CN109721068B - Method for producing titanium silicalite molecular sieve, titanium silicalite molecular sieve produced by method and ammoximation reaction method - Google Patents
Method for producing titanium silicalite molecular sieve, titanium silicalite molecular sieve produced by method and ammoximation reaction method Download PDFInfo
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Abstract
The invention discloses a titanium-silicon molecular sieve and a production method thereof, comprising the following steps: sequentially carrying out a first hydrolysis condensation reaction and a second hydrolysis condensation reaction on a template agent, a titanium source, an organic silicon source and water, leading out generated steam and condensing in the reaction process, sealing the reaction kettle and carrying out hydrothermal crystallization when the mass of a condensate is 0.5-0.8 times of the total mass of the organic silicon source to obtain a hydrothermal crystallization mixture; and mixing the hydrothermal crystallization mixture with the supplementary titanium silicalite molecular sieve, and then carrying out spray forming. The invention also discloses an ammoximation reaction method using the titanium silicalite molecular sieve as a catalyst. According to the method disclosed by the invention, the processes of solid-liquid separation and washing are omitted, and the amount of wastewater is greatly reduced; and the mixture obtained by hydrothermal crystallization can be subjected to spray forming without using an additional adhesive, and the obtained titanium silicalite molecular sieve particles have narrow particle size distribution and show stable and uniform catalytic performance.
Description
Technical Field
The invention relates to the technical field of molecular sieve preparation, in particular to a production method of a titanium silicalite molecular sieve, the titanium silicalite molecular sieve produced by the method, and an ammoximation reaction method using the titanium silicalite molecular sieve as a catalyst.
Background
The titanium silicalite TS-1 is a novel titanium silicalite with excellent catalytic selective oxidation performance formed by introducing a transition metal element titanium into a molecular sieve framework with a ZSM-5 structure. TS-1 not only has the catalytic oxidation effect of titanium, but also has the shape-selective effect and excellent stability of ZSM-5 molecular sieve. As the TS-1 molecular sieve can adopt the pollution-free low-concentration hydrogen peroxide as the oxidant in the oxidation reaction of the organic matters, the problems of complex process and environmental pollution in the oxidation process are avoided, and the molecular sieve has the advantages of incomparable energy conservation, economy, environmental friendliness and the like of the traditional oxidation system and has good reaction selectivity, thereby having great industrial application prospect.
The synthesis of TS-1 was first disclosed in 1981 (USP 4410501). The method comprises the steps of firstly synthesizing a reaction mixture containing a silicon source, a titanium source and organic alkali and/or alkaline oxide serving as a template agent, carrying out hydrothermal crystallization on the reaction mixture in a high-pressure kettle at the temperature of 130-200 ℃ for 6-30 days, and then separating, washing, drying and roasting to obtain the product.
Despite intensive research efforts by researchers on the preparation of titanium silicalite molecular sieves, there are still some problems with the preparation of titanium silicalite molecular sieves, and improvements and optimizations to the existing methods of titanium silicalite molecular sieve production are needed.
Disclosure of Invention
The inventor of the invention finds that the existing titanium silicalite molecular sieve production process mainly has the following problems in the practical process:
(1) the titanium silicalite molecular sieve product obtained by the existing method through separation, washing, drying and roasting can generate a large amount of ammonia nitrogen wastewater in the separation and washing processes, the COD value of the ammonia nitrogen wastewater is extremely high, the requirement of emission and/or recycling can be met only after purification treatment is carried out, and the production burden of titanium silicalite molecular sieve manufacturers is increased by the purification treatment of the large amount of ammonia nitrogen wastewater;
(2) the titanium silicalite molecular sieve product obtained by the existing method through separation, washing, drying and roasting has uneven particle size distribution and wider particle size distribution, and the actual operation process finds that the performance of the titanium silicalite molecular sieve product is different among different production batches and even different sampling positions of the same batch, generally speaking, the titanium silicalite molecular sieve has low activity if the crystal grain is large, and increases the separation difficulty if the crystal grain is small, so that the titanium silicalite molecular sieve has obvious difference between the catalytic performance and the application performance and is not easy to coordinate; meanwhile, a large amount of ammonia nitrogen wastewater can be generated in the separation process, the COD value of the ammonia nitrogen wastewater is extremely high, the requirement of discharge and/or recycling can be met only after purification treatment is carried out, and the production burden of titanium silicalite molecular sieve manufacturers is increased by the purification treatment of the large amount of ammonia nitrogen wastewater;
(3) when the titanium-silicon molecular sieve prepared by the existing method is molded, an adhesive or a precursor thereof needs to be additionally introduced, so that the cost of raw materials is increased.
In view of the above problems, the inventors of the present invention have conducted intensive studies and found that: the method is characterized in that vapor generated in the hydrolysis condensation reaction process is led out and condensed, when the amount of formed condensate is controlled within a certain range, the hydrolysis condensation reaction is finished, hydrothermal crystallization is carried out, the mixture obtained by hydrothermal crystallization is mixed with the titanium silicalite molecular sieve for concentration, the mixture can be directly used for spray forming, the particle size distribution width of the titanium silicalite molecular sieve particles obtained by spray forming can be reduced, the catalytic performance and the application performance of the titanium silicalite molecular sieve are more uniform and stable, the solid-liquid separation and washing process is omitted, and the generation of ammonia nitrogen wastewater is avoided. The present invention has been completed based on this finding.
According to a first aspect of the present invention, there is provided a process for producing a titanium silicalite molecular sieve, the process comprising:
(1) carrying out a first hydrolysis condensation reaction on an organic silicon source, a titanium source, a template agent and water to obtain a first hydrolysis condensation mixture, and carrying out a second hydrolysis condensation reaction on the first hydrolysis condensation mixture to obtain a second hydrolysis condensation mixture;
(2) carrying out hydrothermal crystallization on the obtained second hydrolysis condensation mixture to obtain a hydrothermal crystallization mixture;
(3) mixing the hydrothermal crystallization mixture with a supplementary titanium silicalite molecular sieve to obtain slurry, and carrying out spray forming on the slurry;
and in the first hydrolysis condensation reaction and the second hydrolysis condensation reaction, leading out the generated steam and condensing to obtain condensate, sealing the reaction kettle and adjusting the conditions in the reaction kettle to hydrothermal crystallization conditions for hydrothermal crystallization when the mass of the condensate is 0.5-0.8 times of the total mass of the organic silicon source.
According to a second aspect of the invention, there is provided a titanium silicalite molecular sieve produced by the process of the first aspect of the invention.
According to a third aspect of the present invention, there is provided a cyclohexanone ammoximation reaction method, which comprises contacting cyclohexanone, ammonia and hydrogen peroxide with a titanium silicalite molecular sieve under ammoximation reaction conditions, wherein the titanium silicalite molecular sieve is the titanium silicalite molecular sieve of the second aspect of the present invention.
The titanium silicalite molecular sieve produced by the method can omit the processes of solid-liquid separation and washing of the mixture obtained by hydrothermal crystallization on one hand, and greatly reduce the amount of wastewater generated in the production process; on the other hand, the mixture obtained by hydrothermal crystallization can be directly used for spray forming after adding titanium silicalite molecular sieve for concentration without adopting additional adhesives or precursors thereof, the obtained titanium silicalite molecular sieve particles have narrow particle size distribution, and show stable and uniform catalytic performance when used as a catalyst, and particularly can obtain higher catalytic activity and selectivity when used as a catalyst for ammoximation reaction.
Detailed Description
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
According to a first aspect of the present invention, there is provided a process for producing a titanium silicalite molecular sieve, the process comprising:
(1) carrying out a first hydrolysis condensation reaction on an organic silicon source, a titanium source, a template agent and water to obtain a first hydrolysis condensation mixture, and carrying out a second hydrolysis condensation reaction on the first hydrolysis condensation mixture to obtain a second hydrolysis condensation mixture;
(2) carrying out hydrothermal crystallization on the obtained second hydrolysis condensation mixture to obtain a hydrothermal crystallization mixture;
(3) and mixing the hydrothermal crystallization mixture with the supplementary titanium silicalite molecular sieve to obtain slurry, and carrying out spray forming on the slurry.
The organic silicon source may be any of various materials capable of forming silica under hydrolytic condensation conditions, and may be, for example, one or more selected from silicon-containing compounds represented by formula I,
in the formula I, R 1 、R 2 、R 3 And R 4 Each is C 1 -C 4 Alkyl group of (1). Said C is 1 -C 4 Alkyl of (2) includes C 1 -C 4 Straight chain alkyl of (2) and C 3 -C 4 Specific examples thereof may include, but are not limited to: methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl and tert-butyl.
Preferably, the silicon source is one or more than two selected from methyl orthosilicate, ethyl orthosilicate, n-propyl orthosilicate, isopropyl orthosilicate and n-butyl orthosilicate.
The titanium source can be a titanium source commonly used in the technical field of molecular sieve preparation. In particular, the titanium source may be an organic titanium source (e.g. an organic titanate) and/or an inorganic titanium source (e.g. an inorganic titanium salt). The inorganic titanium source may be TiCl 4 、Ti(SO 4 ) 2 、TiOCl 2 One or more of titanium hydroxide, titanium oxide, titanium nitrate and titanium phosphate. The organic titanium source can be one or more than two of fatty titanium alkoxide and organic titanate. The titanium source is preferably an organic titanium source, more preferably an organic titanate, and still more preferably of the formula M 4 TiO 4 The organic titanate shown, wherein 4M can be same or different, and each is preferably C 1 -C 4 Alkyl group of (1). The titanium source is particularly preferably one or two or more of tetraisopropyl titanate, tetra-n-propyl titanate, tetrabutyl titanate, and tetraethyl titanate.
The template agent can be a template agent commonly used in the technical field of molecular sieve preparation, and specifically can be one or more than two of urea, amine, alcohol amine and quaternary ammonium hydroxide.
The quaternary ammonium base may be various organic quaternary ammonium bases, the amine may be an organic compound having at least one amino group in a molecular structure, and the alcohol amine may be an organic compound having at least one amino group and at least one hydroxyl group in a molecular structure.
Specifically, the quaternary ammonium base can be a quaternary ammonium base shown in a formula II,
in the formula II, R 5 、R 6 、R 7 And R 8 Are the same or different and are each C 1 -C 4 Alkyl of (2) including C 1 -C 4 Straight chain alkyl of (2) and C 3 -C 4 Branched alkyl groups of (a), for example: r 5 、R 6 、R 7 And R 8 Each may be methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl or tert-butyl.
The amine may be an aliphatic amine of formula III,
R 9 (NH 2 ) n (formula III)
In the formula III, n is an integer of 1 or 2. When n is 1, R 9 Is C 1 -C 6 Alkyl of (2) including C 1 -C 6 Straight chain alkyl of (2) and C 3 -C 6 Such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, neopentyl, isopentyl, tert-pentyl and n-hexyl. When n is 2, R 9 Is C 1 -C 6 Alkylene of (2) including C 1 -C 6 Linear alkylene of (A) and (C) 3 -C 6 Such as methylene, ethylene, n-propylene, n-butylene, n-pentylene or n-hexylene.
The alcohol amine may be an aliphatic alcohol amine represented by formula IV,
(HOR 10 ) m NH (3-m) (formula IV)
In the formula IV, m are R 10 Identical or different, are each C 1 -C 4 Alkylene of (2) including C 1 -C 4 Linear alkylene of (A) and (C) 3 -C 4 Branched alkylene groups of (a), such as methylene, ethylene, n-propylene and n-butylene; m is 1, 2 or 3. Preferably, the alcohol amine is one or more than two of monoethanolamine, diethanolamine and triethanolamine.
Specific examples of the templating agent may include, but are not limited to, one or more of urea, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetrapentylammonium hydroxide, ethylamine, n-butylamine, butanediamine, hexamethylenediamine, monoethanolamine, diethanolamine, and triethanolamine.
Preferably, the templating agent is a quaternary ammonium base, more preferably tetraethylammonium hydroxide and/or tetrapropylammonium hydroxide.
According to the method of the present invention, in step (1), the amounts of the organic silicon source, the titanium source, the template and water can be selected conventionally. Generally, the molar ratio of the organic silicon source, the titanium source, the templating agent, and the water may be 100: (0.005-10): (0.005-40): (200-10000), preferably 100: (0.05-8): (0.5-30): (500- & ltSUB & gt 5000- & gt), more preferably 100: (0.2-8): (5-25): (800-4000), more preferably 100: (1-6): (10-20): (1200-3000), the organic silicon source is SiO 2 The titanium source is calculated as TiO 2 In terms of NH, the template agent 3 And (6) counting.
In the step (1), an organic silicon source, a titanium source, a template and water may be simultaneously added to the reaction kettle to perform a first hydrolysis condensation reaction, or the template and water may be prepared into an aqueous solution containing the template, the titanium source and the organic silicon source are prepared into a mixture containing the titanium source and the organic silicon source, and the aqueous solution containing the template and the mixture containing the titanium source and the organic silicon source are simultaneously added to the reaction kettle to perform the first hydrolysis condensation reaction.
The mixture containing the titanium source and the organic silicon source can be obtained by mixing the titanium source and the organic silicon source. Preferably, the mixture containing the titanium source and the organic silicon source can be obtained by a method comprising the following steps: the titanium source and the organic silicon source are mixed with stirring at 0 to 60 ℃, preferably 15 to 40 ℃, more preferably 20 to 30 ℃ for 1 to 2 hours.
The aqueous solution containing the templating agent may be obtained by dispersing the templating agent in water, the mixing may be performed at a temperature of 20-60 deg.C, preferably 15-40 deg.C, more preferably 20-30 deg.C, the mixing may be continued for 1-2 hours, and the templating agent may be provided in pure form or in the form of a concentrated solution.
The first hydrolytic condensation reaction may be carried out at a temperature of 35 to 80 c, preferably 40 to 60 c. Generally, the duration of the first hydrolytic condensation reaction may be from 1 to 20 hours, preferably from 5 to 18 hours, more preferably from 10 to 15 hours.
In the step (1), the first hydrolytic condensation reaction may be carried out under normal pressure (i.e., 1 atm), or may be carried out under pressure. Generally, the first hydrolytic condensation reaction may be carried out at a pressure of from-0.2 MPa to 0MPa, the pressure being a gauge pressure.
The second hydrolytic condensation reaction may be carried out at a temperature of 70 to 98 deg.C, preferably 80 to 96 deg.C, more preferably 90 to 95 deg.C. The duration of the second hydrolytic condensation reaction may be from 1 to 15 hours, preferably from 3 to 12 hours, more preferably from 6 to 10 hours.
In the step (1), the second hydrolytic condensation reaction may be performed under normal pressure (i.e., 1 atm), or may be performed under reduced pressure. Generally, the second hydrolytic condensation reaction may be carried out at a pressure of-0.2 MPa to 0MPa, the pressure being a gauge pressure.
In the step (1), in the hydrolysis condensation reaction process, the titanium source and the organic silicon source undergo hydrolysis condensation reaction, and simultaneously release a small molecular compound, usually alcohol. These small molecule compounds volatilize to form vapor which escapes from the reaction system. According to the method of the invention, the escaping vapour is condensed and the condensate is collected.
According to the method, when the mass of the condensate is 0.5-0.8 time, preferably 0.55-0.75 time of the total mass of the organic silicon source, the reaction kettle is sealed, the conditions in the reaction kettle are adjusted to hydrothermal crystallization conditions, and hydrothermal crystallization is carried out.
When the titanium silicalite molecular sieve is prepared by adopting the existing method, the template agent is easy to decompose in the hydrothermal crystallization process, the quality of the titanium silicalite molecular sieve is influenced, the template agent is a raw material with higher value in the production process of the titanium silicalite molecular sieve, the template agent is difficult to recycle due to ineffective decomposition, and the feeding amount of the template agent is required to be increased for ensuring the quality of the molecular sieve, so that the production cost of the titanium silicalite molecular sieve is obviously increased; in addition, the decomposed template agent forms an oil phase, which not only influences the crystallization of the molecular sieve, but also floats on the upper layer of the hydrothermal crystallization slurry after standing, and partial oil phase substances are attached to the inner surface of the reaction kettle, so that the reaction kettle is polluted, and the cleaning difficulty of the reaction kettle is increased. The inventor of the present invention found in the research process that if the second hydrolytic condensation mixture is mixed with at least part of the condensate liquid and then is subjected to hydrothermal crystallization, the decomposition of the template agent in the hydrothermal crystallization process can be effectively inhibited.
Thus, according to the process of the present invention, in a preferred embodiment, it is preferred to further comprise mixing at least part of the condensate with said second hydrolytic condensation mixture before sealing the reaction vessel.
According to this preferred embodiment, the condensate contains water and alcohol, the alcohol may be present in an amount of 80 to 96 wt.%, preferably 83 to 95 wt.%, more preferably 88 to 92 wt.%, and the water may be present in an amount of 4 to 20 wt.%, preferably 5 to 17 wt.%, more preferably 8 to 12 wt.%, based on the total amount of the condensate. In addition to water and alcohol, the condensate also contains nitrogen, which is typically derived from the templating agent. The concentration of nitrogen element in the condensate may be 0.01 to 50mmol/L, preferably 0.02 to 20mmol/L, more preferably 0.04 to 5mmol/L, and still more preferably 0.05 to 3 mmol/L. Particularly preferably, the concentration of nitrogen element in the condensate is 0.5-1.5mmol/L, so that the decomposition of the template agent in the hydrothermal crystallization process can be better inhibited.
According to this preferred embodiment, the entire condensate can be mixed with the second hydrolytic condensation mixture, or part of the condensate can be mixed with the second hydrolytic condensation mixture. Preferably, the condensate may be used in an amount of 1 to 50 parts by weight, preferably 2 to 40 parts by weight, relative to 100 parts by weight of the second hydrolytic condensation mixture. More preferably, the condensate is used in an amount of 5 to 30 parts by weight with respect to 100 parts by weight of the second hydrolytic condensation mixture. Further preferably, the condensate is used in an amount of 10 to 25 parts by weight with respect to 100 parts by weight of the second hydrolytic condensation mixture, so that the decomposition of the template agent during hydrothermal crystallization can be inhibited and the quality of the molecular sieve obtained by hydrothermal crystallization can be further improved.
According to this preferred embodiment, the second hydrolytic condensation mixture can be mixed with the condensate at a temperature of 20 to 80 ℃, preferably 40 to 60 ℃, for 1 to 6 hours, preferably 1 to 3 hours. The mixing may be carried out by means of stirring.
According to this preferred embodiment, at least part of the condensate may be mixed with the second hydrolytic condensation mixture when the mass of the condensate is 0.5 to 0.8 times, preferably 0.55 to 0.75 times, the total mass of the organic silicon source, and then the reaction vessel may be sealed for hydrothermal crystallization.
In the step (2), the hydrothermal crystallization may be performed under conventional conditions. According to the method of the present invention, a titanium silicalite molecular sieve having a desired crystal form can be obtained even if hydrothermal crystallization is performed at a lower temperature for a shorter time than existing hydrothermal crystallization conditions under the same remaining conditions. According to the method of the present invention, in the step (2), the hydrothermal crystallization is preferably performed at a temperature of 120-. The duration of the hydrothermal crystallization is preferably 6 to 30 hours, more preferably 9 to 25 hours. The hydrothermal crystallization is usually carried out under autogenous pressure, and pressure may be additionally applied during the hydrothermal crystallization. Preferably, the hydrothermal crystallization is performed under autogenous pressure. The hydrothermal crystallization can be carried out in a conventional reaction vessel.
In the step (3), the added complementary titanium silicalite molecular sieve can be a titanium silicalite molecular sieve with a topology structure consistent with that of the titanium silicalite molecular sieve prepared in the step (1) and the step (2), or a titanium silicalite molecular sieve with a topology structure different from that of the titanium silicalite molecular sieve prepared in the step (1) and the step (2). Preferably, the topology structure of the titanium silicalite molecular sieve prepared by the step (1) and the step (2) is consistent with that of the complementary titanium silicalite molecular sieve, and more preferably, the topology structure of the titanium silicalite molecular sieve prepared by the step (1) and the step (2) and that of the complementary titanium silicalite molecular sieve are both titanium silicalite molecular sieves with MFI structures, such as titanium silicalite TS-1.
In the step (3), the weight ratio of the supplementary titanium silicalite molecular sieve to the hydrothermal crystallization mixture is preferably 0.01-10: 1, more preferably 0.05 to 8: 1. further preferably, the weight ratio of the supplementary titanium silicalite molecular sieve to the hydrothermal crystallization mixture is 0.2-5: 1. still more preferably, the weight ratio of the supplementary titanium silicalite molecular sieve to the hydrothermal crystallization mixture is 0.4-3.5: 1, the particle size distribution of the finally prepared titanium silicalite molecular sieve particles can be further improved, and titanium silicalite molecular sieve particles with narrower particle size distribution can be obtained. The hydrothermal crystallization mixture is on a dry basis. In the present invention, the dry basis means the mass of the hydrothermal crystallization mixture after drying at 120 ℃ for 8 hours.
In the step (3), the hydrothermal crystallization mixture and the complementary titanium silicalite molecular sieve can be uniformly mixed by adopting a conventional method. For example, the hydrothermal crystallization mixture and the complementary titanium silicalite molecular sieve can be uniformly mixed by stirring.
In the step (3), the conditions for mixing the hydrothermal crystallization mixture and the complementary titanium silicalite molecular sieve are not particularly limited, and may be performed under conventional conditions. For example, the hydrothermal crystallization mixture may be mixed with the supplemental titanium silicalite molecular sieves uniformly at a temperature of 20 to 100 ℃, preferably 30 to 60 ℃, more preferably 30 to 40 ℃. The mixing duration is based on the capability of uniformly mixing the hydrothermal crystallization mixture and the supplementary titanium silicalite molecular sieve. Generally, the duration of the mixing may be from 0.1 to 12 hours, preferably from 0.5 to 6 hours, more preferably from 1 to 3 hours.
According to the method of the present invention, in the step (4), the conditions for spray forming may be conventionally selected, and the present invention is not particularly limited thereto. Generally, the inlet temperature for spray forming may be 200-450 deg.C, preferably 250-400 deg.C.
According to the method of the present invention, the molecular sieve particles obtained by spray forming can be used directly, for example, as a catalyst; the catalyst may be used after calcination, for example, as a catalyst after calcination. The conditions for the calcination in the present invention are not particularly limited, and the calcination may be carried out under conventional conditions. Specifically, the calcination may be carried out at a temperature of 300-800 ℃, preferably at a temperature of 450-650 ℃, more preferably at a temperature of 500-600 ℃. The duration of the calcination may be from 2 to 12 hours, preferably from 2 to 6 hours. The calcination may be performed in an air atmosphere or an inert atmosphere.
According to a second aspect of the invention, there is provided a titanium silicalite molecular sieve produced by the process of the first aspect of the invention.
The titanium silicalite molecular sieve prepared by the method of the first aspect of the invention has a relatively uniform particle size distribution. The titanium silicalite molecular sieve prepared by the process of the first aspect of the invention is not sieved and has a particle size generally in the range of 20 to 80 microns, wherein the proportion of particles having a particle size in the range of 30 to 50 microns is up to 80% or more, preferably up to 90% or more, such as up to 95%. The particle size of the titanium silicalite molecular sieve is measured by an optical microscope, specifically, the particle size of all particles appearing in an ocular lens range is measured, and the ratio of the number of particles with the particle size within the range of 30-50 micrometers to the total number of the particles is calculated.
The titanium silicalite molecular sieve prepared by the method of the first aspect of the invention has uniform particle size distribution and uniform and stable catalytic performance, and shows improved catalytic activity and selectivity when used as a catalyst for reaction.
According to a third aspect of the present invention, there is provided an ammoximation reaction method, comprising contacting cyclohexanone, ammonia and hydrogen peroxide with a titanium silicalite molecular sieve under ammoximation reaction conditions, wherein the titanium silicalite molecular sieve is the titanium silicalite molecular sieve of the second aspect of the present invention.
According to the ammoximation reaction method of the present invention, the ammoximation reaction conditions are not particularly limited, and may be carried out under conventional conditions.
In general, the molar ratio of cyclohexanone, ammonia and hydrogen peroxide may be 1: 0.2-5: 0.5-2, preferably 1: 1-3: 0.8-1.5.
The contacting may be carried out in a solvent or in the absence of a solvent. The solvent may be one or more of alcohol, nitrile, ether, ester and water. Specific examples of the solvent may include, but are not limited to, one or more of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, t-butanol, methyl t-butyl ether, acetonitrile, and water. Preferably, the solvent is tert-butanol. The amount of the solvent used in the present invention is not particularly limited, and may be selected conventionally. Generally, the solvent may be used in an amount of 10 to 5000 parts by weight, preferably 100-4000 parts by weight, more preferably 1000-3000 parts by weight, relative to 100 parts by weight of cyclohexanone.
According to the cyclohexanone ammoximation reaction process of the present invention, the contact of cyclohexanone, ammonia and hydrogen peroxide may be carried out at a temperature of 40 to 100 deg.C, preferably 60 to 95 deg.C, more preferably 70 to 90 deg.C. The contacting can be carried out in a fixed bed reactor or in a slurry bed reactor. When the cyclohexanone is contacted in a fixed bed reactor, the liquid hourly volume space velocity of the cyclohexanone can be 0.1-50h -1 Preferably 0.2 to 25h -1 More preferably 1-20h -1 More preferably 2 to 15 hours -1 . When the slurry bed reactor is used for contact, the weight ratio of cyclohexanone to titanium silicalite molecular sieve can be 100: 1-50, preferably 100: 2-20.
The present invention will be described in detail with reference to examples, but the scope of the present invention is not limited thereto.
In the following production examples and production comparative examples, X-ray diffraction analysis (XRD) was carried out on a Siemens D5005 type X-ray diffractometer.
In the following preparation examples and comparative preparations, infrared spectroscopic analysis was performed on a Nicolet 8210 type Fourier infrared spectrometer.
In the following preparation examples and preparation comparative examples, the molar composition of the molecular sieve was measured on an X-ray fluorescence spectrometer of model 3271E, manufactured by Nippon chemical mechanical Co., Ltd.
In the following preparation examples and comparative preparations, the particle size of the titanium silicalite particles was measured using an optical microscope, specifically, the particle size of all particles present in the ocular range was measured, and the ratio of the number of particles having a particle size in the range of 30 to 50 μm to the total number of particles was calculated.
In the following preparation examples and preparation comparative examples, the total specific surface area and pore volume were measured by the BET method.
In the following production examples and production comparative examples, the radial crush strength was measured by the method specified in RIPP 25-90.
In the following preparation examples and comparative preparations, the decomposition rate of the template agent in the hydrothermal crystallization process was calculated by the following method:
the decomposition rate (%) of the template (1-the weight of the oil phase separated after hydrothermal crystallization/the total weight of the template added before crystallization) × 100%, wherein the weight of the oil phase separated after hydrothermal crystallization and the total weight of the template added before crystallization are both calculated as N element.
In the following experimental examples and experimental comparative examples, the content of each component in the obtained reaction solution was analyzed by gas chromatography, and on the basis, the conversion of cyclohexanone and the selectivity of caprolactam were calculated by the following formulas, respectively:
cyclohexanone conversion (%) × 100 [ (% by mole of added cyclohexanone-by mole of unreacted cyclohexanone)/mole of added cyclohexanone ];
caprolactam selectivity (%) × 100% in terms of molar amount of caprolactam produced by the reaction/(molar amount of cyclohexanone added-molar amount of unreacted cyclohexanone).
Preparative examples 1-10 are illustrative of the titanium silicalite molecular sieves of the present invention and methods for their production.
Reference example 1
This reference is made to the preparation of molecular sieves TS-1 by the methods described in Zeolite, 1992, Vol.12, pp.943-950, which is used to illustrate the synthesis of titanium silicalite TS-1 by conventional hydrothermal crystallization.
At room temperature (20 ℃), 22.5 g of tetraethyl orthosilicate (silicon ester 28, available from sierra katt chemical trade ltd, zhang) was mixed with 7.0 g of tetrapropylammonium hydroxide, 59.8 g of distilled water was added, and after mixing and stirring, hydrolysis was carried out at 60 ℃ for 1.0 hour under normal pressure to obtain a hydrolysis solution of tetraethyl orthosilicate, a solution consisting of 1.1 g of tetrabutyl titanate and 5.0 g of anhydrous isopropyl alcohol was slowly added under vigorous stirring, and the resulting mixture was stirred at 75 ℃ for 3 hours to obtain a clear and transparent colloid. Placing the colloid in a stainless steel sealed reaction kettle, and standing at a constant temperature of 170 ℃ for 3 days to obtain a mixture of crystallized products; the mixture was filtered, washed with water, and dried at 110 ℃ for 60 minutes to obtain a molecular sieve raw powder. The molecular sieve raw powder is roasted for 3 hours at the temperature of 550 ℃ in the air atmosphere to obtain the molecular sieve.
Through detection, in an XRD spectrogram of the obtained molecular sieve, a five-finger diffraction characteristic peak which is specific to an MFI structure exists between 22.5-25.0 degrees of 2 theta, and the molecular sieve is shown to have the MFI structure similar to TS-1. Fourier infrared spectrum at 960cm -1 The characteristic absorption peak which the all-silicon molecular sieve does not have appears in the vicinity, and the titanium enters the sample framework. The above characterization results show that the prepared molecular sieve is a titanium silicalite TS-1. The molecular sieve property parameters are listed in table 4.
Preparation of example 1
(1) A50 wt% concentrated solution of tetrapropylammonium hydroxide (the solvent for this concentrated solution is water) was added to deionized water at 20 ℃ under 1 atm with stirring, and mixed for 1 hour to obtain an aqueous solution containing a template.
Tetrabutyl titanate as a titanium source and ethyl orthosilicate (silicon ester 28, same as in reference example 1) as an organic silicon source were mixed at 20 ℃ and 1 atm with stirring for 1 hour to obtain a mixture containing the titanium source and the organic silicon source.
Feeding an aqueous solution containing a template agent and a mixture containing a titanium source and an organic silicon source into a reaction kettle according to the proportion listed in table 1, and carrying out a first hydrolytic condensation reaction and a second hydrolytic condensation reaction in sequence with stirring according to the reaction conditions listed in table 1 to obtain a hydrolytic condensation mixture, wherein the mass ratio of a condensate determining the end point of the second hydrolytic condensation reaction to the total amount of the organic silicon source is listed in table 1.
In the hydrolysis condensation reaction process, nitrogen is used for auxiliary purging, steam in the reaction kettle is taken out, the taken steam is condensed by adopting condensed water, the condensate enters a condensate storage tank, and the composition of the condensate is listed in table 2.
(2) After the hydrolysis condensation reaction is completed, the condensate collected in the step (1) is added into the reaction kettle and stirred for 3 hours at the temperature of 40 ℃. The amounts of condensate used relative to 100 parts by weight of the hydrolytic condensation mixture (on a dry basis) are listed in Table 3.
Next, the reaction vessel was sealed, the temperature in the reaction vessel was raised to the hydrothermal crystallization temperature, and hydrothermal crystallization was carried out under autogenous pressure, and the conditions of hydrothermal crystallization and the decomposition rate of the template agent during hydrothermal crystallization are shown in table 3.
After the hydrothermal crystallization is finished, after the temperature in the reaction kettle naturally drops to 30 ℃, the reaction kettle is opened, the titanium silicalite TS-1 (prepared by the same method as in reference example 1) is added into the reaction kettle, and after stirring for 2 hours, the obtained slurry is output. The addition amount of the titanium silicalite TS-1 is shown in Table 3.
(3) The resulting slurry was spray-formed and the resulting particles were calcined at 580 c for 2 hours in an air atmosphere to give molecular sieve particles, the spray-forming conditions being listed in table 3.
Through detection, in an XRD spectrogram of the obtained molecular sieve, a five-finger diffraction characteristic peak which is specific to an MFI structure exists between 22.5-25.0 degrees of 2 theta, and the molecular sieve is shown to have the MFI structure similar to TS-1. Fourier infrared spectrum at 960cm -1 The characteristic absorption peak which the all-silicon molecular sieve does not have appears in the vicinity, and the titanium enters the sample framework. The above characterization results show that the prepared molecular sieve is a titanium silicalite TS-1. The properties of the resulting molecular sieve particles are set forth in table 4.
Preparation of example 2
The titanium silicalite molecular sieve is produced by the same method as the preparation example 1, except that in the step (2), the condensate collected in the step (1) is not added into the reaction kettle, but the reaction kettle is directly sealed for hydrothermal crystallization after the hydrolysis condensation reaction is finished.
Through detection, in an XRD spectrogram of the obtained molecular sieve, a five-finger diffraction characteristic peak which is specific to an MFI structure exists between 22.5-25.0 degrees of 2 theta, and the molecular sieve is shown to have the MFI structure similar to TS-1. Fourier infrared spectrum at 960cm -1 The characteristic absorption peak which the all-silicon molecular sieve does not have appears in the vicinity, and the titanium enters the sample framework. The above characterization results show that the prepared molecular sieve is a titanium silicalite TS-1.
Preparation of comparative example 1
A titanium silicalite molecular sieve was produced in the same manner as in preparation example 1, except that in step (2), the condensate collected in step (1) was replaced with an equal weight of deionized water.
Through detection, five-finger diffraction characteristic peaks which are special for an MFI structure exist in the XRD crystal phase of the obtained molecular sieve between 22.5-25.0 degrees of 2 theta, and the molecular sieve is shown to have the MFI structure similar to TS-1. Fourier infrared spectrum at 960cm -1 The characteristic absorption peak which the all-silicon molecular sieve does not have appears in the vicinity, and the titanium enters the sample framework. The above characterization results show that the prepared molecular sieve is a titanium silicalite TS-1.
Preparation of comparative example 2
A titanium silicalite molecular sieve was produced in the same manner as in preparative example 1, except that in step (2), the condensate collected in step (1) was replaced with an equal weight of ethanol.
Through detection, five-finger diffraction characteristic peaks which are special for an MFI structure exist in the XRD crystal phase of the obtained molecular sieve between 22.5-25.0 degrees of 2 theta, and the molecular sieve is shown to have the MFI structure similar to TS-1. Fourier infrared spectrum at 960cm -1 The characteristic absorption peak which the all-silicon molecular sieve does not have appears in the vicinity, and the titanium enters the sample framework. The above characterization results show that the prepared molecular sieve is a titanium silicalite TS-1.
Preparation of comparative example 3
A titanium silicalite molecular sieve was produced in the same manner as in preparation example 1, except that in step (2), the condensate collected in step (1) was replaced with an equal weight of a mixture of water and ethanol (composition listed in table 2).
Through detection, five-finger diffraction characteristic peaks which are special for an MFI structure exist in the XRD crystal phase of the obtained molecular sieve between 22.5-25.0 degrees of 2 theta, and the molecular sieve is shown to have the MFI structure similar to TS-1. Fourier infrared spectrum at 960cm -1 The characteristic absorption peak which is not existed in the all-silicon molecular sieve appears near the sample, which indicates that the titanium enters the sample framework. The above characterization results show that the prepared molecular sieve is a titanium silicalite TS-1.
Preparation of comparative example 4
A titanium silicalite molecular sieve was produced in the same manner as in preparation example 1, except that in step (2), the condensate collected in step (1) was replaced with a mixed solution of water, ethanol and tetrapropylammonium hydroxide (composition shown in table 2) in equal weight.
Through detection, five-finger diffraction characteristic peaks which are special for an MFI structure exist in the XRD crystal phase of the obtained molecular sieve between 22.5-25.0 degrees of 2 theta, and the molecular sieve is shown to have the MFI structure similar to TS-1. Fourier infrared spectrum at 960cm -1 The characteristic absorption peak which the all-silicon molecular sieve does not have appears in the vicinity, and the titanium enters the sample framework. The above characterization results show that the prepared molecular sieve is a titanium silicalite TS-1.
Preparation of comparative example 5
The titanium silicalite molecular sieve is produced by the same method as the preparation example 2, except that in the step (3), the titanium silicalite molecular sieve TS-1 is not added into the reaction kettle, but the mixture obtained by hydrothermal crystallization is directly sprayed and formed.
Through detection, five-finger diffraction characteristic peaks which are special for an MFI structure exist in the XRD crystal phase of the obtained molecular sieve between 22.5-25.0 degrees of 2 theta, and the molecular sieve is shown to have the MFI structure similar to TS-1. Fourier infrared spectrum at 960cm -1 The characteristic absorption peak which the all-silicon molecular sieve does not have appears in the vicinity, and the titanium enters the sample framework. The above characterization results show that the prepared molecular sieve is a titanium silicalite TS-1.
Preparation of example 3
A titanium silicalite molecular sieve was produced in the same manner as in preparation example 1, except that, in step (1), the hydrolytic condensation reaction was carried out under the reaction conditions as listed in table 1.
Through detection, five-finger diffraction characteristic peaks which are special for an MFI structure exist in the XRD crystal phase of the obtained molecular sieve between 22.5-25.0 degrees of 2 theta, and the molecular sieve is shown to have the MFI structure similar to TS-1. Fourier infrared spectrum at 960cm -1 The characteristic absorption peak which the all-silicon molecular sieve does not have appears in the vicinity, and the titanium enters the sample framework. The above characterization results show that the prepared molecular sieve is a titanium silicalite TS-1.
Preparation of example 4
A titanium silicalite molecular sieve was produced in the same manner as in preparation example 1, except that, in step (1), the hydrolytic condensation reaction was carried out under the reaction conditions as listed in table 1.
Through detection, five-finger diffraction characteristic peaks which are special for an MFI structure exist in the XRD crystal phase of the obtained molecular sieve between 22.5-25.0 degrees of 2 theta, and the molecular sieve is shown to have the MFI structure similar to TS-1. Fourier infrared spectrum at 960cm -1 The characteristic absorption peak which the all-silicon molecular sieve does not have appears in the vicinity, and the titanium enters the sample framework. The above characterization results show that the prepared molecular sieve is a titanium silicalite TS-1.
Preparation of example 5
(1) Tetrapropylammonium hydroxide was mixed with deionized water at 25 ℃ and 1 atm under stirring for 1.5 hours to obtain an aqueous solution containing a template.
Tetraisopropyl titanate as a titanium source and tetraethyl orthosilicate (silicon ester 40, available from xila chemical trade co., york, hong kong) as an organosilicon source were mixed at 25 ℃ and 1 atm with stirring for 1.5 hours to obtain a mixture containing the titanium source and the organosilicon source.
Tetrapropylammonium hydroxide as a template, tetraisopropyl titanate as a titanium source, ethyl orthosilicate (silicon ester 40, available from sierkat chemical trade ltd, york, hong kong), which is an organic silicon source, and water were fed into a reaction vessel in the proportions listed in table 1, and a first hydrolytic condensation reaction and a second hydrolytic condensation reaction were sequentially carried out with stirring according to the reaction conditions listed in table 1 to obtain a hydrolytic condensation mixture, wherein the mass percentage of the condensate determining the end point of the hydrolytic condensation reaction to the organic silicon source is listed in table 1.
In the hydrolysis condensation reaction process, nitrogen is used for auxiliary purging, steam in the reaction kettle is taken out, the taken steam is condensed by adopting condensed water, the condensate enters a condensate storage tank, and the composition of the condensate is listed in table 2.
(2) After the hydrolysis condensation reaction is completed, the condensate collected in the step (1) is added into the reaction kettle and stirred for 2 hours at the temperature of 50 ℃. The amounts of condensate used relative to 100 parts by weight of the hydrolytic condensation mixture (on a dry basis) are listed in Table 3.
Next, the reaction vessel was sealed, the temperature in the reaction vessel was raised to the hydrothermal crystallization temperature, and hydrothermal crystallization was carried out under autogenous pressure, and the conditions of hydrothermal crystallization and the decomposition rate of the template agent during hydrothermal crystallization are shown in table 3.
After the hydrothermal crystallization is completed, the temperature in the reaction kettle is naturally reduced to 40 ℃, the reaction kettle is opened, the titanium silicalite TS-1 (prepared by the same method as in reference example 1) is added into the reaction kettle, and after stirring for 1 hour, the obtained slurry is output. The addition amount of the titanium silicalite TS-1 is shown in Table 3.
(3) The resulting slurry was spray molded and the resulting particles were calcined at 520 ℃ for 5 hours in air atmosphere to give molecular sieve particles, the spray molding conditions being listed in table 3.
Through detection, in an XRD spectrogram of the obtained molecular sieve, a five-finger diffraction characteristic peak which is specific to an MFI structure exists between 22.5-25.0 degrees of 2 theta, and the molecular sieve is shown to have the MFI structure similar to TS-1. Fourier infrared spectrum at 960cm -1 The characteristic absorption peak which the all-silicon molecular sieve does not have appears in the vicinity, and the titanium enters the sample framework. The above characterization results show that the prepared molecular sieve is a titanium silicalite TS-1. The properties of the resulting molecular sieve particles are set forth in table 4.
Preparation of example 6
The titanium silicalite molecular sieve is produced by the same method as that of preparation example 5, except that in the step (2), the condensate collected in the step (1) is not added into the reaction kettle, and the reaction kettle is directly sealed for hydrothermal crystallization after the hydrolysis condensation reaction is finished.
Through detection, in an XRD spectrogram of the obtained molecular sieve, a five-finger diffraction characteristic peak which is specific to an MFI structure exists between 22.5-25.0 degrees of 2 theta, and the molecular sieve is shown to have the MFI structure similar to TS-1. Fourier infrared spectrum at 960cm -1 The characteristic absorption peak which the all-silicon molecular sieve does not have appears in the vicinity, and the titanium enters the sample framework. The above characterization results show that the prepared molecular sieve is a titanium silicalite TS-1.
Preparation of comparative example 6
A titanium silicalite molecular sieve was produced in the same manner as in preparation example 5, except that in step (2), the condensate collected in step (1) was replaced with a mixed solution of water, ethanol and tetrapropylammonium hydroxide (composition shown in table 2) of equal weight.
Through detection, in an XRD spectrogram of the obtained molecular sieve, a five-finger diffraction characteristic peak which is specific to an MFI structure exists between 22.5-25.0 degrees of 2 theta, and the molecular sieve is shown to have the MFI structure similar to TS-1. Fourier infrared spectrum at 960cm -1 The characteristic absorption peak which the all-silicon molecular sieve does not have appears in the vicinity, and the titanium enters the sample framework. The above characterization results show that the prepared molecular sieve is a titanium silicalite TS-1.
Preparation of example 7
Titanium silicalite molecular sieves were produced in the same manner as in preparative example 5 except that the condensate was used in the amounts shown in Table 3 relative to 100 parts by weight of the hydrolytic condensation mixture (on a dry basis).
Through detection, in an XRD spectrogram of the obtained molecular sieve, a five-finger diffraction characteristic peak which is specific to an MFI structure exists between 22.5-25.0 degrees of 2 theta, and the molecular sieve is shown to have the MFI structure similar to TS-1. Fourier infrared spectrum at 960cm -1 The characteristic absorption peak which the all-silicon molecular sieve does not have appears in the vicinity, and the titanium enters the sample framework. The above characterization results show that the prepared molecular sieve is a titanium silicalite TS-1.
Preparation of example 8
(1) Tetrapropylammonium hydroxide was mixed with deionized water at 30 ℃ and 1 atm under stirring for 1 hour to obtain an aqueous solution containing a template.
Tetrabutyl titanate as a titanium source and ethyl orthosilicate (silicon ester 40, available from xiekatt chemical trade co., yokohong) as an organosilicon source were mixed at 30 ℃ and 1 atm under stirring for 1 hour to obtain a mixture containing the titanium source and the organosilicon source.
Feeding an aqueous solution containing a template agent and a mixture containing a titanium source and an organic silicon source into a reaction kettle according to the proportion listed in table 1, and carrying out a first hydrolytic condensation reaction and a second hydrolytic condensation reaction in sequence with stirring according to the reaction conditions listed in table 1 to obtain a hydrolytic condensation mixture, wherein the mass percentage of a condensate determining the end point of the hydrolytic condensation reaction in the organic silicon source is listed in table 1.
In the hydrolysis condensation reaction process, nitrogen is used for auxiliary purging, steam in the reaction kettle is taken out, the taken steam is condensed by adopting condensed water, the condensate enters a condensate storage tank, and the composition of the condensate is listed in table 2.
(2) After the hydrolysis condensation reaction is completed, the condensate collected in the step (1) is added into the reaction kettle and stirred for 1 hour at the temperature of 60 ℃. The amounts of condensate used relative to 100 parts by weight of the hydrolytic condensation mixture (on a dry basis) are listed in Table 3.
Next, the reaction vessel was sealed, the temperature in the reaction vessel was raised to the hydrothermal crystallization temperature, and hydrothermal crystallization was carried out under autogenous pressure, and the conditions of hydrothermal crystallization and the decomposition rate of the template agent during hydrothermal crystallization are shown in table 3.
After the hydrothermal crystallization is finished, after the temperature in the reaction kettle naturally drops to 40 ℃, the reaction kettle is opened, the titanium silicalite TS-1 (prepared by the same method as in reference example 1) is added into the reaction kettle, and after stirring for 3 hours, the obtained slurry is output. The addition amount of the titanium silicalite TS-1 is shown in Table 3.
(3) The resulting slurry was spray molded and the resulting particles were calcined at 500 ℃ for 6 hours in air atmosphere to give molecular sieve particles, the spray molding conditions being listed in table 3.
Through detection, in an XRD spectrogram of the obtained molecular sieve, a five-finger diffraction characteristic peak which is specific to an MFI structure exists between 22.5-25.0 degrees of 2 theta, and the molecular sieve is shown to have the MFI structure similar to TS-1. Fourier infrared spectrum at 960cm -1 The characteristic absorption peak which the all-silicon molecular sieve does not have appears in the vicinity, and the titanium enters the sample framework. The above characterization results show that the prepared molecular sieve is a titanium silicalite TS-1. The properties of the resulting molecular sieve particles are set forth in table 4.
Preparation of example 9
The titanium silicalite molecular sieve is produced by the same method as that of preparation example 8, except that in the step (2), the condensate collected in the step (1) is not added into the reaction kettle, and the reaction kettle is directly sealed for hydrothermal crystallization after the hydrolysis condensation reaction is finished.
Through detection, in an XRD spectrogram of the obtained molecular sieve, a five-finger diffraction characteristic peak which is specific to an MFI structure exists between 22.5-25.0 degrees of 2 theta, and the molecular sieve is shown to have the MFI structure similar to TS-1. Fourier infrared spectrum at 960cm -1 The characteristic absorption peak which the all-silicon molecular sieve does not have appears in the vicinity, and the titanium enters the sample framework. The above characterization results show that the prepared molecular sieve is a titanium silicalite TS-1.
Preparation of comparative example 7
A titanium silicalite molecular sieve was produced in the same manner as in preparative example 8, except that in step (2), the condensate collected in step (1) was replaced with a mixed solution of water, ethanol and tetrapropylammonium hydroxide (composition shown in table 2) of equal weight.
Through detection, in an XRD spectrogram of the obtained molecular sieve, a five-finger diffraction characteristic peak which is specific to an MFI structure exists between 22.5-25.0 degrees of 2 theta, and the molecular sieve is shown to have the MFI structure similar to TS-1. Fourier infrared spectrum at 960cm -1 The characteristic absorption peak which the all-silicon molecular sieve does not have appears in the vicinity, and the titanium enters the sample framework. The above characterization results show that the prepared molecular sieve is a titanium silicalite TS-1.
Preparation of comparative example 8
The titanium silicalite molecular sieve was produced in the same manner as in preparation example 9, except that in step (1), the hydrolysis condensation reaction was carried out without purging with nitrogen, and the vapor generated by the reaction was condensed and refluxed back to the reaction vessel. In the step (2), the condensate is not added into the reaction kettle, but the hydrolysis condensation mixture obtained in the step (1) is fed into the reaction kettle, stirred for 1 hour at the temperature of 60 ℃, and then the reaction kettle is sealed for hydrothermal crystallization.
Through detection, in an XRD spectrogram of the obtained molecular sieve, a five-finger diffraction characteristic peak which is specific to an MFI structure exists between 22.5-25.0 degrees of 2 theta, and the molecular sieve is shown to have the MFI structure similar to TS-1. Fourier infrared spectrum at 960cm -1 The characteristic absorption peak which the all-silicon molecular sieve does not have appears in the vicinity, and the titanium enters the sample framework. The above characterization results show that the prepared molecular sieve is a titanium silicalite TS-1.
Preparation of example 10
Titanium silicalite molecular sieves were produced in the same manner as in preparative example 8, except that the condensate was used in the amounts shown in Table 3 relative to 100 parts by weight of the hydrolytic condensation mixture (on a dry basis).
Through detection, in an XRD spectrogram of the obtained molecular sieve, a five-finger diffraction characteristic peak which is specific to an MFI structure exists between 22.5-25.0 degrees of 2 theta, and the molecular sieve is shown to have the MFI structure similar to TS-1. Fourier infrared spectrum at 960cm -1 The characteristic absorption peak which the all-silicon molecular sieve does not have appears in the vicinity, and the titanium enters the sample framework. The above characterization results show that the prepared molecular sieve is a titanium silicalite TS-1.
TABLE 1
TABLE 2
| Numbering | Alcohol content (% by weight) | Nitrogen content (mmol/L) |
| Preparation of example 1 | 90 | 1.23 |
| Preparation of comparative example 3 | 90 | 0 |
| Preparation of comparative example 4 | 90 | 1.23 |
| Preparation of example 3 | 82 | 2.39 |
| Preparation of example 4 | 95 | 0.09 |
| Preparation of example 5 | 89 | 0.89 |
| Preparation of comparative example 6 | 89 | 0.89 |
| Preparation of example 8 | 93 | 0.57 |
| Preparation of comparative example 7 | 92 | 0.53 |
TABLE 3
1 : the hydrothermal crystallization mixture is calculated on a dry basis relative to the addition amount of 1 part by weight of the hydrothermal crystallization mixture, and the dry basis refers to the mass of the hydrothermal crystallization mixture after being dried at 120 ℃ for 8 hours
TABLE 4
The results of preparation examples 2, 6 and 9 demonstrate that, by using the method of the present invention, the hydrothermal crystallization mixture obtained by hydrothermal crystallization can be directly spray-molded without adding an additional binder or a precursor thereof, and the particle size distribution of the titanium silicalite molecular sieve particles obtained by spray-molding is more uniform.
The results of preparation example 1, preparation comparative examples 1 to 4, preparation examples 5 and 6, preparation comparative examples 6, preparation examples 8 and 9 and preparation comparative example 7 prove that the titanium silicalite molecular sieve is prepared by the method of the invention, at least part of condensate generated in the hydrolysis condensation reaction process is mixed with the hydrolysis condensation mixture and then is subjected to hydrothermal crystallization, so that the invalid decomposition of the template agent in the hydrothermal crystallization process can be effectively inhibited, the amount of the recycled template agent is increased, the consumption of the template agent is reduced, and the production cost of the titanium silicalite molecular sieve is further reduced.
Experimental examples 1-10 are provided to illustrate the cyclohexanone ammoximation reaction method of the present invention.
Experimental examples 1 to 10
Experimental examples 1 to 10 the cyclohexanone ammoximation reaction was carried out by using the titanium silicalite molecular sieves prepared in preparation examples 1 to 10 as catalysts for the cyclohexanone ammoximation reaction, respectively, in the following manner.
The titanium silicalite molecular sieves prepared in preparation examples 1 to 10 were respectively loaded in a fixed bed reactor to form a catalyst bed (the aspect ratio of the catalyst bed was 5), cyclohexanone, ammonia, hydrogen peroxide (the concentration of hydrogen peroxide was 30 wt%) and a solvent were fed into the fixed bed reactor in the proportions shown in table 5, and the reaction was carried out under the reaction conditions shown in table 5 (the pressure in table 5 was gauge pressure). The reaction was continued for 80 hours. And collecting the reaction product output from the fixed bed reactor, measuring the composition of the reaction product, and calculating the conversion rate of cyclohexanone and the selectivity of caprolactam.
Each preparation example was repeated to prepare 3 batches of titanium silicalite molecular sieves, each batch of titanium silicalite molecular sieves was subjected to 3 sets of parallel experiments, each preparation example was subjected to 9 sets of experiments in total, and average values of cyclohexanone conversion and caprolactam selectivity obtained in the 9 sets of experiments were taken as the evaluation results of the catalytic performance of the titanium silicalite molecular sieves prepared in the preparation examples, and the specific results are listed in table 5.
Experimental comparative examples 1 to 8
The cyclohexanone ammoximation reaction was carried out in the same manner as in examples 1 to 10, except that the titanium silicalite molecular sieves prepared in comparative examples 1 to 8 were each used as a catalyst. The results of the experiment are listed in table 5.
Reference Experimental example 1
The cyclohexanone ammoximation reaction was carried out in the same manner as in examples 1 to 10, except that the titanium silicalite molecular sieve prepared in reference example 1 was used as the catalyst. The results of the experiment are listed in table 5.
TABLE 5
The results in Table 5 demonstrate that the titanium silicalite molecular sieve prepared by the method of the invention can obtain better catalytic performance as the catalyst of cyclohexanone ammoximation reaction.
The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.
Claims (48)
1. A method for producing a titanium silicalite molecular sieve, the method comprising:
(1) carrying out a first hydrolysis condensation reaction on an organic silicon source, a titanium source, a template agent and water to obtain a first hydrolysis condensation mixture, carrying out a second hydrolysis condensation reaction on the first hydrolysis condensation mixture to obtain a second hydrolysis condensation mixture, wherein the first hydrolysis condensation reaction is carried out at the temperature of 35-80 ℃;
(2) carrying out hydrothermal crystallization on the obtained second hydrolysis condensation mixture to obtain a hydrothermal crystallization mixture, wherein the second hydrolysis condensation reaction is carried out at the temperature of 70-98 ℃;
(3) mixing the hydrothermal crystallization mixture with a supplementary titanium silicalite molecular sieve to obtain slurry, and carrying out spray forming on the slurry;
the method is characterized in that in the processes of the first hydrolysis-condensation reaction and the second hydrolysis-condensation reaction, generated vapor is led out and condensed to obtain condensate, when the mass of the condensate is 0.5-0.8 times of the total mass of the organic silicon source, the reaction kettle is sealed, the condition in the reaction kettle is adjusted to be hydrothermal crystallization condition, hydrothermal crystallization is carried out, and at least part of the condensate is mixed with the second hydrolysis-condensation mixture before the reaction kettle is sealed.
2. The method according to claim 1, wherein in the step (1), the molar ratio of the organic silicon source, the titanium source, the template and the water is 100: (0.005-10): (0.005-40): (200-10000), the organic silicon source is SiO 2 The titanium source is calculated as TiO 2 In terms of NH, the template agent 3 And (6) counting.
3. The method according to claim 1, wherein in step (1), the organic solvent is usedThe molar ratio of the silicon source to the titanium source to the template to the water is 100: (0.05-8): (0.5-30): (500-5000), the organic silicon source is SiO 2 The titanium source is calculated as TiO 2 In terms of NH, the template agent 3 And (6) counting.
4. The method according to claim 1, wherein in the step (1), the molar ratio of the organic silicon source, the titanium source, the template and the water is 100: (0.2-8): (5-25): (800-4000), the organic silicon source is SiO 2 The titanium source is calculated as TiO 2 In terms of NH, the template agent 3 And (6) counting.
5. The method according to claim 1, wherein in the step (1), the molar ratio of the organic silicon source, the titanium source, the template and the water is 100: (1-6): (10-20): (1200-3000), the organic silicon source is SiO 2 The titanium source is calculated as TiO 2 In terms of NH, the template agent 3 And (6) counting.
6. The method according to any one of claims 1 to 5, wherein the organic silicon source is selected from silicon-containing compounds of formula I,
in the formula I, R 1 、R 2 、R 3 And R 4 Each is C 1 -C 4 Alkyl group of (1).
7. The method according to any one of claims 1 to 5, wherein the organic silicon source is one or more selected from the group consisting of methyl orthosilicate, ethyl orthosilicate, n-propyl orthosilicate, isopropyl orthosilicate, and n-butyl orthosilicate.
8. The method of any one of claims 1-5, wherein the titanium source is TiCl 4 、Ti(SO 4 ) 2 、TiOCl 2 Titanium hydroxide, oxideOne or more of titanium, titanium nitrate, titanium phosphate, tetraisopropyl titanate, tetra-n-propyl titanate, tetrabutyl titanate and tetraethyl titanate
9. The method of any one of claims 1-5, wherein the templating agent is one or more of urea, amine, alcohol amine, and quaternary ammonium base.
10. The method of any one of claims 1-5, wherein the templating agent is a quaternary ammonium base represented by formula II,
in the formula II, R 5 、R 6 、R 7 And R 8 Identical or different, are each C 1 -C 4 Alkyl of (a), said C 1 -C 4 Alkyl of (2) includes C 1 -C 4 Straight chain alkyl of (2) and C 3 -C 4 Branched alkyl groups of (a).
11. The method of claim 10, wherein, in formula II, R 5 、R 6 、R 7 And R 8 Each methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl or tert-butyl.
12. The method of any one of claims 1-5, wherein the templating agent is tetraethylammonium hydroxide and/or tetrapropylammonium hydroxide.
13. The process according to claim 1, wherein the condensate is used in an amount of 1 to 50 parts by weight relative to 100 parts by weight of the second hydrolytic condensation mixture.
14. The process according to claim 1, wherein the condensate is used in an amount of 2 to 40 parts by weight relative to 100 parts by weight of the second hydrolytic condensation mixture.
15. The process according to claim 1, wherein the condensate is used in an amount of 5 to 30 parts by weight relative to 100 parts by weight of the second hydrolytic condensation mixture.
16. The process according to claim 1, wherein the condensate is used in an amount of 10 to 25 parts by weight relative to 100 parts by weight of the second hydrolytic condensation mixture.
17. The method of any of claims 1 and 13-16, wherein mixing at least a portion of the condensate with the second hydrolytic condensation mixture comprises: the second hydrolytic condensation mixture is mixed with the condensate at 20-80 ℃ for 1-6 hours with stirring.
18. The method according to claim 17, wherein the second hydrolytic condensation mixture is mixed with the condensate at 40-60 ℃ for 1-3 hours with stirring.
19. A method according to any one of claims 1 and 13 to 16, wherein the condensate comprises water and alcohol, the alcohol being present in an amount of 80 to 96 wt% and the water being present in an amount of 4 to 20 wt%, based on the total amount of the condensate.
20. A method according to any one of claims 1 and 13 to 16, wherein the condensate comprises water and alcohol, the alcohol being present in an amount of 83 to 95 wt% and the water being present in an amount of 5 to 17 wt%, based on the total amount of the condensate.
21. A method according to any one of claims 1 and 13 to 16, wherein the condensate comprises water and alcohol, the alcohol being present in an amount of 88 to 92 wt% and the water being present in an amount of 8 to 12 wt%, based on the total amount of the condensate.
22. The method of any one of claims 1 and 13-16, wherein the condensate contains nitrogen.
23. The method of claim 22, wherein the concentration of elemental nitrogen in the condensate is 0.01 to 50 mmol/L.
24. The method of claim 22, wherein the concentration of elemental nitrogen in the condensate is 0.02 to 20 mmol/L.
25. The method of claim 22, wherein the concentration of elemental nitrogen in the condensate is 0.04 to 5 mmol/L.
26. The method of claim 22, wherein the concentration of elemental nitrogen in the condensate is 0.05 to 3 mmol/L.
27. The method of claim 22, wherein the concentration of elemental nitrogen in the condensate is 0.5 to 1.5 mmol/L.
28. The process according to claim 1, wherein the first hydrolytic condensation reaction is carried out at a temperature of 40-60 ℃.
29. The process according to claim 1 or 28, wherein the duration of the first hydrolytic condensation reaction is from 1 to 20 hours.
30. The process according to claim 1 or 28, wherein the duration of the first hydrolytic condensation reaction is from 5 to 18 hours.
31. The process according to claim 1 or 28, wherein the duration of the first hydrolytic condensation reaction is 10-15 hours.
32. The process according to claim 1, wherein the second hydrolytic condensation reaction is carried out at a temperature of 80-96 ℃.
33. The process according to claim 1, wherein the second hydrolytic condensation reaction is carried out at a temperature of 90-95 ℃.
34. The method of any one of claims 1, 32 and 33, wherein the duration of the second hydrolytic condensation reaction is from 1 to 15 hours.
35. The method of any one of claims 1, 32 and 33, wherein the duration of the second hydrolytic condensation reaction is 3-12 hours.
36. The method of any one of claims 1, 32 and 33, wherein the duration of the second hydrolytic condensation reaction is 6-10 hours.
37. The method as claimed in claim 1, wherein, in the step (2), the hydrothermal crystallization is performed at a temperature of 120-190 ℃.
38. The method as claimed in claim 1, wherein, in the step (2), the hydrothermal crystallization is performed at a temperature of 140 ℃ and 185 ℃.
39. The method as claimed in claim 1, wherein, in the step (2), the hydrothermal crystallization is performed at a temperature of 160-180 ℃.
40. The method according to any one of claims 1 and 37 to 39, wherein the duration of the hydrothermal crystallization in step (2) is 6 to 30 hours.
41. The method according to any one of claims 1 and 37 to 39, wherein the duration of the hydrothermal crystallization in step (2) is 9 to 25 hours.
42. The method as claimed in any one of claims 1 and 37 to 39, wherein when the mass of the condensed liquid is 0.55 to 0.75 times the total mass of the organic silicon source, the hydrothermal crystallization is performed by sealing the reaction vessel and adjusting the conditions in the reaction vessel to hydrothermal crystallization conditions.
43. The method of claim 1, wherein in step (3), the weight ratio of the supplemental titanium silicalite molecular sieve to the hydrothermal crystallization mixture is 0.01-10: 1, the hydrothermal crystallization mixture is on a dry basis.
44. The method of claim 1, wherein in step (3), the weight ratio of the supplemental titanium silicalite molecular sieve to the hydrothermal crystallization mixture is from 0.05 to 8: 1, the hydrothermal crystallization mixture is on a dry basis.
45. The method of claim 1, wherein in step (3), the weight ratio of the supplemental titanium silicalite molecular sieve to the hydrothermal crystallization mixture is 0.2-5: 1, the hydrothermal crystallization mixture is on a dry basis.
46. The method of claim 1, wherein in step (3), the weight ratio of the supplemental titanium silicalite molecular sieves to the hydrothermal crystallization mixture is from 0.4 to 3.5: 1, the hydrothermal crystallization mixture is on a dry basis.
47. A titanium silicalite molecular sieve produced by the method of any one of claims 1 to 46.
48. A cyclohexanone ammoximation reaction method, which comprises contacting cyclohexanone, ammonia and hydrogen peroxide with a titanium silicalite molecular sieve under ammoximation reaction conditions, wherein the titanium silicalite molecular sieve is the titanium silicalite molecular sieve of claim 47.
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