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
  • C07C2/864—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
  • C07C2/54—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
• • 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
  • C07C15/00—Cyclic hydrocarbons containing only six-membered aromatic rings as cyclic parts
  • C07C15/02—Monocyclic hydrocarbons
  • C07C15/067—C8H10 hydrocarbons
  • C07C15/08—Xylenes
• • 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

• the invention relates generally to a process for the aikylation of aromatic compounds, e.g., toluene methylation, with a zeolite catalyst, e.g., an aluminosilicate zeolite which has been modified to be a shape selective catalyst, in the presence of hydrogen and steam, said process relating to introduction of the alkylating agent and hydrogen in a certain order of introduction and within a certain temperature range.
• a zeolite catalyst e.g., an aluminosilicate zeolite which has been modified to be a shape selective catalyst
• Toluene methylation (TM) is a catalytic reaction of toluene with methanol to produce xylenes as shown below:
• Toluene methylation is an equimolar reaction, i.e., one mole of toluene reacts with one mole of methanol.
• Methanol may react with itself to form olefins.
• Toluene can be over-alkyialed to form aromatics.
• the toluene:methanol mole ratio may be greater than 1 : 1 or in the range from 2: 1 to 20: 1.
• Zeolites which are crystalline solids made up of aluminum-substituted SiO 4 tetrahedral units joined together to form different ring and cage structures into a crystalline framework can be used as catalyst for toluene methylation.
• the physical structure of zeolite is very porous with a large internal and external surface area.
• Zeolites can be shape-selective catalysts due to steric and electronic effects. Shape selective properties can be obtained by modifying the zeolite, e.g., narrowing zeolite pore opening size, inactivation of the external surface of the zeolite or altering zeolite acidity. Deposition of certain compounds or elements on the zeolite can make it more shape selective, e.g., compounds containing iron, zinc, phosphorus, rare earth metal oxides, etc.
• PX Para-xylene
• concentration of p-xylene in the xylene isomers are of commercial importance.
• Para-xylene (PX) is of particular value as a large volume chemical intermediate in a number of applications being useful in the manufacture of terephthalates which are intermediates for the manufacture of PET. It would be advantageous for a process to produce p-xylene at concentrations of at least 85% or at least 90%.
• U.S. Patent no. 4, 152,364 discloses a process for the selective production of para-xylene by methvlation of toluene in the presence of a catalyst of zeolite which has been modified or treated with a phosphorus compound.
• Methylation of toluene is by contacting toluene with methanol at a temperature between about 250oC and about 750°C, preferably between about 400°C and about 700 ° C.
• the toluene and methanol are introduced into the reactor separately or at different temperatures.
• U.S. Patent no. 4,250,345 discloses a process for the selective production of para-xylene by methylation of toluene in the presence of a catalyst of zeolite which has been modified or treated with a phosphorus compound.
• Methylation of toluene is by contacting toluene with methanol at a temperature between about 250oC and about 750°C, preferably between about 500oC and about 700X.
• the toluene and methanol are introduced into the reactor separately or at different temperatures.
• U.S. Patent no. 7,084,318 discloses a method of preparing a xylene product with a phosphorus-treated ZSM-5 catalyst having a startup procedure of introducing toluene, methanol and hydrogen at a liquid hourly space velocity (LHSV) of more than 5 hr "! at a temperature of 200°C or above, operating at these conditions for a half hour to twenty hours and then reducing the LHSV and increasing the temperature to 500oC - 700°C.
• LHSV liquid hourly space velocity
• a process which would increase p-xylene concentration in the mixed-xylene product stream and which would decrease catalyst deactivation and maintain toluene conversion to increase time on stream would be advantageous.
• the present invention is for a method of alkylation of an aromatic comprising:
• Contacting the aromatic compound; the alkylating agent; hydrogen, an inert gas or a mixture thereof; and water with a shape-selective zeolite catalyst in a reactor may comprise the steps of:
• Figure 1 shows a graph of hours on stream v. per cent toiuene conversion for Examples 1-7 with hydrogen, steam, toiuene and methanol each being introduced into the reactor at a reactor temperature of 200°C or of 480T.
• Toluene methylation is known to occur over zeolite or zeolite-type catalysts, in particular, ZSM-5-type zeolite catalysts.
• zeolite or zeolite-type catalysts in particular, ZSM-5-type zeolite catalysts.
• a thermodynamic equilibrium mixture of ortho (o)-, meta (m)- and para (p)-xyienes is formed from the methylation of toluene.
• Thermodynamic equilibrium compositions of o-, m-, and p-xylenes may be around 25, 50 and 25 mole%, respectively, at a reaction temperature of about 500 °C.
• Such toluene methylation may occur over at wide range of temperatures, however.
• a high purity grade (99+%) p-xylene is desirable for its oxidation to terephthalic acid process.
• an increased concentration of p-xylene over equilibrium is desirable.
• Zeolite is a crystalline hydrated alurninosilicate that may also contain other metals, such as sodium, calcium, barium, and potassium, and that has ion exchange properties (Encarta® World English Dictionary [North American Edition] ⁇ & (P) 2001 Microsoft Corporation).
• Examples of zeolites are ZSM-5, ZSM- 1 1, ZSM-5/ZSM-1 1 intermediate, ZSM-12, ZSM-21 , ZSM-22, ZSM- 23, ZSM-35, ZSM-38, ZSM-48, ZSM-50, MCM-22, Zeolite L, Zeolite Beta and Mordenite which are known in the art.
• the present invention incorporates modification of zeolites to be shape selective catalysts.
• ZSM-5 zeolite is a porous material containing intersecting two-dimensional pore structure with 10-membered oxygen rings. Zeolites with such 10-membered oxygen ring pore structures are often classified as medium-pore zeolites. As used herein, the expression "ZSM-5- type" is meant to refer to those zeolites that are isostructurally the same as ZSM-5 zeolites.
• ZSM-5" and ZSM-5-type may also be used herein interchangeably to encompass one another and should not be construed in a limiting sense.
• the ZSM-5 zeolite catalyst may include those having a silica/alumina molar ratio of 200 or higher, more
• the starting ZSM-5 may be an NH 4 + or H + form and may contain traces of other cations. Modification of ZSM-5-type zeolite with phosphorus-containing compounds has been shown to provide shape selective properties to the catalyst, yielding significantly greater amounts of p-xylene than the thermodynamic equilibrium value when used in toluene methylation compared to unmodified catalysts.
• the catalysts of the present invention are shape selective zeolite catalysts.
• a shape selective zeolite catalyst is a zeolite modified by treating with phosphorus- containing compounds including, but are not limited to, phosphonic, phosphinous, phosphorus and phosphoric acids, salts and esters of such acids and phosphorous halides.
• phosphorus- containing compounds including, but are not limited to, phosphonic, phosphinous, phosphorus and phosphoric acids, salts and esters of such acids and phosphorous halides.
• phosphoric acid I3PO 4
• ammonium hydrogen phosphate (NH 4 ) 2 HPO 4 ) may be used as the phosphorus-containing compound to provide a catalyst for toluene methylation with shape
• Such modified catalysts may contain phosphorus (P) in an. amount of from about 0.01 to about 0.15 g P/g zeolite, more particularly from about 0.02 to about 0.1 3 g P/g zeolite, and more particularly from about 0.07 g P/g zeolite to about 0.12 g P/g zeolite, and still more particularly from about 0.09 g P/g zeolite to about 0.1 1 g P/g zeolite.
• the phosphorus -treated zeolite may be dried.
• the zeolite is a ZSM-5-type.
• the P-modified ZSM-5 catalyst may be contacted with an appropriate feed of an aromatic hydrocarbon and an alkylating agent under alkylation reaction conditions to carry out aromatic alkylation.
• an aromatic hydrocarbon and an alkylating agent under alkylation reaction conditions to carry out aromatic alkylation.
• One particular application of the catalyst is for use in toluene methylation utilizing a toluene/methanol feed.
• the process of the present invention may also have a gas feed.
• the feed gas may include hydrogen or an inert gas.
• inert gases are nitrogen, carbon monoxide, carbon dioxide and the noble gases (helium, neon, argon, krypton, xenon and radon).
• the feed gas may be hydrogen, an inert gas or mixtures thereof.
• alkylation feed is meant to encompass the aromatic compound and the alkylating agent.
• methylation feed is meant to encompass the feed of toluene and methanol.
• water that may be in the form of steam may also be introduced into the reactor.
• the water or steam used for the alkylation reaction may be introduced with or without hydrogen or inert gas as cofeed with the alkylation feed to the reactor during the start up of the alkylation reaction, or it may be introduced subsequent to initial start
• liquid water may be added and vaporized prior to its mixing with cofeed gas (if any) and the alkylation feed.
• cofeed gas if any
• the use of water cofeed is described in U.S. Patent No. 7,060,864 issued June 13, 2006, and entitled “Toluene Methylation Process," and in U.S. Patent No. 7,186.872 issued March 6, 2007, as a continuation-in-part application entitled "Toluene
• the reactor pressure for toluene methylation or other aromatic alkylation may vary, but typically ranges from about 10 to about 1000 psig.
• Reactor temperatures may vary, but typically ) range from about 400 to about 700°C.
• the catalyst bed temperature may be adjusted to a selected reaction temperature to effect a desired conversion.
• the temperature may be increased gradually at a rate of from about l °C/min to about 10°C/min to provide the desired final reactor temperature.
• reactor temperature refers to the temperature as measured at the inlet of the catalyst bed of the reactor.
• reaction may be carried out in a variety of different reactors that are commonly used for carrying out aromatic alkylation reactions.
• Single or multiple reactors in series and/or parallel are suitable for carrying out the aromatic alkylation.
• Alkylating agent, hydrogen, water and/or aromatic may be added to the product stream entering the second and subsequent reactors when using multiple reactors in series.
• the aromatic alkylation process of the present invention involves introducing hydrogen, an inert gas or a mixture thereof into a reactor or reaction zone at a temperature less than reaction
• hydrogen is introduced into a reactor or reaction zone which has been heated to a temperature less than reaction temperature.
• hydrogen is introduced into a reactor or reaction zone while heating to a temperature less than reaction temperature.
• the temperature less than reaction temperature may be a temperature of about 200oC to less than about 400oC.
• the temperature may be in the range from about 200°C to about 250oC .
• One specific example of the temperature is about 200oC .
• water either as liquid water or as steam., and/or an aromatic, such as toluene, may also be introduced into the reactor or reaction zone at a temperature less than reaction temperature.
• Hydrogen and water may be mixed with each other or either or both may be mixed with the aromatic before introduction into the reactor or reaction zone or hydrogen, water and aromatic may be introduced separately into the reactor or reaction zone.
• No significant amount of alkylating agent is introduced into the reactor or reaction zone when the temperature is less than reaction temperature. With the context of this invention, "no significant amount of alkylating agent” is meant to mean more than 1 % by weight.
• the aromatic alkylaiion process of the present invention also involves introducing an alkylating agent into the reactor or reaction zone at a temperature within the range of reaction temperature.
• the alkylating agent is introduced into a reactor or reaction zone which has been heated to a temperature of more than about 400°C to about 700° .
• the temperature may be in the range from about 400oC to about 500oC .
• One specific example of the temperature is about 480oC
• water, either as liquid water or as steam, and/or an aromatic, such as toluene may also be introduced into the reactor or reaction zone at a
• the aromatic and the alkylating agent may be mixed with each other or either or both may be mixed with the water before introduction into the reactor or reaction, zone or the alkylating agent, water and aromatic may be introduced separately into the reactor or reaction zone.
• an inert gas or a mixture thereof is introduced into a reactor or reaction zone at a temperature less than reaction temperature, e.g., about 200°C to less than about 400oC , after which an alkylating agent is introduced into the reactor or reaction zone at a temperature within the range of reaction temperature, e.g., more than about 400oC to about 700 ° .
• the water, either as liquid water or as steam, and the aromatic introduced into the reactor or reaction zone can be at a temperature less than reaction temperature or at a temperature within the range of reaction temperature and can be introduced into the reactor before, as or after the hydrogen, inert gas or a mixture thereof is introduced, before, as or after the alkylating agent is introduced or between introduction of the hydrogen, inert gas or a mixture thereof and the alkylating agent.
• the alkylating agent, water, either as liquid water or as steam, and the aromatic are introduced into the reactor or reaction zone at a temperature within the range of reaction temperature, e.g., more than about 400oC to about 700oC .
• hydrogen and water are introduced into the reactor or reaction zone at a temperature less than reaction temperature, e.g., about 200 " C to less than about 400 ° C and. the alkylating agent and the aromatic are introduced into the reactor or reaction zone at a temperature within the range of reaction temperature, e.g., more than about 400oC to
• hydrogen, the aromatic and water are introduced into the reactor or reaction zone at a temperature less than reaction temperature, e.g., about 200°C to less than about 400°C.
• catalytic activity can be expressed as the % moles of the toluene converted with respect to the moles of toluene fed and can be defined by the following formulas:
• selectivity for mixed xylenes may be expressed as:
• Mole% Mixed Xylene Selectivity [X tx /(Tj-T 0 )] x 100 (2) where, X tx is the number of moles of mixed (o-, m- or p-) xylenes in the product.
• selectivity for p-xylene may be expressed as:
• Mole% p-Xylene Selectivity (X p /X tx ) x 100 (3) where X p is the number of moles of p-xylene.
• para-xylene yield may be expressed as:
• methanol conversion may be expressed as:
• Mole % Methanol Conversion [(Mj - M 0 )/Mj] x 100 (5) where, Mi is the number of moles of methanol fed and M 0 is the number of moles methanol unreacted.
• methanol selectivity for toluene methylation may be expressed as:
• Mole% Methanol Selectivity fX tx /(M;-M 0 )] x 100 (6) where, X tx is the number of moles of mixed (o-, m- or p-) xylenes, M, is the number of moles of methanol fed and M 0 is the number of moles of unreacted methanol.
• a NhL f -ZSM-5 zeolite powder having a S1O2/AI2O3 mole ratio of about 275 was treated with aqueous H3PO4 and was then calcined at a temperature of about 530 °C.
• the phosphorus treated ZSM-5 zeolite was crushed into fine powder and was then combined with alumina as binder and extruded into 1 /16-inch diameter cylindrical-shaped extrudates.
• the bound zeolite eximdates were then calcined or heated to a temperature of 530 °C to form Catalyst A that contained about 20 wt% alumina binder and approximately 7,4 wt% phosphorus by total weight of catalyst.
• Catalyst A was used in all examples to demonstrate the invention.
• a catalyst charge of about 5.4 ml (catalyst size: 20-40 mesh) loaded in a SS-3 16 tube (OD y ⁇ inch,
• Catalyst was dried by slowly raising the catalyst bed temperature (about 5°C/min) to 200°C under hydrogen flow (50 cc/min) for at least one hour. Catalyst was then steamed by introducing water vapor (2.2 mmole/min) with a carrier gas of H 2 (459 cc/min) at 200°C overnight.
• examples 1 -7 after steaming the catalyst toluene, methanol, water and hydrogen were introduced into the reactor at different conditions (temperature and order of introduction) to effect the catalyst performance particularly catalyst deactivation resulting in the yield of p-xylene product. Toluene, methanol, water and hydrogen were fed to the reactor via a preheater at 200°C so that water, methanol and toluene were vaporized and mixed before entering the reaction zone.
• catalyst was steamed at 200°C overnight and then toluene, methanol, water, and hydrogen were introduced into the reactor at 200°C at the rates shown below.
• the reactor temperature was then increased and catalyst bed inlet temperature was adjusted to 485°C which was maintained constant during the test run.
• the reactor streams were analyzed to calculate conversion, selectivity and p-xylene yield shown in Table 1 .
• catalyst was steamed at 200°C overnight in presence of steam and hydrogen. Flows of hydrogen and water were discontinued after steaming the catalyst and reactor temperature was increased to about 480°C at which time hydrogen, water, and premixed toluene and methanol were introduced into the reactor at the rates shown below.
• the catal yst bed inlet temperature was adjusted to 485°C which was maintained constant during the test run.
• the reactor streams were analyzed to calculate conversion, selectivity and p-xylene yield shown in Table 2.

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• 2009
  • 2009-12-08 US US12/653,043 patent/US20110137099A1/en not_active Abandoned
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