Classifications

• • 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
  • B01J29/00—Catalysts comprising molecular sieves
  • B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
  • B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
  • B01J29/60—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the type L, as exemplified by patent document US3216789
  • B01J29/61—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the type L, as exemplified by patent document US3216789 containing iron group metals, noble metals or copper
  • B01J29/62—Noble metals
• • 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
  • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
  • B01J37/0009—Use of binding agents; Moulding; Pressing; Powdering; Granulating; Addition of materials ameliorating the mechanical properties of the product catalyst
• • 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
  • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
  • B01J37/16—Reducing
  • B01J37/18—Reducing with gases containing free hydrogen
• • 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
  • C10G35/095—Catalytic reforming characterised by the catalyst used containing crystalline alumino-silicates, e.g. molecular sieves
• • 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
  • B01J2229/00—Aspects of molecular sieve catalysts not covered by B01J29/00
  • B01J2229/10—After treatment, characterised by the effect to be obtained
  • B01J2229/26—After treatment, characterised by the effect to be obtained to stabilize the total catalyst structure
• • 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
  • B01J2229/00—Aspects of molecular sieve catalysts not covered by B01J29/00
  • B01J2229/30—After treatment, characterised by the means used
  • B01J2229/36—Steaming
• • 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
  • B01J2229/00—Aspects of molecular sieve catalysts not covered by B01J29/00
  • B01J2229/30—After treatment, characterised by the means used
  • B01J2229/40—Special temperature treatment, i.e. other than just for template removal
• • 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
  • B01J2229/00—Aspects of molecular sieve catalysts not covered by B01J29/00
  • B01J2229/30—After treatment, characterised by the means used
  • B01J2229/42—Addition of matrix or binder particles

Definitions

• the invention relates to zeolite L-based reforming catalysts and their use to produce reformate having a lower content of C 9 and C10 aromatic compounds.
• Catalytic reforming is a major petroleum refining process used to raise the octane rating of naphthas (C 6 to Cu hydrocarbons) for gasoline blending. Catalytic reforming is also a principal source of aromatic chemicals, i.e., benzene, toluene and xylenes, via conversion of paraffins and naphthenes to aromatics.
• the principal reforming chemical reactions are dehydrogenation of cyclohexane to aromatics, dehydrocychzation of paraffins to aromatics, dehydroisomerization of alkylcyclopentanes to aromatics, isomerization of normal paraffins to branched paraffins, dealkylation of alkylbenzenes, and hydrocracking of paraffins to light hydrocarbons.
• the hydrocracking of paraffins to light hydrocarbons is undesirable and should be minimized because light hydrocarbons have low value.
• Catalysts commonly used in commercial reformers include a Group VIII metal, such as platinum, or platinum plus a second catalytic metal, such as rhenium or iridium, dispersed on an alumina substrate. Typically, chlorine is incorporated on the alumina to add acid functionality.
• Alumina- based reforming catalysts are suitable for aromatizing C 8 + paraffins, but are less effective for aromatizing C 6 to C 8 paraffins because these catalysts hydrocrack more of the lighter paraffins to low value fuel gas than they convert to aromatics.
• Conventional reforming catalysts are bifunctional, i.e., the catalysts enhance i) dehydrogenation and cyclization reactions on the catalytic metal sites; and ii) isomerization on separate strong acid sites in the catalyst. The undesirable hydrocracking reactions also occur on the acid sites.
• reforming catalysts have been developed which have been discovered to be particularly effective for aromatizing the C 6 to C 8 paraffin components of naphtha. These catalysts are made using zeolite, rather than alumina, as the support for the catalytic metal. They are mono-functional and contain relatively few strong acid sites. Unlike conventional bifunctional catalysts, zeolite based catalysts accomplish dehydrogenation and cyclization reactions as well as isomerization on the dispersed metallic catalytic sites. Because these zeolite-based catalysts have few strong acid sites, undesirable hydrocracking reactions are repressed. Zeolites which are preferred for reforming catalysts are large pore zeolites i.e., zeolites with a 6 to 15 Angstrom pore diameter. Zeolite L is the most preferred support for reforming catalysts, particularly wherein the catalytically active metal is platinum. Examples of such catalysts are disclosed in U.S. Patents 4,104,320 and 4,544,539.
• the “length" of a crystal is a measurement of the outer edge of the crystal perpendicular to the basal plane containing the diameter.
• the length is typically 0.1 to 0.6, preferably 0.1 to 0.3 microns and the diameter is generally 0.3 to 1.5 microns, preferably 0.4 to less than 1.0 micron.
• the crystal shape is termed "hockeypuck”.
• this ratio is less than 0.2, the shape is termed "coin”.
• These new zeolites are synthesized by hydrothermal treatment of a synthesis mixture containing water, a source of potassium, a source of Al 2 03, a source of SiO 2 and up to about 0.1 wt.%, based on the synthesis mixture, of a source of a divalent cation selected from the group consisting of magnesium, calcium, barium, manganese, chromium, cobalt, nickel and zinc.
• the divalent cation present in the synthesis mixture serves to reduce the size and regulate the shape of the resulting zeolite L crystallites and also suppresses the formation of unwanted impurities such as zeolite W.
• reformates containing a higher content of lighter aromatics e.g., benzene, toluene and xyiene (BTX) are more valuable for use in reformulated gasoline than reformates wherein the aromatics content also includes significant amounts of heavier C 9 and C 10 aromatics.
• lighter aromatics e.g., benzene, toluene and xyiene (BTX)
• Another object of the invention is to provide a process for reforming naphtha streams using this catalyst, as well as activated and regenerated versions thereof.
• Still another object of the invention is to provide a process for further activating or regenerating this catalyst.
• the invention provides a crystalline type L zeolite catalyst in which the crystals are cylindrical and have an average length of 0.6 microns or less and an average length: diameter ratio of less than about 0.5, said catalyst containing at least one catalytically active Group VIII metal of the Periodic Table and from about 0.1 to 2 wt.% of halogen.
• the invention also provides a process for reforming a C6 to C11 naphtha stream containing at least about 25 wt.% of C 6 to C 9 aliphatic and cycloaliphatic hydrocarbon comprising contacting said stream under reforming conditions with a type L zeolite catalyst in which the crystals are cylindrical and have an average length of 0.6 micron or less and an average length: diameter ratio of less than about 0.5, said catalyst containing at least one catalytically active Group VIII metal of the Periodic Table and from about 0.1 to 2 wt.% of halogen, and recovering a reformate wherein less than about 20 wt.% of the aromatics content of said reformate comprises aromatics containing nine or more carbon atoms.
• the invention further provides a process for enhancing the catalytic activity of a crystalline type L zeolite catalyst in which the crystals are cylindrical and have an average length of 0.6 microns or less and an average length: diameter ratio of less than about 0.5, said catalyst containing at least one catalytically active Group VIII metal of the Periodic Table and from about 0.1 to 2 wt.% of halogen, said processing comprising: a) contacting said catalyst with a gaseous stream comprising water, a source of chlorine, oxygen and an inert gas under oxychlorination conditions comprising a temperature of from about 450°C to 550°C and a partial pressure of chlorine derived from the source of chlorine which is greater than about 0.03 psia (206.8 Paa) for a time sufficient to form oxyhalides of said metal; b) contacting the chlorinated catalyst with a gaseous stream containing water, oxygen and an inert gas under chlorine removal conditions comprising a temperature of about 450° to 550°C
• the catalysts of this invention are selective towards the production of reformates having a high content of light C 6 to C 8 aromatics while at the same time producing less of the heavier C 9 and C 1 0 aromatics.
• Figure 1 is a graph plotting the % conversion of naphtha feed vs. reforming time for a catalyst of the invention and a conventional reforming catalyst.
• Figure 2 is a graph plotting the yield of C 6 to C 9 aromatics vs. reforming time for a catalyst of this invention and a conventional reforming catalyst.
• Zeolite L aluminosilicates which are useful as support material for the catalysts of the present invention are the small particle size cylindrically shaped crystallites such as disclosed in the above referenced U.S. patents 5,486,498 and 5,491 ,119. They are generally prepared by the hydrothermal treatment of a synthesis mixture containing water, a source of potassium, a source of AI 2 O 3 , a source of SiO 2 and up to about 0.1 wt.%, based on the weight of the synthesis mixture, of a source of divalent cation (M") selected from the group consisting of magnesium, calcium, barium, manganese, chromium, cobalt, nickel and zinc.
• M divalent cation
• M' is an alkali metal, preferably potassium or a mixture of potassium and sodium
• M" is one or a mixture of the divalent metals described above
• n is the valence of M".
• the Zeolite L of the invention is prepared by hydrothermal heating of the synthesis mixture at a temperature of about 150°C to 250°C for a period of from about 10 to 150 hours, followed by recovery, drying and optional calcining of the resulting crystalline zeolite L product.
• These zeolite L products are characterized by a cylindrical shape having relatively flat basal planes and relatively short channels within the zeolite crystalline structure.
• the length of the crystallite walls is generally in the range of from about 0.1 to 0.6 microns, more preferably from about 0.1 to 0.3 microns and the diameter is generally from about 0.3 to 1.5 microns, more preferably from about 0.4 to less than 1.0 micron.
• the average length: diameter ratio of these crystallites may generally range from about 0.05 to about 0.5, more preferably from about 0.1 to about 0.4.
• the zeolite L is made catalytically active by incorporating catalytic quantities of at least one Group VIM metal and halogen into the channel structure of the zeolite L.
• the Group VIII noble metals which are necessary for catalytic activity are those metals from Group VIII of the Periodic Table of Elements which are selected from osmium, ruthenium, rhodium, indium, palladium and platinum.
• the metals which are employed herein are platinum, rhodium or iridium, and most preferably platinum.
• the metals may be present in any combination desired. Rhenium, a Group VIIB metal, may also be present so long as at least one Group VIII noble metal is present.
• the amount of Group VIII noble metal present in the catalyst will be an effective amount and will depend, for example, on required catalyst activity, ease of uniform dispersion, and the crystal size of the type L zeolite. Crystal size limits the effective catalyst loading since highly loaded crystals of zeolite which have a large dimension parallel to the channels could be easily lead to pore plugging during operation as the noble metal agglomerates inside the channels. Generally, however, the level of metal present will range from about 0.1 to 6%, preferably 0.1 to 3.5% and more preferably 0.1 to 2.5% by weight of the catalyst.
• the amount of metal present is generally from about 0.1 to 2.0%) by weight of the catalyst if the average zeolite crystallite size parallel to the channels is greater than about 0.2 micron, and from about 1.0 to 6% by weight if the average zeolite crystallite size parallel to the channels is no greater than about 0.2 micron.
• the Group VIII noble metals may be introduced into the zeolite by, for example, ion exchange, impregnation, carbonyl decomposition, adsorption from the gaseous phase, introduction during zeolite synthesis, and adsorption of metal vapor.
• the preferably technique is ion exchange or impregnation by the so-called incipient witness method.
• Halogen may be incorporated into the catalyst by combining it with a source of halogen such as alkali or alkaline earth chlorides, fluorides, iodides or bromides.
• a source of halogen such as alkali or alkaline earth chlorides, fluorides, iodides or bromides.
• Other halogen sources include compounds such as hydrogen halide, e.g., hydrogen chloride, and ammonium halides, e.g., ammonium chloride.
• the preferred halogen source is a source of chlorine.
• the amount of halogen source combined with the catalyst should be such that the catalyst contains from about 0.1 to 2 wt.% halogen, more preferably from about 0.2 to about 1.5 wt.% halogen.
• the catalyst can be combined with the halogen source at the same time as the Group VIII metal source and using similar methods as described above.
• the zeolite L is combined with an inorganic binder material which serves as a matrix which holds the crystals together.
• Suitable binder materials include silica, alumina, silica-alumina and various clays. Molded prills or extrudates may be formed by mixing the zeolite L crystallites with water and the binder material to form a paste, shaping the paste to form molded prills or particuiate extrudates and drying the resulting product.
• the binder is added at a level such that the bound catalyst contains from about 10 to 50 wt.% binder.
• the catalyst metal and halide compound may be incorporated into the zeolite either before or after the zeolite is composited with the binder.
• the resulting zeolite L is preferably calcined after drying under conditions which tend to minimize the agglomeration of the metal component present in the catalyst. Calcination is preferably carried out in air at a temperature of 200°C to 550°C, preferably 260°C-500°C for a period of from about 1 to 12 hours.
• Freshly prepared catalyst may also be activated and halogenated by a process which includes the following essential steps:
• the described catalyst may then be used in a reforming or aromatization process. During these reactions, the catalyst gradually loses its effectiveness. The two major reasons are considered to be the production of carbonaceous deposits ("coke") and the agglomeration of the catalytic Group-VIII metal.
• the process steps outlined below provide a method for removing the coke and redispersing the metal in such a form that the catalyst is again effective.
• the process steps described below, excepting the then-extraneous coke- burn step, may also be used to distribute the Group-VIII metal throughout the zeolite before it is ever contacted with a feedstock.
• the reactor containing the catalyst may be filled with hydrocarbon feedstock, aromatic products from the dehydrocychzation reaction, and minor amounts of hydrogen and light hydrocarbons.
• the reactor is under the temperature and pressure conditions employed in the dehydrocychzation procedure. It may be appropriate to purge the catalyst bed with hydrogen or a mixture of hydrogen and light hydrocarbons to remove the feed and product hydrocarbons. After the hydrogen or hydrogen and light hydrocarbon purge, the catalyst bed may then be purged with a dry or wet, substantially inert gas, preferably nitrogen.
• the catalyst may be cooled to an appropriate initiation temperature for the coke burn cycle to follow. This cooling obviously may be accomplished by regulating the temperature of the hydrogen, recycle gas or nitrogen admitted to the catalyst bed.
• This initiation temperature preferably is less than about 900°F (482°C), more preferably less than about 850°F (454°C).
• the coke burn step is accomplished by contacting the catalyst with a gas stream containing oxygen at a temperature in the range of about 400°C to 600°C for a period of time sufficient to burn coke of the deactivated catalyst and convert the Group VIII metal to agglomerated particles.
• the preferred initial coke burn temperature is at least about 830°F (443°C) and the temperature is gradually increased up to a preferred temperature of about 925° (496°C) to 975°F (524°C).
• the catalyst preferably is held at the final coke burn temperature and final coke burn oxygen partial pressure for at least about two hours.
• the decoked catalyst is then reactivated by subjecting it to activation steps (a), (b) and (c) as described above.
• the decoked catalyst may be reduced with hydrogen prior to step (a), in which case the de-coked catalyst is contacted with a gaseous stream containing inert gas and hydrogen under reducing conditions including a temperature in the range of about 350°C to 550°C for a period of time sufficient to reduce the Group VIII metal.
• Naphtha streams which may be reformed in accordance with this invention include light to full range C6-C11 naphtha streams containing at least 25 wt.%, more preferably at least 35 wt.% and most preferably at least 50 wt.% of C 6 to C 9 aliphatic and cycloaliphatic hydrocarbons and generally less than about 25 wt.%), more preferably less than 20 wt.%, of C 9 - Cu aromatic compounds.
• Reforming is conducted by contacting the naphtha stream in a suitable reactor with activated catalyst at a preferred temperature in the range of 800°F (427°C) to 1000°F (538°C), pressure of about 50 (344.7) to 3,000 psi (20684 kPa), hourly weight space velocities in the range of 0.5 to 3.0 and in the presence of hydrogen at a molar ratio to the feed in the range of 0 to 20, more preferably 1-10 moles of hydrogen per mole of feed naphtha.
• the catalysts of the invention are highly selective towards the production of reformate having a high aromatics content, generally in excess of about 70 wt.% of C 6 to Cs aromatics (BTX). The enhanced BTX yield makes this catalyst particularly attractive for BTX production in chemical recovery processes.
• the total aromatics produced generally less than about 20 wt.%, more preferably less than 17.5 wt.% and most preferably less than 15 wt.% constitutes heavy aromatics containing nine or more carbon atoms.
• the reformate is thus more valuable for use in reformulated gasoline where lower contents of C 9 and above aromatics are desired for environmental reasons.
• a catalyst of this invention was prepared as follows: Into a circulating solution of 12.8809 g of Pt(NH 3 ) 4 CI 2 H 2 O, 19.74 g of 25.27 wt.% KOH solution, 9.09 g of KCI and 1399.0 g of water, there was added 800.0 g of a 1/16" extrudate consisting of a 70 wt.% of small particle KMgL zeolite and a 30 wt.%> alumina binder. After 1.5 hr, the loading solution was drained and the wet extrudate was dried at 300°F (149°C) for 5 hr and calcined at 662°F (350°C) for 2 hr. Elemental analysis of the resultant extrudate gave a 0.846% of Pt and 0.20% of Cl loading on the zeolite L support.
• Example 1 The catalyst of Example 1 was tested and coked in a pilot plant reactor using a C 6 -C 7 light naphtha. After about 150 hours on oil, the coked catalyst was regenerated by a regeneration procedure involving the following steps:
• a full range C 6 -Cn naphtha was hydrofined and subsequently treated with massive Ni and 4D sieve for removing sulfur to about 4 ppb sulfur in the feed.
• G. C. analysis of this treated feed gave the following composition: C 5 (0.26%), C 6 (5.85%), C 7 (18.99%), C 8 (22.35%), C 9 (21.60%), C ⁇ 0 (10.37%), Cu (2.93%), A 6 (0.32%), A 7 (3.13%), A 7 (3.13%), A 8 (5.33%), A 9 (8.07%) and A 10 (0.80%).
• the regenerated Pt/KMgL catalyst was more stable than that observed with the KX-120 catalyst in terms of converting the feed and producing A 6 -A 9 aromatics. Also, of the total aromatics produced, only about 13.6 wt.% constituted A 9 and A 10 aromatics using the catalyst of Example 2 whereas about 21.7 wt.% of the aromatics produced using the control catalyst constituted A 9 and A 10 aromatics.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
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• Crystallography & Structural Chemistry (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• General Chemical & Material Sciences (AREA)
• Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
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Citations (8)

• 1998
  • 1998-04-09 ID IDW991405A patent/ID23860A/id unknown
  • 1998-04-09 BR BR9808596-4A patent/BR9808596A/pt not_active IP Right Cessation
  • 1998-04-09 KR KR1019997009631A patent/KR20010006541A/ko not_active Application Discontinuation
  • 1998-04-09 CA CA002286696A patent/CA2286696A1/en not_active Abandoned
  • 1998-04-09 AU AU71059/98A patent/AU741522B2/en not_active Ceased
  • 1998-04-09 JP JP54610198A patent/JP2001522299A/ja active Pending
  • 1998-04-09 WO PCT/US1998/007095 patent/WO1998047615A1/en not_active Application Discontinuation
  • 1998-04-10 TW TW087105468A patent/TW362043B/zh active
  • 1998-04-17 MY MYPI98001727A patent/MY132938A/en unknown

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