US2791544A - Method of using a single reactor for a plurality of conversions - Google Patents

Description

May 7, 1957 S. C. EASTWOOD METHODOF USING A SINGLE REACTOR FOR A PLURALITY OF CONVERSIONS Filed July 25. 1952 2 Sheets-Sheet l INVENTOR. 5Y1. VANDEE 6 545701000 United States Patent METHOD OF USING A SINGLE REACTOR F OR A PLURALITY OF CONVERSIONS Sylvander Cecil Eastwood, Woodbury, N. 1., assignor to Socony Mobil Oil Company, Inc., a corporation of New York Application July 25, 1952, Serial No. 300,861

Claims. (Cl. 196-52) The present invention relates to hydrocarbon conversions and, more particularly, to a means whereby one reactor can be used for the purpose of subjecting a hydrocarbon mixture to a plurality of conversions in the presence of the same particle-form catalyst under a plurality of operating conditions of different severities.

Thus, for example, it is well-known that in general it is usual to provide more severe conditions for reforming than for desulfurizing a mixture of hydrocarbons. In the past, reforming and desulfurizing of the same feed has been obtained employing the same catalyst but requiring two reactors or converters. It has now been discovered that a plurality of conversions can be obtained in the same convertor or reactor by controlling the residence time and the reaction temperature.

It is an object of the present invention to provide a method of operating a single convertor to obtain desulfurization in one portion of the converter and reforming in another portion of the convertor whilst passing the same particle-form solid contact material through both the reforming zone and the desulfurizing zone whilst maintaining sufiiciently severe conditions in the one zone to obtain reforming of the hydrocarbon charge stock therein and less severe conditions in the desulfurizing zone to obtain practical desulfurization of the hydrocarbon charge stock therein. It is another object of the present invention to maintain the more severe conditions in the reforming zone by supplying the major or controlling portion of the heat required in that zone in the catalyst or particle-form solid contact material while main taining less severe conditions in the desulfurizing zone by supplying the major or controlling portion of the heat required in the desulfurizing zone in the hydrocarbon charge stock. It is a further object of the present invention to facilitate the control of residence time and reaction temperature in the desulfurizing zone through bypassing effectively with respect to the hydrocarbon charge stock a portion of the catalyst entering the desulfurizing zone. It is also within the scope of the present invention to provide means for controlling the residence time and reactor temperature in a plurality of zones whereby a plurality of reactions in the presence of the particleform catalyst can take place simultaneously. Other objects and advantages will become apparent from the following discussion taken in conjunction with the drawings in which,

Figure l is a schematic illustration of one embodiment of the present invention in which a portion of the particle-form solid-contact material or catalyst in one zone is by-passed with respect to the hydrocarbon charge stock; and

Figure 2 is a schematic illustration of another embodiment of the present invention in which a portion of the catalyst is by-passed in one zone;

Figure 3 is a schematic illustration of another embodiment of the present invention in which a portion of the 2,791,544 Patented May 7, 1957 catalyst is not bypassed but reaction conditions are controlled by means of the catalyst-to-oil ratio.

It is generally accepted that the term desulfurization or "desulfurizing means reducing the sulfur content of a hydrocarbon charge stock. One method known to the art is that of catalytic desulfurizing or catalytic desulfurization. In catalytic desulfurizing a hydrocarbon charge stock, the charge stock is contacted with a suitable desulfurizing catalyst of which many are known to the art at elevated temperatures in the presence or absence of hydrogen or hydrogen containing gas for a period of time suflicient at the temperature selected to reduce the sulfur content of the hydrocarbon mixture to a practical extent. A limitation upon the desulfurizing conditions is the practical requirement that the loss through decomposition be kept low while achieving a reduction of the sulfur content necessary to provide prod ucts which will meet specifications. Under such conditions, which relative to reforming conditions are relatively mild, the octane number of the charge stock is not raised effectively.

It is generally accepted that the term reforming or aromatizing" or cyclizing is applied to a plurality of reactions occurring simultaneously or successively or both, in which a primarily aliphatic hydrocarbon charge stock is converted to a product having a higher octane number and a higher content of aromatic hydrocarbons than the charge stock.

For the desulfurizing conversion, the temperatures required are about 650 F. to about 900 F. and preferably about 700 F. to about 800 F. For the reforming conversion the temperatures required are about 825 F. to about 1025 F. and preferably about 875 F. to about 950" F.

The terms desulfurizing" or desulfurization and, reforming or aromatizing or cyclizing" are used herein in the sense briefly discussed hereinbefore.

In general, the present invention provides for a reforming zone and a desulfurizing zone in series relation through which the particle-form catalyst passes as a compact column. That is to say, the catalyst passes through one zone as a compact column, enters the other zone and passes therethrough as a compact column. However, since the conditions in the desulfurizing zone are much less severe than the conditions in the reforming zone, means must be provided for controlling the heat absorbed by the hydrocarbon charge stock in each zone to provide the severity of conditions necessary to maintain desulfurization without excessive loss and reforming without excessive loss.

The catalyst leaves the kiln or regenerator at a temperature of about 1000 to about 1100 F., and preferably about l000 to about 1050 F., and enters the first conversion zone at a temperature of about 975 to about 1075 F. and preferably at about 975 to about 1025 F. In accordance with the principles of the present invention, the reforming or desulfurizing temperature is obtained in the respective zones by regulating the rate of the hydrocarbon stream to make either the catalyst or the hydrocarbon stream controlling of the temperature. In other words, the ratio of catalyst to oil is controlling. Thus, the stock to be desulfurized and reformed can enter at the lower end or bottom of the reactor having a lower desulfurizing zone and an upper reforming zone and flows upward counter-current to downwardly flowing catalyst at a catalyst-to-oil ratio such that the oil inlet temperature controls the temperature of the zone. In the upper or reforming zone the catalyst-to-oil ratio is such that the catalyst inlet temperature is controlling.

In general, for producing reforming conditions, the catalyst-to-oil weight ratio, i. e., C/ H, is about 4 to about S and preferably about 4 to about 6, and the Space velocity is about 1.0 to about 3.0 and preferably about 1.5 to about 2.0 liquid volume of charge stock per unit volume of catalyst in the reforming zone.

in the desulfurizing zone the charge stock inlet temperaturc is about 650 to about 850 F. and preferably about 700 to about 800 F. The catalyst to oil weight ratio, i. c., C/H is about l.0 to about 3.0 and preferably about 1.5 to about 2.0 and the space velocity is about 0.25 to about 1.0 and preferably about .50 to about 0.75 liquid volume of charge stock per unit volume of catalyst in the desulfurizing zone.

in general, the reaction temperature in the dcsulfurizing zone is about 650 to about 850 F., and preferably about 700 to about 800 F., while in the reforming zone the reaction temperature is about 825 to about 1025 F. and preferably about 875 to about 950 I.

Those skilled in the art will note that the catalyst-to-oil ratio in the desulfurizing zone is lower than in the reforming zones. To achieve these ends one can either contact a given volume of charge stock with a lesser volume of catalyst in the dcsulfurizing zone than in the reforming zone, or contact a lesser volume of hydrocarbons with a given volume of catalyst in the reforming zone than in the dcsulfurizing zone.

In the first alternative, a portion of the catalyst by passes the dcsulfurizing zone. In the second alternative, an auxiliary reforming zone can be employed or the reforming zone can have a catalyst volume proportional to the catalyst volume of the desulfurizing zone. For practical reasons it is presently preferred to have the catalyst bypass the desulfurizing zone.

Turning now to the drawings, the method of the pres cnt invcntion will be described first by following the course of the catalyst through the process, then by following the hydrocarbon charge through the process.

Referring to Figure l and using as an illustrative example of the plural treatment of a reactant in a single multi-zone reactor the desulfurizing and reforming of a mixture of hydrocarbons containing hydrocarbons capable of undergoing isoinerization. and/or dehydrogenation and/or dchydrocyclization. all of which molecular changes are included generally in the designation, reforming, the course of the catalyst through a plurality of zones, i. c., a desulfurizing zone and a reforming zone will first be followed, and then the path of the mixture of hydrocar' boos will be traced.

Active catalyst. for the purposes of the illustration--an alumina-silica cracking catalyst such as natural clays tfullers earth), treated natural clays ("Super-Filtrol"), and synthetic associations of silica and alumina usually in gel form to which can be added other metals or metal compounds for special purposes, is placed in feed bin 11. The catalyst can also be a group Vl metal or metal compound as ociated with alumina or silica or in general any particle form catalyst which is suitable for producing any one or all of the molecular changes generally denominated, "ison1erization." dehydrogenation and dehydrocyclization."

The catalyst at a temperature of about 950 to about 11 0 F. and preferably at about 975 to about 1025 F. when using a cracking catalyst, flows from feed bin 11 through conduit 12 into surge chamber 13. From surge chamber 13 the hot active catalyst flows through conduit 14 into reactor 15 as a substantially compact column.

Reactor 15, as illustrated, is divided into two zones, an upper reforming zone 16 and a lower, annular desulfuriz ing zone 17. Zones 16 and 17 are preferably of correlated volumes whereby the residence time and/or the catalystto-oil ratio are correlated with the reaction temperatures in both zones to provide the more severe reforming conditions in reforming zone 16 as compared to the relatively mild desulfurizing conditions in annular desulfurizing zone 17.

As illustrated in Figure 1, such correlated control is til) provided by the catalyst by-pass 18. That is to say, the hot catalyst flows as a substantially compact mass downwardly through reforming zone 16 to a point such as "A" where the catalyst is divided into two portions, to wit: a central stream which flows as a substantially compact column through by-pass l8 and, as illustrated, an outer annular substantially compact hollow column 17.

By-pass 18 is of any suitable type whereby a portion of the catalyst mass is separated from the rest of the catalyst flowing through the reactor and maintained out of effective contact with the reactant to be treated in the desulfurizing zone.

In the drawing Figure l, by-pass 18 is shown as a hollow, cylindrical column provided at its lower end with a flaring skirt. The cross-sectional area of the flared skirt is proportioned to the total crossscctional area of the reactor or catalyst column to divert suihcient of the total catalyst column to provide in desulfurizing zone 1.7 the catalyst-to-reactant ratio required to provide the milder conditions necessary in zone E7.

The catalyst to reactant ratio in zone 17 will be, as those skilled in the art. know, dependent upon the temperature of the catalyst, the reaction temperature and the volume of reactant to be treated.

The by-passed catalyst flows as a substantially compact column through by-pass 13. The balance of the catalyst: flows as a substantially compact annular column through annular zone 17. The two columns join in area 41 at the bottom of the reactor and flow as a single substantially compact column from the reactor through conduit 19 to chute 20.

Generally, the catalyst in passing through the reactor becomes more or less inactivated. For economical reasons it is necessary to reactivate the catalyst. in many catalytic reactions the catalyst can be r .i'ivated by combustion of the deactivating contamin: t in a stream of combustion-supporting gas. Since the reforming and dcsulfurizing of a mixture of hydrocarbons results in the contamination of the catalyst with a carbonaceous deposit gcnerally called coke, the reactiwtion of the catalyst has been illustrated in Figure l as taking place in a kiln or regenerator 25. Accordingly, the deactivated catalyst flowing from reactor 15 through conduit 19 passes into chute 20 and thence to any suitable means for trans fcrring the deactivated catalyst to the regcncrator.

The catalyst transfer means can be .i it. an elevator or the like suitable for transferring particle form catalyst from the reactor to a regenerator. As shown in Figure l in a schematic manner, the catalyst transfer means is an elevator, preferably a bucket elevator. The design of such and other catalyst transfer devices are so well-known to those skilled in the art as to require no description particularly since the present invention is not concerned with the design of catalyst transfer means.

The deactivated catalyst passes through chute 20 to the boot 42 of elevator 21. The deactivated catalyst is raised to head 43 of elevator 21 and discharged into chute 22 along which the deactivated catalyst flows to feed bin 23 of regenerator or kiln 25.

Regencrator or kiln 25 is of an "able design it herein the carbonaceous contaminant or can be burned off in a stream of combustionsupporting gas such as air. Since the present invention is not co ccrncd with the design of such regenerators or kilns an iucc the design of such rcgencrators or kilns is well-kno to those sk lled in the art, the present invention is not limited to any particle lar regenerator.

The deactivated catalyst flows from 1' nor feed bin 23 through conduit 24 into kilr ,c, in a heated stream of combustion-supporting gas such as air. the coke is burned-off at a temperature below the damaging tcrnperature at which the particular catalyst is deactivated in such a manner as to be practically useless a catalyst for the reaction. For the catalysts of this illustration, the damaging temperature is in excess of 1400 F. Conse quently, the temperature in kiln or regenerator is not greater than about 1400 F. and can be as low as 950 F.

During passage through kiln 25 the coke deposit on the catalyst is burned-off and the catalyst reactivated. The hot reactivated catalyst flows from the kiln through conduit 26 into chute 27 and thence to any suitable catalyst transfer means whereby the reactivated catalyst is raised to reactor feed bin 11. The catalyst transfer means can be a gas lift or the like, an elevator, etc. suitable for transferring catalyst from chute 27 to reactor feed bin 11. As illustrated, the catalyst transfer means is a bucket elevator similar to that by which the deactivated catalyst is transferred from reactor 15 to kiln 25. However, catalyst transfer means can be used to transfer the catalyst from the kiln to the reactor differing in type from that used to transfer the catalyst from the reactor to the kiln.

As shown, the catalyst flows along chute 27 to elevator boot 44 of bucket elevator 28 by which it is raised to head 45 of elevator 28. From head 45 of elevator 28 the hot reactivated catalyst flows along chute 29 to reactor feed bin 11 ready to begin another cycle.

It will be noted that the operation illustrated in a schematic manner in Figure 1 is one in which the reaction takes place at substantially the same pressure as that at which the deactivated catalyst is regenerated. Those skilled in the art will recognize that when the reaction takes place at a pressure higher than that at which regeneration is carried out means must be provided to transfer the reactivated catalyst from a zone of lower pressure to the zone of higher pressure and to transfer the deactivated catalyst from the zone of higher pressure to the zone of lower pressure. For example, when the reactor is operated at super-atmospheric pressure and the regenerator at a lower pressure, a pressure lock is inserted between feed bin 11 and surge chamber 13 and between conduit 19 and chute 20.

The reforming and desulfurizing operations illustrated schematically in Figure 1 provide for counter-current flow of catalyst and reactant. The catalyst flows downwardly through zones 16 and 17 while the reactant flows upwardly. Thus, a mixture of hydrocarbons containing hydrocarbons which can be isomerized and/ or dehydrogenated and/or dehydrocyclicized in the presence of a particle-form catalyst, for example, a virgin naphtha is drawn from a source not shown and passed through line 30 into furnace 31. In furnace 31 the naphtha to be desulfurized and reformed is heated to a temperature such that at a pre-determined catalyst-to-oil ratio and with the catalyst at a pre-determined temperature in zone 17, desulfurizing of the naphtha takes place. For example. with the catalyst entering the desulfurizing zone at a temperature in the range of 850 to 950 F., the virgin naphtha is heated to about 650 to about 850 F. and preferably about 700 to about 800 F. in furnace 31. The heated naphtha leaves furnace 31 through line 32 under control of valve 35. The heated naphtha is distributed over the cross-section of annular desulfurizing zone 17 by a distributor 46 of any suitable design. By regulating the catalyst-to-oil ratio in annular zone 17, the reaction temperature suitable for desulfurizing the naphtha with substantially no loss of naphtha is maintained at about 650 to about 850 F. and preferably, at about 700 to about 800 F.

The naphtha flows upwardly in annular zone 1) countercurrent to the downwardly fiowing catalyst and during its contact with the catalyst is at least partially desulfurized upon entering reforming zone 16.

Upon entering reforming zone 16, the catalyst-to-oil ratio is changed because substantially all of the vapors of naphtha which contacted only the portion of the catalyst flowing through zone 17 new contacts the total volume of catalyst flowing through reforming zone 16.

The catalyst entering reforming zone 16 generally will have a temperature of about 975 to about 1075 F. and

preferably about 975 to about 1025 F. The catalyst entering desulfurizing zone 17 generally will have a temperature of about 850 to about 950 F. The naphtha or other mixture of hydrocarbons to be desulfurized and re formed entering zone 17 will have a temperature of about 650 to about 850 F. and preferably about 700 to about 800 F.

Under these conditions the catalyst-tomaphtha weight ratio, i. e., C/H, is about 4 to about 8 and preferably about 4 to about 6 in reforming zone 16 and about 1 to about 4 and preferably about 1.5 to about 2 in the desulfurizing zone. Accordingly, by-pass 18 is of such dimensions as to by-pass sufficient catalyst to provide the required catalyst-to-naphtha weight ratio. In other words. about 60 to about 75 percent and preferably about to about percent of the catalyst from the reforming zone passes through bypass 18 while the balance, about 25 to 40 and preferably about 30 to about 35 percent of the catalyst, is in effective contact with the naphtha in desulfurizing zone 17.

The at-least-partially desulfurized naphtha flows upwardly through reforming zone 16 where the molecular changes, generally classified as reforming, occur. The dcsulfurized and reformed naphtha flows from reforming zone 16 through outlet 38, cooler 39 and line 40 to means for stabilizing and fractionating the effluent and subjecting the eflluent to such after-treatment as is necessary.

When it is desirable or necessary, the desulfurizing of the charge stock can take place in the presence of hydrogen. For this purpose hydrogen or preferably a hydrogen containing gas containing about 35 to about percent hydrogen and the balance C1 to Ca hydrocarbons is drawn from a source not shown, heated in a furnace not shown to about 800 to about 1100 F. and preferably to about 900 to about 1000" F. and drawn through pipe 33 regulated by valve 36 and admixed with the charge stock in line 32.

Similarly, when desired or required, the reforming reaction can take place, as is well-known, in the presence of hydrogen or a hydrogen containing gas drawn from a source not shown through lines 33 and 34 under control of valve 37, and introduced into reforming zone 16 through one or more inlets and distributors not shown.

In the event that a recycle gas of low hydrogen content or devoid of hydrogen or any other gaseous reactant or heat carrier is to be used in conjunction with a liquid reactant, the gaseous reactant can be introduced into either or both zones by means of pipes 32 and 34.

Figure 2 is a schematic illustration of an arrangement of a plurality of reaction zones in a single reactor or convertor through which a particle form catalyst flows successively wherein the reactant and catalyst flow concurrently and the first zone through which the catalyst flows is the zone of relative mild reaction conditions and the second zone of relatively severe reaction conditions in contrast to the converse as illustrated in Figure 1.

As in Figure 1, the course of the catalyst will be followed through the reactor and then a description of the path of the reactant or reactants through the reactor will be traced. For purposes of illustration, only the multizone single reactor is illustrated in Figure 2 since a reforming and desulfurizing operation will be used for illustrative purposes.

For purposes of illustration, a cracking and desulfurizing operation will be described in which desulfurizing takes place under relatively mild conditions in desulfurizing zone 117 and cracking takes place in cracking zone 116.

Hot active catalyst from a feed bin such as 11 flows into a surge chamber such as 13 and thence through con duit 114 into desulfurizing zone 117 of reactor 115. Desulfurizing zone 117 is preferably annular in cross-section while by-pass 118 is circular. The cross-sectional areas of desulfurizing zone 117 and by-pass 118 are proportioned to provide a catalyst volume in zone 117 such that the catalyst-to-oil ratio is about 1 to 3, and preferably 1.5 to 2.0, and a space velocity of about .25 to 1.0 and preferably .5 to .75 when the catalyst enters the reactor at a temperature of about 975 to about 1075 F. and preferably about 975 to about l025 F. and the oil to be desulfurized and cracked enters the desulfurizing zone at about 650 to about 850 F. and preferably about 700 to about 800 F. Under these conditions of reactant and catalyst inlet temperatures. catalyst-to-oil ratio and space velocity, the average reaction temperature in desulfurizing zone 117 is about 650 to about 850 F. and preferably about 700 to about 800 F.

In order to provide the catalyst-to-reactant ratio required in the desulfurizing zone 117, about 60 to about 80, and preferably about 65 to about 70 pcrccut of the catalyst stream entering reactor 115 flows through bypass 118 and the balance, about to about 40 and preferably about to about percent flows as a substantially compact annular column through desulfurizing zone 117.

The two substantially compact columns, the cylindrical column flowing downwardly through by-pass 118 and the annular column flowing through desulfurizing zone 117 join at B and continue to flow downwardly as a single compact column through cracking zone 116. When the catalyst reaches the bottom of reactor 115, it is more or less deactivated with a carbonaceous contaminant generally called coke in the industry. The deactivated catalyst flows from the reactor through conduit 119 to suit able transfer means, and thence to a rcgencrator or kiln such as kiln 25 of Figure l. The reactivated catalyst is then returned to the reactor feed bin ready for another cycle through the reaction zones and the regenerator.

A mixture of hydrocarbons suitable for cracking and requiring desulfurizing, such as a gas oil is drawn from a source not shown through line 130 and heated to at least a desulfurizing temperature in furnace 131. A temperature of about 650 to about 850 F. and preferably about 700 to about 800 P. will usually provide satisfactory results. The heated oil is passed through line 132 under control of valve 135 to distributor 146 of any suitable design whereby the oil is distributed over the cross-section of annular desulfurizing zone 117.

The oil enters the desulfurizing zone at a temperature of about 650 to about 850 F. and preferably about 700 to about 800 F. at such a rate to provide a catalystto-oil ratio in desulfurizing zone 117 of about 1 to about 4 and preferably about 1.5 to about 2.0 and a space velocity of about .25 to about 1.0 and preferably about .5 to about .75.

The oil flows concurrently downwardly with the substantially compact hollow cylinder or annulus of catalyst through desulfurizing zone 117. During this contact the oil is at least partially desulfurized. The downwardly flowing catalyst and reactant flow from desulfurizing zonc 117 into cracking zone 116 where the reactant contacts not only the catalyst from zone 117 but also the catalyst from by-pass 118. However, since the volume of catalyst effectively contacted by the volume of reactant lea ing desulfurizing zone 117 is appreciably greater, the catalyst-to-oil is increased and the temperature is in creased. Consequently, the reaction conditions are more severe. in the cracking zone 116 the catalyst-to-oil ratio is about 4 to about 8 and preferably about 4 to about 6 and the space velocity is about 0.5 to about 4.0 and preferably about l.0 to about 2.0.

The eliluent from the desulliurizing zone flows concurrently downwardly with the substantially compact column of catalyst through cracking zone 116. The catalyst leaves zone 116 via conduit 119 while the vaporous contents of zone 116 leave by way of line 138 to pass through cooler 139 and line 140 to after-treatment, stabilizing and fractionating equipment not shown.

When desirable or necessary, a gaseous heat carrier or a gaseous reactant can be mixed with the heated liquid reactant in line 132. Such a gas can be drawn from a source not shown through line 133 under control of valve 136. Furthermore, when necessary, a gaseous heat carrier or reactant can be introduced into cracking zone 116 through pipe 134 and its associated distributor not shown under control of valve 137.

Since, for purposes of illustration, the desulfurizing and cracking of a gas oil has been described, those skilled in the art will understand that the catalyst can be any suitable cracking catalyst such as natural clays, such as fullcr's earth, treated clays such as Supcr-Filtrol, syn thetic associations of alumina and silica usually in gel form with or without other metals or metal compounds; added for special purposes and the like.

Figure 3 provides a schematic illustration of It means for carrying out two reactions with the same catalyst under different conditions of severity wherein the capacity of the zone in which the less severe conditions prevail is appreciably greater than the capacity of the zone wherein the more severe conditions prevail. As before, the course of the catalyst through reactor 215 and auxiliary reactor 246 will he followed and then the course of the vaporous reactants through reactor 215 and auxiliary reactor 246 will be traced.

Hot active catalyst in bin 211 flows through conduit 212 into surge chamber 213. From surge chamber 223 hot activc catalyst flows into conduits 214 and 2H. tn the event that the capacity of zone 216 is sufficient to handle the total reactant from zone 21'? of reactor 255. conduit 244 is provided with a suitable shut-oii valve 24!.

The hot active catalyst, for the purpose of illustration and description a cracking catalyst having reforming characteristics, flows as a compact column along conduits 214 and 244 to reactors 215 and 246 respectively. The hot active catalyst flows downwardly as u substtur tially compact column through both reactors 21S and 246 counter'current to vaporous reactant flowing upwardly.

The catalyst flows downwardly in reforming zone 216 of reactor 215 Where the temperature of the catalyst is about 825 to about 1025 F. and preferably about 875 to about 950 F.

In order to obtain a reforming reaction. the space w:- locity of the vaporous reactant entering reforming zones 216 and 263 is about 1.0 to about 3.0 preferably ab t 1.5 to about 2.0 and the catalyst-to-liquid reactant wei h ratio is about 4 to about 8 and preferably about 4 to about 6.

The total catalyst in reforming zone 216 passes through seal legs 262 into desulfurizing zone 217 wherein the space velocity is about .25 to about 1.0 and preferably about .5 to about .75 and the catalyst-to-liquid reactant weight ratio is about 1 to about 4 and preferably about 1.5 to about 2.0. Under these conditions, the Ali (11 reaction temperature in desulfurizing zone 217' is about 650 to about 850 F. and preferably about 700 in about 800 F.

The total catalyst flowing into reforming zone 2.63 flows downwardly as a substantially compact column through reforming zone 263 of reactor 246 to leave the reactor via conduit 247 and chute 255 to a catalyst tram;- fer means.

The total catalyst flowing through zone 217 icavcs rcactor 215 by conduit 219 and thence along chute to any suitable catalyst transfer means whereby the den vated catalyst is transferred to a regenerator or kiln it h as kiln 25 of Figure 1. Such a catalyst transfe" Fil llllw can be an elevator, gas-lift or the like.

The catalyst from both reactors 215 and 246 is trans ferred by a suitable catalyst transfer means, not shown, to a regenerator, not shown, reactivated and return :t! to feed bin 211 in any suitable manner.

A mixture of hydrocarbons suitable for reforming and requiring desulfurizing, such as a mixture of hydrocarbons capable of isomerization and/or dehydrogenation and/or dehydrocyclization, for example-a virgin naphtha, is drawn from a source, not shown, through line 230, heated in furnace 231 and the heated oil discharged into desulfurizing zone 217 of reactor 215 through line 232 and associated distributor 266 under control of valve 235.

Distributor 266 is of any suitable type whereby the heated reactant, naphtha, can be distributed over the cross-section of desulfurizing zone 217.

The naphtha is heated to a temperature of about 650 to about 850 F. and preferably to about 700 to about 800 F. in furnace 231 and enters desulfurizing zone 217 at about the temperature at which it leaves furnace 231.

The heated naphtha flows upwardly counter-current to the downwardly flowing substantially compact column of catalyst at a catalyst-to-oil weight ratio of about 1.0 to about 4.0 and preferably about 1.5 to about 2.0 and at a space velocity of about 0.25 to about 1.0 and preferably of about 0.50 to about 0.75. During contact with the catalyst at an average temperature of about 650 to about 850 F. and preferably about 700 to about 800 F. produced by correlation of catalyst temperature, naphthe temperature, catalyst-to-naphtha weight ratio and space velocity, the naphtha is at least partially desulfurized.

The desulfurized naphtha leaves desulfurizing zone 217 by line 248. When the entire effluent from desulfurizing zone 217 can be adequately treated in reforming zone 216, the entire effluent passes through lines 248 and 249 (with valve 251 closed) to distributor 256 which is of any suitable type whereby the effiuent can be distributed over the cross-section of reforming zone 216.

When the entire eflluent from desulfurizing zone 217 cannot be adequately treated in reforming zone 216, a portion is diverted through valve 251 and line 250 to reforming zone 263 of reactor 246. When the quantity so diverted is insufiicient to be efiiciently reformed in reforming zone 263 additional low sulphur naphtha such as a cracked naphtha can be drawn from a source not shown through line 258 heated to a reforming temperature in furnace 259, discharged therefrom through line 260 under control of valve 261 into distributor 257 where it is mixed with the portion of effluent from desulfurizing zone 217 which enters distributor 257 from line 250.

The efiluent from desulfurizing zone 217 is introduced into reforming zone 216 and the etlluent or effluent and additional naphtha is introduced into reforming zone 263 at a rate such that the catalyst-to-naphtha ratio is about 4 to about 8 and preferably about 4 to about 6 and the space velocity is about 1.0 to about 3.0 and preferably about 1.5 to about 2.0.

The vaporous reactants flow upwardly from distributors 256 and 257 through reforming zones 216 and 263 counter-current to a downwardly flowing substantially compact column of catalyst in each reforming zone.

The effiuent from reforming zone 216 passes through line 238 to line 254. The effluent from reforming zone 263 passes through line 252 to line 254. The mixed effluents then pass through cooler 239 and line 240 to after-treatment, stabilization and fractionation.

When the capacity of reforming zone 216 is such as to adequately treat the total effluent from desulfurizing zone 217 and reactor 246 is not in operation valve 253 is closed.

When it is desired or necessary, both reactions can be carried out in the presence of a gas. Thus, for example, the desulfurizing can be carried out in the presence of hydrogen or a hydrogen-containing gas. Similarly, the reforming reaction can be carried out in the presence of hydrogen or a hydrogen-containing gas. Furthermore, for some purposes it can be desirable to supply heat to either or both zones by means of a gaseous or vaporous carrier. For such purposes, a suitable gas can be drawn from a source not shown through pipe 233 and passed into pipe 232 under control of valve 236 and thence into desulfurizing zone 217. Similarly, a gas can be passed from pipe 233 through pipe 234 under control of valve 237 to reforming zone 216. Likewise, a gas can be passed from pipe 233 through pipe 264 under control of valve 265 into reforming zone 263.

Thus, for example, in accordance with the principles of the present invention, a blend of 50 volume percent coker gasoline and 50 volume percent straight run heavy naphtha having a boiling range of 128 to 433 F. was treated as described hereinbefore. The effluent of the desulfurizing zone at various desulfurizing temperatures produced with an oil inlet temperature of 629 to 962 F. at the space velocities indicated was obtained in yields noted and with the sulfur content and octane numbers listed in Table I.

TABLE I Run No l I 2 F 3 4 1 5 0 Average Desulfurizing Ternperature, "F 929 825 765 1500 972 097 Sulfur percent Weight, Desul- Iurizing Zone Effluent. 0. 18 0. l7 0. 17 0. 21 0.26 0. 29 Yield of Er'fiuent, percent volume 77.9 93 95 77. 8 82. 3 Space Velocity.... 0. 5 0. 5 0.5 0.5 0. 1 2. 0 Catalyst-to-nnphtha w lght ratio 4.1 4. 2 4. 2 4.8 4.1 4.2 Octane number or Effluent I from Desulfurizing zone 75. 0 69 61. 5 (i0 74. 8 74. 6 Octance number of Eifiuent 3 cc. TEL... S6. 4 81 75. 5 74. 5 86. 0 85. 0 Percent Sulfur Rcmovcd.. 66 68 68 00 51 45 Sulfur content of fee-.l-tddesulfurizing zone 0.53 Weight percent. Research octane rat'mg of the feed was 01.5 clear and 72.0 with 3 cc. TEL.

I Research.

2 Research +3 cc. TEL.

It will be noted that runs numbers 2, 3 and 4 were made at desulfurization temperatures of 690 to 825 F. and at relatively low space velocities while runs Nos. 1, 5 and 6 were made at desulfurization temperatures in excess of 900" F. at space velocities of 0.5, 1.0 and 2.0. Nevertheless, the yield of desulfurized oil of comparable grade was far greater, i. e., in excess of 90 volume percent in the runs made at low temperatures and low space velocities than the yield of desulfurized oil in the runs made at high temperatures and low space velocities or high temperatures and high space velocities. Accordingly, it is preferred to operate at temperatures of about 700 to about 800 F. in the desulfurizing zone.

When the afore-described efiluents are then reformed as described hereinbefore, the finished products are obtained in the yields and with the octane numbers indicated in Table II.

TABLE II Run No. 4 Average reforming temperature F 970 Yield reformate, volume percent on charge of desulfurizing zone eflluent 80.0 Space velocity 1.5 Catalyst-to-oil weight ratio 4.5 Octane number of reformate 1 75.0 Octane number of reformate+3 cc. TEL 87.0

1 Research. Research +3 cc. TEL.

Those skilled in the art will understand that the auxiliary reforming zone 263 can have a capacity just sufficient to treat the portion of efliuent from desulfurizing zone 217 in excess of that which can be treated in reforming zone 216 or reforming zone 263 can have a capacity such as to treat an additional low sulfur naphtha or the like as well as or simultaneously with the efiluent from desulfurizing zone in excess of that which can be treated in reforming zone 217.

In view of the foregoing description and discussion, it is believed apparent to those skilled in the art that the present invention provides a means for carrying out a plurality of reactions at different reaction conditions of temperature and residence time in a plurality of zones in a reactor through which a single catalyst or a mixture of catalysts flows successively as a substantially compact column and that the reaction condition in the difierent zones are controlled, regulated and maintained by controlling the catalyst-to-reactant weight ratio, the space velocity and correlating the aforesaid with the catalyst and reactant temperatures to provide different reaction temperatures in each zone. Specifically, the present invention provides for desulfurizing and reforming a mixture of hydrocarbons under relatively severe reforming conditions in one zone and desulfurizing the same mixture of hydrocarbons under relatively less severe conditions in a second zone by controlling, regulating and maintaining a different catalyst-to-reactant weight ratio and a different space velocity in each zone. Thus, for example, a reforming catalyst, for example, a chromiaalumina or a molybdena-alumina reforming catalyst, can be used at reforming temperatures and pressures of about 850-l080 F., preferably about 875 to 1060 F., and about 25600, preferably about 100 to 300 p. s. i. a. in the presence of about l-l5, preferably about 4-10 mols of recycle gas per mol of naphtha or about l-8, preferably about 25 mols of hydrogen at a space velocity of about 0.1-6.0, preferably about 0.5-2.0, volumes of liquid charge stock per volume of catalyst in the reforming zone. The charge stock is desulfurized at a temperature of about 650-850 F., preferably about 700 to about 800 F. in the presence of the reforming catalyst used in the reforming zone.

ltclaim:

l. A process for desulfurizing and reforming a hydrocarbon mixture in a single multi-zone reactor which comprises introducing active particle-form catalyst, said catalyst combining activity for reforming with activity for hydrogenation of organically combined sulfur in a hydrocarbon mixture to hydrogen sulfide, at a temperature of about 950 F. to about ll F. into a single multi-zone reactor. flowing said catalyst through a reforming zone, flowing a portion of said catalyst from said reforming zone to and through a by-pass zone. flowing the balance of said catalyst through a desulfurization zone, introducing a hydrocarbon mixture to be desulfurized and reformed into said desulfurization zone at a temperature of about 650 F. to about 850 F., flowing said hydrocarbon mixture at a liquid space velocity of about 0.25-l .0 v./v./hr. through said desulfurization zone in contact with said balance of said catalyst to at least partially desulfurize said hydrocarbon mixture and to lay down a carbonaceous deposit on said catalyst, flowing at least partially desulfurized hydrocarbon mixture from said desulfurizing zone into and through said reforming zone at a space velocity of about l.03.0 v./v./ hr. in contact with said catalyst to reform said at least partially desulfurized hydrocarbon mixture and to lay down a carbonaceous deposit on said catalyst, withdrawing reformed and desulfurized hydrocarbon mixture from said reforming zone, withdrawing catalyst contaminated with carbonaceous deposit from said (lesulfurizing zone and from said by-pass zone, regenerating and heating said withdrawn catalyst to a temperature of about 950 F. to about ll00 F. by combustion of said carbonaceous deposit, regulating the flow of catalyst and at least partially desulfurized hydrocarbon mixture through said reforming zone to provide a catalyst to oil ratio of about 4 to 8 to maintain a reaction temperature of about 825 F. to about 1025 F. in said reforming zone, and regulating the flow of catalyst and hydrocarbon mixture through said dcsulfurizing zone to provide a catalyst to oil ratio differout to the aforesaid catalyst to oil ratio and about 1 to 4 to maintain a reaction temperature of about 650 F. to about 850 F. in said desulfurizing zone.

3. A process for catalytically cracking and desulfuriziug a hydrocarbon mixture in a single multi-zone reactor which comprises introducing hot active particle form solid catalyst which combines activity for converting hydrocarbons boiling above the gasoline range into hydrocarbons boiling in the gasoline range with activity for hydrogenating organically combined sulfur in said hydrocarbon mixture to hydrogen sulfide at a temperature of about 975 F. to about 1075 F. into a multi-zone reactor, flowing a portion of said catalyst through a by-pass zone, flowing the balance of said catalyst through a desulfurizing zone, flowing a stream of catalyst from said by-pass zone, flowing a stream of catalyst from said desulfurizing zone, combining said flowing streams of catalyst, introducing said combined flowing streams of catalyst into a catalytic cracking zone, introducing hydrocarbon mixture to be desulfurized and catalytically cracked into said desulfurizing zone at a temperature of about 650 F. to 850 F., flowing said hydrocarbon mixture at a liquid space velocity of about 0.25 to 1.0 v./v./hr. through said desulfurizing Zone in contact with said catalyst to produce an at least partially desulfurized hydrocarbon mixture and to lay down a carbonaceous deposit on said catalyst, flowing said at least partially desulfurized hydrocarbon mixture through said cracking zone at a liquid space velocity of about 0.5 to 4.0 v./v./hr. to produce a catalytically cracked and at least partially desulfurized hydrocarbon mixture and to deposit on said catalyst at carbonaceous deposit, withdrawing cracked and at least partially desulfurized hydrocarbon mixture from said catalytic cracking zone, withdrawing catalyst con taminated with carbonaceous deposit from said catalytic cracking zone, regenerating and heating said catalyst to a temperature of at least about 975 F. to about 1075 F. by combustion of said carbonaceous deposit, regulating the flow of said balance of catalyst through said desulfurizing zone to provide a catalyst to oil ratio of about 1 to 4 to maintain said desulfurizing zone reaction temperature at about 650 to about 850 F. and regulating the flow of the combined streams of catalyst from desulfurizing zone and said by-pass zone through said cracking zone to provide a catalyst to oil ratio different to the aforesaid catalyst to oil ratio and about 4 to 8 to maintain said cracking zone reaction temperature.

3 A process for reforming and desulfurizing a hydrocarbon mixture which comprises introducing active particleforrn solid catalyst at a temperature of about 825 F. to about l075 F. into two reforming zones A and B, said catalyst combining activity for reforming hydrocarborn with activity for hydrogenating organically combined sulfur in a hydrocarbon mixture to hydrogen sulfide, flowing said catalyst through said reforming zones, flowing catalyst from said reforming zone A only into and through a desulfurizing zone, introducing a hydrocarbon mixture at about 650 to about 850 F. into said desulfurizing zone, flowing said hydrocarbon mixture through said desulfurizing zone in contact with said catalyst to provide an at least partially desulfurized hydrocarbon mixture and to produce a carbonaceous deposit on said catalyst, regulating the flow of said hydrocarbon mixture through said desulfurizing zone to provide a liquid space velocity of 0.25 to l .0 v./v./hr. and to provide a catalyst to oil ratio of about l-4 to maintain a reaction temperature of about 650 F. to about 850 F, introducing said at least partially desulfurized hydrocarbon mixture into said reforming zones A and B, proportioning the feed of at least partially desulfurized hydrocarbon mixture to said reforming zones A and B to provide a liquid space velocity of about 1 to about 3 v./v./hr. in each of said reforming zones while providing a catalyst to oil ratio in each of said zones A and B different to the aforesaid catalyst to oil ratio and about 4 to about 8 to maintain a reaction temperature of about 825 to about l025 H. flowing said partially desulfurizcd hydrocarbon mixture through said reforming zones in contact with said catalyst to produce a reformed desulfurized hydrocarbon mixture and to produce a carbonaceous deposit on said catalyst, withdrawing reformed desulfurized hydrocarbon mixture from said reforming zones, withdrawing catalyst contaminated with carbonaceous deposit from said reforming zone B, withdrawing catalyst contaminated with carbonaceous deposit from said desulfurizing zone,

13 combining said withdrawn catalyst, regenerating and heating said catalyst to a temperature of about 825 F. to about 1075 F. by combustion of said carbonaceous deposit, and recycling said heated catalyst to said reforming zones.

4. In the method for subjecting hydrocarbon mixtures to at least two different conversions in a plurality of reaction zones, one of said reaction zones being at a higher temperature than the other which comprises introducing a given quantity particle-form catalytic material catalyzing the reaction in all reaction zones at at least said higher temperature into one of a plurality of reaction zones, flowing said given quantity of particle-form catalytic material through all of said reaction zones, contacting all of said given quantity of particle-form catalytic material with reactant in each of said reaction zones, regulating the fiow of reactant to each of said reaction zones and regulating said given quantity of particle-form catalytic material to establish relatively mild reaction conditions in one of said reaction zones and relatively severe reaction conditions in the others of said reaction zones, the improvement which comprises contacting only a part of said given quantity of pm'ticle-form catalytic material with reactant in the reaction zone under relatively mild reaction conditions.

5. The improvement in the process of claim 4 wherein the reactant contacts only about 60 to about 80 percent of the given quantity of catalytic material in the zone under relatively mild reaction conditions.

References Cited in the tile of this patent UNiTED STATES PATENTS 2,417,308 Lee Mar. ll, 1947 2,418,672 Sinclair et a1 Apr. 8, 1947 2,418,673 Sinclair et all. Apr. 8, i947 2,437,222 Crowley et al Mar. 2, 1948 2,439,730 Happel Apr. 13. 194R 2,642,38l Dickinson June 16, i953 2,692,903 Haehmuth Oct. 26, 1954 2,724,683 Nadro Nov. 22, 1955

Claims (1)

1. 2. A PROCESS FOR CATALYTICALLY CRACKING AND DESULFURIZING A HYDROCARBON MIXTURE IN A SINGLE MULTI-ZONE REACTOR WHICH COMPRISES INTRODUCING HOT ACTIVE PARTICLE FORM SOLID CATALYST WHICH COMBINES ACTIVITY FOR CONVERTING HYDROCARBONS BOILING ABOVE THE GASOLINE RANGE INTO HYDROCARBONS BOILING IN THE GASOLINE RANGE WITH ACTIVITY FOR HYDROGENATING ORGANICALLY COMBINED SULFUR IN SAID HYDROCARBON MIXTURE TO HYDROGEN SULFIDE AT A TEMPERATURE OF ABOUT 975*F. TO ABOUT 1075*F. INTO A MULTI-ZONE REACTOR, FLOWING A PORTION OF SAID CATALYST THROUGH A BY-PASS ZONE, FLOWING THE BALANCE OF SAID CATALYST THROUGH A DESULFURIZING ZONE, FLOWING A STREAM OF CATALYST FROM SAID BY-PASS ZONE, FLOWING A STREAM OF CATALYST FROM SAID DESULFURIZING ZONE, COMBINING SAID FLOWING STREAMS OF CATALYST, INTRODUCING SAID COMBINED FLOWING STREAMS OF CATALYST INTO A CATALYST CRACKING ZONE, INTRODUCING HYDROCARBON MIXTURE TO BE DESULFURIZED AND CATALYTICALLY CRACKED INTO SAID DESULFURIZING ZONE AT A TEMPERATURE OF ABOUT 650*F. TO 850*F., FLOWING SAID HYDROCARBON MIXTURE AT A LIQUID SPACE VELOCITY OF ABOUT 0.25 TO 1.0 V./V./HR. THROUGH SAID DESULFURIZING ZONE IN CONTACT WITH SAID CATALYST TO PRODUCT AN AT LEAST PARTIALLY DESULFURIZED HYDROCARBON MIXTURE AND TO LAY DOWN A CARBONACEOUS DEPOSITE ON SAID CATALYST, FLOWING SAID AT LEAST PARTIALLY DE-

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