Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J29/00—Catalysts comprising molecular sieves
  • B01J29/82—Phosphates
• • 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
• • 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
  • B01J29/82—Phosphates
  • B01J29/84—Aluminophosphates containing other elements, e.g. metals, boron
  • B01J29/85—Silicoaluminophosphates [SAPO compounds]
• • 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
• • 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
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2229/00—Aspects of molecular sieve catalysts not covered by B01J29/00
  • B01J2229/10—After treatment, characterised by the effect to be obtained
  • B01J2229/18—After treatment, characterised by the effect to be obtained to introduce other elements into or onto the molecular sieve itself
• • 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
  • B01J2229/37—Acid treatment
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2229/00—Aspects of molecular sieve catalysts not covered by B01J29/00
  • B01J2229/30—After treatment, characterised by the means used
  • B01J2229/42—Addition of matrix or binder particles
• • 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 the alkylation of aromatic compounds and catalysts used for such reactions and their preparation.
• Para-xylene is a valuable substituted aromatic compound because of its great demand for its oxidation to terephthalic acid, a major component in forming polyester fibers and resins. It can be commercially produced from hydrotreating of naphtha (catalytic reforming), steam cracking of naphtha or gas oil, and toluene disproportionation.
• 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 0 C. Such toluene methylation may occur over a wide range of temperatures, however. Byproducts such as C9+ and other aromatic products can be produced by secondary alkylation of the xylene product.
• Para-xylene can be separated from mixed xylenes by a cycle of adsorption and isomerization. Such cycle may have to be repeated several times because of the low isomeric concentration in the equilibrium mixture.
• a high purity grade (99+%) p-xylene is desirable for its oxidation to terephthalic acid.
• the production cost for such a high purity grade p-xylene can be very high, however.
• a different method that employs crystallization techniques can be used and may be less expensive where the concentration of p-xylene is around 80% or higher in the initial xylene product. Thus, higher than equilibrium concentrations of p-xylene may be desirable.
• a significantly higher amount of p-xylene can be obtained in toluene methylation reaction if the catalyst has shape selective properties.
• Shape selective properties can be obtained in modified zeolite catalysts by narrowing zeolite pore opening size, inactivation of the external surface of the zeolite or controlling zeolite acidity. Toluene methylation may occur over modified ZSM-5 or ZSM-5-type zeolite catalyst giving xylene products containing significantly greater amounts of p-xylene than the thermodynamic concentration.
• FIGURE 1 shows 31 P MAS-NMR spectrum for phosphorus-modified ZSM-5 zeolite Catalyst A; ⁇
• FIGURE 2 shows 31 P MAS-NMR spectra for Catalysts I (spectrum a) and K
• FIGURE 3 shows 31 P MAS-NMR spectra for a phosphorus-modified ZSM-5 zeolite (spectrum a) precursor used for preparing Catalysts L and M, and for an alumina bound phosphorus-modified ZSM-5 zeolite — Catalyst M (spectrum b);
• FIGURE 4 is a plot of toluene conversion over time for the toluene methylation reaction for Catalyst L of Example 14;
• FIGURE 5 is a plot of methanol selectivity (curve 1), mixed-xylene selectivity
• FIGURE 6 is a plot of toluene conversion over time for the toluene methylation reaction for Catalyst M of Example 15;
• FIGURE 7 is a plot of methanol selectivity (curve 1), mixed-xylene selectivity
• FIGURE 8 is a plot of toluene conversion over time for the toluene methylation reaction for Catalyst A of Example 16.
• ZSM-5 zeolite is one of the most versatile catalysts used in hydrocarbon conversions. It is a porous material containing intersecting two-dimensional pore structure with 10-membered oxygen rings. Zeolite materials with such 10-membered oxygen ring pore structures are often classified as medium-pore zeolites. Modification of ZSM-5-type zeolite catalysts 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. Such modification has been shown to provide selectivity for p-xylenes of greater than 80%.
• ZSM-5-type is meant to refer to those zeolites that are isostructurally the same as ZSM-5 zeolites. Additionally, the expressions "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.
• 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:
• Mole% p-Xylene Selectivity (X p ZX 1x ) x 100 (4) where, X p is the number of moles of p-xylene.
• M 1 - 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 [XJ(MrM 0 )] x 100 (6) where, X tx is the number of moles of mixed (o-, m- or p-) xylenes, Mj is the number of moles of methanol fed and M 0 is the number of moles of unreacted methanol.
• the ZSM-5 zeolite catalysts and their preparation are described in U.S. Patent No. 3,702,886, which is herein incorporated by reference.
• the ZSM-5 zeolite catalyst may include those having a silica/alumina molar ratio of 200 or higher, more particularly from about 250 to about 500 prior to modification.
• the starting ZSM-5 may be an NH 4 + or H + form and may contain traces of other cations.
• the ZSM-5 may be modified by treating with phosphorus-containing compounds.
• phosphorus-containing compounds may include, but are not limited to, phosphonic, phosphinous, phosphorus and phosphoric acids, salts and esters of such acids and phosphorous halides.
• phosphoric acid (H 3 PO 4 ) and 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 selective properties to provide increased p-xylene selectivity.
• 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 0.13 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 0.11 g P/g zeolite.
• P phosphorus
• the phosphorus-treated zeolite may be dried.
• Suitable binder materials may include inorganic oxide materials. Examples of such materials include alumina, clay, aluminum phosphate and silica-alumina. In particular, a binder of alumina or clay or their combinations are particularly useful.
• the bound catalyst may contain from about 1% to about 99% by total weight of bound catalyst, more particularly from about 10% to about 50% binder by total weight of bound catalyst.
• the binder material may be combined with the phosphorus-treated zeolite to form an extrudable mixture.
• the P-treated zeolite bound with the binder may be calcined or heated at a temperature of 400 0 C or higher, more particularly at a temperature between 500 °C and 700 0 C. Such heating may be carried out for 0.5 hours or more to form the bound catalyst. It has been discovered that heating the P-treated ZSM-5 at a temperature of about 300 0 C or higher and then binding the zeolite with a suitable binder, as described herein, may result in the bound zeolite exhibiting multiple P-species, as shown by 31 P MAS NMR peaks.
• the bound zeolite catalyst may exhibit at least two peaks having maxima at from about 0 ppm to about —55 ppm. More particularly, the bound zeolite catalyst may exhibit a 31 P MAS NMR peak having a maximum at from about 0 ppm to about -25 ppm, more particularly at from about -5 ppm to about -20 ppm, and another with a maximum at from about -40 ppm to about -50 ppm. Such peaks are an indication of various phosphorus species. In particular, a 31 P MAS NMR peak with maximum of about -44 ppm may be indicative of polyphosphate species.
• a peak with a maximum at from about 0 ppm to about -25 ppm may be indicative of phosphorus bound by extra- framework aluminum or amorphous alumina.
• Aluminophosphates (AlPO 4 ) and silicoaluminophosphates (SAPO) may be indicated by a peak with a maximum at around -28 ppm to about -35 ppm.
• Free phosphates may be indicated by a peak with a maximum at around 0 ppm.
• the P-modified ZSM-5 catalyst, bound or unbound, may be mildly steamed at a temperature of 300 0 C or lower before using the catalyst in any reaction.
• the steaming can be carried out in-situ or ex-situ of the reactor.
• the use of catalyst steaming at mild temperatures is described in co-pending U.S. patent application Serial No. 11/122,919, filed May 5, 2005, entitled "Hydrothermal Treatment of Phosphorus-Modified Zeolite Catalysts," which is herein incorporated by reference.
• the P-modified ZSM-5 catalyst bound or unbound, may be contacted with an appropriate feed of an aromatic hydrocarbon and an alkylating agent under alkylation reaction conditions to carry out aromatic alkylation.
• the catalyst has particular application for use in toluene methylation utilizing a toluene/methanol feed.
• a gas cofeed may also be used.
• the cofeed gas may include hydrogen or an inert gas.
• alklyation 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 as cofeed along with the alkylation feed.
• the water or steam used for the methylation 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 up.
• liquid water may be added and vaporized prior to its mixing with cofeed gas (if any) and the alkylation feed.
• the use of water cofeed is described in U.S. Patent App. Publication No. US2005/0070749 Al, published March 31, 2005, and entitled "Toluene Methylation Process," which is herein incorporated by reference.
• 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 1 °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 catalyst bed of the reactor.
• the 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.
• the P-modified ZSM-5 zeolite catalyst as described herein, has particular application for use in toluene methylation for preparing a xylene product from a feed of toluene and methanol.
• the catalyst provides increased selectivity for p-xylene when used in toluene methylation.
• the catalyst may provide greater than 85%, 90% or 95% para-xylene selectivity when used in toluene methylation.
• the P/ZSM-5 catalyst described herein, bound or unbound may provide steady catalyst activity and selectivity for toluene methylation over periods of 25 days, 30 days, 60 days or more under appropriate reaction conditions.
• the catalyst may be contacted with a methylation feed and gas cofeed at a suitable temperature to give a desired toluene conversion.
• the desired toluene conversion was 63% of theoretical maximum toluene conversion using a methylation feed containing a toluene/methanol molar ratio of about 4.5.
• the reaction was carried out at a constant reactor temperature over the test period.
• a binder-free, P-modified ZSM-5 (P/ZSM-5) was prepared.
• the starting zeolite powder was an NH 4 -ZSM-5 powder having Si(VAl 2 O 3 mole ratio of 280.
• a slurry containing 700 g of NH 4 -ZSM-S zeolite and 700 ml of water was prepared in a 2-L beaker. The beaker was placed on a hot plate and the zeolite slurry was stirred using a mechanical (overhead) stirrer with 250-300 rpm. The temperature of the slurry was slowly raised to about 80-85 °C.
• a phosphoric acid solution containing 319 g of phosphoric acid (Aldrich, 85 wt% in aqueous) was slowly added to the slurry.
• the slurry temperature was further increased to between 95-100 0 C and heating was continued until all liquid was evaporated.
• the phosphoric-acid modified zeolite was then heated in a convection oven in air at the following temperature program: 90°C to 120 °C for three hours, at 340 °C to 360 0 C for three hours and at 510 0 C to 530 0 C under air for 10 hours.
• the resulting heat-treated zeolite (Catalyst A) was then crushed and sized using 20 and 40 mesh screens for catalytic reaction or sieved through 80 mesh screen for binding the zeolite with a binder.
• Catalyst A was analyzed for Si, Al and P by X-ray fluorescence (XRF), and for BET surface area and total pore volume by N 2 adsorption. As shown in Table 1, Catalyst A contained 35.73 wt% Si, 0.28 wt% Al and 9.01 wt% P, and had a BET surface area of 160 m 2 /g and total pore volume of 0.12 ml/g. The X-ray diffraction pattern for Catalyst A was recorded on a Philips (X'Pert model) diffractometer over a range of 5-55° at a scan rate 2° per minute using CuK ⁇ l radiation. The results are presented in Table 2.
• Solid state Magic Angle Spinning (MAS) NMR spectra were recorded on Catalyst A with 400 MHz spectrometer ( 27 Al at 104.5 MHz) at room temperature ( 27 Al MAS NMR). Samples were packed in silicon nitride rotors (Si 3 N 4 ) and spun at 13 to KHz sample spinning (about 800000 rpm). A lO degree tip and recycle delay of 0.5s were used to avoid saturation. About 4000 to 10000 scans were accumulated to signal average and improve signal/noise ratio. Proton decoupling was not employed. All spectra were referenced to aluminum chloride hexahydrate (run separately in a tube) at 0.0 ppm on the chemical shift scale.
• the Catalyst A sample shows a weak peak at 55-50 ppm region assigned to structural tetrahedral aluminum.
• the tetrahedral aluminum peak is severely distorted, indicating the presence of nested silanols caused by holes in the structure upon removal of some of the framework aluminum.
• the adjacent peak (30-40 ppm) peak is due to severely distorted but still in the framework aluminum atoms probably either in the 3 or 5 coordination with oxygens.
• Solid state Magic Angle Spinning (MAS) NMR spectra were recorded on Catayst A with 400 MHz spectrometer ( 31 P at 161.7 MHz) at room temperature ( 31 P MAS NMR). Samples were packed in silicon nitride rotors (Si 3 N 4 ) and spun at 13 to KHz sample spinning (about 800000 rpm). A 30 degree tip and recycle delay of 15s were used to avoid saturation. About 4000 to 10000 scans were accumulated to signal average and improve signal/noise ratio. Proton decoupling was not employed.
• FIG. 1 illustrates 31 P MAS NMR spectrum for a P/ZSM-5 zeolite (Catalyst A).
• the 31 P MAS NMR spectrum for Catalyst A shows peaks at 0, -11, -31 and -44 ppm attributed to various P-species such as free phosphorus and phosphorus bonded (via oxygen) to Si and Al.
• Catalyst A was bound with 20% aluminum phosphate.
• Catalyst A was bound with aluminum phosphate, available from Aldrich Chemicals, as a binder following the same procedure as described for Catalyst B.
• the resulting Catalyst D was crushed and sized using 20 and 40 mesh screens for catalytic test.
• Catalyst A was bound with 20% kaolin.
• P/ZSM-5 was bound with kaolin as binder following the same procedure as described for Catalyst B.
• Kaolin aluminum silicate hydroxide
• the resulting Catalyst E was crushed and sized using 20 and 40 mesh screens for catalytic test.
• Catalysts A-E were used in toluene methylation.
• the reactions were each carried out in a fixed bed, continuous flow type reactor.
• a catalyst charge of 5.4 ml (catalyst size: 20-40 mesh) was loaded in the reactor.
• the 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.
• the catalyst was steamed by introducing water vapor (2.2 mmole/min) with a carrier gas of H 2 (459 cc/min) at 200 0 C overnight.
• a premixed toluene and methanol feed (molar ratio 4.5) was added to the reactor at 200 °C and the catalyst bed inlet temperature was increased to about 550 °C.
• the liquid hourly space velocity (LHSV) (based on methylation feed) was maintained at about 2 hr "1 and a cofeed H 2 gas was fed and maintained to provide a H 2 /methylation feed molar ratio of about 7-8.
• water was added to the reactor as cofeed and was vaporized prior to introduction to the reactor.
• the H 2 O/methylation feed molar ratio was about 0.8 and the reactor pressure was about 20 psig.
• Reactor streams were analyzed to calculate conversion and selectivity. Liquid product stream analyses and conversion and selectivity for toluene methylation reaction over Catalysts A-E are shown in Table 3 below.
• Catalyst A NH 4 -ZSM-5 having a Si(VAl 2 O 3 molar ratio of 280 was treated with H 3 PO 4 acid. The H 3 PO 4 acid treated ZSM-5 was then heated at 510-530°C for approximately 10 hrs. Three alumina bound catalysts were made using the resulting P/ZSM-5 powder with 10 wt% alumina (Alcoa HiQ40) as binder and each was further calcined or heated at different maximum temperatures to form Catalysts F-H. Catalyst F was heated at a maximum temperature of 400 0 C. Catalyst G was heated at a maximum temperature of 510 0 C.
• Catalyst H was heated at a maximum temperature of 600 °C.
• the catalysts were tested for toluene methylation using the conditions described in Examples 1-5.
• Table 4 shows the liquid product stream analysis and conversion and selectivity for Catalysts F-H for Examples 6-8.
• NH 4 -ZSM-5 having a Si(VAl 2 O 3 molar ratio of 280 was treated with H 3 PO 4 acid.
• the H 3 PO 4 acid treated ZSM-5 was then heated at different temperatures of 90 0 C, 250 0 C or 320 °C.
• the heat-treated, P- modified ZSM-5 zeolite powder was then combined with 20 wt% alumina (Alcoa HiQ40) following the same procedure described for Catalyst B, and was calcined or heated at a maximum temperature of from 510 to 530 0 C.
• Catalysts I, J and K were tested for toluene methylation using the conditions described for Examples 1-5.
• the 31 P MAS NMR spectra for Catalysts I and K are shown in Figure 2.
• the 31 P MAS NMR spectrum for Catalyst I shows only a single peak at around -30 ppm with a long tail ( Figure 2 spectrum a).
• Figure 2 spectrum a shows additional peak(s), including a peak at around -44 ppm (see, for example, spectrum b of Figure 2 and spectrum b of Figure 3).
• Table 5 summarizes the initial heating temperature of the unbound P/ZSM-5 and catalytic test results obtained for bound Catalysts I-K. Also, the data for Catalyst B reproduced from Table 3 is presented in Table 5 for comparison. Those catalysts made from the P-modified ZSM-5 zeolite that were heated at a temperature of 300 0 C or higher and then bound with a suitable binder showed 90% or higher p-xylene selectivity for toluene methylation.
• the P/ZSM-5 zeolite that was heated at a temperature of about 300°C or above, and then bound with alumina followed by calcinations or heating at 500 0 C above showed increased shape selectivity producing p-xylene selectively for toluene methylation.
• Higher activity with decreased p-selective catalyst can be achieved by heating the P/ZSM-5 at 300 0 C or less and binding with alumina and calcining or heating at 500°C or higher.
• the P/ZSM-5 zeolite was bound with 20% alumina (pseudobohemite type) and extruded to make 1/16-inch cylindrical shape catalyst.
• Alcoa alumina grades HiQ-40 and HiQ-IO were used for Catalyst L and M, respectively.
• Catalysts L and M were calcined or heated at a maximum temperature between 510 °C and 530 0 C.
• Figure 3 shows a 31 P MAS NMR spectrum (spectrum b) for an alumina bound catalyst - Catalyst M.
• the 31 P MAS NMR spectrum for Catalyst M shows two strong peaks at around -13 ppm (broad peak) and -44 ppm. This differs significantly from the 31 P MAS NMR spectrum for Catalyst I, as shown in Figure 2 (spectrum a).
• Catalyst L and M were tested for toluene methylation.
• the reactor, catalyst charge, catalyst drying and steaming procedure were the same as described in Examples 1-5, and the reaction conditions were the same as in Examples 1-5.
• Reactor liquid product stream analysis and conversion and selectivity for Catalysts L and M are shown in Tables 9 and 10, respectively. Under the reaction conditions used for toluene methylation, Catalysts L and M showed initial 14% toluene conversion (63% of theoretical maximum) with greater than 98% mixed-xylene and 96% p-xylene selectivity.
• Trimethylbenzenes 0.1 0.1 0.2 0.2 0 0.2 0.2
• Catalyst L was further tested for catalyst stability in toluene methylation reaction.
• the reactor and feed conditions were the same as those described in Examples 1-5.
• the catalyst was steamed overnight at 200 0 C.
• a premixed toluene and methanol feed (molar ratio 4.5) was added to the reactor at 200 0 C.
• the liquid hourly space velocity (LHSV) (based on methylation feed) was maintained at about 2 hr '1 and a cofeed of H 2 gas was fed and maintained to provide a H 2 /methylation feed molar ratio of about 7-8.
• water vapor was added to reactor as cofeed.
• the H 2 O/methylation feed molar ratio was about 0.8 and the reactor pressure was about 20 psig.
• the catalyst bed inlet temperature was increased slowly to about 510 0 C over a period of time to give toluene conversion of about 14%, and no reactor temperature adjustment was made during the test period of 637 h (26 days).
• Toluene conversion, and selectivities to mixed xylene, p-xylene and methanol are shown in Figures 4 and 5.
• Catalyst M was further employed to show stable catalytic performances for toluene methylation reaction.
• the reactor, catalyst charge, catalyst drying and steaming procedure were the same described for Examples 1-5. After drying the catalyst at 200 0 C, the catalyst was steamed overnight at about 200 0 C.
• a premixed toluene and methanol feed (molar ratio 4.5) was added to the reactor at 200 °C.
• the liquid hourly space velocity (LHSV) (based on methylation feed) was maintained at about 2 hr '1 and a cofeed of H 2 gas was fed and maintained to provide a H 2 /methylation feed molar ratio of about 7-8.
• water vapor was added to reactor as cofeed.
• the H 2 O/methylation feed molar ratio was about 0.8 and reactor pressure was about 20 psig.
• the catalyst bed inlet temperature was increased slowly to 535 0 C over a period of time to give toluene conversion of about 14%, and no further reactor temperature adjustment was made during the test period of 1560 h (64 days).
• Toluene conversion, and selectivities to mixed xylene, p-xylene and methanol are shown in Figures 6 and 7.
• Catalyst A was employed to test its stable activity for toluene methylation.
• the reactor, feed composition, catalyst drying and steaming conditions were the same as described for Examples 1-5. After drying the catalyst at 200 °C, the catalyst was steamed overnight at 200 °C.
• a premixed toluene and methanol feed (molar ratio 4.5) was added to the reactor at 200 0 C.
• the liquid hourly space velocity (LHSV) (based on methylation feed) was maintained at about 2 hr "1 and a cofeed H 2 gas was. fed and maintained to provide a H 2 /methylation feed molar ratio of about 7-8.
• water was added to the reactor as cofeed and was vaporized prior to introduction into the reactor.
• the H 2 O/methylation feed molar ratio was about 0.8 and the reactor pressure was about 20 psig.
• the catalyst bed inlet temperature was slowly raised to 492 0 C when a toluene conversion of about 14% was obtained and when no further reactor temperature adjustment was made during the test period.
• Reactor streams were analyzed to calculate conversion and selectivity.
• Figure 8 shows steady toluene conversion as a function of time on stream.
• the unbound P/ZSM-5 catalyst (Catalyst A) showed stable performance during the test period of 726 hours (30 days).
• Table 11 presents the average toluene conversion, methanol selectivity, mixed-xylene selectivity and p-xylene selectivity for Catalysts A, L and M. Contrasted to the unbound P/ZSM-5 (Catalyst A), the alumina bound catalysts showed at least 5% increased p-xylene selectivity.

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