WO2015000939A1 - Procédé de conversion de composés oxygénés en oléfines - Google Patents

Procédé de conversion de composés oxygénés en oléfines Download PDF

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Publication number
WO2015000939A1
WO2015000939A1 PCT/EP2014/064027 EP2014064027W WO2015000939A1 WO 2015000939 A1 WO2015000939 A1 WO 2015000939A1 EP 2014064027 W EP2014064027 W EP 2014064027W WO 2015000939 A1 WO2015000939 A1 WO 2015000939A1
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gas
olefins
catalyst
oxygenate
reactor
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PCT/EP2014/064027
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English (en)
Inventor
Richard Addison Sanborn
Ye Mon Chen
Sivakumar SADASIVAN VIJAYAKUMARI
Leslie Andrew Chewter
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Shell Internationale Research Maatschappij B.V.
Shell Oil Company
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Publication of WO2015000939A1 publication Critical patent/WO2015000939A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C1/00—Preparation of hydrocarbons from one or more compounds, none of them being a hydrocarbon
    • C07C1/20—Preparation of hydrocarbons from one or more compounds, none of them being a hydrocarbon starting from organic compounds containing only oxygen atoms as heteroatoms
    • 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
    • B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
    • B01J8/005—Separating solid material from the gas/liquid stream
    • B01J8/0055—Separating solid material from the gas/liquid stream using cyclones
    • 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
    • B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
    • B01J8/02—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds
    • 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
    • B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
    • B01J8/18—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles
    • B01J8/1845—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles with particles moving upwards while fluidised
    • 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
    • B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
    • B01J8/18—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles
    • B01J8/1845—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles with particles moving upwards while fluidised
    • B01J8/1863—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles with particles moving upwards while fluidised followed by a downward movement outside the reactor and subsequently re-entering it
    • 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
    • B01J2208/00—Processes carried out in the presence of solid particles; Reactors therefor
    • B01J2208/00008—Controlling the process
    • B01J2208/00017—Controlling the temperature
    • B01J2208/00327—Controlling the temperature by direct heat exchange
    • B01J2208/00336—Controlling the temperature by direct heat exchange adding a temperature modifying medium to the reactants
    • B01J2208/00353—Non-cryogenic fluids
    • B01J2208/00362—Liquid
    • 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
    • B01J2208/00—Processes carried out in the presence of solid particles; Reactors therefor
    • B01J2208/00743—Feeding or discharging of solids
    • B01J2208/00752—Feeding
    • 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
    • B01J2208/00—Processes carried out in the presence of solid particles; Reactors therefor
    • B01J2208/00743—Feeding or discharging of solids
    • B01J2208/00761—Discharging
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P30/00—Technologies relating to oil refining and petrochemical industry
    • Y02P30/20—Technologies relating to oil refining and petrochemical industry using bio-feedstock
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P30/00—Technologies relating to oil refining and petrochemical industry
    • Y02P30/40—Ethylene production

Definitions

  • the invention relates to a method for the conversion of oxygenates to olefins.
  • the invention further relates to the use of a purge gas to prevent side reactions in the area above the gas/solid separation device inlet.
  • Oxygenate-to -olefin (“OTO") processes are well described in the art. Typically, oxygenate-to -olefin processes are used to produce predominantly ethylene and propylene. An example of such an oxygenate-to-olefm process is described in US Patent Application Publication No. 2011/112344, which is herein incorporated by reference.
  • the publication describes a process for the preparation of an olefin product comprising ethylene and/or propylene, comprising a step of converting an oxygenate feedstock in an oxygenate-to -olefins conversion system, comprising a reaction zone in which an oxygenate feedstock is contacted with an oxygenate conversion catalyst under oxygenate conversion conditions, to obtain a conversion effluent comprising ethylene and/or propylene.
  • Additional compounds especially higher molecular weight hydrocarbons are typically produced with the ethylene and propylene in an oxygenate-to -olefins process.
  • a method of improving the yield of lower molecular weight olefins is desired as these olefins, mainly ethylene and propylene, serve as feeds for the production of numerous chemicals.
  • the catalyst and the activity of the catalyst are important to the performance of the reaction step.
  • US 7,622,625 teaches the use of an inert gas into a second zone of the reactor to increase circulation of materials in the second zone of the reactor to reduce the amount of coke deposited on catalyst or on the surfaces within these zones.
  • the inert gas is fed via line 12 to port 13 where it is passed into the reactor.
  • a single purge gas inlet is not an efficient way of introducing the purge gas and this leads to non-specific purging of the reactor vessel and either high consumption of purge gas and/or inefficient purging of regions of the reactor where long gas residence times lead to the highest rates of coke formation and deposition.
  • the invention provides a method of converting an oxygenate comprising feedstock to olefins comprising: feeding an oxygenate comprising feedstock into a reactor containing an oxygenate to olefins conversion catalyst; contacting the feedstock with the catalyst at oxygenate conversion conditions to produce an effluent comprising olefins and catalyst; removing the effluent from the reactor through a gas/solid separation device inlet; separating the catalyst from the effluent in a gas/solid separation device comprising an inlet, an outlet for catalyst and an outlet pipe for gas; and adding an inert gas in a distributed fashion to a region in the reactor vessel above the gas/solid separation device inlet(s).
  • the method for converting oxygenates to olefins and specifically the use of a purge gas fed to the reactor above the gas/solid separation device inlet described herein provides an improved method for the conversion of oxygenates to olefins.
  • the use of this feature is effective in any known oxygenate to olefin process, including processes known as methanol to olefins (MTO) and methanol to propylene (MTP).
  • MTO methanol to olefins
  • MTP methanol to propylene
  • the oxygenate to olefins process can, in certain embodiments, be as described in any of the following references: US
  • the oxygenate to olefins process receives as a feedstock a stream comprising one or more oxygenates.
  • An oxygenate is an organic compound that contains at least one oxygen atom.
  • the oxygenate is preferably one or more alcohols, preferably aliphatic alcohols where the aliphatic moiety has from 1 to 20 carbon atoms, preferably from 1 to 10 carbon atoms, more preferably from 1 to 5 carbon atoms and most preferably from 1 to 4 carbon atoms.
  • the alcohols that can be used as a feed to this process include lower straight and branched chain aliphatic alcohols.
  • ethers and other oxygen containing organic molecules can be used. Suitable examples of oxygenates include methanol, ethanol, n-propanol, isopropanol, methyl ethyl ether, dimethyl ether, diethyl ether, di-isopropyl ether,
  • the feedstock comprises one or more of methanol, ethanol, dimethyl ether, diethyl ether or a combination thereof, more preferably methanol or dimethyl ether and most preferably methanol.
  • the oxygenate is obtained as a reaction product of synthesis gas.
  • Synthesis gas can, for example, be generated from fossil fuels, such as from natural gas or oil, or from the gasification of coal.
  • the oxygenate is obtained from biomaterials, such as through fermentation.
  • the oxygenate feedstock can be obtained from a pre-reactor, which converts methanol at least partially into dimethylether and water. Water may be removed, by e.g., distillation. In this way, less water is present in the process of converting oxygenates to olefins, which has advantages for the process design and lowers the severity of hydrothermal conditions to which the catalyst is exposed.
  • the oxygenate to olefins process may, in certain embodiments, also receive an olefin co-feed.
  • This co-feed may comprise olefins having carbon numbers of from 1 to 8, preferably from 3 to 6 and more preferably 4 or 5.
  • suitable olefin co-feeds include butene, pentene and hexene.
  • the oxygenate feed comprises one or more oxygenates and olefins, more preferably oxygenates and olefins in an oxygenate:olefm molar ratio in the range of from 1000: 1 to 1 : 1, preferably 100: 1 to 1 :1. More preferably, in a oxygenate:olefm molar ratio in the range of from 20: 1 to 1 : 1, more preferably in the range of l8: l to 1 :1, still more preferably in the range of l5: l to 1 : 1, even still more preferably in the range of 14 : 1 to 1 : 1.
  • the olefin co-feed may also comprise paraffins. These paraffins may serve as diluents or in some cases they may participate in one or more of the reactions taking place in the presence of the catalyst.
  • the paraffins may include alkanes having carbon numbers from 1 to 10, preferably from 3 to 6 and more preferably 4 or 5.
  • the paraffins may be recycled from separation steps occurring downstream of the oxygenate to olefins conversion step.
  • the oxygenate to olefins process may, in certain embodiments, also receive a diluent co-feed to reduce the concentration of the oxygenates in the feed and suppress side reactions that lead primarily to high molecular weight products.
  • the diluent should generally be non- reactive to the oxygenate feedstock or to the catalyst. Possible diluents include helium, argon, nitrogen, carbon monoxide, carbon dioxide, methane, water and mixtures thereof. The more preferred diluents are water and nitrogen with the most preferred being water.
  • the diluent may be used in either liquid or vapor form.
  • the diluent may be added to the feedstock before or at the time of entering the reactor or added separately to the reactor or added with the catalyst.
  • the diluent is added in an amount in the range of from 1 to 90 mole percent, more preferably from 1 to 80 mole percent, more preferably from 5 to 50 mole percent, most preferably from 5 to 40 mole percent.
  • steam is produced as a by-product, which serves as an in-situ produced diluent.
  • additional steam is added as diluent.
  • the amount of additional diluent that needs to be added depends on the in-situ water make, which in turn depends on the composition of the oxygenate feed. Where the diluent provided to the reactor is water or steam, the molar ratio of oxygenate to diluent is between 10: 1 and 1 :20.
  • the oxygenate feed is contacted with the catalyst at a temperature in the range of from 200 to 1000 °C, preferably of from 300 to 800 °C, more preferably of from 350 to 700 °C, even more preferably of from 450 to 650°C.
  • the feed may be contacted with the catalyst at a temperature in the range of from 530 to 620 °C, or preferably of from 580 to 610 °C.
  • the feed may be contacted with the catalyst at a pressure in the range of from 0.1 kPa (1 mbar) to 5 MPa (50 bar), preferably of from 100 kPa (1 bar) to 1.5 MPa (15 bar), more preferably of from 100 kPa (1 bar) to 300 kPa (3 bar).
  • Reference herein to pressures is to absolute pressures.
  • WHSV is defined as the mass of the feed (excluding diluents) per hour per mass of catalyst.
  • the WHSV should preferably be in the range of from 1 hr -1 to 5000 hr 1 .
  • the process takes place in a reactor and the catalyst may be present in the form of a fixed bed, a moving bed, a fluidized bed, a dense fluidized bed, a fast or turbulent fluidized bed, or a circulating fluidized bed.
  • riser reactors, hybrid reactors or other reactor types known to those skilled in the art may be used.
  • more than one of these reactor types may be used in series.
  • the reactor is a riser reactor. The advantage of a riser reactor is that it allows for very accurate control of the contact time of the feed with the catalyst, as riser reactors exhibit a flow of catalyst and reactants through the reactor that approaches plug flow.
  • Catalysts suitable for use in the conversion of oxygenates to olefins may be made from practically any small or medium pore molecular sieve.
  • a suitable type of molecular sieve is a zeolite.
  • Suitable zeolites include, but are not limited to AEI, AEL, AFT, AFO, APC, ATN, ATT, ATV, AWW, BIK, CAS, CHA, CHI, DAC, DDR, EDI, ERI, EUO, FER, GOO, HEU, KFI, LEV, LOV, LTA, MFI, MEL, MON, MTT, MTW, PAU, PHI, RHO, ROG, THO, TON and substituted forms of these types.
  • Suitable catalysts include those containing a zeolite of the ZSM group, in particular of the MFI type, such as ZSM-5, the MTT type, such as ZSM-23, the TON type, such as ZSM-22, the MEL type, such as ZSM-11, and the FER type.
  • Other suitable zeolites are for example zeolites of the STF-type, such as SSZ-35, the SFF type, such as SSZ-44 and the EU-2 type, such as ZSM-48.
  • Preferred zeolites for this process include ZSM-5, ZSM-22 and ZSM-23.
  • a preferred MFI-type zeolite for the oxygenate to olefins conversion catalyst has a silica-to-alumina ratio, SAR, of at least 60, preferably at least 80. More preferred MFI-type zeolite has a silica-to-alumina ratio, SAR, in the range of 60 to 150, preferably in the range of 80 to 100.
  • the zeolite-comprising catalyst may comprise more than one zeolite.
  • the catalyst comprises at least a more-dimensional zeolite, in particular of the MFI type, more in particular ZSM-5, or of the MEL type, such as zeolite ZSM-11, and a one- dimensional zeolite having 10-membered ring channels, such as of the MTT and/or TON type.
  • zeolites in the hydrogen form are used in the zeolite-comprising catalyst, e.g., HZSM-5, HZSM-11, and HZSM-22, HZSM-23.
  • the zeolite-comprising catalyst e.g., HZSM-5, HZSM-11, and HZSM-22, HZSM-23.
  • at least 50wt%, more preferably at least 90wt%, still more preferably at least 95wt% and most preferably 100wt% of the total amount of zeolite used is in the hydrogen form. It is well known in the art how to produce such zeolites in the hydrogen form.
  • SAPOs siliocoaluminophosphates
  • SAPOs have a three dimensional microporous crystal framework of P02+, A102-, and Si02 tetrahedral units.
  • Suitable SAPOs include SAPO-17, -18, 34, -35, -44, but also SAPO-5, -8, -11, -20, -31, -36, 37, -40, -41, -42, -47 and -56; aluminophosphates (A1PO) and metal substituted (silico)aluminophosphates (MeAlPO), wherein the Me in MeAlPO refers to a substituted metal atom, including metal selected from one of Group IA, IIA, IB, IIIB, IVB, VB, VIB, VIIB, VIIIB and lanthanides of the Periodic Table of Elements.
  • Preferred SAPOs for this process include SAPO-34, SAPO-17 and SAPO-18.
  • Preferred substituent metals for the MeAlPO include Co, Cr, Cu, Fe, Ga, Ge, Mg, Mn, Ni, Sn, Ti, Zn and Zr.
  • the molecular sieves described above are formulated into molecular sieve catalyst compositions for use in the oxygenates to olefins conversion reaction.
  • the molecular sieves are formulated into catalysts by combining the molecular sieve with a binder and/or matrix material and/or filler and forming the composition into particles by techniques such as spray- drying, pelletizing, or extrusion.
  • the molecular sieve may be further processed before being combined with the binder and/or matrix. For example, the molecular sieve may be milled and/or calcined.
  • Suitable binders for use in these molecular sieve catalyst compositions include various types of aluminas, aluminophosphates, silicas and/or other inorganic oxide sol.
  • the binder acts like glue binding the molecular sieves and other materials together, particularly after thermal treatment.
  • Various compounds may be added to stabilize the binder to allow processing.
  • Matrix materials are usually effective at among other benefits, increasing the density of the catalyst composition and increasing catalyst strength (crush strength and/or attrition resistance).
  • Suitable matrix materials include one or more of the following: rare earth metals, metal oxides including titania, zirconia, magnesia, thoria, beryllia, quartz, silica or sols, and mixtures thereof, for example, silica-magnesia, silica-zirconia, silica-titania, and silica- alumina.
  • matrix materials are natural clays, for example, kaolin.
  • a preferred matrix material is kaolin.
  • the molecular sieve, binder and matrix material are combined in the presence of a liquid to form a molecular sieve catalyst slurry.
  • the amount of binder is in the range of from 2 to 40 wt%, preferably in the range of from 10 to 35 wt%, more preferably in the range of from 15 to 30 wt%, based on the total weight of the molecular sieve, binder and matrix material, excluding liquid (after calcination).
  • the slurry may be mixed, preferably with rigorous mixing to form a substantially homogeneous mixture.
  • suitable liquids include one or more of water, alcohols, ketones, aldehydes and/or esters. Water is the preferred liquid.
  • the mixture is colloid-milled for a period of time sufficient to produce the desired texture, particle size or particle size distribution.
  • the molecular sieve, matrix and optional binder can be in the same or different liquids and are combined in any order together, simultaneously, sequentially or a combination thereof.
  • water is the only liquid used.
  • the slurry is mixed or milled to achieve a uniform slurry of sub-particles that is then fed to a forming unit.
  • the forming unit is a spray dryer.
  • the forming unit is typically operated at a temperature high enough to remove most of the liquid from the slurry and from the resulting molecular sieve catalyst composition.
  • the particles are then exposed to ion-exchange using an ammonium nitrate or other appropriate solution.
  • the ion exchange is carried out before the phosphorous impregnation.
  • the ammonium nitrate is used to ion exchange the zeolite to remove alkali ions.
  • the zeolite can be impregnated with phosphorous using phosphoric acid.
  • the ion exchange is carried out after the phosphorous impregnation.
  • alkali phosphates may be used to impregnate the zeolite with phosphorous, and then the ammonium nitrate and heat treatment are used to ion exchange and convert the zeolite to the H+ form.
  • the catalyst may be formed into spheres, tablets, rings, extrudates or any other shape known to one of ordinary skill in the art.
  • the catalyst may be extruded into various shapes, including cylinders and trilobes.
  • the average particle size is in the range of from 1-200 ⁇ , preferably from 50-100 ⁇ . If extrudates are formed, then the average size is in the range of from 1 mm to 10 mm, preferably from 2 mm to 7 mm.
  • the catalyst may further comprise phosphorus as such or in a compound, i.e.
  • a MEL or MFI-type zeolite comprising catalyst additionally comprises phosphorus.
  • the molecular sieve catalyst is prepared by first forming a molecular sieve catalyst precursor as described above, optionally impregnating the catalyst with a phosphorous containing compound and then calcining the catalyst precursor to form the catalyst.
  • the phosphorous impregnation may be carried out by any method known to one of skill in the art.
  • the phosphorus-containing compound preferably comprises a phosphorus species such as P0 4 3 ⁇ , P-(OCH 3 ) 3 , or P2O5, especially P0 4 3 ⁇ .
  • the phosphorus-containing compound comprises a compound selected from the group consisting of ammonium phosphate, ammonium dihydrogen phosphate, dimethylphosphate, metaphosphoric acid and trimethyl phosphite and phosphoric acid, especially phosphoric acid.
  • the phosphorus containing compound is preferably not a Group II metal phosphate.
  • Group II metal species include magnesium, calcium, strontium and barium; especially calcium.
  • phosphorus can be deposited on the catalyst by impregnation using acidic solutions containing phosphoric acid (H 3 P0 4 ). The concentration of the solution can be adjusted to impregnate the desired amount of phosphorus on the precursor. The catalyst precursor may then be dried.
  • the catalyst precursor containing phosphorous (either in the framework or impregnated) is calcined to form the catalyst.
  • the calcination of the catalyst is important to determining the performance of the catalyst in the oxygenate to olefins process.
  • the calcination may be carried out in any type of calciner known to one of ordinary skill in the art.
  • the calcination may be carried out in a tray calciner, a rotary calciner, or a batch oven, optionally in the presence of an inert gas and/or oxygen and/or steam.
  • the calcination may be carried out at a temperature in the range of from 400 °C to 1000 °C, preferably in a range of from 450 °C to 800 °C, more preferably in a range of from 500 °C to 700 ° C.
  • Calcination time is typically dependent on the degree of hardening of the molecular sieve catalyst composition and the temperature and ranges from about 15 minutes to about 2 hours.
  • the calcination is carried out in air at a temperature of from 500 °C to 600 °C.
  • the calcination is carried out for a period of time from 30 minutes to 15 hours, preferably from 1 hour to 10 hours, more preferably from 1 hour to 5 hours.
  • the calcination is carried out on a bed of catalyst.
  • a bed of catalyst For example, if the calcination is carried out in a tray calciner, then the catalyst precursor added to the tray forms a bed which is typically kept stationary during the calcination. If the calcination is carried out in a rotary calciner, then the catalyst added to the rotary drum forms a bed that although not stationary does maintain some form and shape as it passes through the calciner.
  • the feedstocks described above are converted primarily into olefins.
  • the olefins produced from the feedstock typically have from 2 to 30 carbon atoms, preferably from 2 to 8 carbon atoms, more preferably from 2 to 6 carbon atoms, most preferably ethylene and/or propylene.
  • diolefms having from 4 to 18 carbon atoms, conjugated or nonconjugated dienes, polyenes, vinyl monomers and cyclic olefins may be produced in the reaction.
  • the feedstock preferably one or more oxygenates
  • the oxygenate is methanol
  • the olefins are ethylene and/or propylene.
  • the products from the reactor are typically separated and/or purified to prepare separate product streams in a recovery system.
  • Such systems typically comprise one or more separation, fractionation or distillation towers, columns, and splitters and other associated equipment, for example, various condensers, heat exchangers, refrigeration systems or chill trains, compressors, knock-out drums or pots, pumps and the like.
  • the recovery system may include a demethanizer, a deethanizer, a depropanizer, a wash tower often referred to as a caustic wash tower and/or quench tower, absorbers, adsorbers, membranes, an ethylene-ethane splitter, a propylene-propane splitter, a butene- butane splitter and the like.
  • the preferred products, ethylene and propylene are preferably separated and purified for use in derivative processes such as polymerization processes.
  • the products may comprise C4+ olefins, paraffins and aromatics that may be further reacted, recycled or otherwise further treated to increase the yield of the desired products and/or other valuable products.
  • C4+ olefins may be recycled to the oxygenate to olefins conversion reaction or fed to a separate reactor for cracking.
  • the paraffins may also be cracked in a separate reactor, and/or removed from the system to be used elsewhere or possibly as fuel.
  • the product will typically comprise some aromatic compounds such as benzene, toluene and xylenes. Although it is not the primary aim of the process, xylenes can be seen as a valuable product.
  • Xylenes may be formed in the OTO process by the alkylation of benzene and, in particular, toluene with oxygenates such as methanol.
  • a separate fraction comprising aromatics, in particular benzene, toluene and xylenes is separated from the gaseous product and at least in part recycled to the oxygenate to olefins conversion reactor as part of the oxygenate feed.
  • part or all of the xylenes in the fraction comprising aromatics are withdrawn from the process as a product prior to recycling the fraction comprising aromatics to the oxygenate to olefins conversion reactor.
  • the C4+ olefins and paraffins formed in the oxygenate to olefins conversion reactor may be further reacted in an additional reactor containing the same or a different molecular sieve catalyst.
  • the C4+ feed is converted over the molecular sieve catalyst at a temperature in the range of from 500 to 700 °C.
  • the additional reactor is also referred to as an OCP reactor and the process that takes place in this reactor is referred to as an olefin cracking process.
  • a product which includes at least ethylene and/or propylene and preferably both.
  • the gaseous product may comprise higher olefins, i.e. C4+ olefins, and paraffins.
  • the gaseous product is retrieved from the second reactor as part of a second reactor effluent stream.
  • the olefin feed is contacted with the catalyst at a temperature in the range of from 500 to 700 °C, preferably of from 550 to 650°C, more preferably of from 550 to 620°C, even more preferably of from 580 to 610°C; and a pressure in the range of from 0.1 kPa (1 mbara) to 5 MPa (50 bara), preferably of from 100 kPa (1 bara) to 1.5 MPa (15 bara), more preferably of from 100 kPa ( 1 bara) to 300 kPa (3 bara).
  • Reference herein to pressures is to absolute pressures.
  • the C4+ olefins are separated into at least two fractions: a C4 olefin fraction and a C5+ olefin fraction.
  • the C4 olefins are recycled to the oxygenate to olefins conversion reactor and the C5+ olefins are fed to the OCP reactor.
  • the cracking behavior of C4 olefins and C5 olefins is believed to be different when contacted with a molecular sieve catalyst, in particular above 500 °C.
  • the cracking of C4 olefins is an indirect process which involves a primary
  • oligomerization process to a C8, C12 or higher olefin followed by cracking of the oligomers to lower molecular weight hydrocarbons including ethylene and propylene, but also, amongst other things, to C5 to C7 olefins, and by-products such as C2 to C6 paraffins, cyclic hydrocarbons and aromatics.
  • the cracking of C4 olefins is prone to coke formation, which places a restriction on the obtainable conversion of the C4 olefins.
  • paraffins, cyclics and aromatics are not formed by cracking. They are formed by hydrogen transfer reactions and cyclization reactions. This is more likely in larger molecules.
  • the C4 olefin cracking process which as mentioned above includes intermediate oligomerization, is more prone to by-product formation than direct cracking of C5 olefins.
  • the conversion of the C4 olefins is typically a function of the temperature and space time (often expressed as the weight hourly space velocity). With increasing temperature and decreasing weight hourly space velocity (WHSV) conversion of the C4 olefins in the feed to the OCP increases. Initially, the ethylene and propylene yields increase, but, at higher conversions, yield decreases at the cost of a higher by-product make and, in particular, a higher coke make, limiting significantly the maximum yield obtainable.
  • WHSV weight hourly space velocity
  • C5 olefin cracking is ideally a relatively straight forward- process whereby the C5 olefin cracks into a C2 and a C3 olefin, in particular above 500°C.
  • This cracking reaction can be run at high conversions, up to 100%, while maintaining, at least compared to C4 olefins, high ethylene and propylene yields with a significantly lower byproduct and coke make.
  • C5+ olefins can also oligomerize, this process competes with the more beneficial cracking to ethylene and propylene.
  • the C4 olefins are recycled to the oxygenate to olefins conversion reactor.
  • the C4 olefins are alkylated with, for instance, methanol to C5 and/or C6 olefins.
  • These C5 and/or C6 olefins may subsequently be converted into at least ethylene and/or propylene.
  • the main by-products from this oxygenate to olefins conversion reaction are again C4 and C5 olefins, which can be recycled to the oxygenate to olefins conversion reactor and olefin cracking reactor, respectively.
  • the gaseous products further include C4 olefins
  • at least part of the C4 olefins are provided to (i) the oxygenate to olefins conversion reactor together with or as part of the oxygenate feed, and/or (ii) the olefin cracking reactor as part of the olefin feed, more preferably at least part of the C4 olefins is provided to the oxygenate to olefins conversion reactor together with or as part of the oxygenate feed.
  • the gaseous products further include C5 olefins
  • at least part of the C5 olefins are provided to the olefin cracking reactor as part of the olefin feed.
  • the olefin feed to the olefin cracking reactor comprises C4+ olefins, preferably C5+ olefins, more preferably C5 olefins.
  • the oxygenate to olefins conversion reactor and the optional OCP reactor are operated as riser reactors where the catalyst and feedstock are fed at the base of the riser and an effluent stream with entrained catalyst exits the top of the riser.
  • gas/solid separators are necessary to separate the entrained catalyst from the reactor effluent.
  • the gas/solid separator may be any separator suitable for separating gases from solids.
  • the gas/solid separator comprises one or more centrifugal separation units, preferably cyclone units, optionally combined with a stripper section.
  • the reactor effluent is preferably cooled in the gas/solid separator to terminate the conversion process and prevent the formation of by-products outside the reactors.
  • the cooling may be achieved by use of a water quench.
  • the catalyst may be returned to the reaction zone from which it came, to another reaction zone or to a regeneration zone.
  • the catalyst that has been separated in the gas/solid separator may be combined with catalyst from other gas/solid separators before it is sent to a reaction zone or to the regeneration zone.
  • the inlets to the gas/solid separators are located towards the top of the reactor vessels. Between the inlet to the gas/solid separators and the top of the reactor vessel is a region in which there is little gas flow. Since this is a region that is most distant from the feed distribution device at the bottom of the reactor and not in the direct flow path of the gas to the gas/solid separator, it is typically where zones of stagnant gas may occur. This leads to coke formation and deposition as a result of the extended residence time and subsequent reaction of olefins in this gas.
  • This invention provides for feeding an inert gas in the region above the inlet(s) to the gas/solid separator(s) to prevent any stagnant zones and the associated deposition of coke.
  • the purge gas rate should be a rate suitable to decrease the gas residence times in the region above the gas/solid separation inlet(s) to less than 5 seconds, preferably less than 3 seconds and more preferably less than 2 seconds.
  • the gas residence times in this region are preferably in the range of from 0.01 seconds to 5 seconds, preferably from 0.1 seconds to 3 seconds and more preferably from 0.5 seconds to 2 seconds.
  • the inert gas used for this purpose can be the same as or different than the diluent used in the reactor and can be selected from the same list of possible gases.
  • the inert gas is passed into the reactor using a purge gas distribution system comprising a plurality of feed points distributed through the region between the gas/solid separator inlet(s) and the top of the reactor vessel for feeding the inert gas into the reactor.
  • the feed points can be optimized to decrease the gas residence time in this region on the basis of fluid flow calculations, estimates and/or measurements. This improves the effectiveness of the purge gas system in preventing stagnant zones while still providing the same volume of gas.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Combustion & Propulsion (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

La présente invention concerne un procédé de conversion en oléfines d'une charge d'alimentation comprenant des composés oxygénés, ledit procédé consistant à : introduire une charge d'alimentation comprenant des composés oxygénés dans un réacteur contenant un catalyseur de conversion de composés oxygénés en oléfines ; mettre en contact la charge d'alimentation avec le catalyseur dans des conditions de conversion de composés oxygénés pour produire un effluent comprenant des oléfines et le catalyseur ; retirer l'effluent du réacteur par une entrée de dispositif de séparation gaz/solide ; séparer le catalyseur de l'effluent dans un dispositif de séparation gaz/solide comprenant une entrée, une sortie pour le catalyseur et un tuyau de sortie pour le gaz ; et ajouter un gaz inerte dans le réacteur en un point au-dessus de l'entrée du dispositif de séparation gaz/solide.
PCT/EP2014/064027 2013-07-02 2014-07-02 Procédé de conversion de composés oxygénés en oléfines WO2015000939A1 (fr)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006049815A1 (fr) * 2004-11-01 2006-05-11 Uop Llc Purge des flux gazeux diriges vers des zones stagnantes dans un reacteur de conversion de composes oxygenes en olefines
US20060149108A1 (en) * 2004-12-30 2006-07-06 Miller Lawrence W Oxygenate conversion reactor catalyst coolers
US20080207973A1 (en) * 2004-11-01 2008-08-28 Paolo Palmas Purge Gas Streams to Stagnant Zones within Oxygenate-to-Olefin Reactor

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006049815A1 (fr) * 2004-11-01 2006-05-11 Uop Llc Purge des flux gazeux diriges vers des zones stagnantes dans un reacteur de conversion de composes oxygenes en olefines
US20080207973A1 (en) * 2004-11-01 2008-08-28 Paolo Palmas Purge Gas Streams to Stagnant Zones within Oxygenate-to-Olefin Reactor
US20060149108A1 (en) * 2004-12-30 2006-07-06 Miller Lawrence W Oxygenate conversion reactor catalyst coolers

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