Silicon powder as well as preparation method and application thereof

Abstract

The invention relates to silicon powder as well as a preparation method and application thereof. In an ultraviolet Raman spectrum of the silicon powder, no characteristic peak exists near 240 cm <-1 >; or, in the ultraviolet Raman spectrum of the silicon powder, in a characteristic region with the vibration frequency not larger than 600 cm <-1 >, at least one characteristic peak not larger than 240 cm <-1 > exists, and the sum of the peak areas of the characteristic peaks not larger than 240 cm <-1 > accounts for more than or equal to 20% of the total area of the characteristic peaks in the characteristic region with the vibration frequency not larger than 600 cm <-1 >. The silicon powder disclosed by the invention can be applied to synthesis of a silicon-containing crystalline state material, and has the characteristics of good uniformity, easiness in activation and crystallization, low dependence on an organic template agent, shortening of a crystallization induction period and the like.

Description

Technical Field

[0001] The invention belongs to the field of silicon powder materials, and specifically relates to silicon powder and a preparation method thereof and application thereof in preparing silicon-containing crystalline materials. Background Art

[0002] The properties and functions of the material are closely related to its multi-level condensed structure. It is crucial to improve the synthesis efficiency (high crystallinity) and construct rich surface properties (acid distribution) through the optimization of the synthesis process. Zeolite molecular sieves are a type of crystalline aluminosilicates with molecular pores or cages formed by sharing the vertices of silicon and aluminum tetrahedrons (or other elements such as boron). Among them, high-silicon molecular sieves have the functions of ion exchange, shape-selective catalysis, and molecular sieving, and are widely used in the fields of petroleum refining, petrochemicals, and the synthesis of fine or specialty chemicals. In order to achieve the effectiveness of the construction of microporous materials and synthesize long-range ordered high-silicon molecular sieve crystal materials, the main measure is to encourage more silicon atoms to enter the framework in an appropriate coordination form, which puts higher requirements on the silicon source.

[0003] In 1961, Professor Barrer first used organic ammonium ions to replace alkali / alkaline earth metals (Journal of the Chemical Society, 1961, 971-982.) to synthesize high-silicon molecular sieves, promoting the activation of silicon atoms and effectively entering the molecular sieve framework; subsequently, the American Mobil Company achieved a milestone breakthrough in the synthesis and development of high-silicon ZSM-5. After decades of development, researchers generally agree that this type of quaternary ammonium base can effectively promote the high crystallinity of silicon-containing molecular sieves, improve the utilization rate of silicon sources, expand the adjustable range of silicon-aluminum ratio, and make the crystal size more controllable. Through activation energy calculation, it is found that organic templates play a comprehensive role in the directional synthesis of molecular sieves, significantly reducing the crystallization barrier, and filling the pores to stabilize the structure, charge balance matching, etc. However, organic templates are usually expensive, and the high template-silicon ratio of high-silicon synthesis limits its application and development, and is bound to cause the discharge of a large amount of organic wastewater in industrial production. Green synthesis is a new hot spot proposed in recent years. With the global attention to environmental protection, replacing or reducing the use of templates has become a common goal of researchers. Among them, Professor Avelino Corma combined the dry gel conversion DGC method to find that the fluorine-containing high-concentration system has great value and potential in the field of efficient synthesis of molecular sieves. Fluoride can promote the mineralization and activation of silicon sources into the ability of crystallized perfect molecular sieve frameworks (Topics in Catalysis, 1999, 9: 59-76.); However, due to problems such as crystallization efficiency and engineering amplification, the introduction of fluorine also increases the requirements for production equipment and certain environmental pressures. At the same time, fluorine will lead to a sharp decrease in terminal silanol groups, affecting the acid catalytic performance of synthetic molecular sieve products. Academician Yu Jihong's team used hydroxyl radicals to achieve Coulomb stabilization of the liquid phase, accelerated the zeolite crystallization process, improved the synthesis efficiency, and improved people's understanding of the crystallization mechanism of zeolite materials (Science, 2016, 351: 1188-1191.); However, there are still some problems that have not been well solved. Hydroxyl radicals need to be excited by ultraviolet irradiation or Fenton reaction, which is difficult to achieve in industrial production.

[0004] To The catalytic activity of the positive carbon ion reaction with acid as the active center increases with the increase of the zeolite silicon-aluminum ratio within a certain range; however, the thermodynamic process of sol-gel hydrothermal formation of ionic silicon clusters conforms to the LOWE equilibrium model, and the difficulty of effective activation (decomposition, crystallization and recombination) of silicon sources also increases with the increase of the silicon-aluminum ratio. At present, the method of inducing silicon species nucleation and promoting the growth of high crystallinity of molecular sieves, in addition to adding expensive organic templates, common methods of adding directing agent solutions or seeds, etc. can promote nucleation; however, auxiliary synthesis methods such as seeds, etc., have not been greatly changed in the efficiency and controllability of the entire synthesis process. The molecular sieve secondary structure unit SBU (Microporous & Mesoporous Materials, 2012, 156: 181-188.) is changed by the coordination of heterogeneous metals, but impurity elements will be introduced. Professor Wu Peng and others reported a reconstruction synthesis method (Wu Peng, Zhu Zhiguo, Wu Haihong, He Mingyuan. ZL2016108264030), which obtained an active silicon source through a series of processes such as high-temperature roasting and deep acid hydrolysis. This method upgraded the effect of seed synthesis, but the process is relatively cumbersome and harsh, and the silicon obtained is not 100% pure. Usually, in order to achieve the formation of "silanol nests" (pore wall and surface framework defects, silanol nests) in zeolites, Professor Ryong Ryoo's research group believes that complex and efficient organic molecules are still needed to overcome energy barriers to form stable coordination bonds (Nature, 2020, 585, 221-224.). At present, various methods for activating silicon sources have their own characteristics, and their performance is also improving day by day, but compared with the high efficiency, environmental protection and controllability requirements of industrial production, the above methods still have shortcomings.

[0005] In view of this, there is an urgent need to develop a method for obtaining an efficient activated silicon source through a simple and controllable pretreatment, to regulate the nucleation and growth dynamics of subsequent silicon-containing crystalline materials, to construct a charge density concentrated environment for the system under more environmentally friendly process conditions such as a low mode silicon ratio, and to achieve the goal of uniform high dispersion and high crystallinity of long-range ordered silicon-containing crystalline materials (such as titanium silicon molecular sieves, silicon aluminum molecular sieves, germanium silicon molecular sieves or pure silicon porous materials, etc.). Summary of the invention

[0006] In view of the above background, one of the purposes of the present invention is to solve the problem of insufficient activity of silicon source (silicon powder) and difficulty in efficient crystallization in the prior art. Another purpose of the present invention is to provide a preparation method to solve the problem of poor crystallization activity of conventional silicon sources, and the obtained solid silicon powder product can be characterized by solid nuclear magnetic resonance, ultraviolet Raman spectroscopy (UV-Raman) and infrared spectroscopy to identify the formation of structural units.

[0007] For example, one of the purposes of the present invention is to provide a silicon powder that can be used in the synthesis of silicon-containing crystalline materials, and has the characteristics of easy activation and crystallization, low dependence on organic templates, and shortened crystallization induction period. For another example, the second purpose of the present invention is to provide a preparation method corresponding to the above silicon powder, using common silicon-containing substances as the initial raw materials, and the process adopts The treatment forms such as process, pseudo-foam alkalization or controlled oligomerization highlight the dissolution and mineralization of silicon species by inorganic (OH-, F-, etc.) or organic anions to form rich surface silicon hydroxyl species, and solve the problem of poor crystallization activity of conventional silicon sources through simple and controllable pretreatment methods.

[0008] In order to achieve the above object, the first aspect of the present invention provides a silicon powder, wherein in the ultraviolet Raman spectrum of the silicon powder, at a vibration frequency of 240cm -1 There are characteristic peaks nearby, with a vibration frequency no greater than 600cm -1 In the characteristic area, there is at least one non-240cm -1 Characteristic peaks near 240cm -1 The sum of the peak areas of the nearby characteristic peaks is no more than 600 cm -1 The total area of ​​the characteristic peaks in the characteristic region is ≥ 20% but not more than 98% (correspondingly, at 240 cm -1 The area of ​​the characteristic peaks near the -1 The total area of ​​characteristic peaks in the characteristic region is ≤80%).

[0009] In some embodiments of the present invention, in the ultraviolet Raman spectrum of the silicon powder, at a vibration frequency of no more than 600 cm -1 In the characteristic region, there is a vibration frequency of 335cm -1 、400cm -1 and 480cm -1 At least one characteristic peak in the vicinity.

[0010] In the present invention, the peak area of ​​each characteristic peak can be obtained by automatic (or manual if necessary) integration in a spectrometer. The present invention does not limit the specific peak area of ​​each characteristic peak. -1 The peak area of ​​the characteristic peaks near 240 cm -1 The relationship between the areas of nearby characteristic peaks has corresponding limitations.

[0011] The silicon powder in the present invention is a silicon powder containing structural units, and the structural unit in "silicon powder containing structural units" refers to a silicon-containing four-membered ring (4MR), five-membered ring (5MR) or six-membered ring (6MR) that can constitute the molecular sieve framework structure.

[0012] According to the present invention, 240cm -1The characteristic peak near is the characteristic signal of TOT bending vibration of silicon-containing eight-membered ring (8MR). When the ultraviolet Raman spectrum of the silicon powder is at 240cm -1 When there is a characteristic peak nearby, it means that the silicon atoms in the silicon powder have overcome the skeleton stress and formed more active structural units of the aforementioned 4MR, 5MR or 6MR.

[0013] According to the present invention, in the ultraviolet Raman spectrum of silicon powder, 240cm -1 The characteristic peaks near the 8-membered ring (8MR) represent the bending vibration of TOT in the silicon-containing 8-membered ring; the vibration frequency is not more than 600 cm -1 In the characteristic region, the smaller rings correspond to higher vibration frequencies, not 240 cm -1 Among the characteristic peaks nearby, 335cm -1 、400cm -1 or 480cm -1 The characteristic peaks near 240cm represent the bending vibration of TOT in the six-membered ring (6MR), five-membered ring (5MR) and four-membered ring (4MR) containing silicon. -1 The sum of the peak areas of the nearby characteristic peaks is no more than 600 cm -1 The total area of ​​the characteristic peaks in the characteristic region is ≥20% but not more than 98%, indicating that the silicon atoms in the silicon powder have more active structural units such as four-membered rings (4MR), five-membered rings (5MR) or six-membered rings (6MR).

[0014] In some embodiments of the present invention, in the ultraviolet Raman spectrum of the silicon powder, at a vibration frequency of no more than 600 cm -1 In the characteristic area, non-240cm -1 The characteristic peak near is 335cm -1 、400cm -1 and 480cm -1 At least one of the nearby characteristic peaks.

[0015] In some embodiments of the present invention, at a vibration frequency of no more than 600 cm -1 In the characteristic area, non-240cm -1 The characteristic peak near 335cm -1 、400cm -1 and 480cm -1 The sum of the peak areas of at least one of the characteristic peaks nearby is no more than 600 cm -1 The total area of ​​characteristic peaks in the characteristic region is ≥50%.

[0016] Regarding the expression “near” in the above content, those skilled in the art will know that since each characteristic peak in the ultraviolet Raman spectrum usually has a displacement, the position of the characteristic peak defined in the present invention may have a deviation, such as 480cm -1 The nearby characteristic peak is at 450cm -1 ~500cm -1 However, the vibration represented by each characteristic peak can be determined by those skilled in the art.

[0017] In the present invention, the above-mentioned “no more than 600cm -1 The characteristic area generally refers to 200cm -1 ~600cm -1 Those skilled in the art will understand that if a characteristic peak appears in a region of silicon powder where it is not easy to have a characteristic peak, it should be verified whether it is an impurity peak formed by contamination.

[0018] In some embodiments of the present invention, the specific surface area of ​​the silicon powder is 200m 2 / g~980m 2 / g, preferably 550m 2 / g~980m 2 / g.

[0019] In some embodiments of the present invention, the mass fraction of SiO2 in the silicon powder is >90%, preferably >95%, and more preferably >98%.

[0020] In some embodiments of the present invention, the pore volume of the silicon powder is 0.2 cm 3 / g~3.0cm 3 / g.

[0021] The second aspect of the present invention provides a method for preparing the silicon powder according to the first aspect, comprising the following steps:

[0022] S1, providing a mixed solution I containing a treatment reagent and a solvent I;

[0023] S2, mixing the silicon-containing raw material with the mixed solution I to obtain a mixed solution II;

[0024] S3, performing activation treatment on the mixed solution II to obtain an activated product;

[0025] S4, calcining the activated product to obtain the silicon powder.

[0026] In some embodiments of the present invention, in step S1, the treatment reagent is selected from at least one of an inorganic base, a fluorine-containing substance, an organic base and an ionic liquid containing an organic anion; preferably at least one of ammonia water, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, hydrofluoric acid, sodium fluoride, ammonium fluoride, silicon tetrafluoride, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide and 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF6).

[0027] In the present invention, 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF6) is an imidazole-type ionic liquid.

[0028] In the present invention, the treatment reagent is preferably an organic quaternary ammonium base or fluoride, that is, at least one selected from hydrofluoric acid, sodium fluoride, ammonium fluoride, silicon tetrafluoride, tetramethylammonium hydroxide, tetraethylammonium hydroxide and tetrapropylammonium hydroxide.

[0029] In the present invention, when used, the treatment reagent is usually prepared into a solution of a certain concentration using water or alcohol as a solvent. For example, the organic base can be prepared into an aqueous solution or an alcohol solution. Those skilled in the art can make a selection based on actual conditions.

[0030] In some embodiments of the present invention, in step S1, the solvent I is selected from at least one of water, alcohols and ionic liquids; preferably at least one of deionized water, methanol, ethanol, n-butanol, isopropanol, ethylene glycol and 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF6).

[0031] In some embodiments of the present invention, in step S2, the silicon-containing raw material is selected from at least one of diatomaceous earth, water glass, (liquid) silica sol, white carbon black, gas-phase silica sol, silicon powder, silicone resin microspheres, silicates (such as tetramethyl silicate, tetraethyl silicate or tetrapropyl silicate), silicon tetrachloride and silane; wherein the silane is preferably selected from at least one of tetramethylsilane Si(CH3)4, methyltrimethoxysilane MTMS, isobutylene triethoxysilane, trichlorosilane SiHCl3 and tetraethoxysilane Si(OC2H5)4.

[0032] In the present invention, the silicon-containing raw material is preferably liquid silica sol, silicate or silane.

[0033] In the present invention, the optional silicon-containing raw materials mentioned above are all silicon-containing materials commonly used in the art.

[0034] In some embodiments of the present invention, the molar ratio of the treatment reagent to SiO2 in the silicon-containing raw material (hereinafter referred to as the treatment reagent / SiO2 molar ratio) is 0.0001 to 10:1, preferably 0.0001 to 0.1:1.

[0035] In some embodiments of the present invention, the molar ratio of the solvent I to SiO2 in the silicon-containing raw material (hereinafter referred to as the solvent I / SiO2 molar ratio) is 0.5 to 50:1.

[0036] In some embodiments of the present invention, the molar ratio of the total hydroxide anions in the treatment reagent and the solvent I to the SiO2 in the silicon-containing raw material (hereinafter referred to as OH - / SiO2 molar ratio) is 2 to 60:1.

[0037] In some embodiments of the present invention, in step S2, the conditions for the mixing treatment include: a stirring speed of 0 to 5000 rpm, preferably 0 to 50 rpm; and a temperature of 0 to 50°C, preferably 5 to 30°C.

[0038] In some embodiments of the present invention, in step S3, the process for performing the activation treatment (also referred to as the gelling process) is selected from The method comprises at least one of the following steps: preparing monodisperse SiO2 microspheres by alkaline hydrolysis of tetraethyl orthosilicate (TEOS), hydrolysis, oligomer precipitation, alkaline dissolution and hot melting to highlight the mineralization effect on silicon atoms.

[0039] The activated The process includes mixing and hydrolysis steps; the hydrolysis step of the activation treatment is mainly controlled by controlling the hydrolysis catalyst (promoter or inhibitor) and temperature, stirring / ultrasound / irradiation, time and other parameters; the oligomer precipitation of the activation treatment includes the steps of hydrolysis, solvent network bonding and growth; the alkali dissolution of the activation treatment includes adding a certain amount of ammonia water, sodium hydroxide or potassium hydroxide solution with a certain concentration into the above preparation process; the hot melt of the activation treatment refers to a single-stage or segmented high-temperature heat treatment at 300-1000°C for a certain period of time.

[0040] In the present invention, the activation treatment preferably uses an optimized Specifically, the hydrolysis, bonding and SiO2 growth rates can be controlled by the amount of solvent, temperature and stirring speed to achieve uniformity and controllability of silicon powder.

[0041] According to the present invention, The process, hydrolysis, oligomer precipitation, alkali dissolution and hot melting are all conventional methods of the present invention. The present invention does not strictly limit the various parameters involved in the process, and those skilled in the art can determine them according to actual conditions.

[0042] In some embodiments of the present invention, the conditions for activation treatment include: temperature not higher than 200°C (such as 0-200°C), preferably not higher than 100°C (such as 0-100°C); treatment time is 1 hour to 500 days, preferably 12 hours to 12 days; further preferably, the activation treatment is completed at a temperature of 0-10°C, a temperature of 10-30°C, a temperature of 30-80°C, and a temperature of 80-100°C (segmented constant temperature heat treatment) for 0 to 120 hours (such as 1 to 120 hours).

[0043] In some embodiments of the present invention, after obtaining the activated product of step S3, before the calcination treatment of step S4, the activated product can also be subjected to impurity removal treatment, and water-soluble impurities and solvents, including all impurities such as physically adsorbed water, alcohols, salts and ionic liquids, can be removed by means of forced air drying, vacuuming, etc. At the same time, a maximum of Si, C, H, O, F, S, Br, Cl or MoO can be retained at the same time. x At least one composition.

[0044] In some embodiments of the present invention, in step S4, the conditions for the calcination treatment include: a temperature of 150 to 1000°C, preferably 400 to 600°C; a time of 0.05 to 500 hours; further preferably, within the temperature range of 150 to 1000°C (preferably 400 to 600°C), at least two calcination temperatures are selected from low to high in an air atmosphere and calcined for 0.05 to 2 hours respectively, for example, in an air atmosphere, calcined at 150 to 200°C, 250 to 350°C, 400 to 500°C, and 500 to 600°C in sequence for 0.05 to 2 hours.

[0045] In some embodiments of the present invention, during the calcination treatment, a programmed temperature increase of 0.5 to 5° C. / min is used to raise the temperature from room temperature to the calcination temperature (ie, 150 to 1000° C., preferably 400 to 600° C.).

[0046] In the present invention, the calcination treatment is used to remove the skeleton crystal water (the desorption temperature is usually ≥ 200°C at normal pressure), sublimable fluoride, sulfur or MoO x Impurities such as alkali or salt molecules of the organic template can be completely decomposed by high temperature oxidation.

[0047] The third aspect of the present invention provides an application of the silicon powder as described in the first aspect and / or the silicon powder prepared by the preparation method as described in the second aspect in the preparation of silicon-containing crystalline materials, especially in the preparation of titanium silicon molecular sieve, silicon aluminum molecular sieve, germanium silicon molecular sieve or pure silicon porous material. That is, the silicon-containing crystalline material is preferably titanium silicon molecular sieve, silicon aluminum molecular sieve, germanium silicon molecular sieve or pure silicon porous material; the silicon-containing crystalline material is further preferably at least one of TS-1 molecular sieve, β molecular sieve, ZSM-5 molecular sieve, EU-1 molecular sieve, MCM-22 molecular sieve, SCM-4 molecular sieve, Solicalite-2 molecular sieve, mordenite molecular sieve, intergrowth zeolite molecular sieve and SBA-15 molecular sieve.

[0048] According to the present invention, after the silicon-containing crystalline material is synthesized using the silicon powder, the silicon-containing crystalline material (catalytic material) can be used in a highly efficient catalytic carbonium ion reaction.

[0049] In the present invention, when preparing and synthesizing silicon-containing crystalline materials (such as molecular sieves), the synthesis methods of silicon-containing crystalline materials of different configurations are different, and the silicon powder of the present invention can be applied. As for the amount of silicon powder used, those skilled in the art can add an appropriate amount according to different requirements of the target product.

[0050] According to the present invention, after the silicon powder is used to synthesize the silicon-containing crystalline material, the nucleation induction period of the obtained silicon-containing crystalline material at a temperature below 100° C. is less than 24 hours.

[0051] Compared with the prior art, the present invention has the following beneficial effects:

[0052] (1) The silicon powder provided by the present invention overcomes the structural stress of forming structural units, has abundant silicon-containing four-membered rings (4MR), five-membered rings (5MR) or six-membered rings (6MR), has a large pore volume and specific surface area, and can thus significantly shorten the nucleation induction period. As an active raw material, it can be efficiently used in the synthesis process of silicon-containing crystalline materials;

[0053] (2) The method for preparing silicon powder provided by the present invention solves the problem of efficient preparation of silicon powder containing structural units. The key to the technology lies in the control of the pretreatment process. The preparation process avoids the use of excessive water or non-circulating organic matter and can be used for industrial production.

[0054] (3) The silicon powder containing the structural unit of the present invention can be used for the synthesis of silicon-containing crystalline materials, especially for the synthesis of titanium silicon molecular sieve, silicon aluminum molecular sieve, germanium silicon molecular sieve or pure silicon porous material, and can shorten the crystallization induction period. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] The present invention will be further described in detail below in conjunction with the accompanying drawings.

[0056] Figure 1 TEM photo of silicon powder SG1 containing structural units prepared in Example 1 of the present invention is shown;

[0057] Figure 2 The UV-Raman spectra of silicon powder SG1 and white carbon black A200 containing structural units prepared in Example 1 of the present invention are shown;

[0058] Figure 3 The nitrogen low temperature adsorption-desorption (BET) curves of silicon powder SG1 and white carbon black A200 containing structural units prepared in Example 1 of the present invention are shown;

[0059] Figure 4 The FT-IR spectra of silicon powder SG1 and white carbon black A200 containing structural units prepared in Example 1 of the present invention are shown.

[0060] Figure 5 The crystallization kinetic curves of the β molecular sieve products prepared in Example 47 of the present invention and Comparative Example 1 are shown. DETAILED DESCRIPTION

[0061] In order to make the present invention easier to understand, the present invention will be described in detail below with reference to embodiments and drawings. These embodiments are only for illustration and are not intended to limit the application scope of the present invention.

[0062] In the present invention, the specific surface area and pore volume are analyzed by low-temperature N2 adsorption-desorption analysis of the samples using a Tristar3000 specific surface analyzer produced by Micrometrics. The samples are pretreated at 300°C for 6 hours by vacuum activation before testing. The test temperature is -196°C. The pore structure data such as the specific surface area and pore volume of the test samples are obtained by analyzing the isotherms.

[0063] In the present invention, the mass fraction of SiO2 in silicon powder is measured by thermogravimetric TG-DTA analysis of samples using a TGA Q500analyzer instrument (test conditions are air atmosphere, heating rate 10°C / min). In the following examples, the chemical reagents used are all commercially available products, and no special purification treatment is performed unless otherwise specified.

[0064] In the present invention, the FT-IR spectrum test uses a Nexus670 Fourier transform infrared spectrometer (FT-IR) produced by Nicolet Company of the United States to analyze the skeleton vibration area of ​​the sample; during the test, the sample powder is first diluted with KBr to a mass fraction of about 3%, ground and mixed evenly with a mortar, and then pressed into a tablet to prepare a sample, which is then placed in a vacuum cell for testing, and the test resolution is 4cm- 1 , scanning times 32 times, test range 400~4000cm -1 .

[0065] Example 1

[0066] Weigh sodium hydroxide, sodium fluoride, and 25% ammonia solution, add them to deionized water to dissolve evenly, add methanol, and place the solution in a 5°C water bath; weigh methyltrimethoxysilane, add it evenly to the above solution while stirring at 30rpm, stir for another 2 minutes, transfer it to a container and let it stand at 30°C for 5 hours to obtain a sol, and rotary evaporate the solvent under vacuum conditions at 80°C until a solid block is precipitated. Among them, the molar ratio of treatment reagent / SiO2 is 0.05; the molar ratio of solvent I / SiO2 is 10; OH - / SiO2 molar ratio 10.

[0067] The solid block obtained in the above preparation was treated with 1% citric acid aqueous solution at a liquid-solid mass ratio of about 6:1, and then acid exchanged at 80°C for 1.5 hours, washed with deionized water until electrically neutral, and dried at 120°C. The temperature was then raised to 600°C at a rate of 3°C / min, and calcined at a constant temperature for 1.5 hours to obtain sample SG1.

[0068] The specific surface area of ​​sample SG1 is S BET 510m 2 / g, pore volume = 2.4 cm 3 / g, SiO2 mass fraction is 99%, Figure 2 It can be seen that compared with silica A200, sample SG1 has a vibration frequency of no more than 600 cm -1 There are more non-240cm areas in the characteristic area -1 Nearby characteristic peaks; UV-Raman detected its vibration frequency at 335cm -1 、400cm -1 and 480cm -1 The peak area of ​​the characteristic peak near 240cm -1 Characteristic peaks near 240cm -1 The sum of the peak areas of the nearby characteristic peaks is no more than 600 cm -1 The total area of ​​the characteristic peaks in the characteristic region is 78%. Figure 2 In the UV-Raman spectrum of sample SG1, due to peak overlap, 335cm -1 、400cm -1 and 480cm -1 Nearby characteristic peaks overlap.

[0069] Depend on Figure 1 It can be seen that the silicon oxide particles in sample SG1 are uniform and dispersed; Figure 3 It can be seen that compared with silica A200, sample SG1 has a larger low-temperature adsorption capacity for nitrogen, and the specific surface area and pore volume obtained from the curve are larger; Figure 4 It can be seen that the signal peak of silanol in the corresponding FT-IR spectrum of sample SG1 is stronger (usually, the larger the peak area at the characteristic position, the higher the surface silanol concentration of the sample).

[0070] Example 2-15

[0071] The preparation methods of Examples 2 to 15 are basically the same as those of Example 1 (including but not limited to the molar ratio of treatment reagent / SiO2, the molar ratio of solvent I / SiO2 and the molar ratio of OH). - / SiO2 molar ratio), the difference lies in the selection of different silicon-containing raw materials, processing reagents and solvent I, the specific preparation conditions are shown in Table 1 below, the samples are marked as SG2~SG15 in sequence, and the performance parameter information of samples SG2~SG15 is shown in Table 2 below; the peak area ratio of each characteristic peak detected by UV-Raman of samples SG2~SG15 is shown in Table 5 below.

[0072]

[0073]

[0074]

[0075] Examples 16-25

[0076] The preparation methods of Examples 16 to 20 are basically the same as those of Example 8 (including but not limited to raw materials, steps, etc.), except that the molar ratio of the treating reagent / SiO2, the molar ratio of the solvent I / SiO2, and the OH - / SiO2 molar ratio and treatment process selection, the specific preparation conditions are shown in Table 2 below, and the samples are marked as SG16 to SG20 in sequence;

[0077] The preparation methods of Examples 21 to 25 are basically the same as those of Example 9 (including but not limited to raw materials, steps, etc.), except that the molar ratio of the treating agent / SiO2, the molar ratio of the solvent I / SiO2, and the OH - / SiO2 molar ratio and treatment process selection, the specific preparation conditions are shown in Table 3 below, and the samples are marked as SG21 to SG25 in sequence;

[0078] The performance parameter information of samples SG16 to SG25 is shown in Table 4 below;

[0079] The peak area ratios of the characteristic peaks detected by UV-Raman for samples SG16 to SG25 are shown in Table 5 below.

[0080]

[0081]

[0082]

[0083] UV-Raman detection shows that samples SG02~SG25 have a non-240cm -1 The sum of the peak areas of the nearby characteristic peaks is no more than 600 cm -1 The total area of ​​characteristic peaks in the characteristic region is ≥50%, as shown in Table 5 below:

[0084] Table 5

[0085]

[0086]

[0087] Embodiment 26

[0088] This embodiment is substantially the same as embodiment 18, except that after obtaining the precipitated solid, the subsequent preparation method is as follows:

[0089] Take the solid block obtained by the above preparation, use 3% ammonium nitrate aqueous solution, liquid-solid mass ratio of about 4:1, exchange activation treatment at 90°C for 60 minutes, wash with deionized water until electrically neutral, and dry at 100°C. Then increase the temperature to 500°C at 2°C / min, and high-temperature roasting treatment for 3 hours. Sample SG26 is obtained.

[0090] The specific surface area of ​​sample SG26 is S BET 570m 2 / g, pore volume is 2.4cm 3 / g, SiO2 mass fraction is 98%, UV-Raman detection of its vibration frequency is 480cm -1 The characteristic peak area is greater than that at 240 cm -1 Nearby characteristic peaks.

[0091] Examples 27-36

[0092] Examples 27 to 36 were prepared in accordance with the preparation methods of Examples 16 to 25 to obtain solid blocks (i.e., Example 27 was prepared in accordance with Example 16, Example 28 was prepared in accordance with Example 17, and so on); and subsequent preparation was performed in accordance with Example 26, except that the calcination activation conditions were different. The specific preparation conditions are shown in Table 6. The obtained samples were marked as SG27 to SG36 in turn. The performance parameter information of samples SG27 to SG36 is shown in Table 7 below;

[0093]

[0094]

[0095]

[0096] Examples 37-46

[0097] Examples 37 to 41 are: using samples SG18 to SG22 obtained in Examples 18 to 22, the silicon-containing crystalline materials are synthesized by a hydrothermal crystallization synthesis method to obtain samples SG37 to SG41.

[0098] Examples 42 to 46 are: using samples SG30 to SG34 obtained in Examples 30 to 34, silicon-containing crystalline materials are synthesized by a hydrothermal crystallization synthesis method to obtain samples SG42 to SG46.

[0099] Taking Example 38 as an example: Sodium aluminate and the sample SG1 obtained in Example 1 were used as the main raw materials for the synthesis, TEAOH / TEABr was used as OSDA, and the ratio of 0.55TEA + :1SiO2:10H2O:1 / 55Al2O3 is formed into gel, the above gel liquid is transferred into a tetrafluoroethylene-lined pressure bomb, hydrothermally synthesized at a crystallization temperature of 165°C for 100 hours, naturally cooled to below 40°C in air, filtered and cleaned, and dried at 120°C for 12 hours to obtain a solid product (β molecular sieve), marked as sample SG47.

[0100] According to the kinetic curve of the crystallization process, the nucleation induction period time results of the above samples SG37~SG46 at 90°C were measured, as shown in Table 8 below; wherein, the drawing standard of the kinetic curve of the crystallization process is: take samples after different crystallization times, use the XRD characterization results of the same molecular sieve configuration standard sample as a unified reference, and according to the percentage data of the relative crystallinity of the sample reaching the benchmark sample (the sum of the areas of the XRD characteristic peaks under the same test conditions), the crystallization time consumed by the sample at this time is used as the X-axis, and the data points are plotted to obtain the crystallization kinetic curve, and the rapid rising section of the curve is made into a tangent, and the time point where the tangent intersects the X-axis is the nucleation induction period time of the molecular sieve sample.

[0101]

[0102] Comparative Example 1

[0103] Commercially available white carbon black A200 (vibration frequency 240 cm in UV Raman spectrum) was used. -1 There is no characteristic peak near the surface of the silicon-containing crystalline material by a hydrothermal crystallization synthesis method to obtain a β molecular sieve. The specific steps are as follows:

[0104] Sodium aluminate and commercially available white carbon black A200 (with a vibration frequency of 240 cm in the ultraviolet Raman spectrum) were used for the synthesis. -1There is no characteristic peak nearby) as the main raw material, TEAOH / TEABr as OSDA, and 0.55TEA + :1SiO2:10H2O:1 / 55Al2O3 is formed into a gel solution, which is transferred into a tetrafluoroethylene-lined pressure bomb and hydrothermally synthesized at a crystallization temperature of 165°C for 160 hours. It is then naturally cooled to below 40°C in air, filtered and cleaned, and dried at 120°C for 12 hours to obtain a solid product (β molecular sieve), which is marked as sample D1.

[0105] The crystallization kinetic curves of the sample SG38 obtained in comparison with the sample D1 described above ( Figure 5 ), it can be seen that the induction period of the β molecular sieve described in Example 38 (L-β) of the present invention is 8h, and the induction period of the β molecular sieve described in Comparative Example 1 (D-β) is 45h.

[0106] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation to the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein, on the contrary, the present invention can be extended to all other methods and applications with the same functions.

Claims

1. A silicon powder, wherein in the ultraviolet Raman spectrum of the silicon powder, at a vibration frequency of 240cm -1 There are characteristic peaks nearby, with a vibration frequency no greater than 600cm -1 In the characteristic area, there is at least one non-240cm -1 Characteristic peaks near 240cm -1 The sum of the peak areas of the nearby characteristic peaks is no more than 600 cm -1 The characteristic peak area of ​​the characteristic region accounts for 20% to 98% of the total area.

2. The silicon powder according to claim 1, characterized in that In the ultraviolet Raman spectrum of the silicon powder, the vibration frequency is not greater than 600cm -1 In the characteristic region, there is a vibration frequency of 335cm -1 、400cm -1 and 480cm -1 At least one characteristic peak in the vicinity.

3. The silicon powder according to claim 1 or 2, characterized in that: At a vibration frequency of no more than 600 cm -1 In the characteristic area, non-240cm -1 The sum of the peak areas of the nearby characteristic peaks is no more than 600 cm -1 The total area of ​​characteristic peaks in the characteristic region is ≥50%.

4. The silicon powder according to any one of claims 1 to 3, characterized in that The specific surface area of ​​the silicon powder is 200m 2 / g~980m 2 / g; And / or, in the silicon powder, the mass fraction of SiO2 is greater than 90%; And / or, the pore volume of the silicon powder is 0.2 cm 3 / g~3.0cm 3 / g.

5. A method for preparing silicon powder according to any one of claims 1 to 4, comprising the following steps: S1, providing a mixed solution I containing a treatment reagent and a solvent I; the treatment reagent is selected from at least one of an inorganic base, a fluorine-containing substance, an organic base and an ionic liquid containing an organic anion; S2, mixing the silicon-containing raw material with the mixed solution I to obtain a mixed solution II; S3, performing activation treatment on the mixed solution II to obtain an activated product; S4, calcining the activated product to obtain the silicon powder.

6. The preparation method according to claim 5, characterized in that: In step S1, the treatment reagent is selected from at least one of ammonia water, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, hydrofluoric acid, sodium fluoride, ammonium fluoride, silicon tetrafluoride, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide and 1-butyl-3-methylimidazolium hexafluorophosphate; And / or, in step S1, the solvent I is selected from at least one of water, alcohols and ionic liquids; preferably at least one of deionized water, methanol, ethanol, n-butanol, isopropanol, ethylene glycol and 1-butyl-3-methylimidazolium hexafluorophosphate; And / or, in step S2, the silicon-containing raw material is selected from at least one of diatomaceous earth, water glass, silica sol, white carbon black, fumed silica sol, silicon powder, silicone resin microspheres, silicate, silicon tetrachloride and silane; wherein the silane is preferably selected from at least one of tetramethylsilane, methyltrimethoxysilane, isobutylenetriethoxysilane, trichlorosilane and tetraethoxysilane.

7. The preparation method according to claim 5 or 6, characterized in that: The molar ratio of the treatment reagent to SiO2 in the silicon-containing raw material is 0.0001 to 10:1; and / or, the molar ratio of the solvent I to SiO2 in the silicon-containing raw material is 0.5 to 50:1; And / or, the molar ratio of the total hydroxide anions in the treatment reagent and the solvent I to the SiO2 in the silicon-containing raw material is 2 to 60:

1.

8. The preparation method according to any one of claims 5 to 7, characterized in that: In step S2, the conditions for the mixing treatment include: a stirring speed of 0 to 5000 rpm, preferably 0 to 50 rpm; a temperature of 0 to 50° C., preferably 5 to 30° C.; And / or, in step S3, the conditions for performing the activation treatment include: a temperature of 0 to 200°C, preferably 0 to 100°C. And / or, in step S4, the calcination conditions include: a temperature of 150-1000°C, preferably 400-600°C; further preferably, within the range of 150-1000°C, at least two calcination temperatures are selected from low to high in an air atmosphere and calcined for 0.05-2 hours respectively.

9. An application of the silicon powder according to any one of claims 1 to 4 and / or the silicon powder prepared by the preparation method according to any one of claims 5 to 8 in the preparation of a silicon-containing crystalline material, wherein the silicon-containing crystalline material is preferably a titanium silicon molecular sieve, a silicon aluminum molecular sieve, a germanium silicon molecular sieve or a pure silicon porous material; the silicon-containing crystalline material is further preferably at least one of a TS-1 molecular sieve, a β molecular sieve, a ZSM-5 molecular sieve, an EU-1 molecular sieve, an MCM-22 molecular sieve, a SCM-4 molecular sieve, a Solicalite-2 molecular sieve, a mordenite molecular sieve, a symbiotic zeolite molecular sieve, and an SBA-15 molecular sieve.

10. The use according to claim 9, characterized in that: The nucleation induction period of the silicon-containing crystalline material at a temperature below 100° C. is less than 24 hours.

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