Alkali metal-modified titanium silicalite molecular sieve, method of making and use thereof

Abstract

An alkali metal-modified titanium-silicon molecular sieve, characterized in that the molecular sieve contains titanium, silicon, oxygen, and alkali metal elements, and is characterized by Raman spectroscopy using a 325 nm light source, showing a value at 990±20 cm⁻¹. ‑1 A titanium species signal peak exists within the range, at 1125±20 cm⁻¹. ‑1 No obvious titanium species signal peak was observed within the range of 800±20 cm⁻¹. ‑1 A molecular sieve framework structure signal peak exists within the range, calculated with peak area as intensity, 990±20 cm⁻¹. ‑1 Signal peak intensity and 800±20cm ‑1 The ratio of signal peak intensity I(990) / I(800) is (0.2-2):1.

Description

Technical Field

[0001] This invention belongs to the field of molecular sieve catalyst technology, and more specifically relates to titanium-silicon molecular sieves, methods for modifying molecular sieves, and their application in aldol condensation reactions. Background Technology

[0002] Methyl acrylate (Macrylate) is an important organic intermediate widely used in industries such as rubber, leather, pharmaceuticals, and coatings. Currently, there are several main methods for producing Macrylate: propylene oxidation, acrylonitrile hydrolysis, and propane oxidation. Industrial production primarily uses propylene oxidation, which is technically and economically sound but inefficient. Acrylonitrile hydrolysis has low yields, and sulfuric acid cannot be recycled. Propane oxidation is a commonly used method, although inexpensive, but with low product yields. The condensation reaction of coal-based methyl acetate (or acetic acid) and formaldehyde to prepare Macrylate is a very important and valuable synthetic route. This route not only has low production costs but also effectively controls the discharge of polluting wastewater, making it highly promising for application. Researching and developing catalysts with high catalytic activity is key to the industrialization of this process.

[0003] The literature reports on the research progress of acetic acid (ester)-formaldehyde condensation to acrylic acid (ester) (Chemical Industry Progress, 2021, 40(4): 2005-2015). Currently, the main catalysts used for this route include VPO catalysts, alkali metal / alkaline earth metal catalysts, and ionic liquid catalysts. VPO catalysts have high catalytic efficiency, but many side reactions and are prone to deactivation. Compared with VPO, alkali metal catalysts have no oxidative byproducts and higher selectivity, but their catalytic efficiency is slightly lower. Ionic liquids have mild reaction conditions and high selectivity, but product separation is difficult and the catalyst is difficult to reuse. In comparison, alkali metal catalysts have a simpler preparation process, a larger adjustment range, high product selectivity, and are easier to realize industrial applications.

[0004] CN108097290A reports a catalyst for preparing acrylic acid / methyl acrylate from raw materials containing carbon monoxide and formaldehyde compounds. This catalyst is primarily obtained by metal modification of commercially available MOR-configured molecular sieves with different silica-to-alumina ratios using at least one of copper, silver, iron, cobalt, nickel, and gallium via impregnation, ion exchange, and in-situ synthesis methods. The catalyst exhibits a maximum selectivity of 88.2% for acrylic acid and 5.3% for methyl acrylate.

[0005] CN106693941A reports a catalyst with Li, Na, K, Rb, Cs, Mg, Ca, Sr, and Ba as active components and Al2O3 as the support, prepared by co-precipitation. Under the condition of a molar ratio of methyl acetate:formaldehyde:methanol of 1:2:2, the conversion rate of methyl acetate is 34.4% and the selectivity of methyl acrylate is 93.4%.

[0006] CN104258901A discloses a Cs-supported pure silica molecular sieve catalyst, using KIT-6 as a support and different contents of Cs as active components. It is applied to the reaction of methyl acetate and formaldehyde aldol condensation to prepare methyl acrylate. Under the condition that the molar ratio of methyl acetate, formaldehyde and methanol is 1:2:2, the conversion rate of methyl acetate can reach up to 35% and the selectivity of methyl acrylate can reach up to 94%.

[0007] Teng He et al. reported in Catalysis Letters, 2019, 149(2):373-389 that cesium-supported SiO2 was used as a catalyst in the aldol condensation of methyl acetate and formaldehyde to prepare methyl acrylate. Under the conditions of a molar ratio of methyl acetate, formaldehyde and methanol of 1:2:2 and a reaction temperature of 390℃, the conversion rate of methyl acetate was about 35% and the selectivity of methyl acrylate was 85-90%.

[0008] Studies have shown that among various catalysts that catalyze the aldol condensation reaction of methyl acetate and formaldehyde, silica-supported Cs alkali metal catalysts have the best performance, but their catalytic activity is not ideal. Summary of the Invention

[0009] One objective of this invention is to provide a modified titanium-silicon molecular sieve and its preparation method that differ from existing technologies. Another objective is to provide a catalyst with the modified titanium-silicon molecular sieve as the active component. A third objective is to provide a method for aldol condensation reaction.

[0010] To achieve one of the above objectives, the present invention provides an alkali metal-modified titanium-silicon molecular sieve, characterized in that the molecular sieve contains titanium, silicon, oxygen, and alkali metal elements, and is characterized by Raman spectroscopy using a 325 nm light source, showing a value at 990±20 cm⁻¹. -1 A titanium species signal peak exists within the range, at 1125±20 cm⁻¹. -1 No obvious titanium species signal peaks were observed within the range.

[0011] To achieve one of the objectives of this invention, this invention also provides a method for preparing the alkali metal-modified titanium-silicon molecular sieve of the present invention, characterized in that the titanium-silicon molecular sieve used as the modifying raw material is mixed with an alkali metal hydroxide or an alkali metal salt and water and / or an organic solvent, then the water and / or organic solvent are removed, and then the mixture is dried and calcined to obtain the alkali metal-containing titanium-silicon molecular sieve. The mixing treatment is carried out at 50-100°C, the gauge pressure is 0.1-5 MPa, and the treatment time is 0.5-12 h.

[0012] To achieve the second objective of this invention, this invention provides a titanium-silicon molecular sieve catalyst, characterized in that it contains either the alkali metal-modified titanium-silicon molecular sieve provided by this invention or the alkali metal-modified titanium-silicon molecular sieve prepared by the preparation method provided by this invention, wherein the alkali metal-modified titanium-silicon molecular sieve accounts for 5%-100% of the weight of the titanium-silicon molecular sieve catalyst.

[0013] To achieve the third objective of this invention, this invention also provides an application of a titanium-silicon molecular sieve catalyst. This application involves the preparation method of a carbonyl compound from the titanium-silicon molecular sieve catalyst of this invention, in which a carbonyl compound having α-H undergoes a carbon-carbon bond coupling reaction with another carbonyl compound in the presence of the titanium-silicon molecular sieve catalyst of this invention to generate a carbonyl compound having β-hydroxyl groups or a carbonyl compound having α,β-unsaturated bonds.

[0014] Compared with the prior art, the advantages of the present invention are as follows:

[0015] (1) By modifying titanium in titanium-silicon molecular sieves with alkali metal under specific conditions, new active center species are generated, which have Raman spectral characterization characteristics and IR characterization characteristics that are different from those of existing technologies. The active center species has good catalytic performance and can improve catalytic activity while providing good product selectivity.

[0016] (2) Alkali metal modification methods are simple, have short steps, and have a wide range of raw material sources, making them suitable for large-scale industrial applications and environmentally friendly. Attached Figure Description

[0017] Figure 1 The IR spectra of Example 1 and Comparative Example 1 are shown below;

[0018] Figure 2 The UV-Raman spectra of Example 1 and Comparative Example 1 are shown. Detailed Implementation

[0019] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0020] The alkali metal-modified titanium-silicon molecular sieve provided by this invention is characterized by containing titanium, silicon, oxygen, and alkali metal elements, and is characterized by Raman spectroscopy using a 325 nm light source, showing a value at 990±20 cm⁻¹. -1 A titanium species signal peak exists within the range, at 1125±20 cm⁻¹. -1 No obvious titanium species signal peaks were observed within the range.

[0021] Laser Raman spectroscopy using a 325nm light source can effectively excite the resonance of titanium species, providing a strong signal intensity of titanium species. Characterization of the alkali metal-modified titanium-silicon molecular sieve provided in this invention using Raman spectroscopy with a 325nm light source reveals a resonance intensity at 990±20cm⁻¹. -1 A recognizable titanium species signal peak exists within the range, preferably at 990±10 cm⁻¹. -1 More preferably 990±5cm -1 990±20cm -1 The definition of an identifiable titanium species signal peak within the range is: calculated with peak area as intensity, 990±20 cm⁻¹. -1 Signal peak intensity and 800±20cm -1 The ratio of signal peak intensity I(990) / I(800) is (0.2-2):1, preferably (0.5-1.6):1, and more preferably (0.8-1.3):1. At 1125±20cm -1 No obvious titanium species signal peak was observed within the range. The peak was located at 1125±20 cm⁻¹. -1 The definition of no obvious titanium species signal peak within the range is: calculated based on peak area as intensity, 1125±20cm. -1 Signal peak intensity and 800±20cm -1 The ratio of signal peak intensity I(1125) / I(800) is <0.1, more preferably <0.05, and even more preferably, characterized by Raman spectroscopy using a 325nm light source, the alkali metal-modified titanium-silicon molecular sieve provided by this invention does not have a 1125cm peak intensity. -1 A signal peak appears.

[0022] When the alkali metal-modified titanium-silicon molecular sieve provided by this invention was characterized using Raman spectroscopy with a 325 nm light source, it was also found that at 800 ± 20 cm⁻¹... -1 A molecular sieve framework structure signal peak exists within the range, and the intensity is calculated based on the peak area, 990±20 cm⁻¹. -1 Signal peak intensity and 800±20cm -1 The ratio of signal peak intensity I(990) / I(800) is (0.2-2):1, preferably (0.5-1.6):1, and more preferably (0.8-1.3):1.

[0023] literature( Phys.Chem.Chem.Phys. Studies (2016, 18, 190-196) have shown that, generally speaking, in Raman spectra, 960±10 cm⁻¹ -1 and 1125±10cm -1 The signal peaks at these locations represent the vibrational signals of framework titanium. These peaks are present in most titanium-silicon molecular sieves, indicating the presence of framework titanium species within the sieve. The alkali metal-modified titanium-silicon molecular sieve provided by this invention exhibits a signal peak at 960±10 cm⁻¹.-1 and 1125±10cm -1 None of them had obvious characteristic peaks, but at 990±20cm -1 A new characteristic peak appears. The Raman spectral characterization of alkali metal-modified titanium-silicon molecular sieves using a 325 nm light source employs conventional methods in the field.

[0024] Fourier transform infrared spectroscopy (FT-IR) is one of the important methods for analyzing the framework structure of molecular sieves. The spectral bands induced by vibrations in the molecular sieve framework are generally in the mid- to far-infrared region. The positions of the spectral bands of internal vibrations are not sensitive to changes in the framework structure, while the spectral bands of externally connected vibrations are more significantly affected by structural changes. A study in the literature (Chemical Communications, 1982(24):1413-1415.) shows that in the infrared spectrum of TS-1 molecular sieves with an MFI structure, the 800 cm⁻¹... -1 The characteristic peak at 960 cm⁻¹ is a skeletal vibration peak. -1 The characteristic peak at 800 cm⁻¹ is the stretching vibration peak of the Si-O bond in Ti-O-Si, and is also a necessary parameter for titanium to enter the molecular sieve framework. For general titanium-silicon molecular sieves, signal peaks can appear at these two locations, indicating the presence of framework titanium species in the molecular sieve. The alkali metal-modified titanium-silicon molecular sieve provided by this invention exhibits a characteristic peak at 800 cm⁻¹. -1 The presence of skeletal vibrational peaks indicates that the prepared molecular sieve possesses an MFI structure, but the 960 cm⁻¹ peak... -1 The characteristic peaks at these locations are significantly weak or even disappear, indicating that the alkali metals in the titanium-silicon molecular sieve of this invention interact with the Si-O or Ti-O species in Ti-O-Si. Therefore, the titanium-silicon molecular sieve of this invention is characterized by IR spectroscopy, with peak height as the intensity, and the value is 960 ± 20 cm⁻¹. -1 The signal peak intensity is at 800±20cm -1 The ratio of signal peak intensity I(960) / I(800) is <0.5, preferably <0.3, more preferably <0.15, more preferably <0.05, even more preferably <0.01, and most preferably 960±20cm. -1 The signal peak disappears. In this invention, the IR spectrum test method for alkali metal-modified titanium-silicon molecular sieves is a conventional method in the art.

[0025] Based on the Raman and infrared spectral characterization described above, it can be seen that the alkali metal-containing titanium-silicon molecular sieve of the present invention interacts with the Si-O or Ti-O in Ti-O-Si, resulting in new catalytic active centers. Therefore, it is possible to obtain catalysts with performance superior to conventional titanium-silicon molecular sieves or alkali metal-containing catalysts.

[0026] In the alkali metal-modified titanium-silicon molecular sieve provided by this invention, the alkali metal element is selected from one or more of lithium, sodium, potassium, rubidium, and cesium, preferably one or more of potassium, rubidium, and cesium, more preferably one or more of rubidium and cesium, and even more preferably cesium. Preferably, the alkali metal element is uniformly dispersed in the molecular sieve. The molar ratio of titanium atoms to silicon atoms in the molecular sieve is obtained by X-ray fluorescence spectrometry (XRF). The molar ratio of the alkali metal element to silicon in the titanium-silicon molecular sieve is (0.001-0.1):1, preferably (0.003-0.06):1, even more preferably (0.005-0.05):1, even more preferably (0.01-0.04):1, and even more preferably (0.01-0.03):1. The molar ratio of titanium to silicon is (0.001-0.1):1, preferably (0.003-0.06):1, further preferably (0.005-0.04):1, and even more preferably (0.008-0.02):1.

[0027] The alkali metal-modified titanium-silica molecular sieve of the present invention, in principle, includes any suitable structural type or any suitable combination of structural types in its framework structure. Therefore, the usable molecular sieve structural types in principle include the following structural types: ABW, ACO, AEI, AEL, AEN, AET, AFG, AFI, AFN, AFO, AFR, AFS, AFT, AFY, AHT, ANA, APC, APD, AST, ASV, AFX, ATN, ATO, ATS, ATT, ATV, AWO, AWW, BCT, BEA, BEC, BIK, BOF, BOG, BOZ, BPH, BRE, BSV, CAN, CAS, CDO, CFI, CGF, SCO, CFI, SGF, CGS, CHA, CHI, CLO, CON, CZ. P, DAC, DDR, DFO, DFT, DOH, DON, EAB, EDI, EWT, EON, EPI, ERI, ESV, ETR, EUO, FAU, FER, FRA, GIS, GIU, GME, GON, GOO, HEU, IFR, IHW, ISV, ITE, I TH, ITW, IWR, IWW, IWV, JBW, JNT, JOZ, JRY, JSN, JSR, JST, JSW, KFI, LAU, LEV, LIO, LIT, LOS, LOV, LTA, LTF, LTJ, LTL, LTN, MAR, MAZ, MEI, MEL, M EP, MER, MFI, MFS, MON, MOR, MOZ, MRT, MSE, MSO, MTF, MTN, MTT, MTW, MVY, MWF, MWW, NAB, NAT, NES, NON, NPO, NPT, NSI, OBW, OFF, OKO, OSI, OSO, OWE, PAR, PAU, PCR, PHI, PON, POR, POS, PSI, PTY, PUN, PWN, PWO, PWW, RHO, RON, RRO, RSN, RTE, RTH, RUT, RWR, RWY, SAF, SAO, SAS, SAT, SAV, SBE, SBN, SBS, SBT, SFE, SFF, SFG, SFH, SFN, SFO, SFS, SFW, SGT, SIV, SOD, SOF, SOR, SOS, SOV, SSF, SSY, STF, STI, STT, STW, SVR, SVV, SWY, SYT, SZR, TER, THO, TOL, TON, TSC, TUN, UEI, UFI, UOS, UOV, UOZ, USI, UTL, UWY, VET, VFI, VNI, VSV, WEI, WEN, YFI, YUG, ZON, and hybrid structures consisting of two or more of these structural types.Preferably, the titanium-silicon molecular sieve has a crystal structure selected from one of MFI, MEL, MWW, BEA, MOR, and SVR. Alternatively, it may have an amorphous structure, including MCM-41, MCM-48, SBA-15, anatase, rutile, brookite, and amorphous titanium oxide derived from the hydrolysis of other titanium compounds.

[0028] Preferred crystal structures are MFI, MEL, and BEA structures, with further preferred crystal structures being MFI, MEL, and BEA structures possessing hierarchical pores. The hierarchical pore structure can be formed through direct synthesis or post-processing. For example, it can be synthesized using soft or hard template agents (silanization, cellulose method, carbon black method, etc.), or expanded by acid or alkali treatment (e.g., by treatment with hydrochloric acid, hydrofluoric acid, ammonium bifluoride, ammonium fluoride, sodium hydroxide, potassium hydroxide, ammonia, ammonium carbonate, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, etc.). The hierarchical pore structure can be a molecular sieve containing micropores and at least one mesopore and / or macropore, wherein the micropore diameter is less than 2 nm, the mesopore diameter is 2-50 nm, and the macropore diameter is greater than 50 nm. For example, it can be a hollow titanium-silicon molecular sieve (HTS) or a titanium-silicon molecular sieve with a non-uniform mesopore distribution.

[0029] The present invention also provides a method for preparing alkali metal modified titanium-silicon molecular sieves, characterized in that the titanium-silicon molecular sieve as the modifying raw material is mixed with an alkali metal hydroxide or an alkali metal salt and water and / or an organic solvent, then the water and / or organic solvent are removed, and then the mixture is dried and calcined to obtain the alkali metal-containing titanium-silicon molecular sieve. The mixing treatment is carried out at 50-100°C, the gauge pressure is 0.1-5 MPa, and the treatment time is 0.5-12 h.

[0030] In the preparation method, the titanium-silicon molecular sieve used as the modified raw material can be obtained by hydrothermal synthesis or post-synthesis. The preferred molar ratio of titanium to silicon is (0.001-0.1):1, more preferably (0.005-0.06):1, further preferably (0.01-0.04):1, and even more preferably (0.015-0.03):1.

[0031] In the preparation method, the alkali metal is selected from one or more of lithium, sodium, potassium, rubidium, and cesium. Potassium, rubidium, and cesium are preferred, more preferably one or more of rubidium and cesium, and even more preferably cesium. The hydroxide or salt includes alkali metal hydroxides, hydrochlorides, hypochlorites, chlorites, metachlorites, perchlorates, nitrates, sulfates, bisulfites, sulfites, bisulfites, phosphates, hydrogen phosphates, dihydrogen phosphates, high phosphates, metaphosphates, phosphites, hypophosphites, carboxylates, pyrophosphates, and C1-C... 20 It is one or more of carboxylates and inorganic salts. Preferably, it is a nitrate, carbonate, or hydroxide. More preferably, it is one or more of cesium hydroxide, cesium nitrate, cesium carbonate, cesium bicarbonate, and cesium acetate.

[0032] In the preparation method, the molar ratio of the alkali metal element to the silicon element in the titanium-silicon molecular sieve is preferably (0.001-0.1):1, more preferably (0.003-0.06):1, further preferably (0.005-0.05):1, even more preferably (0.01-0.04):1, and even more preferably (0.01-0.03):1.

[0033] In the preparation method, the organic solvent is selected from C1-C1. 10 alcohols, C3-C 10 Ketones, C2-C 10 The solvent can be an ester. Additionally, the solvent can be an aliphatic or aromatic solvent. Also, the solvent can be a chlorinated solvent, such as dichloromethane. More typically, the solvent is an aliphatic alcohol, typically selected from C1-C6 alkanols, such as methanol, ethanol, propanol, isopropanol, butanol, pentanol, and hexanol, more typically methanol, ethanol, or propanol. The amount of the inorganic or organic solvent added depends on the carrier. Preferably, the solvent is at least one of water, methanol, ethanol, and propanol. The molar ratio of the titanium silicate molecular sieve (based on SiO2) to the solvent is preferably 1:(10-100), more preferably 1:(20-80), more preferably 1:(25-60), and even more preferably 1:(30-50).

[0034] In the preparation method, the treatment is preferably carried out at 50-100℃, more preferably 55-90℃, and even more preferably 60-80℃. The pressure (gauge pressure) is 0.5-5MPa, preferably 0.5-4MPa, more preferably 0.8-3MPa, and even more preferably 1.2-2.5MPa. The treatment time is 0.5-12h, preferably 1-8h, and even more preferably 2-5h. Treatment under the aforementioned pressure and temperature conditions can effectively promote the interaction between alkali metals and titanium species in the titanium-silicon molecular sieve used as raw material, forming an alkali metal-modified titanium-silicon molecular sieve with special active centers.

[0035] In the preparation method, the method for removing water and / or organic solvents can be pressurized evaporation, atmospheric pressure evaporation, reduced pressure evaporation, filtration, centrifugation, sedimentation, etc., wherein reduced pressure evaporation is preferred, and more preferably, water and / or organic solvents are removed under a pressure (absolute pressure) of 10-80 kPa.

[0036] In the preparation method, the calcination atmosphere is preferably an oxygen-containing atmosphere, and more preferably an air atmosphere; the calcination temperature is determined according to the decomposition temperature of the alkali element precursor of the modifier, and is preferably <700℃ to prevent the decomposition of the alkali element precursor, and the calcination temperature is further preferably 400-600℃. To prevent significant changes in the carrier structure or specific surface area, the calcination time is 0.5-12h, and more preferably 3-8h.

[0037] The present invention also provides a catalyst containing titanium-silicon molecular sieves, comprising the alkali metal modified titanium-silicon molecular sieve of the present invention or the alkali metal modified titanium-silicon molecular sieve prepared by the above preparation method, wherein the alkali metal modified titanium-silicon molecular sieve accounts for 5%-100% of the weight of the catalyst containing titanium-silicon molecular sieves.

[0038] The present invention further provides a method for preparing a carbonyl-containing compound, wherein a carbonyl-containing compound having α-H undergoes a carbon-carbon coupling reaction with another carbonyl-containing compound in the presence of a catalyst to generate a carbonyl-containing compound having β-hydroxyl groups or a carbonyl-containing compound having α,β-unsaturated bonds, characterized in that the catalyst is the titanium-containing silicon molecular sieve catalyst provided by the present invention.

[0039] The method for preparing the carbonyl-containing compound involves using the alkali metal-modified titanium-silicon molecular catalyst provided by this invention to catalyze a carbonyl-containing compound with α-H to undergo a carbon-carbon bond coupling reaction with another carbonyl-containing compound to generate a carbonyl-containing compound with β-hydroxyl groups or a carbonyl-containing compound with α,β-unsaturated bonds (the α and β positions refer to the functional groups of hydrocarbon molecules, such as carbonyl, hydroxyl, carboxyl, etc., and the carbon atoms at their first and second adjacent positions).

[0040] The carbonyl-containing compounds include a first carbonyl compound and a second carbonyl compound, preferably having C1-C2 carbon atoms. 20 .in:

[0041] C1-C 12Alkyl groups, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, sec-pentyl, neopentyl, 1,2-dimethylpropyl, isopentyl, n-hexyl, isohexyl, sec-hexyl, n-heptyl, isoheptyl, n-octyl, n-nonyl, n-decyl, and n-dodecyl; preferably C1-C6 alkyl groups, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, sec-pentyl, neopentyl, 1,2-dimethylpropyl, isopentyl, n-hexyl, isohexyl, sec-hexyl, and especially preferably C1-C4 alkyl groups, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, and tert-butyl, and very particularly preferably methyl.

[0042] C3-C 12 Cycloalkyl groups, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, cycloundecyl, and cyclododecyl; preferably cyclopentyl, cyclohexyl, and cycloheptyl.

[0043] Examples of substituted cycloalkyl groups are: 2-methylcyclopentyl, 3-methylcyclopentyl, 2-methylcyclohexyl, 3-methylcyclohexyl, 4-methylcyclohexyl, 2-methoxycyclopentyl, 2-chlorocyclopentyl, 2-methylthiocyclohexyl and other derivatives.

[0044] C7-C 13 Aryl alkyl group, preferably C7-C 12 Phenylalkyl groups, such as benzyl, 1-phenylethyl, 2-phenylethyl, 1-phenylpropyl, 2-phenylpropyl, 3-phenylpropyl, 1-phenylbutyl, 2-phenylbutyl, 3-phenylbutyl and 4-phenylbutyl, with benzyl being particularly preferred.

[0045] C6-C 14 Aryl groups, such as phenyl, 1-naphthyl, 2-naphthyl, 1-anthrayl, 2-anthrayl, 9-anthrayl, 1-phenanthyl, 2-phenanthyl, 3-phenanthyl, 4-phenanthyl, 9-phenanthyl, preferably phenyl, are either unsubstituted or substituted with one or more of the following groups:

[0046] C1-C 12 Alkyl groups, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, sec-pentyl, neopentyl, 1,2-dimethylpropyl, isopentyl, n-hexyl, isohexyl, sec-hexyl, n-heptyl, isoheptyl, n-octyl, n-nonyl, n-decyl, and n-dodecyl; preferably C1-C6 alkyl groups, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, sec-pentyl, neopentyl, 1,2-dimethylpropyl, isopentyl, n-hexyl, isohexyl, sec-hexyl, and particularly preferably C1-C4 alkyl groups, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, and tert-butyl.

[0047] - Halogens, such as fluorine, chlorine, urethane, iodine, with chlorine being preferred.

[0048] -C1-C 12 Alkoxy groups, preferably C1-C6 alkoxy groups, such as methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy, tert-butoxy, n-pentoxy, isopentoxy, n-hexoxy, and isohexoxy, with methoxy, ethoxy, n-propoxy, and n-butoxy being particularly preferred.

[0049] Preferably, the first carbonyl compound contains α-H, and the second carbonyl compound contains α-H or does not contain α-H.

[0050] More preferably, the carbonyl compound without α-H is preferably formaldehyde, benzaldehyde, furfural, 5-hydroxyfurfural, 5-methylfurfural or its derivatives, and more preferably formaldehyde; the carbonyl compound containing α-H is preferably at least one of acetaldehyde, propionaldehyde, acetone, butyraldehyde, butanone, pentanal, pentanone, hexanal, hexanone, cyclohexanone, cyclopentanone, acetic acid, propionic acid, malonic acid, butyric acid, succinic acid, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, cyclohexyl acetate, methyl propionate, ethyl propionate, butyl propionate, dimethyl malonate, methyl butyrate, dimethyl succinate, ethyl butyrate or its derivatives.

[0051] In the method for preparing the carbonyl compound, the preferred conditions for the aldol condensation reaction are a molar ratio of the second carbonyl compound to the first carbonyl compound of 1:(0.5-5), a more preferred molar ratio of 1:(0.8-4), and a more preferred molar ratio of 1:(1-2). The feed stream also contains one or more diluents, including at least one of alcohols, ethers, alkanes, haloalkanes, and toluene, preferably methanol, cycloalkanes, diethyl ether, or toluene. The molar ratio of the diluent to the carbonyl compound is (10-0.5):1, more preferably (5-0.8):1, and more preferably (3-1):1.

[0052] In the method for preparing the carbonyl-containing compound of the present invention, the aldol condensation reaction is carried out in an atmosphere containing at least one gas selected from N2, He, Ar, CH4, C2H6, H2, CO, and CO2, more preferably in an atmosphere containing N2.

[0053] In the method for preparing the carbonyl-containing compound of the present invention, the temperature at which the aldol condensation reaction occurs is 200-500°C, preferably 250-480°C, and more preferably 300-400°C. Before the reaction, it is preferable to raise the temperature of the mixture to between 250-400°C, more preferably between 300-400°C. The reaction pressure is 0.01-2.5 MPa, preferably 0.5-1.0 MPa. The reaction liquid hourly space velocity (HLS) is 0.1-5 h⁻¹, based on the total mass of the carbonyl compound and the diluent.-1 0.1-3h -1 More preferably 0.1-2h -1 .

[0054] In the method for preparing carbonyl compounds of the present invention, the formaldehyde source is anhydrous formaldehyde, preferably methyl acetal, trioxymethylene, and oligooxymethylene. The inventors unexpectedly discovered that the catalyst of the titanium-containing silica molecular sieve provided by the present invention can surprisingly improve the activity and selectivity for aldol condensation of methylene sources such as formaldehyde with carboxylic acids or hydrocarbon esters such as methyl acetate to form olefinically unsaturated carboxylic acids. Therefore, in an optional specific embodiment, the aldol condensation reaction conditions of formaldehyde and methyl acetate include: a molar ratio of methyl acetate to formaldehyde of 1:2 to 5:1, a molar ratio of methanol to methyl acetate of 1:1 to 2:1, a reaction temperature of 350 to 400°C, a reaction pressure (gauge pressure) of 0 to 1 MPa, a nitrogen flow rate of 30 to 100 mL / min, and a liquid hourly space velocity of 0.1 to 2 h⁻¹. -1 Space velocity should be understood as mass space velocity, which refers to the ratio of the total mass flow rate (unit: mass / time) of reactants, substrates, and diluent to the mass of the catalyst. Therefore, the unit of space velocity is h. -1 .

[0055] In the method for preparing carbonyl compounds of the present invention, preferably, the aldol condensation reaction is carried out in a fixed-bed reactor, a fluidized-bed reactor, or a batch reactor.

[0056] Those skilled in the art will understand that, depending on the reactor used, the molecular sieve catalyst described in this invention can be either alkali metal-modified titanium-silicon molecular sieve powder or a shaped catalyst made from alkali metal-modified titanium-silicon molecular sieve. The separation of the product from the catalyst can be achieved in various ways. For example, when using a titanium-containing molecular sieve in its powdered framework as the catalyst, the product can be separated and the catalyst can be recovered and reused through sedimentation, filtration, centrifugation, evaporation, membrane separation, etc. Alternatively, the catalyst can be shaped and loaded into a fixed-bed reactor, and the catalyst can be recovered after the reaction is complete. Various methods for separating and recovering catalysts are discussed in existing literature and will not be elaborated upon here.

[0057] The present invention will be described in detail below through embodiments.

[0058] In this embodiment, the UV-Raman characterization experiment of the samples was conducted using a LabRAMHRUV-NIR confocal micro Raman spectrometer, manufactured by Jobin Yvon, France. Test conditions: room temperature, ambient pressure, spectral acquisition range 170-1200 cm⁻¹. -1Solid samples: The excitation wavelength was 325 nm, and the laser was a HeCd laser manufactured by Kimono Corporation, Japan. A 15x UV objective lens was used for testing. Single acquisition time was 300 s, with two cumulative samplings to eliminate fluorescence interference. A microscopic system composed of an Olympus microscope (Japan) was used. A 100 μm confocal pinhole was employed, and the first-order peak of single-crystal silicon was observed (520.7 cm⁻¹). -1 Correct peak position.

[0059] In this example, Fourier transform infrared spectroscopy was used. Instrument: Nicolet 6700 Fourier transform infrared spectrometer, Thermo Fisher Scientific. Test conditions: room temperature and pressure; KBr sample pellets were placed in a self-made in-situ cell; scanning range: 400-4000 cm⁻¹. -1 .

[0060] In this embodiment, X-ray fluorescence spectroscopy (XRF) was used. Instrument: ZSX100E X-ray fluorescence spectrometer, manufactured by Rigaku Corporation, Japan. Test conditions: Tested at room temperature after pellet compression, using tungsten-palladium, with an excitation voltage of 40 kV and an excitation current of 250 mA.

[0061] Catalytic performance testing was conducted using an atmospheric pressure fixed-bed reactor, with the aldol condensation of methyl acetate and formaldehyde to synthesize methyl acrylate as the probe reaction. The molar ratio of methyl acetate to formaldehyde was 1:1, methanol was used as the solvent, and the molar ratio of methyl acetate to methanol was 1:2. The feed space velocity of the feed mixture was 1 h⁻¹. -1 The catalyst dosage was 5 g; the carrier gas (N2) flow rate was maintained at 30 mL / min during the reaction, and the reaction temperature was 340 °C. The product was condensed and then subjected to chromatographic analysis.

[0062] Unless otherwise specified, all raw materials used in the examples were purchased commercially and are pure reagents.

[0063] The product analysis methods in the embodiments and comparative examples of this application are as follows:

[0064] The reaction products were analyzed by gas chromatography, and the results were quantified using the external standard method. The chromatographic conditions were as follows: Agilent 6890 chromatograph, HP-5 capillary column, injection volume 0.5 μL, injection port temperature 280℃. Column temperature was maintained at 100℃ for 2 min, then increased to 200℃ at a rate of 15℃ / min and held for 3 min. An FID detector was used, with a detector temperature of 300℃.

[0065] In the embodiments of this application, the conversion rate and selectivity are calculated as follows:

[0066]

[0067]

[0068] Comparative Example 1

[0069] This preparation example illustrates the preparation of TS-1 molecular sieve as a comparison.

[0070] Tetraethyl orthosilicate (TEOS), tetrabutyl titanate [Ti(OBu)4], and tetrapropylammonium hydroxide (TPAOH, 26.5 wt%) solution were mixed at a molar ratio of SiO2:0.01TiO2:0.36TPAOH:35H2O. After stirring for 15 minutes, a clear liquid was obtained. Finally, water was added to the clear liquid, and the mixture was stirred at 348-353 K for about 3 hours to obtain a clear sol. The sol was then crystallized at 443 K for 3 days. The resulting solid was then filtered, washed with distilled water, dried at 373 K for 5 hours, and then calcined at 823 K for 5 hours to obtain TS-1 molecular sieve, designated TS-1-0.01.

[0071] The characterization and evaluation data are shown in Table 1.

[0072] The IR spectrum of sample TS-1-0.01 is shown below. Figure 1 The TS-1 curve and UV-Raman spectrum are shown in the image. Figure 2 The TS-1 curve in the image.

[0073] Comparative Example 2

[0074] This preparation example illustrates the preparation of Cs / SiO2 catalysts.

[0075] Preparation of SiO2: Mix 100 mL of water with tetraethyl silicate at room temperature, add ammonia dropwise to the mixture until pH = 13, stir at 30 °C for 30 min, filter the hydrolyzed silica, dry in a drying oven at 110 °C overnight, cool to room temperature and grind to obtain carrier silica.

[0076] The specific steps for the Cs / SiO2 catalyst are as follows: A certain amount of cesium nitrate was weighed and dissolved in deionized water. Then, 10g of silica was impregnated in deionized water. The molar ratio of cesium to silicon was 0.01, and the molar ratio of silica to solvent was 1:80. The mixture was treated at atmospheric pressure and 25℃ for 1 hour to ensure uniform distribution of cesium ions on the silica. Excess water was evaporated, and the mixture was dried in a drying oven for 6 hours, followed by calcination in a muffle furnace at 400℃ for 6 hours. Characterization and evaluation data are shown in Table 1.

[0077] Example 1

[0078] Example 1 illustrates the alkali-modified titanium-silicon molecular sieve of the present invention and its preparation.

[0079] A certain amount of cesium nitrate was dissolved in deionized water, and then 10g of the molecular sieve TS-1-0.01 prepared in Comparative Example 1 was impregnated. The molar ratio of cesium to silicon was 0.01, and the molar ratio of molecular sieve (based on silica) to solvent was 1:80. The mixture was treated at 1 MPa and 50℃ for 1 h to ensure uniform distribution of cesium ions on the titanium-silicon molecular sieve. Excess water was evaporated, and the mixture was dried in a drying oven at 100℃ for 10 h, followed by calcination in a muffle furnace at 400℃ for 4 h. Characterization and evaluation data are shown in Table 1.

[0080] The IR spectrum of the sample is shown below. Figure 1 The Cs / TS-1 curve and UV-Raman spectrum are shown in [reference]. Figure 2 The Cs / TS-1 curve in the figure.

[0081] Example 2

[0082] Example 2 illustrates the alkali-modified titanium-silicon molecular sieve of the present invention and its preparation.

[0083] A certain amount of cesium nitrate was dissolved in deionized water, and then 10g of the molecular sieve TS-1-0.01 prepared in Comparative Example 1 was impregnated. The molar ratio of cesium to silicon was 0.04, and the molar ratio of molecular sieve (based on silica) to solvent was 1:60. The mixture was treated at 1 MPa and 50℃ for 1.5 h to ensure uniform distribution of cesium ions on the titanium-silicon molecular sieve. Excess water was evaporated, and the mixture was dried in a drying oven at 100℃ for 6 h, followed by calcination in a muffle furnace at 400℃ for 6 h. Characterization and evaluation data are shown in Table 1.

[0084] Comparative Example 3

[0085] This comparative example illustrates the preparation of the TS-1 molecular sieve as a control.

[0086] Tetraethyl orthosilicate (TEOS), tetrabutyl titanate [Ti(OBu)4], and tetrapropylammonium hydroxide (TPAOH, 26.5 wt%) solution were mixed at a molar ratio of SiO2:0.03TiO2:0.36TPAOH:20H2O. After stirring for 15 minutes, a clear liquid was obtained. Finally, water was added to the clear liquid, and the mixture was stirred at 348-353 K for about 3 hours to obtain a clear sol. This sol was then crystallized at 443 K for 3 days. The resulting solid was filtered, washed with distilled water, dried at 373 K for 5 hours, and then calcined at 823 K for 5 hours to obtain a molecular sieve, designated TS-1-0.03. Characterization and evaluation data are shown in Table 1.

[0087] Example 3

[0088] Example 3 illustrates the alkali-modified titanium-silicon molecular sieve of the present invention and its preparation.

[0089] A certain amount of cesium nitrate was dissolved in deionized water, and then 10g of the molecular sieve TS-1-0.03 prepared in Comparative Example 3 was impregnated. The molar ratio of cesium to silicon was 0.02, and the molar ratio of molecular sieve (based on silica) to solvent was 1:30. The mixture was treated at 2 MPa and 70℃ for 3 h to ensure uniform distribution of cesium ions on the titanium-silicon molecular sieve. Excess solvent was evaporated under reduced pressure, and the mixture was dried in a drying oven at 100℃ for 6 h, followed by calcination in a muffle furnace at 450℃ for 4 h. Characterization and evaluation data are shown in Table 1.

[0090] Example 4

[0091] Example 4 illustrates the alkali-modified titanium-silicon molecular sieve of the present invention and its preparation.

[0092] A certain amount of cesium acetate was dissolved in deionized water, and then 10g of the molecular sieve TS-1-0.03 prepared in Comparative Example 3 was impregnated. The molar ratio of cesium to silicon was 0.018, and the molar ratio of molecular sieve (based on silica) to solvent was 1:40. The mixture was treated at 2 MPa and 60℃ for 2 hours to ensure uniform distribution of cesium ions on the titanium-silicon molecular sieve. Excess water was evaporated, and the mixture was dried in a drying oven at 100℃ for 2 hours, followed by calcination in a muffle furnace at 450℃ for 4 hours. Characterization and evaluation data are shown in Table 1.

[0093] Example 5

[0094] Example 5 illustrates the alkali-modified titanium-silicon molecular sieve of the present invention and its preparation.

[0095] A certain amount of cesium nitrate was dissolved in isopropanol, and then 10g of the molecular sieve TS-1-0.03 prepared in Comparative Example 3 was impregnated. The molar ratio of cesium to silicon was 0.015, and the molar ratio of molecular sieve (based on silica) to solvent was 1:50. The mixture was treated at 1.5 MPa and 60℃ for 2 hours to ensure uniform distribution of cesium ions on the titanium-silicon molecular sieve. Excess moisture was evaporated, and the mixture was dried in a drying oven at 100℃ for 6 hours, followed by calcination in a muffle furnace at 400℃ for 6 hours. Characterization and evaluation data are shown in Table 1.

[0096] Comparative Example 4

[0097] Comparative Example 4 illustrates the preparation of a hierarchical porous titanium-silicon molecular sieve (HTS) as a comparison.

[0098] HTS molecular sieves were prepared according to the method described in Example 1 of Chinese Patent CN1301599A, with a titanium-silicon molar ratio of 0.03. Characterization and evaluation data are shown in Table 1.

[0099] Comparative Example 5

[0100] Comparative Example 5 illustrates the preparation of Cs / SBA-15 as a control.

[0101] A certain amount of cesium nitrate was dissolved in deionized water. 10g of SBA-15 molecular sieve was added to the cesium nitrate solution. The molar ratio of cesium to silicon was 0.015, and the molar ratio of molecular sieve (based on silica) to solvent was 1:50. The solution was treated at 1.5 MPa and 60℃ for 2 hours to ensure uniform distribution of cesium ions on the SBA-15 molecular sieve. Excess water was evaporated, and the solution was dried in a drying oven at 110℃ for 6 hours, followed by calcination in a muffle furnace at 400℃ for 6 hours. Characterization and evaluation data are shown in Table 1.

[0102] Example 6

[0103] Example 6 illustrates the alkali-modified titanium-silicon molecular sieve of the present invention and its preparation.

[0104] A certain amount of cesium nitrate was dissolved in water, and then 10g of the HTS molecular sieve prepared in Comparative Example 4 was impregnated with it. The molar ratio of cesium to silicon was 0.015, and the molar ratio of molecular sieve (based on silica) to solvent was 1:50. The mixture was treated at 2 MPa and 60℃ for 2 h to ensure uniform distribution of cesium ions on the titanium-silicon molecular sieve. Excess water was evaporated, and the mixture was dried in a drying oven for 6 h, followed by calcination in a muffle furnace at 400℃ for 6 h. Characterization and evaluation data are shown in Table 1.

[0105] Example 7

[0106] Example 7 illustrates the alkali-modified titanium-silicon molecular sieve of the present invention and its preparation.

[0107] A certain amount of cesium carbonate was dissolved in water, and then 10g of the HTS molecular sieve prepared in Comparative Example 4 was impregnated with it. The molar ratio of cesium to silicon was 0.03, and the molar ratio of molecular sieve (based on silica) to solvent was 1:40. The mixture was treated at 1.5 MPa and 80℃ for 3 h to ensure uniform distribution of cesium ions on the titanium-silicon molecular sieve. Excess water was evaporated under reduced pressure (20 kPa), and the mixture was calcined in a muffle furnace at 400℃ for 6 h. Characterization and evaluation data are shown in Table 1.

[0108] Example 8

[0109] Example 8 illustrates the alkali-modified titanium-silicon molecular sieve of the present invention and its preparation.

[0110] A certain amount of cesium nitrate was dissolved in water, and then 10g of the HTS molecular sieve prepared in Comparative Example 4 was impregnated with it. The molar ratio of cesium to silicon was 0.02, and the molar ratio of molecular sieve (based on silica) to solvent was 1:50. The mixture was treated at 2 MPa and 60℃ for 2 h to ensure uniform distribution of cesium ions on the titanium-silicon molecular sieve. Excess water was evaporated, and the mixture was dried in a drying oven at 110℃ for 6 h, followed by calcination in a muffle furnace at 400℃ for 6 h. Characterization and evaluation data are shown in Table 1.

[0111] Example 9

[0112] Example 9 illustrates the alkali-modified titanium-silicon molecular sieve of the present invention and its preparation.

[0113] A certain amount of cesium nitrate was dissolved in ethanol, and then 10g of the HTS molecular sieve prepared in Comparative Example 4 was impregnated with it. The molar ratio of cesium to silicon was 0.025, and the molar ratio of molecular sieve (based on silica) to solvent was 1:30. The mixture was treated at 2.5 MPa and 70℃ for 3 h to ensure uniform distribution of cesium ions on the titanium-silicon molecular sieve. Excess ethanol was evaporated under reduced pressure (20 kPa), and the mixture was calcined in a muffle furnace at 400℃ for 4 h. Characterization and evaluation data are shown in Table 1.

[0114] Example 10

[0115] Example 10 illustrates the alkali-modified titanium-silicon molecular sieve of the present invention and its preparation.

[0116] A certain amount of cesium nitrate was dissolved in water and then impregnated with 10g of the HTS molecular sieve prepared in Comparative Example 4. The molar ratio of cesium to silicon was 0.022, and the molar ratio of molecular sieve (based on silica) to solvent was 1:50. The mixture was treated at 2 MPa and 60℃ for 2 hours to ensure uniform distribution of cesium ions on the titanium-silicon molecular sieve. Excess water was evaporated, and the mixture was dried in a drying oven at 110℃ for 6 hours, followed by calcination in a muffle furnace at 400℃ for 6 hours. Characterization and evaluation data are shown in Table 1.

[0117] Table 1

[0118]

[0119]

[0120] As can be seen from Table 1, the alkali-modified titanium-silicon molecular sieve of the present invention has good conversion rate and product selectivity in the aldol condensation reaction of methyl acetate and formaldehyde to prepare methyl acrylate. In particular, the types and quantities of by-products are very small. In addition to the main product methyl acrylate, the by-products are acrolein, methacrolein and a small amount of methyl propionate, all of which are valuable compounds.

[0121] The above description is merely a representative embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An alkali metal-modified titanium-silicon molecular sieve, characterized in that, This molecular sieve contains titanium, silicon, oxygen, and alkali metal elements, and is characterized by Raman spectroscopy using a 325 nm light source. At 990 cm⁻¹... -1 A titanium species signal peak is present at 1125±20 cm⁻¹. -1 No obvious titanium species signal peak was observed within the range of 800±20 cm⁻¹. -1 There are molecular sieve framework structure signal peaks within the range, and the intensity is calculated based on the peak area, 990 cm⁻¹. -1 Signal peak intensity and 800±20cm -1 The ratio of signal peak intensity I(990) / I(800) is (1.2-1.3):1; Characterized by IR, 960±20 cm -1 No signal peak was observed; the molecular sieve is a titanium-silicon molecular sieve HTS with a multi-level pore structure and MFI structure; the alkali metal element is cesium.

2. The titanium-silicon molecular sieve according to claim 1, characterized in that, The molar ratio of the alkali metal element to the silicon element in the titanium-silicon molecular sieve is (0.015-0.03):

1.

3. The titanium-silicon molecular sieve according to claim 1, characterized in that, The molar ratio of titanium to silicon is 0.03:

1.

4. A method for preparing alkali metal-modified titanium-silicon molecular sieves according to any one of claims 1-3, characterized in that, The titanium-silicon molecular sieve used as the modifying raw material is mixed with alkali metal cesium hydroxide or alkali metal cesium salt, water and / or organic solvent, and then the water and / or organic solvent are removed. After drying and calcination, the alkali metal modified titanium-silicon molecular sieve is obtained. The titanium-silicon molecular sieve used as the modifying raw material is a hierarchical porous titanium-silicon molecular sieve (HTS). The mixing treatment is carried out at 50-90°C and a gauge pressure of 0.5-5 MPa for 0.5-12 hours.

5. The preparation method according to claim 4, characterized in that, The titanium-silicon molecular sieve used as the modified raw material has a titanium to silicon molar ratio of 0.03:

1.

6. The preparation method according to claim 4, characterized in that, The alkali metal cesium salts are cesium hydrochloride, hypochlorite, chlorite, metachlorite, perchlorate, nitrate, sulfate, bisulfate, sulfite, bisulfite, phosphate, hydrogen phosphate, dihydrogen phosphate, high phosphate, metaphosphate, phosphite, hypophosphate, carboxylate, pyrophosphate, and C1-C cesium salts. 20 One or more of the carboxylates.

7. The preparation method according to claim 4, characterized in that, The alkali metal cesium hydroxide is cesium hydroxide, and the alkali metal cesium salt is selected from one or more of cesium nitrate, cesium carbonate, cesium bicarbonate, and cesium acetate.

8. The preparation method according to claim 4, characterized in that, The molar ratio of the titanium-silicon molecular sieve, alkali metal cesium hydroxide or alkali metal salt, water and / or organic solvent used as the modified raw material is 1:(0.001-0.1):(10-100), wherein the titanium-silicon molecular sieve used as the modified raw material is calculated as SiO2, and the alkali metal cesium hydroxide or alkali metal cesium salt is calculated as alkali metal.

9. The preparation method according to claim 4, characterized in that, The organic solvent is selected from C1-C6. 10 alcohols, C3-C 10 Ketones, C2-C 10 Ester.

10. The preparation method according to claim 4, characterized in that, The gauge pressure is 0.5-4 MPa.

11. The preparation method according to claim 10, characterized in that, The gauge pressure is 0.8-3 MPa.

12. The preparation method according to claim 11, characterized in that, The gauge pressure is 1.2-2.5 MPa.

13. A catalyst containing titanium-silicon molecular sieves, characterized in that, The catalyst contains either the alkali metal-modified titanium-silicon molecular sieve as described in any one of claims 1-3 or the alkali metal-modified titanium-silicon molecular sieve prepared by the preparation method described in any one of claims 4-12.

14. The catalyst according to claim 13, characterized in that, The alkali metal-modified titanium-silicon molecular sieve accounts for 5%-100% of the catalyst by weight.

15. A method for preparing a carbonyl-containing compound, wherein a carbonyl-containing compound having α-H undergoes a carbon-carbon coupling reaction with another carbonyl-containing compound in the presence of a catalyst to generate a carbonyl-containing compound having β-hydroxyl groups or a carbonyl-containing compound having α,β-unsaturated bonds, characterized in that, The catalyst is the catalyst described in claim 13 or 14.

16. The method according to claim 15, characterized in that, This is due to the aldol condensation reaction between methyl acetate and formaldehyde.

17. The method according to claim 16, characterized in that, Aldol condensation reaction conditions The reaction includes: a methyl acetate to formaldehyde molar ratio of 1:2 to 5:1, methanol as the solvent, a methanol to methyl acetate molar ratio of 1:1 to 2:1, a reaction temperature of 320 to 400°C, a reaction gauge pressure of 0 to 1 MPa, a nitrogen flow rate of 30 to 100 mL / min, and a liquid hourly space velocity of 0.1 to 2 h⁻¹. -1 .

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