United States Patent c191
`Foutsitzis et al.
`
`[11] Patent Number:
`[45] Date of Patent:
`
`5,035,792
`Jul. 30, 1991
`
`[54] CLEANUP OF
`HYDROCARBON-CONVERSION SYSTEM
`
`[75]
`
`Inventors: Arthur A. Foutsitzis, Worcester,
`Mass.; Frank G. Padrta, Des Plaines;
`Michael B. Russ, Elmhursti both of
`Ill.
`[73] Assignee: UOP, Des Plaines, Ill.
`[21] Appl. No.: 615,105
`[22] Filed:
`Nov. 19, 1990
`Int. ct.s .............................................. ClOG 35/09
`[51]
`[52] U.S. Cl ..................................... 208/138; 208/134;
`134/22.1; 134/22.12; 134/22.14
`[58] Field of Search ............ 208/138; 134/22.l, 27.11,
`134/22.12, 27.14
`
`. [56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`2,662,041 12/1953 Dougherty et al. ............... 134/22.1
`2,873,176 2/1959 Hengstebeck ......................... 23/288
`3,137,646 6/1964 Capsuto ................................ 208/65
`
`3,567,627 3/1971 Feferle ................................ 208/138
`3,732,123 S/1973 Stolfa et al ............................ 134/19
`4,155,836 S/1979 Collins ................................ 208/139
`4,329,220 S/1982 Nelson ................................ 208/138
`4,456,527 6/1984 Buss et al .............................. 208/89
`4,507,397 3/1985 Buss ...................................... 502/38
`4,925,544 5/1990 Robinson et al .................... 208/138
`4,940,532 7/1990 Peer et al ............................ 208/138
`Primary Examiner-Helane E. Myers
`Attorney, Agent, or Firm-Thomas K. McBride; John F.
`Spears, Jr.; Richard E. Conser
`ABSTRACT
`[57]
`A hydrocarbon solvent is utilized to purge contami(cid:173)
`nants, such as sulfur, from a conversion system. Com(cid:173)
`plementary contaminant-removal steps may include
`oxidation, reduction, and contaminant removal with a
`sacrificial particulate bed. This solvent purge avoids
`deactivation of a subsequently loaded contaminant-sen(cid:173)
`sitive catalyst, such as a reforming catalyst selective for
`dehydrocyclization.
`
`17 Claims, No Drawings
`
`Page 1 of 7
`
`ULI EXHIBIT 1003
`
`

`

`1
`
`5,035,792
`
`2
`acidizing do not provide the completeness of sulfur
`removal required. Therefore, an exceptionally effective
`cleanup method is needed for these existing units as a
`concomitant to the reforming process for paraffin dehy-
`5 drocyclization.
`3. Related Art
`Techniques are known in the art for avoiding deacti-
`vation of reforming catalysts by sulfur oxides produced
`from sulfur scale on the equipment during catalyst re(cid:173)
`generation. U.S. Pat. No. 2,873,176 (Hengstebeck) dis(cid:173)
`closes avoidance of an oxidizing atmosphere in equip-
`ment, other than reactors, which has been exposed to
`sulfur in the feedstock in order to avoid injury to the
`catalyst. U.S. Pat. No. 3,137,646 (Capsuto) teaches
`purging of sulfur from the lead heater of a catalytic
`reforming unit to the heater stock until S02 is not de-
`tected to avoid deterioration of the catalyst. U.S. Pat.
`No. 4,507,397 (Buss) reveals that controlling the water
`content of a regenerating gas to no more than 0.1 mol %
`in a catalytic reforming unit having sulfur-contaminated
`vessels avoids reaction of sulfur oxides with the cata-
`lyst. The above patents relate to protecting a reforming
`catalyst from sulfur scale during regeneration, in con(cid:173)
`trast to the present invention which addresses the need
`to remove contaminants evolved during process opera(cid:173)
`tion.
`U.S. Pat. No. 4,155,836 (Collins, et al.) discloses that
`sulfur-contaminated reforming catalyst may have its
`activity restored by discontinuing the hydrocarbon feed
`and passing hydrogen and halogen over the catalyst to
`reduce its sulfur concentration. U.S. Pat. No. 4,456,527
`(Buss, et al.) teaches that a variety of sulfur-removal
`options may be used to reduce the sulfur content of a
`hydrocarbon feed to as low as 50 parts per billion for
`dehydrocyclization over a catalyst with high sulfur
`sensitivity. Buss, et al. thus recognizes the need for
`exceedingly low sulfur to a reforming catalyst selective
`for dehydrocyclization. Neither of the above refer-
`ences, however, contemplates the use of a hydrocarbon
`solvent to purge contaminants from a prior-con(cid:173)
`taminated conversion system. U.S. Pat. No. 3,732,123
`(Stolfa et al.) teaches a method of descaling a heater
`contaminated with sulfurous and nitrogenous com-
`pounds by alternate oxidation and reduction techniques.
`U.S. Pat. No. 4,940,532 (Peer et al.) discloses the use
`and replacement of a sacrificial particulate bed to re(cid:173)
`move contaminants from a catalytic-reforming system.
`Peer does not contemplate the combination of purging
`contaminants from the equipment of a conversion sys(cid:173)
`tem using a hydrocarbon solvent and subsequently
`using a contaminant-sensitive catalyst for hydrocarbon
`conversion, however.
`
`CLEANUP OF HYDROCARBON-CONVERSION
`SYSTEM
`
`10
`
`BACKGROUND OF THE INVENTION
`1. Field of the Invention
`This invention relates to an improved process for the
`conversion of hydrocarbons, and more specifically for
`the catalytic reforming of gasoline-range hydrocarbons.
`2. General Background
`The catalytic reforming of hydrocarbon feedstocks in
`the gasoline range is an important commercial process,
`practiced in nearly every significant petroleum refinery
`in the world to produce aromatic intermediates for the
`petrochemical industry or gasoline components with 15
`high resistance to engine knock. Demand for aromatics
`is growing more rapidly than the supply of feedstocks
`for aromatics production. Moreover, the widespread
`removal of lead antiknock additive from gasoline and
`the rising demands of high-performance internal-com- 20
`bustion engines are increasing the required knock resis(cid:173)
`tance of the gasoline component as measured by gaso(cid:173)
`line "octane" number. The catalytic reforming unit
`therefore must operate more efficiently at higher sever(cid:173)
`ity in order to meet these increasing aromatics and gaso- 25
`line-octane needs. This trend creates a need for more
`effective reforming catalysts for application in new and
`existing process units.
`Catalytic reforming generally is applied to a feed(cid:173)
`stock rich in paraffinic and naphthenic hydrocarbons 30
`and is effected through diverse reactions: dehydrogena(cid:173)
`tion of naphthenes to aromatics, dehydrocyclization of
`paraffins, isomerization of paraffins and naphthenes,
`dealkylation of alkylaromatics, hydrocracking of paraf(cid:173)
`fins to light hydrocarbons, and formation of coke which 35
`is deposited on the catalyst. Increased aromatics and
`gasoline-octane needs have turned attention to the
`paraffin-dehydrocyclization reaction, which is less fa(cid:173)
`vored thermodynamically and kinetically in conven(cid:173)
`tional reforming than other aromatization reactions. 40
`Considerable leverage exists fo.r increasing desired
`product yields from catalytic reforming by promoting
`the dehydrocyclization reaction over the competing
`hydrocracking reaction, thus producing a higher yield
`of aromatics and a lower output of fuel gas, while mini- 45
`mizing the formation of coke.
`The effectiveness of reforming catalysts comprising a
`non-acidic L-zeolite and a platinum-group metal for
`dehydrocyclization of paraffins is well known in the art.
`The use of these reforming catalysts to produce aromat- 50
`ics from paraffinic raffinates as well as naphthas has
`been disclosed. The increased sensitivity to feed sulfur
`of these selective catalysts also is known. However, this
`dehydrocyclization technology has not been commer(cid:173)
`cialized during the intense and lengthy development 55
`period. The extreme catalyst sulfur intolerance is be(cid:173)
`lieved to be the principal reason for this delay in com(cid:173)
`mercialization. This catalyst may be deactivated rapidly
`in an existing reforming unit whicli previously em(cid:173)
`ployed a less-sulfur-sensitive catalyst for conversion of 60
`a sulfur-containing feed, since traces of sulfur contami(cid:173)
`nation may remain in the process equipment even after
`conventional cleanup of the equipment. If the effect of
`sulfur contamination could be eliminated, existing re(cid:173)
`forming units could be reassigned for paraffin dehydro- 65
`cyclization operations as large modern naphtha reform(cid:173)
`ing units are constructed in conjunction with refinery
`modernizations. Conventional oxidation, reduction and
`
`SUMMARY OF THE INVENTION
`It is an object of the present invention to provide a
`hydrocarbon-conversion process for the effective use of
`a contaminant-sensitive catalyst in an existing system
`having contaminated equipment. A more specific objec(cid:173)
`tive is to obtain extended catalyst life for a dehydrocy(cid:173)
`clization used in an existing catalytic reforming system.
`This invention is based on the discovery that sulfur
`contaminants surprisingly are purged from contami(cid:173)
`nated equipment in a catalytic reforming system by
`contact with a hydrocarbon solvent, enabling the use of
`a contaminant-sensitive catalyst in the system.
`A broad embodiment of the present invention is a
`hydrocarbon-conversion process using a hydrocarbon
`
`Page 2 of 7
`
`ULI EXHIBIT 1003
`
`

`

`3
`solvent to purge contaminants, which result from the
`prior processing of a contaminant-containing feed, from
`a conversion system followed by the loading and use of
`a contaminant-sensitive catalyst in the system.
`In a preferred embodiment, the contaminant is sulfur.
`In a highly preferred embodiment, the hydrocarbon(cid:173)
`conversion process is catalytic reforming and the equip(cid:173)
`ment is freed of sulfur in order to use a sulfur-sensitive
`catalyst effective for the dehydrocyclization of paraf(cid:173)
`fins. In an especially preferred embodiment, the hydro(cid:173)
`carbon solvent comprises principally aromatic hydro(cid:173)
`carbons.
`These as well as other objects and embodiments will
`become apparent from the detailed description of the
`invention.
`
`DESCRIPTION OF THE PREFERRED
`EMBODIMENTS
`To reiterate, a broad embodiment of the present in(cid:173)
`vention is a hydrocarbon-conversion process using a 20
`hydrocarbon solvent to purge contaminants, which
`result from the prior processing of a contaminant-con(cid:173)
`taining feed, from a conversion system followed by the
`loading and use of a contaminant-sensitive catalyst in
`the system.
`The conversion system of the present invention is an
`integrated processing unit which includes equipment,
`catalyst, sorbents and chemicals used in the processing
`of a hereinafter-defined hydrocarbon feedstock. The
`equipment includes reactors, reactor internals for dis- 30
`tributing feed and containing catalyst, other vessels,
`heaters, heat exchangers, conduits, valves, pumps, com(cid:173)
`pressors and associated components known to those of
`ordinary skill in the art. Preferably, the conversion
`system is a catalytic-reforming system.
`The conversion system comprises either a fixed-bed
`reactor or a moving-bed reactor whereby catalyst may
`be continuously withdrawn and added. These alterna(cid:173)
`tives are associated with catalyst-regeneration options
`known to those of ordinary skill in the art, such as: (1) 40
`a semiregenerative unit containing fixed-bed reactors,
`which maintains operating severity by increasing tem(cid:173)
`perature, eventually shutting the unit down for catalyst
`regeneration and reactivation; (2) a swing-reactor unit,
`in which individual fixed-bed reactors are serially iso- 45
`lated by manifolding arrangements as the catalyst be(cid:173)
`comes deactivated and the catalyst in the isolated reac(cid:173)
`tor is regenerated and reactivated while the other reac(cid:173)
`tors remain on-stream; (3) continuous regeneration of
`catalyst withdrawn from a moving-bed reactor, with 50
`reactivation and substitution of the reactivated catalyst,
`which permits higher operating severity by maintaining
`high catalyst activity through regeneration cycles of a
`few days; or, (4) a hybrid system with semiregenerative
`and continuous-regeneration provisions in the same 55
`unit. The preferred embodiment of the present inven(cid:173)
`tion is fixed-bed reactors in a semiregenerative unit.
`The feed to the conversion system may contact the
`respective particulate bed or catalyst in the reactors in
`either upflow, downflow, or radial-flow mode. Since 60
`the preferred dehydrocyclization reaction is favored by
`relatively low pressure, the low pressure drop in a radi(cid:173)
`al-flow reactor favors the radial-flow mode.
`The contaminants comprise elements other than car(cid:173)
`bon or hydrogen, especially sulfur, nitrogen, oxygen or 65
`metals, which were deposited on the equipment of the
`conversion system in a precedent conversion process
`effected in the conversion system on a contaminant-
`
`5,035,792
`
`4
`containing prior feed previous to the execution of the
`present invention. A preferred example is sulfur intro(cid:173)
`duced into the conversion system as sulfur compounds
`in a sulfur-containing prior feed to a precedent conver-
`5 sion process. As is well known, sulfur compounds de(cid:173)
`composed in the precedent conversion operation may
`result in formation of metal sulfides, e.g., by reaction of
`hydrogen sulfide with internal surfaces of such equip(cid:173)
`ment as heaters, reactors, reactor internals and conduits.
`IO Sulfur may be released from such sulfides especially in
`a reforming process, forming hydrogen sulfide which
`joins the process reactants when processing a contami(cid:173)
`nant-free feed reformer feed.
`The nature of equipment contamination from the
`15 processing of a contaminant-containing prior feed
`which leads to the surprising results of the present in(cid:173)
`vention is not well known. Sulfur contamination, for
`example, may result from reaction products which re-
`main on the equipment of a catalytic-reforming system.
`It is believed, without limiting the invention thereby,
`that highly condensed, insoluble aromatic compounds
`can be formed while processing the prior feed by con(cid:173)
`densation of small amounts of higher-boiling, sulfur(cid:173)
`containing, higher-boiling components of the prior feed.
`25 These insoluble compounds may not be entirely re(cid:173)
`moved by the process reactants, but may instead accu(cid:173)
`mulate on the equipment. When a contaminant-sensitive
`catalyst such as a dehydrocyclization catalyst subse-
`quently is loaded into the catalytic-reforming system,
`small amounts of the highly condensed aromatic com(cid:173)
`pounds may desorb from the equipment and result in
`catalyst deactivation. Purging of this condensed mate(cid:173)
`rial from the system may also purge sulfur compounds,
`resulting in the surprising benefits of the present inven-
`35 tion.
`The amount of sulfur released during operation with
`a contaminant-sensitive catalyst may be minor relative
`to the reactants, particularly if the feed to the prior
`conversion process had been desulfurized or if the con(cid:173)
`version system has been acidized or cleaned by other
`known chemical treatments prior to use in the process
`of the present invention. However, it has now been
`found that even minor amounts of sulfur can deactivate
`a catalyst selective for dehydrocyclization of paraffins,
`such as the sulfur-sensitive reforming catalyst described
`hereinafter.
`In the present invention, the contaminants are purged
`from the conversion system by introducing a hydrocar(cid:173)
`bon solvent into the system at contaminant-purging
`conditions. These conditions are determined by the
`nature of the solvent and comprise a pressure of from
`about atmospheric to 100 atmospheres, preferably at(cid:173)
`mospheric to 50 atmospheres, and a temperature of
`from about 10° to 400' C. In a preferred embodiment,
`the solvent is at conditions near its critical region. The
`conversion system may be loaded with solvent more
`than once, withdrawing a load of solvent containing
`purged contaminants and loading contaminant-free sol(cid:173)
`vent in order to purge the contaminants from the system
`more completely. The solvent preferably is circulated
`through the system such as by pumping, in order to
`obtain more effective contact with contaminated equip(cid:173)
`ment surfaces. In an alternative embodiment, inert gases
`are circulated along with the solvent to improve
`contact between solvent and equipment. The gases are
`inert to reaction with the solvent or contaminant, nitro-
`gen and hydrogen being preferred gases and nitrogen
`being especially preferred.
`
`Page 3 of 7
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`ULI EXHIBIT 1003
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`

`

`5,035,792
`
`s
`6
`tive catalyst within a three-month period of operation.
`In an especially preferred embodiment, circulating
`Preferably the level of contaminant will be below de-
`solvent contacts a contaminant sorbent to remove con-
`tectable levels, by test methods known in the art, when
`taminants from the solvent. Excellent results have been
`the conversion system is contaminant-free. A preferred
`obtained when manganese oxide is used as a sulfur sor-
`5 embodiment comprises a sulfur-free catalytic-reforming
`bent to remove sulfur from circulating solvent.
`system, wherein sulfur is below detectable limits in the
`The solvent used for contaminant purging in the
`reactants of the catalytic-reforming system.
`present invention comprises, and preferably consists
`Each of the hydrocarbon feed and the sacrificial feed
`essentially of, hydrocarbons. Non-hydrocarbon sol-
`comprises paraffins and naphthenes and may comprise
`vents are not recommended, and might in some cases
`hllve an adverse effect on the catalyst which subse- 10 olefins and mono- and polycyclic aromatics. The pre-
`ferred feed boils within the gasoline range and may
`quently is loaded into the system. A solvent comprising
`principally aromatic hydrocarbons has been found to be
`comprise gasoline, synthetic naphthas, thermal gasoline,
`effective in the decontamination step of the present
`catalytically cracked gasoline, partially reformed naph-
`thas or raffinates from extraction of aromatics. The
`process. Catalytic reformate having an aromatics con-
`tent of over 50 volume % is widely available and gener- 15 distillation range may be that of a full-range naphtha,
`having an initial boiling point typically from 40° -80° C.
`ally is suitable. An aromatic concentrate which may
`comprise toluene, Cs aromatics and/or C9+ aromatics
`and a final boiling point of from about 150°-210° C., or
`is particularly effective in the present process. Solvent
`it may represent a narrower range within these broad
`ranges. Paraffinic stocks, such as naphthas from Middle
`withdrawn from the system which contains purged
`contaminants may be processed in conventional refining 20 East crudes, are especially preferred hydrocarbon feeds
`due to the ability of the process to dehydrocyclize par-
`equipment, such as by distillation, to separate the con-
`taminants.
`affins to aromatics. Raffinates from aromatics extrac-
`lt is within the scope of the present invention that the
`tion, containing principally low-value C6-Cs paraffins
`process include one or more of known oxidation, reduc-
`which can be converted to valuable B-T-X aromatics;
`tion and acidizing steps. These steps are particularly 25 are especially preferred.
`Each of the hydrocarbon feed and the sacrificial feed
`effective in removing the sulfide scale mentioned here-
`inabove. Descaling as applied to heater tubes, where the
`are substantially contaminant-free. Substantially con-
`problem generally is most severe, is taught in U.S. Pat.
`taminant-free is defined as a level of contaminant that, in
`No. 3,732,123,
`incorporated herein by
`reference
`the hydrocarbon feed, would not cause a shut down of
`thereto. These known steps may be incorporated into 30 the conversion system due to the deactivation of the
`contaminant-sensitive catalyst within a three-month
`the process before or after the solvent decontamination
`of the present invention, but preferably after the solvent
`period of operation. Preferably the level of contaminant
`contaminant-purging step.
`will be below detectable levels, by test methods known
`It also is within the scope of the invention to contact
`in the art. Each of the first hydrocarbon feed and the
`a sacrificial feed with a sacrificial particulate bed to 35 hydrocarbon feed preferably has been treated by con-
`ventional methods such as hydrotreating, hydrorefining
`remove contaminants, preferably after the solvent-
`or hydrodesulfurization to convert sulfurous, nitroge-
`decontamination step. According to this alternative
`solvent purging removes the bulk, or most, of the con-
`nous and oxygenated compounds to H2S, NH3 and
`taminants and the sacrificial feed and particulate bed
`H20, respectively, which can be separated from the
`remove the remaining contaminants to provide a con- 40 hydrocarbons by fractionation. This conversion prefer-
`ably will employ a catalyst known to the art comprising
`taminant-free system. The sacrificial feed preferably is
`substantially contaminant-free as defined hereinafter. In
`an inorganic oxide support and metals selected from
`Groups VIB (6) and VIII (9-10) of the Periodic Table.
`the preferred catalytic-reforming system at catalytic-
`reforming conditions, sulfur is released from equipment
`[See Cotton and Wilkinson, Advanced Organic Chemis-
`surfaces at sulfur-removal conditions. By contacting the 45 try, John Wiley & Sons (Fifth Edition, 1988)]. Alterna-
`tively or in addition to the conversion step, the feed
`sacrificial particulate bed, sulfur released from equip-
`ment surfaces is either converted to a form more easily
`may be contacted with sorbents capable of removing
`removable in the effluents from the conversion system,
`sulfurous and other contaminants. These sorbents may
`deposited on the particulate bed, or both converted and
`include but are not limited to zinc oxide, nickel-alumina,
`deposited on the bed. In a preferred embodiment, sulfur 50 nickel-clay, iron sponge, high-surface-area sodium,
`high-surface-area alumina, activated carbons and mo-
`released from the equipment is converted to hydrogen
`sulfide by contact with a sacrificial reforming catalyst
`lecular sieves. Best results are obtained when manga-
`and the hydrogen sulfide is removed from the system by
`nese oxide, especially a manganous oxide, is employed
`as a sorbent. This sulfur sorbent may be identical to the
`contact with a manganese oxide sorbent. The sacrificial
`particulate bed is removed from the conversion system 55 sulfur sorbent employed for contaminant removal from
`the solvent as described hereinbefore.
`when contaminant removal is substantially complete
`and the conversion system thus is contaminant-free.
`In the preferred catalytic-reforming system, sulfur-
`Further details of this optional step are contained in
`free hydrocarbon feeds have low sulfur levels disclosed
`U.S. Pat. No. 4,940,532, incorporated herein by refer-
`in the prior art as desirable reforming feedstocks, e.g., 1
`60 ppm to 0.1 ppm (100 ppb). Most preferably, the hydro-
`ence.
`Contaminant purging is measured by testing the efflu-
`carbon feed contains no more than 50 ppb sulfur.
`The contaminant-sensitive catalyst is loaded into the
`ent streams from the conversion system for contaminant
`levels using test methods known in the art. Contaminant
`conversion system after contaminants have been purged
`purging is substantially complete and the system is con-
`and the system is substantially contaminant-free. The
`taminant free when the measured level of contaminant, 65 contaminant-sensitive catalyst contacts the hydrocar-
`bon feed at hydrocarbon-conversion conditions. Hy-
`if contained in the hydrocarbon feed as defined herein-
`after, would not cause a shut down of the conversion
`drocarbon-conversion conditions comprise a pressure
`system due to the deactivation of the contaminant-sensi-
`of from about atmospheric to 150 atmospheres (abs), a
`
`Page 4 of 7
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`

`5,035,792
`
`7
`temperature of from about 200° to 600° C., and a liquid
`hourly space velocity relative to the contaminant-sensi(cid:173)
`tive catalyst of from about 0.2 to 10 hr- I. Preferably
`the system is a sulfur-free catalytic-reforming system
`and the conditions comprise reforming conditions in- 5
`eluding a pressure of from about atmospheric to 60
`atmospheres (abs). More preferably the pressure is from
`atmospheric to 20 atmospheres (abs), and excellent re(cid:173)
`sults have been obtained at operating pressures of less
`than 10 atmospheres. The hydrogen to hydrocarbon 10
`mole ratio is from about 0.1 to 10 moles of hydrogen per
`mole of hydrocarbon feed. Space velocity with respect
`to the volume of contaminant-sensitive catalyst is from
`about 0.5 to 10 hr-I. Operating temperature is from
`about 400° to 560° C. Since the predominant reaction of 15
`the preferred embodiment is the dehydrocyclization of
`paraffins to aromatics, the contaminant-sensitive cata(cid:173)
`lyst will preferably be contained in two or more reac(cid:173)
`tors with interheating between reactors to compensate
`for the endothermic heat of reaction and maintain suit- 20
`able temperatures for dehydrocyclization.
`The contaminant-sensitive catalyst used in hydrocar(cid:173)
`bon conversion comprises one or more metal compo(cid:173)
`nents on a refractory support. The metal component
`will comprise one or more from Groups IA (1), IIA (2), 25
`IVA (4), VIA (6), VIIA (7), VIII (8-10), IIIB (13) or
`IVB (14) of the Periodic Table. Applicable refractory
`supports are as described hereinabove. The contami(cid:173)
`nant-sensitive catalyst also may contain a halogen com(cid:173)
`ponent, phosphorus component, or sulfur component. 30
`The contaminant-sensitive catalyst preferably is a
`reforming catalyst, containing a non-acidic L-zeolite
`and a platinum-group metal component, which is highly
`sulfur-sensitive. It is essential that the L-zeolite be non(cid:173)
`acidic, as acidity in the zeolite lowers the selectivity to 35
`aromatics of the finished catalyst. In order to be "non(cid:173)
`acidic," the zeolite has substantially all of its cationic
`exchange sites occupied by nonhydrogen species. More
`preferably the cations occupying the exchangeable cat(cid:173)
`ion sites will comprise one or more of the alkali metals, 40
`although other cationic species may be present. An
`especially preferred nonacidic L-zeolite is potassium(cid:173)
`form L-zeolite.
`It is necessary to composite the L-zeolite with a
`binder in order to provide a convenient form for use in 45
`the catalyst of the present invention. The art teaches
`that any refractory inorganic oxide binder is suitable.
`One or more of silica, alumina or magnesia are preferred
`binder materials of the sulfur-sensitive reforming cata(cid:173)
`lyst. Amorphous silica is especially preferred, and ex- 50
`cellent results are obtained when using a synthetic
`white silica powder precipitated as ultra-fine spherical
`particles from a water solution. The silica binder prefer(cid:173)
`ably is nonacidic, contains less than 0.3 mass % sulfate
`salts, and has a BET surface area of from about 120 to 55
`160 m2/g.
`The L-zeolite and binder may be composited to form
`the desired catalyst shape by any method known in the
`art. For example, potassium-form L-zeolite and amor(cid:173)
`phous silica may be commingled as a uniform powder 60
`blend prior to introduction of a peptizing agent. An
`aqueous solution comprising sodium hydroxide is added
`to form an extrudable dough. The dough preferably will
`have a moisture content of from 30 to 50 mass % in
`order to form extrudates having acceptable integrity to 65
`withstand direct calcination. The resulting dough is
`extruded .through a suitably shaped and sized die to
`form extrudate particles, which are dried and calcined
`
`8
`by known methods. Alternatively, spherical particles
`may be formed by methods described hereinabove for
`the first reforming catalyst.
`A platinum-group metal component is another essen(cid:173)
`tial feature of the sulfur-sensitive reforming catalyst,
`with a platinum component being preferred. The plati(cid:173)
`num may exist within the catalyst as a compound such
`as the oxide, sulfide, halide, or oxyhalide, in chemical
`combination with one or more other ingredients of the
`catalytic composite, or as an elemental metal. Best re(cid:173)
`sults are obtained when substantially all of the platinum
`exists in the catalytic composite in a reduced state. The
`platinum component generally comprises from about
`0.05 to 5 mass % of the catalytic composite, preferably
`0.05 to 2 mass %, calculated on an elemental basis. It is
`within the scope of the present invention that the cata(cid:173)
`lyst may contain other metal components known to
`modify the effect of the preferred platinum component.
`Such metal modifiers may include Group IVA (14)
`metals, other Group VIII(S-10) metals, rhenium, in(cid:173)
`dium, gallium, zinc, uranium, dysprosium, thallium and
`mixtures thereof. Catalytically effective amounts of
`such metal modifiers may be incorporated into the cata(cid:173)
`lyst by any means known in the art.
`The final sulfur-sensitive reforming catalyst generally
`will be dried at a temperature of from about 100° to 320°
`C. for about 0.5 to 24 hours, followed by oxidation at a
`temperature of about 300° to 550° C. (preferably about
`350° C.) in an air atmosphere for 0.5 to 10 hours. Prefer(cid:173)
`ably the oxidized catalyst is subjected to a substantially
`water-free reduction step at a temperature of about 300°
`to 550° C. (preferably about 350° C.) for 0.5 to 10 hours
`or more. The duration of the reduction step should be
`only as long as necessary to reduce the platinum, in
`order to avoid pre-deactivation of the catalyst, and may
`be performed in-situ as part of the plant startup if a dry
`atmosphere is maintained. Further details of the prepa(cid:173)
`ration and activation of embodiments of the sulfur-sensi(cid:173)
`tive reforming catalyst are disclosed, e.g., in U.S. Pat.
`No. 4,619,906 (Lambert et al) and U.S. Pat. No.
`4,822,762 (Ellig et al.), which are incorporated into this
`specification by reference thereto.
`
`EXAMPLES
`The following examples are presented to demonstrate
`the present invention and to illustrate certain specific
`embodiments thereof. These examples should not be
`construed to limit the scope of the invention as set forth
`in the claims. There are many possible other variations,
`as those of ordinary skill in the art will recognize, which
`are within the spirit of the invention.
`The examples illustrate the feasibility and advantage
`of removing sulfur from a conversion system in the
`manner disclosed in the present invention.
`
`EXAMPLE I
`A process unit which had been utilized for the cata(cid:173)
`lytic reforming of naphtha was cleaned to remove sul(cid:173)
`fur contamination according to prior-art techniques.
`The process unit comprised three reactors and associ(cid:173)
`ated heaters, heat exchangers, charge pump, recycle
`compressor, product separator, stabilizer, piping, instru(cid:173)
`mentation and other appurtenances known to the skilled
`routineer in catalytic-reforming art.
`Heater tubes were sandjetted to remove scale. The
`entire process unit, except the product condenser which
`was bypassed, was filled with water at about 90° C.
`which was circulated for about 8 hours and then
`
`Page 5 of 7
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`ULI EXHIBIT 1003
`
`

`

`9
`drained. The unit then was filled with 5% neutralized,
`passivated, citric acid solution. The solution was circu(cid:173)
`lated for 8 hours and drained from the unit. Black
`sludge which was found to be draining from the bottom
`of each of the three reactors was washed out with wa- 5
`ter.
`The unit was pressured to about 8 atmospheres with
`nitrogen, and the gas was circulated and gradually
`heated up to 455° C. Gas was circulated for about 10
`hours, and the unit was cooled gradually to near-ambi- 10
`ent temperature.
`The unit was loaded with a reforming catalyst com(cid:173)
`prising platinum-in on alumina in order to determine the
`extent to which sulfur contamination of the equipment
`had been eliminated. The unit was pressured with hy- 15
`drogen and temperature was raised to about 370° C. at
`which time feed was introduced and temperatures were
`raised to the 450° -500° C. range as necessary to achieve
`conversion. The reactants were sampled at various
`points within the unit, including reactor inlets, and the 20
`sulfur concentration of the reactants was determined.
`
`30
`
`EXAMPLE II
`The process unit of Example I was utilized in accor(cid:173)
`dance with the invention in order to determine the 25
`efficacy of the invention. The unit was inventoried with
`