CS211981B1 - Process for preparing crystalline zeolites - Google Patents

Abstract

The invention relates to a method for the preparation of crystalline zeolites of the ZSM type, which consists in the hydrothermal treatment of a reaction mixture of SiO2 in the form of silica sol or water glass or aluminosilicate, sodium aluminate or other aluminum salt with the addition of amines, alkanolamines in a suitable molar ratio, either separately or in combination with catalytic metal substances. Crystallization takes place at pH 7 to 12 at a temperature of 90 to 220 °C and a pressure of 0.01 to 30 MPa for a period of 1 to 100 days. The crystalline zeolite is then dried, shaped and calcined. Crystalline zeolites suitable for use in catalytic and adsorption processes are obtained.

Description

The present invention relates to a process for the preparation of crystalline ZSM-type zeolites which consists in hydrothermally treating a SiO 2 reaction mixture in the form of silica sol or waterglass or aluminosilicate, sodium aluminate or other aluminum salt with the addition of amines, alkanolamines in suitable relative molar. ratio, either alone or in conjunction with catalytic metal substances. Crystallization takes place at pH 7 to 12 at a temperature of 90 to 220 ° C and a pressure of 0.01 to 30 MPa for 1 to 100 days. The crystalline zeolite is then dried, formed and calcined.

Crystalline zeolites are obtained which are suitable for use in the catalytic and desorption processes.

The present invention relates to a process for the preparation of crystalline ZSM zeolts by hydro-thermal treatment with a SIO2 reaction mixture in the form of slicasol or waterglass or aluminosilicate, sodium aluminate or other aluminum salt with the addition of amines, alkanolamines in suitable molar ratios either alone or in conjunction with catalytic metal substances.

The crystalline aluminosilicates referred to as ZSM are extremely stable synthetic aluminosilicates of the general composition:

0.9 to 0.2 H _{2 / n} O: Al ₂ O 3: 5 to 100 SiO ₂ : zH ₂ O, where M = at least one cation, n = its valence, z = 0 to 40.

M is usually selected from the group consisting of a mixture of alkali metal cations, especially sodium, and tetraalkylammonium cations of alkyl groups, preferably containing 2 to 5 hydrocarbon atoms. The original cations can be replaced, depending on the preparation technique used, either partially or completely by other cations by ion exchange. Cation exchange includes, in particular, tetraalkylammonium cations, metal ions, ammonium tones, hydrogen ions, and mixtures thereof.

Particularly suitable are cations which give the zeolite catalytic activity for hydrocarbon conversion. These include in particular hydrogen, rare earth metals, aluminum, metals II., IV., VI. and VIII. SiO2 / Al2O3 molar ratio is (ranging from 10 to 200 for ZSM and these zeolts are characterized by a particularly high degree of thermal stability, which allows them to be used in elevated temperature processes. ZSM type zeolts have a defined crystalline ^{1 is a} structure distinguishable by X-ray diffraction determined (defined by a standard technique using copper alpha-doublets) and subtracting the Brag angle on a spectrometer.

ZSM-type zeolites are usually prepared from solutions of tetraethylammonium hydroxide or tetraethylammonium bromide together with Na ₂ O, Al ₂ O 3, S ₁ O ₂ and water, the components being in a ratio suitable for forming reaction mixtures within about the following range:

SÍCVAI2O3 5 to 100

Na 2 O / tetraalkylammonium hydroxide 0.5 to 0.20 tetraalkylammoniumhydroxide / SiO 2 0.08 to 1.0

H (3) tetraalkylammonium hydroxide 80 to 200

The reaction mixture thus formed is heated at a suitable temperature and pressure for several days to form a crystalline form, whereupon the reaction product is separated from the mother liquor, filtered, washed and heat treated. The size and shape of the crystals as well as the crystallization time depend to a large extent on the composition of the starting reaction mixture and the operating conditions used in the crystallization.

Since the use of some of the starting materials for the preparation of ZSM zeolites, such as tetraalkylammonium compounds, is relatively expensive and not always available, simpler and more cost-effective processes for preparing crystalline zeolts are still sought.

It has now been found that crystalline ZSM-type zeolts can be prepared from a reaction mixture containing a small amount of organic nitrogen compounds readily available commercially, such as amines or alkanolamines, using a low ratio of hydroxide to SiO 2 while seeding the starting reaction mixture with zeolite crystals. previous production batch. It therefore has no shortcomings. A method for preparing crystalline zeolites by heat treating a mixture comprising _SiO2, Al2O3, alkali, H2O, and amines of this invention whose principle consists in that the reaction mixture alumlnátu sodium or inorganic or organic aluminum compound together with sillkasolem containing less than 1% Na ₂ 0 or waterglass moíárním sulfate with an SiO2: Al2O3 in the range from 10 to 200 and moíárním ratio Na ₂ O: SiO 2 0.01 to 2.0 ,, with the addition of an alkylamine or alkanolamlnů moíárním ratio to SiO2 of from 0.01 to 2.0 at pH 7 12 to 12 are crystallized at a temperature of 90 to 220 [deg.] C. and a pressure of 1 to 100 bar for 1 to 100 days, after which the crystalline zeolite formed is dried at 100 to 200 [deg.] C. after washing the alkali to below 1%. Anneals at 400 to 750 ° C. 0.1 to 20% of crystalline ileorite produced in over-batches may be added to the initial reaction mixture prior to heat treatment.

An advantage of the present invention is that the reduction of the organic sulfur content of the obtained crystalline zeolite is achieved by seeding the starting reaction mixture with zeolite crystals from a previous batch, or by adding alcohol with NHiOH, or by adding hexamethylene, dlamine, monoethanolamine, monopropanolamine However, sodium or ammonium salts of sulfonic fatty acids, arylalkylsulfonates, alkylethanolamine salts, etc. may be added to the reaction mixture to provide a crystalline zeolite with a low nitrogen content, usually by alkali metal exchange. Na ⁺ , hydrogen Ή + or ammonium NH4 ⁺ or another metal without the use of previous calcination.

The zeolite thus produced may be contaminated with a salt solution of the desired cation, in particular in a combination of hydrogenation active elements such as tungsten, molybdenum, nickel, cobalt, chromium, platinum, rent, palladium etc. in the form of their salt solutions and the like. alkali content, in particular Na ₂ O to adjust pH of the initial reaction mixture to a value of 7-12, or the addition of nitrate or aluminum sulfate or acids, e.g. H2SO4, HNO3, H3PO4, HC1, HF, H3BO3, or organic acids, e.g. HCOOH, CH 3 COOH etc. Addition of various salts, such as

Na ₂ SO ₄ , NaNO ₃ , NaF, NaCl, Na ₃ PO ₄ , Na-acetate, etc. shortens the time required for crystallization.

Typical operating conditions for preparing said crystalline zeolites are to prepare the reaction mixture from the starting components, which are sodium aluminate prepared by dissolving aluminum hydrate in aqueous NaOH, or dissolving aluminum sulfate or aluminum chloride or aluminum nitrate, or other aluminum compounds such as e.g. alkylaluminum alkoxides, which connection with e.g. a technical waterglass, sodium or sllikasolem alkallí or simply containing Na ₂ O less than 1% formed thin (suspension to which '(added imiono- or diethanolamine or hexametylendlamin, propylnebo isopropylamine and thinned with water whereupon the resulting suspension is mixed thoroughly to form a homogeneous paste, usually at a pH of 7-12, to which a suitable amount, preferably 1-10%, of zeolite crystals from the previous batch is added.

The resulting suspension is poured into a suitable vessel equipped with stirring and heating. The reaction mixture is maintained at a temperature of 90 to 220 ° C, preferably 150 to 175 ° C and a pressure of 1 to 100 MPa for 1 to 100 days, preferably 24 to 150 h, with occasional stirring of the reaction mixture.

The gel is digested until a crystalline form of the zeolite is formed, which largely depends on the strength of the starting reaction mixture, the temperature used and the time of crystallization.

After crystallization is complete, the reaction mixture is allowed to cool, filtered and washed with either water or dilute hydrochloric acid, nitric acid or NH ₄ OH, NH ₄ NO ₃ , NH ₄ C1 etc. Alkali washed wet cake only partially or below 1% Na ₂ O It is dried or first saturated with catalytic substances, formed and further heat treated.

Either the wet cake from the filter or, after drying, the powdered product containing 20 to 30% H ₂ O either directly or after saturation with catalytic substances can be formed by tableting or extrusion and the like, or first treated with an appropriate amount of amorphous SiO 2 either silica or slag or hydrate aluminum, alumina and the like, and then only in admixture with these components.

The crystalline zeolite is dried at 100 to 200 ° C and calcined at 350 to 750 ° C for 2 to 48 hours. Also, the zeolite can be subjected to heat treatment using steam at 400 to 750 ° C and an inert gas.

An 11 is used in the heat treatment of the crystalline zeolite of lower temperature, e.g. 180 to 400 ° C, then a pressure of 1 to 20 MPa should be selected. The composition of the prepared crystalline zeolite and its crystalline form largely depend on the ratio of the individual components of the starting reaction mixture. The starting reaction mixture can be prepared either batchwise or continuously. The molar ratio of SiO ₂ / / Al ₂ O ₃ can range from 10 to 200 mol. Na ₂ O / SiO ₂ ratio in the range 0.01 to 2.0 mol. an H ₂ O / SiO ₂ ratio ranging from 10 to 500 moles, a ratio of alkylamines or alkanolamines to SiO ₂ in the range of 0.01 to 2.0.

When seeding the reaction mixture with zeolite crystals produced from the previous batch, the amount of added crystals is in the range of 0.1 to 20% based on the mass of the product produced, or the added amount of amines or alkanolamines is 0.01 to 20% based on SiO ₂ .

The thermal treatment of the reaction mixture is usually carried out for 2 to 5 days to form crystals of the desired form. The solid product is separated from the mother liquor and the remaining mother liquor after treatment can be reused. The solid product obtained is washed with water or an ion exchange technique using a wide variety of salts, in particular chlorides, nitrates or sulphates and the like. The solid product is then washed with water, dried and calcined. By replacing Na + in the synthesized form of the zeolite with the cations H ⁺ or NH ₄ ⁺ , the specific arrangement of Al, Si and O atoms, which form the basic form of the crystalline lattice of the zeolite, practically does not change.

The aluminosilicates thus prepared may be in the form of powder, granules, extrudates, tablets, etc. However, they may be formed into various shapes after perfect homogenization with other materials such as clay, bentonite, kaolin, amorphous SiO ₂ gel, alumina.

These materials, such as clays, diatomaceous earth, alumina hydrogels, sillkasols, act as catalyst binders and serve to increase the strength and abrasion of the formed catalyst, but may have Italian identification measures affecting properties, activity and selectivity (catalysts, especially in larger quantities.

Various porous materials can be used for this purpose, such as aluminosilicates, powdered siloxides, SlO ₂ -TiO ₂ , Al ₂ O ₃ -TiO ₂ in the form of cogels, etc. The relative amounts of these powdered oxides or oxidic gels used as matrix can vary from 1 to 90 %. The crystalline zeolites may be formed either separately in powder or gel tabletting or extrusion formulations, or may be molded in admixture with an aluminum hydrogel filter press, silica sol or silica gel, together with a catalyst composition comprising alumina, molybdenum, tungsten, nickel, cobalt or with natural silicates such as diatomaceous earth, clay, kaolin, with the addition of organic or inorganic acids for peptization and the like.

Mixtures of co-Mo-ALCh catalyst or W-Ni-AhCb catalyst or Ni-Mo-AhCb catalyst may also be formed with the addition of crystalline zeolite. The crystalline zeolite may be added to the slurry during precipitation or to the slurry tank to the precipitated crystalline mass of Co-Mo catalyst, Ni-W catalyst, Ni-Mo catalyst etc.,

The crystalline zeolites thus prepared either alone or in admixture with amorphous SiO ₂ and metallic substances such as Pt, Re, Pd, W, Mo, Ni, Co, V, Cr, Ti, Cu, F, P, B, Ge, TI, Ta, Mg, etc. may be used to treat hydrocarbons or hydrocarbon fractions, in particular for hydrogenation, hydrocracking, dehydrogenation, isomerization, alkylation, hydrogenation refining ^; and Compounds, hydrogenation of olefins, dlolefins and aromatics, dealkylation of alkylaromates, hydration of olefins, etc.

They can also be used for catalytic dewaxing in the manufacture of lubricating oils, in the production of jet-streams with a low freezing point, in the synthesis of alcohols, especially methanol, in petrol and the like.

Example 1

Aluminum hydrate containing 60% Al 2 O 3 was dissolved in 65 g of 40% NaOH in an amount of 28 g. While stirring continuously, this sodium aluminate solution is mixed with 1000 g of an aqueous solution of silica sol containing 30% SiO2 and 0.5% Na2O. A thin slurry of pH = 11 is formed (to which 250 g of dletanolamine 98% w / w dissolved in 1000 ml of water is added. The resulting slurry is poured into a pressure vessel and heated for about 93 h at 195 ° C. After this time, the contents of the reaction mixture in the vessel were cooled, filtered and washed with distilled water, alternately with NH 4 OH and HNO 3, using about 340 liters of water for washing, and the filtered cake was dried at 105 ° C for about 24 hours. There was obtained at least 340 g of a powdered product which, according to X-ray analysis, had a composition of crystalline zeolite of the ZSM-8 type of about 90% and the remainder consisted of amorphous SiO2.

Al 2 O 3, 0.45% Na 2 O, 0.05% K 2 O, loss on ignition at 750 ° C 7.5%.

Example 2

A starting reaction mixture of the same composition as in Example 1 was used except that about 20 g of the crystalline zeolite from the previous experiment was added to the starting slurry prior to heat treatment. Crystals of this ZSM zeolite are seeded from the starting reaction mixture prior to hydrothermal treatment. The temperature is maintained at about 175 ° C for about 95 h with occasional stirring of the reaction mixture. After this time, the obtained product in an amount of about 350 g of ZSM-8 crystalline zeolite powder is washed from alkalis, mixed with about 150 g of 25% silica, dried, tableted and calcined at 600 ° C for about 4 h.

Example 3

About 100 g of crystalline Al2 (SCU3.36H2O) is dissolved in 300 ml H2O and precipitates 1300 g of technical waterglass containing about 30% SiO2, and the resulting suspension has a pH of 11. 250 g of dletanololamium in 500 ml of water are added. After complete homogenization, heat in a pressure vessel at 175 ° C for about 95 h with occasional stirring, then cool, filter, and wash alternately with distilled water, HNO 3 and NH 4 OH The wet, washed cake is dried to give a powdered ZMS. The composition of the product was as follows: 93% O ₂ O ₂ , 2% Al 2 O 3, 0.47% Na ₂ O, 0.05% K ₂ O, loss on ignition at 600 ° C 4.5%.

Claims (2)

SUBJECT A process for the preparation of crystalline zeolites by heat treatment of a mixture comprising SIO2, Al2O3, alkali H2O and amines, characterized in that the reaction mixture of sodium aluminate or inorganic or organic aluminum compound together with silica containing less than 1% Ν · β2θ or sodium water with a molar ratio SiO 2 / Al 2 O 3 in the range of 10 to 200 and a molar ratio of Na 2 O 2 / SiO 2 of 0.01 to 2.0 with the addition of alkylamines or alkanolamines in mol. ratio to SiO2 0.01 to 2.0 At pH = 7 and 12, they undergo coveratalization at a temperature of 90 to 220 ° C and a pressure of 0.1 to 30 MPa for 1 to 100 days, after which the crystalline zeolite formed is dried at a temperature below 1% after alkali washing. 100 to 200 ° C, molds and calcines at 400 to 750 ° C. 2. The process of claim 1 wherein 0.1-20% of the crystalline zeolite produced in the previous batch is added to the initial reaction mixture prior to heat treatment.