US2375757A - Regulation of catalytic activity - Google Patents

Description

Ma 15, 1945. J, R'BATES 2375,75?

REGULATION OF CATALYTIC ACTIVITY Original Filed Au 12, 19:59

f" a m lb/m 2 v I5 I I0 v j x v F &a

no 900 1000 110a 120a 1400 M00 [600 1600 Temp "F AZI'TORNEY M... May 15, ms

UNITED ST TES PATENT oli-ics uncommon or CATALYTIC ACTIVITY 7 John B. Bates, Bwarthmore, Pa., assignor to Process Oorpwa .Hondry tion, Wilmington, DeL,

a corporation of Delaware continuation oi vapplication Serial No. 289,915.

All! 12,

- "194:. sci-n1 No. mass s Claims. (01. mos-s2) Thepresent invention relates to processes for preconditioningol active cracking catalyst for the cracking of selected types of charging stocks.

In the catalytic cracking of hydrocarbon materials for th production of gasoline it is wellknown that many other materials besides gaso- This coke represents a net loss sincehydrocarbons are used up in its production. Also the I greater the coke deposit the longer the regeneration period would have to be in proportion to the on-stream period in order not to exceed However, not all of the materials prodetrimental temperature levels during regeneration.

In the operation of catalytic cracking plants, prior to the present invention, the general practice has been to place an active cracking catalyst in the plant and to operate with that catalyst over a period of generally some weeks in aneconomically disadvantageous manner. The catalyst during this period undergoes changes and eventually comes to a condition in which the plant may be operated under economically desirable conditions. Whenever the catalyst has been renewed it has been necessary 1 to repeat the same breaking in operation. During this breaking in period, the capacity of the plant is substantially reduced due to the necessity of decreasing the amount oi oil fed to the catalyst and of introducing excessive amounts of steam for the purpose of limiting the amount oi coke to an amount which can be removed by regeneration without harming the catalyst or the equipment. with any particular active cracking catalyst, it has not been known how to overcome the disadvantage of the high coke formation by .such catalysts except by the above described control of cracking during the first several weeks of production.

It is accordingly an object of the present in- 1 vention to precondition active cracking catalysts.

' prior to use, whereby when a plant goes on -stream,itisunnecessarytoruntmeconomically initially. It is a further obiect hereof to modify the activity in the preconditioning step, whereby ll ganese, copper, cobalt, nickel, iron, chromium,

vanadium, thorium, titanium and molybdenum.

1989. This application June 16.

the activity, without being substantially killed, is shifted with resultant change in the relative roportion 0! products.

In accordance with the present invention the catalyst employed is a naturalor synthetic silicious cracking catalyst. Such catalysts contain one or more metal oxides, which in general are selected from .the group,. alumina, zirconia, and beryllia. The cataLvst is treated with steam at an elevated temperature under treating conditions suiiiciently severe that the gasoline to coke ratio is increased at least 25% and sumciently mild that the volume percent gasoline is not reduced more than 20% in the cracking oi."

a stock of the type to be employed. The catalyst is then employed, after such pre-treatment. for the cracking of a stock of the type for which it was conditioned.

Active silicious cracking catalysts oi the type to which the present invention relates may be either natural or synthetic. The natural catalysts are best illustrated by the activated clays suchasareknownintheartanddisclosedinU. 8. Patent No. 2,078,945 granted May 4, 1937, to Eugene J. Houdry. In clays the metal oxide present is alumina. Active synthetic, catalysts. to which the present invention applies, are dried gels, containing silica and one or more metal oxides. While the commonly employed metal oxides are of the group alumina, zirconia and beryllia, other metal oxides may be present, generally in small percentage, in addition to one of the three stated oxides, as for instance manlictive synthetic catalysts may be prepared by any suitable method as by coprecipitation oi the silicaand metal oxide, by separate precipitation and blending, or by the precipitation or one upon a suspension of the other. The best catalysts are substantially free of sodium and other alkali metals. containing less than 1% of alkali metal oxide computed on the basis of sodium oxide equivalent. Suitable methods 0! preparing such synthetic catalysts are disclosed in my copending applications SerialNos. 310,782 and 410,165. The present invention, however, is not limited to catalysts prepared by particular methods, but is of general application to silicious cracking catalysts. While in some respects the natural and synthetic silicious cracking catalysts are not fully equivalent. the two types appear in the present relationship to be substantially i'ull equivalents and to be ailected in generally the same manner.

along the line AB, and

The conditioning of the-catalyst is effected by a treatment with steam at a partial pressure of .at least'three-tenths of a pound per square inch.

at an elevated temperature, between 800 and 1650" l". The steam pressure employed, in general, varies inversely as the temperature, and should be correlatedwith the' temperature so' as to lie within the zone between the lines AB and CD, as shown. in the accompanying drawing. Within this zone the rate at which the activity of the catalyst is shifted from one type of activity to another type is relatively rapidso a short treating time may be used, on the order -of a day or less, and yet sumciently' slow that the time does not become so short that accurate control of the result is not obtainable. The

lines .AB and CD have been determined purely on a basis of the results obtained in the condialong the line CD, when T is the temperature of the treatment expressed in degrees Fahreniight gas oil a very limited treatment heit. It should be remembered that these two equations are purely empirical and based upon result and not upon theory;

The rate at which the preconditioning occurs 7 and the degree to which the catalyst is ailected are dependent, to a major extent, upon the selected conditions of treatment and upon the purity of the catalyst being treated. Thus, cond.itions toward the line CD are increasingly severe with resulting increase of rate, while condittons toward the line AB are milder with re suiting decrease in rate. with relatively impure materials, such as synthetic catalysts of, high alkali metal content, it is generally preferable to operate at conditions selected toward the line AB. More severe conditions are generally employed with the synthetic catalyst containing less than 1% alkali metal compounds. with activated clays, such as disclosed in the aforementioned Houdry patent, it is preferred that the temperature and pressure be correlated to fall below the iineEI'. AlongthelineEFthepartiaipressureof steam equals -scs.

In this range, below the line 121', very accurate reduplication of preconditioning is obtainable.

The severity of the treatment, 1. e.. the extent of modification of the catalyst, is accordingly a function both of the severity of treating conditions and of length of time the catalyst'is treated. In accordance with this invention the catalyst is treated in the preconditioning step at asrsnsr recoveryisconsiderably increased. The reduction ofthearnountofcokeissomuchgreaterinproportion to the reduction in the amountci'gasolinethattheratioofgssolinetocokeislncreased .morethan25%.- whenthestocktobecrackedis a very heavy gas oil, often termeda heavy residuum from which the heavy tar has been removed. a'much more severe treatment is used.

The results obtained in comparative cracking tests catalyst but.lsatreatmentwhichshifts theac tivity thereof.

It isin'general preferred to operate at a partial pressure of steam below 100 lbs. However. if desired, suitable treating conditionscan be selected at higher partial-pressures of steam than 100 lbs. at temperatures above 800 Rand at parttal pressuresofsteambelowthelineCD. u 1

A special application of the present invention involves the preconditioning of synthetic silicious cracking catalysts for the cracking of naphthas and light gas oils boiling up to about 000 1". For such a charge, it is preferred to eil'ect a very mild oonditioningof the catalyst such that the gasoline produced is decreased not more than 10%, which treatment is eflected at a temperature of 1400 F. or higher and at a partial pressure of steam below 10 pounds. Catalysts of this variety are oi great utility in the production of aviation gasolines, as disclosed in my copending applications Serial Nos. 365,923 and 365,924.

The range of conditions under which catalytic cracking is effected is known in the industry asisalsothegeneral typeofopera'tlon. Itistobe noted, however, that the present invention is applicable both to plants employing a stationary catalyst and alternate on-stream and regeneration periods, and to plants in which the catalyst moves in cycle through a cracking zone wherein it is on stream and through a regeneration zone "adjusted activity of the catalyst is maintained least sufliciently that the ratioof gasoline to coke produced in cracking is increased 25%. and is limited sufllciently that the amount of gasoline produced is not decreased more than 20%. The

actual extent of modification of the catalyst to eil'ect this result varies considerably with the type of charge stock to be cracked.

The severity of the treatment of the catalyst The present invention is more trated in the following examples.

Example 1 specincallyillus- Solutions of sodium silicate and sodium alumiwithout substantial change "for many months of of about 12:1 were mixed to form a sol to, which a suillcientquantity of ammonium sulphate was added to yield a gelatinous coagulum having a and were employed for cracking alight East 4 heavy stock, as shown, very advantageous repH of the order of 9.5. After drying. the coagu mm was treated with an ammonium chloride so: s

Texas gas oil fraction having an A. P. I. gravity of about 86 and a boiling range of about 440 to 720' l"., at a catalyst temperature of 000' 1"., at atmospheric pressure and at a rate of 1% vol. umes liquid charge per liter or catalyst per hour. The results obtained in cracking under these conditions with the catalyst not preconditioned and after preconditioning are shown in the table:

Steam treatment conditions Cracking results F. Por- 8'!!! E. P. Temp I Time, gasoline 22:23 gr m: :gh f gs: oi chg. oi charge 1 41 s. a n 2. 1,250 3 2 If. 3.9 7.1 3.;-.. 1.400 0.75 46.7 3.8 7.6 1-.. 1,000 2 41.1 3.2 7.1 I 5..... 900 5 2 39.1 2.5 4.4 5..." 1,330 15 G 34.4 1.5 2.8 etc is sau azu 1.0 at I"... I m ll N? 6 H. 1., 2.4 9 I, 45 2 25.7 0.0 1.2 10... I. 75 m. 0.6 1.3

ltistobenoted thatforthecrackingofthis.

ype of stock the preconditioning of portions 2 to 0 produced advantageous'results, whereas the preconditioning of portions 8 to 10 was so severe that for this type of stock these catalysts were unsuitable. The gasoline to coke ratio of per-- tlon 1 was 9.05. The ratios of portions 2 to 5 were respectively: 12.; 14., 18.. and 17.. which shows that the increases ranged between 80% and 90% in these instances.

Portions 1 and 6 were employed for the cracking of a heavy residuum oi an East Texas crude suits are produced. Further. it is interesting to 7 note that in cracking the heavy stock, the liquid recovery was increased from 76.3 for portion 1, a

to 08.8 for portion 6.

Portion 9, which likewise was treated too severely for the cracking of light stock, was utilized for transforming highsulphur crude from Santa Maria field in California into high octane motor fuel. In this operation the entire crude.-which had an A. P. I. gravity of about 15.7 was rapidlyv heated to about 900 F. in the presence of about 20% by weight of steam and the resulting vapors were separated from unvaporized material. These two steps were conducted under such conditions. including high rate of feed and low pressure, as to minimize thermal cracking into gasoline and gas. The vapors, making up about 99.4% or the originalcrude, were passed over catalyst identifled as portion 9, at a pressure of about 8 lbs. per sq. in. gage and a rate of about 3 volumes of charge per volume of catalyst per hour. There was thereby obtained 46% by volume based on charge of 400 I". end point motor fuel, with the concomitant production of 3.4% by weight of coke and 2.6% by weight of gas. There was also obtained 54% by volume of a clean recycle stock having an A. P. I. gravity of 20.

Erample 2 An activated clay was employed as a catalyst and had the following approximate composition:

I Silica 67.06 Aluliiina. 15.73 l 'esOs....--' 2.63 Ca oxide 1.36 Mg oxide 4.17 NasO .57 Moisture 16.07 Ignitionloss 8.16

This catalyst was tested in the cracking of a scribed in Example 1, the cracking being conprepared by removal of the initial 58% of the crude and 12% ot'the heavy ends. which heavy residuum had an initial boiling point oi about 550 and an end point of about 1000' I"; the re- -mainder being sumciently high boiling that it was impossible to determine the range. The cracking was performed at a rate of twenty volumes liquid basis of the charge per volume of catalyst per hour, at a temperature of 835 l"., a pressure oi 7 lbs/sq. in. and in the-presence of 20% steam. The comparative'results are shown in the following table:

ayufl sfimmmentor orucn 0.whilethe too eevercfor lights l oil. for a ducted at a rate of 1 volume liquid basis of feed' per volume of catalyst per hour, at a catalyst temperature of 850 I"., under a pressure or 7 lbs. per sq. in. gage with 15% steam. Under these conditions a liquid recovery of 75.4% by volume of charge was obtained, which yielded 43% by volume gasoline. based on charge. Gas was produced during the cracking to the extent of 22% by weight of the charge and coke was'lald down on the catalyst to the extent of 8.2% by weight of the charge. Clay of this type was treated with steam at a partial pressure of 15 lbs. for 8 hours at 1830' l". The same charge stockwas cracked under identical conditions. With the catalyst so treated the liquid recovery was increased to 93%. the gasoline to 44%, while the gas was decreased to 9.9% and the coke to 4.2%. The ratio or gasoline to coke with the untreated catalyst was 5.25. whereas with the treated catalyst the ratio 10.5, an increase or in the ratio.

A similar clay catalyst was employed for the cracking of a light East Texas gas oil under the conditions stated in Eaxample 1, whereby there was produced a yield of 40.9% by volume of gasoline. 8.9% by weight of coke and 5.1% by weight of wet gas. Catalyst of this character was steam treated at 1150' I. for four hours at a partial 7 pressure of steam or 15 lbs. per sq. in. when employed for smoking a light East Texas gas oil under identical conditions a yield of 34.5% by was Warm byweisiitorcossmsam by weight or gas; The ratio or gasoline-to coke was increased about2 5% bythetreatment.

summer A silica sir'conia synthetic cracking catalyst was prepared by iorming a sol oi zirconium sulphate'and sodium silicate containing. 810: and ZI'O: in molar ratio oi 15.1 to 0.755, enough sulphuric acid beingadded to bring the pHto 6.0. The precipitated material was dried, washed, treated with ammonium chloride to tree it 01' sodium, following which the catalyst was hardened at I050 1". i'or two hours in air. When employed for the cracking of a light East Texas gas oil under the conditions stated in Example 1, a yield oi 47.8% gasoline by volume was obtaincd.with the production of 6% by weight of coke and 4.2% by weightoi gas, which had a specific gravity oi 1.35. The catalyst was steam treated at 1400 l". tor 10 hours in 5% steam;

l. The process which comprises catalytically cracking a hydrocarbon charge stock heavier than asoline in the presence oi an active silicious A cracking catalyst which has been preconditioned tor the cracking oi said charge stock by subjecting v the catalystto contact with steam at apartial pressure above 0.3 pound per square inch and a temperature between 800 I". and 1650' It, the partial pressure of steam being correlated with the temperaturetoliebetweentheli'nesABandDCin the accomp yin drawing and for a time sufiicient to increase the gasoline to coke ratio at least 25% and insufiicient to elect a decrease of more than in the gasoline produced in the cracking oi'said charge stock.

ture to lie between the lines AB and CD in the accompanying drawing and for a time sufilclent I to increase the asoline to coke ratio at least %.v and insufiicient to eil'ect a decrease of more than 20% in the gasoline production in the cracking oi the selected type oi charge stock.

3. The process which comprises the steps of preconditioning an active sllicious cracking t pe of catalyst for the conversion or a selected type of conversion or said hydrocarbon charge stock.

and subjecting said hydrocarbon charge stock to said conversion in contact with'the catalyst so preconditioned.

4. The process which comprises the steps of preconditioning an active silicious cracking catalyst for the catalytic cracking'oi a selected type or heavier than gasoline charge stock by subjecting the catalyst to contact with steam at a partial pressure above 0.75 pound per square inch and a temperature between 800.F. and 1650' F the parti'al pressure oi steam being correlated with the temperature to lie between the lines AB and CD in the accompanying drawing and for a time sufiicient to increase the gasoline to coke ratio at least 25% and insufiicient to efiect a decrease ,or more than 20% in the gasoline production in the cracking oi the selected type oi charge stock, and catalytically cracking the selected type of stock in the presence or the catalyst so preconditioned.

. 5. The process which comprises the steps of pre- I Y conditioning an active sllicious cracking catalyst for the catalytic cracking of a selected type of heavier than gasoline charge stock by subjecting the catalyst to contact with .steam at a partial pressure above 0.3 pounds per square inchand a temperature between 800 F. and 1650" It. the pressure 01 steam beingcorrelated with the temperature to lie between the lines AB and CD in the accompanying drawing and'i'or a time sufiicient to increase the gasoline to coke ratio at least 25% and insumcient to efi'ect a decrease oi more than 20% in .the gasoline production in the cracking oi the selected type oi charge stock, and catalytically cracking the selected type or stock in the presence or the catalyst so preconditioned.

6. The process which comprises the steps 0! preconditioning an active sllicious cracking catalyst for the catalytic cracking of a selected type 01' heavier than gasoline charge stock by subjecting the catalyst to contact with steam at a partial pressure above 0.8 pound per square inch and a temperature between 800 and l650 1"" the P rtial pressure oi steam being correlated with the temperature, the partial pressure in pounds per 2. The process which comprises preconditionin 511 square mob hem: mater than an active sllicious cracking catalyst for the catal- I ytic cracking oi a selected type of heavier than 35.4xl0 6 gasoline charge stock by subjecting the catalyst 'T' to contact with steam at a partial pressure above and less than M 0.8 pound per square inch and a temperature be- M tween 800 1''. and 1850' F., the partial pres- X sure oi steam being correlated withgthe temperawhen T is equal to the temperature in degrees Fahrenheit and for a time suificicnt to'increase the gasoline to coke ratio at least 25% and insuiil cient to' effect a decrease or more than 20% in the gasoline production in the cracking of the selected type of charge stock, and cracking the selected time oi stock in the presence oi the catalyst so preconditioned.

. o arbon charge stock under conditions that .7. The process defined in claim 6 in which the gasoline boiling range materials arecontained in the efiiuent product and coke-like material is deposited in thecatalyst, by subjecting the catalyst to contact with steam at a partial pressure above 0.3 pound per square inch and a temperature between 800)". and 1660 E, the partial pressure of steam being correlated with the temperatureto'liebetweenthelinesABandCDintheac g 354x 10 we preconditioned catalyst during the cracking ste when T is equal to the catalyst temperature in de- Ines Fahrenheit at the time of contact with steam.

8. The process which comprises the steps of preconditioning an active silicious gel type cracking catalyst for the cracking of low boiling hydrocarbon material heavier than gasoline for the production of gasoline by subjecting the catalyst to contact with steam at a partial pressure oi steam between 0.3 and 10 pounds per square inch and at a temperature above about 1400 F. and below the line'CD correlated with thesteam pressure as shown in the accompanying drawing, and cracking a low boiling heavier than gasoline hydrocarbon' material in the presence of the catalyst so preconditioned.

JOHN R. BATES.

CERTIFICATE OF CORRECTION.

Patent No. 2.575.757-

orIzhzsalsereby certified that error appears in the printed specification ove numbered patent requiring correction as followsond column, line 35, after "vanadium," insert "tungsten I and column, line 67, for "Eaxample" read -t-Exa.mple-- I Let ters Patent should be read with this correction therein that the same 7 May 15 l JOHN R. BATES. 945

may conform to the record of the case in the Patent Office Signed and sealed this. 11th day of September, A. D. 1914.5

(Seal) Leslie Frazer Page 1, secand that the said when T is equal to the catalyst temperature in de- Ines Fahrenheit at the time of contact with steam.

8. The process which comprises the steps of preconditioning an active silicious gel type cracking catalyst for the cracking of low boiling hydrocarbon material heavier than gasoline for the production of gasoline by subjecting the catalyst to contact with steam at a partial pressure oi steam between 0.3 and 10 pounds per square inch and at a temperature above about 1400 F. and below the line'CD correlated with thesteam pressure as shown in the accompanying drawing, and cracking a low boiling heavier than gasoline hydrocarbon' material in the presence of the catalyst so preconditioned.

JOHN R. BATES.

CERTIFICATE OF CORRECTION.

Patent No. 2.575.757-

orIzhzsalsereby certified that error appears in the printed specification ove numbered patent requiring correction as followsond column, line 35, after "vanadium," insert "tungsten I and column, line 67, for "Eaxample" read -t-Exa.mple-- I Let ters Patent should be read with this correction therein that the same 7 May 15 l JOHN R. BATES. 945

may conform to the record of the case in the Patent Office Signed and sealed this. 11th day of September, A. D. 1914.5

(Seal) Leslie Frazer Page 1, secand that the said

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