CN116332198A - Titanium silicon molecular sieve, preparation method thereof and method for catalytic oxidation of cycloalkane - Google Patents

Titanium silicon molecular sieve, preparation method thereof and method for catalytic oxidation of cycloalkane Download PDF

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CN116332198A
CN116332198A CN202111578457.7A CN202111578457A CN116332198A CN 116332198 A CN116332198 A CN 116332198A CN 202111578457 A CN202111578457 A CN 202111578457A CN 116332198 A CN116332198 A CN 116332198A
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titanium
molecular sieve
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silicalite molecular
silicon
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刘聿嘉
赵辰阳
朱红伟
王世强
孙冰
徐伟
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China Petroleum and Chemical Corp
Sinopec Safety Engineering Research Institute Co Ltd
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Abstract

The invention relates to the technical field of catalytic oxidation of cycloalkanes, in particular to a titanium silicon molecular sieve, a preparation method thereof and a method for catalytic oxidation of cycloalkanes. The aperture of the titanium silicalite molecular sieve is 0.1-2nm, and the specific surface area is 440-580m 2 Per gram, a total pore volume of 0.4-0.6cm 3 /g; the external surface area is 50-200m 2 Per gram, micropore volume of 0.13-0.20cm 3 /g; the particle size of the molecular sieve particles is 100-250nm; the crystallinity of the molecular sieve is more than or equal to 50 percent. The invention is generalThe titanium silicasol precursor is treated by a specific silanization reagent, and when the prepared titanium silicasol molecular sieve is applied to catalytic oxidation cycloparaffin reaction, the titanium silicasol molecular sieve has high catalytic activity, and the conversion rate of cycloparaffin can be improved to more than 91%.

Description

Titanium silicon molecular sieve, preparation method thereof and method for catalytic oxidation of cycloalkane
Technical Field
The invention relates to the technical field of catalytic oxidation of cycloalkanes, in particular to a titanium silicon molecular sieve, a preparation method thereof and a method for catalytic oxidation of cycloalkanes.
Background
Catalytic oxidation is an important synthetic reaction and has wide application in the fields of petrochemical industry and fine chemical industry. For example, the catalytic oxidation of cyclohexane to produce cyclohexanone and cyclohexanol is currently the dominant worldwide process for producing cyclohexanol and cyclohexanone. Cyclohexanone, a colorless transparent liquid, is slightly soluble in water and can be mixed with organic solvents such as ethanol, acetone and the like. Cyclohexanol, colorless transparent oily liquid or white needle crystal, has camphora-like smell, and can be mixed with ethanol, ethyl acetate and aromatic hydrocarbon. Cyclohexanone and cyclohexanol are industrially used mainly as raw materials for organic synthesis for the production of nylon, caprolactam, adipic acid, etc. The industrial catalytic cyclohexane oxidation mainly adopts cobalt catalyst (soluble cobalt salt), but the process is easy to slag on equipment and pipeline walls, and by-products such as carboxylic acid and the like are produced. The separation and recycling reaction are needed for a large amount of unconverted cyclohexane, and the energy consumption is high. Therefore, the development of new catalytic oxidation systems to obtain high cyclohexane conversion and cyclohexanone, cyclohexanol yields is an important research objective.
Molecular sieve catalysts are heterogeneous catalysts commonly used in the chemical industry, which are not only easy to separate and recycle, but also can obtain specific catalytic activity by introducing different metal atoms into the molecular sieve framework. For example, a titanium-silicon molecular sieve obtained by inserting titanium atoms into a molecular sieve framework and hydrogen peroxide can form a catalytic oxidation system, and has excellent catalytic effect on various oxidation reactions. This is because the empty orbitals of the framework titanium atoms can receive lone electron pairs of hydrogen peroxide, thereby forming Ti-OOH catalytically active sites.
CN108726528A discloses a hierarchical pore titanium-silicon molecular sieve, a preparation method thereof and a method for olefin epoxidation, a certain proportion of mesoporous pore canal can be introduced into the titanium-silicon molecular sieve through treatment of a silanization reagent, and although mass transfer diffusion of reaction molecules is facilitated, part of active centers lost at the same time may cause reduction of catalytic oxidation performance of the molecular sieve.
Disclosure of Invention
The invention aims to improve the catalytic oxidation performance of a titanium silicalite molecular sieve in a catalytic oxidation cycloparaffin reaction, and provides the titanium silicalite molecular sieve, a preparation method thereof and a method for catalytic oxidation cycloparaffin.
In order to achieve the above object, a first aspect of the present invention provides a titanium silicalite molecular sieve having a pore size of 0.1 to 2nm and a specific surface area of 440 to 580m 2 Per gram, a total pore volume of 0.4-0.6cm 3 /g; the external surface area is 50-200m 2 Per gram, micropore volume of 0.13-0.2cm 3 /g; the particle size of the molecular sieve particles is 100-250nm; the crystallinity of the molecular sieve is more than or equal to 50 percent.
In a second aspect, the present invention provides a method of preparing a titanium silicalite molecular sieve, the method comprising:
(1) Uniformly mixing a silicon source, an alkaline template agent, a titanium source, water and isopropanol to obtain titanium silicasol;
(2) Adding a compound shown in a formula (I) into the titanium silicasol, and carrying out hydrothermal crystallization and roasting on the obtained mixture;
Figure BDA0003426181160000021
wherein i is an integer of 1 to 6; r is R 1 、R 2 And R is 3 Each independently selected from C 1 -C 6 Is a hydrocarbon group.
In a third aspect, the present invention provides a titanium silicalite molecular sieve prepared according to the method of the second aspect.
In a fourth aspect, the present invention provides a method of catalytic oxidation of a cycloalkane, the method comprising: the cycloalkane and peroxide are contacted to react in the presence of a catalyst comprising the titanium silicalite molecular sieve of the first aspect or the third aspect.
According to the technical scheme, the titanium silicasol precursor is treated by the specific silanization reagent, so that the prepared titanium silicasol molecular sieve with specific parameters has high catalytic activity when being applied to catalytic oxidation of cycloparaffin, and the conversion rate of cycloparaffin can be improved to more than 91%.
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FIG. 1 is a graph showing pore size distribution of a titanium silicalite molecular sieve obtained in example 1 of the present invention;
FIG. 2 is N of a titanium silicalite molecular sieve obtained in example 1 of the present invention 2 An adsorption and desorption curve graph;
FIG. 3 is a TEM image of a titanium silicalite molecular sieve obtained in example 1 of the present invention;
FIG. 4 is an XRD pattern of a titanium silicalite molecular sieve obtained in example 1 of the present invention;
FIG. 5 is a graph showing the pore size distribution of the titanium silicalite molecular sieve obtained in comparative example 1.
Detailed Description
The endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and are understood to encompass values approaching those ranges or values. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein.
As described above, the first aspect of the present invention provides a titanium silicalite molecular sieve having a pore size of 0.1-2nm and a specific surface area of 440-580m 2 Per gram, a total pore volume of 0.4-0.6cm 3 /g; the external surface area is 50-200m 2 Per gram, micropore volume of 0.13-0.2cm 3 /g; the particle size of the molecular sieve particles is 100-250nm; the crystallinity of the molecular sieve is more than or equal to 50 percent.
According to the invention, the molar ratio of titanium to silicon in the titanium-silicon molecular sieve is preferably 0.001-0.04:1, preferably 0.005-0.025:1.
in some preferred embodiments of the present invention, the titanium silicalite molecular sieve has an external surface area of 120-200m 2 Preferably 150-200m 2 /g。
According to the invention, the specific surface area of the titanium silicalite molecular sieve is 460-490m under the preferable condition 2 /g。
In the invention, the external surface area of the titanium silicalite molecular sieve refers to the surface area of the external surface of the titanium silicalite molecular sieve, and can be obtained by testing by a BET method; the specific surface area of the titanium silicalite molecular sieve is referred to as BET specific surface area.
According to the invention, the particle size of the titanium silicalite molecular sieve is preferably 150-240nm.
According to the invention, in the infrared spectrum of the titanium silicalite molecular sieve, the wave number is 960cm under the preferable condition -1 The peak area and wave number of the obtained product were 800cm -1 The ratio of the peak-to-peak area is 0.4 to 1.5.
In a second aspect, the present invention provides a method of preparing a titanium silicalite molecular sieve, the method comprising:
(1) Uniformly mixing a silicon source, an alkaline template agent, a titanium source, water and isopropanol to obtain titanium silicasol;
(2) Adding a compound shown in a formula (I) into the titanium silicasol, and carrying out hydrothermal crystallization and roasting on the obtained mixture;
Figure BDA0003426181160000041
wherein i is an integer of 1 to 6; r is R 1 、R 2 And R is 3 Each independently selected from C 1 -C 6 Is a hydrocarbon group.
In the invention, C 1 -C 6 The alkyl group of (a) means an alkyl group having 1 to 6 carbon atoms in total, and may be, for example, one of methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl and n-hexyl.
In some preferred embodiments of the invention i is an integer from 1 to 5, which may be 1, 2, 3, 4 or 5, for example.
In some preferred embodiments of the invention, R 1 、R 2 And R is 3 Each independently selected from C 1 -C 3 Alkyl group of said C 1 -C 3 The alkyl group of (a) may be methyl, ethyl, n-propyl or isopropyl, preferably R 1 、R 2 And R is 3 Each independently selected from methyl, ethyl or n-propyl. In the present invention, R 1 、R 2 And R is 3 May be the same or different, and R is preferably selected from 1 、R 2 And R is 3 All the same.
In the invention, by adopting the compound shown in the formula (I) as a silylating agent, a titanium silicon molecular sieve with a full microporous structure can be formed through weak intermolecular interaction force among alkyl chains of the silylating agent in the hydrothermal crystallization reaction process, and the titanium silicon molecular sieve has high specific surface area and pore volume, is beneficial to the intragranular and intergranular mass transfer diffusion of reactant molecules and product molecules during the catalytic oxidation of cycloalkane reaction, and can be used for basically completely converting cycloalkane into cyclic ketone and cyclic alcohol.
According to the present invention, too high an amount of the silylating agent (compound represented by formula (I)) may result in poor crystallization properties of the titanium silicasol, failing to obtain the molecular sieve; the use level of the silylation reagent (the compound shown in the formula (I)) is too low, so that the specific surface area of the obtained titanium-silicon molecular sieve is reduced, mass transfer is influenced, and the activity of the titanium-silicon molecular sieve on the cycloalkane catalytic oxidation reaction is further influenced; preferably, in step (1), the silicon source is selected from the group consisting of SiO 2 The molar ratio of the silicon source to the compound represented by formula (I) is 1: (0.01-0.3), preferably 1: (0.01-0.2); more preferably 1: (0.05-0.2).
In some preferred embodiments of the invention, the silicon source is in the form of SiO 2 Calculated by N when the alkaline template agent contains nitrogen element, and calculated by OH when the alkaline template agent does not contain nitrogen element - The molar ratio of the silicon source to the alkaline template to the water is 1: (0.05-0.4): (5-40 A) is provided; preferably 1: (0.1-0.3): (5-25).
According to the present invention, preferably, the silicon source is at least one selected from the group consisting of tetramethyl silicate, tetraethyl silicate, tetrapropyl silicate, tetrabutyl silicate, silica gel, white carbon black, and silica sol.
According to the present invention, preferably, the basic template is at least one selected from the group consisting of quaternary ammonium base, aliphatic amine and aliphatic alcohol amine, preferably at least one selected from the group consisting of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide and tetrabutylammonium hydroxide.
In some preferred embodiments of the invention, the silicon source is in the form of SiO 2 The titanium source is calculated as TiO 2 The molar ratio of the silicon source, the titanium source and the isopropanol is 1: (0.001-0.04): (0.1-10), preferably 1: (0.005-0.025): (0.1-5).
According to the present invention, preferably, the titanium source is selected from an organic titanium source and/or an inorganic titanium source; further preferably, the titanium source is selected from at least one of titanium tetrachloride, titanium sulfate, titanium nitrate, tetraethyl titanate, tetrapropyl titanate, and tetrabutyl titanate.
According to the present invention, preferably, step (1) further includes: mixing a silicon source, an alkaline template agent and water through first stirring to obtain a mixed system; and then dropwise adding the mixed solution of the titanium source and the isopropanol into the mixed system for second stirring to obtain a mixed solution.
In the invention, the dripping rate of the mixed solution is preferably 0.01-0.5mL/min; further preferably 0.1 to 0.5mL/min.
In the present invention, preferably, the time of the first stirring is 0.1 to 2 hours.
In the present invention, preferably, the second stirring time is 0.5 to 6 hours, preferably 0.5 to 3 hours.
In the present invention, preferably, step (1) further includes: alcohol expelling is carried out on the mixed solution; alcohol removal can remove alcohol generated by hydrolysis of a silicon source and a titanium source, in the invention, the alcohol generated in a system is preferably removed by adopting an azeotropic distillation mode, and meanwhile, water lost by azeotropic distillation is supplemented in the alcohol removal process, so that the proportion of each substance in the titanium silicasol is ensured to meet the requirements; preferably, the alcohol expelling conditions include: the temperature is 30-100 ℃ and the time is 2-10h; preferably at 40-90deg.C for 4-10 hr.
According to the present invention, in order to enable the silylating agent to be uniformly dispersed in the titanium silicasol, preferably, the step (1) further comprises: the compound shown in the formula (I) is added into the titanium silicasol for third stirring for 0.1-24h, preferably for 0.5-10h, and more preferably for 1-3h.
According to the invention, the nucleation and growth rate of the molecular sieve in a low-temperature state can be controlled by rapid temperature rise, so that molecular sieve particles with smaller size are obtained; according to the present invention, preferably, in step (2), the conditions for hydrothermal crystallization include: heating the mixture to 50-200 ℃ within 0.1-1h, and then carrying out hydrothermal crystallization for 10-100h at 50-200 ℃; preferably, the hydrothermal crystallization is carried out at the temperature of 100-200 ℃ for 20-80 hours; further preferably, the heating time is 0.1 to 0.5h; more preferably, the conditions for hydrothermal crystallization include: the temperature is 120-180 ℃ and the time is 20-80h; under the above preferred conditions, molecular sieve crystallinity, specific surface area and pore volume can be balanced; molecular sieves with specific crystallinity, specific surface area and pore volume are prepared.
The pressure of the hydrothermal crystallization is not particularly limited, and may be the autogenous pressure of the crystallization system.
According to the present invention, preferably, the method further comprises: washing, filtering and drying a product obtained by hydrothermal crystallization; wherein the washing, filtering and drying processes may be known to those skilled in the art, respectively. Illustratively, the temperature of the washing may be 20-50 ℃, the solvent for washing may be water, and the amount of the solvent for washing is 1-20 times the mass of the crystallized product; the drying conditions may be: the temperature is 40-150 ℃ and the time is 0.5-24h.
In some preferred embodiments of the invention, the firing conditions include: the temperature is 400-800 ℃ and the time is 1-15h; preferably 500-600deg.C for 4-10 hr.
In a third aspect, the present invention provides a titanium silicalite molecular sieve prepared according to the method of the second aspect.
Preferably, the aperture of the titanium silicalite molecular sieve is 0.1-2nm, and the specific surface area is 440-580m 2 Per gram, a total pore volume of 0.4-0.6cm 3 /g; the external surface area is 50-200m 2 Per gram, micropore volume of 0.13-0.2cm 3 /g; the particle size of the molecular sieve particles is 100-250nm; the crystallinity of the molecular sieve is more than or equal to 50%; more preferably, the molar ratio of titanium to silicon in the titanium-silicon molecular sieve is 0.001-0.04:1, preferably 0.005-0.025:1, a step of; further preferably, in the infrared spectrum of the titanium silicalite molecular sieve, the wave number is 960cm -1 The peak area and wave number of the obtained product were 800cm -1 The ratio of the peak-to-peak area is 0.4 to 1.5.
Further preferably, the titanium silicalite molecular sieve has high activity for catalyzing cyclohexane oxidation reaction, in which conversion rate of naphthenes is increased to 90% or more.
In a fourth aspect, the present invention provides a method of catalytic oxidation of a cycloalkane, the method comprising: the cycloalkane and peroxide are contacted to react in the presence of a catalyst comprising the titanium silicalite molecular sieve of the first or third aspect.
According to the invention, preferably the cycloalkane is selected from C 3 -C 15 Is preferably C 4 -C 8 Is a cycloalkane of (2); more preferably at least one of cyclohexane, cyclopentane and methylcyclohexane, most preferably cyclohexane.
According to the present invention, preferably, the peroxide is at least one selected from t-butyl hydroperoxide, cyclohexyl hydroperoxide, isopropyl hydroperoxide, cumene hydroperoxide, hydrogen peroxide, sodium percarbonate and sodium perborate.
In some preferred embodiments of the invention, the reaction conditions include: the weight ratio of the catalyst to the cycloalkane is 1: (1-20); the molar ratio of cycloalkane to peroxide is 1: (0.1-10); further preferably, the reaction conditions further include: the temperature is 40-100deg.C, and the time is 1-8h.
In some embodiments of the present invention, the form of the catalyst may be selected according to actual requirements, and the catalyst may be a molecular sieve supported on a carrier, or may be molecular sieve powder; in the present invention, it is preferable to directly use molecular sieve powder as a catalyst.
According to a particularly preferred embodiment of the present invention, the method for preparing a titanium silicalite molecular sieve comprises:
(1) The silicon source, the alkaline template agent and water are mixed according to the mole ratio of 1: (0.1-0.3): (5-25), after mixing, performing first stirring for 0.1-2h at room temperature, then dropwise adding the mixed solution of the titanium source and the isopropanol into the mixed system at the rate of 0.1-0.5mL/min, and performing second stirring for 0.5-3h to obtain a mixed solution; wherein the molar ratio of the silicon source, the titanium source and the isopropanol is 1: (0.005-0.025): (0.1-5);
then alcohol is removed from the mixed system to obtain titanium silicasol; the alcohol expelling temperature is 40-90 ℃ and the time is 4-10h;
(2) Adding a compound shown in a formula (I) into the titanium silicasol, and carrying out hydrothermal crystallization and roasting on the obtained mixture; wherein the molar ratio of the silicon source to the compound represented by formula (I) is 1: (0.01-0.2), the crystallization conditions are: heating the mixture to 150-180 ℃ within 0.5-1h, and then carrying out hydrothermal crystallization for 12-48h at 150-180 ℃;
Figure BDA0003426181160000081
wherein i is an integer of 1 to 5; r is R 1 、R 2 And R is 3 Are all the same; r is R 1 、R 2 And R is 3 Selected from methyl, ethyl or propyl.
The present invention will be described in detail by examples. In the examples below, room temperature is 25.+ -. 5 ℃.
In the following examples and comparative examples, X-ray diffraction (XRD) pattern measurements of samples were performed on a Siemens D5005 type X-ray diffractometer with a source of cuka tube voltage 40kV, tube current 40mA, scan speed 0.5 °/min, scan range 2θ=5° -35 °. According to XRD spectrogram, the crystallinity is obtained by fitting software eva of BRUKER;
the external surface area and specific surface area were both measured as static N of the sample at liquid nitrogen temperature (77.4K) using ASAP2405J static nitrogen adsorber from Micromeritics 2 After the adsorption and desorption curves, performing BET fitting on the adsorption curves to obtain;
pore volume was measured according to the method described in RIPP 151-90 in petrochemical analysis method (first edition, published by scientific Press 1990, 9) written by Yang Cuiding et al;
the pore size distribution is calculated according to the BJH formula;
the particle size was characterized by JEOL JEM-2100 Transmission Electron Microscopy (TEM);
the ultraviolet-visible spectrum (UV-Vis) of the sample was obtained by Agilent Cary 300 ultraviolet spectrophotometer testing, with a wavelength spacing of 3nm, and a scan range of 190-800nm.
In the following examples, the chemical structural formulas of the silylating agents employed are shown in table 1, and compound 1, compound 2 and compound 3 are all commercially available.
TABLE 1
Figure BDA0003426181160000091
Figure BDA0003426181160000101
Example 1
(1) Mixing tetraethyl silicate, tetrapropylammonium hydroxide and water at room temperature under first stirring to obtain a mixed system, dropwise adding the mixed solution of tetrabutyl titanate and isopropanol into the mixed system at a rate of 0.2mL/min in the stirring process, and carrying out second stirring for 0.5h to obtain a mixed solution; tetraethyl silicate in the form of SiO 2 Tetrapropylammonium hydroxide in N, tetrabutyltitanate in TiO 2 Meter, tetraethyl silicate, tetrapropylammonium hydroxideThe molar ratio of water is 1:0.1:15; the molar ratio of the tetraethyl silicate, the tetrabutyl titanate and the isopropanol is 1:0.005:3, a step of;
then alcohol expelling is carried out on the mixed solution at 80 ℃ for 6 hours to obtain titanium silicasol;
(2) Adding the compound (1) into the titanium silicasol, and carrying out third stirring for 1.5 hours at room temperature to obtain a mixture, wherein the molar ratio of the compound (1) to the tetraethyl silicate is 0.1:1;
(3) Heating the mixture to 170 ℃ for 0.5h, and performing hydrothermal crystallization for 24h at 170 ℃ to obtain a crystallized product; sequentially leaching the crystallized product with water, filtering, and drying at 120 ℃ for 2 hours;
roasting the dried product at 550 ℃ for 6 hours to obtain a titanium-silicon molecular sieve;
the pore size distribution of the titanium silicalite molecular sieve obtained in this example is shown in FIG. 1, N 2 The absorption and desorption curve chart is shown in figure 2; as can be seen from fig. 1 and 2, the titanium silicalite molecular sieve obtained in this example contains only micropores with a pore diameter of about 0.55 nm;
the TEM image of the titanium silicalite molecular sieve obtained in this example is shown in fig. 3, and it can be seen from fig. 3 that the particle size of the titanium silicalite molecular sieve obtained in this example is about 100-150nm;
as can be seen from FIG. 4, the XRD spectrum of the titanium silicalite molecular sieve obtained in the embodiment has an MFI structure and good crystallization performance;
physical properties of the titanium silicalite molecular sieves obtained in this example are shown in Table 3.
Examples 2 to 20
Titanium silicalite molecular sieves were prepared according to the procedure of example 1, the proportions and synthesis conditions of which are shown in Table 2, and the physical properties of the molecular sieves prepared are shown in Table 3.
Comparative example 1
Titanium silicalite molecular sieves were prepared according to the method of CN106145151B example 1, the specific method being as follows:
mixing tetraethyl silicate, tetrapropylammonium hydroxide, tetrabutyl titanate and deionized water to obtain SiO with the molar ratio of 2 : structure directing agent: tiO (titanium dioxide) 2 ：H 2 O=1: 0.2:0.025: 50. Then according to SiO 2 The molar ratio with the silylating agent is 1:0.1, siO 2 The weight ratio of the natural polymer compound to the natural polymer compound is 1:0.1, adding quaternized cellulose and N-phenyl-3-aminopropyl trimethoxy silane into a titanium silicalite molecular sieve precursor gel mixture, uniformly stirring, and transferring the obtained silanization reagent and the titanium silicalite molecular sieve precursor treated by the modified natural polymer compound into a pressure-resistant stainless steel reaction kettle; under stirring, heating to 170℃and crystallizing under autogenous pressure for 24h. After the stainless steel pressure-resistant reaction kettle is cooled to room temperature, the obtained unfired titanium-silicon molecular sieve is recovered, and after the unfired titanium-silicon molecular sieve is dried for 6 hours at 110 ℃, the unfired titanium-silicon molecular sieve is roasted for 4 hours at 550 ℃ to obtain the hierarchical pore titanium-silicon molecular sieve TS-1. The pore size distribution is shown in FIG. 5, and the product characteristics are shown in Table 3.
Comparative examples 2 to 6
Titanium silicalite molecular sieves were prepared as described in example 1, with the proportions and synthesis conditions shown in Table 2 and the physical properties of the molecular sieves prepared are shown in Table 3.
Comparative example 7
A titanium silicalite molecular sieve was prepared as in example 1, except that the silylating agent (compound 4) was methyltriethoxysilane, the proportions and synthesis conditions of which are shown in Table 2, and the physical properties of the molecular sieve prepared are shown in Table 3.
Comparative example 8
A titanium silicalite molecular sieve was prepared as in example 1, except that the silylating agent (compound 5) was octyltriethoxysilane, the proportions and synthesis conditions of which are shown in Table 2, and the physical properties of the molecular sieve prepared are shown in Table 3.
Test case
The test example demonstrates the reaction effect of the titanium silicalite molecular sieves prepared by the example samples and the comparative examples provided by the invention for preparing cyclohexanol and cyclohexanone by cyclohexane oxidation reaction. The reagents used in this test example were all commercially available chemically pure reagents. The concentration of each substance after the reaction was quantitatively analyzed by gas chromatography. The instrument used was a model 6890 gas chromatograph manufactured by Agilent company; the analytical chromatographic column used was an HP-5 capillary chromatographic column, a hydrogen flame ionization detector. The concentration of the components is quantified by an external standard method. Firstly, measuring the peak area of each component, searching the concentration of the component through a standard working curve, and calculating indexes such as selectivity of the corresponding product.
The cyclohexane conversion, cyclohexanone and cyclohexanol selectivity in the test cases were calculated according to the following formulas, respectively:
cyclohexane conversion% = (moles of cyclohexane remaining after 1-reaction/moles of cyclohexane charged before reaction) ×100%
Cyclohexanone selectivity% = moles of cyclohexanone after reaction/(moles of cyclohexane charged before reaction-moles of cyclohexane remaining after reaction) ×100%
Cyclohexanol selectivity% = moles of cyclohexanol after reaction/(moles of cyclohexane charged before reaction-moles of cyclohexane remaining after reaction) ×100%
The titanium silicon molecular sieves prepared in the examples and the comparative examples are respectively taken as catalysts, added into a three-neck flask according to the mass ratio of the catalysts to the cyclohexane to the solvent methanol of 1:20:100, and uniformly mixed under magnetic stirring. After heating to 70℃by electric heating, an aqueous hydrogen peroxide solution (30% by weight) was added to the mixture at a molar ratio of cyclohexane to hydrogen peroxide of 1:1, the reaction temperature was maintained at 70℃for 5 hours, and samples were taken for chromatographic analysis, and the reaction results are shown in Table 2.
Figure BDA0003426181160000141
Figure BDA0003426181160000151
Figure BDA0003426181160000161
As can be seen from the results in Table 3, the titanium-silicon molecular sieve of the present invention has high activity of catalyzing and oxidizing cyclohexane, and in the reaction of catalyzing and oxidizing cyclohexane, the conversion rate of cyclohexane is as high as 99%, the selectivity of cyclohexanone is as high as 48%, and the selectivity of cyclohexanol is as high as 48%.
The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, a number of simple variants of the technical solution of the invention are possible, including combinations of the individual technical features in any other suitable way, which simple variants and combinations should likewise be regarded as being disclosed by the invention, all falling within the scope of protection of the invention.

Claims (12)

1. A titanium silicalite molecular sieve is characterized in that the aperture of the titanium silicalite molecular sieve is 0.1-2nm, and the specific surface area is 440-580m 2 Per gram, a total pore volume of 0.4-0.6cm 3 /g; the external surface area is 50-200m 2 Per gram, micropore volume of 0.13-0.2cm 3 /g; the particle size of the molecular sieve particles is 100-250nm; the crystallinity of the molecular sieve is more than or equal to 50 percent.
2. The titanium silicalite molecular sieve according to claim 1, wherein the molar ratio of titanium to silicon in the titanium silicalite molecular sieve is 0.001-0.04:1, preferably 0.005-0.025;
preferably, in the infrared spectrogram of the titanium silicalite molecular sieve, the wave number is 960cm -1 The peak area and wave number of the obtained product were 800cm -1 The ratio of the peak-to-peak area is 0.4 to 1.5.
3. A method of making a titanium silicalite molecular sieve, the method comprising:
(1) Uniformly mixing a silicon source, an alkaline template agent, a titanium source, water and isopropanol to obtain titanium silicasol;
(2) Adding a compound shown in a formula (I) into the titanium silicasol, and carrying out hydrothermal crystallization and roasting on the obtained mixture;
Figure FDA0003426181150000011
wherein i is 1-6An integer; r is R 1 、R 2 And R is 3 Each independently selected from C 1 -C 6 Is a hydrocarbon group.
4. A method according to claim 3, wherein i is an integer from 1 to 5;
preferably, R 1 、R 2 And R is 3 Each independently selected from methyl, ethyl or propyl.
5. The method of claim 3 or 4, wherein the silicon source is in SiO 2 The molar ratio of the silicon source to the compound represented by formula (I) is 1: (0.01-0.3), preferably 1: (0.01-0.2).
6. The method of any of claims 3-5, wherein the silicon source is in SiO 2 Calculated by N when the alkaline template agent contains nitrogen element, and calculated by OH when the alkaline template agent does not contain nitrogen element - The titanium source is calculated as TiO 2 The meter is used for measuring the number of the wires,
the molar ratio of the silicon source to the alkaline template to the water is 1: (0.05-0.4): (5-40); preferably 1: (0.1-0.3): (5-25);
preferably, the molar ratio of the silicon source, the titanium source and isopropanol is 1: (0.001-0.04): (0.1-10), preferably 1: (0.005-0.025): (0.1-5).
7. The method of any of claims 3-6, wherein the silicon source is selected from at least one of tetramethyl silicate, tetraethyl silicate, tetrapropyl silicate, tetrabutyl silicate, white carbon black, and silica sol;
preferably, the basic template is selected from at least one of quaternary ammonium base, aliphatic amine and aliphatic alcohol amine, preferably at least one of tetramethyl ammonium hydroxide, tetraethyl ammonium hydroxide, tetrapropyl ammonium hydroxide and tetrabutyl ammonium hydroxide;
preferably, the titanium source is selected from an organic titanium source and/or an inorganic titanium source;
preferably, the titanium source is selected from at least one of titanium tetrachloride, titanium sulfate, titanium nitrate, tetraethyl titanate, tetrapropyl titanate, and tetrabutyl titanate.
8. The method according to any one of claims 3-7, wherein step (1) further comprises: stirring and mixing a silicon source, an alkaline template agent and water to obtain a mixed system; then, dropwise adding a mixed solution of a titanium source and isopropanol into the mixed system to obtain a mixed solution;
preferably, the dripping speed of the mixed solution is 0.01-0.5mL/min;
preferably, step (1) further comprises: alcohol expelling is carried out on the mixed solution;
preferably, the alcohol expelling conditions include: the temperature is 30-100 ℃ and the time is 2-10h; preferably at 40-90deg.C for 4-10 hr.
9. The method according to any one of claims 3 to 8, wherein in step (2), the conditions for hydrothermal crystallization include: heating the mixture to 50-200 ℃ within 0.1-1h, and crystallizing at 50-200 ℃ for 10-100h; preferably crystallization is carried out at a temperature of 100-200 ℃ for 20-80 hours;
preferably, the roasting conditions include: the temperature is 400-800 ℃ and the time is 1-15h.
10. A titanium silicalite molecular sieve prepared according to the method of any one of claims 3-9;
preferably, the aperture of the titanium silicalite molecular sieve is 0.1-2nm, and the specific surface area is 440-580m 2 Per gram, a total pore volume of 0.4-0.6cm 3 /g; the external surface area is 50-200m 2 Per gram, micropore volume of 0.13-0.2cm 3 /g; the particle size of the molecular sieve particles is 100-250nm; the crystallinity of the molecular sieve is more than or equal to 50%;
preferably, the molar ratio of titanium to silicon in the titanium-silicon molecular sieve is 0.001-0.04:1, preferably 0.005-0.025:1, a step of;
preferably, in the infrared spectrogram of the titanium silicalite molecular sieve, the wave number is 960cm -1 The peak area and wave number of the obtained product were 800cm -1 The ratio of the peak-to-peak area is 0.4 to 1.5.
11. A method of catalytically oxidizing cycloalkanes, the method comprising: contacting a cycloalkane with a peroxide in the presence of a catalyst to react, wherein the catalyst comprises the titanium silicalite molecular sieve of claim 1, 2 or 10;
preferably, the cycloalkane is selected from C 3 -C 15 Is preferably C 4 -C 8 Is a cycloalkane of (2);
preferably, the cycloalkane is selected from at least one of cyclohexane, cyclopentane and methylcyclohexane;
preferably, the peroxide is selected from at least one of t-butyl hydroperoxide, cyclohexyl hydroperoxide, isopropyl hydroperoxide, cumene hydroperoxide, hydrogen peroxide, sodium percarbonate and sodium perborate.
12. The method of claim 11, wherein the reaction conditions comprise: the weight ratio of the catalyst to the cycloalkane is 1: (1-20); the molar ratio of cycloalkane to peroxide is 1: (0.1-10);
preferably, the reaction conditions include: the temperature is 40-100deg.C, and the time is 1-8h.
CN202111578457.7A 2021-12-22 2021-12-22 Titanium silicon molecular sieve, preparation method thereof and method for catalytic oxidation of cycloalkane Pending CN116332198A (en)

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