US2625504A - Catalytic reforming process and catalyst therefor - Google Patents

Description

Patented Jan. 13, 1953 CATALYTIC REFORMING PROCESS AND CATALYST THEREFOR Vladimir Haensel, Hinsdale, Ill., and Curtis F.

Gerald, Woodinville, Wash., assignors to Universal Oil Products Company, Chicago, 111., a

corporation of Delaware No Drawing. Application March 28, 1951, Serial No. 218,066

13 Claims. 1

This application is a continuation-in-part of application Serial No. 104,798, filed July 14, 1949, which in turn is a continuation-in-part of application Serial No. 717,659, filed December 21, 1946, Patent 2,478,916, issued August 16, 1949.

This invention relates to a reforming process and more particularly to a process for the reforming of a gasoline fraction in the presence of a particular catalyst and under selected conditions of operation.

The gasoline fraction to be treated in accordance with the present invention preferably comprises a saturated gasoline fraction including straight run gasoline, natural gasoline, etc.

The gasoline fraction may be a full boiling range gasoline having an initial boiling point within the range of about 50 to about 90 F. and an end boiling point within the range of about 375 to about 425 F., or it may be a selected fraction thereof which usually will be a higher boiling fraction, commonly referred to as naphtha, and generally having an initial boiling point of from about 150 to about 250 F. and an end boiling point within the range of about 350 to about 425 F.

The term reforming is well known in the petroleum industry and refers to the treatment of gasoline fractions to improve the antiknock characteristics. Straight run gasolines contain naphthenic hydrocarbons, particularly cyclohexane compounds, and parafiinic hydrocarbons which usually are of straight chain or slightly branched chain structure, as well as varying proportions of aromatic hydrocarbons. In order to obtain best results in reforming operations it is desired to dehydrogenate the naphthenic hydrocarbons to produce aromatics, to cyclisize the straight chain parafilnic hydrocarbons to form aromatics, as well as to effect a controlled type of cracking which is selective both in quality and in quantity. In addition, various other concomitant reactions occur such as isomerization, hydrogen transfer, etc.

The cracking or splitting of carbon to carbon bonds is one of the important factors in a successful reforming process. Controlled or selective cracking is highly desirable since such cracking will result in a product of improved antiknock characteristics. In general, the lower molecular weight products have higher octane numbers, and thus a final gasoline product of lower average molecular weight will usually have a higher octane rating. Further, during the cracking reaction, isomerization or other molecular rearrangement occurs which also results in products having higher antiknock characteristics. The selective cracking is also of particular advantage when the charging stock contains components boilingabove about 400 F. in order to convert these components to fractions boiling below about 400 F. It is thus seen that the selective cracking results not only in an improved quality product but also in an increase in quantity of the desired products.

However, the cracking must be selective and must not result in the decomposition of the normally liquid hydrocarbons substantially or completely into normally gaseous hydrocarbons. The desired selective cracking generally comprises splitting of the hydrocarbon molecule near the middle thereof. Also efiected is the removal of methyl, ethyl and, to a lesser extent, propyl groups, in the form of methane, ethane and propane as will be hereinafter described. However, the removal of these radicals is controlled so that not more than one or possibly two of such radicals are removed from a given molecule. For example, heptane may be reduced to hexane, nonane to octane or heptane, etc. On the other hand uncontrolled or non-selective cracking will result in the decomposition of normally liquid hydrocarbons into normally gaseous hydrocarbons as, for example, by the continued demethylation of normal heptane to produce 7 molecules of methane.

Another important objection to the non-selective or uncontrolled cracking is that this type of cracking will result in the more rapid forma tion of larger quantities of coke or carbonaceous material which deposits on the catalyst and decreases or destroys its activity to catalyze the desired reactions. This in turn results in shorter processing cycles or periods, with the necessity of more frequent regeneration of the catalyst by burning the carbonaceous products therefrom or, should the catalyst activity be destroyed, it will be necessary to shut down the unit to remove the old catalyst and replace it with new catalyst.

Another important feature in successful reforming processes is the matter of hydrogen production and consumption. Investigation has shown that the presence of hydrogen in the reforming zone further tends to decrease the amount of carbonaceous deposits on the catalyst. In view of the fact that the cost of hydrogen is quite high, it is preferable that there be no net consumption of hydrogen or, in other words, at least as much hydrogen must be produced in the process as is consumed therein.

In one embodiment the present invention relates to a process for reforming a gasoline fraction which comprises subjecting said fraction to contact at reformin conditions with a catalyst comprising alumina, boron oxide and a metal selected from the group consisting of platinum and palladium.

In a specific embodiment the present invention relates to a process for reforming a saturated gasolin fraction which comprises subjecting saidv fraction to contact at reforming conditions with a catalyst prepared by compositing from about 0.01% to about 2% by weight ofa metal selected from the group consisting of platinum and palladium with a cracking component.

In another embodiment the present invention relates to a process for reforming a straight run gasoline fraction which comprises subjecting said fraction to contact at reforming conditions with a catalyst prepared by compositing from about 0.2 gram to about 2 grams per 100 cc. of final catalyst ofa metal'selected from the group con-, sisting of platinum and palladium with a dry cracking component.

In another specific embodiment the present invention relates to a process for reforming: a straight run gasoline fraction which comprises subjecting said fraction to oontact'at a'temperature of from about 500 to about 1000 F. and a pressure of from about atmospheric to: 1000 pounds or more per square inch, at'an hourly liquid space velocity of from 0.1 to about 5 in the presence of'from about 0.1 to about rmolsof hydrogen, with a catalyst prepared by-composit-j ing from about 0.01% toabout 2% by weight of platinum with a dry' cracking component-com- 0 cracking. Therefore, it is an essential feature of the present invention that the concentration'of platinum or palladium in the catalyst shall be within the range herein set forth.

Due to the high cost of platinum andpalladium, a major factor in the use of catalysts containing these metals is the quantity to be'used. As will be noted, the improved process of the present invention requires small quantities of these metals. However, as, the densities of the different cracking components vary considerably, the quantity of platinum or palladium may be specified on the basic of grams thereof percubic centimeters of final'catalyst. The final catalyst charged to the process is usually determined as so much volume required to n11 a given'portion of the reaction zone, and this method of specifying the platinum or palladium concentration readily shows the quantity of these'metals required. When specified on thisrbasis, the ,prefered concentrations of platinum and palladium are from about 0.2 gram'to about 2 grams P813100 cc; of final catalyst However; it :is understood that the broader range of platinum or palladium concentration as hereinbefore set forth is from about 0.01% to about 2% by weight of the final catalyst and that this concentration when trans! lated into grams per 100cc. of final catalyst will vary with the densityof the particular-cracking catalyst employed.

The cracking component to be composited with the platinum or palladium may comprise any suitable cracking catalyst, either naturally occurring or synthetically produced. Naturally occurring cracking catalysts include various aluminum silicates; particularly when vacid treated to increase the activity, such as Super Filtrol, etc. synthetically produced cracking catalysts include silica-alumina, silica-zirconia, silica-alumina-zirconia, silica: magnesia, silica alumina magnesia, silica-alumina-thoria, alumina-boron-oxide, etc. These catalysts may be made in any manner includingseparate, successive or coprecipitation methods of manufacture. Preferred cracking catalysts comprise silica-alumina or silica-alumina-zirconia which are preferably manufactured by commingling an acid, such as hydrochloric acid, sulfuric acid, etc., with commercial water glass under conditions to precipitate silica, washing with acidulated water or otherwise to remove sodium ions, commingling with an aluminum salt such as aluminum chloride, aluminum sulfate, aluminum nitrate, and/ or zirconium salt, etc., and either adding a basic precipitant, such as ammonium hydroxide, to precipitate alumina and/or zirconia, or forming the desired oxide or oxides by thermal decomposition of the salt as the case may'permit. The silicaalumina-zirconia catalyst may be formed byadding the aluminum and/or zirconium salts together or separately. The catalyst may be in the form of granules of irregular size and shape or the groundgranules may be formed into pellets of uniform size and shape by pilling, extrusion or other suitable methods;

A particularly satisfactory method'of forming thecracking component is to add the acid to commercial water glass at a pH controlled to form silica hydrogel, discharging the mixture of acid and water glass from a rotating disc or nozzle into abath of oil of sufficient depth so that the silica hydrogel sets into firm spheres during passage through the oil bath. The spheres maybe removed from the bath in any suitable manner, such as by being transported in a stream of water disposed beneath the oil layer. The silica spheres may then be treated in any suitable manner to remove sodium ions, followed by impregnating with a solution of soluble metal salt or salts. In another embodiment silica-alumina spheres, silica-magnesia spheres, etc., may be formed by co-precipitating methods in a similar system.

The alumina-boron-oxide cracking component preferably contains from about 1% to about 15% by weight of boron-oxide. These catalysts are generally prepared by adding a suitable compound of boron such as'boron oxide, boric acid, etc. to alumina, in either the wet or dry condition, thoroughly mixing the components and then heating until the mixture is dry. In a preferred embodiment boric acid solution is added to pre cipitated alumina and then the mixture is thoroughlymixed and finally heated. In an alternative method, salts such as aluminum chloride hexahydrate, which decompose on heating to form the corresponding oxide, are intimately mixed, with boric oxide solution, and the mixture heateduntil the salt is decomposed to form the oxide. In another embodiment boric anhydride, boric acid or a perborate may be dissolved in water and then commingled with alumina and an alkaline precipitant, such as ammonium hydroxide, is added to precipitate the component, after which the precipitate is filtered, washed and dried. The alumina-boron-oxide composite may be formed into particles of definite size and shape in the manner herein set forth.

In general, water or steam will be excluded during the reforming process. However, if these are present, there may be a tendency for the boron-oxide to be removed from the catalyst and, in such cases, it is within the scope of the present invention to add a boron compound, preferably along with the charge, to replace the boron-oxide being lost. Any suitable boron com.- pound, such as ethylborate, boric acid, etc., may be utilized for this purpose.

Although the platinum or palladium may be composited with the cracking base before the latter has been partly or completely dried, it generally is preferable that the cracking component be dried at a temperature of at least 350 F. before the platinum or palladium is composited therewith. The cracking component may be dried at a temperature of from about 350 to about 500 F. and/or calcined at a temperature of from about 500 to about 1400" F. or more prior to admixing the platinum or palladium therewith.

The temperatures to be employed in the reformin operation will be within the range of from about 500 to about 1000 F. and preferably of from about 500 to about 875 F. Temperatures below 500 F. are too low for satisfactory conversions. Hydrocracking reactions are favored at temperatures of from about 500 to about 625 F. and at pressures within the range of from about 600 to 1000 pounds or more. Hydrocracking is defined as cracking or splitting of carbon to carbon bonds accompanied by satura- .,tion of the fragments so formed by hydrogen present in the reaction zone and, in accordance with the present invention, the hydrocracking will be selective both in quality and quantity as hereinbefore set forth. On the other hand, the aromatization reactions are favored at temperatures within the range of from about 600 to about 1000 F. and at lower pressures within the range of atmospheric to about 400 pounds per square inch.

It is an essential feature of the present invention that the temperature and pressure be correlated to produce the desired aromatization and selected hydrocracking. The exact temperature and pressure to be used in any given operation will depend upon the particular gasoline being treated, and also will be correlated with the hourly liquid space velocity. Hourly liquid space velocities (defined as the volume of liquid hydrocarbon oil per hour per volume of catalyst) willl be Within the range of from about 0.1 to about 5.

In one manner of operation of the process, sufficient hydrogen will be produced in the reforming reaction to saturate the hydrocarbon fragments formed therein and, therefore, it may be unnecessary to either introduce hydrogen from an extraneous source or to recycle hydrogen within the process. However, it usually will be preferred to either introduce hydrogen from an ex- .traneous source, generally at the beginning of the operation, and to recycle hydrogen within the process in order to assure a sufiicient hydrogen atmosphere in the reaction zone. Hydrogen serves to reduce carbon formation and thereby to lengthen the life of the catalyst.

The composite catalyst of the present invention may be prepared in any suitable manner, a preferred method comprising admixing chloroplatinic acid or chloropalladium acid in the desired amounts with the crackin component which previously had been dried and/or calcined in themanner hereinbefore set forth. 'Ihe'composite of platinum or cracking component is then dried or treated with hydrogen to reduce the chloride to the metal. It is understood that other suitable methods of preparing the catalyst may be employed, but that the amount of platinum or palladium solution utilized is controlled so that the final catalyst contains the concentration of platinum or palladium hereinbefore set forth.

After a period of service, it may be necessary to reactivate the catalyst and this may readily be accomplished by passing air or other oxygencontaining gases therethrough in order to burn carbonaceous deposits from the catalyst. A particularly suitable manner of regenerating the catalyst comprises effecting the regeneration at "a temperature of about 900 to about 950 F., starting with a gas containing about 2% oxygen and gradually increasing the oxygen concentration so that at the end of the regeneration period pure air is being passed over the catalyst. However, it is important that the temperature of regeneration should not exceed 1000 F. as it has been found that these high temperatures tend to impair the catalyst activity. It should be made clear that the use of temperatures above 1000 F. is not harmful'when applied to the cracking component before the platinum or pal- 'ladium is composited therewith, but'that after the components have been composited, the final composite should not be subjected to temperatures above 1000 F. either during regeneration or during preparation of the catalyst.

The platinum and palladium-containingcatalysts may be adversely affected by sulfur and, in another embodiment of the invention, straight run gasoline containing sulfur compounds may be subjected to desulfurization in any suitable manner and the desulfurized gasoline may then be subjected to reforming treatment-in the manner hereinbefore set forth. Anysuitable desulfilllZil'ig catalyst may be employed such as the oxides and/or sulfides of nickel, molybdenum, chromium, etc., or various clays and synthetic silica-alumina composites, etc. A particularly suitable catalyst for use in the desulfurization step of the combination process comprises silicaalumina-nickel which is preferably employed at .a temperature of from about 400 to about 750 F. and at a superatmospheric pressure of from about 50 to about 1000 pounds per square inch.

The process of the present invention may be effected in any suitable equipment. A particularly suitable process comprises the well known fixed bedvsystem in which the catalyst is disposed ,in a reaction zone and the gasoline is passed therethrough at the proper conditions of operation in either upward or downward flow. The products are fractionated to separate excess hydrogen and to recover the desired gasoline fraction. As hereinbefore set forth the hydrogen may be recycled for further use in the process. ;Other suitable units in which the process may be effected include the fluidized type process in which the hydrocarbon and catalystare main- ;tained in a state ofturbulence under hindered settling conditions in the reaction zone, the compact moving bed type process in which the catalyst and hydrocarbon are passed either'concur- .rently or countercurrently to each other, and the suspensoid type operation in which the catalyst is carried as a slurry in th hydrocarbon oil into the reaction zone.

1 The following examples are introduced to fur- 7 their .='illustrate the novelty :and utility ".Of 1 the present. inventiongbut not with the. intention o unduly limiting the same.

' EXAMPLE I .';A. Mid-Continent naphtha'having the characteristics shown in the following table was subjected to reforming in the presence of different catalysts comprising silica alumina zirconia composited with various percentages of platinum.

The silica-alumina-zi-rconia component was prepared by adding muriatic-acid to commercial .water glass in proportions to precipitate silica hydrogel. Th silicahydrogel was washed with acidulated water to remove sodium ions and subsequently submerged in a solution of aluminum chloride and zirooniumoxychloride, after which ammonium hydroxide was added to precipitate alumina. The silica-alumina-zirconia composite was partially dried, formed into pills in a pelleting machine,-a-nd then calcined. Solutions of chloroplatinic acid of the desired concentrations were added to different samples of the silica-alumina-zirconia composite and subsequently the impregnated composite was treated with:a-.hydrogen-containing gas at a temperature-increasing from about 295 F. to about 573 F. in order to reducev the platinic chloride to platinum.

The reforming'operation'was effected at a temperature of about 695-F., apressure of 50 pounds per, square inch, an hourly liquid space velocity of ;.5sand a hydrogen to, hydrocarbon, ratio of 2.7 1. The results of. these runs areshown in the following table.

'Table, 1

Run No Charge 1 2 I 3 4 5 Platinum; grams per 100 1 ,-cc. of final catalyst 0.35 0.7 1.0 1.5 2.l Liquid recovery, percent by volume 93.2 91.9 93.4 92.8 93.2 Octane Nos;

Motor method, clear 32.7 6&3 64.3 66.3 66.1 66.3 Motor method 3 cc.

TE 01.3 77.7 79.0 79.1 80.2 80.0 5% boiling point by Engler distillation 257 214 208 208 192 202 Hydrogen produced, eu-

hic ft. per barrel of charge 630 801 802 783 897 It will be noted that the octane number of the naphtha was increased from 32.7 to above 64 clear and from 61.3 to above 77 upon the additions of Sec. of tetraethyl lead. It will also be noted that selective hydrocrackingoccurs. as is evidenced by lowering of the 5% boiling point. The

5% boiling point has been selected asa' criterion because it is more reliable than th initial boil- "ing point.

EXAMPLE II "The .Mid Continentnaphtha used in Example Iewas subjected to reforming in the presence .of catalysts containing varying percentages of platinum and composited with different cracking components. "The reforming was effected at a temperature of about 775'F., a pressure of 200 :pounds per square inch; an hourly liquid space velocity of 0.5 and-a hydrogen to hydrocarbon --ratio of2.7":l.

.1The silica-aluminazirconia component was prepared in thepmanner described in Example I. The silica-aluminacomponent was prepared by .adding hydrochloric acidto-commercial water glass in proportions to precipitate silica hydro- ,gel, the silica hydrogel being formed, into spheres byvdistxhargingthe mixtureof water glass-and acid into an oil bath in the manner hereinbefore set forth. The silica spheres were washed with acidulated water to remove sodium ions and the spheres were then submerged in a bathof aluminium chloride, after which ammonium hydroxide was added to precipitate alumina. The silica-alumina composite was then dried at a temperature of about 250 F. for ten hours and then calcined at a temperature of 932 F. for about 1 hours.

Solutions of chloroplatinic acid of the desired concentrations were added to difierent samples of the crackin components and the final catalysts were prepared in the manner described in Example I. The results of these runs are indicated in the following table.

1 Sillca-alumina-zirconia. 1 Silica-alumina.

It will be noted that the platinum-silica-alumina-zirconia catalyst containing less than 2 grams of platinum per 100 cc. of final catalyst (Run 6) produced only about 8% non-condensable paraifins, whereas the corresponding catalyst containing over 2 grams of platinum per 100 cc. (Run 7) produced about 18% non-condensible paraiims. It likewise will be noted that with the platinum-silica-alumina catalysts, the percentage of. non-condensible parafiins increases from 2% to about 5% when the platinum concentration is increased from less than 2 grams (Run 8) to more than 2 grams per 100 cc. (Run 9). The increased cracking and resultant carbon formation and gas production are undesirable because of the carbon depositing on and therefore oleactivating the catalyst, and because hydrogen is consumed in saturating the fragments formed by cracking and also because there is a loss of valuable gasoline components to less valuable gases.

In all-cases it will be noted that the yields of liquid product decreases and the octane numbers of the gasoline decreases as the platinum concentrationis increased above 2 grams per 100 cc. of final catalyst.

Special attention is called to the fact that, in Run No. 6, a yield of 90.4% by volume of gasoline havinga clear octane number of 82.5 was obtained. Special attention also is called to Run 8, in which there was produced 97.4% of gasoline having a clear octane number of 77.4 and of 86.2 with 3 cc. of T. E. L. These results are better than heretofore obtained in any reforming process. It will be recalled that most reforming processesare directed to obtaining an yield of an 80 octane number product. It is thus readily seen that the process of the present invention produces greatly improved results.

EYANLPLE III As hereinbefore set forth, the component composited with the platinum or palladium must have cracking activity. This is illustrated in the following table which shows the results of treatmg a Mid-Continent naphtha at a temperature of about 693 F., a pressure of 50 pounds per square inch, an hourly liquid space velocity of 0.5 and a hydrogen to hydrocarbon ratio of 25:1. The Mid-Continent naphtha had an octane number of 40 clear and of 65.6 with 3 cc. of tetraethyl lead by the motor method.

10 500 to about 1000 F., a pressure from atmospheric to about 1000 pounds per square inch and an hourly liquid space velocity of from 0.1 to about 5 in the presence of from about 0.1 to about mols of hydrogen per mol of hydrocarbon, with a catalyst prepared by compositing from about 0.01% to about 2% by weight of final Table 3 Run N0 11 12 13 14 l5 l6 Catalyst carrier Silica-alumina Silica-alumina- Silica-zirconia. Silicamag'nesia Silica. Alumina.

zirconia. Liquid yield, volume percent of 91.5 92.8 92.4 92.2 94.3.... 97.3.

charge. Octane Nos.:

Motor-method clear 71.2............ 66.1 65.3 62.6 58.0. 51.5. Motormethod+ 3 cc.TEL- 81.8 80.2 79.4 75.8 74.2.-. 71.6.

It will be noted that platinum catalysts composited with cracking components (Runs 11 to 14) produced gasolines of clear octane number above 60, whereas the use of inert catalysts carriers (Runs 15 and 16) yielded gasolines of clear octane numbers below 60.

We claim as our invention:

1. A process for reforming a gasoline fraction which comprises subjecting said fraction to contact at reforming conditions with a catalyst comprising alumina, boron oxide and from about 0.01% to about 2% by weight of a metal selected from the group consisting of platinum and palladium.

2. A process for reforming a gasoline fraction which comprises subjecting said fraction to contact at reforming conditions with a catalyst prepared by compositing from about 0.01% to about 2% by weight of platinum with a cracking component comprising alumina and boron oxide.

3. A process for reforming a gasoline fraction which comprises subjecting said fraction to contact at reforming conditions with a catalyst prepared by compositing from about 0.01% to about 2% by weight of palladium with a dry cracking component comprising alumina and boron oxide.

4. A process for reforming a saturated gasoline fraction which comprises subjecting said fraction to contact at a temperature within the range of from about 500 to about 1000 F., a pressure of from atmospheric to about 1000 pounds per square inch and an hourly liquid space velocity of from about 0.1 to about 5 in the presence of from about 0.1 to about 10 mols of hydrogen per mol of hydrocarbon, with a catalyst prepared by drying a composite of alumina and boron oxide at a temperature of at least about 350 F. and incorporating into the dried composite a metal from the group consisting of platinum and palladium in an amount of from about 0.01% to about 2% by weight of the final catalyst.

5. A process for reforming .a gasoline fraction which comprises subjecting said fraction to contact at reforming conditions with a catalyst consisting essentially of a cracking component and a metal of the group consisting of platinum and palladium, said cracking component comprising alumina and boron oxide and said metal being present in an amount of from 0.01% to about 2% by weight of the final catalyst.

6. A process for reforming a straight run gasoline fraction which comprises subjecting said fraction to contact at a temperature of from catalyst of platinum with a dry alumina-boron oxide cracking catalyst.

7. The process of claim 6 further characterized in that said boron oxide is in an amount of from about 1% to about 15% by weight of said alumina.

8. The process which comprises subjecting a sulfur containing fraction to a desulfurization treatment and then subjecting the desulfurized gasoline fraction to reforming in the presence of a platinum-alumina-boron oxide catalyst containing from about 0.01% to about 2% by weight of platinum, said catalyst having been prepared by compositing the platinum with alumina and boron oxide.

9. A method of preparing a catalyst which comprises drying a composite comprising alumina and boron oxide at a temperature of at least 350 F. and incorporating into the dried composite a metal from the group consisting of platinum and palladium in an amount of from about 0.01% to. about 2% by weight of final catalyst.

10. A method of preparing a catalyst which comprises drying a composite of alumina and boron oxide at a temperature of at least 350 F. and incorporating into the dried composite platinum in an amount of from about 0.01% to about 2% by weight of final catalyst.

11. The process of claim 10 further characterized in that said boron oxide is present in an amount of from about 1% to about 15% by weight of said alumina.

12. A catalyst comprising alumina, boron oxide and a metal from the group consisting of platinum and palladium in an amount of from about 0.01% to about 2% by weight of final catalyst. 13. A catalyst comprising alumina, boron oxide in an amount of from about 1% to about 15% by weight of said alumina, and platinum in an amount of from about 0.01% to about 2% by weight of said catalyst.

VLADIMIR HAENSEL. CURTIS F. GERALD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,338,709 Sulzberger May 4, 1920 2,407,918 Burgin Sept. 17, 1946 2,422,884 Burgin June 24, 1947 2,478,916 Haensel et a1. Aug. 16, 1949

Claims (1)

1. A PROCESS FOR REFORMING A GASOLINE FRACTION WHICH COMPRISES SUBJECTING SAID FRACTION TO CONTACT AT REFORMING CONDITIONS WITH A CATALYST COMPRISING ALUMINA, BORON OXIDE AND FROM ABOUT 0.01% TO ABOUT 2% BY WEIGHT OF A METAL SELECTED FROM THE GROUP CONSISTING OF PLATINUM AND PALLADIUM.