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
  • B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
  • B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
  • B01J29/70—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of types characterised by their specific structure not provided for in groups B01J29/08 - B01J29/65
  • B01J29/703—MRE-type, e.g. ZSM-48
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B37/00—Compounds having molecular sieve properties but not having base-exchange properties
  • C01B37/02—Crystalline silica-polymorphs, e.g. silicalites dealuminated aluminosilicate zeolites
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B39/00—Compounds having molecular sieve and base-exchange properties, e.g. crystalline zeolites; Their preparation; After-treatment, e.g. ion-exchange or dealumination
  • C01B39/02—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof; Direct preparation thereof; Preparation thereof starting from a reaction mixture containing a crystalline zeolite of another type, or from preformed reactants; After-treatment thereof
  • C01B39/46—Other types characterised by their X-ray diffraction pattern and their defined composition

Definitions

• This invention relates to a process for the synthesis of zeolites of the ZSM-48 type and their use as a selective organophilic catalyst and adsorbent.
• the zeolites whose structure corresponds to the topology of type ZSM-48, known to date, are EU-2, EU-ll and ZBM-30 (P. Jacobs and J. Martens, Synthesis of high silica aluminosilicate zeolites , Stud. Surf. Sci. Catal., 33, 275, 1987). They are solids of interest for the catalytic transformation of hydrocarbons and organic compounds and for adsorption.
• the synthesis of zeolites of the ZSM-48 type is described in several patents and publications in the scientific literature, the main ones of which are summarized in Table 1.
• the zeolites of the ZSM-48 type are prepared by hydrothermal crystallization of reactive alkaline gels of aluminosilicates or silicates. The syntheses are carried out in the presence of one or more nitrogenous organic agents such as alkylamines, diamines, tertiary, quaternary and bis-quaternary alkyl ammoniums or pyrrolidine.
• nitrogenous organic agents such as alkylamines, diamines, tertiary, quaternary and bis-quaternary alkyl ammoniums or pyrrolidine.
• microporous zeolite is carried out by an oxidative calcination at a temperature generally above 500 ° C.
• This calcination stage has a certain number of drawbacks because, in addition to its energy cost, it can cause degradation of the crystal structure and it is accompanied by the release of nitrogen oxides which it is imperative to treat for environmental reasons.
• the cost of syntheses is increased because the organic agent is generally the most expensive component of the preparation.
• zeolite precursor can be transformed into zeolite without calcination, by a simple moderate heat treatment. This treatment does not lead to degradation of the crystal structure.
• the zeolite obtained has remarkable thermal and chemical stability.
• This mixture is maintained at a temperature above 80 ° C. and under a pressure at least equal to the vapor pressure of the solution for a time sufficient to effect the crystallization of the reaction mixture into a zeolite precursor, then the enzéolite precursor is transformed by removing the glycol and the water retained in the porosity .
• the reaction mixture may optionally contain a source of trivalent aluminum.
• the hydroxide ions are derived from compounds of formula M (OH) n where M is a cation of valence n, n being generally 1 or
• M is generally an alkali metal from group IA of the periodic table, an alkaline earth metal or an organic compound, such as a quaternary ammonium.
• tetravalent silicon which can be used in the preparation of the reaction mixture
• finely divided solid silicas in the form of hydrogels, aerogels or colloidal suspensions, water-soluble silicates such as alkali silicates, hydrolyzable silicic esters such as that orthosilicates, tetraalkyl formula Si (OR) 4 wherein R is alkyl to C 4 such as methyl and ethyl.
• the silicon source is used in the form of a true aqueous solution, in the case of water-soluble silicates, or else of an aqueous suspension which may be colloidal, in the case of finely divided silicates.
• the traces of aluminum present in the silicon source do not interfere with crystallization.
• Aluminum can also be deliberately incorporated into the synthesis in the form of aluminum salts such as sulphate, nitrate, chloride, fluoride, acetate, aluminum oxides and hydroxides, aluminates and in particular alkali alu inates, aluminum esters such as the aluminum trialkoxides of formula Al (OR) 3 in which R denotes a C1 to C4 alkyl radical such as methyl, ethyl, propyl or butyl.
• the mixing of the ingredients constituting the reaction mixture can be carried out in any order.
• an alkaline solution is first prepared by dissolving the strong base in water.
• the strong base is generally potash or soda in pellets.
• To this alkaline solution is added the glycol and then the source of silicon. These two operations are generally carried out at room temperature.
• the whole is transferred to an autoclave.
• the mixture is heated under autogenous pressure until the zeolite has completely crystallized.
• the reaction time is generally between 10 and 150 hours.
• the temperature varies between 80 and 200 ° C.
• the duration of the synthesis can be shortened by adding to the reaction medium crystallization seeds.
• the germs are obtained by grinding a zeolite of the ZSM-48 type.
• the crystals obtained are the precursor of the zeolite consisting of the zeolite trapping in its pores and cavities the water of hydration, cations and glycol. These crystals are separated from the reaction medium by filtration, washed with distilled or deionized water, until washing waters are obtained at neutral pH. The washed crystals can then be dried at a temperature between room temperature and 90 ° C, preferably around 70 ° C.
• the stoichiometric composition of the zeolite precursor expressed in moles of oxides is as follows: a M g. b AI 2 O 3 . Si ⁇ 2 . cH 2 ⁇ .dG n where - M is a cation with valence n, in general an alkali metal from group IA of the Periodic Table of the Elements, an alkaline earth metal or a quaternary ammonium. M is preferably potassium or sodium. G is a glycol molecule.
• the X-ray diffractogram was obtained by a conventional method using K alpha copper radiation and an amplifying detector.
• the signal intensities are recorded as a function of their position expressed in two theta, where theta is the Bragg angle.
• d (nm) the reticular distances
• the values may differ slightly depending on the size of the crystals and their hydration state, but in general the X-ray diffractogram is a characteristic of the structure concerned.
• the zeolite is obtained from the precursor by liberation from its cavities and channels.
• the cavities and channels contain nitrogenous organic bases.
• the porosity can only be released by calcination, by thermally degrading the structuring molecules.
• the porosity of the ZSM-48 zeolite prepared according to the invention is released by treatments at moderate temperature, sufficient to cause the departure of the water and glycol molecules. A simple air drying is sufficient.
• ethylene glycol is particularly advantageous because it can be removed by drying at a temperature below 200 ° C.
• the zeolite thus obtained has an X-ray diffraction spectrum substantially equal to that of the precursor, except for some variations in intensity of the peaks at small angles.
• the crystallinity and the adsorption capacities of the zeolite are retained after heat treatment and hydrothermal prolonged or after treatment with acid or basic solutions.
• the zeolite Before use, the zeolite can be subjected to a treatment aimed at eliminating traces of cations, generally alkaline cations which may be present.
• the zeolites obtained according to the invention are suitable as organophilic adsorbents, allowing the separation of "organic molecules from water.
• EXAMPLE 1 This example describes a general method for preparing a zeolite of the ZSM-48 type according to the invention and its use as an adsorbent.
• the solid presents an X-ray diffractogram corresponding to that of Table 3.
• This zeolite adsorbs 0.1% by weight of water (5 torr, 25 ° C), and 4.7% by weight of methanol (15 torr, 25 ° C).
• the zeolite After calcination under air flow at 850 ° C for ten hours, the zeolite retained its crystallinity, evaluated by X-ray diffraction, and its specific surface at
• the solid has an X-ray diffractogram corresponding to that of Table 3.
• the weight of solid, dried at 70 ° C, obtained in this synthesis, is 7.6 grams which corresponds to a yield relative to the silica used for 72%.
• This example illustrates a synthesis of zeolite according to the invention in which the content of ethylene glycol in the starting gel and the crystallization temperature have been reduced.
• the solid presents an X-ray diffractogram corresponding to that of Table 3.
• the weight of solid, dried at 70 ° C., collected in this synthesis is 27.4 grams, which corresponds to a yield relative to the committed silica of 89%.
• This example illustrates a synthesis of zeolite according to the invention from a medium richer in aluminate.
• KOH potassium hydroxide
• Al (OH) 3, Merck aluminum hydroxide
• a 200 ml stainless steel autoclave containing 41 ml of deionized water.
• 66 g of ethylene glycol Labosi for analyzes
• 9.2 g of silica Si ⁇ 2, Aerosil Serva
• the composition of the crystallization gel obtained is as follows 0.16 K2O, 0.005 AI2O3, SiO2, 15 H2O, 7 C2H4 (0H) 2
• the solid has an X-ray diffractogram corresponding to that of Table 3.
• EXAMPLE 5 This example illustrates a synthesis of zeolite according to the invention from a medium in which the ethylene glycol has been replaced by diethylene glycol and in the absence of stirring during crystallization.
• the solid has an X-ray diffractogram corresponding to that of Table 3.
• EXAMPLE 6 This example illustrates a synthesis of zeolite according to the intervention from a medium in which the ethylene glycol has been replaced by triethylene glycol.
• the solid has an X-ray difractogram corresponding to that of Table 3.
• the weight of solid, dried at 70 ° C., collected in this synthesis is 2.68 grams, which corresponds to a yield relative to the committed silica of
• catalytic activity of zeolites according to the invention was evaluated as a fresh additive of an industrial FCC catalyst, called in short ECAT (for Equilibrium
• Example 3 The additive obtained in Example 3 is mechanically mixed in an amount of 5 and 10% by weight with the ECAT catalyst.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Life Sciences & Earth Sciences (AREA)
• General Life Sciences & Earth Sciences (AREA)
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• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Materials Engineering (AREA)
• Inorganic Chemistry (AREA)
• Crystallography & Structural Chemistry (AREA)
• Silicates, Zeolites, And Molecular Sieves (AREA)
• Catalysts (AREA)

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• 1992
  • 1992-12-08 FR FR9214776A patent/FR2698863B1/fr not_active Expired - Fee Related
• 1993
  • 1993-12-07 CA CA 2129662 patent/CA2129662A1/fr not_active Abandoned
  • 1993-12-07 EP EP94901992A patent/EP0625125A1/de not_active Withdrawn
  • 1993-12-07 WO PCT/FR1993/001200 patent/WO1994013583A1/fr not_active Application Discontinuation
  • 1993-12-07 JP JP6513858A patent/JPH07503699A/ja active Pending

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