CA2056196A1 - High activity, high yield tin modified platinum-iridium catalysts, and reforming process utilizing such catalysts - Google Patents
High activity, high yield tin modified platinum-iridium catalysts, and reforming process utilizing such catalystsInfo
- Publication number
- CA2056196A1 CA2056196A1 CA002056196A CA2056196A CA2056196A1 CA 2056196 A1 CA2056196 A1 CA 2056196A1 CA 002056196 A CA002056196 A CA 002056196A CA 2056196 A CA2056196 A CA 2056196A CA 2056196 A1 CA2056196 A1 CA 2056196A1
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- Canada
- Prior art keywords
- percent
- catalyst
- platinum
- iridium
- tin
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- C10G35/00—Reforming naphtha
- C10G35/04—Catalytic reforming
- C10G35/06—Catalytic reforming characterised by the catalyst used
- C10G35/085—Catalytic reforming characterised by the catalyst used containing platinum group metals or compounds thereof
- C10G35/09—Bimetallic catalysts in which at least one of the metals is a platinum group metal
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
- B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
- B01J23/56—Platinum group metals
- B01J23/62—Platinum group metals with gallium, indium, thallium, germanium, tin or lead
- B01J23/622—Platinum group metals with gallium, indium, thallium, germanium, tin or lead with germanium, tin or lead
- B01J23/626—Platinum group metals with gallium, indium, thallium, germanium, tin or lead with germanium, tin or lead with tin
Abstract
ABSTRACT OF THE DISCLOSURE
Tin modified platinum-iridium catalysts provide high yields of C5+ liquid reformate in catalytic reforming, concurrent with high activity. In particular, the tin modified platinum-iridium catalysts are of unusually high selectivity, as contrasted with known iridium promoted platinum catalysts. The high selectivity is manifested in reforming a naphtha feed in a reactor charged to capacity with the catalyst, but particularly when used in the dehydrocyclization zone, or tail reactor of a series of reactors, while the lead reactors of the series contain a non tin-containing platinum catalyst, especially a platinum-iridium, or a platinum-rhenium catalyst. The tin modified platinum-iridium catalysts are also highly active, with only moderate loss in the high activity for which iridium stabilized platinum catalysts are known.
Tin modified platinum-iridium catalysts provide high yields of C5+ liquid reformate in catalytic reforming, concurrent with high activity. In particular, the tin modified platinum-iridium catalysts are of unusually high selectivity, as contrasted with known iridium promoted platinum catalysts. The high selectivity is manifested in reforming a naphtha feed in a reactor charged to capacity with the catalyst, but particularly when used in the dehydrocyclization zone, or tail reactor of a series of reactors, while the lead reactors of the series contain a non tin-containing platinum catalyst, especially a platinum-iridium, or a platinum-rhenium catalyst. The tin modified platinum-iridium catalysts are also highly active, with only moderate loss in the high activity for which iridium stabilized platinum catalysts are known.
Description
2~5~96 , FIELD OF THE_INVENTION
This invention relates to the art of catalytic reforming, and catalysts for use in such process. In particular, it relates to a high activity tin modified platinum-iridium catalyst which is ~ se useful in conducting catalytic reforming, but particularly useful in the tail reactor of a staged reactor system in producing high octane gasoline from naphtha with improved Cs+ liquid yields.
BACKGROUND
In catalytic reforming, a process for improving the octane quality of naphthas or straight run gasolines, a multi-functional catalyst is employed which contains a metal hydrogenation-dehydrogenation (hydrogen transfer) component~ or components, composited with a porous, inorganic oxide support, notably alumina. Noble metal catalysts, notably of the platinum type, are currently employed, reforming being defined as the total effect of the molecular changes, or hydrocarbon reactions, produced by dehydrogenation of cyclohexanes and dehydroisomerization of alkylcyclopentanes to y;eld aromat1cs; dehydrogenation of paraffins to yield olefins;
dehydrocyclization of paraffins and olefins to yield aromatics;
isomerization of n-paraffins; isomerization of alkylcycloparaffins to yield cyclohexanes; isomerization of substituted aromatics; and hydrocracking of paraffins which produces gas, and ;nev;tably coke, the latter being deposited on the catalyst.
In a reforming operation, one or a series of reactors, or a series of reaction zones, are employed. Typically, a series of reactors is employed, e.g., three or four reactors, these constituting the heart of the reforming unit. Each reforming reactor is generally provided with a fixed bed, or beds, of the catalyst which receive downflow feed, and each is provided with a preheater or interstage heater, because the reactions which take place are endothermic. A naphtha feed, with 31 hydrogen, or recycle hydrogen gas, is passed through a preheat furnace and reactor and then in sequence through subsequent interstage heaters , .:
' `` ` 20~1 9~
and reactors of the series. The product from the last reactor is separated into a liquid fraction, and a vaporous effluPnt. The former is recovered as a Cs+ liquid product. The latter is a gas rich in hydrogen, and usually contains small amounts of normally gaseous hydrocarbons, from which hydrogen is separated and recycled to the process to minimize coke production.
The sum-total of the reforming reactions, supra, occurs as a continuum between the first and last reactor of the series, i.e., as the feed enters and passes over the first fixed catalyst bed of the first reactor and exits from the last fixed catalyst bed of the last reactor of the series. The reactions which predominate between the several reactors differ dependent principally upon the nature of the feed, and the temperature employed within the individual reactors. In the initial reaction zone, or first reactor, which is maintained at a relatively low temperature, it is believed that the primary reaction involves the dehydrogenation of naphthenes to produce aromatics. The isomerization of naphthenes, notably C5 and C6 naphthenes, also occurs to a considerable extent. Most of the other reforming reactions also occur, but only to a lesser, or smaller extent. There is relatively little hydrocracking, and very little olefin or paraffin dehydrocyclization occurring in the first reactor. Within the intermediate reactor zone(s), or reactor(s), the temperature is maintained somewhat higher than in the first, or lead reactor of the series, and it is believed that the primary reactions in the intermediate reactor, or reactors, involve the isomerization of naphthenes and paraffins. Where, e.g., there are two reactors disposed between the first and last reactor of the series, it is believed that the principal reaction involves the isomerization of naphthenes, normal paraffins and isoparaffins. Some dehydrogenation of naphthenes may, and usually does occur, at least within the first of the intermediate reactors. There is usually some hydrocracking, at least more than in the lead reactor of the series, and there is more olefin and paraffin dehydrocyclization. The third reactor of the series, or second intermediate reactor, is generally operated at a somewhat higher temperature than the second reactor of the series. It is believed that the naphthene and paraffin isomerization reactions 20~19~
This invention relates to the art of catalytic reforming, and catalysts for use in such process. In particular, it relates to a high activity tin modified platinum-iridium catalyst which is ~ se useful in conducting catalytic reforming, but particularly useful in the tail reactor of a staged reactor system in producing high octane gasoline from naphtha with improved Cs+ liquid yields.
BACKGROUND
In catalytic reforming, a process for improving the octane quality of naphthas or straight run gasolines, a multi-functional catalyst is employed which contains a metal hydrogenation-dehydrogenation (hydrogen transfer) component~ or components, composited with a porous, inorganic oxide support, notably alumina. Noble metal catalysts, notably of the platinum type, are currently employed, reforming being defined as the total effect of the molecular changes, or hydrocarbon reactions, produced by dehydrogenation of cyclohexanes and dehydroisomerization of alkylcyclopentanes to y;eld aromat1cs; dehydrogenation of paraffins to yield olefins;
dehydrocyclization of paraffins and olefins to yield aromatics;
isomerization of n-paraffins; isomerization of alkylcycloparaffins to yield cyclohexanes; isomerization of substituted aromatics; and hydrocracking of paraffins which produces gas, and ;nev;tably coke, the latter being deposited on the catalyst.
In a reforming operation, one or a series of reactors, or a series of reaction zones, are employed. Typically, a series of reactors is employed, e.g., three or four reactors, these constituting the heart of the reforming unit. Each reforming reactor is generally provided with a fixed bed, or beds, of the catalyst which receive downflow feed, and each is provided with a preheater or interstage heater, because the reactions which take place are endothermic. A naphtha feed, with 31 hydrogen, or recycle hydrogen gas, is passed through a preheat furnace and reactor and then in sequence through subsequent interstage heaters , .:
' `` ` 20~1 9~
and reactors of the series. The product from the last reactor is separated into a liquid fraction, and a vaporous effluPnt. The former is recovered as a Cs+ liquid product. The latter is a gas rich in hydrogen, and usually contains small amounts of normally gaseous hydrocarbons, from which hydrogen is separated and recycled to the process to minimize coke production.
The sum-total of the reforming reactions, supra, occurs as a continuum between the first and last reactor of the series, i.e., as the feed enters and passes over the first fixed catalyst bed of the first reactor and exits from the last fixed catalyst bed of the last reactor of the series. The reactions which predominate between the several reactors differ dependent principally upon the nature of the feed, and the temperature employed within the individual reactors. In the initial reaction zone, or first reactor, which is maintained at a relatively low temperature, it is believed that the primary reaction involves the dehydrogenation of naphthenes to produce aromatics. The isomerization of naphthenes, notably C5 and C6 naphthenes, also occurs to a considerable extent. Most of the other reforming reactions also occur, but only to a lesser, or smaller extent. There is relatively little hydrocracking, and very little olefin or paraffin dehydrocyclization occurring in the first reactor. Within the intermediate reactor zone(s), or reactor(s), the temperature is maintained somewhat higher than in the first, or lead reactor of the series, and it is believed that the primary reactions in the intermediate reactor, or reactors, involve the isomerization of naphthenes and paraffins. Where, e.g., there are two reactors disposed between the first and last reactor of the series, it is believed that the principal reaction involves the isomerization of naphthenes, normal paraffins and isoparaffins. Some dehydrogenation of naphthenes may, and usually does occur, at least within the first of the intermediate reactors. There is usually some hydrocracking, at least more than in the lead reactor of the series, and there is more olefin and paraffin dehydrocyclization. The third reactor of the series, or second intermediate reactor, is generally operated at a somewhat higher temperature than the second reactor of the series. It is believed that the naphthene and paraffin isomerization reactions 20~19~
continue as the primary reaction ;n this reactor, but there is very little naphthene dehydrogenation. There is a further increase in paraffin dehydrocyclization, and more hydrocracking. In the final reaction ~one, or final reactor, which is operated at the highest temperature of the series, it is believed that paraffin dehydrocyclization~ particularly the dehydrocyclization of the short chain, notably C6 and C7 paraffins, is the primary reaction. The isomerization reactions continue, and there is more hydrocracking in this reactor than in any one of the other reactors of the series.
The activity of the catalyst gradually declines due to the build-up of coke. Coke formation is believed to result from the deposition of coke precursors such as anthracene, coronene, ovalene, and other condensed ring aromatic molecules on the catalyst, these polymeri~ing to form coke. During operation, the temperature of the the process is gradually raised to compensate for the activity loss caused by the coke deposition. Eventually, however, economics dictate the necessity of reactivating the catalyst. Consequently, in all processes of this type the catalyst must necessarily be periodically regenerated by burning of the coke at controlled conditions.
THE INVE~TION
In accordance with the present invention, there is provided:
(i) a novel catalyst composition comprised of from about 0.1 percent to about 1.0 percent platinum, preferably from about 0.2 to about 0.7 percent platinum, from about 0.1 percent to about 1.0 percent iridium, preferably from about 0.2 to about 0.7 percent iridium, and from about 0.02 percent to about 0.4 percent tin, preferably from about 0.05 to about 0.3 percent tin, based on the total weight of the catalyst (dry basis), uniformly dispersed throughout a particulate solid support. Suitably, the weight ratio of the (platinum ~ iridium):tin will range from about 2:1 to about 25:1, preferably from about 5:1 to about 15:1, based on the total weight of platinum, iridium and tin in the catalyst composition. Suitably, the catalyst also contains halogen, 20~196 preferably chlor;ne, in concentration ranging from about 0.1 percent to about 3 percent, preferably from about 0.8 to about 1.5 percent, based on the total weight of the catalyst. Preferably also, the catalyst ;s sulfided, e.g., by contact w1th a hydrogen sulfide-containing gas, and contains from about 0.01 percent to about 0.2 percent9 more preferably from about 0.05 percent to about 0.15 percent sulfur, based on the total weight of the catalyst. The metal components, in the amounts stated, are uniformly dispersed throughout an inorganic oxide support, preferably an alumina support and more preferably a gamma alumina support, and (ii) a novel process for improving the octane quality of a naphtha in a reforming unit comprised of a plurality of serially connected reactors inclusive of one or more lead reactors and tail reactor, the lead reactors of which are provided with a platinum catalyst, preferably a rhenium-promoted or iridium-promoted platinum catalyst, and the tail reactor with a catalyst as described in (i), supra. A process of this type, it has been found, results in the suppression of excessive dealkylation reactions with simultaneous ;ncrease in dehydrocyclization reactions to increase C5+ liquid yields, with only a modest act;vity deb;t vis-a-vis the use of a catalyst in the tail reactor which ;s otherwise similar but does not contain the t;n, or contains tin in greater or lesser amounts than that prescribed for the tail reactor catalyst of this invention. In addition to the increased C5+ liquid yields, temperature runaway rate during process upsets is tempered, and reduced; the amount of benzene produced in the reformate at similar octane levels is reduced, generally as much as about 10 percent to about 15 percent, based on the volume of the C5+
liquids, and there is lower production of fuel gas, a product of relatively low value.
The process of this invention requires the use of the platinum-iridium catalyst, modified or promoted with the relatively small and infin;tesimal amount of t;n, w;thin the reforming zone wherein the primary, or predominant reaction involves the dehydrocyclization of paraff;ns, and olefins. This zone, termed the "paraffin 2~6196 dehydrocyclization zone1" is invariably found in the last reactor or zone of the series. Generally, the tail reactor of a series of reactors contains from about 55 percent to about 70 percent of the total ca~alyst charge, based on the total weight of catalyst in the reforming unit.
Of course, where ~here is only a single reactor, quite obviously the paraffin dehydrocyclization reaction will predominate in the catalyst bed, or beds defining the zone located at the product exit side of the reactor. Where there are multiple reactors, quite obviously as has been suggested, the paraffin dehydrocyclization reaction w;ll predominate in the catalyst bed, or beds defining a zone located at the product exit side of the last reactor of the series. Often the paraffin dehydro-cyclization reaction is predominant of the sum-total of the reactions which occur within the catalyst bed, or beds constituting the last reactor of the series dependent upon the temperature and amount of catalyst that is employed in the final reactor vis-a-vis the total catalyst contained in the several reactors, and temperatures maintained in the other reactors of the reforming unit.
In one of its preferred aspects, promoted platinum, or platinum-rhenium catalyst is employed in the reforming zones in front of, or in adYance uf the paraffin dehydrocyclization zone, viz., the naphthene dehydrogenation zone, or zones, alnd the isomerization zone, or zones. Or, preferably also, an iridium promoted platinum, or platinum-ir;dium catalyst can be employed in the reforming zones in front of, or in advance of the paraffin dehydrocyclization zone, viz. the naphthene dehydrogenation zone, or zones, and the isomerization zone, or zones. Suitably, where a platinum-rhenium or platinum-iridium catalyst is employed, the weight ratio of the rhenium:platinum, or weight ratio of the iridium: platinum, respectively, will range from about 0.1:1 to about 1:1, preferably from about 0.5:1 to about 1:1, with the absolute concentration of the platinum ranging from about O.1 percent to about 1.0 percent, preferably from about 0.2 percent to about 0.7 percent, based on the total weight of the catalyst composition.
The catalyst employed in accordance with this invention is necessarily constituted of composite particles which contain, besides a 20~9~
support material, the hydrogenation-dehydrogenation components, a halide component and, preferably, the catalyst is sulf;ded. The support material is constituted of a porous, refractory inorganic oxide, particularly alumina. The support can contain, e.g., one or more alumina, bentonite, clay, diatomaceous earth, 7eolite, silica, activated carbon, magnesia, zirconia, thoria, and the like; though the most preferred support is alumina to wh;ch, if desired, can be added a suitable amount of other refractory carrier materials such as silica, zirconia, magnesia, t;tan;a, etc., usually in a range of about 1 to 20 percent, based on the weight of the support. A preferred support for the practice of the present invention is one having a surface area of more than 50 m2/g9 preferably from about 100 to about 300 m2/g, a bulk density nf about 0.3 to 1.0 g/ml, preferably about 0.4 to 0.8 g/ml, an average pore volume of about 0.2 to 1.1 ml/g, preferably about 0.3 to 0.8 ml/g, and an average pore diameter of about 30 to 300 Angstrom units.
The metal hydrogenation-dehydrogenation components can be uniformly dispersed throughout the porous inorganic oxide support by various techniques known to the art such as ion-exchange, coprecipi-tation with the alumina in the sol or glel form, and the like. For example, the catalyst composite can be formed by adding together suitable reagents such as a salt of tin, and ammonium hydroxide or carbonate, and a salt of aluminum such as aluminum chloride or aluminum sulfate to form aluminum hydroxide. The aluminum hydroxide containinq the tin salt can then be heated, dried, formed into pellets or extruded, and then calcined ;n air or n;trogen up to 540C. The other metal components can then be added. Suitably, the metal components can be added to the catalyst by impregnation, typically via an "incipient wetness" technique which requires a minimum of solution so that the total solution is absorbed, initially or after some evaporation.
It is preferred, in forming the catalysts of this invention, to deposit the t;n first, and the add;tional metals are then added to a previously pilled, pelleted, beaded, extruded, or sieved tin conta;n;ng particulate support mater;al by the ;mpregnation method. Pursuant to 20~19~
the impregnation method, porous refractory inorganic oxides in dry or solvated state are contacted, either alone or admixed, or otherwise incorporated with a metal or metals-containing solution, or solutions, and thereby impregnated by either the "incipient wetness" technique, or a technique embodying absorption from a dilute or concentrated solution, or solutions, with subsequent filtration or evaporation to effect total uptake of the metallic components which are uniformly dispersed throughout the particulate solids support.
In the step of forming the tin-containing support, a tin salt, e.g., stannous chloride, stannic chloride, stannic tartrate, stannic nitrate, or the like, can be uniformly dispersed throughout a solid support or carrier by the method described in U.S. Patent 4,963,249 which was issued on October 16, 1990 to William C. Baird, Jr. et al, specific reference being made to Column 6, lines 15 through 23, and Columns 58 through 69, inclusively, herewith incorporated and made of reference. In forming the lead reactor catalysts, the step of incorporating tin into the support is omitted, while other metallic components are added to the support by impregnation.
Platinum in absolute amount is usually supported on the carr~er within the range of from about 0.1 to about 1.0 percent, preferably from about 0.2 to about 0.7 percent, based on the weight of the catalyst (dry basis). Iridium, in absolute amount, is also usually supported on the carrier within the range of from about 0.1 to about 1.0 percent, preferably from about 0.2 to about 0.7 percent, based on the weight of the catalyst (dry basis). Rhenium, in absolute amount, where a platinum-rhenium catalyst is formed for use in the lead reactors, is also usually supported on the carrier in concentration ranging from about 0.1 to about 1.0 percent, preferably from about 0.2 to about 0.7 percent, based on the weight of the catalyst (dry basis). The tin, where added to the support to form the catalyst of this invent;on, preferably before addition of the platinum and iridium, is added to the support in concen~ration ranging from about 0.02 percent to about 0.4 percent, preferably from about 0.05 to about 0.3 percent, based on the total weight of the catalyst (dry basis). The weigh$ ratio of the 2~6 3 g~
(platinum ~ iridium):tin suitably ranges from about 2:1 ~o about 25:1, preferably from about 5:1 to about 15:1, based on he total weight of the platinum, iridium, and tin in the catalyst composition.
To enhance catalyst performance in reforming operations, it is also required to add a halogen component to the catalysts, fluorine and chlorine being preferred halogen components. The halogen is con-tained on the catalyst within the range of 0.1 to 3 percent, preferably within the range of about 0.8 to about 1.5 percent, based on the weight of the catalyst. When using chlorine as the halogen component, it is added to the catalyst within the range of about 0.2 to 2 percent, preferably within the range of about 0.8 to 1.5 percent, based on the weight of the catalyst. The introduction of halogen into the catalyst can be carried out by any method at any time. It can be added to the catalyst during catalyst preparation, for example, prior to, following or simultaneously with the incorporation oF a metal hydrogenation-dehydrogenation component, or components. It can also be introduced by contacting a carrier material in a vapor phase or liquid phase with a halogen compound such as hydrogen fluoride, hydrogen chloride, ammonium chloride, or the like.
The catalyst is dried by heating at a temperature above about 25C., preferably between about 65C. and 150C., in the presence o$ nitrogen or oxygen, or both, in an air stream or under vacuum. The catalyst is calcined at a temperature between about 200C. to 455C., either in the presenc~ of oxygen in an air stream or in the presence of an inert gas such as nitrogen.
Sulfur is a highly preferred component of the catalysts, the sulfur content of the catalyst generally ranging to about 0.2 percent, preferably from about 0.05 percent to about 0~15 percent, based on the weight of the catalyst (dry basis). The sulfur can be added to the catalyst by conventional methods, suitably by breakthrough sulfiding of a bed of the catalyst with a sulfur-containing gaseous stream, e.g., hydrogen sulfide in hydrogen, performed at temperatures ranging from about 175C. to about 565C.9 and at pressures ranging from about 1 to 2 ~ 9 ~
about 40 atmospheres for the time necessary to achieve breakthrough, or the desired sulfur level.
The feed or charge stock can be a virgin naphtha, cracked naphtha, a naphtha from a coal liquefaction process, a Fischer-Tropsch naphtha, or the like. Typical feeds are those hydrocarbons containing from about 5 to about 12 carbon atoms, or more preferably from about 6 to about 9 carbon atoms. Naphthas, or petroleum fractions boiling within the ranye of from about 25DC. to about 235~C., and preferably from about S0C. to about 190C., contain hydrocarbons of carbon numbers within these ranges. Typical fract;ons thus usually contain from about 15 to about 80 vol. % paraffins, both normal and branched, which fall in the range of about C5 to Cl2, from about 1~ to 80 vol. % of naphthenes falling within the range of from about C6 to C12, and from 5 through 20 vol. % of the desirable aromatics falling within the range of from about C6 to Cl2.
The reforming runs are initiated by adjusting the hydrogen and feed rates, and the temperature tEquivalent Isothermal Temperature) and pressure to operating conditions. The run is continued at optimum reforming conditions by adjustment of the major process variables, within the ranges described below:
Lead Reactor Condltions Major OperatingTypical Process Preferred Process VariablesConditions Condit;ons Pressure, psig 100-700 150-500 Reactor Temp., C. 370-540 425-510 Recycle Gas Rate, SCF/B 2000-10,000 2000-6000 Fced Rate, ~/Hr/W 1-20 2-10 ; Tail Reactor Conditions Major OperatingTypical Process Preferred Process Variabl esCond i t i on s Conditions Pressure, psig 100-700 150-500 Reactor Temp., C. 425-540 455-525 Recycle Gas Rate, SCF/B 2000-10,000 2000-6000 Feed Rate, W/Hr/W 1-10 2-8 2~56~6 The invention will be more fully understood by reference to the follow;ng comparative data illustrating its more salient features.
All parts are given in terms of weight except as otherwise specified.
The fsll DWi ng examples, and comparative demonstrations, are exemplary of the high activity, and selectivity of the catalysts of this invention; particularly, when employed in the paraffin dehydro-cyclization zone of the series of reaction zones while a different platinum catalyst is employed in the lead reaction zones. In the examples and demonstrations which follow all parts are in terms of weight units, pressures in terms of pounds per square inch gauge, and temperatures are given in Fahrenheit degrees except as otherwise expressed.
In conducting these tests, an n-heptane feed was used in certain instances. In others a full range naphtha was employed.
Inspect;ons on the fu11 range Arab Light Naphtha feed employed in making certain of the tests ar~ given below.
PropertY Arab Liqht Naphtha Gravity at 15C
Specific 0.7412 Octane, RON Clear 38 Molecular Weight 111.3 Sulfur, wppm 0-3 Distillation D-86, C
IBP 90.0 5% 102.5 10% 105.0 50O~o 125.0 90% 154.0 160.0 FBP 171.0 Composition, Wt. %
Total Paraffins 65.1 Total Naphthenes 19.3 Total Aromatics 15.6 2~$~
"
In a first series of runs, the performance of the platinum-iridium-tin catalysts of this invention was compared with a platinum-iridium (0.6% Pt/0.6% Ir) catalyst, a highly active catalyst, in reforming a heptane feed at 100 psig and 350 psig, respectively. The platinum-iridium catalysts were prepared by coimpregnation of l/lÇ inch diameter gamma alumina extrudates with an aqueous solution of chloro-plat;n;c acid and chloroiridic acid to uniformly disperse the metals throughout the extrudates, and this step was followed by drying, and calcination at 260C. The piatinum and iridium metal components of the platinum-iridium-tin catalysts were prepared in similar manner after forming alumina extrudates throughout which tin had been uniformly dispersed in amounts of 0.05% Sn, 0.1% Sn and 0.3% Sn, respectively, during preparation of the alumina support material.
The catalysts, after their preparation in this manner, were charged to capacity in a single reactor and heated to 400C. in air for three hours. Following three hours in air at 400C., the catalyst was heated to 455C., reduced with H2, and all of the catalysts, except one as indicated, were then sulfided with H2S in hydrogen at 455C. The heptane feed was then introduced ta a reactor in conducting a series of runs, respectively, a base run with the platinum-iridium catalyst, and runs with each of the catalysts modified with different concentrations, respectively, of the tin. The conditions of operation, and results achieved with each of the catalysts are given in Table lA (100 psig) and Table 1B (350 psig), respectively, as follows:
2 ~ 6 Table lA
HePtane Reformln~_at 100 DSiq 500C, 20 W/H/W, H2/Oil = 6 0.6% Pt/0.6% Ir with~ n 0.05/O Sn 0.1% Sn 0.3% Sn Sul f i ded Yes Yes Yes Yes Yield, Wt.%
Cl ~.4 2.3 2.1 1.6 i-~4 2.9 2.9 2.6 3.2 n-C4 6.4 6.0 6.3 5.3 Cs+ 75.9 77.3 77.9 79.4 Toluene 30.8 31.0 31.9 31.3 Conversion 70.0 71.4 72.6 66.1 Toluene Rate 6.3 6.4 6.5 6.4 Toluene Selectivity 44.3 43.4 44.1 47.4 Table lB
Heptane_Reforminq at 350 PS;q 480C, 80 W/H/W, H2/Oil - 3 0.6% Pt/0.6% Ir withni~ Sn 0.1% Sn 0.3% Sn 0.3% Sn (BASE) Sulfided Yes Yes Yes No Yield, Wt.~
Cl 2.5 2.1 1.1 3.2 i-C4 0.5 0.4 0.8 0.4 n-C, 9.9 9.2 6.2 5.8 C5~ ' 70.0 73O~ 82.6 79.3 Toluene 10.5 10 0 6.3 6.3 Conversion 52.0 46 4 33.8 38.3 Toluene Rate 8.4 8 0 5.1 6.5 Toluene Selectivity 20.4 21.7 18.7 17.2 These data, obtained by light product analyses over a four hour period, show that tin suppresses methane and ethane yields, and the C5~ liquid yield is considerably improved. Activity, as determined by conversion and toluene rate, compares well with the base case at 100 ps;g. At 350 psig however, 0.3% tin d;minishes the activity. The use of an unsulfided catalyst, used in an attempt to compensate for the diminished activity, produces excessive methane formation. A catalyst having 0.1% tin was found to increase the C5+ liquid yield with only a modest activity debit.
, i ,.... .
20~6196 In a second series of runs, a full range naphtha was reformed in recycle pilot plant runs over a catalyst charged to capacity in a single reactor, i.e., a tin modified platinum-iridium catalyst (0.6% Pt/0.6% Ir/0.1% Sn), and its performance compared in similar runs with known platinum-iridium catalysts which did not contain any tin, viz., Catalyst A ~0.6% Pt/0.6% Ir) and Catalyst B ~0.3% Pt/0.3% Ir). In conducting these runs, ten to twenty material balances were made over a period of several weeks and the results recorded and averaged. The results, and the conditions of operation, are given in Table 2.
Table 2 Naphtha Reforminn with Pt-Ir CatalYsts 470C-505C, 375 PSIG, 3500 SCF/B Recycle Gas, 4 W/H/W, H2/Oil = 2.5, RON = 100 A This invention B
(0.6% Pt/(0.6% Pt/0.6% Ir/ (0.3% ~t/
Catalyst 0.6% Ir) _ 0.1% Sn) 0.3% Ir) Relative Activity Number 310 260 220 Cs+ @ 100 RON, LV% 68.6 70.8 68.2 Wt.% @ 100 RON
H2 1.2 1.3 1.3 C1 6.2 5.4 5.9 C2 6.~ 5.4 6.0 C3 5.4 5.1 5.6 C4 6.~ 6.2 6~8 C5+ 74.8 76.5 74.2 These data clearly show that the tin modified platinum-;r;d;um catalyst of th;s ;nvention produces a 2.2 Vol.% Cs+
l;qu;d y;eld ;mprovement over a reform;ng operat;on conducted with Catalyst A, and a 2.6 Vol.% C5~ liquid yield ;mprovement over one conducted with Catalyst B~ The activity of the catalyst of this invention is only slightly less than that of Catalyst A.
...
.
2 ~ 9 ~
The following example, Example 3, simulates a staged reactor system wherein platinum-iridium catalysts are employed in the lead reactors of the series, and a tin-modified platinum-iridium catalyst is employed in the tail reactor of the series.
In a pair of additional runs, a full range naphtha was reformed in a simulated series of reactors at similar conditions except that in this instance, the front 45% of the reactor volume in each of the pair of runs was charged with a platinum-iridium (0.3% Pt/0.3% Ir) catalyst, i.e., Catalyst B as identified in Example 2, and the catalyst charged to the exit side of the reactor (rearward 55% of the reaotor volume) was ~1) a non-tin modified platinum-iridium (0.6% Pt/0.6% Ir) catalyst, Catalyst A as identified in Example 2, and (2) a tin modified platinum-iridium (0.6% Pt/0.6% Ir/Q.1% Sn) catalyst, a catalyst of this invention, as identified in Example 2. The results, and the conditions of operation, are given in Table 3.
Table 3 Naphtha Reforminq with Staqec! Pt-Ir CatalYsts 470C-505aC, 375 PSIG, 3500 SCF/B Recycle Gas, 4 W/H/W, H2/Oil = 2.5, RON = 100 Catalyst Loading Forward 45% B (0~3% Pt/0.3% Ir) B (0.3% Pt/0.3% Ir) Rearward 55% A (0.6% Pt/0.6% Ir) Catalyst of this Invention (0.6%
Pt/0.6% Ir/0.1% Sn) Relative Activity Number 290 250 C5~ @ 100 RON, LY% 68.0 70.0 Wt.% @ 100 RON
H2 1.2 1.4 Cl 6.3 5.1 C2 6.5 5.5 C3 6.0 5.8 c4 6.3 6.3 C5+ 74.5 76.1 - 2~6~
These data clearly demonstrate that the catalyst of this invention, employed in the dPhydrocyclization 70ne of the reactor, provides lower gas make and a 2.0 Vol.% C5+ liquid yield boost with only a modest activity loss.
The following example and comparative demonstratisns, like those described by reference to Example 1, demonstrate the selectivity advantages that can be obtained by the use of tin to modify the characteristirs of a platinum-iridium catalyst; differing from Example 1 in that the catalyst contains lesser amounts of the platinum and iridium metal components.
Example 1, and comparative demonstrations, were repeated, heptane being passed over, at 100 psig and 350 psig, respectively, a platinum-iridium (0.3% Pt/0.3% Ir) catalyst -- the base catalyst --, platinum-iridium catalysts modified with varying amounts of tin, viz., 0.05% Sn, 0.1% Sn and 0.3% Sn, respectively, and a platinum- rhenium catalyst charged to capacity in a single reactor. The conditions of operation, and the results obtained are given in Tables 4A and 4B, respectively.
Table 4A
HeDtane Reforminq at 100 psiq 500-C, 20 W/H/W, Hz/Oil = 6 0.3% Pt/0.3% Ir withnil Sn0.05% Sn0.1% Sn 0.3% Sn0.3%Pt/
(BASE) 0.7%Re Sulfided Yes Yes Yes Yes Yes Yield, Wt. %
Cl 1.8 1.8 1.5 1.4 0.9 i C4 2.8 3.0 ~.4 2.9 3.0 n-C4 5.0 4.9 4.4 4.1 4.1 C5~ 80.4 ~0.6 83.2 82.7 83.4 Toluene 29.0 27.2 25.9 27.8 20.5 Conversion 62.3 62.7 57.7 58 50.7 Toluene Rate 5.9 5.6 5.3 5.7 4.2 Toluene SelectiYity46.3 43.3 44.9 47.9 40.4 Table 4B
Heptane Reforminq at 350 p_~
480C, 80 W/H/W, H2/Oil = 3 0.3%Pt/0.3%Ir nil Sn 0.05%Sn0.1%Sn 0.3%Sn 0.3%Sn Pt/Re with (BASE) 0.3%/0.7%
Sulfided Yes Yes Yes Yes No Yes Yield, Wt.%
Cl 1.3 1.1 n.s 0.6 305 0.3 i-C4 1.0 1.1 0.7 0.8 U.5 0.$
n-C4 7.9 6.9 5.5 4.3 6.3 2.0 C5+ 79.1 81.8 85.7 88.6 77.7 94.6 Toluene 10.1 8.7 7.1 6.7 5.7 4.2 Conversion 46.3 41.5 31.8 26.4 42.5 13.3 Toluene Rate 8.1 7.0 5.7 5.4 4.3 3.3 Toluene Selectivity 21.8 21.0 22.4 25.5 13.5 31.1 These data clearly show that the iridium modifier added to platinum provides a higher conversion and toluene rate than rhenium.
Normally however this increased activity is accompanied by lower Cs+
liquid yields caused by excessive metals dealkylation. The use of tin as a modifier suppresses iridium metal dealkylation, permitting higher C5+ liquid yields than a non-tin modified platinum-iridium catalyst. On the other hand, whereas some activity is lost by the platinum-iridium catalyst as a result ~f the added tin, the activity loss is very modest. Tin suppresses methane and ethane yields when added in small, and infinitesimal amount to platinum-iridium catalysts, as shown by these data, but yet the activity of the tin modified platinum-iridium catalysts is still super;or to conventional plat;num-rhenium catalysts.
Tin added to the platinum-iridium catalyst has a pronounced Cs+ liquid yield benefit at higher pressure.
Staged platinum-rhenium catalysts are currently widely employed as high pressure reforming catalysts in commercial reforming units. The reactors in these units are filled to capacity with the catalyst, and the octane barrel production is constrained by the ac$ivity of the platinum-rhenium catalysts. Increasing octane demand provides strong incent;ves for catalysts with higher activity than the :
.. ~ .
~5~
commerc;al platinum-rhenium catalysts at equivalent C5+ l;quid yield.
The catalyst of this invention, as demonstrated by the following example, can provide higher act;vity with C5+ liquid yield equivalent to the platinum-rhenium catalysts. Replacing, e.g., a presently used 0.3%
Pt/0.7% Re catalyst with a tin modif;ed platinum-ir;dium (0.3% Pt/0.3%
Ir) catalyst ean give a significant act;vity boost without yield debit, as shown by the following data.
A full range naphtha feed was reformed in parallel runs, at similar cond;tions, in a reactor the forward 45% of the available reactor space of which contained a platinum-rhenium (0.3% Pt/0.3% Re) catalyst, Catalyst C, and the rearward 55% of the available reactor space of wh;ch, in a f;rst run was packed with (1) a platinum-rhenium (0.3% Pt/0.7% Re) catalyst, Catalyst D, and, in a second run, (2) with a tin modified platinum-;r;d;um (0.3/0 Pt/0.3% Ir/0.1% Sn) catalyst, a catalyst of th;s ;nvent;cn.
Table 5 Naphtha Reforminq with Staqed Pt-Re~Pt-Ir Catalvsts 470C-525C, 375 PSIG, 2 W/H/W, 3.5 kSCF/B Recycle, H2/Oil 5 2.5, RON - 100 Catalyst Forward 45%C(0.3%Pt/0.3%Re) C(0.3%Pt/0.3%Re) Rearward 55%D(0.3%Pt/0.7%Re~ 0~3%PtJO.3%Ir/0.1%Sn Relative Activity 60 120 C + ~ 100 RON, LV% 69 70 .% @ 100 RON
H21.4 1.4 Cl2.7 3.7 C25.5 5.3 C37.5 6.3 C48.3 7.6 C5+ 74.5 7~.6 These data thus show a profound increase in activity using the tin modifi~d platinum-iridium catalyst of this invention in the 2 ~ 6 hydrodecyclization zone, or exit s;de of the reactor. Thus, the activity of the tin modified platinum-ir;d;um catalyst used only in the rearward side of the reactor space doubled the activity of the total catalyst used in the system, and reduced gas make as well as having increased the C5+ liquid yield by 1.0 Vol.%. In addition, this catalyst has been found to temper temperature runaway rates during process upsets as contrasted with conventional platinum-iridium catalysts.
It is apparent that various modifications and changes can be made without departing the spirit and scope of the invention.
The activity of the catalyst gradually declines due to the build-up of coke. Coke formation is believed to result from the deposition of coke precursors such as anthracene, coronene, ovalene, and other condensed ring aromatic molecules on the catalyst, these polymeri~ing to form coke. During operation, the temperature of the the process is gradually raised to compensate for the activity loss caused by the coke deposition. Eventually, however, economics dictate the necessity of reactivating the catalyst. Consequently, in all processes of this type the catalyst must necessarily be periodically regenerated by burning of the coke at controlled conditions.
THE INVE~TION
In accordance with the present invention, there is provided:
(i) a novel catalyst composition comprised of from about 0.1 percent to about 1.0 percent platinum, preferably from about 0.2 to about 0.7 percent platinum, from about 0.1 percent to about 1.0 percent iridium, preferably from about 0.2 to about 0.7 percent iridium, and from about 0.02 percent to about 0.4 percent tin, preferably from about 0.05 to about 0.3 percent tin, based on the total weight of the catalyst (dry basis), uniformly dispersed throughout a particulate solid support. Suitably, the weight ratio of the (platinum ~ iridium):tin will range from about 2:1 to about 25:1, preferably from about 5:1 to about 15:1, based on the total weight of platinum, iridium and tin in the catalyst composition. Suitably, the catalyst also contains halogen, 20~196 preferably chlor;ne, in concentration ranging from about 0.1 percent to about 3 percent, preferably from about 0.8 to about 1.5 percent, based on the total weight of the catalyst. Preferably also, the catalyst ;s sulfided, e.g., by contact w1th a hydrogen sulfide-containing gas, and contains from about 0.01 percent to about 0.2 percent9 more preferably from about 0.05 percent to about 0.15 percent sulfur, based on the total weight of the catalyst. The metal components, in the amounts stated, are uniformly dispersed throughout an inorganic oxide support, preferably an alumina support and more preferably a gamma alumina support, and (ii) a novel process for improving the octane quality of a naphtha in a reforming unit comprised of a plurality of serially connected reactors inclusive of one or more lead reactors and tail reactor, the lead reactors of which are provided with a platinum catalyst, preferably a rhenium-promoted or iridium-promoted platinum catalyst, and the tail reactor with a catalyst as described in (i), supra. A process of this type, it has been found, results in the suppression of excessive dealkylation reactions with simultaneous ;ncrease in dehydrocyclization reactions to increase C5+ liquid yields, with only a modest act;vity deb;t vis-a-vis the use of a catalyst in the tail reactor which ;s otherwise similar but does not contain the t;n, or contains tin in greater or lesser amounts than that prescribed for the tail reactor catalyst of this invention. In addition to the increased C5+ liquid yields, temperature runaway rate during process upsets is tempered, and reduced; the amount of benzene produced in the reformate at similar octane levels is reduced, generally as much as about 10 percent to about 15 percent, based on the volume of the C5+
liquids, and there is lower production of fuel gas, a product of relatively low value.
The process of this invention requires the use of the platinum-iridium catalyst, modified or promoted with the relatively small and infin;tesimal amount of t;n, w;thin the reforming zone wherein the primary, or predominant reaction involves the dehydrocyclization of paraff;ns, and olefins. This zone, termed the "paraffin 2~6196 dehydrocyclization zone1" is invariably found in the last reactor or zone of the series. Generally, the tail reactor of a series of reactors contains from about 55 percent to about 70 percent of the total ca~alyst charge, based on the total weight of catalyst in the reforming unit.
Of course, where ~here is only a single reactor, quite obviously the paraffin dehydrocyclization reaction will predominate in the catalyst bed, or beds defining the zone located at the product exit side of the reactor. Where there are multiple reactors, quite obviously as has been suggested, the paraffin dehydrocyclization reaction w;ll predominate in the catalyst bed, or beds defining a zone located at the product exit side of the last reactor of the series. Often the paraffin dehydro-cyclization reaction is predominant of the sum-total of the reactions which occur within the catalyst bed, or beds constituting the last reactor of the series dependent upon the temperature and amount of catalyst that is employed in the final reactor vis-a-vis the total catalyst contained in the several reactors, and temperatures maintained in the other reactors of the reforming unit.
In one of its preferred aspects, promoted platinum, or platinum-rhenium catalyst is employed in the reforming zones in front of, or in adYance uf the paraffin dehydrocyclization zone, viz., the naphthene dehydrogenation zone, or zones, alnd the isomerization zone, or zones. Or, preferably also, an iridium promoted platinum, or platinum-ir;dium catalyst can be employed in the reforming zones in front of, or in advance of the paraffin dehydrocyclization zone, viz. the naphthene dehydrogenation zone, or zones, and the isomerization zone, or zones. Suitably, where a platinum-rhenium or platinum-iridium catalyst is employed, the weight ratio of the rhenium:platinum, or weight ratio of the iridium: platinum, respectively, will range from about 0.1:1 to about 1:1, preferably from about 0.5:1 to about 1:1, with the absolute concentration of the platinum ranging from about O.1 percent to about 1.0 percent, preferably from about 0.2 percent to about 0.7 percent, based on the total weight of the catalyst composition.
The catalyst employed in accordance with this invention is necessarily constituted of composite particles which contain, besides a 20~9~
support material, the hydrogenation-dehydrogenation components, a halide component and, preferably, the catalyst is sulf;ded. The support material is constituted of a porous, refractory inorganic oxide, particularly alumina. The support can contain, e.g., one or more alumina, bentonite, clay, diatomaceous earth, 7eolite, silica, activated carbon, magnesia, zirconia, thoria, and the like; though the most preferred support is alumina to wh;ch, if desired, can be added a suitable amount of other refractory carrier materials such as silica, zirconia, magnesia, t;tan;a, etc., usually in a range of about 1 to 20 percent, based on the weight of the support. A preferred support for the practice of the present invention is one having a surface area of more than 50 m2/g9 preferably from about 100 to about 300 m2/g, a bulk density nf about 0.3 to 1.0 g/ml, preferably about 0.4 to 0.8 g/ml, an average pore volume of about 0.2 to 1.1 ml/g, preferably about 0.3 to 0.8 ml/g, and an average pore diameter of about 30 to 300 Angstrom units.
The metal hydrogenation-dehydrogenation components can be uniformly dispersed throughout the porous inorganic oxide support by various techniques known to the art such as ion-exchange, coprecipi-tation with the alumina in the sol or glel form, and the like. For example, the catalyst composite can be formed by adding together suitable reagents such as a salt of tin, and ammonium hydroxide or carbonate, and a salt of aluminum such as aluminum chloride or aluminum sulfate to form aluminum hydroxide. The aluminum hydroxide containinq the tin salt can then be heated, dried, formed into pellets or extruded, and then calcined ;n air or n;trogen up to 540C. The other metal components can then be added. Suitably, the metal components can be added to the catalyst by impregnation, typically via an "incipient wetness" technique which requires a minimum of solution so that the total solution is absorbed, initially or after some evaporation.
It is preferred, in forming the catalysts of this invention, to deposit the t;n first, and the add;tional metals are then added to a previously pilled, pelleted, beaded, extruded, or sieved tin conta;n;ng particulate support mater;al by the ;mpregnation method. Pursuant to 20~19~
the impregnation method, porous refractory inorganic oxides in dry or solvated state are contacted, either alone or admixed, or otherwise incorporated with a metal or metals-containing solution, or solutions, and thereby impregnated by either the "incipient wetness" technique, or a technique embodying absorption from a dilute or concentrated solution, or solutions, with subsequent filtration or evaporation to effect total uptake of the metallic components which are uniformly dispersed throughout the particulate solids support.
In the step of forming the tin-containing support, a tin salt, e.g., stannous chloride, stannic chloride, stannic tartrate, stannic nitrate, or the like, can be uniformly dispersed throughout a solid support or carrier by the method described in U.S. Patent 4,963,249 which was issued on October 16, 1990 to William C. Baird, Jr. et al, specific reference being made to Column 6, lines 15 through 23, and Columns 58 through 69, inclusively, herewith incorporated and made of reference. In forming the lead reactor catalysts, the step of incorporating tin into the support is omitted, while other metallic components are added to the support by impregnation.
Platinum in absolute amount is usually supported on the carr~er within the range of from about 0.1 to about 1.0 percent, preferably from about 0.2 to about 0.7 percent, based on the weight of the catalyst (dry basis). Iridium, in absolute amount, is also usually supported on the carrier within the range of from about 0.1 to about 1.0 percent, preferably from about 0.2 to about 0.7 percent, based on the weight of the catalyst (dry basis). Rhenium, in absolute amount, where a platinum-rhenium catalyst is formed for use in the lead reactors, is also usually supported on the carrier in concentration ranging from about 0.1 to about 1.0 percent, preferably from about 0.2 to about 0.7 percent, based on the weight of the catalyst (dry basis). The tin, where added to the support to form the catalyst of this invent;on, preferably before addition of the platinum and iridium, is added to the support in concen~ration ranging from about 0.02 percent to about 0.4 percent, preferably from about 0.05 to about 0.3 percent, based on the total weight of the catalyst (dry basis). The weigh$ ratio of the 2~6 3 g~
(platinum ~ iridium):tin suitably ranges from about 2:1 ~o about 25:1, preferably from about 5:1 to about 15:1, based on he total weight of the platinum, iridium, and tin in the catalyst composition.
To enhance catalyst performance in reforming operations, it is also required to add a halogen component to the catalysts, fluorine and chlorine being preferred halogen components. The halogen is con-tained on the catalyst within the range of 0.1 to 3 percent, preferably within the range of about 0.8 to about 1.5 percent, based on the weight of the catalyst. When using chlorine as the halogen component, it is added to the catalyst within the range of about 0.2 to 2 percent, preferably within the range of about 0.8 to 1.5 percent, based on the weight of the catalyst. The introduction of halogen into the catalyst can be carried out by any method at any time. It can be added to the catalyst during catalyst preparation, for example, prior to, following or simultaneously with the incorporation oF a metal hydrogenation-dehydrogenation component, or components. It can also be introduced by contacting a carrier material in a vapor phase or liquid phase with a halogen compound such as hydrogen fluoride, hydrogen chloride, ammonium chloride, or the like.
The catalyst is dried by heating at a temperature above about 25C., preferably between about 65C. and 150C., in the presence o$ nitrogen or oxygen, or both, in an air stream or under vacuum. The catalyst is calcined at a temperature between about 200C. to 455C., either in the presenc~ of oxygen in an air stream or in the presence of an inert gas such as nitrogen.
Sulfur is a highly preferred component of the catalysts, the sulfur content of the catalyst generally ranging to about 0.2 percent, preferably from about 0.05 percent to about 0~15 percent, based on the weight of the catalyst (dry basis). The sulfur can be added to the catalyst by conventional methods, suitably by breakthrough sulfiding of a bed of the catalyst with a sulfur-containing gaseous stream, e.g., hydrogen sulfide in hydrogen, performed at temperatures ranging from about 175C. to about 565C.9 and at pressures ranging from about 1 to 2 ~ 9 ~
about 40 atmospheres for the time necessary to achieve breakthrough, or the desired sulfur level.
The feed or charge stock can be a virgin naphtha, cracked naphtha, a naphtha from a coal liquefaction process, a Fischer-Tropsch naphtha, or the like. Typical feeds are those hydrocarbons containing from about 5 to about 12 carbon atoms, or more preferably from about 6 to about 9 carbon atoms. Naphthas, or petroleum fractions boiling within the ranye of from about 25DC. to about 235~C., and preferably from about S0C. to about 190C., contain hydrocarbons of carbon numbers within these ranges. Typical fract;ons thus usually contain from about 15 to about 80 vol. % paraffins, both normal and branched, which fall in the range of about C5 to Cl2, from about 1~ to 80 vol. % of naphthenes falling within the range of from about C6 to C12, and from 5 through 20 vol. % of the desirable aromatics falling within the range of from about C6 to Cl2.
The reforming runs are initiated by adjusting the hydrogen and feed rates, and the temperature tEquivalent Isothermal Temperature) and pressure to operating conditions. The run is continued at optimum reforming conditions by adjustment of the major process variables, within the ranges described below:
Lead Reactor Condltions Major OperatingTypical Process Preferred Process VariablesConditions Condit;ons Pressure, psig 100-700 150-500 Reactor Temp., C. 370-540 425-510 Recycle Gas Rate, SCF/B 2000-10,000 2000-6000 Fced Rate, ~/Hr/W 1-20 2-10 ; Tail Reactor Conditions Major OperatingTypical Process Preferred Process Variabl esCond i t i on s Conditions Pressure, psig 100-700 150-500 Reactor Temp., C. 425-540 455-525 Recycle Gas Rate, SCF/B 2000-10,000 2000-6000 Feed Rate, W/Hr/W 1-10 2-8 2~56~6 The invention will be more fully understood by reference to the follow;ng comparative data illustrating its more salient features.
All parts are given in terms of weight except as otherwise specified.
The fsll DWi ng examples, and comparative demonstrations, are exemplary of the high activity, and selectivity of the catalysts of this invention; particularly, when employed in the paraffin dehydro-cyclization zone of the series of reaction zones while a different platinum catalyst is employed in the lead reaction zones. In the examples and demonstrations which follow all parts are in terms of weight units, pressures in terms of pounds per square inch gauge, and temperatures are given in Fahrenheit degrees except as otherwise expressed.
In conducting these tests, an n-heptane feed was used in certain instances. In others a full range naphtha was employed.
Inspect;ons on the fu11 range Arab Light Naphtha feed employed in making certain of the tests ar~ given below.
PropertY Arab Liqht Naphtha Gravity at 15C
Specific 0.7412 Octane, RON Clear 38 Molecular Weight 111.3 Sulfur, wppm 0-3 Distillation D-86, C
IBP 90.0 5% 102.5 10% 105.0 50O~o 125.0 90% 154.0 160.0 FBP 171.0 Composition, Wt. %
Total Paraffins 65.1 Total Naphthenes 19.3 Total Aromatics 15.6 2~$~
"
In a first series of runs, the performance of the platinum-iridium-tin catalysts of this invention was compared with a platinum-iridium (0.6% Pt/0.6% Ir) catalyst, a highly active catalyst, in reforming a heptane feed at 100 psig and 350 psig, respectively. The platinum-iridium catalysts were prepared by coimpregnation of l/lÇ inch diameter gamma alumina extrudates with an aqueous solution of chloro-plat;n;c acid and chloroiridic acid to uniformly disperse the metals throughout the extrudates, and this step was followed by drying, and calcination at 260C. The piatinum and iridium metal components of the platinum-iridium-tin catalysts were prepared in similar manner after forming alumina extrudates throughout which tin had been uniformly dispersed in amounts of 0.05% Sn, 0.1% Sn and 0.3% Sn, respectively, during preparation of the alumina support material.
The catalysts, after their preparation in this manner, were charged to capacity in a single reactor and heated to 400C. in air for three hours. Following three hours in air at 400C., the catalyst was heated to 455C., reduced with H2, and all of the catalysts, except one as indicated, were then sulfided with H2S in hydrogen at 455C. The heptane feed was then introduced ta a reactor in conducting a series of runs, respectively, a base run with the platinum-iridium catalyst, and runs with each of the catalysts modified with different concentrations, respectively, of the tin. The conditions of operation, and results achieved with each of the catalysts are given in Table lA (100 psig) and Table 1B (350 psig), respectively, as follows:
2 ~ 6 Table lA
HePtane Reformln~_at 100 DSiq 500C, 20 W/H/W, H2/Oil = 6 0.6% Pt/0.6% Ir with~ n 0.05/O Sn 0.1% Sn 0.3% Sn Sul f i ded Yes Yes Yes Yes Yield, Wt.%
Cl ~.4 2.3 2.1 1.6 i-~4 2.9 2.9 2.6 3.2 n-C4 6.4 6.0 6.3 5.3 Cs+ 75.9 77.3 77.9 79.4 Toluene 30.8 31.0 31.9 31.3 Conversion 70.0 71.4 72.6 66.1 Toluene Rate 6.3 6.4 6.5 6.4 Toluene Selectivity 44.3 43.4 44.1 47.4 Table lB
Heptane_Reforminq at 350 PS;q 480C, 80 W/H/W, H2/Oil - 3 0.6% Pt/0.6% Ir withni~ Sn 0.1% Sn 0.3% Sn 0.3% Sn (BASE) Sulfided Yes Yes Yes No Yield, Wt.~
Cl 2.5 2.1 1.1 3.2 i-C4 0.5 0.4 0.8 0.4 n-C, 9.9 9.2 6.2 5.8 C5~ ' 70.0 73O~ 82.6 79.3 Toluene 10.5 10 0 6.3 6.3 Conversion 52.0 46 4 33.8 38.3 Toluene Rate 8.4 8 0 5.1 6.5 Toluene Selectivity 20.4 21.7 18.7 17.2 These data, obtained by light product analyses over a four hour period, show that tin suppresses methane and ethane yields, and the C5~ liquid yield is considerably improved. Activity, as determined by conversion and toluene rate, compares well with the base case at 100 ps;g. At 350 psig however, 0.3% tin d;minishes the activity. The use of an unsulfided catalyst, used in an attempt to compensate for the diminished activity, produces excessive methane formation. A catalyst having 0.1% tin was found to increase the C5+ liquid yield with only a modest activity debit.
, i ,.... .
20~6196 In a second series of runs, a full range naphtha was reformed in recycle pilot plant runs over a catalyst charged to capacity in a single reactor, i.e., a tin modified platinum-iridium catalyst (0.6% Pt/0.6% Ir/0.1% Sn), and its performance compared in similar runs with known platinum-iridium catalysts which did not contain any tin, viz., Catalyst A ~0.6% Pt/0.6% Ir) and Catalyst B ~0.3% Pt/0.3% Ir). In conducting these runs, ten to twenty material balances were made over a period of several weeks and the results recorded and averaged. The results, and the conditions of operation, are given in Table 2.
Table 2 Naphtha Reforminn with Pt-Ir CatalYsts 470C-505C, 375 PSIG, 3500 SCF/B Recycle Gas, 4 W/H/W, H2/Oil = 2.5, RON = 100 A This invention B
(0.6% Pt/(0.6% Pt/0.6% Ir/ (0.3% ~t/
Catalyst 0.6% Ir) _ 0.1% Sn) 0.3% Ir) Relative Activity Number 310 260 220 Cs+ @ 100 RON, LV% 68.6 70.8 68.2 Wt.% @ 100 RON
H2 1.2 1.3 1.3 C1 6.2 5.4 5.9 C2 6.~ 5.4 6.0 C3 5.4 5.1 5.6 C4 6.~ 6.2 6~8 C5+ 74.8 76.5 74.2 These data clearly show that the tin modified platinum-;r;d;um catalyst of th;s ;nvention produces a 2.2 Vol.% Cs+
l;qu;d y;eld ;mprovement over a reform;ng operat;on conducted with Catalyst A, and a 2.6 Vol.% C5~ liquid yield ;mprovement over one conducted with Catalyst B~ The activity of the catalyst of this invention is only slightly less than that of Catalyst A.
...
.
2 ~ 9 ~
The following example, Example 3, simulates a staged reactor system wherein platinum-iridium catalysts are employed in the lead reactors of the series, and a tin-modified platinum-iridium catalyst is employed in the tail reactor of the series.
In a pair of additional runs, a full range naphtha was reformed in a simulated series of reactors at similar conditions except that in this instance, the front 45% of the reactor volume in each of the pair of runs was charged with a platinum-iridium (0.3% Pt/0.3% Ir) catalyst, i.e., Catalyst B as identified in Example 2, and the catalyst charged to the exit side of the reactor (rearward 55% of the reaotor volume) was ~1) a non-tin modified platinum-iridium (0.6% Pt/0.6% Ir) catalyst, Catalyst A as identified in Example 2, and (2) a tin modified platinum-iridium (0.6% Pt/0.6% Ir/Q.1% Sn) catalyst, a catalyst of this invention, as identified in Example 2. The results, and the conditions of operation, are given in Table 3.
Table 3 Naphtha Reforminq with Staqec! Pt-Ir CatalYsts 470C-505aC, 375 PSIG, 3500 SCF/B Recycle Gas, 4 W/H/W, H2/Oil = 2.5, RON = 100 Catalyst Loading Forward 45% B (0~3% Pt/0.3% Ir) B (0.3% Pt/0.3% Ir) Rearward 55% A (0.6% Pt/0.6% Ir) Catalyst of this Invention (0.6%
Pt/0.6% Ir/0.1% Sn) Relative Activity Number 290 250 C5~ @ 100 RON, LY% 68.0 70.0 Wt.% @ 100 RON
H2 1.2 1.4 Cl 6.3 5.1 C2 6.5 5.5 C3 6.0 5.8 c4 6.3 6.3 C5+ 74.5 76.1 - 2~6~
These data clearly demonstrate that the catalyst of this invention, employed in the dPhydrocyclization 70ne of the reactor, provides lower gas make and a 2.0 Vol.% C5+ liquid yield boost with only a modest activity loss.
The following example and comparative demonstratisns, like those described by reference to Example 1, demonstrate the selectivity advantages that can be obtained by the use of tin to modify the characteristirs of a platinum-iridium catalyst; differing from Example 1 in that the catalyst contains lesser amounts of the platinum and iridium metal components.
Example 1, and comparative demonstrations, were repeated, heptane being passed over, at 100 psig and 350 psig, respectively, a platinum-iridium (0.3% Pt/0.3% Ir) catalyst -- the base catalyst --, platinum-iridium catalysts modified with varying amounts of tin, viz., 0.05% Sn, 0.1% Sn and 0.3% Sn, respectively, and a platinum- rhenium catalyst charged to capacity in a single reactor. The conditions of operation, and the results obtained are given in Tables 4A and 4B, respectively.
Table 4A
HeDtane Reforminq at 100 psiq 500-C, 20 W/H/W, Hz/Oil = 6 0.3% Pt/0.3% Ir withnil Sn0.05% Sn0.1% Sn 0.3% Sn0.3%Pt/
(BASE) 0.7%Re Sulfided Yes Yes Yes Yes Yes Yield, Wt. %
Cl 1.8 1.8 1.5 1.4 0.9 i C4 2.8 3.0 ~.4 2.9 3.0 n-C4 5.0 4.9 4.4 4.1 4.1 C5~ 80.4 ~0.6 83.2 82.7 83.4 Toluene 29.0 27.2 25.9 27.8 20.5 Conversion 62.3 62.7 57.7 58 50.7 Toluene Rate 5.9 5.6 5.3 5.7 4.2 Toluene SelectiYity46.3 43.3 44.9 47.9 40.4 Table 4B
Heptane Reforminq at 350 p_~
480C, 80 W/H/W, H2/Oil = 3 0.3%Pt/0.3%Ir nil Sn 0.05%Sn0.1%Sn 0.3%Sn 0.3%Sn Pt/Re with (BASE) 0.3%/0.7%
Sulfided Yes Yes Yes Yes No Yes Yield, Wt.%
Cl 1.3 1.1 n.s 0.6 305 0.3 i-C4 1.0 1.1 0.7 0.8 U.5 0.$
n-C4 7.9 6.9 5.5 4.3 6.3 2.0 C5+ 79.1 81.8 85.7 88.6 77.7 94.6 Toluene 10.1 8.7 7.1 6.7 5.7 4.2 Conversion 46.3 41.5 31.8 26.4 42.5 13.3 Toluene Rate 8.1 7.0 5.7 5.4 4.3 3.3 Toluene Selectivity 21.8 21.0 22.4 25.5 13.5 31.1 These data clearly show that the iridium modifier added to platinum provides a higher conversion and toluene rate than rhenium.
Normally however this increased activity is accompanied by lower Cs+
liquid yields caused by excessive metals dealkylation. The use of tin as a modifier suppresses iridium metal dealkylation, permitting higher C5+ liquid yields than a non-tin modified platinum-iridium catalyst. On the other hand, whereas some activity is lost by the platinum-iridium catalyst as a result ~f the added tin, the activity loss is very modest. Tin suppresses methane and ethane yields when added in small, and infinitesimal amount to platinum-iridium catalysts, as shown by these data, but yet the activity of the tin modified platinum-iridium catalysts is still super;or to conventional plat;num-rhenium catalysts.
Tin added to the platinum-iridium catalyst has a pronounced Cs+ liquid yield benefit at higher pressure.
Staged platinum-rhenium catalysts are currently widely employed as high pressure reforming catalysts in commercial reforming units. The reactors in these units are filled to capacity with the catalyst, and the octane barrel production is constrained by the ac$ivity of the platinum-rhenium catalysts. Increasing octane demand provides strong incent;ves for catalysts with higher activity than the :
.. ~ .
~5~
commerc;al platinum-rhenium catalysts at equivalent C5+ l;quid yield.
The catalyst of this invention, as demonstrated by the following example, can provide higher act;vity with C5+ liquid yield equivalent to the platinum-rhenium catalysts. Replacing, e.g., a presently used 0.3%
Pt/0.7% Re catalyst with a tin modif;ed platinum-ir;dium (0.3% Pt/0.3%
Ir) catalyst ean give a significant act;vity boost without yield debit, as shown by the following data.
A full range naphtha feed was reformed in parallel runs, at similar cond;tions, in a reactor the forward 45% of the available reactor space of which contained a platinum-rhenium (0.3% Pt/0.3% Re) catalyst, Catalyst C, and the rearward 55% of the available reactor space of wh;ch, in a f;rst run was packed with (1) a platinum-rhenium (0.3% Pt/0.7% Re) catalyst, Catalyst D, and, in a second run, (2) with a tin modified platinum-;r;d;um (0.3/0 Pt/0.3% Ir/0.1% Sn) catalyst, a catalyst of th;s ;nvent;cn.
Table 5 Naphtha Reforminq with Staqed Pt-Re~Pt-Ir Catalvsts 470C-525C, 375 PSIG, 2 W/H/W, 3.5 kSCF/B Recycle, H2/Oil 5 2.5, RON - 100 Catalyst Forward 45%C(0.3%Pt/0.3%Re) C(0.3%Pt/0.3%Re) Rearward 55%D(0.3%Pt/0.7%Re~ 0~3%PtJO.3%Ir/0.1%Sn Relative Activity 60 120 C + ~ 100 RON, LV% 69 70 .% @ 100 RON
H21.4 1.4 Cl2.7 3.7 C25.5 5.3 C37.5 6.3 C48.3 7.6 C5+ 74.5 7~.6 These data thus show a profound increase in activity using the tin modifi~d platinum-iridium catalyst of this invention in the 2 ~ 6 hydrodecyclization zone, or exit s;de of the reactor. Thus, the activity of the tin modified platinum-ir;d;um catalyst used only in the rearward side of the reactor space doubled the activity of the total catalyst used in the system, and reduced gas make as well as having increased the C5+ liquid yield by 1.0 Vol.%. In addition, this catalyst has been found to temper temperature runaway rates during process upsets as contrasted with conventional platinum-iridium catalysts.
It is apparent that various modifications and changes can be made without departing the spirit and scope of the invention.
Claims (9)
1. A catalyst composition useful for improving the octane quality of a naphtha by reforming said naphtha at reforming conditions which comprises from about 0.1 percent to about 1.0 percent platinum, from about 0.1 percent to about 1.0 percent iridium, and from about 0.02 percent to about 0.4 percent tin, composited with and uniformly dispersed throughout an inorganic oxide support.
2. The composition of Claim 1 wherein the composite contains from about 0.2 percent to about 0.7 percent platinum, from about 0.2 percent to about 0.7 percent iridium, and from about 0.05 to about 0.3 percent tin.
3. The composition of Claim 1 wherein the composite contains from about 0.1 percent to about 3.0 percent halogen, and from about 0.01 percent to about 0.2 percent sulfur.
4. The composition of Claim 1 wherein the inorganic oxide support is alumina.
5. The composition of Claim 1 wherein the catalyst composite contains a weight ratio of (platinum + iridium):tin ranging from about 2:1 to about 25:1.
6. A process for improving the octane quality of a naphtha in a reforming unit comprised of a plurality of serially connected reactors inclusive of one or more lead reactors and tail reactors, each of which contains a platinum supported catalyst the naphtha flowing in sequence from one reactor of the series to another and contacting the catalyst at reforming conditions in the presence of hydrogen, wherein one or more of the reactors contains a tin containing catalyst comprised of:
from about 0.1 percent to about 1.0 percent platinum, from about 0.1 percent to about 1.0 percent iridium, and from about 0.02 percent to about 0.4 percent tin, composited with and uniformly dispersed throughout an inorganic oxide support.
from about 0.1 percent to about 1.0 percent platinum, from about 0.1 percent to about 1.0 percent iridium, and from about 0.02 percent to about 0.4 percent tin, composited with and uniformly dispersed throughout an inorganic oxide support.
7. The process of Claim 6 wherein the catalyst contains from about 0.2 percent to about 0.7 percent platinum, from about 0.2 percent to about 0.7 percent iridium, and from about 0.05 to about 0.3 percent tin, and from about 0.1 percent to about 3.0 percent halogen;
and from about 0.01 percent to about 0.2 percent sulfur.
and from about 0.01 percent to about 0.2 percent sulfur.
8. The process of claim 6 wherein only the tail reactor contains said tin containing catalyst.
9. The process of claim 8 wherein the lead reactor contains a catalyst comprised of (a) about 0.1 percent to about 1.0 percent platinum, and from abut 0.1 percent to about 1.0 percent rhenium; or 0.1 percent to about 1.0 percent iridium.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/627,528 US5106809A (en) | 1990-12-14 | 1990-12-14 | High activity, high yield tin modified platinum-iridium catalysts, and reforming process utilizing such catalysts |
| US627,528 | 1990-12-14 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2056196A1 true CA2056196A1 (en) | 1992-06-15 |
Family
ID=24515028
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002056196A Abandoned CA2056196A1 (en) | 1990-12-14 | 1991-11-26 | High activity, high yield tin modified platinum-iridium catalysts, and reforming process utilizing such catalysts |
Country Status (4)
| Country | Link |
|---|---|
| US (1) | US5106809A (en) |
| EP (1) | EP0490695A1 (en) |
| JP (1) | JPH04277028A (en) |
| CA (1) | CA2056196A1 (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA2030345C (en) * | 1989-11-22 | 1998-12-08 | Ryuji Ueno | Use of 15-keto-prostaglandin compound for improvement of encephalic function |
| FR2789332B1 (en) | 1999-02-09 | 2001-04-13 | Inst Francais Du Petrole | HOMOGENEOUS CATALYST BED AND PROCESS FOR CONVERTING HYDROCARBONS INTO AROMATIC COMPOUNDS WITH SAID BED |
| US6392109B1 (en) * | 2000-02-29 | 2002-05-21 | Chevron U.S.A. Inc. | Synthesis of alkybenzenes and synlubes from Fischer-Tropsch products |
| FR2840548B1 (en) * | 2002-06-07 | 2005-03-18 | Inst Francais Du Petrole | HOMOGENEOUS CATALYST BED AND PROCESS FOR PROCESSING HYDROCARBONS INTO AROMATIC COMPOUNDS WITH SUCH BED |
| EP1753532A1 (en) * | 2004-05-14 | 2007-02-21 | Dow Gloval Technologies Inc. | High selectivity catalyst for the conversion of carbon tetrachloride to chloroform |
| MX2011006487A (en) * | 2008-12-18 | 2011-09-30 | Uhde Gmbh | Variation of the tin impregnation of a catalyst for the dehydrogenation of alkanes. |
Family Cites Families (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2130881A6 (en) * | 1969-02-14 | 1972-11-10 | Raffinage Cie Francaise | Hydroreforming catalyst |
| US3718578A (en) * | 1970-02-20 | 1973-02-27 | Chevron Res | Reforming with a platinum-tin-iridium catalyst |
| US3702294A (en) * | 1971-05-10 | 1972-11-07 | Universal Oil Prod Co | Trimetallic hydrocarbon conversion catalyst and uses thereof |
| US4212770A (en) * | 1979-03-22 | 1980-07-15 | Uop Inc. | Acidic multimetallic catalytic composite |
| FR2560205B1 (en) * | 1984-02-23 | 1988-07-15 | Inst Francais Du Petrole | CATALYTIC REFORMING PROCESS |
| FR2593824B1 (en) * | 1986-02-03 | 1988-11-04 | Inst Francais Du Petrole | CATALYTIC REFORMING PROCESS THROUGH AT LEAST THREE CATALYST BEDS |
| FR2611740B2 (en) * | 1986-04-16 | 1989-10-27 | Inst Francais Du Petrole | CATALYTIC REFORMING PROCESS |
| US4714539A (en) * | 1986-09-22 | 1987-12-22 | Uop Inc. | Reforming of hydrocarbons utilizing a trimetallic catalyst |
| US4714538A (en) * | 1986-09-22 | 1987-12-22 | Uop Inc. | Trimetallic reforming catalyst |
| US4714540A (en) * | 1986-09-22 | 1987-12-22 | Uop Inc. | Reforming of hydrocarbons utilizing a trimetallic catalyst |
| US4737483A (en) * | 1986-09-22 | 1988-04-12 | Uop Inc. | Trimetallic reforming catalyst |
| US4677094A (en) * | 1986-09-22 | 1987-06-30 | Uop Inc. | Trimetallic reforming catalyst |
-
1990
- 1990-12-14 US US07/627,528 patent/US5106809A/en not_active Expired - Fee Related
-
1991
- 1991-11-26 CA CA002056196A patent/CA2056196A1/en not_active Abandoned
- 1991-12-12 EP EP91311603A patent/EP0490695A1/en not_active Withdrawn
- 1991-12-16 JP JP3332130A patent/JPH04277028A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| JPH04277028A (en) | 1992-10-02 |
| US5106809A (en) | 1992-04-21 |
| EP0490695A1 (en) | 1992-06-17 |
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