamber in which they were brought'up to the necessary reaction temperature for dehydro-' genating a mono-olefinic gas mixture in a current of air, and. then subjecting them to the action of hydrogen at the operating temperature to produce the lower oxides, this change yellow to bluish gray.

Using the catalyst prepared in the above manner a mixture of approximately equal parts of alpha .and beta butylenes was dehydrogenated at a temperature of 610 C., a pressure of 0.25 atmosphere and a contact time of 0.7 second. In the products which were condensed by cooling at -80 C., 1,3-butadiene was found to be present in a concentration of about 37 per cent,

' corresponding to a yield of about 21 per cent based on the materials charged. The identification was made by means of the reaction with maleic anhydride, and further identification was made by the formation of the compound: 1,2,23,4- tetrabromobutane.

EXAMPLE IV A catalyst was prepared for use in dehydrogenation of mixtures of alpha and beta butenes as representing mono-olefins. Owing to the relative insolubility of most of the compounds of tantalum the method of dry mechanical mixing was resorted to in making up a catalyst. Thus three parts by weight of tantalum dioxide was mixed with about parts by weight of activated alumina which had been produced by calcining bauxite at a temperature of about 700 C., followed by grinding and sizing to produce particles of approximately 8-12 mesh. The catalyst particles were not treated with'hydrogen on account of the known difliculty in reduc ng tantalum oxide although some reduction evidently took place ner a mixture of approximately equal parts of alpha and beta butylenes was dehydrogenated at a temperature of 615- 0., a pressure of 0.25,

atmosphere and a contact time of 0.80 second.

In the products which were condensed by cooling at -80 C., 1,3-butadiene'was found to be present in a concentration of about 36 per cent, corresponding to a yield of about 22 per cent based on the materials charged. The identification was made by means of the reaction with maleic anhydride, and further identification was made by the formation of the compound:

.40 being accompanied by change in color from 1,2,3,4-tetrabromobutane.

The foregoing specification and examples show clearly the character of the invention and the results to be expected in its application to allphatic hydrocarbons, although neither section is intended to be unduly. limiting.

We claim as our invention:

l. A process for the dehydrogenation of allphatic hydrocarbons having less than six carbon atoms in straight-chain arrangement to produce unsaturated derivatives thereof, which comprises subjecting said aliphatic hydrocarbons at a temperature of the order of 450-700 0., absolute pressure of the order of 0.25 to 7 atmospheres, and time from approximately 0.1 to 10 seconds to contact with a solid granular catalyst comprising essentially aluminum oxide which has a relatively low catalytic activity supporting an oxide which has a relatively high catalytic activity selected from the group consisting of the oxides of vanadium, columbium and tantalum.

.2. A process for the dehydrogenation of aliphatic hydrocarbons to produce unsaturated derivatives thereof, which comprises subjecting said aliphatic hydrocarbons at a temperature of the order of 450-700 0., absolute pressure of the order of 0.25 to '7 atmospheres, and'time from approximately 0.1 to 10 seconds to contact with a solid granular catalyst comprising essentially activated aluminum oxide which has a relatively low catalytic activity supporting an oxide which has a relatively high catalytic activity selected from the group consisting of the oxides of vanadium, columbium, and tantalum.

3. A process for the dehydrogenation of paramn hydrocarbons to produce diolefins therefrom, which comprises subjecting said paraffln hydrocarbons at a temperature of the order of 500-700 C. subatmospheric pressure and time of the. order of 0.01 to 2 seconds to contact with a solid granular catalyst comprising essentially aluminum oxide which has relatively high catalytic activity selected from the group consisting of the order of 0.01 to 2 seconds to contact with a when the hydrocarbon gas was passed over the solid granular catalyst comprising essentially activated aluminum oxide which has relatively low catalytic activity supporting an oxide which has relatively high catalytic activity selected from the group consisting of the oxides of vanadium, columbium and tantalum.

5. A process for the dehydrogenation of parafiin hydrocarbons to produce diolefins therefrom, which comprises subjecting said parafiin hydrocarbons at a temperature of the order of 500-700 C. subatmospheric pressure and time group consisting of the oxides of vanadium,

columbium and tantalum.

6. A process for the dehydrogenation of allphatic hydrocarbons to produce unsaturated derivatives thereof/which comprises subjecting said aliphatic hyi'iroc'arbons at atemperature of the order of 450-700" C., absolute pressure of the order of 0.25to'7 atmospheres, and time from approximately 0.1 to 10seconds to contact with a solid granular catalyst comprising essentially aluminum oxide which has a relatively low catalytic activity supporting vanadium oxide which has a relatively high catalytic activity.

7. A process for the dehydrogenation of allphatic hydrocarbons to produce unsaturated derivatives thereof. which comprises subjecting said aliphatic hydrocarbons at a temperature of the order of 450-700 C., absolute pressure of the order of 0.25 to 7 atmospheres, and time from approximately 0.1 to 10 seconds to contact with a solid granular catalyst comprising essentially aluminum oxide which has a relatively low catalytic activity supporting columbium oxide which has a relatively high catalytic activity.

8. A process for the dehydrogenation of allphatic hydrocarbons to produce unsaturated derivatives thereof, which comprises subjecting said aliphatic hydrocarbons at a temperature of the order of 450-700 .C., absolute pressures of the-order of 0.25 to 7 atmospheres, and timefrom approximately 0.1 to 10 seconds to contact with a solid .granular catalyst comprising essentially aluminum oxide which has a relatively low catalytic activity supporting tantalum oxide which has relatively high catalytic activity.

9. A process for the dehydrogenation of paraflin hydrocarbons to produce -dioleflns therefrom, which comprises subjecting said paramn hydrocarbons at a temperature oi. the order of 500-700 C. subatmospheric pressure and time of the order of 0.01 to 2 seconds to contact with a solid granular catalyst comprising essentially aluminum oxide which has relatively low catalytic activitysupporting columbium oxide-which has relatively high catalytic activity.

10. A process for the dehydrogenation of paraflin hydrocarbons to produce dioleflns therefrom, which comprises subjecting saidparaflin hydrocarbons at a temperature of the order of 500-700 C. subatmosphoric pressure and time or the order or 0.01 to 2 seconds to contact with a solid granular catalyst comprising essentially aluminum oxide which has relatively low catalytic activity supportingtantalum oxide'which has relatively high catalytic activity. 11. A process for dehydrogenating aliphatic hydrocarbons which comprises contacting the same under dehydrogenating conditions with an oxide or an element from the left-hand column of group 5 of the periodic table, supported on an activated alumina comprising a calcined aluminum hydrate of high adsorptive capacity.

12. A process for dehydrogenating aliphatic hydrocarbons having less than sixcarbcn atoms in straight chain arrangement which comprises contacting the same under dehydr'cgenating conditions with an oxide of an element from the left-hand column or group 5 of the periodic table, supported on an activated alumina comprising a calcined aluminum hydrate of high adsorptive capacity.

13. A process for dehydrogenating paraflinic hydrocarbons which comprises contacting the same under dehydrogenating conditions with an oxide of an element from the left-hand column of group 5 of the periodic table, supported on an activated alumina comprising a calcined aluminum hydrate of high adsorptive capacity.

14. A process for converting normally gaseous paraflins to olefins which comprises contacting the paraflins under dehydrogenating conditions with an oxide of an element from the left-hand column of group 5 of the periodic table, supported on an activated alumina comprising a calcined aluminum hydrate of high adsorptive capacity.

' JACQUE C. MORRELL.

ARIS'I'ID V. GROSSE.