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WO2009058133A1 - Procédé de régénération avec une utilisation efficace d'oxygène - Google Patents

Procédé de régénération avec une utilisation efficace d'oxygène Download PDF

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Publication number
WO2009058133A1
WO2009058133A1 PCT/US2007/083013 US2007083013W WO2009058133A1 WO 2009058133 A1 WO2009058133 A1 WO 2009058133A1 US 2007083013 W US2007083013 W US 2007083013W WO 2009058133 A1 WO2009058133 A1 WO 2009058133A1
Authority
WO
WIPO (PCT)
Prior art keywords
catalyst
temperature
coke
oxygen
bed
Prior art date
Application number
PCT/US2007/083013
Other languages
English (en)
Inventor
Leon Yuan
James L. Bixby
Kyle P. Austin
Brian D. Nabozny
Original Assignee
Uop Llc
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Uop Llc filed Critical Uop Llc
Priority to PCT/US2007/083013 priority Critical patent/WO2009058133A1/fr
Publication of WO2009058133A1 publication Critical patent/WO2009058133A1/fr

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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
    • B01J38/00—Regeneration or reactivation of catalysts, in general
    • B01J38/04—Gas or vapour treating; Treating by using liquids vaporisable upon contacting spent catalyst
    • B01J38/12—Treating with free oxygen-containing gas
    • 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
    • B01J23/90—Regeneration or reactivation
    • B01J23/96—Regeneration or reactivation of catalysts comprising metals, oxides or hydroxides of the noble metals
    • 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
    • C10G11/00—Catalytic cracking, in the absence of hydrogen, of hydrocarbon oils
    • C10G11/14—Catalytic cracking, in the absence of hydrogen, of hydrocarbon oils with preheated moving solid catalysts
    • C10G11/18—Catalytic cracking, in the absence of hydrogen, of hydrocarbon oils with preheated moving solid catalysts according to the "fluidised-bed" technique
    • C10G11/182—Regeneration

Definitions

  • Catalytic processes for the conversion of hydrocarbons are well known and extensively used. Invariably the catalysts used in these processes become deactivated for one or more reasons. Where the accumulation of coke deposits causes the deactivation, reconditioning of the catalyst to remove coke deposits restores the activity of the catalyst.
  • Coke is normally removed from catalyst by contact of the coke-containing catalyst at high temperature with an oxygen-containing gas to combust and to remove the coke in a regeneration process. These processes can be carried out in-situ within a fixed-bed or the catalyst may be removed from a vessel in which the hydrocarbon conversion takes place and transported to a separate regeneration zone for coke removal. Arrangements for continuously or semi-continuously removing catalyst particles from a reaction zone and for coke removal in a regeneration zone are well known.
  • Some beds have low flow areas where oxygen in the effluent can increase, while the low flow area continues to consume all of the available oxygen, thus making controlled peak burning difficult over the entire bed by merely controlling inlet and outlet oxygen concentrations.
  • catalyst deactivation Exposure of high surface area catalyst to high temperatures for prolonged periods of time will create a more amorphous material having a reduced surface area which in turn lowers the activity of the catalyst until it reaches a level where it is considered deactivated. Deactivation of this type is permanent, thereby rendering the catalyst unusable. When moisture is present— water is a by-product of the coke combustion— the deactivating effects of high temperature exposure are compounded.
  • US 3,753,926 discloses a method for regenerating a hydrocarbon conversion catalyst comprising rhenium using two carbon burning steps, where the first step is at a relatively low temperature with a small amount of oxygen and the second step is at a relatively higher temperature and a relatively higher amount of oxygen.
  • US 4,507,397 discloses a sulfur removal step in a semi-continuous regeneration process prior to carbonaceous deposit oxidation.
  • US 5,001,095 discloses a method for improving a coke combustion process by segregating flue gas from the process into a high moisture content portion that is removed and a low moisture content portion that is recycled to the process.
  • US 5,151,392 discloses a moving bed regeneration process with separate dispersion and chloriding steps following a coke combustion zone, which allows improved platinum re -dispersion by controlling chloride equilibrium with either oxygen-enriched or oxygen-depleted environments.
  • US 5,854,162 discloses an offsite regeneration process using a moving bed furnace for a combustion step similar for used hydro-treatment catalysts, and adds a oxy- halogenation step in a sealed rotating furnace that avoids the onset of gas channeling, which improves the homogeneity of catalyst halogenation.
  • US 5,965,473 discloses a method for reducing chloride emissions from a cyclic regeneration operation while saving operating costs.
  • US 6,103,652 discloses a staged combustion process and apparatus for regenerating a catalyst in a moving bed that includes at least two separate successive combustion zones.
  • a ramp rate is iteratively determined by allowing the first cycle to occur without ramping, then using the empirical information to set a time based on when the previous cycle coke burn completes.
  • FIG. 4 shows inlet and outlet temperatures for a bed during combustion where temperature is ramped at 89 minutes.
  • the present invention is applicable to a number of hydrocarbon conversion processes which utilize a catalyst. For example, it is useful in the isomerization of normal butane to isobutane and the isomerization of mixed Cg aromatics, including those of high ethylbenzene content, to meta-xylene or para-xylene.
  • the present invention may also be used in upgrading light straight run naphtha, which is a mixture rich in C5 and C5 paraffins (pentanes and hexanes), to the corresponding branched isomers, which have higher octane numbers than the feed naphtha.
  • Another hydrocarbon conversion process in which the present invention may be used is dehydrogenation of light paraffins (C2 to C5, but primarily C3 and C4) to the corresponding olefins.
  • Catalytic reforming is a well-established hydrocarbon conversion process employed in the petroleum refining industry for improving the octane quality of hydrocarbon feedstocks, the primary product of reforming being motor gasoline.
  • the art of catalytic reforming is well known and does not require extensive description herein.
  • a feedstock is admixed with a recycle stream comprising hydrogen and contacted with catalyst in a reaction zone.
  • the usual feedstock for catalytic reforming is a petroleum fraction known as naphtha and having an initial boiling point of 82°C (180 0 F) and an end boiling point of 204 0 C (400 0 F).
  • the catalytic reforming process is particularly applicable to the treatment of straight run gasolines comprised of relatively large concentrations of naphthenic and substantially straight chain paraffinic hydrocarbons, which are subject to aromatization through dehydrogenation and/or cyclization reactions.
  • Reforming may be defined as the total effect produced by dehydrogenation of cyclohexanes and dehydroisomerization of alkylcyclopentanes to yield aromatics, 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. Further information on reforming processes may be found in, for example, US 4,119,526; US 4,409,095; and US 4,440,626.
  • a catalytic reforming reaction is normally effected in the presence of catalyst particles comprised of one or more Group VIII noble metals (e.g., platinum, iridium, rhodium, palladium) and a halogen combined with a porous carrier, such as a refractory inorganic oxide.
  • Alumina is a commonly used carrier.
  • the halogen is normally chlorine.
  • the particles are usually spheroidal but may be cylindrical, and have a diameter of from 1.5 mm to 3.1 mm (1/16-inch to 1/8-inch), though they may be as large as 6.55 mm (1/4-inch). In a particular regenerator, however, it is desirable to use catalyst particles which fall in a relatively narrow size range.
  • catalyst particles become deactivated as a result of mechanisms such as the deposition of coke on the particles; that is, after a period of time in use, the ability of catalyst particles to promote reforming reactions decreases to the point that the catalyst is no longer useful.
  • the catalyst must be reconditioned, or regenerated, before it can be reused in a reforming process.
  • the present invention is applicable to a moving bed regeneration zone and a fixed bed regeneration zone.
  • Fresh catalyst particles are placed in a reaction zone, which may be comprised of several subzones.
  • Catalyst may be withdrawn from the bottom of the reaction zone and transported to a regeneration zone where a hereinafter described multi-step or multi- section regeneration process is used to recondition the catalyst to restore its full reaction promoting ability.
  • Catalyst flows by gravity through the regeneration zone, and then is withdrawn and furnished to the reaction zone.
  • Catalyst may flow through successive steps or sections, or successive steps may be applied to a non- flowing section of catalyst.
  • a fixed bed or batch reaction zone may be switched into a regenerator zone by applying successive steps to a non-moving catalyst bed.
  • catalyst is contacted with a hot oxygen- containing gas stream (known in reforming processes as recycle gas) in order to remove coke which accumulates on surfaces of the catalyst while it is in a hydrocarbon conversion reaction zone.
  • Coke is comprised primarily of carbon but is also comprised of a relatively small quantity of hydrogen.
  • the mechanism of coke removal is oxidation mainly to carbon dioxide and water.
  • Coke content of spent catalyst may be as much as 20% of the catalyst weight, but 5 to 7% is a more typical amount.
  • coke is usually oxidized at temperatures ranging from 371° to 550 0 C (700° to 1020 0 F), but temperatures in localized regions may reach as low as 200 0 C (392°F) and as high as 600 0 C (1112°F) or more. It is preferred to not greatly exceed 600 0 C (1112°F).
  • Oxygen for the combustion of coke enters the combustion step of the regeneration zone in what has been termed a recycle gas.
  • the recycle gas contains a low concentration of oxygen usually on the order of 0.2 to 3.0 % by volume.
  • the arrangement of a typical combustion section for a continuous regeneration zone may be seen in US 3,652,231.
  • the arrangement for a batch regenerator zone may be seen by description in US 5,965,473 which describes an off-stream catalyst bed of a reforming process with cyclic catalyst regeneration.
  • Such a batch regenerator zone contains catalyst particles in an elongated bed having two elongated sides. In one common arrangement, the two elongated sides are open for transverse gas flow through the catalyst bed. In another common arrangement, the elongated bed has two ends, which are generally perpendicular to the elongated sides and which are open for axial gas flow through the bed. If the arrangement is a cylinder, then it will only have one elongated side.
  • the oxygen- containing gas is combined with the flue gas to replace the oxygen consumed by the coke combustion and the combined gas is recycled to the combustion step or section.
  • the oxygen-containing gas was typically air.
  • the amount of air needed to replenish the oxygen consumed during the coke combustion is relatively small, 3% of the volumetric rate of the recycle gas stream depending upon actual inlet oxygen concentration and actual oxygen utilization efficiency.
  • breakthrough occurs at a location spaced half the distance down the total length of the bed in the combustion section. It is known to those skilled in the art that catalyst particles of the type used in the hydrocarbon conversion processes of this invention have a large surface area, which results from the existence of a multiplicity of pores. When the catalyst particles reach the breakthrough point in the bed, the coke left on the surface of the particles is deep within the pores and therefore the oxidation reaction occurs at a much slower rate.
  • a batch regenerator when the catalyst bed is contacted with recycle gas the coke begins to burn.
  • the flow rate, temperature, and oxygen concentration of the recycle gas are controlled in order to produce a combustion front within the catalyst bed and to prevent the temperature of the combustion front from exceeding 566°C (1050 0 F).
  • Combusting coke in this manner is well known in the art of hydrocarbon processing.
  • the combustion front passes slowly from the inlet to outlet of the catalyst bed.
  • the intensity of coke burning and the rate of progression of the combustion front can be controlled by monitoring the temperature at various locations within the bed or the bulk temperature of the flue gas stream leaving the bed.
  • the regeneration zone will usually include additional treatment steps or sections for the catalyst. One such step is a halogenation step.
  • the halogenation step provides the means of incorporating and maintaining the desired level of halogen in the final catalytic composite.
  • the halogen adjustment step employs a halogen, or halogen- containing compound in air or an oxygen atmosphere.
  • the preferred halogen for incorporation into the catalytic composite is chlorine.
  • the preferred halogen or halogen- containing compound utilized during the halogenation step is chlorine, HCl or a precursor of these compounds.
  • An oxygen atmosphere is generally employed and desired in carrying out the halogenation step. The presence of oxygen aids in the dispersion of the metallic catalyst components on the carrier.
  • a lower water concentration in the environment of the combustion section can facilitate the halogenation step as catalyst with a lower water content drop downward into the halogenation section of the regeneration zone.
  • the concentration of chlorine in the halogenation section is governed by the Deacon equilibrium equation.
  • the lag time can be estimated from the heat up step for regenerator preceding the burn step. It takes some time until the changes of inlet vapor temperature impacts the temperature at the outlet.
  • a typical heat up curve is shown in FIG. 1 to heat up a regenerator from 149 to 407 0 C using an inert gas stream containing at most only insubstantial amounts of oxygen. Here an insubstantial amount of oxygen is an amount less than 0.2 vol-%.
  • FIG. 1 shows a calculation of heat-up temperature waves traveling axially through a bed of catalyst at one minute intervals. This graphically illustrates the lag time required for a change in temperature at the inlet of the bed, to reach the outlet of the bed.
  • FIGS. 2 thru 5 illustrate the importance of proper starting time for temperature ramping while also showing the inlet temperature and the increased outlet temperature associated with coke combustion. Without any temperature ramping step the temperature at the outlet starts to fall in the calculated bed after 91 minutes into the burn step the oxygen efficiency is calculated to be as low as 70% based on the extra time required to assure complete combustion at a constant inlet temperature such as 407 0 C.
  • the oxygen efficiency is calculated as high as 96% based on the increased kinetics of burning coke at a higher temperature such as 482°C.
  • a temperature excursion will occur due to undesirable peak burning as shown in FIG. 2, where a substantially linear ramp up occurs at 83 minutes over a period of 18 minutes and the normal peak burn temperature at the end of the combustion is greatly exceeded.
  • FIG. 3 shows the axially traveling heat waves at 9 minute intervals.
  • FIG. 4 shows a change in start time for temperature ramping from 83 minutes in FIG. 2 to 89 minutes in FIG. 4 and the normal peak burn temperature by the end of combustion is not exceeded in FIG. 4.
  • FIG. 5 shows the axially traveling heat waves at 9 minute intervals.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Materials Engineering (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • General Chemical & Material Sciences (AREA)
  • Catalysts (AREA)

Abstract

Cette invention concerne la régénération d'un catalyseur à coke par combustion de telle sorte que le catalyseur peut être réutilisé dans une réaction de conversion d'hydrocarbure. L'achèvement de la combustion du coke est généralement mesuré par une combinaison de température ou de changement de la concentration en oxygène. La chute des températures de sortie demande du temps pour attendre que les augmentations de température d'entrée descendent de façon correspondante dans le régénérateur. Des temps de réponse plus rapides pourraient être attendus de l'augmentation de la concentration en oxygène, mais une faible augmentation de concentration peut conduire à une augmentation significative de la température de combustion de pic ce qui a une incidence négative sur la durée de vie du catalyseur. Une combustion de pic régulée est difficile sur la totalité du lit si on ne régule les concentrations en oxygène qu'à l'entrée et qu'à la sortie. Par conséquent, l'invention combine un temps mort mesuré pour le déplacement de la température avec une étape de mise en rampe de la température d'entrée pour assurer une combustion complète du coke avec un rendement en oxygène élevé, fournissant ainsi une régénération rapide qui permet davantage de temps de fonctionnement aux conditions réactionnelles voulues.
PCT/US2007/083013 2007-10-30 2007-10-30 Procédé de régénération avec une utilisation efficace d'oxygène WO2009058133A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/US2007/083013 WO2009058133A1 (fr) 2007-10-30 2007-10-30 Procédé de régénération avec une utilisation efficace d'oxygène

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PCT/US2007/083013 WO2009058133A1 (fr) 2007-10-30 2007-10-30 Procédé de régénération avec une utilisation efficace d'oxygène

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Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070217961A1 (en) * 2003-12-31 2007-09-20 Leon Yuan Regeneration Method with Efficient Oxygen Utilization

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070217961A1 (en) * 2003-12-31 2007-09-20 Leon Yuan Regeneration Method with Efficient Oxygen Utilization

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