阅读说明：本技术 采用火焰喷雾热解制造粉状多孔结晶金属硅酸盐的方法 (Method for preparing powdery porous crystalline metallosilicate by flame spray pyrolysis ) 是由 F·施密特 J·安东 M·帕斯卡利 A·海因罗特 S·威兰 H·莫雷尔 P·克雷斯 M 于 2019-09-16 设计创作，主要内容包括：本发明涉及一种用于制造粉状多孔结晶金属硅酸盐的方法,其包括以下步骤：(a)采用包含以下的含水混合物进行水热合成(A)硅源,(B)金属源,和(C)辅助组分,产生反应产物1的含水悬浮液,所述含水悬浮液包含粗多孔结晶金属硅酸盐；和(b)使反应产物1火焰喷雾热解,其中将在步骤(a)中获得的含水悬浮液喷雾到由在氧气的存在下燃料燃烧产生的火焰中以形成粉状多孔结晶金属硅酸盐；其中在步骤(a)中获得的包含反应产物1的含水悬浮液表现出≤70重量％的固体含量；并且其中在火焰热解期间至少90重量％的多孔结晶金属硅酸盐所经历的有效峰值温度T-(eff)在T-(min)<T-(eff)<T-(max)的范围内,并且其中T-(min)为750℃,并且其中T-(max)为1250℃。(The invention relates to a method for producing a powdery porous crystalline metallosilicate, comprising the following steps: (a) hydrothermally synthesizing (a) a silicon source, (B) a metal source, and (C) an auxiliary component with an aqueous mixture comprising an aqueous suspension of a reaction product 1, said aqueous suspension comprising a crude porous crystalline metallosilicate; and (b) flame spray pyrolysis of the reaction product 1, wherein the aqueous suspension obtained in step (a) is sprayed into a flame resulting from combustion of a fuel in the presence of oxygen to form a powdery porous crystalline metallosilicate; wherein the aqueous suspension obtained in step (a) comprising the reaction product 1 exhibits a solids content of ≤ 70 wt ≤(ii) a And wherein at least 90 wt.% of the porous crystalline metallosilicate experiences an effective peak temperature T during flame pyrolysis eff At T min <T eff <T max And wherein T is min Is 750 ℃ and wherein T max Is 1250 ℃.)

1. a process for the preparation of a powdered porous crystalline metallosilicate comprising the steps of:

(a) hydrothermal synthesis using an aqueous mixture comprising

(A) A silicon source,

(B) a source of metal, and

(C) the auxiliary components are selected from the group consisting of,

producing an aqueous suspension of reaction product 1 comprising a crude porous crystalline metallosilicate; and

(b) flame spray pyrolysis of the reaction product 1, wherein the aqueous suspension obtained in step (a) is sprayed into a flame resulting from the combustion of a fuel in the presence of oxygen to form a powdery porous crystalline metallosilicate;

wherein the aqueous suspension comprising the reaction product 1 obtained in step (a) exhibits a solids content of ≦ 70 wt.%; and is

Wherein at least 90 wt.% of the porous crystalline metallosilicate experiences an effective peak temperature T during flame pyrolysis_effAt T_min<T_eff<T_maxWithin a range of, and

wherein T is_minIs 750 ℃ and

wherein T is_maxIs 1250 ℃ and

wherein the metal source (B) is a titanium (Ti) source, an iron (Fe) source or an aluminum (Al) source, and

wherein the auxiliary component (C) is selected from the group consisting of organic bases, quaternary ammonium hydroxides, and mixtures thereof.

2. The process according to claim 1, wherein component (a) is selected from fumed silica, precipitated silica, silica produced by a sol-gel process and mixtures thereof.

3. The process of any one of claims 1 to 2, wherein in step (a), component (a) and component (B) are combined into a single component and the component is selected from the group consisting of amorphous mixed metal-silicon oxides, amorphous silica doped with metal oxides, amorphous silica impregnated with metals, metal silicates, tetraalkyl orthosilicates doped with metals, and mixtures thereof.

4. A process according to any one of claims 1 to 3, wherein the metal source (B) is a titanium (Ti) source.

5. The process according to any one of claims 1 to 4, wherein auxiliary component (C) is selected from quaternary ammonium hydroxides, diamines, glycols and mixtures thereof.

6. The process according to any one of claims 1 to 5, wherein auxiliary component (C) is selected from tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetrapentylammonium hydroxide, 1, 6-diaminohexane, 1, 2-pentanediol and mixtures thereof.

7. The method of claim 1, wherein

Component (A) is selected from fumed silica, precipitated silica, silica produced by the sol-gel process and mixtures thereof, and wherein

The metal source (B) is a titanium (Ti) source, and wherein

The auxiliary component (C) is selected from the group consisting of organic bases, quaternary ammonium hydroxides and mixtures thereof, and wherein

The porous crystalline metallosilicate has an MFI or MEL type zeolite structure, and wherein

The fuel used for flame spray pyrolysis is hydrogen.

8. The method of claim 1, wherein

Combining component (a) and component (B) as a single component and the component is selected from the group consisting of amorphous mixed metal-silicon oxides, amorphous silica doped with metal oxides, amorphous silica impregnated with metals, metal silicates, tetraalkyl orthosilicates doped with metals, and mixtures thereof, and wherein

The metal source (B) is a titanium (Ti) source, and wherein

The auxiliary component (C) is selected from the group consisting of organic bases, quaternary ammonium hydroxides and mixtures thereof, and wherein

The porous crystalline metallosilicate has an MFI or MEL type zeolite structure, and wherein

The fuel used for flame spray pyrolysis is hydrogen.

9. The method of any one of claims 1 to 8, wherein the auxiliary component is tetrapropylammonium hydroxide.

10. The method of any one of claims 1 to 9, wherein T_minIs 800 ℃ and wherein T_maxIs 1200 ℃.

11. The method of any one of claims 1 to 9, wherein T_minIs 850 ℃ and wherein T_maxThe temperature was 1100 ℃.

12. The process of any one of claims 1 to 11, wherein the aqueous mixture in step (a) further comprises suitable seed crystals.

13. The process as claimed in any one of claims 1 to 6 and 9 to 12, wherein the porous crystalline metallosilicate has an MFI or MEL-type zeolite structure.

14. The process as claimed in any one of claims 1 to 6 and 9 to 13, wherein the porous crystalline metallosilicate has a zeolite structure of the MFI type.

15. The process according to any one of claims 1 to 6 and 9 to 14, wherein auxiliary component (C) is selected from quaternary ammonium hydroxides, diamines, glycols and mixtures thereof, and wherein the metal source (B) is a titanium (Ti) source.

16. The process according to any one of claims 1 to 6 and 9 to 15, wherein auxiliary component (C) is selected from tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetrapentylammonium hydroxide, 1, 6-diaminohexane, 1, 2-pentanediol and mixtures thereof, and wherein metal source (B) is a titanium (Ti) source.

17. The process according to any one of claims 1 to 6 and 9 to 16, wherein auxiliary component (C) is tetrapropylammonium hydroxide, and wherein metal source (B) is a titanium (Ti) source, and wherein the porous crystalline titanium silicate has an MFI-type zeolite structure.

18. The method of any one of claims 1 to 6 and 8 to 17, wherein the fuel for flame spray pyrolysis is hydrogen.

19. The process according to any one of claims 1 to 18, wherein the porous crystalline metallosilicate thus obtained exhibits a loss on ignition of less than 5% by weight in accordance with DIN 18128: 2002-12.

20. A method according to any one of claims 1 to 19, wherein step (b) is followed by a shaping step (c) comprising the sub-steps of:

(1) adding water to obtain an aqueous suspension of powdered porous crystalline metallosilicate,

(2) mixing the suspension obtained in substep (1) with a granulation aid,

(3) compacting, granulating, spray drying, spray granulating and/or extruding the product obtained in sub-step (2) to obtain the porous crystalline metallosilicate in the form of granules, spheres, tablets, solid cylinders, hollow cylinders or honeycombs.

Background

The invention relates to a method for producing a powdery porous crystalline metallosilicate.

The term "silicate" refers to a material consisting of tetrahedral SiO₄The resulting compounds, the tetrahedrons of which may be linked to each other in various ways. Such metal-containing silicate structures are referred to as metal silicates. An important example of a metal silicate is zeolite.

The zeolite being a crystalline silicate, e.g. aluminosilicate, wherein the silicate tetrahedra (SiO)₄ ^-) And other structural elements (e.g., AlO)₄ ^-Tetrahedra) create regular structures that exhibit cavities and pores. There are various typesZeolites, which are named according to their structure type. General information about Zeolites, in particular the crystal structure types of known Zeolites, can be found in "Zeolites" of Ullmann's Encyclopedia of Industrial Chemistry, published on-line at 15.4.2012 (DOI:10.1002/14356007.a 28-475. pub 2).

Due to their unique pore structure, zeolites exhibit interesting properties and can be used, for example, as oxidation catalysts.

Synthetic zeolites can be prepared by hydrothermal synthesis in the presence of a pore structure-forming template. For example CN 101348263 a discloses a process for the preparation of zeolites having Si/Al ratio of 50 to 5000 and particle size of 30 to 200 μm, comprising the following process steps: (1) providing a reaction mixture comprising a silicon source and an aluminum source and a metal hydroxide; (2) carrying out hydrolysis reaction; (3) subsequently spray drying the mixture to form aluminosilicate microspheres; (4) hydrothermal reaction of the previously prepared microspheres in the presence of water and an organic amine at a temperature of 160 to 200 ℃ and crystallization of the zeolite formed; (5) washing; (6) drying; and (7) calcining it at a temperature of from 350 to 800 ℃.

US 4410501 discloses a process for preparing titanium silicalite molecular sieves. The preparation method of the titanium silicalite molecular sieve comprises the following steps: (1) formation of a synthesis gel from a hydrolysable silicon compound (e.g. tetraethyl orthosilicate) and a hydrolysable titanium compound in the presence of tetra-n-propylammonium hydroxide at 175 ℃, (2) subsequent hydrothermal synthesis, hydrolysis and crystallization of the reaction mixture. After the crystallization had ended, the crystals were (3) removed by filtration, (4) washed, (5) dried and finally (6) calcined at 550 ℃ for 6 hours.

EP 814058 a1 discloses the preparation of various zeolites from corresponding high-heat generated mixed metal-silicon oxides. Obtaining a mixed metal-silicon oxide by: (1) hydrothermal synthesis is carried out in the presence of a template selected from the group consisting of amines, ammonium compounds and alkali/alkaline earth metal hydroxides at a temperature between 100 and 220 ℃, followed by (2) filtration, (3) washing with water and (4) calcination, for example at a temperature of 550 ℃ over four hours. In a particular embodiment, a preformed particulate mixed oxide material comprising a template is prepared by spray drying, which is subsequently subjected to hydrothermal synthesis, filtration, washing and calcination.

CN 1482062 discloses a method for preparing titanium silicalite molecular sieve-1, in which solid silica gel is hydrothermally reacted with an inorganic titanium source. The method comprises the following steps: (1) with Ti (SO)₄)₂Impregnating solid silica gel, (2) calcining, (3) reacting silica gel with Ti (SO)₄)₂The synthesis of the catalyst comprises the steps of (1) carrying out hydrothermal synthesis on + TPAOH + water, (4) (precipitation and) filtering, (5) washing, (6) drying and (7) calcining.

The process steps following hydrothermal synthesis in the prior art procedure are both expensive and time consuming. In particular, the washing of organic matter from the crude, porous crystalline metallosilicates deposited during hydrothermal synthesis is cumbersome and generates large amounts of waste water, which often contain substances that are harmful to aquatic organisms and difficult to dispose of, such as tetraalkylammonium salts (formed during precipitation). Furthermore, drying and calcining the washed porous crystalline metallosilicate at the end of the procedure is expensive, requiring a lot of time and energy.

In the context of the present invention, it was found that precipitation, filtration, washing, drying and calcination of the crude porous crystalline metallosilicate obtained from hydrothermal synthesis can be completely avoided if the material is instead subjected to a suitable flame pyrolysis procedure. This has not been disclosed or suggested in the prior art and is particularly surprising in view of the fact that: the ordered porous structure of crystalline metallosilicates is known to be destroyed at high temperatures. For example, titanium silicalite-1 undergoes irreversible structural changes at temperatures above 650 ℃ (see, for example, Advanced Materials Research vol.287-290,2011, p.317-321) that are well beyond the temperatures inside the flame of a flame pyrolysis apparatus and during combustion of the organic residues deposited on the coarse porous crystalline metallosilicate particles during flame pyrolysis.

In the context of the present invention, it was found that flame pyrolysis can be carried out with a crude porous crystalline metallosilicate material obtained from hydrothermal synthesis in such a way that its ordered porous crystalline metallosilicate structure is maintained without adversely affecting its catalytic properties.

Summary of The Invention

In particular, it was found that a powdery porous crystalline metallosilicate can be obtained by a process comprising the steps of:

(a) hydrothermal synthesis is carried out with an aqueous mixture comprising:

(A) a silicon source,

(B) a source of metal, and

(C) the auxiliary components are selected from the group consisting of,

producing an aqueous suspension of reaction product 1 comprising a crude porous crystalline metallosilicate; and

(b) flame spray pyrolysis of the reaction product 1, wherein the aqueous suspension obtained in step (a) is sprayed into a flame resulting from the combustion of a fuel in the presence of oxygen to form a powdery porous crystalline metallosilicate;

wherein the aqueous suspension comprising the reaction product 1 obtained in step (a) exhibits a solids content of ≦ 70 wt.%; and is

Wherein at least 90 wt.% of the porous crystalline metallosilicate experiences an effective peak temperature T during flame pyrolysis_effAt T_min<T_eff<T_maxWithin a range of, and

wherein T is_minIs 750 ℃ and

wherein T is_maxIs 1250 ℃ and

wherein the metal source (B) is a titanium (Ti) source, an iron (Fe) source or an aluminum (Al) source, and

wherein the auxiliary component (C) is selected from the group consisting of organic bases, quaternary ammonium hydroxides, and mixtures thereof.

Hydrothermal synthesis

Hydrothermal synthesis, also known as hydrothermal crystal growth, is a process for crystallization from aqueous mixtures at temperatures in the range of about 100 to about 300 ℃ and high pressures up to about 100 bar, which is useful for reactants and products that are sparingly soluble in aqueous solution below 100 ℃. The hydrothermal synthesis of powdered porous crystalline metallosilicates, in particular zeolites, is well known in the art. Step (a) of the process of the present invention is carried out by conducting the hydrothermal synthesis with an aqueous mixture comprising (a) a silicon source, (B) a metal source, and (C) an auxiliary component, resulting in an aqueous suspension of reaction product 1, said aqueous suspension comprising crude porous crystalline metallosilicate. Preferably, step (a) of the process of the present invention is carried out at a temperature of from 100 to 250 ℃, more preferably from 100 to 200 ℃, under autogenous pressure generated in a pressure-resistant reactor, such as an autoclave. The pressure established during the hydrothermal synthesis in step (a) of the process according to the invention may be in the range of 1.05 to 50 bar. Preferably, the pressure is in the range of 1.5 to 30 bar; more preferably, the pressure is in the range of 2 to 20 bar. In general, the above reaction conditions enable the skilled person to carry out step (a) of the process of the invention in less than 12 hours, preferably in 0.1 to 6 hours, more preferably in 0.5 to 4 hours.

The hydrothermal synthesis is usually carried out in an alkaline medium at a pH above 7. The hydrothermal synthesis according to the invention is preferably carried out at a pH of from 8 to 14, more preferably from 9 to 13. .

Generally, the hydrothermal synthesis of porous crystalline metallosilicates requires the use of auxiliary components to facilitate the dissolution of the silicon source and the metal source, and to adjust the pH to suit the crystal formation. Furthermore, the auxiliary component provides a template which determines the crystal structure of the metal silicate formed by incorporation into the crystal lattice of the product during hydrothermal synthesis. Only auxiliary components which are thermally and/or oxidatively decomposed during flame spray pyrolysis in step (b) are suitable for the process according to the invention. Preferably, in the process of the present invention, the auxiliary component is decomposed to a degree of greater than 70 wt.%, most preferably to a degree of greater than 90 wt.%. The corresponding auxiliary components are well known to the person skilled in the art.

Typical examples of auxiliary components suitable for the process of the invention which can be used to facilitate the dissolution of the silicon source and the metal source and to adjust the pH are inorganic or organic bases such as quaternary ammonium hydroxides, diamines, glycols and mixtures thereof. Typical examples of auxiliary components (templates) suitable for use in the process of the invention which can be used to support the formation of the crystal structure of the metal silicate are quaternary ammonium hydroxides, diamines, glycols and mixtures thereof, more particularly tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetrapentylammonium hydroxide, 1, 6-diaminohexane, 1, 2-pentanediol and mixtures thereof.

In a preferred embodiment, the process according to the invention supports the formation of the crystal structure of the metal silicate with one or more of the following auxiliary components (templates): tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetrapentylammonium hydroxide, 1, 6-diaminohexane, 1, 2-pentanediol, and mixtures thereof.

Particularly preferred processes according to the invention employ tetrapropylammonium hydroxide as auxiliary component. The quaternary ammonium compounds are preferably used in the form of aqueous solutions.

In a preferred embodiment, the process according to the invention uses tetra-n-propylammonium hydroxide (TPAOH) to support the formation of titanium silicalite molecular sieve-1 (MFI structure).

In another preferred embodiment, the process according to the invention uses tetra-n-butylammonium hydroxide to support the formation of titanium silicalite molecular sieve-2 (MEL structure).

It is obvious to the person skilled in the art that the auxiliary components for the hydrothermal synthesis according to the invention have to be selected such that (i) the source of silicon and the source of metal are dissolved, (ii) the pH is adjusted and (iii) the crystal structure of the metal silicate is supported. This may be accomplished by one adjunct component capable of performing all three functions ((i), (ii), and (iii)), or by multiple adjunct components that each perform a portion of a set of functions ((i), (ii), and (iii)).

There is in principle no limitation on the molar ratio of the total amount of auxiliary components (templates) used in step (a) of the process according to the invention for supporting the formation of the crystal structure of the metal silicate to the amount of silicon. Preferably, the molar ratio is selected within the following range: 0.12. ltoreq. mol of template/mol of silicon < 0.20.

For optimal performance of step (a) of the process according to the invention, the aqueous mixture may additionally comprise suitable seed crystals. Suitable seeds and methods for obtaining them are known to the person skilled in the art. In a preferred embodiment, silicalite-1 seeds or titanium silicalite-1 seeds are added to the reaction mixture of step (a) of the process of the invention to support the formation of titanium silicalite-1 crystals (MFI-type structure). In another preferred embodiment, seeds of silicalite-2 or seeds of titanium silicalite-2 are added to the reaction mixture of step (a) of the process of the invention to support the formation of titanium silicalite-2 crystals (MEL-type structure).

The silicon source used in the process according to the invention can in principle be any compound which comprises silicon dioxide or a silicon-containing mixed oxide or which is capable of forming silicon dioxide or a silicon-containing mixed oxide as a result of oxidative or thermal and/or hydrolytic decomposition. However, preference is given to compounds comprising amorphous silica or to mixed oxides containing amorphous silicon, or such compounds can be formed by oxidative or thermal and/or hydrolytic decomposition. The corresponding silicon source may be selected, for example, from fumed silica, precipitated silica, silica produced by a sol-gel process, and mixtures thereof. Preferred processes according to the invention employ a component (a) selected from: fumed silica, precipitated silica, silica produced by a sol-gel process and mixtures thereof

Fumed silica, also known as fumed silica, is prepared by flame hydrolysis or flame oxidation. This involves oxidizing or hydrolyzing the hydrolyzable or oxidizable feedstock, usually in a hydrogen/oxygen flame. Useful starting materials for the pyrolysis process include organic and inorganic materials. Silicon tetrachloride is particularly suitable. The hydrophilic silica thus obtained is amorphous. Fumed silica is generally obtained in aggregated form. By "aggregated" is understood to mean that the primary particles, i.e. the particles produced in the initial stage of the process, form strong interconnections in the subsequent stages of the reaction, eventually producing a three-dimensional network. The primary particles are substantially free of pores and have free hydroxyl groups on their surface. The water content of such fumed silica silicon sources is typically less than 5.0 wt.%.

Precipitated silicas, also referred to as silica gels, on the other hand, are silicas prepared by precipitation processes, for example, resulting from the reaction of water glass (sodium silicate) with an inorganic acid. The water content of such silica gel is generally in the range of 0.5 to 80% by weight, depending on the drying conditions. Drying can be carried out in various ways, for example with or without heated air, for a few seconds (fast drying) to a few hours (slow drying). The dried gel is called xerogel (water content. ltoreq.40 wt.%), the undried gel is called hydrogel (water content >40 wt.%).

The sol-gel process is a process for preparing non-metallic inorganic or hybrid polymeric materials from colloidal dispersions known as sols. The starting material for sol synthesis is usually a metal or silicon alkoxide. Hydrolysis of such raw materials and condensation between the reactive species formed are essential basic reactions in sol-gel processes. Silicon sources particularly suitable for the sol-gel process are tetraalkyl orthosilicates, wherein the alkyl groups are preferably selected from the group consisting of methyl, ethyl, propyl and butyl. The most preferred tetraalkyl orthosilicate is tetraethyl orthosilicate.

The metal source used in the process according to the invention may be any compound comprising a metal oxide or a metal-containing mixed oxide or may form the corresponding metal oxide or mixed oxide as a result of oxidation or thermal and/or hydrolytic decomposition. The metal sources used in the context of the present invention are sources of titanium (Ti), aluminium (Al) and/or iron (Fe), particularly preferably titanium.

The skilled person is free to choose a suitable source of silicon and metal. In principle, the person skilled in the art can choose between the following combinations: (a) the silicon source and the metal source are both in liquid form, (b) the silicon source is in solid form and the metal source is in liquid form, (c) the silicon source and the metal source are combined into a single component. By "liquid form" is meant that the silicon source and/or the metal source are in liquid form or in solution.

The silicon source in solid form may for example be selected from fumed silica, precipitated silica, silica produced by the sol-gel process and mixtures thereof. High purity silica or fumed silica prepared by a precipitation process is preferred.

The high purity silica prepared by the precipitation method is silica prepared by the precipitation method and having the following contents:

less than 1ppm of aluminium

Less than 0.1ppm of boron

Less than 0.3ppm of calcium

Less than 0.6ppm of iron

Less than 0.5ppm of nickel

Less than 0.1ppm of phosphorus

Less than 1ppm of titanium

-less than 0.3ppm of zinc,

wherein the sum of the above elements and sodium and potassium is less than 5 ppm. Such high purity silica may be prepared, for example, by the method disclosed in WO 2010/037702.

The silicon source and the metal source may be combined into a single component in various ways. In the case of silica gel as silicon source, the combination (e.g. impregnation) with the metal source may be carried out on a xerogel or hydrogel. Examples of such combined components are mixed metal-silicon oxides, metal oxide doped silica, metal impregnated silica, metal silicates, metal doped tetraalkyl orthosilicates and mixtures thereof. Such combined components are preferably amorphous. Preferably, such combined components are amorphous silica doped with a metal oxide, amorphous silica impregnated with a metal, or an amorphous mixed metal-silicon oxide.

Except for SiO₂In addition, the "mixed metal-silicon oxide" also comprises one or more metal oxides, preferably selected from Al₂O₃、TiO₂And Fe₂O₃. The mixed metal-silicon oxide can be prepared by any suitable method, such as flame pyrolysis, co-precipitation, sol-gel methods. Mixed metal-silicon oxides have been disclosed, for example, in EP 0814058 and DE 102007049742.

The "silica doped with metal oxide" can be prepared by several methods well known to those skilled in the art, for example by flame pyrolysis or impregnation methods followed by calcination.

The "metal-impregnated silica" may be prepared by several impregnation methods well known to those skilled in the art, for example by the "incipient wetness" method.

In a preferred embodiment of the process according to the invention, in step (a), component (a) and component (B) are combined into a single component and the component is selected from the group consisting of amorphous mixed metal-silicon oxides, amorphous silica doped with metal oxides, amorphous silica impregnated with metals, metal silicates, tetraalkyl orthosilicates doped with metals and mixtures thereof. More preferably, component (a) is an amorphous silica doped with a metal oxide, an amorphous silica impregnated with a metal, or an amorphous mixed metal-silicon oxide.

In another preferred embodiment of the process according to the invention, in step (a), component (a) is in solid form and component (B) is in liquid form. More preferably, in this case, component (a) is selected from fumed silica, precipitated silica, silica produced by the sol-gel process and mixtures thereof. Most preferably, in this case, component (a) is a high purity silica prepared by precipitation of fumed silica.

The aqueous suspension of the reaction product 1 comprising the crude porous crystalline metallosilicate exhibits a solids content of 70% by weight or less. The solids content wFT (wt%) may be determined from the total Mass (MS) of the suspension and the mass of water (MH) in the suspension₂O) calculating to obtain:

wFT＝(MS-MH₂O)/MS*100％。

preferably, the solids content is in the range of 10 to 70 wt.%; more preferably in the range of 10 to 60 wt.%; most preferably in the range of 20 to 50 wt%. During flame spray pyrolysis in step (b) of the process according to the invention, a solids content of more than 70 wt. -% causes technical difficulties, while a solids content of less than 10 wt. -% adversely affects the economic viability of the process as an excessively large amount of water has to be evaporated. The person skilled in the art knows the methods for adjusting the solids content, for example, the reactants can be used in suitable concentrations or the suspension can be diluted.

Flame spray pyrolysis

The term "flame spray pyrolysis" is well known to those skilled in the art and relates to a process for the thermal oxidative conversion of liquid feedstocks finely dispersed in a gas stream by spraying a suspension into a flame produced by the combustion of a fuel in the presence of oxygen. Flame spray pyrolysis is an approved process for the preparation of metal oxides, as described, for example, in WO 2017/001366 a1 and US 2002/0041963 a 1. For example, WO 2017/001366 a1 discloses a method of this type for producing metal oxide powders by flame spray pyrolysis, in which a siloxane-containing aerosol is introduced directly into the flame in a reactor, where it is converted into silicon dioxide.

The flame spray pyrolysis method according to the present invention requires the use of combustible fuels. Examples of such fuels include hydrogen, methane, ethane, propane, butane, wet/dry or synthetic Natural Gas (NG), and mixtures thereof. The fuel is preferably supplied to the reactor in gaseous form. However, if methane, ethane, propane, butane, wet/dry or synthetic Natural Gas (NG) is used as fuel, the transport of the aqueous suspension injected into the flame must be reduced compared to the use of hydrogen as fuel. Therefore, for the flame spray pyrolysis method of the present invention, it is preferable to use hydrogen as a fuel to achieve a uniform flame temperature and a suitable velocity distribution.

The oxygen may be fed to the reactor in the form of any oxygen comprising gas. In the context of the present invention, air is preferably used.

During the performance of step (b), the average residence time of the material of the suspension obtained in step (a) in the reactor may be between 1 millisecond and 100 seconds. Preferably, the average residence time is in the range of 0.1 to 10 seconds; more preferably in the range of 0.5 to 5 seconds. The total volume (Vt, [ m ] of gas fed to the reactor per unit time was used³/s(STP)]) And reactor volume (VR, [ m ]³]) To calculate the above-mentioned average residence time in the reactor(s) ((<t>,[s])：<t>VR/Vt. The average residence time in step (b) of the process according to the invention is chosen such that oxidative decomposition of the organic residue takes place in this step, but the porous structure of the product obtained is not destroyed.

Spraying the aqueous suspension obtained in step (a) of the process according to the invention during carrying out step (b)Mist, i.e. finely dispersed in the surrounding gas, and thus forming an aerosol, i.e. a three-phase solid/liquid/gas mixture consisting of a gas with finely dispersed liquid droplets therein, which in turn comprise solid particles. The gas used for spraying the aqueous suspension may comprise oxygen and/or at least one of the fuels listed above and/or at least one inert gas, for example nitrogen. Preference is given to using N₂、H₂Or air, with air being particularly preferred.

The aerosol formed in step (b) by spraying the aqueous suspension preferably comprises droplets having a number average droplet diameter of no more than 2mm, more preferably no more than 1mm, most preferably no more than 0.5 mm. The number average droplet diameter of the droplets in the aerosol is a function of the size of the equipment used, the corresponding flow rates, the liquid and gas properties, and other parameters, and can be calculated by numerical simulation by one skilled in the art using standard simulation software (e.g., Ansys Fluent). Alternatively, the number average droplet diameter of the aerosol formed in step (b) may be measured directly by means of laser diffraction. The measured droplet size distribution is used to define the median value d50 as the number average droplet diameter, d50 reflecting the droplet size not exceeding 50% of all particles.

The spraying of the aqueous suspension which takes place in step (b) of the process according to the invention can be carried out by means of different apparatuses and instruments which are well known to those skilled in the art. For example, disk atomizers, rotary atomizers, ultrasonic atomizers, single-phase, two-phase or multi-phase nozzles, as well as various injection systems or the like can be used. Preferably, the aqueous suspension in step (b) of the process according to the invention is sprayed into the flame by means of at least one nozzle.

The oxygen required in step (b) of the process according to the invention may be fed to the flame spray pyrolysis reactor at a plurality of locations. For example, the suspension may be sprayed into a first gas stream comprising air, while most of the air (primary air) is supplied to the flame as a secondary gas stream parallel to the flow direction of the suspension, and a third gas stream (secondary air) may be fed tangentially (e.g. perpendicular to the flow direction of the suspension), e.g. to avoid material deposition. It may also be advantageous to supply fuel to the reactor at a plurality of locations, for example to combine the primary stream (primary fuel stream) with the primary gas stream and the secondary stream (secondary fuel stream, external fuel), for example to stabilize the flame.

In the performance of step (b) of the process according to the invention, it is particularly advantageous when the amount of oxygen is in excess compared to the total amount of all combustible components of the reaction mixture. The reaction mixture is understood to mean the suspension converted in step (b) and also the gaseous components used in step (b). The combustible components of the reaction mixture include, for example, the fuel and the template used. The index lambda (lambda) describes the ratio of the amount of oxygen present in the reaction mixture, each in mol/hour, divided by the amount of oxygen required to completely combust all combustible components in the reaction mixture. Preferably, λ is set to a value in the range of 1 to 10; more preferably, it is set to 2 to 6.

The oxygen and fuel used during step (b) of the process of the present invention may be introduced in a preheated form. A suitable temperature range is 50 to 400 ℃. The suspension produced in step (a) of the process according to the invention may also be introduced into a flame preheated to a temperature of from 50 to 300 ℃. More preferably, the suspension obtained from step (a) of the present invention can be used directly after production, i.e. without cooling, for flame spray pyrolysis according to step (b).

The ratio of the total gas volume (in standard cubic meters) used in step (b) to the amount of aqueous suspension (in kg) used is preferably from 0.1 to 100m³(STP)/kg, more preferably 0.5 to 50m³(STP)/kg, most preferably 1 to 10m³(STP)/kg。

The pulverulent porous crystalline metallosilicates obtainable by the process according to the invention preferably have a zeolitic structure. Zeolites are crystalline silicates such as aluminosilicates, in which the silicate tetrahedra (SiO)₄-) and other structural elements (e.g., AlO₄Tetrahedra) via three-dimensional connection of oxygen atoms produces a regular structure with cavities and pores. There are various types of zeolites, which are named according to their structure type. General information on zeolites, in particular known zeolitesThe type of crystal structure of (2) can be found in the chapter "Zeolites" of Ullmann's Encyclopedia of Industrial Chemistry, published on-line at 15.4.2012 (DOI:10.1002/14356007.a 28-475. pub 2).

The pulverulent porous crystalline metallosilicates obtainable by the process according to the invention preferably have a zeolite structure with a crystal structure of the LTA, MFI, FAU, MOR, MEL or MWW type. Most preferably, the powdery porous crystalline metallosilicate obtainable by the process according to the present invention has an MFI or MEL-type zeolite structure. The crystal structure can be determined by structural analysis using X-ray diffraction (XRD). The International Zeolite Association (IZA, www.iza-online.org) lists the structural types of microporous and mesoporous Zeolite materials.

The pulverulent porous crystalline metallosilicates obtainable by the process according to the invention preferably have micropores and mesopores. According to the definition of IUPAC, micropores have a diameter of less than 2nm and mesopores have a diameter of 2 to 50 nm.

The general composition of the powdery porous crystalline metallosilicates is usually

(SiO₂)_1-x(A_mO_n)_x，

A is an element selected from Ti, Al and Fe having a valence of p; m and n are the number of atoms, where m times p equals 2 n; x is a number between 0.0001 and 0.25, preferably between 0.001 and 0.2 and particularly preferably between 0.005 and 0.1. In the case of a plurality of different metals A, x accordingly relates to the sum of all metal oxides. A is preferably selected from titanium (Ti), aluminum (Al), iron (Fe), particularly preferably titanium (Ti).

The pulverulent porous crystalline metallosilicates obtainable by the process of the present invention may preferably be titanium silicates, aluminosilicates or iron silicates. Particular preference is given to titanium silicates, in particular titanium silicalite-1 (MFI structure) and titanium silicalite-2 (MEL structure).

The median particle diameter (d50) of the metal silicate particles in the aqueous dispersion obtained in step (a) of the process according to the invention is preferably less than 500nm and more preferably less than 400 nm. The median particle diameter of the metal silicate particles can be determined, for example, by dynamic laser light scattering (DLS).

The specific surface area of the powdery porous crystalline metallosilicate obtained by the method can be more than or equal to 20m²A/g, preferably from 30 to 800m²A/g, more preferably 50 to 700m²In g, most preferably from 70 to 600m²(ii) in terms of/g. The specific surface area, also referred to as BET surface area for short, is determined by nitrogen adsorption according to the Brunauer-Emmett-Teller method in accordance with DIN 9277: 2014. The cumulative nitrogen pore volume and micropore volume desorbed were calculated from BJH (BARRETT, JOYNER and HALENDA, Journal of the American Chemical Society,73: 373-380, 1951).

As a measure of the proportion of organic substances in the sample, the loss on ignition (in% by weight) is defined in accordance with DIN 18128: 2002-12. The ashing process removes organic components from the sample; for example, the carbon present is oxidized and escapes in the form of carbon dioxide. The loss on ignition according to DIN 18128:2002-12 of the pulverulent, porous, crystalline metallosilicate obtained by the process according to the invention is preferably less than 5% by weight, more preferably less than 3% by weight, most preferably less than 2% by weight.

In a preferred embodiment, the present invention relates to a process wherein the porous crystalline metallosilicate has a zeolite structure of the MFI type.

In another preferred embodiment, the invention relates to a process wherein the auxiliary component (C) is selected from quaternary ammonium hydroxides, diamines, glycols and mixtures thereof, and wherein the metal source (B) is a titanium (Ti) source.

In another preferred embodiment, the present invention relates to a process wherein the auxiliary component (C) is selected from the group consisting of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetrapentylammonium hydroxide, 1, 6-diaminohexane, 1, 2-pentanediol and mixtures thereof, and wherein the metal source (B) is a titanium (Ti) source.

In another preferred embodiment, the invention relates to a process wherein the auxiliary component (C) is tetrapropylammonium hydroxide and wherein the metal source (B) is a titanium (Ti) source and wherein the porous crystalline titanium silicate has an MFI-type zeolite structure.

In another preferred embodiment, the present invention relates to a process wherein

-component (a) is selected from fumed silica, precipitated silica, silica produced by a sol-gel process and mixtures thereof, and wherein

-the metal source (B) is a titanium (Ti) source, and wherein

-the auxiliary component (C) is selected from organic bases, quaternary ammonium hydroxides and mixtures thereof, and wherein

-the porous crystalline metallosilicate has an MFI or MEL type zeolite structure and wherein

The fuel used for flame spray pyrolysis is hydrogen.

In another preferred embodiment, the present invention relates to a process wherein

-combining component (a) and component (B) as a single component and the component is selected from the group consisting of amorphous mixed metal-silicon oxides, amorphous silica doped with metal oxides, amorphous silica impregnated with metals, metal silicates, tetraalkyl orthosilicates doped with metals and mixtures thereof, and wherein

-the metal source (B) is a titanium (Ti) source, and wherein

-the auxiliary component (C) is selected from organic bases, quaternary ammonium hydroxides and mixtures thereof, and wherein

-the porous crystalline metallosilicate has an MFI or MEL type zeolite structure and wherein

The fuel used for flame spray pyrolysis is hydrogen.

Effective peak temperature T_eff

Effective peak temperature T_effIs the highest temperature experienced by the porous crystalline metallosilicate in each droplet obtained in step (b) during flame spray pyrolysis. Effective peak temperature T_effResulting from many variables such as the size of the equipment used, flow rates, liquid and gas properties, etc. It is calculated by standard molecular dynamics calculations (e.g., Ansys Fluent) as described below.

According to the invention, the effective peak temperature T experienced by at least 90% by weight of the porous crystalline metallosilicate during flame pyrolysis is adjusted_effSo thatThe oxidative decomposition of organic matter present in the reaction product 1 is substantially complete (i.e., elimination of organic matter present in the reaction product 1)>70%, preferably>90% organics), but the porous structure of the product is not destroyed.

To achieve this, the effective peak temperature T_effThe following adjustments must be made: t is_min<T_eff<T_maxWherein T is_min750 ℃ and T_max＝1250℃。

In a preferred embodiment, T is_minAnd T_maxIs selected as T_min800 ℃ and T_max＝1200℃。

In other preferred embodiments, T is_minAnd T_maxIs selected as T_min850 ℃ and T_max＝1100℃。

T is calculated by standard molecular dynamics simulation (e.g., Ansys Fluent)_eff：

The simulations described below may be performed using standard simulation software (e.g., Ansys Fluent) to facilitate calculation of the effective temperature experienced by the porous crystalline metallosilicate in each of the plurality of droplets subjected to flame pyrolysis. The maximum temperature obtained for each droplet is the effective peak temperature T experienced by the porous crystalline metallosilicate contained in that droplet_eff. According to the invention, at least 90% by weight of the effective peak temperature T experienced by the porous crystalline metallosilicate during flame pyrolysis_effThe following adjustments must be made: t is_min<T_eff<T_max. For simulation purposes, the water, silicate and organic residue components of the droplets need to be considered.

Continuous (gas) phase:

for simulation purposes, the gas phase was treated as the ideal gas. Calculating the thermal conductivity, viscosity and heat capacity C of a gas mixture by using the mass-weighted mixing law_p. Pure components (e.g., H) can be obtained from a feed database (e.g., from the Ansys Fluent database)₂，H₂O(v)，CO₂，O₂，N₂) The nature of (c). Mass diffusivity of Components in gas phase Using gas dynamics theoryHowever, the required parameters are all available in a publicly available material database (e.g., the Ansys Fluent database). The fuel mass flow rate and the air mass flow rate are used as input variables. To cause turbulence, an achievable k-model is used. The discrete ordinate model is used to simulate the radiation in the gas phase, using angular dispersion such as: theta division: 4; phi division 4; theta Pixels: 1; phi Pixels: 1; wall: is opaque; internal emissivity: 1; heat transfer coefficient to the environment: e.g. 5W/m²K; ambient temperature: for example 300K. And (3) combustion model: finite rate (first order)/vortex dissipation. For example, with H₂As fuel components: h₂+0.5O₂→H₂O; reaction kinetics: arrhenius rates: 9.87e +8, 3.1e +7J/kmol of activation energy, H₂And O₂Has a rate index of 1, H₂The rate index of O is 0. Mixing rate: a is 4 and B is 0.5.

Dispersed (particulate) phase:

species/properties: calculation of particle Density ρ Using the law of mixing of all components_pAnd particles Cp. If activation energy is not available from the database, it can be obtained by fitting the data of a Differential Scanning Calorimetry (DSC) experiment. The heat of reaction H can be calculated using the standard state enthalpy and Cp_reac。

Particle movement:

the droplet trajectories are calculated using the Euler-Lagrange method (a so-called Discrete Phase Model (DPM) (e.g. in Ansys Fluent), which acts as a solver for simulations). The fluid phase can be treated as a continuous phase (continuous) by solving the Navier-Stokes equation, while the dispersed phase is solved by tracking a large number of particles through the computational flow field. The dispersed phase exchanges momentum, mass and energy with the fluid phase. Since the dispersed phase occupies a small volume fraction in this case, the interparticle interactions are negligible.

The trajectory of the discrete phase particle is predicted by integrating the force balance on the particle, and is represented in the lagrangian reference frame. This force balance corresponds to the particle inertia due to the forces acting on the particles and can be expressed as

WhereinIs an additional acceleration (force/unit particle mass) term,is the drag force per unit mass of the particles, and

τ_ris the relaxation time of the particles and is,is the velocity of the fluid phase and,is the particle velocity, μ is the fluid viscosity and d_pIs a particle diameter having a Reynolds number

Inert heating or cooling of the particles:

when the temperature of the liquid drops is lower than the vaporization temperature T_vapOr when the solvent and organic residues of the droplets have been consumed, i.e. the droplets become dry particles, inert heating or cooling is used. In this case, the particle temperature is calculated using the following equation:

m_pmass of ═ particle (kg)

C_pHeat capacity of ═ particles

A_pSurface area of the particles (m)²)

T_∞Local temperature (K) of continuous phase

h-convective heat transfer coefficient

ε_pEmissivity of ═ particle (dimensionless)

Sigma ═ Stefan-Boltzmann constant

θ_RRadiation temperature

In the simulation, the radiation of the particles was neglected in view of the small volume fraction

The heat transfer coefficient h was evaluated using the correlation between Ranz and Marshall:

d_pdiameter of the particles

k_∞Thermal conductivity of continuous phase

Pr-Prandtl value c of the continuous phase_pμ/k_∞。

Heat and mass transfer during vaporization:

when the liquid droplet reaches the vaporization temperature T_vapAt this point, vaporization of the droplets begins and continues until the droplets reach boiling point, or during which time the solvent in the droplets is consumed.

The droplet temperature is updated according to a thermal equilibrium that relates sensible heat changes in the droplets to convective and latent heat transfer between the droplets and the continuous phase:

h_fglatent heat of water (J/kg).

Assuming that the vaporization rate is controlled by gradient diffusion, the flux of the droplet gas into the gas phase is related to the difference in vapor concentration at the droplet surface from the bulk gas:

N_i＝k_c(C_i，s-C_i，∞) Equation 8

N_iMolar flux of steam

k_cMass transfer coefficient (m/s)

C_i，sConcentration of vapor at the surface (kmol/m)³)

C_i，∞Concentration of vapor in the bulk gas (kmol/m)³)。

By assuming the partial pressure of vapor at the interface and the temperature T of the droplets_pSaturated vapor pressure P of_satEqual to evaluate vapor concentration at the droplet surface:

r is the universal gas constant.

From the solution of the transport equation for species i, the vapor concentration in the host gas is known as:

X_isubject molar fraction of species i

p is local absolute pressure (Pa)

T_∞Local bulk temperature in gas (K)

Mass transfer coefficient k_cCalculated from the Sherwood value correlation:

D_i，mdiffusion coefficient of vapor in the body (m)²/s)

Rate of vaporizationThe calculation is as follows:

M_w，isteam molar weight (kg/kmol)

A_pSurface area of the droplet (m)²)。

Heat and mass transfer during boiling:

when the temperature of the liquid drops reaches the boiling point T_bpTaking into account the fact that the temperature of the liquid droplets remains constant during boiling and by taking into account the phase transition from the liquid phase to the gas phase, the boiling rate equation is adopted

If it is notSmall, then

Heat and mass transfer during reaction/combustion:

when all the water evaporates, combustion starts until all the organic residues are consumed or the particles fly out of the calculation domain through the outlet.

The surface reaction consumes the oxidant species in the gas phase; that is, it provides a (negative) source term during calculation of the transport equation for the species. Similarly, surface reactions are a source of species in the gas phase: the products of the heterogeneous surface reactions appear in the gas phase as specific chemical species. The surface reactions also consume or generate energy, the amount of which is determined by the defined heat of reaction.

The thermal equilibrium of the particles during the surface reaction is

In the case of inert heating h is defined. f. of_hFactor (f).

The surface reaction generates only a portion of the energy (1-f)_h) Appearing as a heat source in the gas phase energy equation, the particles directly absorb a part f of the heat_h. For coal combustion, if the coke burn-off product is CO₂Then it is recommended to put f_hSet to 0.3, the same value can be used for the current simulation.

Product forming

The process according to the invention provides a porous crystalline metallosilicate in powder form. For use as a catalyst, the powder can be converted into a suitable form, for example granules, spheres, tablets, solid cylinders, hollow cylinders or honeycombs, by known methods of shaping powder catalysts, for example compaction, granulation, spray drying, spray granulation or extrusion. Thus, in another aspect, the invention comprises a method according to the invention, wherein step (b) is followed by a shaping step (c) comprising the sub-steps of:

(1) adding water to obtain an aqueous suspension of powdered porous crystalline metallosilicate,

(2) mixing the suspension obtained in substep (1) with a granulation aid,

(3) compacting, granulating, spray drying, spray granulating and/or extruding the product obtained in sub-step (2) to obtain the porous crystalline metallosilicate in the form of granules, spheres, tablets, solid cylinders, hollow cylinders or honeycombs.

The particle size of the shaped bodies is preferably in the range from 0.1 to 10 cm.

For mixing and shaping, all known mixing and shaping apparatuses and methods can be used, and all standard granulation auxiliaries can be used. Such molding devices are known, for example, from Ullmann' sder Technischen Chemie[Ullmann's Encyclopedia of Industrial Chemistry]4 th edition, volume 2, page 295 and beyond (1972). Preference is given to using single-screw and twin-screw extruders or extruders. Numerous known geometries can be produced, e.g. solid cylinders, hollow circlesColumns, stars, etc. However, honeycombs may also be produced.

In a preferred embodiment, the process of the invention is used to obtain titanium-containing zeolites of the titanium silicalite-1 and titanium silicalite-2 type, which can be used, for example, as catalysts in oxidation reactions with hydrogen peroxide. More particularly, such titanium-containing zeolites can be used as catalysts for the epoxidation of olefins with aqueous hydrogen peroxide.

Examples

Example 1: preparation of a crude suspension by hydrothermal Synthesis

According to a corresponding method from example 1 of EP 0814058B 1, at 3m³The synthesis of titanium silicalite molecular sieve-1 zeolite (TS-1; MFI structure type) is carried out in a pressure reactor. The silicon source used is amorphous high-purity silicon dioxide (manufacturer: Evonik Resource impact GmbH) and the titanium source used is TiO₂An aqueous solution of titanium-tetrapropylammonium hydroxide (Ti-TPA solution) in an amount of 19.0% by weight. The Ti-TPA solution was prepared as follows:

90.1kg of deionized water, 167.3kg of a 40% aqueous tetrapropylammonium hydroxide solution (manufacturer: Sachem) and 141.6kg of tetraethyl orthotitanate (manufacturer: Connect Chemicals GmbH) were mixed in a closed vessel at 40 ℃ for one hour. The reaction exotherm resulted in a temperature increase of about 25 ℃. The ethanol formed is subsequently distilled off at 80 ℃ at a distillation rate of 30 l/h. The target value of the obtained Ti-TPA solution is TiO₂Is contained in an amount of 19.0% by weight. After cooling, the Ti-TPA solution was used for the TS-1 synthesis.

The pressure reactor was initially charged with 500kg of high purity silica (Evonik Industries), 382kg of 40% aqueous tetrapropylammonium hydroxide solution (manufacturer: Sachem), 193kg of Ti-TPA solution, 10kg of Siamelec-1 seeds and 1800kg of deionized water. The mixture was stirred in a closed pressure reactor at a stirrer speed of 50rpm for 3 hours at 170 ℃. Heating to 170 ℃ for 180 minutes; after cooling for 150 minutes, the synthesis is complete. Stirring was carried out at a speed of 50rpm from the start to the end of the synthesis.

The silicalite-1 seeds were prepared by hydrothermal synthesis in a pressure reactor of 500kg of high purity silica (Evonik Resource Efficiency GmbH), 400kg of 40% aqueous tetrapropylammonium hydroxide solution (manufacturer: Sachem) and 1800kg of deionized water. The mixture was stirred in a closed pressure reactor at 50rpm for 3 hours at 160 ℃. Heating to 160 ℃ for 180 minutes; after cooling for 150 minutes, the synthesis is complete. Stirring was carried out at a speed of 50rpm from the start to the end of the synthesis.

Example 2: conventional after-treatment after hydrothermal synthesis

Acetic acid (60% by weight) was added to the crude suspension described in example 1 until pH 7 and the precipitate formed was filtered on a filter press and washed with distilled water. The obtained solid was dried by spray drying at an inlet temperature of 420 ℃ and an atomizer speed of 1700min^-1(exit temperature 110 ℃ C.). Subsequently, the partially dried powder was calcined in a rotary tube at a temperature not exceeding 650 ℃ for 2 hours. The BET surface area of the product thus obtained is 470m²The loss on ignition (measured at 550 ℃) was 0.65%. XRD analysis (FIG. 1) showed that the obtained product exhibited the crystal structure of titanium silicalite molecular sieve-1 (TS-1) (ICDD reference code: 01-089-8099). The pore volume obtained by pore analysis according to BJH with nitrogen was 0.23 ml/g.

Example 3 (negative example): spray calcination (T) after hydrothermal Synthesis_eff＝650℃)

Use 18m in a pilot plant³Nitrogen gas/hour the crude suspension obtained in example 1 (15 kg/hour) was sprayed through a two-phase nozzle with an internal diameter of 2mm and a gap of 1mm for atomization. 8m for hydrogen/air flame³Hydrogen per hour and 45m³One air operation per hour. The nitrogen gas delivery rate was 18m³Per hour, the secondary air delivery is 25m³In terms of hours. The temperature measured 1.5 meters below the ignition point was adjusted to 400 c by slightly changing the hydrogen flow rate. The adiabatic combustion temperature in the reactor was about 544 ℃. The mean residence time of the particles in the reactor was 1.35 seconds. The exhaust gas comprising the calcined zeolite was conducted through a cooling zone (coolant temperature: 25 ℃) of 100mm in diameter and 6m in length and then collected at a candle filter (filter candle) at a temperature of up to 250 ℃. By passingThe pre-calcined product (4.4 kg/hour) can be collected by sequentially cleaning the candle filter. The product thus obtained showed a loss on ignition (measured at 550 ℃) of 8.6%, clearly indicating that it is not suitable for further processing (shaping), in view of the fact that there is too much organic residue remaining deposited on the surface of the product (loss on ignition clearly exceeds the limit value of 5%). XRD analysis (FIG. 2) showed that the product exhibited the crystal structure of TS-1(ICDD reference code: 01-089-8099).

Simulation details:

input parameters of the gas phase:

atomized air：18Nm³Hour/hour

Primary air：45Nm³Hour/hour

Secondary air：25Nm³Hour/hour

₂H：8Nm³Hour/hour

Turbulence model: can realizeAnd (4) modeling.

Radiation model in gas phase: discrete coordinate model (Discrete coordinate model), in which

Angular discretization：Theta Divisions：4；Phi Divisions 4；Theta Pixels：1；Phi Pixels：1；

Boundary condition of wall: opacity, internal emissivity: 1;

coefficient of heat transfer to the surroundings (outer wall only)：5W/m²/K；Ambient temperature：300K，

And (3) combustion model:finite Rate/vortex dissipation (eddy-dispersion)

H₂+0.5O₂→H₂O

Reaction kinetics:

arrhenius rates: 9.87e +8 for pro-factor, 3.1e +7J/kmol for activation energy, H₂And O₂Has a rate index of 1, H₂Rate of O meansThe number is 0.

Mixing rate: a is 4 and B is 0.5.

Property/property model:

the gas is treated as the ideal gas. Calculating the thermal conductivity, viscosity and heat capacity C of a gas mixture by using the mass-weighted mixing law_p. Pure component (H) can be obtained from the materials database from Ansys Fluent₂，H₂O(v)，CO₂，O₂，N₂) The nature of (c). The mass diffusivity of each component in the gas phase was calculated using gas dynamic theory and the required parameters were all available from the Ansys Fluent database.

Input parameters for the particle phase:

species/properties:calculation of particle Density ρ Using the law of mixing of all components_pAnd particles C_p。

Species 1: h₂O, the initial mass fraction is 60.3 percent,latent heat of water 2263037J/kg, vaporization temperature T_vap284K, boiling point: t is_bp373K, saturated vapor pressure P_sat(T_p): piecewise linear analysis was performed using 32 points from T274K to 647K.

Species 2: TPAOH with an initial mass fraction of 9.7%,

standard state enthalpy H⁰2.12e8J kmol (for calculation of heat of reaction H)_reac)。

Species 3: silicate with an initial mass fraction of 30%,considered inert.

Mass flow of the suspension Initial 15 kg/hour

_pDiameter (d): primary particle size of 22 μm

Particle group: 100 groups (mass flow per group)Is composed ofThere was no significant difference between the 100 and 1000 groups, so 100 groups were used. )

Number of trials:10 times (random tracking using a discrete random walk model, 10 particles per group, due to turbulence effects, total simulation with mass flow rateOf 1000 particles).

Time scale constant: 0.15 (for random tracking).

Kinetics of the reaction：

TPAOH+18.75O₂→14.5H₂O+CO₂+N₂

Arrhenius rates: the pre-factor is equal to 0.2,

activation energy 8e7J/kmol

O₂Rate index of (2): 1.

particle motion was calculated using equations 1-3. The particles undergo inert heating, evaporation, boiling and combustion, the temperature of which is calculated using equations 4-15.

Figure 5 shows particle temperature versus particle residence time for an exemplary 3 of the 1000 (100 sets x 10 trials per set) calculated particle trajectories obtained in example 3.

Example 4: spray calcination (T) after hydrothermal Synthesis_eff＝1000℃)

Use 18m in a pilot plant³Air/hour the crude suspension obtained in example 1 (25 kg/hour) was sprayed through a two-phase nozzle with an internal diameter of 2mm and a gap of 1mmAnd (4) atomizing. Hydrogen/air flame at 8.5m³Hydrogen per hour and 27m³One air operation per hour. The nitrogen gas delivery rate was 18m³Per hour, the secondary air delivery is 25m³In terms of hours. The temperature measured 1.5 meters below the ignition point was adjusted to 700 c by slightly changing the hydrogen flow rate. The adiabatic combustion temperature in the reactor was about 750 ℃. The average residence time of the particles in the reactor was about 1.1 seconds. The exhaust gas comprising the calcined zeolite was conducted through a cooling zone (coolant temperature: 25 ℃) of 100mm in diameter and 6m in length and then collected at a candle filter at a temperature of up to 250 ℃. The pre-calcined product (7.3 kg/hour) can be collected by sequential cleaning of the candle filters. The BET surface area of the product thus obtained is 489m²The loss on ignition (measured at 550 ℃) was 0.3%. XRD analysis (FIG. 3) showed that the product exhibited the crystal structure of TS-1(ICDD reference code: 01-089-8099).

The simulation of the effective particle temperature was performed analogously to example 3.

Figure 6 shows particle temperature versus particle residence time for an exemplary 3 of the 1000 (100 sets x 10 trials per set) calculated particle trajectories obtained in example 4.

Example 5: (negative examples): spray calcination (T) after hydrothermal Synthesis_eff＝1300℃)

Use 18m in a pilot plant³Air/hour the crude suspension described in example 1 (15 kg/hour) was sprayed through a two-phase nozzle with an internal diameter of 2mm and a gap of 1mm for atomization. Hydrogen/air flame at 17.4m³Hydrogen per hour and 40m³One air operation per hour. The nitrogen gas delivery rate was 18m³Per hour, the secondary air delivery is 25m³In terms of hours. The temperature measured 1.5 meters below the ignition point was adjusted to 950 ℃ by slightly changing the hydrogen flow rate. The adiabatic combustion temperature in the reactor was about 980 ℃. The average residence time of the particles in the reactor was about 0.9 seconds. The exhaust gas comprising the calcined zeolite was conducted through a cooling zone (coolant temperature: 25 ℃) of 100mm in diameter and 6m in length and then collected at a candle filter at a temperature of up to 250 ℃. Tong (Chinese character of 'tong')The pre-calcined product (4.4 kg/hour) can be collected by sequential cleaning of the candle filter. The product thus obtained had a BET surface area of 429 m/g and a loss on ignition (measured at 550 ℃) of 0.6%. XRD analysis (FIG. 4) showed some minor signs of structural damage to TS-1(ICDD reference code: 01-089-. BET and XRD showed that the structure was destroyed, resulting in a loss of surface area of about 15% (compared to example 4), and the resulting product was therefore unsuitable for further processing (i.e. shaping) and use in HPPO testing reactions.

The simulation of the effective particle temperature was performed analogously to example 3.

Figure 7 shows particle temperature versus particle residence time for an exemplary 3 of the 1000 (100 sets x 10 trials per set) calculated particle trajectories obtained in example 5.

Example 6: shaping of the Zeolite powder from example 2 (conventional work-Up)

The powder from example 2 (1200g) was mixed with 75g of methylhydroxyethylcellulose (Tylose MH1000), 75g of Licowax C, 1000g of a silica gel solution (Koestrosol 0830 AS) and 350g of deionized water in an Eirich mixer. The obtained material was extruded through a 3.2mm diameter perforated plate using an extruder (HB-Feinmechanik LTW 63). The extrudates were then dried in a drying oven at 80 ℃ for 1 hour and calcined in a muffle furnace at 570 ℃ for 12 hours.

Example 7: shaping of the Zeolite powder from example 4 (flame spray pyrolysis aftertreatment)

The powder from example 4 (1200g) was mixed with 75g of methylhydroxyethylcellulose (Tylose MH1000), 75g of Licowax C, 1000g of a silica gel solution (Koestrosol 0830 AS) and 350g of deionized water in an Eirich mixer. The obtained material was extruded through a 3.2mm diameter perforated plate using an extruder (HB-Feinmechanik LTW 63). The extrudates were then dried in a drying oven at 80 ℃ for 1 hour and calcined in a muffle furnace at 570 ℃ for 12 hours.

Example 8: catalytic test with catalyst from comparative example 6 (conventional work-up)

The epoxidation of propene was carried out with two fixed-bed reactors, each containing 9g of the catalyst from example 6 in the form of extrudates. The reactors were arranged in series (reactor 1 → reactor 2) and operated in upflow mode. A first feed stream (consisting of methanol, hydrogen peroxide (60 wt%) and water) and a second feed stream (consisting of propylene) were both fed to the first reactor at a total flow rate of 20 g/hr. The reaction pressure was maintained at 25 bar by a pressure retaining valve downstream of the second reactor. The reaction mixture leaving the second fixed bed reactor was depressurized to ambient pressure. The resulting vapor phase was analyzed for propylene, propylene oxide and oxygen, and the resulting liquid phase was analyzed for propylene oxide and hydrogen peroxide. After 23 hours of reaction run, the initial selectivity to propylene oxide was 91.1%. After 480 hours, the selectivity to propylene oxide was 97.7%.

Example 9: catalytic test with catalyst from example 7 (flame spray pyrolysis after-treatment)

Epoxidation of propylene was carried out in the same manner as in example 8, except that the catalyst prepared in example 7 was used.

After 25 hours of reaction run, the initial selectivity to propylene oxide was 93.5%. After 480 hours, the selectivity to propylene oxide was 98.6%.

Table 1: comparison of catalytic test reaction results

Comparison of examples 3-5 with example 2 shows that the process according to the invention comprises considerably fewer process steps than the conventional process. Furthermore, the process disclosed herein avoids the problem of disposing of the waste water that is typically produced during filtration and cleaning of the product after hydrothermal synthesis. Surprisingly, the titanium silicalite obtained after flame spray pyrolysis has a porosity comparable to conventionally prepared titanium silicalite.

It is evident from examples 8 and 9 (summarized in table 1) that both the conventionally prepared catalyst (example 6) and the catalyst obtained according to the present invention (example 7) have high activity and selectivity in the epoxidation of propene to Propylene Oxide (PO) after 480 hours of operation. However, the catalysts obtained according to the invention exhibit a selectivity to propylene oxide of even up to 0.9% compared with conventional catalysts, while exhibiting comparable space-time yields. Therefore, the titanium silicalite-1 catalyst obtained according to the invention can significantly improve the product yield of propylene oxide per unit time and reactor volume.

Example 10:

the synthetic variant of example 1 described below was carried out in a 1L laboratory autoclave and was carried out according to example 4 (T)_eff1000 c) to demonstrate that spray pyrolysis under the appropriate conditions can be applied to various synthetic products without destroying the crystal structure.

General description:

the zeolite was prepared according to the following procedure: in a typical experiment, a metal source, a silicon source, co-component water and optionally a seed sol are filled into a stainless steel autoclave (Buchi, V. 1.1 cm)³D8.4 cm, H20.3 cm, electrically heated) and gently mixed.

Alternatively, the silicon source is combined with or impregnated with a metal source prior to synthesis by treating the silica xerogel or hydrogel with a liquid titanium solution such as titanyl sulfate, titanium oxalate, titanium lactate (or other titanium-containing solutions) to produce a metal-impregnated silica, also known as a silica-titania xerogel or a silica-titania hydrogel. In the examples mentioned herein, titanyl sulfate is used for impregnation on silica hydrogel (optionally followed by a drying step to reduce the water content). After combination, the hydrogel may optionally be dried to a xerogel to change the water content of the material. The silica-titania xerogel or hydrogel is added to the autoclave along with the other components.

For the synthesis of titanium silicalite-1 (MFI structure), silicalite-1 or titanium silicalite-1 seeds (or mixtures thereof) may optionally be used. For the synthesis of titanium silicalite-2 (MEL structure), silicalite-2 or titanium silicalite-2 seeds (or mixtures thereof) may optionally be used.

After sealing the autoclave, the mixture was subjected to waterHeat treatment (heating rate 1 Kmin)^-1) And stirred at 250-450 rpm. The autoclave was then run at about 1Kmin^-1Is cooled to room temperature to obtain the resulting aqueous zeolite-containing suspension.

According to example 4 (T)_effThe crude suspension obtained after hydrothermal synthesis was worked up and analyzed at 1000 ℃.

a) Synthesis was carried out by adding 120g of fumed silica powder, 50g of titanium oxalate, 20g of silicon molecular sieve-1 seed crystal (aqueous solution), 100g of tetrapropylammonium hydroxide (40% aqueous solution) and 200g of water in an autoclave to obtain titanium silicon molecular sieve-1 (MFI-type structure). The autoclave was heated to 160 ℃ and stirred for 180 minutes using the general description above, then cooled. The silicon source has a water content of less than 5% by weight. The XRD spectrum shows the peak positions of the titanium silicalite-1.

b) By adding 300g of tetraethyl orthosilicate (II) in an autoclave>99%), 8g tetraethyl orthotitanate (35% TiO)₂) 130g of tetrapropylammonium hydroxide (40% aqueous solution) and 250g of water were synthesized to obtain titanium silicalite molecular sieve-1 (MFI-type structure). The autoclave was heated to 160 ℃ and stirred for 180 minutes using the general description above, then cooled. The XRD spectrum shows the peak positions of the titanium silicalite-1.

c) By adding 250g of silica-Titania hydrogel (TiO) in an autoclave₂2.5 wt%, water content 60-80 wt%), 115g tetrapropylammonium hydroxide (40% aqueous solution), 20g titanium silicalite-1 seed crystal and 250g water were synthesized to obtain titanium silicalite-1 (MFI-type structure). As described above, prior to synthesis, the silicon source (silica hydrogel) was combined with titanyl sulfate (50% aqueous solution) to obtain a silica-titania hydrogel with a water content of 60-80%. The autoclave was heated to 160 ℃ and stirred for 180 minutes following the general description, then cooled. The XRD spectrum shows the peak positions of the titanium silicalite-1.

d) According to example c), but using a silica-titania hydrogel with a water content of 50 to 70% by weight and 300g of water. The XRD spectrum shows the peak positions of the titanium silicalite-1.

e) According to example c), but using a silica-titania hydrogel with a water content of 50 to 60% by weight and 300g of water. The XRD spectrum shows the peak positions of the titanium silicalite-1.

f) According to example c), but using a silica-titania hydrogel with a water content of 30 to 50% by weight and 300g of water. The XRD spectrum shows the peak positions of the titanium silicalite-1.

g) According to example c), but with a water content of 10 to 30% by weight of silica-titania xerogel and 350g of water. The XRD spectrum shows the peak positions of the titanium silicalite-1.

h) According to example c), but using a silica-titania xerogel with a water content of <10 wt.% and 450g of water. The XRD spectrum shows the peak positions of the titanium silicalite-1.

i) The procedure was as in example d), but the autoclave was heated to 180 ℃ and stirred for 60 minutes. The XRD spectrum shows the peak positions of the titanium silicalite-1.

j) The example e) was followed, but the autoclave was heated to 180 ℃ and stirred for 60 minutes. The XRD spectrum shows the peak positions of the titanium silicalite-1.

k) As in example e), but using 100g of tetrapropylammonium hydroxide (35% in water), the XRD spectrum shows the peak positions of the titanium silicalite-1.

l) according to example e) but using 150g of tetrapropylammonium hydroxide (20% in water) the XRD spectrum shows the peak positions of titanium silicalite-1.

m) according to example e), but using 200g of 1, 6-diaminohexane and no tetrapropylammonium hydroxide (40% in water). The XRD spectrum shows the peak positions of the titanium silicalite-1.

n) following example m), but using 100g of 1, 6-diaminohexane and 50g of tetrapropylammonium hydroxide (40% in water), the XRD spectrum shows the peak positions of the titanium silicalite-1.

o) according to example m), but using 200g of 1, 2-pentanediol instead of 1, 6-diaminohexane. The XRD spectrum shows the peak positions of the titanium silicalite-1.

p) according to example n), but 100g of 1, 2-pentanediol are used instead of 1, 6-diaminohexane. The XRD spectrum shows the peak positions of the titanium silicalite-1.

q) according to example n), but using 50g of 1, 2-pentanediol and 50g of 1, 6-diaminohexane and 50g of tetrapropylammonium hydroxide (40% in water). The XRD spectrum shows the peak positions of the titanium silicalite-1.

r) according to example a) but using 200g of 1, 6-diaminohexane and no tetrapropylammonium hydroxide (40% in water). The XRD spectrum shows the peak positions of the titanium silicalite-1.

s) according to example a) but using 200g of 1, 2-pentanediol and no tetrapropylammonium hydroxide (40% in water). The XRD spectrum shows the peak positions of the titanium silicalite-1.

t) according to example e), but using TiO₂A silica-titania hydrogel in an amount of 3.7 wt%. The XRD spectrum shows the peak positions of the titanium silicalite-1.

u) according to example e), but using TiO₂A silica-titania hydrogel in an amount of 3.5 wt%. The XRD spectrum shows the peak positions of the titanium silicalite-1.

v) according to example e), but using TiO₂A silica-titania hydrogel in an amount of 3.1 wt%. The XRD spectrum shows the peak positions of the titanium silicalite-1.

w) according to example e), but using TiO₂A silica-titania hydrogel in an amount of 2.8 wt%. The XRD spectrum shows the peak positions of the titanium silicalite-1.

x) according to example e), but using TiO₂A silica-titania hydrogel in an amount of 2.3 wt%. The XRD spectrum shows the peak positions of the titanium silicalite-1.

y) according to example e), but TiO₂A silica-titania hydrogel in an amount of 1.8 wt%. The XRD spectrum shows the peak positions of the titanium silicalite-1.

z) according to example e), but using TiO₂A silica-titania hydrogel in an amount of 1.5 wt%. The XRD spectrum shows the peak positions of the titanium silicalite-1.

aa) according to example e), but using TiO₂Content (wt.)1.0 wt% silica-titania hydrogel. The XRD spectrum shows the peak positions of the titanium silicalite-1.

bb) according to example e), but using TiO₂A silica-titania hydrogel in an amount of 0.5 wt%. The XRD spectrum shows the peak positions of the titanium silicalite-1.

cc) by adding 250g of silica-Titania hydrogel (TiO) in an autoclave₂2.5% by weight), 115g of tetrapropylammonium hydroxide (40% aqueous solution), 20g of seed crystals of silicalite-2 and 300g of water were synthesized to obtain titanium silicalite-2 (MEL-type structure). The autoclave was heated to 160 ℃ and stirred for 180 minutes using the general description above, then cooled. The water content of the silica-titania precursor is 50-60 wt%. The XRD pattern shows the peak position of titanium silicalite-2 (as in the ICDD database).

dd) was synthesized by adding 250g of silica xerogel, 115g of tetrapropylammonium hydroxide (40% aqueous solution), 20g of seed crystals of silicon molecular sieve-1, 30g of ammonium iron citrate (ammonium ion citrate) and 350g of water in an autoclave to obtain iron silicon molecular sieve-1 (MFI-type structure). The autoclave was heated to 160 ℃ and stirred for 180 minutes according to the general description above, then cooled. The water content of the silica precursor is 20 to 30% by weight. The XRD pattern shows the peak position of the ferrisilicate molecular sieve-1 (as in the ICDD database).

ee) was synthesized by adding 250g of silica xerogel, 115g of tetrapropylammonium hydroxide (40% aqueous solution), 20g of seed crystal of silicon molecular sieve-1, 30g of ferric ammonium citrate, 50g of aluminum nitrate and 350g of water in an autoclave to obtain an aluminum-Iron-silicon molecular sieve-1 (also known as Iron-ZSM-5) (MFI-type structure). The autoclave was heated to 160 ℃ and stirred for 180 minutes according to the general description above, then cooled. The water content of the silica precursor is 20 to 30% by weight. The XRD spectrum shows the peak position of Iron-ZSM-5 (as in the ICDD database).

Crystallographic data (Source: ICDD database) of titanium silicalite molecular sieve-1

Reference code: 01-089-8099

Compound name: silicon titanium oxide

ICSD code: 88413

Reference documents: lamberti, c, Bordiga, s, Zecchina, a, cartai, a, pitch, a.n., ariili, g., Petrini, g., salavagio, m., Marra, g.l., j.final, 183,222, (1999)

List of reflection results: