BE516290A - - Google Patents

Description

       

   <Desc / Clms Page number 1>
 



  IMPROVEMENTS IN THE OPERATION CALLED HYDROFORMING.



   The present invention relates to the catalytic conversion of hydrocarbon fractions boiling in the boiling range of low detonating power engine fuels, into engine fuels rich in aromatics and of high octane number; the invention relates especially to a process by which such conversion is carried out by the technique of fluidized solids.



   The hydroforming operation is a well-known and widely used process for the treatment of hydrocarbon fractions boiling in the boiling range of naphtha or engine fuels, with a view to improving said fractions from a quality point of view. or to increase their aromaticity, and to improve the anti-knock characteristics of said hydrocarbon fractions. By hydroforming is meant an operation carried out at elevated temperatures and pressures in the presence of solid catalyst particles and hydrogen, whereby the hydrocarbon fraction is improved as regards its aromaticity, and in which it is not there is no net consumption of hydrogen.

   Hydroforming operations are ordinarily carried out in the presence of hydrogen or a hydrogen-rich recycle gas, at temperatures of 750-1150 F, at a pressure of the order of about 50 to 1000 pounds per hour. square inch, and in contact with catalysts such as molybdenum oxide, chromium oxide, or, in general, oxides or sulphides of metals of Groups IV, V, VI, VII and VIII of periodic system, used alone or generally supported on a base or spacer, such as alumina gel, precipitated alumina, or zinc aluminate spinels.

   A good hydroforming catalyst is a catalyst containing about 10% by weight of molybdenum oxide on an aluminum oxide basis, prepared in. heat treating hydrated aluminum oxide, or on zinc aluminate spinels.

 <Desc / Clms Page number 2>

 



   It has been proposed to carry out the hydroforming of naphtha fractions in a fluidized solids reactor system, in which naphtha vapors pass continuously through a dense fluidized bed of hydroforming catalyst particles, located in a zone. Reaction The spent catalyst particles are removed from the dense bed of the reaction zone and are sent to a separate regeneration zone, in which carbonaceous deposits rendering the catalyst inactive are removed by combustion, the regenerated catalyst particles being returned then to the main reaction vessel or hydroforming reaction zone.

   The fluid hydroforming operation thus carried out has several fundamental advantages over the fixed bed hydroforming operation, such as: (1) the operations are continuous, (2) the containers and the installation. can be designed for one rather than two functions, (3) the temperature of the reaction apparatus is substantially constant throughout the bed, and (4) regeneration or reconditioning of the catalyst can be readily rule.



   A particular advantage of the above fluidized solids operation is that the freshly regenerated catalyst can be used to transport some of the heat required for the hydroforming reaction from the regeneration zone to the regeneration zone. the reaction zone, It has been proposed, for this purpose, to discharge freshly regenerated, hot catalyst particles from a down pipe of the regenerator, into a stream of hot recycle gas, rich in hydrogen, located in a transfer line, whereby the catalyst particles are subjected to a reconditioning treatment comprising at least partial reduction of the oxides of higher catalytic metals formed during the regeneration,

   in a lower or more catalytically active form of the catalytic metal oxides, during their passage through the transfer line into the reaction zone. Due to the high temperature of the regenerated catalyst (1050 -1300 F) and the exothermic character of the reaction between the hot, freshly regenerated catalyst and the hydrogen, it is necessary to carry out the low transfer line. diameter and short, in order to maintain the contact time of the catalyst and the hydrogen-containing gas, short enough to avoid over-treatment and / or thermal degradation of the catalyst.

   It has also been proposed to cool the freshly regenerated catalyst, by direct or indirect heat transfer with recycle catalyst from the reactor, in order to achieve better control of the pretreatment while still using the sensible heat transported. by the regenerated catalyst to the reaction side of the system.



   The object of the present invention is to provide a novel method of operating a fluidized solids hydroforming system.



   It is still an object of the invention to provide a method of operating a fluidized solids hydroforming system which eliminates the need to subject the freshly generated hydroforming catalyst to any treatment with water. hydrogen or a gas rich in hydrogen, before the introduction of said freshly regenerated catalyst into the hydroforming reaction zone.



   These and other objects will appear more clearly from the detailed description and the following claims.



     It has now been found that it is possible in fluid-type hydroforming operations to add the freshly regenerated catalyst directly to the hydroforming reaction zone without treatment with hydroforming. drogen or a hydrogen-rich gas, even when a substantially complete removal of carbon from the catalyst is carried out in the regenerator, i.e. up to less than 0.2% by weight, preferably less than 0 , 1% by weight of carbon on the catalyst, provided that the catalyst / oil ratio is low (less than about 1.5) and provided that the regenerated catalyst particles are substantially free of carbon monoxide,

   carbon dioxide and oxygen. At low catalyst / oil ratios, the amount of carbon

 <Desc / Clms Page number 3>

 Freshly regenerated analyzer added to the reactor fluid bed is small compared to the amount of reactor catalyst or equilibrium in the fluid bed. Due to the turbulent nature of the fluid bed of the reactor, the sensible heat of the thoroughly regenerated catalyst as well as the exothermic heat of reaction between the higher catalytic metal oxides in the freshly regenerated catalyst, and the hydrogen in the reaction mixture are quickly distributed over the reactor catalyst or equilibrium, thus avoiding overheating or thermal degradation of the catalyst.



   In addition, the reaction or reduction of the thoroughly regenerated catalyst is relatively fast even at reactor temperature conditions, and therefore only a small portion of the feed passes over unreduced catalyst.



   Reference is now made to the accompanying drawings.



   Figure 1 is a schematic view of a reactor-regenerator system according to the present invention.



   Figure 2 is a modified schematic view in which the regenerator is disposed above the reactor, and the regenerated catalyst descent line extends downwardly through the dense bed of the reactor.



   Referring to Figure 1, 10 denotes a reaction vessel having at its base an inlet pipe 11 for the introduction of a recycle gas or rich in hydrogen, and which is hot. A perforated plate or grid 12 is disposed horizontally in the lower part of the reaction vessel, in order to ensure a uniform distribution or distribution of the incoming gas, following the entire cross section of the reaction vessel. A separate inlet line 13 serves for the introduction of a naphtha feed, above the grate 12, although the naphtha feed can, if desired, be introduced separately or with a gas. recycling or rich in hydrogen, below the grid 12.

   The reaction vessel 10 is charged with finely subdivided hydroforming catalyst particles, and the surface velocity of the rising vapors and gases through the reactor is controlled to form a turbulent, fluidized, dense bed of catalyst 14, having a determined level L surmounted by a dilute or dispersed phase 15 comprising a small amount of catalyst, entrained in the vaporous reaction products. The reaction products are removed at the top of the reactor 10 after passing through a cyclone separator 16 or similar device for the separation of the entrained catalyst particles. Entrained catalyst particles are returned to dense bed 14 through an extension line attached to the bottom of the cyclone separator.

   The reaction products, essentially free of catalyst particles, pass from the cyclonic separator 16 into an outlet line 17 for the product, leading to a suitable fractionation and / or storage facility.



   The catalyst particles are continuously removed from the dense bed 14 through the spent catalyst removal line 18 to an outer cleaning vessel 19. It should be understood that said cleaning or cleaning vessel. The finishing could also be disposed in the reaction vessel, such as, for example, by providing a vertical duct or compartment, preferably extending above level L and provided with an orifice or lumen to regulate the discharge of the catalyst outside the dense bed.

   A branch 20 is provided near the bottom of the cleaning device for the introduction of a suitable cleaning gas, such as steam, nitrogen, purified flue gas, etc., which will serve to remove hydrocarbons. entrained or adsorbed res or hydrogen, which would otherwise be carried to the regeneration zone and burnt there.

   The cleaning gas and the cleaned gases and vapors are removed at the top of the device 19 and sent through a line 21 to the upper part of the reactor 10, in the event that large quantities of catalyst are entrained and a recovery of these in the cyclone separator 16 of the reactor is desired; or else said gases are sent via a pipe 22 into the outlet pipe 17 of the product, in the case where it is desired that the cleaning gases and: or

 <Desc / Clms Page number 4>

 spent catalyst which has been in contact with the cleaning gases does not pass through the reactor.

   The lower end of device 19 is connected at 23 to conduit 24 and forms with it a vertical pipe to develop sufficient fluid-static pressure to facilitate the transfer of spent catalyst to the regenerator side of the system. A distributor spool 25 or the like is provided near the base of conduit 24 for controlling the discharge of spent catalyst into transfer conduit 26. Usually, a sufficient amount of gas is entrained by the catalyst. - passing through line 24 to maintain said catalyst in a fluidized or free-flowing state. If desired, however, one or more gas branches may be provided along line 24 to supply liquefying gas thereto.



   The cleaned spent catalyst is discharged from the base of the riser into a transfer line 26, where it is picked up by a stream of air or regeneration gas supplied through line 27. air transports the particles of spent catalyst in the form of a dilute slurry, through the transfer line 26 and the riser 28 to bring it to the bottom of the regeneration vessel 30. A perforated plate or distribution grid 29 is disposed near the bottom of regenerator 30 to ensure a uniform distribution of incoming catalyst and air across the entire cross section of the regenerator.

   Due to the rate at which carbonaceous deposits are burnt off from the drhydroforming catalysts under high reaction pressures, only a portion, preferably not more than 40%, of the catalyst should be used. air required for regeneration, to transport spent catalyst through transfer line 26 and riser 28, and to add the remainder of air required for regeneration through a separate line 31, or additional lines discharging directly into the regeneration vessel.



   As at the preferred low catalyst flow rates, there is more heat liberated by burning off the carbonaceous catalyst deposits in the regenerator than can be returned to the reactor by the circulating catalyst, which is necessary for most purposes. feedstocks being treated, to provide cooling coils 46 through which water entering through 46a can flow to give steam at 46b, or feed can be pumped through these coils to provide steam. perform preheating.



   The superficial velocity of the regeneration gases through the vessel 30 is controlled so as to form a turbulent, fluidized, dense bed 32 of catalyst particles and gas, having a determined level L ', which is surmounted by a phase. diluted or dispersed 33 in the upper part of the. regenerator, phase which comprises small amounts of catalyst entrained in the regeneration gases. Regeneration gases are removed at the top of the regenerator, preferably after passing through a cyclone separator 34 or similar device which serves to remove most of the catalyst particles from the regenerator gases. The separated catalyst particles are returned to dense bed 32 through a dip line attached to the bottom of the cyclone separator.

   Regeneration gases are discharged from the cyclone separator 34 into the outlet line 35 and through a pressure regulating valve 36 to a waste gas stack or to a suitable storage facility, if applicable. wants to use gas. regeneration for cleaning or purification purposes.



   The operation of the regenerator is regulated by admitting a small excess of oxygen in the outlet gases. The air valve is adjusted so that the desired excess oxygen is maintained, thereby ensuring that substantially all of the deposited carbon is removed from the catalyst by burning. This results in the carbon content being less than 0. 2% by weight on the regenerated catalyst. Complete regeneration is further evidenced by substantially complete oxidation of the catalytic metal to the hexavalent form.

   For example, in a fluid hydroforming operation using

 <Desc / Clms Page number 5>

 a molybdenum oxide catalyst, analysis of the reactor catalyst in equilibrium indicates that the molybdenum is essentially in the five-valent form, the average valence value being generally in the range of 4.7 to
5.0, the last digit corresponding to the valence of molybdenum in the compound Mo2O5. In full regeneration, molybdenum is converted essentially to the hexavalent form or to MoO3, analysis of the fully regenerated catalyst showing that the average valance value of the complete catalyst. completely regenerated is of the order of 5.7 to 6.0.



   A wall 37 is disposed in the regenerator and forms with the inner wall thereof a cleaning or scrubbing space or compartment 38. The wall 37 extends above the level L 'of the dense bed, and an orifice or lumen of limited size is provided to regulate the flow of regenerated catalyst into this cleaning compartment. This can be provided outside the regenerator, in a similar manner to the arrangement of the device 19 for cleaning the spent catalyst, relative to the reactor 10, or the wall 37 could end at or below the level. L 'of the dense bed, in which case the catalyst would overflow from dense bed 32 into compartment 38.

   A cleaning or scrubbing gas, such as air, nitrogen, etc., is introduced into compartment 38 through an inlet line 40 in order to remove entrained or adsorbed gaseous materials. The purified catalyst passes from the base of compartment 38 into a transfer line 41, where small amounts of nitrogen can be added as a purge to release the regenerated catalyst from carbon oxides and oxygen, after which the particles. of regenerated and purified catalyst is discharged by a distributor 43, through the side wall of the reactor 10, directly into the dense bed 14 thereof.

   If desired, a baffle element 44 may be provided on the inner wall of reactor 10, below the discharge end of conduit 41, to deflect upward gases and vapors and prevent their entry into. line 41 where they would interfere with the flow of catalyst and possibly react with the regenerated catalyst, while eventually escaping into the regenerator, where they would be burnt. The regenerated catalyst is discharged at substantially the temperature of the regenerator through the transfer line 41.

   The catalyst particles in the dense reactor bed 14 are rapidly set in turbulent and rapid motion, and the dense reactor bed constitutes an extremely large amount of catalyst, compared to the amount of hot, freshly regenerated catalyst. a joust. As a result, the stream of hot, freshly regenerated, unpretreated catalyst particles and sensible heat carried by said particles are rapidly dispersed or dissipated in the dense bed 14 of the reactor. In addition, any heat generated by the reaction between the hydrogen in the reaction mixture and the higher catalytic metal oxides formed during regeneration is also rapidly dissipated throughout the bed.



   In the embodiment shown in FIG. 2, 110 denotes a reaction vessel provided at its base with an inlet pipe III for the introduction of hot, hydrogen-rich or recycle gas. A perforated plate or grid 112 is disposed horizontally in the lower portion of the reaction vessel to ensure a uniform distribution of the incoming gas along the entire cross section of the reaction vessel. A separate inlet line 113 is provided for the introduction of the naphtha feed, above the grate 112, although said feed can, if desired, be introduced separately or at the same time as the gas. recycling or rich in hydrogen, below the grid 112.

   The reaction vessel 110 is charged with finely subdivided hydroforming catalyst particles, and the surface velocity of the rising vapors and gases in the reactor is controlled to form a dense fluidized turbulent bed of catalyst 114, having a level. determined L, topped with a dilute or dispersed phase 115, comprising a small amount of catalyst entrained in the vaporous reaction products. The reaction products are removed at the top of reactor 110 by passing through a separator.

 <Desc / Clms Page number 6>

 Cyclone rator 116 or similar device for separating entrained catalyst particles. The entrained catalyst particles are returned to dense bed 114 through a dip line attached to the base of the cyclone separator.

   The reaction products, substantially liberated from the catalyst particles, pass from the cyclone separator 116 into the product outlet line 117 leading to a suitable fractionation and / or storage facility.



   The catalyst particles are continuously removed from the dense bed 114 through a spent catalyst removal line 118 to an outer cleaning vessel 119. It should be understood that the cleaning device could still be disposed in the reaction vessel, such as, for example, by providing a vertical duct or compartment, preferably extending above level L and provided with orifices or lumens to control the discharge of the catalyst from the intended bed to the cleaning compartment or duct.

   A branch 120 is provided near the bottom of device 119 for the introduction of a suitable cleaning or scrubbing gas, such as steam, nitrogen, flue gas, etc., which will serve to remove. entrained or adsorbed hydrogen or hydrocarbons which would otherwise be carried to the regeneration zone and burnt there.

   The purifying gas and the purified gases and vapors are removed at the top of the device 119, and sent through a line 121 to the upper part of the reactor 110 in the event that large quantities of catalyst are entrained and a recovery of this catalyst in the cyclone separator 116 of the reactor is desired, or these gases are sent through the line 122 into the outlet line 117 of the product, in the case where it is desired that the scrubbing gas and / or the catalyst depleted that has been in contact with the scrubbing gas does not pass through the reactor.



  The lower end of the device 119 is connected at 123 to the conduit 124 and forms therewith a vertical line for the development of sufficient fluid-static pressure to facilitate the transfer of the spent catalyst to the regeneration side of the cylinder. system. A distributor spool 125 or the like is provided near the base of conduit 124 for controlling the discharge of spent catalyst into transfer conduit 126.



  Ordinarily, a sufficient amount of gas is entrained with the catalyst passing through line 124 to maintain it in a free flowing or fluidized state. If desired, however, one or more gas branches may be provided along conduit 124 to supply fluidizing gas thereto.



   The stripped spent catalyst is discharged from the base of riser 124 into transfer line 126 where it is picked up by a stream of regeneration gas or air. The air stream carries particles of spent catalyst as a dilute slurry through transfer line 126 and riser of spent catalyst 128 to the bottom of regeneration vessel 130. A perforated plate or distribution grid 129 is disposed near the bottom of regenerator 130 to ensure a uniform distribution of incoming catalyst and air along the entire cross section of the regenerator.

   In view of the speed at which carbonaceous deposits are removed by burning, hydroforming catalysts, under high reaction pressures, only a portion, preferably no more than 40%, should be used. air required for regeneration to transport spent catalyst through transfer line 126 and riser 128, and to add the remainder of air required for regeneration through a separate line 131 or additional lines discharging directly into the regeneration vessel.



   The superficial velocity of the regeneration gases through the vessel 130 is controlled so as to form a turbulent, fluidized, dense bed 132 of catalyst particles and gas, having a determined level L 'which is surmounted by a phase. diluted or dispersed 133 in the upper part of the regenerator, comprising small amounts of catalyst entrained in the regeneration gases. These are removed at the top of the regenerator, from

 <Desc / Clms Page number 7>

 preferably after passing through a cyclone separator 134 or similar device, which serves to remove most of the catalyst particles from the gas. The separated catalyst particles return to the dense bed
132 by a dip pipe attached to the bottom of the cyclone separator.

   Regeneration gases are discharged from the cyclone separator 134 through an outlet line 135 and through a pressure regulating valve 136 to a waste gas stack or to a suitable washing facility. or storage, in the case where it is desired to use the regeneration gases for purifying or cleaning purposes.



   A vertical, open-ended conduit 137 is disposed in the regenerator with its upper end open at level L 'of the dense bed for the removal of the regenerated catalyst. The catalyst overflows the top of conduit 137 and either flows over the inner wall thereof or falls freely downward for some distance. A scrubbing or cleaning gas, preferably air or an inert gas, such as nitrogen or flue gas, is introduced into line 137 through inlet line 138. The air is the preferred scrubbing gas because it performs a final cleaning of the regenerated catalyst and effectively frees the latter of CO 2 and CO.

   A dense column of catalyst forms in line 137 generally from a level a short distance above the scrub gas inlet 138, the height of the dense catalyst column being sufficient. to develop a fluid-static pressure at the bottom 139 of the conduit 137, pressure which will be sufficient to force the regenerated catalyst to flow from the base of the conduit 137 into the dense bed 114 of the reactor 110.



  Small amounts of an inert gas, such as nitrogen or flue gas which has been liberated from carbon oxides, are introduced into line 137 through inlet line 140. The amount of gas thus introduced is so low that it is economically feasible to use nitrogen or flue gas which has been stripped of oxides of carbon and oxygen. A conical element 141, forming a baffle, is arranged just below the lower end 139 of the duct 137, in order to prevent gases or vapors which rise through the bed 114, from entering the duct 137 and thwarting the flow of regenerated catalyst.

   The regenerated catalyst, in the vertical line 137, is in indirect heat exchange with the dense bed of the reactor during its passage from level L to point 139 where it is discharged, and, therefore, it is cooled to a temperature lower than that of the regenerator before discharging into the reactor bed.



  As the catalyst particles mix immediately with the dense bed 114 as they are discharged from the riser 137, they are therefore rapidly cooled to the temperature of the reactor bed. In addition, the heat generated by the action of hydrogen in the gaseous reaction mixture on the higher catalytic metal oxides formed during regeneration is rapidly dissipated throughout the dense bed.



  In this way, a reduction in the higher catalytic metal oxides formed during regeneration takes place directly in the reactor bed rather than in a separate pretreatment operation; at the same time, the danger of overtreatment, and detrimental thermal effects on the catalyst are avoided by the large fluidized bed of catalyst in the reactor.



   It is desirable to provide means for regulating the pressure of the regenerator. This can be done by providing a differential pressure monitor 143 which is actuated through suitably disposed secondary pressure lines, in the regenerator, reactor, and / or the regenerated catalyst riser; connections 144 and 145 are provided in the vertical pipe or conduit 137, and alternating pressure connections 146 and 147 are provided respectively in the dilute phase of the regenerator and in the dilute phase of the reactor.

   The controller 143 operates the valve 136 in the regenerator gas outlet line 135, in response to changes in pressure at the selected connections, to maintain the pressure difference substantially constant. For example, using branches 145 and 144, or maybe even branches 145 and 146, a single and very sensitive manometer tube,

 <Desc / Clms Page number 8>

 directly showing the pressure difference between the reactor and the regenerator, is available to operate the control valve 136.



  In the event that it is desired to minimize the contact of the water vapor formed during the reduction of the oxides of higher catalytic metals, with the reactor bed, the transfer pipe or vertical pipe 137 can terminate just below the level L in the reactor. reactor 110. In this case, it would be preferable to have the exhaust line 118 of the exhausted catalyst, in the lower part of the reactor.



   During the operation carried out according to the present invention, a substantially total regeneration of the catalyst is carried out. Due to the high rate of burning at high pressures, regeneration is completed within seconds. Complete regeneration is evidenced by the presence of excess or free oxygen in the flue gases escaping from the regenerator, and by the presence of less than 0.3% by weight of carbon on the gas. regenerated catalyst, and even in most cases less than about 0.1% by weight. Complete regeneration is further evidenced by substantially complete oxidation of the catalytic metal to the form having the highest valence.

   For example, in a fluid by-dorforming operation, in which molybdenum oxide is used as the catalyst, analysis of the catalyst of the equilibrium reactor shows that the molybdenum is essentially in the pentavalent form, the average valence value generally being of the order of 4.7 to 5.0, the last digit corresponding to the valence of molybdenum in the compound Mo05. In complete regeneration, molybdenum is converted to essentially the hexavalent form or MOO3, analysis of the fully regenerated catalyst showing that the average valence value of the fully regenerated catalyst is in the range of 5.7-6.0.



   The feedstock to the hydroforming reactor may be untreated naphtha, cracked naphtha, fischer-Tropsch naphtha, etc. The feedstock is preheated alone or in admixture with recirculation gas to the reaction temperature or to the maximum possible temperature, while avoiding thermal degradation of said feed.



  Ordinarily, the preheating of the feedstock is carried out to temperatures of about 800 to 1000 F, preferably about 950 F.



  The preheating of the naphtha should be as high as possible while avoiding thermal degradation of said naphtha such as, for example, by limiting the residence time in the furnace or in the feed transfer or inlet lines. The preheated feedstock can be supplied to the reaction vessel, in admixture with recycle gas, rich in hydrogen, or it can be introduced separately, as shown. Recycle gas, which contains about 50 to 80% er. volumes of hydrogen, is preheated to temperatures of about 1150 -1300 F before it is introduced into the inlet line 11.

   The preheating of the recycle gas depends on the heat requirements of the particular reactions, the upper temperature limit being set by the tendency of the hydrocarbon constituents to undergo thermal degradation. Recycle gas is introduced directly into the bottom of reaction vessel 10 and should flow through the reactor at a rate of about 1000 to 10,000 cubic feet per barrel of naphtha feed. Since compressors for the recycle gas constitute a significant expense in an installation of this type, it is advantageous to keep the amount of recycle gas to the minimum amount which will keep carbon formation within limits and, in particular, at the same time, will suffice to introduce the quantities of heat necessary for the reaction.



   The reactor system is loaded with a mass of finely subdivided hydrforming catalyst particles. Suitable catalysts include oxides of the Group VI metals, such as molybdenum oxide, chromium oxide or tungsten oxide, or mixtures of these oxides, disposed on a support such as activated alumina. , zinc aluminate spinels, etc. Preferred catalysts contain about 5 to 15 wt% molybdenum oxide or about 10 to 40 wt% molybdenum oxide.

 <Desc / Clms Page number 9>

 chrome, on a suitable support. If desired, small amounts of stabilizers and promoters, such as silica, calcium oxide, cerium oxide, or potassium hydroxide can be included in the formulation. catalyst.

   The catalyst particles are, for the most part, between 200 and 400 mesh sizes, or about 0-200 microns in diameter, with a major proportion being between 20 and 80 microns.



   The hydroforming reactor vessel should operate at temperatures between about 850 and 950 F, preferably about 900 F, and at pressures between about 50 and 500 pounds per square inch. Temperatures above 900 F result in increased carbon formation and less selectivity to gasoline fractions, while at temperatures below about 900 F the stringency of operation is low and therefore would require an extremely large reaction vessel.

   Ordinarily, lowering the reactor pressure below 200 pounds per square inch results in increased carbon formation, which becomes excessive, in most cases, at pressures below about 75 pounds per square inch. in the case of certain catalysts, such as molybdenum oxide on alumina.



  In the case of molybdenum or chromium oxide catalysts on zinc aluminate spinels, however, the optimum pressure appears to be about 50 pounds per square inch. Above 200 pounds, however, the selectivity of the catalyst for light products (C4 and lower) increases rapidly. The average residence time of the catalyst in the reactor is of the order of 3 to 4 hours. The spent catalyst removed from the reactor for regeneration will usually have about 0.8-2% by weight carbonaceous deposits.



   The regenerator vessel operates at substantially the same pressure as the reactor vessel and at temperatures of 1050 to 1300 F. Due to the high pressure combustion rate achieved in the hydroforming reaction system, it is advantageous to provide cooling coils in the regenerator to regulate the temperature therein. The average catalyst residence time is on the order of about 3 to 15 minutes, which is more than sufficient to achieve complete catalyst regeneration, i.e., to reduce the amount of carbon on the catalyst. catalyst regenerated at less than 0.3% by weight, and usually at much less than 0.1% by weight.

   Complete regeneration is further indicated by the presence of excess or free oxygen in the flue gases from the regenerator, or by the fact that the average valence rate of the active catalytic component is at its maximum value, that is. that is, 5.7 to 6.0 for catalysts containing molybdenum oxide.



   The catalyst / oil weight ratio introduced into the reactor should be about 0.5 to 1.5. It is preferred to operate at catalyst / oil ratios of about 1, since ratios greater than about 1 to 1.5 result in excessive carbon formation. At higher pressures somewhat higher weight ratios can be used.



   The space velocity or weight in pounds of feed charged per hour per pound of catalyst in the reactor depends on the age or activity level of the catalyst, the type of feed, and the desired octane number of the product. The space velocity for a molybdenum oxide catalyst on alumina can vary, for example, from about 1.5 wt / hour / wt up to about 0.15 wt / hour / wt.



   The following examples illustrate the present invention.



  Example 1
Experiments were carried out in a fluid system laboratory set-up, in batch, to distinguish between standard pretreatment at 900 F with H2 for 15 minutes, and an operation in which no reduction of the catalyst was carried out. was obtained before the feed and recycle gas were introduced into the reactor.

   It is

 <Desc / Clms Page number 10>

 known that reduction at elevated temperatures (1100 - 1200 F) can result in overprocessing or over reduction. Because of the heat of reduction and the heat of adsorption of the water formed in the pretreatment, it is possible to raise the temperature of the catalyst bed significantly during the pretreatment or during the reduction which. is carried out at the same time as the hydroformin cycle, and, in fact, to obtain a reduction at high temperature.

   In these batch "fluid" tests, the heat formed during the reduction was rapidly dissipated in a fluid sand bath surrounding the catalyst bed, so that the temperature rise above the reaction level of 900 F , was only 30 F. This rise in temperature only persisted for 2 to 5 minutes and therefore the reduction effected either before the admission of feed and recycle gas or at the same time as the The intake of feed and recycle gas, was essentially a low temperature reduction.



  The results of the test runs not using a pretreatment and using the standard 15 minute pretreatment with H are given below.



   Operation without pretreatment.
 EMI10.1
 
<tb>



  N <SEP> dressai <SEP> CFS-1-44 <SEP> 1 <SEP> 5
<tb>
<tb>
<tb>
<tb> Cycle <SEP> 1 <SEP> 2 <SEP> 1 <SEP> 2
<tb>
<tb>
<tb>
<tb> Reactor <SEP> temperature <SEP>, <SEP> F <SEP> 900 <SEP> 900 <SEP> 900 <SEP> 900
<tb>
<tb>
<tb>
<tb>
<tb> Weight / hour / weight <SEP> 0.29 <SEP> 0.29 <SEP> 0.30 <SEP> 0.28
<tb>
<tb>
<tb>
<tb>
<tb> <SEP> rate of <SEP> gas <SEP> of <SEP> recycling, <SEP> feet
<tb>
<tb>
<tb> cubes <SEP> per <SEP> barrel <SEP> 3905 <SEP> 3891 <SEP> 4047 <SEP> 4194
<tb>
<tb>
<tb>
<tb> <SEP> octane number <SEP> Res., <SEP> net,
<tb>
<tb>
<tb>
<tb> G5-430 F <SEP> 92.6 <SEP> 91.9 <SEP> 91.3 <SEP> 90.6
<tb>
<tb>
<tb>
<tb> Production, <SEP>% <SEP> vol., <SEP> C-430 F <SEP> 79.1 <SEP> 79.0 <SEP> 79.8 <SEP> 82.3
<tb>
<tb>
<tb>
<tb>
<tb> Gas <SEP> sec, <SEP>% <SEP> weight, <SEP> C3 <SEP> 11.8 <SEP> 12.5 <SEP> 11.2 <SEP> 8,

  9
<tb>
<tb>
<tb>
<tb> Carbon, <SEP>% <SEP> weight <SEP> 0.5 <SEP> 0.6 <SEP> 0.3 <SEP> 0.5
<tb>
<tb>
<tb>
<tb>
<tb> C4, <SEP>% <SEP> volumes <SEP> 7.1 <SEP> 6.5 <SEP> 6.9 <SEP> 7.5
<tb>
   @ feed and recycle gas sent to the reactor simultaneously with a temperature thereof of 900 F.



    @ feed and recycle gas sent to the reactor simultaneously with an initial reactor temperature of 1000 F, quickly lowered to 900 F.



     15 minute pretreatment with H2 at 900 F and an effective pressure of 200 pounds per square inch,
 EMI10.2
 
<tb> N <SEP> test <SEP> CFS-1-43 <SEP> A <SEP> A <SEP> B <SEP> H <SEP> H
<tb>
<tb>
<tb> Cycle <SEP> 1 <SEP> 2 <SEP> 1 <SEP> 1 <SEP> 2
<tb>
<tb>
<tb>
<tb> Reactor <SEP> temperature <SEP>, <SEP> F <SEP> 900 <SEP> 900 <SEP> 900 <SEP> 900 <SEP> 900
<tb>
<tb>
<tb>
<tb>
<tb> Weight / hour / weight <SEP> 0.29 <SEP> 0.29 <SEP> 0.29 <SEP> 0.30 <SEP> 0.28
<tb>
<tb>
<tb>
<tb>
<tb> Rate.

   <SEP> of <SEP> gas <SEP> of <SEP> recycling
<tb>
<tb>
<tb>
<tb> cubic <SEP> feet / barrel <SEP> 2900 <SEP> 3200 <SEP> 2800 <SEP> 3100 <SEP> 3400
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> Index <SEP> doctane <SEP> Reso, <SEP> net,
<tb>
<tb>
<tb>
<tb>
<tb> C5-430 F <SEP> 90.6 <SEP> 91.3 <SEP> 90.4 <SEP> 89.4 <SEP> '88, 9
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> Production, <SEP>% vol, <SEP> C5-430 F <SEP> 82.0 <SEP> 92.4 <SEP> 82.4 <SEP> 82.6 <SEP> 82.2
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> Gas <SEP> sec, <SEP>% <SEP> weight, <SEP> C3 <SEP> 9.6 <SEP> 9.5 <SEP> 9.2 <SEP> 10.2 <SEP> 9 , 9
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> Carbon, <SEP>% <SEP> weight <SEP> 0.4 <SEP> 0.5 <SEP> - <SEP> 0.2 <SEP> 0.3
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> C4, <SEP>% <SEP> volumes <SEP> 5.4 <SEP> 5.1 <SEP> 5.8 <SEP> 6.0 <SEP> 5,

  8
<tb>
 
Note that inactivity of the catalyst without pretreatment could be better than that obtained with standard pretreatment. On a production-octane basis, the selectivity obtained with the different treatments

 <Desc / Clms Page number 11>

 catalysts appear to be equivalent. Carbon yields for non-pretreatment tests may be slightly higher than those for pretreatment tests when considering the difference in recycle gas velocity rates.

   Indeed, during short cycle times - which equates to high catalyst / oil ratios - it is shown that 'un-pretreated catalysts could give much higher carbon productioris, but with long working times. stay in the reactor, as in a continuous operation, where only a very small portion of the catalyst would not be reduced in the reactor at any time, the additional carbon would be negligible.



  Example 2
A number of tests were carried out in a fluid hydroforraing plant handling 50 barrels per day, and operating at a pressure of about 200 pounds per square inch and in contact with a catalyst containing about 9.3% by weight. of molybdenum oxide on alumina. The results obtained are summarized in the table below
 EMI11.1
 
<tb> N <SEP> test <SEP> 1 <SEP> 2 <SEP> 3 <SEP> 4
<tb>
<tb> Reactor <SEP> temperature <SEP>, <SEP> F <SEP> 897 <SEP> 900 <SEP> 901 <SEP> 900
<tb>
<tb>
<tb> Spatial <SEP> speed <SEP> (Weight / hour /
<tb>
<tb> weight) <SEP> 0.25 <SEP> 0.25 <SEP> 0.24 <SEP> 0,

  24
<tb>
<tb>
<tb> Gas <SEP> from <SEP> pretreatment <SEP> none <SEP> none <SEP> hydrogen <SEP> hydrogen
<tb>
<tb>
<tb> Temperature <SEP> of <SEP> pre-treatment <SEP> - <SEP> - <SEP> 1004 <SEP> 996
<tb>
<tb>
<tb> <SEP> duration of <SEP> preprocessing <SEP> - <SEP> - <SEP> 10-15 <SEP> sec. <SEP> 10-15 <SEP> sec.
<tb>
<tb>
<tb>



  Index <SEP> doctance <SEP> CFR <SEP> 96 <SEP> 97 <SEP> 97.8 <SEP> 96.8
<tb>
<tb>
<tb>
<tb> Production <SEP> C5 <SEP> + <SEP> (% <SEP> vol. <SEP>) <SEP> 75.3 <SEP> 73.6 <SEP> 73, at <SEP> 73.3
<tb>
 
These tests clearly show that the regenerated catalyst can be recycled to the reactor without pretreatment or reduction with hydrogen, without loss of activity and selectivity.



   The preceding description contains a limited number of embodiments according to the present invention. It should be understood, however, that various variations are possible without departing from the spirit of the present invention.



    CLAIMS.



   1. In a hydroforming process of hydrocarbons boiling in the boiling range of engine fuels, in contact with hydroforming catalyst particles, finely subdivided, according to the fluidized solids technique, the improvement which comprises: continuously removing a stream of spent catalyst particles from the dense fluidized bed of catalyst particles in the reaction zone; regenerating the removed catalyst particles, by burning off the carbonaceous deposits they carry, with excess air in a regeneration zone; removing a stream of regenerated catalyst from the regeneration zone;

   separating the regeneration gases from the regenerated catalyst and without contacting the freshly regenerated catalyst with gases containing hydrogen; and discharging the freshly regenerated catalyst directly into the dense fluidized bed of catalyst particles in the reaction zone, whereby the freshly regenerated catalyst particles are treated with reactive gases containing hydrogen, while by being in intimate mixture with a significant amount of the catalyst of the reactor.


    

Claims (1)

2. The process as defined in claim 1, wherein the catalytic metal in the regenerated catalyst is oxidized to an average valence value of 5.7 to 6. <Desc / Clms Page number 12> 3. The process as defined in claim 1 wherein the reaction zone is maintained at temperatures of 850-925 ° F and pressures of about 50-500 pounds per square inch, the regeneration zone operates at temperatures of about 1050 to 1200 F and-substantially the same pressure as the reaction zone, and the catalytic metal, in the regenerated catalyst, is oxidized to an average valence value of 5.7 to 6. 4. The process as defined in claim 1, wherein the reaction zone is maintained at temperatures of 8500-925 ° F and pressures of about 50-500 pounds per square inch, the regeneration zone is operated. at temperatures of about 1050 to 1200 F and substantially the same pressure as the reaction zone, and the regenerated catalyst is discharged in this high oxidation state and substantially at regenerator temperature, directly into the reactor. dense catalyst bed of the reaction zone. 5. In a process for hydroforming hydrocarbons in contact with finely subdivided hydroforming catalyst particles using the fluidized solids technique, the improvement which comprises: the continuous removal of a stream of spent catalyst particles out of the dense fluidized bed of catalyst particles in the reaction zone; complete or total regeneration of the removed catalyst particles, by burning the carbonaceous deposits that they carry, in a regeneration zone; removing, from top to bottom, out of the regeneration zone, a stream of regenerated catalyst having a carbon content of less than 0.3% by weight and the catalyst component oxidized to nearly its maximum valence; separating the regeneration gases from the regenerated catalyst stream; the passage of the stream of catalyst particles, regenerated and gas-cleaned, in indirect heat exchange, to the dense fluidized bed of catalyst in the reaction zone and without contact of the freshly regenerated catalyst with gases containing hydrogen or a hydrocarbon feed; discharging the freshly regenerated catalyst directly into the dense fluidized bed of catalyst particles in the reaction zone, whereby the freshly regenerated catalyst particles are treated with hydrogen-containing reactive gases while being intimately mixed with a large amount of the catalyst from the reactor. 6. The process as defined in claim 5, wherein the catalyst / oil ratio is less than about 1. 7. The process as defined in claim 5, wherein the regenerated catalyst stream removed from the regenerator is first scrubbed with air and finally with nitrogen prior to its discharge into the dense bed of the reactor. in appendix 2 drawings.