Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C2/00—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms
  • C07C2/86—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms by condensation between a hydrocarbon and a non-hydrocarbon
  • C07C2/862—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms by condensation between a hydrocarbon and a non-hydrocarbon the non-hydrocarbon contains only oxygen as hetero-atoms
  • C07C2/865—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms by condensation between a hydrocarbon and a non-hydrocarbon the non-hydrocarbon contains only oxygen as hetero-atoms the non-hydrocarbon is an ether
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C15/00—Cyclic hydrocarbons containing only six-membered aromatic rings as cyclic parts
  • C07C15/02—Monocyclic hydrocarbons
  • C07C15/067—C8H10 hydrocarbons
  • C07C15/08—Xylenes
• • 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
  • B01J29/40—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C2/00—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms
  • C07C2/54—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms by addition of unsaturated hydrocarbons to saturated hydrocarbons or to hydrocarbons containing a six-membered aromatic ring with no unsaturation outside the aromatic ring
  • C07C2/64—Addition to a carbon atom of a six-membered aromatic ring
  • C07C2/66—Catalytic processes
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C2/00—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms
  • C07C2/86—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms by condensation between a hydrocarbon and a non-hydrocarbon
  • C07C2/861—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms by condensation between a hydrocarbon and a non-hydrocarbon the non-hydrocarbon contains only halogen as hetero-atoms
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C2/00—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms
  • C07C2/86—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms by condensation between a hydrocarbon and a non-hydrocarbon
  • C07C2/862—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms by condensation between a hydrocarbon and a non-hydrocarbon the non-hydrocarbon contains only oxygen as hetero-atoms
  • C07C2/864—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms by condensation between a hydrocarbon and a non-hydrocarbon the non-hydrocarbon contains only oxygen as hetero-atoms the non-hydrocarbon is an alcohol
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C2/00—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms
  • C07C2/86—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms by condensation between a hydrocarbon and a non-hydrocarbon
  • C07C2/868—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms by condensation between a hydrocarbon and a non-hydrocarbon the non-hydrocarbon contains sulfur as hetero-atom
• • 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
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C2529/00—Catalysts comprising molecular sieves
  • C07C2529/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites, pillared clays
  • C07C2529/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
  • C07C2529/40—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11
• • 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
  • Y02P20/00—Technologies relating to chemical industry
  • Y02P20/50—Improvements relating to the production of bulk chemicals
  • Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts

Definitions

• This invention relates to a process for the selective production of para-xylene by catalytic methylation of toluene in the presence of a solid catalyst.
• U.S. Patent No. 2,904,607 to Mattox refers to alkylation of aromatic hydrocarbons with an olefin in the presence of a crystalline metallic aluminosilicate having
• U.S. Patent No. 3,751,504 to Keown et al. and U.S. Patent No. 3,751,506 to Burress describe vapor phase alkylation of aromatic hydrocarbons with olefins, e.g. benzene with ethylene, in the presence of a ZSM-5 type zeolite catalyst.
• xylene isomers e.g. ortho-, meta- and para- xylene
• the latter is of particular value being useful in the manufacture of terephthalic acid which is an intermediate in the manufacture of synthetic fibers such 5 as Dacron brand fiber available from the DuPont de
• U.S. Patent 4,001,346 to Chu relates to a process for the selective production of para-xylene by ethylation of toluene in the presence of a catalyst comprising a crystalline aluminosilicate zeolite which has undergone prior treatment to deposit a coating of between about 15 and about 75 weight percent of coke thereon.
• U.S. Patent 4,097,543 to Haag et al. relates to a process for the selective production of para-xylene (up to about 77%) by disproportionation of toluene in the presence of a crystalline aluminosilicate catalyst which has undergone precoking to deposit a coating of at least about 2 weight percent coke thereon.
• U.S. Patent 4,554,394 to Forbus and Kaeding teach the use of phosphorus-treated zeolite catalysts for enhancing para-selectivity in aromatics conversion processes.
• U.S. Patent 4,623,633 to Young relates to the use of thermal shock calcination of aluminosilicates to produce up to 66% para-xylene selectivity.
• the invention provides a process for the selective production of para-xylene which comprises reacting toluene with a methylating agent in the presence of a catalyst comprising a microporous material having a Constraint Index, measured prior to selectivation, of from about 1 to about 12, which catalyst has been selectivated by the steps of: (a) presteaming the catalyst at a temperature of from about 800*C to about 1050'C for at least about 10 minutes;
• the present invention improves selectivity and yield in a process for producing para-xylene from toluene by steaming and precoking the catalyst under controlled conditions, and then continuously controlling the degree of coke loading during process operation.
• the order of the steaming and precoking steps is critical in the present invention, as is the severity of both steps. These two steps in sequence enable the process of the present invention to provide unusually high selectivity for para-xylene at commercially useful toluene conversions of 5 weight percent or more per pass, typically 7 weight percent or more per pass.
• Para-xylene selectivities typically exceed 90 weight percent in the present process, and preferably exceed 94 weight percent.
• Conversion conditions typically include temperature between about 300* and about 750*C, preferably between about 500* and about 700"C, pressure of between about 1 atmosphere and 1000 psig, weight hourly space velocity of between about 0.5 and 1000, and a molar ratio of methylating agent to toluene (in the reactor charge) of less than about 5, more typically from about 0.05 to about 5.
• Suitable catalyst presteaming temperatures range from about 800*C to about 1050*C, preferably from about 900* to about 1040*C, while the presteaming contact time ranges from about 10 minutes to several hundred hours, more typically up to about 100 hours. Higher steaming temperatures may irreversibly degrade the catalyst, causing its catalytic activity for toluene methylation to decrease below a commercially useful level.
• the catalyst may be selectivated by treatment with one or more elements such as Si, P, Mg, or B.
• Phosphorus-treated zeolites are taught in U.S. Patent 4,554,394 to Forbus and Kaeding, cited above, which is incorporated by reference as if set forth at length herein for the method of depositing such elements on the catalyst.
• coke loading is used herein in terms of weight percent to refer to the amount of coke deposited on the catalyst as a percentage of the total weight of the composite catalyst. For example, a 100 gram catalyst sample having coke loading of 5 weight percent would contain 5 grams of coke and 95 grams of composite catalyst.
• the process of the present invention is preferably carried out in a fluid bed or moving bed reactor so that the extent of coke loading can be controlled by varying the severity and/or the frequency of continuous oxidative regeneration in the catalyst regenerator. Coke deposited on the catalyst during normal processing is partially removed by regeneration. The amount of coke left on the catalyst after regeneration may be controlled to balance the desired para-xylene selectivity against catalyst activity. Generally, more severe and/or more frequent regenerations remove more coke from the catalyst and less severe and/or less frequent regenerations remove less coke from the 5. catalyst.
• the catalyst decoking step of the present invention is continuously controlled to enable the operator to maintain the desired para-xylene selectivity, or to adjust the para-xylene selectivity and toluene conversion 0 as required.
• precoking of the catalyst will be accomplished by initially utilizing the uncoked catalyst in the toluene methylation reaction, during which coke is deposited on the catalyst surface and thereafter controlled within the above-noted range of from about 1 to about 20 weight percent (preferably from about 1 to about 15 weight percent, more preferably from about 1 to about 10 weight percent, and most preferably from about 1 to about 5 weight percent) by periodic regeneration by exposure to an oxygen-containing atmosphere at an elevated temperature.
• the preselectivated catalyst described herein is its ease of regenerability.
• the preselectivated catalyst can easily be regenerated by burning off a controlled amount of coke in the partial combustion atmosphere of the regenerator at temperatures in the range of from about 400* to about 700'C.
• the coke loading on the catalyst is thereby reduced in the regenerator, but not eliminated, so that the regenerated catalyst returning to the toluene methylation reaction zone is coke-loaded at a level of from about 1 to about 20 weight percent, more typically in the range of from about 1 to about 5 weight percent.
• the members of the class of microporous materials useful as catalysts in the present invention have an effective pore size of generally from about 5 to about 8 Angstroms or larger, such as to freely sorb normal hexane.
• the structure must provide constrained access to larger molecules. It is sometimes possible to judge from a known crystal structure whether such constrained access exists. For example, if the only pore windows in a crystal are formed by 8-membered rings of silicon and aluminum atoms, then access by molecules of larger cross-section than normal hexane is excluded and the microporous crystalline material is not of the desired type. Windows of 10-membered rings are preferred, although, in some instances, excessive puckering of the rings or pore blockage may render these microporous materials ineffective.
• the catalyst contains a zeolite having a Constraint Index, measured prior to selectivation, of between about 1 and about 12.
• zeolite catalysts include ZSM-5, ZSM-11, ZSM-12, ZSM-22, ZSM-23, ZSM-35, ZSM-48, and MCM-22, with ZSM-5 and ZSM-11 being particularly preferred.
• Zeolite ZSM-5 and the conventional preparation thereof are described in U.S. Patent Number 3,702,886, the disclosure of which is incorporated herein by reference.
• Other preparations for ZSM-5 are described in U.S. Patent Numbers Re. 29,948 (highly siliceous ZSM-5) ; 4,100,262 and 4,139,600, the disclosure of these is incorporated herein by reference.
• Zeolite ZSM-11 and the conventional preparation thereof are described in U.S. Patent Number 3,709,979, the disclosure of which is incorporated herein by reference.
• Zeolite ZSM-12 and the conventional preparation thereof are described in U.S. Patent Number 3,832,449, the disclosure of which is incorporated herein by reference.
• Zeolite ZSM-23 and the conventional preparation thereof are described in U.S. Patent Number 4,076,842, the disclosure of which is incorporated herein by reference.
• Zeolite ZSM-35 and the conventional preparation thereof are described in U.S. Patent Number 4,016,245, the disclosure of which is incorporated herein by reference.
• Another preparation of ZSM-35 is described in U.S. Patent Number 4,107,195, the disclosure of which is incorporated herein by reference.
• ZSM-48 and the conventional preparation thereof is taught by U.S. Patent 4,375,573, the disclosure of which is incorporated herein by reference.
• MCM-22 is disclosed in U.S. Patents 5,304,698 to Husain, 5,250,277 to Kresge et al., 5,095,167 to
• Additional molecular sieves which find utility in conjunction with the present invention include pillared silicates and/or clays; aluminophosphates, e.g. ALPO-5, VPI-5; silicoaluminophosphates, e.g. SAPO-5, SAPO-37, SAPO-31, SAPO-40, SAPO-41; and other metal aluminophosphates.
• aluminophosphates e.g. ALPO-5, VPI-5
• silicoaluminophosphates e.g. SAPO-5, SAPO-37, SAPO-31, SAPO-40, SAPO-41
• other metal aluminophosphates e.g. SAPO-5, SAPO-37, SAPO-31, SAPO-40, SAPO-41
• Other metal aluminophosphates e.g. SAPO-5, SAPO-37, SAPO-31, SAPO-40, SAPO-41
• other metal aluminophosphates
• a fluidizable catalyst containing ZSM-5 was calcined at 538*C (1000'F) for 3 hours to remove residual volatile material and then steamed at 1025*C (1877*F) for 4 hours at 101 kPa (0 psig) steam. Toluene and methanol in a molar ratio of 4/1 was passed over 40 grams of catalyst in a fluidized bed of catalyst operated below the transport velocity at reaction conditions of 597*C
• the reactor was operated in a batch mode with respect to catalyst for a period of 11 hours.
• a two-phase liquid product consisting of a hydrocarbon phase and an aqueous phase was sampled at different times during the run and analyzed.
• the hydrocarbon phase contained the desired xylene product rich in para-xylenes.
• the catalyst was purged with nitrogen and the reactor cooled and a sample of catalyst removed and analyzed for coke content.
• composition of the hydrocarbon phase shows a para-selectivity (para/para+meta+ortho) _ of 93.9% for a catalyst containing 4.97 wt.% coke and not exposed to cyclic hydrocarbon process/regeneration cycles.
• Example 2 The composition of the hydrocarbon phase (Table 1) shows a para-selectivity (para/para+meta+ortho) _ of 93.9% for a catalyst containing 4.97 wt.% coke and not exposed to cyclic hydrocarbon process/regeneration cycles.
• a sample of the steamed fluidizable catalyst described in Example 1 was loaded into a fluid bed reactor.
• a mixture of toluene and methanol in a toluene/methanol molar ratio of 4/1 was passed over the catalyst at reaction conditions of 599*C (1110*F), 1.0 WHSV, and 101 kPa (0 psig) .
• the reactor was operated under cyclic hydrocarbon process/regeneration conditions with respect to catalyst.
• a cycle consisted of processing toluene/methanol feed for 6 or 12 hours, followed by a nitrogen purge for 30 minutes during which time the catalyst bed was cooled to 552*C (1025*F), followed by an air regeneration for 2 hours at 552*C (1025°F) , followed by a nitrogen purge for 30 minutes during which time the catalyst bed was reheated to 599*C (1110*F) for the next hydrocarbon cycle.
• a two-phase liquid product consisting of a hydrocarbon phase and an aqueous phase was sampled at the end of the hydrocarbon cycle and analyzed.
• the hydrocarbon phase contained the desired xylene product rich in para-xylenes.

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• 1995
  • 1995-11-09 CA CA002202858A patent/CA2202858A1/en not_active Abandoned
  • 1995-11-09 JP JP8516224A patent/JPH10508854A/ja active Pending
  • 1995-11-09 KR KR1019970703115A patent/KR970707061A/ko not_active Ceased
  • 1995-11-09 AU AU41075/96A patent/AU4107596A/en not_active Abandoned
  • 1995-11-09 WO PCT/US1995/014667 patent/WO1996015083A1/en not_active Application Discontinuation
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