4721 4725.output

* GB785128 (A)

Description: GB785128 (A) ? 1957-10-23

Improvements relating to clamping couplings for tubular scaffolding

Description of GB785128 (A)

, c" , '7c c " 7 F: PATENT SPECIICATION Inventor:-PETER BARTON. 785; 128 :785,128 Date of filing Complete Specification: March 5, 1956. Application Date: March 26, 1955 N Yo 8889 l 55. Complete Specification Published: Oct 23, 1967. Index at Acceptance:-Class 20 ( 2), 53. International Classification - E 04 g. COMPLETE SPECIFICATION. Improvements relating to Clamping Couplings for Tubular Scaffolding. We, B C BARTON & SON LIMITED, of Hainge Road, Tividale, Tipton, in the County of Stafford, a British Company, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement:- This invention relates to clamping couplings for tubular scaffolding and has for its object to provide a coupling suitable for clamping in position horizontal scaffolding tubes bearing relatively small loads, which coupling requires the manipulation of a single screw means only and avoids the necessity of threading the tubes through the coupling. The present invention consists of a clamp for holding two tubes at right angles consisting in a bracket or member having a curved cradle for engaging a first tube by lateral approach thereof, a flanged extension on said bracket for supporting a second tube at right angles to the first tube when -resting on the first tube by lateral approach of the second tube and a screw member carried by the bracket, the nose of which screw member i S adapted to impinge upon the second tube and force it into contact -with the first tube so as to securely locate the tubes at right angles in the bracket. The present invention further consists of a clamping coupling for

tubular scaffolding comprising a substantially G-shaped bracket or member wherein the lower portion of the C bracket is provided with an arcuate elongated flange extending in a horizontal plane at right angles to the plane containing the C bracket and adapted to receive one scaffolding tube, the lower inner periphery of the C bracket is dished in the opposite direction to the arcuate flange and adapted to receive and lend support to the'second scaffolding tube disposed at right angles to the first tube and bearing thereon, and screw means is provided at the upper part of the C bracket -adapted to impinge at an "off centre" position on the surface of the second tube and thereby clamp the second tube in abutment with both the first tube and the periphery of the dished part. In order that the invention may be clearly understood and readily carried into practice reference may be had to the appended explanatory drawings in which:Figure 1 illustrates the clamp in elevation; and Figure 2 is a plan view thereof. In a convenient embodiment of the invention there is provided a substantially Cshaped bracket 'a The normally horizontal lower limb of the C bracket is provided with a cradle or flange a' of arcuate cross section extending horizontally and adapted to receive a scaffolding tube b The lower inner portion of the C bracket a is provided with a flange a 2 inclined to the said C bracket a and extending in the opposite direction to the arcuate flange al, the second flange providing a support for a second scaffolding tube c which tube rests also upon and at right angles to the first tube b. This second flange d may extend upwardly at a' to give strength to the bracket The upper extremity of the C bracket is slit at three positions to provide four segments ad which are pressed outwardly in alternate directions thereby forming a socket which is tapped to receive a bolt d having desirably a thumb screw type head d' The socket a 4 is formed in the bracket to admit of impingement of the nose d 2 of the bolt at an "off centre" position on the surface of the second tube c, (see Figure 1} i e the bolt is directed along a chord of the second tube c outwardly displaced from the vertical diameter thereof The bracket may have strengthening ribs pressed up from the metal along its length. In use the arcuate flange al of the coupling is hooked upon the first scaffolding tube d by lateral approach and the second tube c is then laterally engaged with the bracket a and located in abutment with the periphery of the second or inner flange a 2 and also with the first tube b. The bolt d d' is then tightened to securely clamp the tubes c and d together and positively prevent their lateral separation from the clamping bracket a.

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* GB785129 (A)

Description: GB785129 (A) ? 1957-10-23

Improvements in helical gears


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PATENT SPECIFICATION Date of Application and filing Complete Specification: April 18, 1955. Application made in Italy on March 2, 1955 Complete Specification Published: October 23, 1957 7 (C-li V?, 785,129 No 11111/55 Index at acceptance:-Class 80 ( 1), G 7 C 2. International Classification:-FO 6 h. COMPLETE SPECIFICATION

Improvements in Helical Gears We, PHILLAC S A, of rue de la Corraterie, 13, Geneva, Switzerland, a Swiss Company, do hereby declare the invention, for which we pray that a patent may be granted to us, S and the method by which it is to be performed, to be particularly described in and by the following statement:- Gear pairs of the type with helicoidal teeth, having parallel axes wherein the middle helixes of the teeth of the pinion and of the teeth of the wheels are differently inclined but having equal axial pitches and having their contact always on one side of the plane of the axes, are already known some of which are of a reversible nature whilst others are irreversible, for example Patent No 656,136 and Patent No 656,169. This invention is concerned with a particular construction of the teeth of said wheels at the limit on one side of which the gearing is reversible whilst, on the other side of said limit, the gearing is not reversible. The invention consists of a pair of helical gears as hereinbefore defined operating near the limit between reversibility or irreversibility said limit being determined by selecting tooth parameters so as to cause when a drive from the driven to the driving wheel is attempted the resultant of the force exerted between contacting teeth and of the frictional force due to sliding to pass through the axis of the driving gear. The wheels according to the invention are further characterised in that, in order to realize the limiting condition between reversibility and irreversibility, the variations in the value of said friction force is allowed for in using materials, lubricants and the like, of various types giving various friction coefficients. The accompanying drawing shows, only by way of example, an illustrative embodiment of the gears according to this invention, -45 being a section on a plane perpendicular to the axis of the wheel and that of the pinion. The drawing shows the limit between the conditions of reversibility and irreversibility of the gearing. Referring to the drawing, 0, and 02 are 50 the centres of the pinion and the wheel disposed on parallel axes and having helicoidal teeth The inclinations of the middle helixes of the teeth of the pinion and the teeth of the wheel are different, but they have equal 55 axial pitches 1 and 2 are the relative rolling circles, i e circles about the axes of the gears in rolling contact at point C which would give the same speed ratio; 3-4 and 5-6 are the corresponding profiles of the 60 sections of the teeth of the pinion and the wheel: said profiles make contact at the point 11 and each one is constituted by a curve (which may be cycloidal or involute or of other types) having an

only slightly 65 variable radius of curvature, and are spaced from the point C The contact point 11 is constantly on one side of the plane 0,-02 passing through the axes of the pinion and of the wheel; 7-8 and 9-10 are the root 70 circumference and the top circumference of the teeth of the pinion and of the wheels. The force N perpendicularly exerted at 11 between the contact teeth and passing through the point C has, as well known, a 75 direction that is constant when the corresponding profiles 3-4 and 5-6 are involute and has a variable direction when they are cycloidal or have some other shape The force N presents an inclination (e with 80 respect to the perpendicular drawn from the point C to the line connecting the centres of the wheel and pinion upon which depends the reversibility or irreversibility of the gear pair; as in fact, the force N is compounded 85 with the force T of friction it has produced, owing to the sliding caused between the profiles, to form a resultant R which, as the gear having centre 02 becomes a driving one, will pass through the axis 0, of rotation 90 of the pinion (the limit case shown in the -figure) producing a zero driving moment and therefore producing irreversibility of the gearing. From the aforesaid it is seen that, by means of suitably related tooth parameters, it is possible to arrange that the said rev sultant R passes through the centre 01 so that it will generate a zero driving moment J O and provide an irreversible gearing. This result is affected by the value of the tangential friction force T It is therefore possible to influence the result by means of a convenient choice of the factors influencI 5 ing the value of the force T, such as materials; lubrication and so forth.


* GB785130 (A)

Description: GB785130 (A) ? 1957-10-23

An improved variable pitch pulley


PATENT) S PE CF -C A T PATEN 9 T SPECIFICATIO Nl Date of filing Complete Specification: April 30, 1956. Application Date: April 30, 1955 No 12592/s 55. Complete Specification Published: Oct 23, 1957. Index at Acceptance:-Class 80 ( 2), D 4 A. International Classification:-FO 6 h. COMPLETE SPECIFICATION. An Improved Variable Pitch Pulley. We, EDWARD J SKINNER LIMITED, of Boulton Road, Lode Lane, Solihull, in the County of Warwick, a British Company, and ALAN PHILIP LAWLESS THOMAS, of Marston Hall, Marston Green, near Birmingham, a British Subject do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement: - This invention relates to variable pitch pulleys of the kind comprising two flanges having mutually inclined opposite faces adapted to receive a V belt therebetween one of the flanges being transversable with respect to the other flange to admit of variable separation of the flanges against a compression spring resistant and consequent variation of the pitch circle diameter of the pulley according to the tension present in the belt. The present invention is also applicable to a variable pitch pulley of the aforesaid kind wherein the pulley flanges are transversably mounted on a concentric sleeve securable to a shaft to admit of automatic alignment of the pulley with the belt. The invention has for its object to provide a simple and efficient anti-friction traversable mounting of one pulley flange with respect to the complementary flange or of the pair of flanges with respect to the shaft sleeve. The invention consists of a variable pitch pulley of the kind referred to wherein a sleeve secured to the traverable pulley flange is slidably mounted on a concentric sleeve secured to the complementary pulley flange, a longitudinal groove or grooves being provided in register in the presented faces of the said sleeves to accommodate a plurality of contiguous balls or rollers which lPrice 3 s 6 d l form an anti-friction key between the said sleeves; the invention further consists of the 45 provision of an additional row or rows of

contiguous balls or rollers which serve to form an anti-friction key between registering grooves formed in the periphery of the shaft sleeve and in the bore of the adjacent 50 sleeve. A convenient embodiment of the invention will now be described with reference to the accompanying drawing showing a longitudinal sectional elevation of the pulley 55 As seen in the drawing a sleeve 1 is adapted to be secured to a shaft e g by a set screw la, and a concentric sleeve 2 having an integral pulley flange 2 a at one extremity (hereinafter called the master 60 flange) is traversably mounted on the shaft sleeve 1 A pair of diametrically opposed arcuate grooves lb and 2 b are formed longitudinally and in register in the presented surfaces of the shaft sleeve 1 and the bore 65 of the -master flange sleeve 2 respectively the grooves lb of the shaft sleeve being terminated at a position adjacent the master flange The grooves accommodate a plurality of balls 3 forming an anti-friction key, 70 the balls being retained in contiguity within the grooves by means of a circlip 4 provided on the periphery of the shaft sleeve 1 and a circlip 5 provided in the bore of the master flange sleeve 2 75 A further sleeve 6 with the traversable flange 6 a of the pulley is concentrically located on the master flange sleeve 2 and a pair of axially directed arcuate grooves 6 b and 2 c are formed longitudinally and in 80 register in the bore of the traversable flange sleeve 6 and in the surface of the master flange sleeve 2 respectively The groove 6 b extends along the lengths of the traversable flange sleeve 6 and the groove 2 c in the 85 master flange sleeve is terminated adjacent 1-, 785,130 the traversable flange 6 a A plurality of balls 7 forming an anti-friction key are retained in contiguity in the grooves 6 b and 2 c by the deformation of the end of the groove in the traversable flange sleeve 6 remote from the flange and by means of circlips 8 and 9 provided in the bore of the traverasable flange sleeve 6 and the periphery of the master flange sleeve 2 respectively. The opposite faces of the pulley flanges 2 a and 6 a are inclined in known manner and the traversable flange 6 a is urged towards the master flange 2 a by means of a concentric compression spring 10 interposed I 5 between the traversable flange 6 a and a collar 11 secured to the extremity of the master flange sleeve 2, telescopically associated cylindrical covers 12 a and 12 b being conveniently mounted on the traversable flange 6 a and the collar 11.

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* GB785131 (A)

Description: GB785131 (A) ? 1957-10-23

Improvements in or relating to clutches


PATENT SPECIFICATION Date of filing Complete Specification: Mlay 2,1956. a) Application Date: May 2, 1955 No 12702155. Complete Specification Published: Oct 23, 1957. Index at Acceptance:-Class 80 ( 2), C 1 O( 4 A: 7: 9), Ol D. International Classification:-F 06 d. COMPLETE SPECIFICATION. Improvements in Or relating to Clutches. I, TREVOR EVANS MEREDITH, a British Subject, of 67 Oakfield Road, Shrewsbury, formerly of Bamnford Cottage, South Hill Avenue, Harrow, do hereby-declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to clutches. According to the present invention there is provided a clutch comprising a driving shaft, a first plate carried on the driving shaft to rotate therewith, a first gear slidably mounted on the shaft and having gear teeth that are oblique to the axis of the shaft, a second plate carried by the gear to rotate therewith, the second plate being adjacent the first plate to co-operate therewith, a second gear meshing with the first gear and mounted on a driven shaft, and means for locking the first gear to prevent this gear from rotating with the driving shaft, the arrangement being such that when the locking means is inoperative and the driving shaft is rotated in the appropriate direction, the first gear tends to rotate with the driving shaft and because of the engagement of the two gears and the oblique nature of the teeth, is moved towards the first plate until the second plate frictionally co-operates with the first plate whereby -the clutch

becomes engaged and -the -driven shaft is rotated, the arrangement-being further such that the clutch is disengaged by operating the locking means to prevent the first gear from rotating with the driving shaft. For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made-to the accompanying drawing, in which Figure 1 is a diagrammatic sectional view lPrice 3 s 6 d l of a clutch, the section being taken on I-I of Figure 2; and Figure 2 is an end view of the clutch of Figure 1. The clutch has a driving shaft 1 connected to be driven by a motor 2, there being bearings 3, 4 near the ends of the shaft 1 to support same A circular plate 5 is keyed to the driving shaft 1 co-axially therewith, and has a friction plate 6 on one surface thereof A movable member 7 is mounted as a sliding fit on the driving shaft 1 co-axially with the circular plate 5 The movable member 7 consists of a worm gear 8 with a right-hand thread and bosses 9, 10 one at each end of the worm gear 8 A circular plate 11 adjacent the friction plate 6 is formed on the outer end of the boss 10 and a circular flange 12 with peripheral indentations 13 therein, is formed on the outer end of the boss 9 A collar 14 is provided on the driving shaft 1 at a location near the circular flange 12 for limiting the extent of movement of the movable member 7 along the driving shaft 1 in the direction away from the plate 5. A worm wheel 15 fixed to a driven shaft 16 is arranged to be driven by the worm gear 8 and is centrally positioned with respect to the length of the worm gear 8. A leverl 17 is laterally disposed with respect to the flange 12 and is pivoted on a fixed member 18 The end 17 A of the lever 17 has a latch 19 thereon for engaging in the peripheral indentations 13 in the flange 12 The opposite end 17 B of the lever 17 -:-has an armature 20 that co-operates with a solenoid 21 connected in series with a battery 22 and a switch 23 A spring 24 connected between the lever 17 and the member 18 urges the latch 19 into engagement with one of the indentations 13. In the employment of the clutch described ) R ',) ' F) 1 ' ,f f 75 j z P) 1 d C/ L, , L'', e) ' "' -785,131 above, the latch 19 of the lever 17 is disengaged from the peripheral indentations 13 of the flange 12 by closure of the switch 23 to energise the solenoid 21 The armature 20 moves downwardly until the lever 17 encounters a stop 25, and hence the latch 19 moves upwardly and away from the flange 12 When there is a load on the driven shaft 16, and the driving shaft 1 is rotated, the friction between the driving shaft 1 and the bore of the movable member 7 is sufficient to cause the movable member 7 to begin to rotate and because of the engagement between the worm gear 8 and the

worm wheel 15 the movable member 7 is caused to move along the driving shaft I. It will be appreciated that the direction of rotation of the driving shaft 1 and the hand of the worm gear 8 determines the direction of motion of the movable member 7 along the driving shaft 1 The direction of rotation of the motor 2 is selected so that the movable member 7 is caused to move towards the plate 5. When the plate 11 engages the friction plate 6, a frictional force in addition to that arising between the surfaces of the bore of the member 7 and the driving shaft 1, will be exerted, tending to rotate the worm gear 8 The effect is cumulative and the greater the load on the worm wheel 15, the greaterwill be the end thrust of the plate 11 against the friction plate 6 Disengagement of the clutch is effected by opening the switch 23 to de-energise the solenoid 21 The spring 24 then tilts the lever 17 so that the latch 19 engages in one of the peripheral indentations 13 in the'flange 12 The engagement of the latch: 19 in the indentation 13 arrests the movable member 7 The worm wheel 15 will tend to continue to rotate due to inertia and this rotation of the worm wheel 15 will tend to move the worm gear 8 away from the frictional plate 6 and towards the collar 14. In a modified form of the apparatus described above the flange 12 is dispensed with and instead the plate 11 is enlarged, the indentations 13 with which the latch 19 cooperates being formed in the periphery of the plate 11.


* GB785132 (A)

Description: GB785132 (A) ? 1957-10-23

Improvements in platinum-containing catalysts


COMPLETE SPECIFICATION Improvements in Platinum-containing Catalysts We, THE ATLANTIC REFINING COMPANY, a corporation organised under the laws of the State of Pennsylvania, United States of America, of 260 South Broad Street, Philadelphia, Pennsylvania, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to platinum-containing catalysts and to their method of -preparation and use, and more particularly to platinum-containing catalysts having a high stability prepared from a specific complex compound of platinum and to the use of such catalysts in reforming processes. Platinum-containing catalysts have long been used industrially for a variety of processes and in recent years have gained even more widespread use, particularly in the petroleum industry in processes for reforming gasoline fractions, dehydrogenation of selected cycloparaffins to produce pure aromatics, isomerization of paraffins, isomerization of alkyl aromatics and similar processes. It is well-known that the term "reforming" as used in the petroleum industry refers to the treatment of petroleum hydrocarbon fractions boiling in the gasoline range to improve the anti-knock characteristics or octane value thereof, and most frequently the term is applied to the treatment of straight run and thermally cracked gasoline fractions. Straight run and thermally cracked gasoline fractions are composed of straight chain, slightly branched chain, cyclic paraffins and olefins, all of which have relatively low octane values, together with only minor amounts of aromatics. In order to increase the octane value of the non-aromatic compounds in these low octane fractions, it is desirable to isomerize the straight chain and slightly branched chain hydrocarbons to highly branched chain compounds, and to isomerize the cyclic saturated compounds (naphthenes) to six carbon ring structures which can be dehydrogenated to the corresponding aromatics, the dehydrogenation reaction being especially important since the aromatics so produced contribute markedly to the over-all octane improvement. Another desired reaction is the conversion of paraffins to aromatics by dehydrocyclization. Finally, and of considerable importance, there is the selective

cracking of the high molecular weight hydrocarbons to produce high yields of lower molecular weight normally liquid products without the formation of large amounts of gas and coke. Although many compositions have been proposed as being useful in promoting one or more of the above reactions, only certain platinum impregnated acidic metal oxide component catalysts are known to be capable of successfully promoting all of the desired reactions in a ratio which will give the greatest octane improvement with the lowest loss in yield. One example of such a catalyst contains silica and alumina as the acidic metal oxide component. Other acidic metal oxide components which may be impregnated with platinum for use in this invention include: alumina, silica-zirconia, silica- alumina- zirconia, silica- magnesia, silica-alumina-magnesia, silica-thoria, silicaalumina thoria and alumina-thoria. These metal oxide components are characterized by having exchangeable hydrogen ions in their structure. Their preparation and properties have been published widely both in patents and in technical literature, therefore, for purposes of brevity, this information will not be reiterated here. Likewise, the proportions of the various individual oxides which can be combined to produce the acidic metal oxide component may vary over relatively wide ranges as has been set forth in the prior patent and literature art. Of particular importance to catalytic reforming are those catalysts described in Patent No. 686,641. According to the former patent the acidic metal oxide component, prior to platinum impregnation, is treated in a particular manner to lower its surface area so as to permit thereby an increase in the temperature range at which a maximum - amount of paraffin isomerization is obtained with the finished catalyst, and so that at the elevated temperatures required for aromatic formation there will not be a loss in paraffin isomerization yield. In other words, the proper ratio or balance between the various reforming reactions is obtained by adjusting the surface area of the acidic metal oxide component to between 10 and 65 square meters per gram. It is necessary when using these catalyst in a reforming operation, however, to have present rather large amounts of hydrogen, which functions to maintain the catalyst in a clean condition, free of coke and carbonaceous deposits which would substantially deactivate the catalyst if allowed to accumulate. Since there is a net production of hydrogen in the over-all reforming reaction, there is no serious problem with respect to hydrogen supply. To make- the hydrogen effective, superatmospheric pressures must be used or, in other words, the hydrogen partial pressure must - exceed one atmosphere. The dehydrogenation reaction is one of the most rapid of the reforming

reactions and, therefore, under most operating conditions, equilibrium can be readily reached between the naphthenes and the aromatics. Since, however, the volume of the products exceeds the volume of the reactants, the reaction- is of course affected by pressure inthe reverse direction-that is, the formation of aromatics is decreased as the pressure is raised at a constant reaction temperature. In addition, it is well-known that at a constant pressure, as the reaction temperature is increased, the equilibrium shifts in the direction of higher aromatic production. It follows, therefore, that since it is highly desirable to have the equilibrium as far as possible in the direction of maximum production of aromatics and, since superatmospheric pressures must be used, higher temperatures must also be employed. To summarize the foregoing: (a) hydrogen at superatmospheric pressures is necessary to maintain the reforming catalyst in a clean condition, (b) - dehydrogenation of naphthenes to aromatics produces hydrogen and in addition furnishes an important increment of octane improvement, -(c) equilibrium considerations require the use of elevated temperatures to produce the maxi mum quantities of aromatics and hydrogen at the superatmospheric pressures, and, (d) isomerization reactions must be promoted to a maximum extent within the same range of conditions where maximum aromatic for mation is realized. When all four of these requirements are met simultaneously in a reforming process, that is, when all of the desired reactions are in proper ratio one to the other, there results the optimum yield octane relationship for the process. Although, as has been noted, several cata lysts have been described in the prior art wherein an acidic metal oxide component has been impregnated with platinum, these catalysts have all been subject to a common disadvantage, namely, that their activity declines during use and although in some cases this decline is relatively slow and re generations with air can be used to extend the life of the catalysts, nevertheless, this decline is sufficient to require complete re placement of the catalysts after a period of use.. In the case of catalytic reforming, the

decline in activity is manifested by gradual decline in ability to promote the dehydro genation reaction, i.e, the conversion of naphthenes to aromatics, and in the ability of the catalyst to promote the isomerization reactions at the temperature levels required for optimum dehydrogenation. This change in activity of the catalyst will result finally in failure to maintain the desired octane level in the product. The measure of a cata lyst's resistance to this decline in activity will hereinafter be referred to as its stability. Since the aforementioned catalysts suffered universally from the same disadvantage, namely, lack of stability, it is reasonable to assume that this characteristic was due to either an inherent property of such catalysts or to a common defect introduced in their preparation. Since preparation of catalysts is often extremely important to their final characteristics, the various methods of pre paration which have been described were studied. Several methods of impregnating various carriers, including the acidic metal--oxide components, with platinum have been described in the prior art, the most com monly used method being to contact the carrier material with an aqueous solution of a compound of the metal, such as chloro platinic acid, ammonium platinum chloride, trimethylbenzyl a m m o n i u m platinum chloride, platinous tetramminochIoride and dinitro diammino platinum. In the case of impregnation with com -pounds of platinum wherein the platinum is in the anionic portion of the compound, for example, chloroplatinic acid, it is now believed that the impregnation is merely a mechanicaI deposition. In the case of im pregnation with those compounds wherein the platinum is in the cationic portion of the compound, use is made of that fact that the acidic metal oxide component has base exchange properties, i.e., it contains replaceable positive hydrogen ions. It is necessary, however, in order to make use

of this property, that the impregnating solution be kept strongly alkaline, preferably above a pH of 9. For example, if a platinous tetramminochloride solution is used, the pH is raised to about 11 by the addition of about eight mols. of ammonium hydroxide per mol. of -the platinum compound, under which conditions the platinum-containing cation replaces the hydrogen ion in the structure of the metal oxide component or carrier. In all of the prior art preparations the impregnated acidic metal oxide component was either treated with hydrogen at elevated temperatures or with air at elevated temperatures to convert the platinum to the metallic state. These treatments were referred to as reduction with hydrogen or calcination with air. In some instances calcination is referred to as decomposition. It was noted further that in all of the prior art preparations such ions as halogens, nitrates, sulfides and the like, were brought into contact with the acidic metal oxide component during the platinum impregnation step and that during the subsequent high temperature treatment to produce metallic platinum, whether by hydrogen or air, these residual ions were removed although obviously before their complete removal they were in contact with the impregnated material at temperatures conducive to reactions which could result in lowering the stability of the final catalyst. It has now been found that by impregnating the acidic metal oxide component with a specific complex compound, it is possible to avoid the presence of the abovementioned dleterious ions and produce a catalyst having a stability markedly greater than that of catalysts prepared according to the prior art methods. It is therefore an object of this invention to provide platinum impregnated acidic metal oxide catalysts of superior stability. It is a further object of this invention to provide a method of manufacturing platinum impregnated acidic metal oxide catalysts of superior stability. It is an additional object of this invention to provide a method of preparing platinumcontaining catalysts by impregnating an acidic metal oxide component with a specific complex compound of platinum. It is an important object of this invention to prepare platinum-containing catalysts by impregnating the reduced surface area components of Patent No. 686,641 with a specific complex compound of platinum and utilize such catalysts in catalytic reforming processes. It is another object of this invention to prepare platinum-containing catalysts by impregnating an acidic metal oxide component with a platinum compound free of ions which reduce the stability of the finished -catalyst. In accordance with the invention there is provided a method of

preparing a platinumcontaining catalyst, which comprises impregnating an acidic metal oxide component with an aqueous solution of platinous -tetramminohydroxide, drying the impregnated acidic metal oxide component, and converting the platinous tetraminnohydroxide impregnated on the acidic metal oxide component to metallic platinum. Thus in carrying out the present invention, one of the abovementioned acidic metal oxide components may be contacted with a small excess of an aqueous solution of platinous tetramminohydroxide. This solution and metal oxide component mixture is then heated to an elevated temperature, generally to about the boiling point of the solution, and is held at this temperature for a period of time which may range from about four hours to twenty-four hours. Although, the base exchange reaction between the platinous tetramminohydroxide solution and the acidic metal oxide base is extremely rapid and is practically complete when the oxide has become wetted by the solution, it has been found that by "aging "- the- carrier in the impregnating solution at an elevated temperature the - cationic platinum apparently "migrates" to the most active portions of the acidic metal oxide component, -whereby a more active and stable finished catalyst is produced. Generally at temperatures of 210 F. to 212 F. the major portion of the aging effect has occurred at the end of 3 to 4 hours; however, in a few cases some additional improvement has been noted when the heating has been continued up to 18 to 24 hours. It has been noted also that if the temperature is increased, as by heating under super-atmospheric pressures, the aging time can be shortened. If necessary distilled or de-ionized water should be added to the solution during the aging step to replace any water lost by evaporation. After the aging step, the spent solution is drained from the impregnated metal oxide component, then the impregnated component preferably is dried to remove excess moisture, following which step the dried impregnated carrier is subjected to the known methods for decomposing or reducing the platinum complex to produce metallic platinum on the metal oxide component, such -as calcination with air or reduction with hydrogen at elevated temperatures. The compound, platinous tetrammino hydroxide, is believed to have the molecular formula: [Pt(NH3)J (OH)2. It produces an aqueous solution having a pH generally of about 12 or above. Thus, this solution automatically has the high pH required for base exchange. The cationic platinum rapidly replaces the hydrogen ions in the metal oxide component and the hydrogen ions neutralize the hydroxide ions of the solution It has been observed that during the impregnation the pH of the solution drops very rapidly. In the case of silica-alumina as the metal oxide component this value will be about 4, which is the characteristic pH produced in water which is in contact with the

silica-alumina. It is believed that the high stability of the catalysts prepared according to this invention results from the fact that no undesirable ions such as halides, sulfides, nitrates, or the like are brought into contact with the carrier, which residual ions according to prior art preparation methods were removed in the decomposition step by calcination with air or reduction with hydrogen. This decomposition or reduction step in the present invention is merely for the purpose -of producing metallic platinum on the carrier. The present invention offers an important additional advantage. Since there are no undesirable ions present in the original impregnating solution, and since the only byproduct of the impregnation is water, the solution remaining after the impregnation, after fortification with additional platinous tetramminohydroxide, can be used for treating a second batch of acidic metal oxide component. In the case of the prior art impregnation methods, where undesirable ions remained in the spent impregnating solution, it was - necessary to first recover the platinum from the spent impregnating solution before it could be used for impregnating a second batch of acidic metal oxide component. It has been found desirable to use a slight excess of impregnating solution over that required to wet the acidic metal oxide component. - In the case where the metal oxide component is in pelleted or granular form, it has been found that about 1.2 cc. of impregnating solution per gram of the metal oxide provides sufficient excess. The concentration of the platinous tetramminohydroxide in the solution can be adjusted according to the desired amount of platinum to be placed on the metal oxide component It has been found experimentally that for the acidic metal oxide components above mentioned something in excess of 95 per cent of the platinum content of the solution is exchanged onto the base. For example, if it is desired to produce a finished catalyst containing about 0.45 per cent platinum, an approximately 0.02 molar solution of the platinous tetramminohydroxide should be used with a ratio of 1.2 cc. of solution per gram of metal oxide component. In the preparation of platinum-containing reforming catalysts, the amount of platinum which is desired on the acid metal oxide component generally ranges from 0.1 to 2.5 per cent. The method of the present inven tion, however, is obviously not limited to those percentages, since higher or lower percentages can be deposited on the acidic metal oxide merely by adjusting the con

centration of the solution of platinous tetramminohydroxide. The platinum ordi narily constitutes a minor portion generally less than 20 per cent, and the acidic metal oxide a major portion of the finished catalyst. As hereinbefore mentioned after the acidic metal oxide component has been impregnated and aged, it is preferably dried at conventional temperatures, such as those ranging between about 212 F. and 325 F., using conventional methods such as tumble drying or drying with hot air or nitrogen, or similar inert gas. Having removed the excess moisture from the impregnated metal oxide component, the next step likewise is conventional for decomposing or reducing the platinum complex to produce metallic platinum on the metal oxide component For example, this step may be air calcina tion at temperatures ranging between about 600 F. and 1000 F., but it is preferably carried out between about 650 F. and 750 F. When it is desired to reduce the platinum to the metallic state with hydrogen, temperatures ranging between about 450 F. and 1000 F. may be used. The invention will be further illustrated in Examples I1I-V which follow and the drawings. These are given for purposes of illustration only and the invention in its broader aspects is not to be limited thereto. In the following examples a number of catalysts were prepared both according to prior art methods, and according to the method of the present invention. In order to show the superior stability of the catalysts of the present invention, all the catalysts were tested according to a standard reforming test procedure in the laboratory since it was obviously impractical to test every experimental catalyst in a full scale or commercial reforming operation. In the laboratory reforming stability test a 75 cc. portion ofthe -catalyst is placed in a fixed bed in the form of discrete pellets or granules (8-12 mesh, U.S. standard) and an East Texas distillate having the following properties: ASTM Distillation: Overpoint 180 F.

50 Per ~Cent .. 250" F. 95 Per Cent .. 330 F. Endpoint .. 365 F. Clear Octane Number (ASTM Method D908-51) 55 API Gravity at 60 F. 56.5 is passed thereover under the following conditions: Inlet temperature to the catalyst bed and outlet temperature from the catalyst bed is maintained at 875 F. for 24 hours, and then raised to 940 F. for the remainder of the test; hourly liquid space velocity of 3; pressure of 500 pounds per square inch; hydrogen to hydrocarbon mol. ratio is 10 to 1. Samples of product are taken at regular time intervals during the run, and their octane numbers determined. The difference in octane number of the product after the catalysts have been on stream for 72 hours and after 200 hours at a constant average catalyst bed temperature is utilized as a part of the measure of the catalyst stability as will be shown hereinafter. The reactor consisted of a metal tube surrounded by heaters to maintain other mal conditions. A thermocouple well was placed at the centre of the reactor so that the temperature of the catalyst bed could be determined throughout its length. It is a characteristic of the reforming process using a fixed bed reactor with a platinum on metal oxide component type catalyst that at a point near the top of the catalyst bed the temperature of the catalyst will be at a minimum, which temperature is somewhat lower than either the inlet or outlet temp era- tures heretofore mentioned. The explanation for this minimum in the catalyst bed temperature is relatively simple. As has been noted, one of the most important and also most rapid reactions in catalytic reforming is the dehydrogenation reaction, i.e., the conversion of naphthenes to aromatics. This reaction is highly endothermic, that is, it utilizes rather large amounts of heat. Inasmuch as it is a reaction that proceeds rapidly, it reaches its maximum rate at a point near the top of the catalyst bed and, under the specified experimental conditions, it removes heat faster than it can be sup- plied with the result there will be a minimum in the temperature "profile" of the catalyst bed at the point where the dehydrogenation reaction is at its maximum. With a catalyst of high stability, since the heat input and other conditions are constant, this "minimum bed temperature," as it will be referred to hereinafter, will remain at nearly a constant value. Obviously, if the catalyst's ability to promote the dehydrogenation reaction declines during its life, less dehydrogenation will occur and therefore less heat will be utilized, with the result the minimum bed temperature will rise. Consequently, the increase in minimum bed temperature gives very

important information as to the stability of the catalyst under test. As noted hereinbefore the difference in octane value of the product after the catalyst has been on stream for 72 hours and after 200 hours is noted. This difference, while of obvious value in judging stability, might possibly be misleading if used as the sole criterion for stability. It might be misleading for example, if a catalyst started out with good over-all reforming characteristics, but later lost its ability to dehydrogenate while greatly increasing the hydrocracking reaction. The hydrocracking reaction will of course raise octane values, but at the expense of producing large amounts of low molecular weight compounds not useful in gasoline. Thus, in the above example, while the octane decrease might be small indicating a relatively stable catalyst, actually such a catalyst could have relatively poor stability. Therefore, by using a combination of minimum bed temperature change and octane value change over the period of test, a much more reliable and accurate measure of catalyst stability for reforming can be obtained. The above described test gives an accelerated decrease in stability because of the extremely severe temperature levels used. In commercial plant operation, of course, much lower severities are used hence the decrease in octane number with time and decrease in the dehydrogenation reaction with time are considerably more gradual. Thus, although in the laboratory test octane number declines of several units may be experienced in a 128 hour period, such declines require weeks or months in actual commercial operation. The correlation of the accelerated laboratory stability test has been found to be very good, however, with regular plant runs. Although the changes noted in the short time period of the labortary test require much longer times to be observable in plant scale operation, small differences between catalysts as measured in the laboratory are important since these differences extrapolated to the long periods of time desired in plant operation will become very large and represent a difference between a satisfatory and nonsatisfactory operation. A method has been devised which not only makes use of the difference found between actual catalysts tested in the laboratory and expresses such differences in terms of relative stabilities, but which also compares the relative stabilities of actual catalysts with a theoretical completely stable catalyst as a standard. If a catalyst were completely stable it would, of course, show neither an octane number decrease nor a minimum bed temperature increase when tested in the abovedescribed laboratory reforming stability test. For purposes of the comparison, this standard or "perfect" catalyst is assigned a total -relative stability number of 100. Actual catalysts

obviously will have total relative stability numbers less than the theoretical value of 100, since they will show a minimum bed temperature increase and an octane number decreases It is to be noted, however, that both factors contribute to the total stability of the catalyst accordingly, a partial relative stability number is given to each, the sum of such partial relative stability numbers being the total relative stability number Since, as has he n pointed out, dehydrogenation reaction stability is of primary importance, the relative contribution of dehydrogenation reaction stability (measured by minimum bed temperature increase) to the total relative stability is greater than the contribution of the octane number stability to the total relative stability. In order to properly weigh these relative contributions, a value of 60 was selected for the partial relative- stability number of the dehydrogenation - reaction stability contribution and a value of 40 for the partial relative stability number- of the octane number in the case of the standard catalyst. These partial relative stability numbers-for actual catalysts are in the same ratio, but obviously less than the standard values of 60 and 40, respectively. It has been found that a commercially acceptable catalyst when tested by the laboratory method showed a minimum bed temperature increase between the 72nd hour and 200th hour of 6" F., and an octane number decline during the same time period of -3. This present commercially acceptable catalyst was assigned a total relative stability number of 50. From these data the plots in the accompanying drawings were constructed. In the drawings, Figure 1 is a plot of the partial relative stability number for the dehydrogenation reaction- contribution (minimum bed temperature increase) versus minimum bed temperature increase as determined in the laboratory reforming stability test. Figure 2 is a plot of the partial relative stability number - for the octane number contribution versus-the clear octane number decrease as determined in the labortary reforming stability test. Referring now to Figure 1 of the drawings where the partial relative stability number for the dehydrogenation reaction stability contribution is plotted along the ordinate and the minimum bed temperature increase iS plotted along the abscissa, the abovementioned standard catalyst, designated "Catalyst S," is located, of course, at 60 on the ordinate of the plot, as shown. The abovementioned commercially acceptable e talystX designated "Catalyst A,"which was prepared - by impregnating a reduced surface are area silica-alumina component prepared as described above was contacted with an 0.026 molar aqueous chloroplatinic acid solution, 1.2 cc. of solution being

used per gram of pellets. This solution was allowed to remain in contact with the silica-alumina for about 24 hours at approximately 210 F. to 212 F. The impregnated pellets of silica-alumina were then dried in a stream of nitrogen at a temperature - somewhat above 212 F., following which the platinum was reduced to the metallic state with hydrogen at 450" F. The platinum content of the finished catalyst was 0.48 per cent by weight. - This catalyst, designated as Catalyst No. 1, corresponds to a commercial reforming catalyst. EXAMPLE II A second portion of the reduced surface area silica-alumina component was treated with an 0.0214 molar aqueous solution of platinous tetramminochloride, Pt(NH3)4Cla, together with sufficient ammonium hydroxide to raise the pH of the solution to 11.1, the amount of solution being 1.2 cc. per gram of silica-alumina. The solution was held in contact with the silica-alumina for 20 hours at 210 F. to 212 F. Then the solution was drained from the impregnated silica-alumina base, and the base dried at a temperature in excess of 250 F. in a stream of nitrogen. Finally, the platinum on the catalyst was reduced to the metallic state with hydrogen at a temperature of about 950" F. This catalyst, Catalyst No. 2, contained 0.454 per cent by weight of platinum. EXAMPLE Ill A third portion of the reduced surface area silica-alumina component was treated with an 0.0203 molar aqueous solution of platinous tetramminohydroxide, [Pt(NH8)J(OH)2, for 18 hours at 212 F. The amount df solution used was 1.2 cc. per gram of silica-alumina. The solution was drained from the impregnated silica-alumina component and the component then was dried in a stream of nitrogen at a temperature in excess of 250 F. The platinum was reduced to the metallic state with hydrogen at about 950" F. The finished catalyst contained about 0. 465 per cent of platinuin by weight and is designated as Catalyst No. 3. EXAMPLE IV A fourth portion of the reduced surface area silica-alumina component was treated with platinous tetramminohydroxide by the method described in Example III to give a finished catalyst, Catalyst No. 4, having 0.355 per cent by weight of platinum. EXAMPLE V A fifth portion of the reduced surface area silica-alumina component was contact with an 0.0276 molar aqueous solution of platinous tetramminohydroxide in the proportions of 1.2 cc. of solution per gram of silica-alumina component. The solution was held in contact with the component for 18 hours at 212 F. The impregnated silica alumina

pellets were drained and dried at 250 F., then the dried impregnated pellets were calcined with air at a temperature of 650" F. to 7000 -F. for two hours. The finished catalyst, Catalyst No. -5, contained 0.620 weight per cent of platinum. Each of the catalysts prepared above was tested by the above described laboratory reforming stability test. It should be noted that each of the catalysts raised the clear octane number of the standard charge stock from 55 to 92 (at the 72 hour point) as measured by ASTM Method D 908-51. The results of the test and the stabilities found from Figures 1 and 2 for the catalysts are set forth in Table I. TABLE I impregnating Compound and Platinum Con tent of Decrease Increase in Total Catalyst Finished in Minimum Bed Stability Number Catalyst Octane No. Temperature - Number 1 H2Pt C16 2.5 6" F. 53 0.48% Pt. 2 [Pt(NH3)4]Cl2 4.0 6"F. 43 0.454% Pt. 3 [Pt(NH8)J(OH)2 2.0 10 F. 82 0.465% Pt. 4 [Pt(NII3)J(OIl)-2 3.1 2" F. 69 0.355% Pt. 5 [Pt(NI1,)4](OH)2 1.4 10 F. 86 0. 62% Pt. It is evident from the above data that the use of platinous~~ tetramminohydroxide for impregnating an acidic metal oxide component produces a catalyst having a very markedly improved stability. For example, a catalyst of the present invention shows a 60 per cent increase in stability over present commercially acceptable catalysts prepared by impregnation with cholorplatinic acid, comparing Catalyst Nos. 3 and 5 with Cata lyst No. 1. The catalysts of the present invention show a 95 per cent increase in stability over catalysts prepared by impregnation with platinous tetramminochioride, Catalyst No. 2. The data also show that a catalyst prepared according to the present invention is 30 per cent more stable than a commercial catalyst containing over 30 per cent more platinum, comparing Catalyst No. 4 with Catalyst No. 1. Consequently, the present invention permits very important savings in catalyst cost both by using less platinum on the catalyst and by providing catalysts having greatly increased life. The method of the present invention has been found to be effective in

the preparation of reforming catalysts for treatment of petroleum distillates, such as light hydrocarbons, naphtha, gasoline and kerosine, and particularly gasoline fractions. The fractions may have an initial boiling point within the range of 50 F. to 90 F. and an end boiling point of about 425 F. to 560t F. It is preferred when reforming petroleum distillates boiling in the gasoline-kerosine range to impregnate a silica-alumina metal oxide component having a surface area within the range of 10 to 65 square meters per gram with platinous tetramminohydroxide to give a platinum content of from 0.1 per cent to 2.5 per cent by weight of the finished catalyst, the catalyst after impregnation being finished by the conven tional methods outlined above. The reforming conditions for such charge stocks and with such catalysts include reaction temperatures within the range of 600 F. to 1000 F., pressures of from 100 to 1000 pounds per square inch, liquid hourly space velocities of from 0.1 to 10 and hydrogen to hydrocarbon mol. ratios of from 1 to 20 mols. of hydrogen per mol. of hydrocarbon. The method of the present invention has been found to be effective in preparation of catalysts using acidic metal oxide components having surface areas not only in the 10 to 65 square meter per gram range specified in the abovementioned patent, No. 686,641, but also acidic metal oxide components having surface areas greatly in excess -of the 65 square meter per gram area, including unaltered components and acidic metal oxide components which have been combined with an alkali metal compound. While the catalysts of the present invention are particularly useful in reforming processes, it is understood that they may be used in any process in which platinumcontaining catalysts are utilized. They may be used in the cracking of normally gaseous or normally liquid hydrocarbons, dehydrogenation of cyclic paraffins to aromatics, isomerization of organic compounds particularly the parafnnic and alkyl aromatic hydrocarbons, hydrogenation of unsaturated hydrocarbons to produce the corresponding saturated hydrocarbons, hydrogenation of unsaturated alcohols, aldehydes, ketones and acids. Other reactions in which these catalysts may prove useful include oxidation, condensation and polymerization. What we claim is: 1. A method of preparing a platinum containing catalyst, which comprises impregnating an acidic metal oxide component with an aqueous solution of platinous tetramminohydroxide, drying the impregnated acidic metal oxide component, and eonverting the platinous tetramminohydroxide impregnated on the acidic metal oxide component to metallic platinum.


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