Titanium species, titanium silicon molecular sieve catalyst, and preparation method and application thereof

Abstract

The present invention provides a titanium species, a titanium silicon molecular sieve catalyst, and a preparation method and application thereof. Based on the preparation method of the present invention, the TS-1 catalyst is modified, and the catalytic performance of the unmodified TS-1 catalyst is greatly improved, especially the catalytic performance in the epoxidation of propylene to propylene oxide. The titanium species has the expression Ti(OH) x (OSi) y , wherein x is 2 and y is 3, or x is 4 and y is 2; when the titanium species is a five-coordinate titanium species with x being 2 and y being 3, its ultraviolet resonance Raman spectrum has 510cm ‑1 、685cm ‑1 and 1125cm ‑1 When the titanium species is a hexacoordinated titanium species with x being 4 and y being 2, its ultraviolet resonance Raman spectrum has a peak of 441 cm ‑1 、705cm ‑1 、1125cm ‑1 and 1342cm ‑1 Raman peaks.

Description

Technical Field

[0001] The present invention relates to a new titanium species, a titanium silicon molecular sieve catalyst, and a preparation method and application thereof. Background Art

[0002] The introduction of titanium silicalite TS-1 marked a milestone in molecular sieve catalysis. It is a molecular sieve with an MFI topology, in which some of the silicon atoms in the framework are replaced by titanium atoms. TS-1 is an environmentally friendly catalyst. Its catalytic system, combined with aqueous hydrogen peroxide, enables green processes for many oxidation reactions, such as olefin epoxidation, ketone ammoximation, aromatic hydrocarbon hydroxylation, and the oxidation of alkanes and alcohols. Propylene epoxidation, cyclohexanone ammoximation, butanone ammoximation, and phenol hydroxylation have been successfully commercialized using TS-1 as a catalyst.

[0003] The existence state of titanium in TS-1 (titanium species) is the fundamental factor that determines its catalytic activity. Currently, the titanium species in TS-1 include four-coordinate skeleton titanium "TiO4" (Ti(OSi)4), four-coordinate binuclear titanium species, six-coordinate titanium " TiO6 ” , anatase TiO2, amorphous Ti-O-Ti, etc. "TiO4" has catalytic activity for all of the above reactions, four-coordinated binuclear titanium species, six-coordinated titanium " TiO6 ” It is an active titanium species in the epoxidation of propylene to produce propylene oxide. Anatase TiO2 has no effect on the reaction, while Ti-O-Ti is harmful to the reaction.

[0004] After decades of research, TS-1 has become a highly effective industrial catalyst. Despite diverse preparation methods, tetracoordinate titanium species, particularly TiO₄, are considered the most active titanium species in industrial catalysts. However, their low catalytic activity limits their performance and application. Therefore, the development of novel active titanium species is needed to significantly enhance the catalytic performance of TS-1.

[0005] Hydrothermal modification of TS-1 is an important method for regulating the presence of titanium species and improving catalyst performance. Hydrothermal modification of TS-1 refers to mixing the calcined TS-1 with a certain amount of modifying liquid and then subjecting the mixture to hydrothermal post-treatment, followed by cooling and separation. The solid-phase product is dried and roasted to obtain the modified catalyst. The modifying liquid can be an alkaline solution containing organic amines (ammonium), or an inorganic base solution, or a mixed solution of organic and inorganic bases, or other solutions containing silicon or titanium elements. For example, TS-1 is mixed evenly with an aqueous solution of tetrapropylammonium hydroxide (TPAOH), and then the mixture is hydrothermally treated. The obtained product is cooled, separated, and washed, and the solid-phase product is dried and roasted to obtain the modified TS-1 catalyst. In addition to aqueous solutions of organic bases such as TPAOH, aqueous solutions of inorganic bases such as sodium hydroxide, potassium hydroxide, and ammonia can also be used for hydrothermal modification of TS-1. In addition, alkaline aqueous solutions containing silicon or titanium elements can also be used for hydrothermal modification of TS-1. The characteristic of this method is that the titanium source or silicon source must be hydrolyzed first, and then the hydrolyzed solution is used as the modification liquid.

[0006] However, the existing hydrothermal modification technology only converts "TiO4" into low-activity four-coordinated TiOH(OSi)3 or (and) " TiO6 ” , as well as titanium species that are not beneficial to the reaction, resulting in only limited improvement in catalytic performance. Therefore, how to formulate modification fluids and optimize existing hydrothermal modification technologies to create new highly catalytically active titanium species and significantly improve the catalytic performance of catalysts remains an urgent problem to be solved.

[0007] Existing hydrothermal modification technology makes it difficult to prepare titanium species with higher catalytic activity, resulting in difficulty in further improving the catalytic performance of the catalyst, limiting the further industrial application of the TS-1 catalyst. Summary of the Invention

[0008] In light of this, the present invention provides a novel titanium species, a titanium silicate molecular sieve catalyst, and its preparation method and application. Based on the preparation method of the titanium silicate molecular sieve catalyst provided by the present invention, the unmodified TS-1 catalyst is modified, significantly improving its catalytic performance, particularly in the epoxidation of propylene to produce propylene oxide.

[0009] To achieve its purpose, the present invention provides the following technical solutions:

[0010] One aspect of the present invention provides a titanium species having the expression Ti(OH) x (OSi) y, wherein x is 2 and y is 3, or x is 4 and y is 2; when the titanium species is a five-coordinate titanium species with x being 2 and y being 3, it has a wavelength of 510 cm in the ultraviolet resonance Raman spectrum excited at 257 nm or 266 nm. -1 、685cm -1 and 1125cm -1 The Raman spectrum peak has an absorption peak of 225nm in its ultraviolet-visible diffuse reflectance spectrum; when the titanium species is a hexacoordinate titanium species with an x ​​value of 4 and a y value of 2, it has an absorption peak of 441cm in the ultraviolet resonance Raman spectrum excited at 257nm or 266nm. -1 、705cm -1 、1125cm -1 and 1342cm -1 The Raman peak of the UV-visible diffuse reflectance spectrum has an absorption peak at 271 nm. The position error of the above Raman peaks is within ±5 cm. -1 The position error of the above absorption peaks is within ±5nm.

[0011] The present invention also provides a titanium silicon molecular sieve catalyst, which includes a five-coordinate titanium species expressed as Ti(OH)2(OSi)3 and / or a six-coordinate titanium species expressed as Ti(OH)4(OSi)2;

[0012] When the titanium silicate molecular sieve catalyst contains the five-coordinated titanium species but does not contain the six-coordinated titanium species, the titanium silicate molecular sieve catalyst has a wavelength of 510 cm-1 in the ultraviolet resonance Raman spectrum excited at 257 nm or 266 nm. -1 、685cm -1 and 1125cm -1 The Raman spectrum peak of the UV-visible diffuse reflectance spectrum has an absorption peak at 225nm;

[0013] When the titanium silicate molecular sieve catalyst contains both the five-coordinated titanium species and the six-coordinated titanium species, the titanium silicate molecular sieve catalyst has a wavelength of 441 cm-1 in the ultraviolet resonance Raman spectrum excited at 257 nm or 266 nm. -1 、705cm -1 、1125cm -1 and 1342cm -1 The Raman spectrum peak of the UV-visible diffuse reflectance spectrum has absorption peaks at 225nm and 271nm;

[0014] When the titanium silicate molecular sieve catalyst contains the hexacoordinated titanium species but does not contain the pentacoordinated titanium species, the titanium silicate molecular sieve catalyst has a wavelength of 441 cm-1 in the ultraviolet resonance Raman spectrum excited at 257 nm or 266 nm. -1、705cm -1 、1125cm -1 and 1342cm -1 The Raman spectrum peak of the UV-visible diffuse reflectance spectrum has an absorption peak at 271nm;

[0015] The position error of the above Raman peaks is ±5cm -1 The position error of the above absorption peaks is within ±5nm;

[0016] In the titanium silicalite catalyst, the molar ratio of the pentacoordinate titanium species expressed as Ti(OH)2(OSi)3 and the hexacoordinate titanium species expressed as Ti(OH)4(OSi)2 is 1:0-10, preferably 1:1-3; preferably, based on the amount of substance, the sum of the amount of the pentacoordinate titanium species and the hexacoordinate titanium species accounts for 0.1%-5% of the amount of the catalyst substance.

[0017] The present invention also provides a method for preparing the titanium silicate catalyst as described above, the method comprising the following steps:

[0018] 1) obtaining unmodified TS-1 molecular sieve;

[0019] 2) preparing a modified liquid; the raw materials for preparing the modified liquid include at least one of ammonium carbonate and tetrapropylammonium hydroxide; preferably include ammonium carbonate and tetrapropylammonium hydroxide, and optionally include auxiliary raw materials, the auxiliary raw materials being selected from one or more of tetraethyl orthosilicate, tetrabutyl titanate, isopropyl alcohol, and ethanol; preferably, the modified liquid is subjected to hydrothermal pretreatment;

[0020] 3) mixing the modified liquid with the unmodified TS-1 molecular sieve and performing hydrothermal treatment, and then drying and calcining the resulting solid phase product to obtain the titanium silicalite molecular sieve catalyst;

[0021] Preferably, in step 3), the amount of the modification liquid is 1 to 100 mL relative to 1 g of the unmodified TS-1 molecular sieve; the temperature and time of the hydrothermal treatment are 100 to 250° C. and 1 to 120 h, respectively;

[0022] Preferably, in step 3), the calcination is performed at 400-600° C. for 4-12 hours.

[0023] In one embodiment, in step 2), ammonium carbonate is prepared into an aqueous ammonium carbonate solution, which is then subjected to hydrothermal pretreatment and used as a modification liquid, or is directly used as a modification liquid without hydrothermal pretreatment;

[0024] Preferably, the concentration of the aqueous ammonium carbonate solution is 0.05 mol / L-5 mol / L;

[0025] Preferably, the hydrothermal pretreatment is a hydrothermal treatment at 100-250° C. for 1-120 h;

[0026] Preferably, when the ammonium carbonate aqueous solution is used as a modifying liquid after the hydrothermal pretreatment, in step 3), the hydrothermal treatment is carried out at 100-250°C for 1-120 hours. By adopting this scheme, a molecular sieve catalyst containing both the pentacoordinate titanium species and the hexacoordinate titanium species can be obtained by hydrothermally pretreating the ammonium carbonate aqueous solution; when the ammonium carbonate aqueous solution is directly used as a modifying liquid without hydrothermal pretreatment, in step 3), the hydrothermal treatment is carried out at 150-200°C for 1-120 hours. By adopting this scheme, a molecular sieve catalyst containing the hexacoordinate titanium species can be obtained.

[0027] In another embodiment, in step 2), the tetrapropylammonium hydroxide is prepared into a 0.06-1.2 mol / L tetrapropylammonium hydroxide aqueous solution, without the need for the hydrothermal pretreatment, and ammonium carbonate is optionally added thereto and used directly as a modifying liquid; in step 3), the hydrothermal treatment is carried out at 150-220°C for 1 to 120 hours, preferably at 199-220°C for 1 to 120 hours (the inventors have found that at this preferred temperature, products containing the pentacoordinate titanium species and the hexacoordinate titanium species can be easily obtained simultaneously, and the resulting catalyst has better catalytic performance; if the hydrothermal treatment temperature is lower than this preferred temperature range, a molecular sieve catalyst containing the pentacoordinate titanium species is more likely to be obtained). In this case, the molar ratio of ammonium carbonate to tetrapropylammonium hydroxide is 0-2:1.

[0028] In a preferred embodiment, in step 2), tetrapropylammonium hydroxide and the optional auxiliary raw materials are mixed in water and heated at 25-60°C for 0.5-12 hours; then ammonium carbonate is added and hydrothermally pretreated at 100-250°C for 1-120 hours to obtain a modified solution; using this solution, a molecular sieve catalyst containing both the penta-coordinated titanium species and the hexa-coordinated titanium species can be obtained;

[0029] The auxiliary raw materials are selected from one or more of ethyl orthosilicate, tetrabutyl titanate, isopropyl alcohol, and ethanol, wherein the molar ratio of ethyl orthosilicate to tetrapropylammonium hydroxide is 0-4.5:1, preferably 0.1-3.5:1; the molar ratio of tetrabutyl titanate to tetrapropylammonium hydroxide is 0-0.1:1, preferably 0.005-0.07:1; the molar ratio of isopropyl alcohol to tetrapropylammonium hydroxide is 0-15:1, preferably 0.1-13.5:1; the molar ratio of ethanol to tetrapropylammonium hydroxide is 0-20:1, preferably 0.1-15:1; when the auxiliary raw materials in step 2) include ethyl orthosilicate and / or tetrabutyl titanate, the modified liquid is a liquid phase obtained by solid-liquid separation of the mixture obtained by the hydrothermal pretreatment;

[0030] The molar ratio of the tetrapropylammonium hydroxide to water is 1:10-300, and the molar ratio of the tetrapropylammonium hydroxide to the ammonium carbonate is 1:0.1-1;

[0031] Preferably, after the heating treatment and before the addition of ammonium carbonate, the following operation is further included: heating to 85-95°C to evaporate to 1 / 3-1 / 2 of the volume before heating, and then adding water to 0.7-3 times the volume before heating.

[0032] In another embodiment, in step 2), tetrapropylammonium hydroxide and the optional auxiliary raw materials are mixed in water and heated at 25-60° C. for 0.5-12 hours to obtain solution I;

[0033] Mixing another portion of tetrapropylammonium hydroxide and optionally another portion of the auxiliary raw material in water to obtain a solution II;

[0034] After mixing solution II with solution I, ammonium carbonate is added, and hydrothermal pretreatment is performed at 100-250° C. for 1-120 hours to obtain a modified solution. By adopting this scheme, a molecular sieve catalyst containing both the penta-coordinated titanium species and the hexa-coordinated titanium species can be obtained;

[0035] Preferably, after solution II is mixed with solution I, before adding the ammonium carbonate, the temperature is raised to 85-95°C to evaporate to 1 / 3-1 / 2 of the volume before heating, and then water is added to 0.7-3 times the volume before heating;

[0036] Wherein, in solution I, the auxiliary raw material is selected from one or both of tetraethyl orthosilicate and / or ethanol, the molar ratio of the tetrapropylammonium hydroxide to the tetraethyl orthosilicate is 1:0-4.5, preferably 1:0.1-3.50; the molar ratio of the tetrapropylammonium hydroxide to the ethanol is 1:0-20, preferably 1:0.1-15; the molar ratio of the tetrapropylammonium hydroxide to water is 1:10-100;

[0037] In solution II, the auxiliary raw material is selected from tetrabutyl titanate and / or isopropyl alcohol, the molar ratio of tetrapropylammonium hydroxide to tetrabutyl titanate is 1:0-0.4, preferably 1:0.005-0.3; the molar ratio of tetrapropylammonium hydroxide to isopropyl alcohol is 1:0-15, preferably 1:0.1-13.5; the molar ratio of tetrapropylammonium hydroxide to water is 1:10-250;

[0038] When the auxiliary raw material in step 2) includes ethyl orthosilicate and / or tetrabutyl titanate, the modified liquid is a liquid phase obtained by solid-liquid separation of the mixture obtained by the hydrothermal pretreatment;

[0039] The volume ratio of solution I to solution II is 1:0.16-1.2, and the molar ratio of the total amount of tetrapropylammonium hydroxide to the amount of ammonium carbonate is 1:0.1-1. When preparing the modified solution in this manner, ammonium carbonate must be added before the hydrothermal pretreatment, and the hydrothermal pretreatment must be performed. By adding ammonium carbonate and performing the hydrothermal pretreatment, the target product can be subsequently obtained by hydrothermal treatment at a relatively low temperature (e.g., 170°C, for example, 100°C-180°C).

[0040] Preferably, the unmodified TS-1 molecular sieve is prepared according to the following steps:

[0041] 1.1) mixing ethyl orthosilicate and tetrapropylammonium hydroxide in water and hydrolyzing them to obtain solution A; wherein the molar ratio of ethyl orthosilicate, tetrapropylammonium hydroxide, and water is 0.1-4.5:1:20-60; and the hydrolysis is carried out at 25-60° C.;

[0042] 1.2) Mixing isopropyl alcohol and tetrabutyl titanate, stirring at 10-30° C. for 0.25-1.5 h, and then adding tetrapropylammonium hydroxide aqueous solution to obtain solution B; wherein the molar ratio of tetrabutyl titanate, isopropyl alcohol, tetrapropylammonium hydroxide, and water in solution B is 0.05-0.4:0.5-13.5:1:10-160;

[0043] 1.3) Solution A and Solution B are mixed in a volume ratio of 1:0.16-1.2, and ammonium carbonate is added to form Solution C, wherein the ratio of ammonium carbonate to the total molar amount of tetrapropylammonium hydroxide used in steps 1.1) and 1.2) is 0.1-1:1; preferably, after mixing Solution A and Solution B, alcohol is evaporated at 80-95° C. before adding the ammonium carbonate, and the ratio of the volume after evaporation to the volume before evaporation is 1 / 3-1 / 2, and then water is added to 0.7-3 times the volume before evaporation;

[0044] 1.4) Solution C is hydrothermally treated at 100-250° C. for 1-120 h, cooled, and separated to obtain a solid phase product and a liquid phase product. The solid phase product is dried and calcined at 400-600° C. for 4-12 h to obtain the unmodified TS-1 molecular sieve.

[0045] In one embodiment, the liquid phase product obtained when preparing the unmodified TS-1 molecular sieve is directly used as the modified liquid in step 3). Using this solution, a molecular sieve catalyst containing both the pentacoordinate titanium species and the hexacoordinate titanium species can be obtained.

[0046] Based on the above preparation method, the prepared molecular sieve catalyst contains a penta-coordinate titanium species expressed as Ti(OH)2(OSi)3 and / or a hexa-coordinate titanium species expressed as Ti(OH)4(OSi)2. In some embodiments, the molar ratio of the penta-coordinate titanium species expressed as Ti(OH)2(OSi)3 to the hexa-coordinate titanium species expressed as Ti(OH)4(OSi)2 is 1:0-10, preferably 1:1-3. Products with different molar ratios can be obtained by adjusting the amount of tetrapropylammonium hydroxide, the amount of ammonium carbonate, the reaction temperature, time, etc.

[0047] The present invention also provides an application, wherein the titanium species described above, the titanium silicate catalyst described above, or the titanium silicate prepared by the preparation method described above is used as a catalyst in olefin epoxidation, ketone ammoximation, aromatic hydrocarbon hydroxylation, and oxidation of alkanes and alcohols.

[0048] The technical solution provided by the present invention has the following beneficial effects:

[0049] Based on the preparation method of the present invention, a titanium silicate molecular sieve catalyst containing new pentacoordinate titanium species and / or hexacoordinate titanium species can be obtained, which can greatly improve the catalytic performance of the unmodified TS-1 catalyst, especially the catalytic performance in the epoxidation of propylene to produce propylene oxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 The structure and ultraviolet resonance Raman spectrum of pentacoordinate titanium species Ti(OH)2(OSi)3 in one embodiment are shown;

[0051] Figure 2 The structure and ultraviolet resonance Raman spectrum of hexacoordinated titanium species Ti(OH)4(OSi)2 in one embodiment are shown;

[0052] Figure 3 is a UV-visible diffuse reflectance spectrum of the catalyst in one embodiment;

[0053] Figure 4The figure is a UV-visible diffuse reflectance spectrum after peak separation processing in one embodiment. DETAILED DESCRIPTION

[0054] To facilitate understanding of the present invention, the present invention will be described more fully below with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the accompanying drawings. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the disclosure of the present invention.

[0055] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one skilled in the art to which this invention belongs. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. "Optionally" means containing or not containing, adding or not adding, and similar meanings.

[0056] Any matters not specifically explained in this document are understood or known by those skilled in the art based on the existing technology, conventional technical means or common knowledge, and are not elaborated on here.

[0057] Example 1

[0058] 1) Prepare unmodified TS-1 molecular sieve, the preparation steps are as follows:

[0059] 1.1) In a 250-mL three-necked flask, add 35.5 mL of tetrapropylammonium hydroxide (TPAOH), 40.5 mL of 1.2 mol / L TPAOH, and 12 mL of deionized water. Stir at 40°C for 5 h to form Solution A. The molar ratio of tetrapropylammonium hydroxide (TPAOH), tetrapropylammonium hydroxide, and water is 1:3.27:47.

[0060] 1.2) Add 0.90 mL of tetrabutyl titanate to 12.5 mL of isopropyl alcohol and stir at room temperature for 30 min. Then, add 11.5 mL of a 1.2 mol / L aqueous solution of TPAOH and 26.5 mL of deionized water to form Solution B. The molar ratio of tetrapropylammonium hydroxide, tetrabutyl titanate, isopropyl alcohol, and water is 1:0.188:11.83:142.

[0061] 1.3) Solution B is added to Solution A, then the temperature is raised to 95°C and the alcohol is evaporated to 60 mL. The solution is then filled with water to 100 mL. Finally, 40 mL of an aqueous solution containing 2.28 g of ammonium carbonate is added to form Solution C. The molar ratio of the total molar amount of tetrapropylammonium hydroxide used in steps 1.1) and 1.2) to the molar ratio of the ammonium carbonate and water used in step 1.3) is 1:0.23:110.

[0062] 1.4) Solution C was hydroheated at 170°C for 72 hours and then cooled to room temperature. The resulting product was separated, and the liquid phase was collected for later use. The solid phase was dried at 100°C for 12 hours and calcined at 540°C for 6 hours to obtain the unmodified m-TS-1 catalyst (i.e., unmodified TS-1 molecular sieve).

[0063] 2) Prepare a 0.06 mol / L tetrapropylammonium hydroxide aqueous solution and use it directly as a modification solution;

[0064] 3) The modified solution was added to a reactor at a ratio of 1 g m-TS-1 to 10 mL of 0.06 mol / L tetrapropylammonium hydroxide aqueous solution, stirred evenly, and then hydrothermally treated at 170°C for 72 h. The hydrothermal product was cooled and separated, and the solid phase product was dried at 100°C for 12 h and then calcined at 540°C for 6 h to obtain the hydrothermally modified TS-1 catalyst, which was labeled T 170 -TS-1.

[0065] After testing, T 170 -TS-1 contains Ti(OH)(OSi)3, Ti(OH)2(OSi)3 and anatase TiO2 at a molar ratio of 1.11:1:0.80. Since the mass fraction of SiO2 in TS-1 is more than 98%, it can be considered that the molar mass of TS-1 is consistent with that of SiO2, both of which are 60 g / mol; therefore, for this embodiment, 170 The molar content of pentacoordinated titanium species in the catalyst of TS-1 was calculated as follows: 170 -TS-1, its amount of substance is 1 / 60 = 1.67 × 10 -2 mol; it is calculated that, based on the amount of substance, the amount of Ti(OH)2(OSi)3 in the catalyst accounts for 0.50% of the amount of the catalyst substance; the percentages of the amount of the pentacoordinate titanium species and the hexacoordinate titanium species in the catalyst in the following examples are calculated with reference to this method.

[0066] Example 2

[0067] The liquid product obtained in step 1.4) of Example 1 was used as the modifying solution. The modified solution was then added to a reactor at a ratio of 1 g m-TS-1 to 13.6 mL of the modifying solution, stirred evenly, and then hydrothermally treated at 170°C for 72 hours. The hydrothermal product was cooled and separated, and the solid product was dried at 100°C for 12 hours and calcined at 540°C for 6 hours to obtain the hydrothermally modified TS-1 catalyst, labeled ML-TS-1.

[0068] After testing, it was found that Ti(OH)(OSi)3, Ti(OH)2(OSi)3, Ti(OH)4(OSi)2 and anatase TiO2 were simultaneously present in ML-TS-1, among which the molar ratio of Ti(OH)2(OSi)3 and Ti(OH)4(OSi)2 was 1:1.27. Calculated by the amount of substance, the sum of the amounts of the two substances accounted for 0.86% of the amount of the catalyst substance.

[0069] Characterization and analysis of titanium species in catalysts:

[0070] I) Using different excitation light wavelengths (λ ex ) was used to qualitatively analyze the titanium species in the catalyst sample with a spectral resolution of 2 cm -1 244nm excitation light (λ ex =244nm) was generated by intracavity frequency doubled (FSH) of a 488nm laser (laser source model and manufacturer: Lexel laser, Lexel Inc.). The laser power when irradiating the sample was approximately 3mV. The 257nm excitation light was generated by intracavity frequency doubled (FSH) of a 514nm visible light (laser source model and manufacturer: Model NPL-N-257, Changchun New Industries Optoelectronics Technology Co., Ltd.). The laser power when irradiating the sample was 3mV. The 266nm excitation light was generated by intracavity frequency doubled (FSH) of a 532nm visible light (laser source model and manufacturer: DPSS 532 Model 200, Coherent Inc.). The laser power when irradiating the sample was 3mV. The 325nm excitation light was provided by a He:Cd laser source with an output power of 30mV. The laser power when irradiating the sample was 3mV.

[0071] Ultraviolet-visible diffuse reflectance spectroscopy was used to qualitatively analyze the titanium species in the catalyst samples. The instrument used was a Jasco UV-550 spectrophotometer with a detection wavelength range of 190 to 500 nm. BaSO4 was used as a reference during the detection process.

[0072] The structure of the new titanium species was elucidated through theoretical calculations. The Gaussian 09 software package was used to optimize the titanium species structure and calculate the associated frequencies. Energy calculations and structural optimization were performed using the B3LYP functional and the 6-311G(d,p) basis set for H, C, O, Si, and Ti atoms. All configurational optimizations were performed under unconstrained conditions. Van der Waals interactions were described using the Grimme DFT-D3 method, and the molecular sieve was structurally modeled using a cluster model. The initial structure of the cluster model was derived from crystal phase data of the ZSM-5 molecular sieve, where the Ti atom is generally assumed to reside at the T7 position within the ZSM-5 framework.

[0073] The total titanium content in each sample was determined by a PerkinElmer OPTIMA 2000 DV inductively coupled plasma spectrometer.

[0074] II) Take m-TS-1 as an example to illustrate UV resonance Raman spectroscopy detection:

[0075] 0.05g of m-TS-1 powder was squeezed into sheets, and ultraviolet resonance Raman spectroscopy with excitation light wavelengths of 244nm, 257nm, 266nm and 325nm was used to detect the titanium species in the molecular sieve, which was only tetracoordinate skeleton titanium "TiO4" (Ti(OSi)4).

[0076] T 170 -TS-1 is used as an example to illustrate its UV resonance Raman spectroscopy and UV-visible diffuse reflectance spectroscopy detection:

[0077] 0.05g T 170 -TS-1 powder was extruded into tablets and detected by ultraviolet resonance Raman spectroscopy at excitation wavelengths of 244nm, 257nm, 266nm and 325nm. The results showed that when λ ex =244nm, 490 and 1125cm in the spectrum -1 The Raman peaks indicate that T 170 -TS-1 contains titanium species Ti(OH)(OSi)3; when λ ex =257nm or 266nm, 510cm appears in the spectrum -1 、685cm -1 and 1125cm -1 The Raman peak of T 170 -TS-1 has a new five-coordinated titanium species Ti(OH)2(OSi)3( Figure 1 ), the absorption peak position in its UV-visible diffuse reflectance spectrum is 220-230nm; when λ ex =325nm, 144cm in the spectrum -1 、390cm -1 , 515cm -1 and 637cm -1 The Raman peaks indicate that T 170 -TS-1 has anatase TiO2. In summary, T 170 -TS-1 contains Ti(OH)(OSi)3, Ti(OH)2(OSi)3 and anatase TiO2.

[0078] III) Taking ML-TS-1 as an example, the content of each titanium species in ML-TS-1 is detected by combining ultraviolet resonance Raman spectroscopy (UV-Raman), theoretical calculation (DFT), ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis) and plasma emission spectroscopy (ICP). The specific steps are as follows:

[0079] III.1) Before testing, 0.0540 g of ML-TS-1 was dissolved in 1 mL of concentrated hydrochloric acid (12 mol / L) and 1 mL of concentrated hydrofluoric acid (33.3 mol / L). 3 mL of the solution was diluted in a 100 mL plastic volumetric flask and used for testing. The total titanium content (Ti) in each gram of ML-TS-1 was determined by inductively coupled plasma spectrometry. Total ) is 24.57×10 -5 mol.

[0080] III.2) Qualitative analysis of each titanium species in ML-TS-1. 0.05g of ML-TS-1 powder was squeezed into a sheet and tested using a UV Raman spectrometer. The results showed that when λ ex =244nm, 490 and 1125cm in the spectrum -1 The Raman peaks of ML-TS-1 showed that titanium species Ti(OH)(OSi)3 existed. ex = 257nm or 266nm, 441cm appears in the spectrum -1 、705cm -1 、1125cm -1 and 1342cm -1 The Raman peaks of ML-TS-1, combined with theoretical calculations, indicate that there is a new hexacoordinated titanium species Ti(OH)4(OSi)2( Figure 2 ); when λ ex =325nm, 144cm in the spectrum -1 、390cm -1 , 515cm -1 and 637cm -1 The Raman peaks indicate the presence of anatase TiO2 in ML-TS-1.

[0081] Since there are both hexacoordinated titanium species Ti(OH)4(OSi)2 and pentacoordinated titanium species Ti(OH)2(OSi)3 in ML-TS-1, exWhen UV Raman spectroscopy was performed at 257 nm or 266 nm, it was found that the Raman peak signal of the pentacoordinate titanium species was covered by the Raman peak signal of the hexacoordinate titanium species. Therefore, UV-visible diffuse reflectance spectroscopy was used to characterize the presence of the pentacoordinate titanium species. The UV-visible diffuse reflectance spectrum of ML-TS-1 showed an absorption peak at 225 nm, indicating that it contains the new type of Ti(OH)2(OSi)3. In summary, ML-TS-1 contains Ti(OH)(OSi)3, Ti(OH)2(OSi)3, Ti(OH)4(OSi)2, and anatase TiO2.

[0082] III.3) Quantitative analysis of each titanium species in ML-TS-1. Based on the results of step III.2), the UV-visible diffuse reflectance spectrum of ML-TS-1 ( Figure 3 ) for peak separation (see the spectrum after peak separation) Figure 4 ). Determine the position and peak height of each peak after peak separation, and ensure that the number of separated peaks is consistent with the number of titanium species. The peak separation results show that the spectrum has absorption peaks at 213nm, 225nm, 271nm and 311nm, which are attributed to Ti(OH)(OSi)3, Ti(OH)2(OSi)3, Ti(OH)4(OSi)2 and anastase TiO2, respectively. Use Origin integration to calculate the peak area of ​​each peak obtained. But it should be noted that only the right half of the data of each peak is used during integration. This is because the UV-Vis instrument can only collect spectrum to 190nm, and the spectrum line suddenly cuts off at 190nm, resulting in the peak around 210nm having no left half. Calculate the sum of the integrated peak areas ∑A of all peaks in each catalyst spectrum i The specific content of each titanium species in the catalyst was calculated by the following formula.

[0083] n i (Ti)=(A i (Ti) / ∑A i (Ti))×Ti Total

[0084] Based on the above analysis, the contents of Ti(OH)(OSi)3, Ti(OH)2(OSi)3, Ti(OH)4(OSi)2 and anatase TiO2 in each gram of ML-TS-1 catalyst are 6.33×10 -5 mol, 6.06×10 -5 mol, 7.71×10 -5 mol and 4.47×10 -5In the obtained catalyst ML-TS-1, the molar ratio of the penta-coordinated titanium species Ti(OH)2(OSi)3 to the hexa-coordinated titanium species Ti(OH)4(OSi)2 is 1:1.27. The sum of the two species accounts for 0.86% of the catalyst species.

[0085] The types and contents of titanium species in the titanium silicate molecular sieves of the other examples were analyzed by referring to the above method.

[0086] Example 3

[0087] The m-TS-1 catalyst prepared in Example 1 was used as the unmodified TS-1 molecular sieve.

[0088] Mix 52 mL of a 1.2 mol / L TPAOH aqueous solution with 40 mL of deionized water, stir, and heat at 40°C for 5 h. Then, heat to 95°C and distill the solution to 46 mL, which was then refilled with water to 100 mL. Finally, add 40 mL of an aqueous solution containing 2.28 g of ammonium carbonate to form Solution D. The molar ratio of tetrapropylammonium hydroxide, ammonium carbonate, and water is 1:0.23:110. Solution D is hydrothermally pretreated at 170°C for 72 h and then cooled to room temperature to obtain a modified solution.

[0089] The modified solution was added to the reactor at a ratio of 1 g m-TS-1 to 13.5 mL of liquid and stirred evenly. The mixture was then hydrothermally treated at 170°C for 72 h. The hydrothermal product was cooled and separated, and the solid phase product was dried at 100°C for 12 h and then calcined at 540°C for 6 h to obtain the hydrothermally modified TS-1 catalyst. The sample was labeled T * -TS-1.

[0090] The obtained catalyst T * -TS-1 contains Ti(OH)(OSi)3, Ti(OH)2(OSi)3, Ti(OH)4(OSi)2 and anatase TiO2 at the same time, with the molar ratio of each species being 1.05:1:1.38:0.74. The molar ratio of the pentacoordinated titanium species Ti(OH)2(OSi)3 and the hexacoordinated titanium species Ti(OH)4(OSi)2 is 1:1.38. Calculated by the amount of substance, the sum of the two amounts accounts for 0.82% of the amount of the catalyst substance.

[0091] Example 4

[0092] The m-TS-1 catalyst prepared in Example 1 was used as the unmodified TS-1 molecular sieve.

[0093] 35.5 mL of tetraethyl orthosilicate, 52 mL of TPAOH (1.2 mol / L), and 40 mL of deionized water were mixed and heated at 40°C for 5 h with stirring for hydrolysis. The mixture was then heated to 95°C to distill the remaining volume to 60 mL, which was then refilled with water to 100 mL. Finally, 40 mL of an aqueous solution containing 2.28 g of ammonium carbonate was added to form Solution E. The molar ratio of tetrapropylammonium hydroxide, tetraethyl orthosilicate, ammonium carbonate, and water was 1:2.55:0.23:110. Solution E was hydrothermally pretreated at 170°C for 72 h, then cooled to room temperature. The resulting product was separated and used as the modified solution.

[0094] The modified solution was added to a reactor at a ratio of 1 g m-TS-1 to 13.5 mL of liquid and stirred thoroughly. The catalyst was then hydrothermally treated at 170°C for 72 hours. The hydrothermal product was cooled and separated, and the solid phase was dried at 100°C for 12 hours and calcined at 540°C for 6 hours to obtain the hydrothermally modified TS-1 catalyst, designated Si-TS-1.

[0095] The obtained catalyst Si-TS-1 contains Ti(OH)(OSi)3, Ti(OH)2(OSi)3, Ti(OH)4(OSi)2 and anatase TiO2 at the same time, and the molar ratio of each species is 1.13:1:1.12:0.66, among which the molar ratio of Ti(OH)2(OSi)3 pentacoordinate titanium species and Ti(OH)4(OSi)2 hexacoordinate titanium species is 1:1.12. Calculated by the amount of substance, the sum of the amounts of the two substances accounts for 0.79% of the amount of the catalyst substance.

[0096] Example 5

[0097] The m-TS-1 catalyst prepared in Example 1 was used as the unmodified TS-1 molecular sieve.

[0098] Mix 38.0 mL of ethanol, 52 mL of TPAOH (1.2 mol / L), and 40 mL of deionized water and stir at 40°C for 5 hours. The molar ratio of tetrapropylammonium hydroxide, ethanol, and water is 1:10.43:110. Then, heat the mixture to 95°C and evaporate the alcohol to 60 mL, then add water to 100 mL. Finally, add 40 mL of an aqueous solution containing 2.28 g of ammonium carbonate to form Solution F. The molar ratio of tetrapropylammonium hydroxide to ammonium carbonate is 1:0.23. Solution F is hydrothermally pretreated at 170°C for 72 hours and then cooled to room temperature to obtain a modified solution.

[0099] The modified solution was added to a reactor at a ratio of 1 g m-TS-1 to 13.5 mL of liquid and stirred thoroughly. The mixture was then hydrothermally treated at 170°C for 72 hours. The hydrothermal product was cooled, separated, and the solid phase was dried at 100°C for 12 hours and calcined at 540°C for 6 hours to obtain the hydrothermally modified TS-1 catalyst, designated A-TS-1.

[0100] In the obtained catalyst A-TS-1, Ti(OH)(OSi)3, Ti(OH)2(OSi)3, Ti(OH)4(OSi)2 and anatase-type TiO2 are present at the same time, and the molar ratio of each species is 1.06:1:1.42:0.76, among which the molar ratio of Ti(OH)2(OSi)3 pentacoordinate titanium species and Ti(OH)4(OSi)2 hexacoordinate titanium species is 1:1.42. In terms of the amount of substance, the sum of the amounts of the two substances accounts for 0.84% ​​of the amount of the catalyst substance.

[0101] Example 6

[0102] The m-TS-1 catalyst prepared in Example 1 was used as the unmodified TS-1 molecular sieve.

[0103] 38.0 mL of ethanol, 40.5 mL of TPAOH (1.2 mol / L), and 12 mL of deionized water were mixed and heated at 40°C for 5 h with stirring for hydrolysis to form Solution I. The molar ratio of tetrapropylammonium hydroxide, ethanol, and water was 1:13.39:46.42. 0.90 mL of tetrabutyl titanate was added to 12.5 mL of isopropyl alcohol and stirred at room temperature for 30 min. Then, 11.5 mL of TPAOH (1.2 mol / L) and 26.5 mL of deionized water were added to form Solution II. The molar ratio of tetrapropylammonium hydroxide, tetrabutyl titanate, isopropyl alcohol, and water was 1:0.188:11.83:142. Solution II was added to Solution I, and the temperature was raised to 95°C to evaporate the alcohol to 60 mL. The volume was then filled with water to 100 mL. Finally, 40 mL of an aqueous solution containing 2.28 g of ammonium carbonate was added to form solution III; wherein the molar ratio of tetrapropylammonium hydroxide, ammonium carbonate, and water was 1:0.23:110.

[0104] Solution III was hydrothermally pretreated at 170° C. for 72 h and then cooled to room temperature. The obtained product was separated and the liquid product was used as the modification liquid.

[0105] The modified solution was added to a reactor at a ratio of 1 g m-TS-1 to 13.5 mL of liquid and stirred thoroughly. The catalyst was then hydrothermally treated at 170°C for 72 hours. The hydrothermal product was cooled, separated, and the solid phase was dried at 100°C for 12 hours and calcined at 540°C for 6 hours to obtain the hydrothermally modified TS-1 catalyst, labeled Ti-TS-1.

[0106] The obtained catalyst Ti-TS-1 contains Ti(OH)(OSi)3, Ti(OH)2(OSi)3, Ti(OH)4(OSi)2 and anatase TiO2, and the molar ratio of each species is 1.04:1:1.24:0.68, among which the molar ratio of Ti(OH)2(OSi)3 pentacoordinate titanium species and Ti(OH)4(OSi)2 hexacoordinate titanium species is 1:1.24. Calculated by the amount of substance, the sum of the amounts of the two substances accounts for 0.84% ​​of the amount of the catalyst substance.

[0107] Example 7

[0108] The m-TS-1 catalyst prepared in Example 1 was used as the unmodified TS-1 molecular sieve.

[0109] A 0.22 mol / L aqueous ammonium carbonate solution was added to a reactor at a ratio of 1 g m-TS-1 to 13.5 mL of liquid, stirred evenly, and then hydrothermally treated at 170°C for 72 hours. The hydrothermal product was cooled and separated, and the solid product was dried at 100°C for 12 hours and calcined at 540°C for 6 hours to obtain the hydrothermally modified TS-1 catalyst, labeled N-TS-1.

[0110] In the obtained catalyst N-TS-1, Ti(OSi)4, Ti(OH)4(OSi)2 and anatase TiO2 are present at the same time, and the molar ratio of each species is 4.11:1:0.41, among which the molar ratio of Ti(OSi)4 tetracoordinate titanium species and Ti(OH)4(OSi)2 hexacoordinate titanium species is 4.11:1. Calculated by the amount of substance, the amount of Ti(OH)4(OSi)2 accounts for 0.27% of the amount of catalyst substance.

[0111] Example 8

[0112] The m-TS-1 catalyst prepared in Example 1 was used as the unmodified TS-1 molecular sieve.

[0113] 70 mL of 0.10 mol / L ammonium carbonate aqueous solution was hydrothermally pretreated at 170° C. for 72 h and then cooled to room temperature to obtain a modified solution.

[0114] The modified solution was added to a reactor at a ratio of 1 g m-TS-1 to 13.5 mL of liquid, stirred evenly, and then hydrothermally treated at 170°C for 72 hours. The hydrothermal product was cooled and separated, and the solid phase product was dried at 100°C for 12 hours and calcined at 540°C for 6 hours to obtain the hydrothermally modified TS-1 catalyst, labeled HN-TS-1.

[0115] The obtained catalyst HN-TS-1 contains Ti(OH)(OSi)3, Ti(OH)2(OSi)3, Ti(OH)4(OSi)2 and anatase TiO2, and the molar ratio of each species is 0.93:1:1.46:1.08, among which the molar ratio of Ti(OH)2(OSi)3 pentacoordinate titanium species and Ti(OH)4(OSi)2 hexacoordinate titanium species is 1:1.46. Calculated by the amount of substance, the sum of the amounts of the two substances accounts for 0.83% of the amount of the catalyst substance.

[0116] Example 9

[0117] The unmodified TS-1 molecular sieve 1 was prepared by the following steps:

[0118] 7.1) In a 250-mL three-necked flask, add 35.5 mL of tetraethyl orthosilicate, 40.5 mL of 1.2 mol / L TPAOH, and 12 mL of deionized water. Stir at 40°C for 5 h to form Solution J. The molar ratio of tetrapropylammonium hydroxide, tetraethyl orthosilicate, and water is 1:3.27:47.

[0119] 7.2) Add 1.35 mL of tetrabutyl titanate to 12.5 mL of isopropyl alcohol and stir at room temperature for 30 min. Then, add 11.5 mL of a 1.2 mol / L aqueous solution of TPAOH and 26.5 mL of deionized water to form Solution K. The molar ratio of tetrapropylammonium hydroxide, tetrabutyl titanate, isopropyl alcohol, and water is 1:0.287:11.83:142.

[0120] 7.3) Add Solution K to Solution J, then heat to 95°C to evaporate the alcohol to 60 mL, then add water to 100 mL. Finally, add 40 mL of an aqueous solution containing 2.28 g of ammonium carbonate to form Solution L. The molar ratio of the total molar amount of tetrapropylammonium hydroxide used in Steps 7.1) and 7.2) to the molar ratio of the ammonium carbonate and water used in Step 7.3) is 1:0.23:110.

[0121] 7.4) Solution L was hydroheated at 170°C for 72 hours and then cooled to room temperature. The resulting product was separated, and the solid product was dried at 100°C for 12 hours and calcined at 540°C for 6 hours to obtain unmodified m1-TS-1 catalyst (i.e., unmodified TS-1 molecular sieve 1).

[0122] 7.5) Use 0.1 mol / L tetrapropylammonium hydroxide aqueous solution directly as the modification solution; add the modification solution to the reactor at a ratio of 1 g ml-TS-1 to 10 mL of 0.1 mol / L tetrapropylammonium hydroxide aqueous solution, stir evenly, and then hydrothermally treat at 200°C for 72 hours. Cool the hydrothermal product, separate it, and dry the solid product at 100°C for 12 hours, then calcine it at 540°C for 6 hours to obtain the hydrothermally modified TS-1 catalyst, labeled as T 200 -TS-1.

[0123] After testing, the obtained catalyst T 200 -TS-1 contains Ti(OH)(OSi)3, Ti(OH)2(OSi)3, Ti(OH)4(OSi)2 and anatase TiO2 at the same time, with the molar ratio of each species being 1.12:1:0.93:0.81. In terms of the amount of substance, the sum of the amounts of pentacoordinate titanium species and hexacoordinate titanium species accounts for 0.79% of the amount of the catalyst substance.

[0124] Evaluation of Catalytic Performance of Titanium Silica Molecular Sieve

[0125] The catalytic performance of the catalyst was evaluated by propylene epoxidation to produce propylene oxide. 0.20 g of catalyst powder (m cat. =0.20g) and 34mL of 2.0mol / L hydrogen peroxide-methanol solution (V(H2O2-CH3OH)=34mL), the reactor was sealed and filled with propylene to ensure that the propylene pressure (P) was 0.6MPa during the entire reaction process, and the reaction was carried out at 50℃ for 1h. 200 -TS-1 catalyst, the concentration of hydrogen peroxide-methanol solution was 3.0 mol / L, and the reaction temperature was 40°C.

[0126] Residual H₂O₂ in the system was measured by iodine reduction titration, and product composition was analyzed using a Tianmei 7890F gas chromatograph. Chromatography was performed using an FID detector, a PEG-20m capillary column (30m×0.25m×0.4μm), a column temperature of 60°C, an injector at 200°C, and a detector at 180°C. Propylene oxide (PO) was the target product, while 1,2-propylene glycol (PG) and monomethyl ether (MME) were byproducts. The hydrogen peroxide conversion (X(H2O2)), propylene oxide selectivity (S(PO)), hydrogen peroxide utilization (U(H2O2)), and propylene oxide yield (Y(PO)) were calculated by the following formula, where n0(H2O2) and n(H2O2) represent the amount of hydrogen peroxide before and after the reaction, Δn(H2O2) represents the amount of hydrogen peroxide consumed in the reaction, and n(PO), n(MME), and n(PG) represent the amounts of PO, MME, and PG. X(H2O2) = 1 - n(H2O2) / n0(H2O2)

[0127] S(PO)=n(PO) / ((n(PO)+n(MME)+n(PG))

[0128] U(H2O2)=(n(PO)+n(MME)+n(PG)) / (n0(H2O2)×X(H2O2))

[0129] Y(PO)=X(H2O2)×S(PO)×U(H2O2)

[0130] Catalytic performance of the catalysts before and after modification in the epoxidation of propylene to produce propylene oxide

[0131]

[0132] a: hydrogen peroxide conversion rate, b: target product propylene oxide selectivity, c: hydrogen peroxide utilization rate, d: propylene oxide yield.

[0133] It can be seen from the above experimental results that by modifying the unmodified TS-1 molecular sieve to contain penta-coordinated titanium species Ti(OH)2(OSi)3 and / or hexa-coordinated titanium species Ti(OH)4(OSi)2, the catalytic performance of the TS-1 molecular sieve can be improved, especially the catalytic activity and catalytic performance in the epoxidation of propylene to produce propylene oxide.

[0134] The above description is merely the principle and preferred embodiments of the present application. It should be noted that, for those skilled in the art, implementation methods obtained by appropriately combining the technical solutions disclosed in different embodiments are also included in the technical scope of the present invention. Based on the principles of the present application, several other variations can be made and should also be considered as the scope of protection of the present application.

Claims

1. A titanium-containing compound, characterized in that The titanium-containing compound has the expression Ti(OH) x (OSi) y , wherein x is 2 and y is 3, or x is 4 and y is 2; when the titanium-containing compound is a five-coordinate titanium species with x being 2 and y being 3, it has a wavelength of 510 cm in the ultraviolet resonance Raman spectrum excited at 257 nm or 266 nm. -1 、685cm -1 and 1125cm -1 The Raman spectrum peak has an absorption peak of 225nm in its ultraviolet-visible diffuse reflectance spectrum; when the titanium-containing compound is a hexacoordinate titanium species with x being 4 and y being 2, it has an absorption peak of 441cm in the ultraviolet resonance Raman spectrum excited at 257nm or 266nm. -1 、705cm -1 、1125cm -1 and 1342cm -1 The Raman peak of the UV-visible diffuse reflectance spectrum has an absorption peak at 271 nm. The position error of the above Raman peaks is within ±5 cm. -1 The position error of the above absorption peaks is within ±5nm.

2. A titanium silicon molecular sieve catalyst, characterized in that: Which includes a hexacoordinated titanium species expressed as Ti(OH)4(OSi)2, or, includes a pentacoordinated titanium species expressed as Ti(OH)2(OSi)3 and a hexacoordinated titanium species expressed as Ti(OH)4(OSi)2; When the titanium silicate molecular sieve catalyst contains both the five-coordinated titanium species and the six-coordinated titanium species, the titanium silicate molecular sieve catalyst has a wavelength of 441 cm-1 in the ultraviolet resonance Raman spectrum excited at 257 nm or 266 nm. -1 、705cm -1 、1125cm -1 and 1342cm -1 Raman spectrum peak, its ultraviolet-visible diffuse reflectance spectrum has absorption peaks at 225nm and 271nm; in the titanium silicon molecular sieve catalyst, the molar ratio of the five-coordinate titanium species expressed as Ti(OH)2(OSi)3 and the six-coordinate titanium species expressed as Ti(OH)4(OSi)2 is 1:0.93-3; When the titanium silicate molecular sieve catalyst contains the hexacoordinated titanium species but does not contain the pentacoordinated titanium species, the titanium silicate molecular sieve catalyst has a wavelength of 441 cm-1 in the ultraviolet resonance Raman spectrum excited at 257 nm or 266 nm. -1 、705cm -1 、1125cm -1 and 1342cm -1 The Raman spectrum peak of the UV-visible diffuse reflectance spectrum has an absorption peak at 271nm; The position error of the above Raman peaks is ±5cm -1 The position error of the above absorption peaks is within ±5nm.

3. The titanium silicon molecular sieve catalyst according to claim 2, characterized in that When the titanium silicate catalyst contains both the pentacoordinate titanium species and the hexacoordinate titanium species, the molar ratio of the pentacoordinate titanium species represented by the expression Ti(OH)2(OSi)3 to the hexacoordinate titanium species represented by the expression Ti(OH)4(OSi)2 is 1:1-3.

4. The titanium silicon molecular sieve catalyst according to claim 2, characterized in that Calculated by amount, the sum of the amounts of the pentacoordinated titanium species and the hexacoordinated titanium species accounts for 0.1% to 5% of the amount of the catalyst.

5. The method for preparing the titanium silicon molecular sieve catalyst according to any one of claims 2 to 4, characterized in that: The preparation method comprises the following steps: 1) obtaining unmodified TS-1 molecular sieve; 2) preparing a modified liquid; 3) mixing the modified liquid with the unmodified TS-1 molecular sieve and performing hydrothermal treatment, and then drying and calcining the resulting solid phase product to obtain the titanium silicalite molecular sieve catalyst; In step 2), the modified solution is prepared by one of the following methods 1 to 4: Method 1: prepare ammonium carbonate into an ammonium carbonate aqueous solution, and use it as a modification liquid after hydrothermal pretreatment, or use it directly as a modification liquid without hydrothermal pretreatment; Method 2: Tetrapropylammonium hydroxide is prepared into a 0.06-1.2 mol / L tetrapropylammonium hydroxide aqueous solution, without the hydrothermal pretreatment, and ammonium carbonate is optionally added thereto, and the solution is directly used as a modification solution; in step 3), the hydrothermal treatment is carried out at 199-220° C. for 1 to 120 hours; the molar ratio of ammonium carbonate to tetrapropylammonium hydroxide is 0-2:1; Method 3: Tetrapropylammonium hydroxide and optional auxiliary raw materials are mixed in water and heated at 25-60°C for 0.5-12 hours; then ammonium carbonate is added and hydrothermally pretreated at 100-250°C for 1-120 hours to obtain a modified solution; the auxiliary raw materials are selected from one or more of tetraethyl orthosilicate, tetrabutyl titanate, isopropyl alcohol, and ethanol; Method 4: Tetrapropylammonium hydroxide and optional auxiliary raw materials are mixed in water and heated at 25-60°C for 0.5-12 hours to obtain solution I; another portion of tetrapropylammonium hydroxide is mixed with another portion of the optional auxiliary raw materials in water to obtain solution II; after mixing solution II with solution I, ammonium carbonate is added, and hydrothermal pretreatment is performed at 100-250°C for 1-120 hours to obtain a modified solution; In solution I, the auxiliary raw material is selected from one or both of ethyl orthosilicate and / or ethanol; in solution II, the auxiliary raw material is selected from tetrabutyl titanate and / or isopropyl alcohol.

6. The preparation method according to claim 5, characterized in that In step 3), the amount of the modification liquid is 1 to 100 mL relative to 1 g of the unmodified TS-1 molecular sieve; the temperature and time of the hydrothermal treatment are 100 to 250° C. and 1 to 120 h, respectively; And / or, in step 3), the calcination is performed at 400-600° C. for 4-12 hours.

7. The method for preparing the titanium silicon molecular sieve catalyst according to claim 5, characterized in that: In step 2), the modified solution is prepared by the method 1; In the first embodiment, the concentration of the aqueous ammonium carbonate solution is 0.05 mol / L-5 mol / L; And / or, in the first embodiment, the hydrothermal pretreatment is a hydrothermal treatment at 100 to 250° C. for 1 to 120 hours; And / or, in the first embodiment, when the aqueous ammonium carbonate solution is used as a modifying liquid after the hydrothermal pretreatment, in step 3), the hydrothermal treatment is carried out at 100-250°C for 1-120 hours; when the aqueous ammonium carbonate solution is directly used as a modifying liquid without hydrothermal pretreatment, in step 3), the hydrothermal treatment is carried out at 150-200°C for 1-120 hours.

8. The method for preparing the titanium silicon molecular sieve catalyst according to claim 5, characterized in that: In step 2), the modified solution is prepared by the method 3; In the third method, the molar ratio of the ethyl orthosilicate to the tetrapropylammonium hydroxide is 0-4.5:1; the molar ratio of the tetrabutyl titanate to the tetrapropylammonium hydroxide is 0-0.1:1; the molar ratio of the isopropyl alcohol to the tetrapropylammonium hydroxide is 0-15:1; the molar ratio of the ethanol to the tetrapropylammonium hydroxide is 0-20:1; when the auxiliary raw material in step 2) includes ethyl orthosilicate and / or tetrabutyl titanate, the modified liquid is a liquid phase obtained by solid-liquid separation of the mixture obtained by the hydrothermal pretreatment; The molar ratio of the tetrapropylammonium hydroxide to water is 1:10-300, and the molar ratio of the tetrapropylammonium hydroxide to the ammonium carbonate is 1:0.1-1.

9. The preparation method according to claim 8, characterized in that In the third method, the molar ratio of the ethyl orthosilicate to the tetrapropylammonium hydroxide is 0.1-3.5:1; and / or, the molar ratio of the tetrabutyl titanate to the tetrapropylammonium hydroxide is 0.005-0.07:1; and / or, the molar ratio of the isopropyl alcohol to the tetrapropylammonium hydroxide is 0.1-13.5:1; And / or, the molar ratio of the ethanol to the tetrapropylammonium hydroxide is 0.1-15:

1.

10. The preparation method according to claim 8, characterized in that In the third method, after the heating treatment and before the addition of ammonium carbonate, the following operation is also included: heating to 85-95°C to evaporate to 1 / 3-1 / 2 of the volume before heating, and then adding water to 0.7-3 times the volume before heating.

11. The method for preparing a titanium silicon molecular sieve catalyst according to claim 5, characterized in that: In the step 2), the modified liquid is prepared by the method 4; In the fourth method, after solution II and solution I are mixed, the temperature is raised to 85-95°C to evaporate to 1 / 3-1 / 2 of the volume before heating before adding the ammonium carbonate, and then water is added to 0.7-3 times the volume before heating; In the solution I, the molar ratio of the tetrapropylammonium hydroxide to the ethyl orthosilicate is 1:0-4.5; the molar ratio of the tetrapropylammonium hydroxide to the ethanol is 1:0-20; and the molar ratio of the tetrapropylammonium hydroxide to water is 1:10-100; In the solution II, the molar ratio of tetrapropylammonium hydroxide to tetrabutyl titanate is 1:0-0.4; the molar ratio of tetrapropylammonium hydroxide to isopropyl alcohol is 1:0-15; and the molar ratio of tetrapropylammonium hydroxide to water is 1:10-250. When the auxiliary raw material in step 2) includes ethyl orthosilicate and / or tetrabutyl titanate, the modified liquid is a liquid phase obtained by solid-liquid separation of the mixture obtained by the hydrothermal pretreatment; The volume ratio of the solution I to the solution II is 1:0.16-1.2, and the molar ratio of the total amount of the tetrapropylammonium hydroxide to the amount of the ammonium carbonate is 1:0.1-1.

12. The preparation method according to claim 11, characterized in that In the solution I, the molar ratio of the tetrapropylammonium hydroxide to the ethyl orthosilicate is 1:0.1-3.50, and the molar ratio of the tetrapropylammonium hydroxide to the ethanol is 1:0.1-15; And / or, in the solution II, the molar ratio of tetrapropylammonium hydroxide to tetrabutyl titanate is 1:0.005-0.3, and the molar ratio of tetrapropylammonium hydroxide to isopropyl alcohol is 1:0.1-13.

5.

13. The preparation method according to any one of claims 5 to 12, characterized in that: The unmodified TS-1 molecular sieve was prepared according to the following steps: 1.1) mixing ethyl orthosilicate and tetrapropylammonium hydroxide in water and hydrolyzing them to obtain solution A; wherein the molar ratio of ethyl orthosilicate, tetrapropylammonium hydroxide, and water is 0.1-4.5:1:20-60; and the hydrolysis is carried out at 25-60° C.; 1.2) Mixing isopropyl alcohol and tetrabutyl titanate, stirring at 10-30° C. for 0.25-1.5 h, and then adding tetrapropylammonium hydroxide aqueous solution to obtain solution B; wherein the molar ratio of tetrabutyl titanate, isopropyl alcohol, tetrapropylammonium hydroxide, and water in solution B is 0.05-0.4:0.5-13.5:1:10-160; 1.3) Solution A and Solution B are mixed in a volume ratio of 1:0.16-1.2, and ammonium carbonate is added to form Solution C, wherein the ratio of ammonium carbonate to the total molar amount of tetrapropylammonium hydroxide used in steps 1.1) and 1.2) is 0.1-1:1; 1.4) Solution C is hydrothermally treated at 100-250° C. for 1-120 h, cooled, and separated to obtain a solid phase product and a liquid phase product. The solid phase product is dried and calcined at 400-600° C. for 4-12 h to obtain the unmodified TS-1 molecular sieve.

14. The preparation method according to claim 13, characterized in that In step 1.3), after solution A and solution B are mixed, alcohol is evaporated at 80-95° C. before adding the ammonium carbonate, and the ratio of the volume after evaporation to the volume before evaporation is 1 / 3-1 / 2, and then water is added to 0.7-3 times the volume before evaporation.

15. The preparation method according to claim 13, characterized in that The liquid phase product is directly used as the modified liquid in step 3).

16. An application, characterized in that: The titanium-containing compound according to claim 1, the titanium silicate molecular sieve catalyst according to any one of claims 2 to 4, or the titanium silicate molecular sieve prepared by the preparation method according to any one of claims 5 to 15 is used as a catalyst in olefin epoxidation, ketone ammoximation, aromatic hydrocarbon hydroxylation, and oxidation of alkanes and alcohols.

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