CN111253226B - Method for preparing lactic acid by catalyzing dihydroxyacetone and/or glyceraldehyde - Google Patents

Method for preparing lactic acid by catalyzing dihydroxyacetone and/or glyceraldehyde Download PDF

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CN111253226B
CN111253226B CN201811456790.9A CN201811456790A CN111253226B CN 111253226 B CN111253226 B CN 111253226B CN 201811456790 A CN201811456790 A CN 201811456790A CN 111253226 B CN111253226 B CN 111253226B
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molecular sieve
tin
titanium
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silicon
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CN111253226A (en
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朱斌
刘聿嘉
夏长久
赵毅
彭欣欣
杨永佳
林民
罗一斌
舒兴田
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Sinopec Research Institute of Petroleum Processing
China Petroleum and Chemical Corp
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China Petroleum and Chemical Corp
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    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
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    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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    • B01J29/89—Silicates, aluminosilicates or borosilicates of titanium, zirconium or hafnium
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    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/0009—Use of binding agents; Moulding; Pressing; Powdering; Granulating; Addition of materials ameliorating the mechanical properties of the product catalyst
    • B01J37/0018—Addition of a binding agent or of material, later completely removed among others as result of heat treatment, leaching or washing,(e.g. forming of pores; protective layer, desintegrating by heat)
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
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    • C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
    • C07C45/51—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by pyrolysis, rearrangement or decomposition
    • C07C45/511—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by pyrolysis, rearrangement or decomposition involving transformation of singly bound oxygen functional groups to >C = O groups
    • C07C45/512—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by pyrolysis, rearrangement or decomposition involving transformation of singly bound oxygen functional groups to >C = O groups the singly bound functional group being a free hydroxyl group
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
    • C07C45/51—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by pyrolysis, rearrangement or decomposition
    • C07C45/52—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by pyrolysis, rearrangement or decomposition by dehydration and rearrangement involving two hydroxy groups in the same molecule
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
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    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2229/00—Aspects of molecular sieve catalysts not covered by B01J29/00
    • B01J2229/10—After treatment, characterised by the effect to be obtained
    • B01J2229/18—After treatment, characterised by the effect to be obtained to introduce other elements into or onto the molecular sieve itself
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Abstract

The invention relates to a method for preparing lactic acid by catalyzing dihydroxyacetone and/or glyceraldehyde, which comprises the following steps: contacting reaction raw materials, water and a catalyst in a reactor and carrying out reaction to obtain a product containing lactic acid; wherein: the reaction raw materials contain dihydroxyacetone and/or glyceraldehyde, and the molar ratio of dihydroxyacetone and/or glyceraldehyde: water =1: (50-450), the reaction temperature is 30-180 ℃, the reaction time is 1-10h, the catalyst contains a tin-titanium-silicon molecular sieve, and the weight ratio of the weight of dihydroxyacetone and/or glyceraldehyde to the weight of the tin-titanium-silicon molecular sieve on a dry basis is 1: (1-6). The process of the present invention has high dihydroxyacetone/glyceraldehyde conversion and lactic acid yield.

Description

Method for preparing lactic acid by catalyzing dihydroxyacetone and/or glyceraldehyde
Technical Field
The invention relates to a method for preparing lactic acid by catalyzing dihydroxyacetone and/or glyceraldehyde.
Background
Lactic acid (2-hydroxypropionic acid, scientific name) is a compound that functions in a variety of biochemical processes, and has the molecular formula C 3 H 6 O 3 . It is a carboxylic acid containing a hydroxyl group and is therefore an alpha-hydroxy acid. Its carboxyl group in aqueous solution releases a proton, producing lactate ions. Lactate dehydrogenase converts pyruvate to L-lactate during fermentation. Lactic acid is produced continuously during normal metabolism and exercise, but its concentration does not generally rise. Lactic acid is a colorless liquid, and the industrial product is a colorless to pale yellow liquid. The natural plant extract is odorless, has hygroscopicity, has a relative density of 1.200, a melting point of 18 ℃, a boiling point of 122 ℃ and a flash point of more than 110 ℃, is miscible with ethanol, ether, water and glycerin, is insoluble in chloroform, carbon disulfide and petroleum ether, and is widely applied to the food industry, the pharmaceutical industry, the cosmetic industry and the agricultural and livestock industry.
The traditional lactic acid production method mainly adopts a sugar fermentation method and a chemical synthesis method. The fermentation method uses saccharides as raw materials, and the pH value of a fermentation system needs to be maintained within the range of 5.5-6.5, but the pH value is gradually reduced along with the continuous generation of lactic acid, so that calcium oxide or calcium carbonate needs to be continuously added in the reaction process to balance the pH value of the system. The calcium lactate produced is treated with sulphuric acid to give crude lactic acid, while a large amount of waste salt (calcium sulphate) is produced. However, crude lactic acid is difficult to separate, and it is necessary to react with alcohol to produce lactate having a relatively low boiling point, and then to obtain high-purity lactic acid through distillation separation and hydrolysis reaction. The process has long reaction route, high production cost and large amount of solid waste residue, so that large-scale production and application of the lactic acid cannot be realized at present. The commonly used chemical synthesis method is a lactonitrile method and a propionic acid method, the lactonitrile method uses acetaldehyde and hypertoxic hydrocyanic acid as reaction raw materials, and concentrated sulfuric acid is a catalyst, so that the pollution in the production process is serious, and potential safety hazards exist. The propionic acid method uses toxic chlorine as a raw material, has high requirements on operation safety and tightness, and is easy to cause pollution to the atmospheric environment.
Disclosure of Invention
The invention aims to provide a method for preparing lactic acid by catalyzing dihydroxyacetone and/or glyceraldehyde, which has high conversion rate of dihydroxyacetone/glyceraldehyde and high yield of lactic acid.
In order to accomplish the above objects, the present invention provides a method for preparing lactic acid by catalyzing dihydroxyacetone and/or glyceraldehyde, the method comprising:
contacting reaction raw materials, water and a catalyst in a reactor and reacting to obtain a product containing lactic acid; wherein:
the reaction raw materials contain dihydroxyacetone and/or glyceraldehyde, and the molar ratio of dihydroxyacetone and/or glyceraldehyde: water =1: (50-450), the reaction temperature is 30-180 ℃, the reaction time is 1-10h, the catalyst contains a tin-titanium-silicon molecular sieve, and the weight ratio of the weight of dihydroxyacetone and/or glyceraldehyde to the weight of the tin-titanium-silicon molecular sieve on a dry basis is 1: (1-6).
Optionally, the tin-titanium-silicon molecular sieve is selected from one or more of an MFI type tin-titanium-silicon molecular sieve, an MEL type tin-titanium-silicon molecular sieve, a BEA type tin-titanium-silicon molecular sieve, an MWW type tin-titanium-silicon molecular sieve, an MOR type tin-titanium-silicon molecular sieve, a hexagonal structure tin-titanium-silicon molecular sieve and an FAU type tin-titanium-silicon molecular sieve.
Optionally, the tin-titanium-silicon molecular sieve is selected from one or more of Sn-Ti-MFI molecular sieve, sn-Ti-MEL molecular sieve, sn-Ti-Beta molecular sieve, sn-Ti-MCM-22 molecular sieve, sn-Ti-MOR molecular sieve, sn-Ti-MCM-41 molecular sieve, sn-Ti-SBA-15 molecular sieve and Sn-Ti-USY molecular sieve.
Optionally, the tin-titanium-silicon molecular sieve contains a silicon element, a titanium element, a tin element and an oxygen element;
preferably, at least part of the inner part of crystal grains of the tin-titanium-silicon molecular sieve has a cavity structure;
preferably, the proportion of the external specific surface area of the tin-titanium-silicon molecular sieve in the total specific surface area is more than 10%, and the total specific surface area is 300m 2 More than g, and the external specific surface area is 20m 2 More than g;
preferably, the tin-titanium-silicon molecular sieve has a diffraction peak at 0.5-9 degrees in 2 theta in an XRD pattern;
preferably, the tin-titanium-silicon molecular sieve is 460cm in FT-IR spectrum -1 、975cm -1 、800cm -1 And 1080cm -1 There is absorption nearby;
preferably, the tin-titanium-silicon molecular sieve has absorption at 200-300nm in a UV-Vis spectrum;
preferably, the proportion of the external specific surface area of the tin-titanium-silicon molecular sieve in the total specific surface area is 10-25%, and the total specific surface area is 310-600m 2 Per g, external specific surface area of 31-150m 2 /g；
Preferably, the tin-titanium-silicon molecular sieve is P/P at 25 DEG C 0 An amount of benzene adsorbed of at least 35mg/g as measured with an adsorption time of 1 hour and 0.10; at a relative pressure P/P 0 If the molar ratio is about 0.60, the difference between the nitrogen adsorption amount during desorption and the nitrogen adsorption amount during adsorption of the tin-titanium-silicon molecular sieve is greater than 2% of the nitrogen adsorption amount during adsorption of the tin-titanium-silicon molecular sieve;
preferably, a hysteresis loop exists between the adsorption isotherm and the desorption isotherm of the low-temperature nitrogen adsorption of the tin-titanium-silicon molecular sieve;
preferably, the radial length of the cavity part of the cavity structure inside the crystal grains of the tin-titanium-silicon molecular sieve is 0.5-300nm;
preferably, the molar ratio of the tin element to the silicon element in the tin-titanium-silicon molecular sieve is 0.05-10.
Optionally, the preparation method of the tin-titanium-silicon molecular sieve comprises the following steps:
(1) Contacting a tin source, a titanium source and a template agent in the presence of an aqueous solvent to obtain a first mixture;
(2) Mixing the first mixture with a silicon molecular sieve to obtain a second mixture;
(3) And crystallizing the second mixture under the hydrothermal crystallization condition.
Optionally, in step (1), the contacting conditions include: the contact temperature is 20-80 ℃, and the contact time is 1-240min;
preferably, the silicon molecular sieve and the tin source are used in such an amount that the molar ratio of tin element to silicon element in the prepared tin-titanium-silicon molecular sieve is 0.05-10; the dosage of the silicon molecular sieve and the titanium source ensures that the molar ratio of the titanium element to the silicon element in the prepared tin-titanium-silicon molecular sieve is 0.05-10;
preferably, the molar ratio of the silicon molecular sieve, the template agent, the titanium source, the tin source and the water is from 0.005 to 20 2 The tin source is calculated by tin element, and the titanium source is calculated by TiO 2 Counting;
preferably, the hydrothermal crystallization conditions include: the crystallization temperature is 80-200 ℃ under the closed condition, and the crystallization time is 6-150h;
preferably, the tin source is an inorganic tin compound and/or an organotin compound; the titanium source is an inorganic titanium compound and/or an organic titanium compound; the template agent is one or more of aliphatic amine compound, aliphatic alcohol amine compound and quaternary ammonium base compound; the silicon molecular sieve is one or more selected from S-1, S-2, BETA, MOR, MCM-22, MCM-41, SBA-15 and MCM-48;
preferably, at least part of the inner part of crystal grains of the tin-titanium-silicon molecular sieve has a cavity structure, and a diffraction peak is arranged at 0.5-9 degrees in 2 theta in an XRD pattern; 460cm in the FT-IR spectrum -1 、975cm -1 、800cm -1 、1080cm -1 Nearby absorption; in thatThe absorption is carried out at 200-300nm in a UV-Vis spectrum, and the total specific surface area of the tin-titanium-silicon molecular sieve is 300m 2 More than g, and the external specific surface area is 30m 2 More than g, and the proportion of the external specific surface area to the total specific surface area is more than 10 percent.
Optionally, the tin-titanium-silicon molecular sieve is obtained by carrying out secondary hydrothermal synthesis on a titanium-silicon molecular sieve and a compound containing a tin source, a template, alkali and water at 100-160 ℃, and then carrying out filtering separation, drying and roasting operations, wherein the content of tin in the molecular sieve is 1-5 wt% calculated by oxides;
preferably, the tin-titanium-silicon molecular sieve is one or a mixture of more of Sn-TS-1, sn-TS-2, sn-Ti-BETA, sn-Ti-MCM-22, sn-Ti-MCM-41 and Sn-Ti-MCM-48.
Optionally, the Sn-TS-1 is a titanium silicalite molecular sieve having an MFI crystal structure, crystal grains are hollow, and the radial length of a cavity portion of the hollow crystal grains is 5 to 300 nanometers; the molecular sieve sample is at 25 ℃ and P/P 0 =0.10, the benzene adsorption amount measured under the condition of adsorption time of 1 hour is at least 70 mg/g, and a hysteresis loop exists between the adsorption isotherm and the desorption isotherm of low-temperature nitrogen adsorption of the molecular sieve.
Optionally, dihydroxyacetone and/or glyceraldehyde: water =1: (60-200), the weight ratio of the dihydroxyacetone and/or glyceraldehyde to the weight of the tin-titanium-silicon molecular sieve on a dry basis is 1: (1.2-3), the reaction temperature is 40-120 ℃, the reaction time is 2-8h, the reaction pressure is 0.1-3MPa, and the reaction pressure is preferably 0.1-2MPa.
Optionally, the reactor is a tank reactor, a fixed bed reactor, a moving bed, a suspended bed or a slurry bed reactor.
The method adopts the catalyst containing the binary tin-titanium-silicon molecular sieve, the framework tin atoms of the molecular sieve activate the carbonyl in the dihydroxyacetone and/or the glyceraldehyde to generate the methylglyoxal, and the framework tin atoms and the framework titanium atoms of the molecular sieve synergistically catalyze the methylglyoxal to generate the lactic acid, so that the reaction efficiency is improved. Compared with the prior art, the method can obtain higher dihydroxyacetone/glyceraldehyde conversion rate and lactic acid yield under mild reaction conditions in a short time, has lower energy consumption for subsequent separation of products, is safer and more efficient in process, and is suitable for large-scale industrial production and application.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:
FIG. 1 is a diagram showing the reaction mechanism involved in the conversion of dihydroxyacetone and glyceraldehyde into lactic acid according to the present invention.
Detailed Description
The following describes in detail specific embodiments of the present invention. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.
In the present invention, the dry weight means the weight measured after the sample is baked at 550 ℃ for 3 hours.
The invention provides a method for preparing lactic acid by catalyzing dihydroxyacetone and/or glyceraldehyde, which comprises the following steps: contacting reaction raw materials, water and a catalyst in a reactor and reacting to obtain a product containing lactic acid; wherein: the reaction raw materials contain dihydroxyacetone and/or glyceraldehyde, and the molar ratio of dihydroxyacetone and/or glyceraldehyde: water =1: (50-450), the reaction temperature is 30-180 ℃, the reaction time is 1-10h, the catalyst contains a tin-titanium-silicon molecular sieve, and the weight ratio of the weight of dihydroxyacetone and/or glyceraldehyde to the weight of the tin-titanium-silicon molecular sieve on a dry basis is 1: (1-6). The reaction mechanism is shown in figure 1.
It will be appreciated by those skilled in the art that, as shown in FIG. 1, the method of the present invention actually includes the following three cases:
1. dihydroxyacetone is reacted with water, whereupon the molar ratio of dihydroxyacetone and/or glyceraldehyde: the water is dihydroxyacetone: water, dihydroxyacetone/glyceraldehyde conversion means dihydroxyacetone conversion, the weight of dihydroxyacetone and/or glyceraldehyde being the weight of dihydroxyacetone;
2. glyceraldehyde reacts with water when dihydroxyacetone and/or glyceraldehyde: water is glyceraldehyde: water, dihydroxyacetone/glyceraldehyde conversion rate means glyceraldehyde conversion rate, and the weight of dihydroxyacetone and/or glyceraldehyde is the weight of glyceraldehyde;
3. dihydroxyacetone and glyceraldehyde are simultaneously reacted with water, in which case the molar ratio of dihydroxyacetone and/or glyceraldehyde: water is dihydroxyacetone and glyceraldehyde: water, dihydroxyacetone/glyceraldehyde conversion refers to the molar weighted conversion (i.e., weight is molar ratio) of dihydroxyacetone and glyceraldehyde, the weight of dihydroxyacetone and/or glyceraldehyde being the total weight of dihydroxyacetone and glyceraldehyde, which may be reacted together with water in any mixing ratio.
According to the present invention, the tin-titanium-silicon molecular sieve refers to a molecular sieve obtained by substituting a part of silicon atoms in a lattice framework of the molecular sieve with tin atoms and titanium atoms, wherein the content of the tin atoms and the titanium atoms in the molecular sieve can be determined by a conventional XRF method in the art, and the content of the tin atoms and the titanium atoms in the framework of the molecular sieve can be determined by using an ultraviolet spectrum or an infrared spectrum, for example, when a tin-titanium-silicon molecular sieve sample is analyzed by using the ultraviolet spectrum, a characteristic absorption peak of the framework tin atoms appears near 190nm, and a characteristic absorption peak of the framework Ti atoms appears near 210 nm. Pyridine infrared spectrum at 1450cm -1 The peaks around the molecular sieve show the L-acidic character of the molecular sieve and are provided by framework tin atoms and framework titanium atoms.
According to the present invention, the tin-titanium-silicon molecular sieve may be a product of replacing a part of framework silicon of various topological structure molecular sieves with tin atoms and titanium atoms, the topological structure of the molecular sieve may be referred to the website of International Zeolite Association (IZA), for example, the tin-titanium-silicon molecular sieve may be selected from one or more of MFI-type tin-titanium-silicon molecular sieve, such as Sn-Ti-MFI molecular sieve, MEL-type tin-titanium-silicon molecular sieve, BEA-type tin-titanium-silicon molecular sieve, MWW-type tin-titanium-silicon molecular sieve, such as Sn-Ti-MFI molecular sieve, MOR-type tin-titanium-silicon molecular sieve, such as Sn-Ti-MEL molecular sieve, BEA-type tin-titanium-silicon molecular sieve, such as Sn-Ti-Beta molecular sieve, MWW-type tin-titanium-silicon molecular sieve, such as Sn-Ti-MCM-22 molecular sieve, MOR-type tin-titanium-silicon molecular sieve, such as Sn-Ti-Beta molecular sieve, hexagonal structure, such as FAU-type tin-titanium-molecular sieve, such as Sn-Ti-ussi molecular sieve, such as FAU-molecular sieve, favi-Ti-molecular sieve, favi-type tin-titanium-molecular sieve; preferably, the tin-titanium-silicon molecular sieve is one or more of an MFI type tin-titanium-silicon molecular sieve, a BEA type tin-titanium-silicon molecular sieve and an FAU type tin-titanium-silicon molecular sieve, more preferably an MFI type tin-titanium-silicon molecular sieve, which can be obtained by commercial purchase or prepared by the methods disclosed in chinese patents CN105217645a and CN102452918a, and the following two specific embodiments of the tin-titanium-silicon molecular sieve are provided.
An embodiment of the first tin titanium silicalite molecular sieve is from patent CN105217645a.
According to a first embodiment, the tin-titanium-silicon molecular sieve contains silicon, titanium, tin and oxygen, wherein at least part of the crystal grains of the tin-titanium-silicon molecular sieve have a cavity structure inside. The fact that at least part of the tin titanium silicalite molecular sieves have a cavity structure inside the crystal grains means that at least part of the tin titanium silicalite molecular sieves in a large number of the tin titanium silicalite molecular sieves have a cavity structure inside the crystal grains, preferably more than 50% of the tin titanium silicalite molecular sieves have a cavity structure inside the crystal grains, and more preferably 70-100% of the tin titanium silicalite molecular sieves have a cavity structure inside the crystal grains.
According to the first embodiment, the ratio of the external specific surface area of the tin-titanium-silicon molecular sieve to the total specific surface area is preferably 10% or more, preferably 10 to 25%, more preferably 10 to 20%, and still more preferably 12 to 18%. The total specific surface area is preferably 300m 2 More preferably 310 to 600 m/g 2 G, more preferably from 350 to 460m 2 (ii) in terms of/g. The external specific surface area is 20m 2 A ratio of at least 30 m/g, preferably 2 A ratio of one to more than g, more preferably 31 to 150m 2 Per g, more preferably 35 to 120m 2 Per g, most preferably 40 to 70m 2 /g。
According to a first embodiment, the total specific surface area refers to the BET specific surface area; and the external specific surface area refers to the surface area of the external surface of the tin-titanium-silicon molecular sieve, and can also be referred to as the external surface area for short. The total specific surface area, the external specific surface area and the like can be measured according to the standard method of ASTM D4222-98.
According to a first embodiment, the crystalline tin-titanium-silicon molecular sieve with a cavity structure has the spectral properties of a conventional tin-titanium-silicon molecular sieve, and specifically, the tin-titanium-silicon molecular sieve has a diffraction peak at 0.5 to 9 degrees in 2 theta, preferably a diffraction peak at 5 to 9 degrees in 2 theta in an XRD pattern.
According to a first embodiment, the tin-titanium-silicon molecular sieve is preferably 460cm in the FT-IR spectrum -1 、975cm -1 、800cm -1 And 1080cm -1 There is absorption in the vicinity. Preferably, the tin-titanium-silicon molecular sieve has absorption at 200-300nm in a UV-Vis spectrum, and preferably has absorption at 200-260 nm.
According to the first embodiment, the molar ratio of the tin element to the silicon element in the tin-titanium-silicon molecular sieve is preferably from 0.05 to 10, more preferably from 0.1 to 5, and particularly preferably from 0.2 to 2. Preferably, the molar ratio of the titanium element to the silicon element in the tin-titanium-silicon molecular sieve is 0.05-10, more preferably 0.1-5. The tin element, the titanium element and the silicon element in the proportion can further optimize the catalytic activity of the tin-titanium-silicon molecular sieve.
According to a first embodiment, the tin-titanium-silicon molecular sieve is preferably P/P at 25 ℃ 0 An amount of benzene adsorbed of at least 25mg/g, preferably at least 35mg/g, preferably from 40 to 100mg/g, as measured at 0.10 and an adsorption time of 1 hour.
According to a first embodiment, the tin-titanium-silicon molecular sieve is preferably at a relative pressure P/P 0 When the molar ratio is about 0.60, the difference between the nitrogen adsorption amount during desorption and the nitrogen adsorption amount during adsorption of the tin-titanium-silicon molecular sieve is greater than 2% of the nitrogen adsorption amount during adsorption of the tin-titanium-silicon molecular sieve, preferably, the difference between the nitrogen adsorption amount during desorption and the nitrogen adsorption amount during adsorption of the tin-titanium-silicon molecular sieve is greater than 5% of the nitrogen adsorption amount during adsorption of the tin-titanium-silicon molecular sieve, and more preferably, the difference between the nitrogen adsorption amount during desorption and the nitrogen adsorption amount during adsorption of the tin-titanium-silicon molecular sieve is greater than 5% of the nitrogen adsorption amount during adsorption of the tin-titanium-silicon molecular sieve6-10% of the nitrogen adsorption amount.
According to the first embodiment, a hysteresis loop is preferably present between the adsorption isotherm and the desorption isotherm of the low temperature nitrogen adsorption of the tin titanium silicalite molecular sieve. Preferably, the radial length of the cavity part of the cavity structure in the crystal grain of the tin-titanium-silicon molecular sieve is 0.1-500nm, and the preferred length is 0.5-300nm.
According to a first embodiment, the method of making a tin-titanium-silicon molecular sieve comprises:
(1) Contacting a tin source, a titanium source and a template agent in the presence of an aqueous solvent to obtain a first mixture;
(2) Mixing the first mixture with a silicon molecular sieve to obtain a second mixture;
(3) And crystallizing the second mixture under the hydrothermal crystallization condition.
According to the first embodiment, the temperature of the contact is wide in a selectable range, and for the preferred step (1) of the invention, the contact conditions include: the contact temperature is 20 to 80 deg.C, more preferably 25 to 60 deg.C, and still more preferably 25 to 40 deg.C. Thus, the activity of the tin-titanium-silicon molecular sieve can be improved. The contacting time can be determined according to specific needs, and preferably in step (1), the contacting conditions further include: the contact time is 1-240min, more preferably 5-120min, and still more preferably 20-60min.
According to the first embodiment, the amount of the silicon molecular sieve and the tin source is preferably such that the molar ratio of the tin element to the silicon element in the prepared tin-titanium-silicon molecular sieve is from 0.05 to 100, preferably from 0.1 to 5, and more preferably from 0.5 to 2; the dosage of the silicon molecular sieve and the titanium source is such that the molar ratio of the titanium element to the silicon element in the prepared tin-titanium-silicon molecular sieve is 0.05-10, preferably 0.1-5, more preferably 0.5-4.
According to a first embodiment, to achieve the above object, the molar ratio of the silicalite, the templating agent, the titanium source, the tin source and the water is preferably from 100-2, wherein the silicon molecular sieve is SiO 2 The tin source is calculated by tin element, and the titanium source is calculated by TiO 2 And (6) counting.
According to the first embodiment, it is preferable that the conditions for mixing in the step (2) include: the mixing temperature is 25-60 deg.C, and the mixing time is 20-60min. Preferably, the hydrothermal crystallization conditions include: the crystallization temperature under a closed condition is 80 to 200 ℃, more preferably 100 to 180 ℃, still more preferably 110 to 175 ℃, and most preferably 160 to 170 ℃. The crystallization time is preferably 6 to 150 hours, more preferably 24 to 96 hours.
According to the first embodiment, the variety of the tin source can be widely selected, and any substance containing tin (for example, a compound containing tin element and/or a simple substance of tin) can achieve the object of the present invention. The inorganic tin compound is, for example, a water-soluble inorganic tin salt, which may be, for example, one or more of tin chloride, tin chloride pentahydrate, stannous chloride, tin nitrate, tin sulfate, tin phosphate, stannous chloride hydrate, metastannic acid, calcium stannate, potassium stannate, sodium stannate, lithium stannate, magnesium stannate, stannous sulfate, stannous pyrophosphate, and tin pyrophosphate; the organic acid salt of tin is preferably a C2-C10 organic acid salt, including but not limited to one or more of tin acetate, stannous acetate and stannous octoate. The organotin compound may be an organic acid salt of tin and/or an organic ligand compound of tin, preferably a stannic acid ester. Among them, the most preferable organotin compound is tin acetate.
According to a first embodiment, the titanium source may be a conventional choice in the art, and may be an inorganic titanium compound and/or an organic titanium compound, preferably for the purposes of the present invention, the titanium source is selected from inorganic titanium salts and/or organic titanates, preferably organic titanates.
According to a first embodiment, the inorganic titanium salt is chosen from various hydrolysable titanium salts, such as may be chosen from TiX 4 、TiOX 2 Or Ti (SO) 4 ) 2 And various forms of titanium-containing salts, wherein X is halogen, preferablyIs selected from chlorine, wherein, the inorganic titanium salt is preferably selected from titanium trichloride and TiCl 4 、Ti(SO 4 ) 2 And TiOCl 2 One or more of (a).
According to a first embodiment, the organic titanate is preferably of formula M 4 TiO 4 Wherein M is preferably an alkyl group having 1 to 4 carbon atoms, and 4M's may be the same or different, preferably the organotitanate is selected from one or more of isopropyl titanate, n-propyl titanate, tetrabutyl titanate and tetraethyl titanate being used as examples in the specific embodiments of the present invention, but not thereby limiting the scope of the present invention.
According to the first embodiment, preferably the titanium source is one or more of tetrabutyl titanate, titanium tetrachloride, tetraisopropyl titanate and titanium trichloride.
According to the first embodiment, the selection range of the template agent is wide, and the template agent can be specifically selected according to the type of the tin-titanium-silicon molecular sieve to be prepared, and those skilled in the art can know the type. For the present invention, it is preferable that the templating agent is one or more of an aliphatic amine compound, an aliphatic alcohol amine compound, and a quaternary ammonium base compound.
According to a first embodiment, the quaternary ammonium base can be any of various organic quaternary ammonium bases, and in particular, the quaternary ammonium base can be a quaternary ammonium base represented by the following formula:
Figure BDA0001887896380000081
in the above formula, R 5 、R 6 、R 7 And R 8 Each C1-C4 alkyl, including C1-C4 straight chain alkyls and C3-C4 branched chain alkyls, such as: r 5 、R 6 、R 7 And R 8 Each may be methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl or tert-butyl. More preferably, the quaternary ammonium base is one or more of tetrapropylammonium hydroxide, tetraethylammonium hydroxide and tetrabutylammonium hydroxide.
According to a first embodiment of the method of the invention,the aliphatic amine may be various NH 3 Is substituted with an aliphatic hydrocarbon group (preferably an alkyl group), and specifically, the aliphatic amine may be an aliphatic amine represented by the following formula: r 9 (NH 2 ) n (ii) a In the above formula, n is an integer of 1 or 2. When n is 1, R 9 Is C1-C6 alkyl, including C1-C6 straight chain alkyl and C3-C6 branched chain alkyl, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, neopentyl, isoamyl, tert-pentyl and n-hexyl. When n is 2, R 9 Is C1-C6 alkylene, including C1-C6 linear alkylene and C3-C6 branched alkylene, such as methylene, ethylene, n-propylene, n-butylene, n-pentylene, or n-hexylene. More preferably, the aliphatic amine compound is one or more of ethylamine, n-butylamine, butanediamine and hexamethylenediamine.
According to a first embodiment, the aliphatic alcohol amine can be any of various NH 3 In the above formula (b), at least one hydrogen of the aliphatic alcohol amine is substituted by a hydroxyl group-containing aliphatic hydrocarbon group (preferably an alkyl group), and specifically, the aliphatic alcohol amine may be represented by the following formula: (HOR) 10 ) m NH (3-m) (ii) a In the above formula, m are R 10 Identical or different, are each C1-C4 alkylene, including C1-C4 linear alkylene and C3-C4 branched alkylene, such as methylene, ethylene, n-propylene and n-butylene; m is 1, 2 or 3. More preferably, the aliphatic alcohol amine compound is one or more of monoethanolamine, diethanolamine and triethanolamine.
According to a first embodiment, the templating agent is preferably tetrapropylammonium hydroxide and/or tetraethylammonium hydroxide.
According to a first embodiment, the silicalite may be at least one of an MFI structure (e.g., S-1), an MEL structure (e.g., S-2), a BEA structure (e.g., beta), an MWW structure (e.g., MCM-22), a two-dimensional hexagonal structure (e.g., MCM-41, SBA-15), an MOR structure (e.g., MOR), a TUN structure (e.g., TUN), and other structures of silicalite (e.g., ZSM-48, MCM-48). Preferably, the silicon molecular sieve is one or more of a silicon molecular sieve with an MFI structure, a silicon molecular sieve with an MEL structure and a silicon molecular sieve with a BEA structure, more preferably a silicon molecular sieve with an MFI structure, and preferably, the silicon molecular sieve is one or more of S-1, S-2 and Beta, preferably S-1.
According to the first embodiment, the silicon molecular sieve can be obtained commercially or prepared, and the method for preparing the silicon molecular sieve is well known to those skilled in the art and is not described herein again.
According to the first embodiment, it is preferred that the method further comprises: and filtering and washing the crystallized product to obtain a solid, and roasting the obtained solid after drying or not drying. The methods of filtering the product obtained by crystallization, drying the solid obtained by filtering, and calcining are well known to those skilled in the art, and in the present invention, the optional range of the drying conditions is wide, and can be specifically performed with reference to the prior art. For the present invention, it is preferable that the drying conditions include: the temperature is between room temperature and 200 ℃, and is more preferably between 80 and 120 ℃; the time is 1-24h, preferably 2-10h.
According to a first embodiment, the conditions of the calcination can be chosen within a wide range, and for the purposes of the present invention, it is preferred that the conditions of the calcination include: the roasting temperature is 300-800 ℃, preferably 450-550 ℃; the roasting time is 2-12h, preferably 2-4h; more preferably, the firing conditions include: firstly, roasting for 0.5-6h at 350-600 ℃ in a nitrogen atmosphere, and then roasting for 0.5-12h at 350-600 ℃ in an air atmosphere. Methods of filtration and washing are also well known to those skilled in the art and will not be described in detail herein.
An embodiment of the second tin titanium silicalite molecular sieve is from patent CN102452918a.
According to a second embodiment, the tin-titanium-silicon molecular sieve is obtained by carrying out a second hydrothermal synthesis on a titanium-silicon molecular sieve together with a compound containing a tin source, a template, an alkali and water at 100-160 ℃, and then carrying out filtering separation, drying and roasting operations, wherein the tin content in the molecular sieve is 1-5 wt% calculated on oxide, and strong Lewis acid centers are formed at the skeleton position, thereby enhancing the activation of the molecular sieve on a substrate in an organic reaction.
According to a second embodiment, the tin-titanium-silicon molecular sieve is a mixture of one or more of Sn-TS-1, sn-TS-2, sn-Ti-BETA, sn-Ti-MCM-22, sn-Ti-MCM-41 and Sn-Ti-MCM-48. The preferable TS-1 is selected, and the synthesis method of the titanium silicalite TS-1 is firstly disclosed in the US patent USP 4410501. As a more preferable embodiment, the invention adopts a TS-1 titanium silicalite molecular sieve with a hollow structure, the molecular sieve has a titanium silicalite molecular sieve with an MFI crystal structure, crystal grains have a hollow structure, and the radial length of a cavity part of each hollow crystal grain is 5-300 nanometers; the molecular sieve sample has a benzene adsorption capacity of at least 70 mg/g measured at 25 ℃, P/P0=0.10, and an adsorption time of 1 hour, and a hysteresis loop exists between an adsorption isotherm and a desorption isotherm of low temperature nitrogen adsorption of the molecular sieve. The TS-1 titanium silicalite molecular sieve with a hollow structure has larger mesopore volume which is usually more than 0.16mL/g, while the conventional TS-1 titanium silicalite molecular sieve has the mesopore volume which is usually about 0.084 mL/g. The TS-1 titanium silicalite molecular sieve with the hollow structure can be purchased from commercial products, and can also be prepared by referring to the method disclosed in the Chinese patent ZL 99126289.1.
According to the invention, preferably, the molar ratio of dihydroxyacetone and/or glyceraldehyde: water =1: (60-200), the ratio of the weight of dihydroxyacetone and/or glyceraldehyde to the weight of the tin titanium silicalite molecular sieve on a dry basis is preferably 1: (1.2-3), the reaction temperature is preferably 40-120 ℃, the reaction time is preferably 2-8h, and the reaction pressure is preferably 0.1-2MPa.
The reaction according to the present invention may be carried out in a conventional catalytic reactor according to the present invention, and the present invention is not particularly limited, for example, the reaction according to the present invention may be carried out in a batch tank reactor or a three-neck flask, or in a suitable other reactor such as a fixed bed, a moving bed, a suspended bed, etc., preferably in a tank reactor, a fixed bed reactor, a moving bed, a suspended bed, or a slurry bed reactor, the specific operation of which is well known to those skilled in the art, and the detailed description of the present invention will be omitted.
According to the present invention, it can be understood by those skilled in the art that, depending on the reactor used, the tin-titanium-silicon molecular sieve of the present invention may be a molecular sieve raw powder, or a molded catalyst formed by mixing a molecular sieve and a carrier. The separation of the lactic acid-containing product from the catalyst can be achieved in various ways, for example, when the raw powdery molecular sieve is used as the catalyst, the separation of the product and the recovery and reuse of the catalyst can be achieved by settling, filtration, centrifugation, evaporation, membrane separation, or the like, or the catalyst can be molded and then packed in a fixed bed reactor, and the catalyst can be recovered after the reaction is completed.
The present invention is further illustrated by the following examples, which are not intended to limit the scope of the invention.
The starting materials used in the preparation examples, preparation comparative examples, examples and comparative examples were chemically pure reagents, unless otherwise specified.
In the invention, the X-ray diffraction (XRD) crystal phase diagram of a sample is determined on a Siemens D5005 type X-ray diffractometer, the radiation source is Ka (Cu), and the test range 2 theta is 0.5-30 degrees. The Fourier infrared (FT-IR) spectrum of the sample is measured on a Nicolet8210 type Fourier infrared spectrometer, and the measuring range is 400-4000cm -1 . The solid ultraviolet-visible diffuse reflectance spectrum (UV-vis) of the sample is measured on a SHIMADZU UV-3100 model ultraviolet-visible spectrometer, and the measuring range is 200-1000nm. The total specific surface area and the external specific surface area of the sample were measured on a Micromeritics ASAP2405 static nitrogen adsorption apparatus according to ASTM D4222-98 standard method. TEM transmission electron micrographs of the samples were obtained on a transmission electron microscope of the type Tecnai G2F20S-TWIN, from FEI.
In the present invention, the benzene adsorption amount is measured by a conventional static adsorption method, and the adsorption isotherm and the desorption isotherm of low-temperature nitrogen adsorption are measured according to the ASTM D4222-98 standard method.
In the present invention, the molecular sieve yield refers to the percentage of the mass of the product actually obtained to the theoretically calculated mass (based on the total amount of silica, titanium dioxide and tin dioxide charged).
In the invention, in a transmission electron microscope test, a certain number of crystal grains in a certain visual field range are taken as a representative crystal grain, such as 100 crystal grains, and the proportion of the number of the crystal grains with the cavity structures in the crystal grains in the total number of the crystal grains is observed, so that the proportion of the tin-titanium-silicon molecular sieves with the cavity structures in the crystal grains in the total number of the tin-titanium-silicon molecular sieves is calculated.
In the invention, the gas chromatography is adopted to analyze each component in the activity evaluation system, the analysis result is quantified by an internal standard method, and the internal standard substance is naphthalene. Wherein, the chromatographic analysis conditions are as follows: agilent-6890 type chromatograph, HP-5 capillary chromatographic column, sample amount of 0.5 μ L, and sample inlet temperature of 280 deg.C. The column temperature was maintained at 100 ℃ for 2min, then ramped up to 200 ℃ at a rate of 15 ℃/min and maintained for 3min. FID detector, detector temperature 300 ℃.
In the invention:
dihydroxyacetone/glyceraldehyde conversion% = (moles of dihydroxyacetone/glyceraldehyde in the starting material-moles of dihydroxyacetone/glyceraldehyde in the product) ÷ moles of dihydroxyacetone/glyceraldehyde in the starting material × 100%;
lactic acid selectivity% = mole of lactic acid in product ÷ (mole of dihydroxyacetone/glyceraldehyde in starting material-mole of dihydroxyacetone/glyceraldehyde in product) × 100%;
lactic acid yield% = mole of lactic acid in product ÷ mole of dihydroxyacetone/glyceraldehyde in raw material × 100%, i.e.,% lactic acid yield% = lactic acid selectivity% × dihydroxyacetone/glyceraldehyde conversion%.
Preparation examples and preparation comparative examples catalysts used in the examples and comparative examples were provided.
Preparation of example 1
The preparation example prepares the Sn-Ti-MFI-1 molecular sieve according to the method of the specification example 1 of the Chinese patent CN105217645A, and the specific preparation method is as follows:
(1) Stirring and contacting tetrapropylammonium hydroxide aqueous solution (with the concentration of 15 weight percent) with tetrabutyl titanate and stannic chloride pentahydrate for 30min at 25 ℃ to obtain a mixture;
(2) Adding the silicon molecular sieve S-1 into the mixture at 60 ℃, stirring and contacting for 0.5h to obtain a mixture (in the contact process, adding water or not adding water according to the needs)If the feeding in the step (1) can meet the feeding requirement of water, water is not needed to be added, and if the feeding cannot meet the feeding requirement of water, water can be additionally added when a mixture containing tetrapropylammonium hydroxide, tetrabutyl titanate and tin chloride is stirred and contacted with a silicon molecular sieve, or water is removed by distillation, and other preparation examples are similar and are not repeated); wherein, the feeding molar ratio of each substance is ensured as follows: silicon source (silicon molecular sieve), alkali source template agent (tetrapropylammonium hydroxide), titanium source (tetrabutyl titanate): tin source (crystalline tin tetrachloride): water =100 2 The titanium source is calculated as TiO 2 The tin source is calculated by the tin element;
(3) And transferring the mixture into a stainless steel sealed reaction kettle, crystallizing for 144 hours at the temperature of 170 ℃ under autogenous pressure, filtering the obtained crystallized product, washing with water, drying for 120 minutes at the temperature of 110 ℃, and roasting for 3 hours at the temperature of 550 ℃ to obtain the tin-titanium-silicon molecular sieve.
XRF composition analysis shows that the tin-titanium-silicon molecular sieve has tin content of 1.8 wt% and titanium content of 0.9 wt%; TEM indicates that 100% of the tin-titanium-silicon molecular sieve grains have a cavity structure; in an XRD crystal phase diagram, a diffraction peak exists at the 2 theta position of 5-9 degrees; in FT-IR, 460cm -1 、800cm -1 、975cm -1 、1080cm -1 Nearby absorption; in UV-Vis, there is an absorption at 220 nm; a hysteresis loop exists between an adsorption isotherm and a desorption isotherm of low-temperature nitrogen adsorption, the yield of the molecular sieve is 94 percent, the benzene adsorption capacity is 62mg/g, the ratio of an adsorption-desorption difference value to an adsorption capacity (the difference between the nitrogen adsorption capacity during desorption and the nitrogen adsorption capacity during adsorption of the tin-titanium-silicon molecular sieve is greater than the nitrogen adsorption capacity during adsorption of the tin-titanium-silicon molecular sieve) is 6 percent, and the total specific surface area is 440m 2 Per g, external specific surface area of 46m 2 The proportion of the external specific surface area to the total specific surface area was 10.5%.
Preparation of example 2
The preparation example prepares the Sn-Ti-MFI-2 molecular sieve according to the method of the specification example 2 of the Chinese patent CN105217645A, and the specific preparation method is as follows:
(1) Stirring and contacting tetrapropylammonium hydroxide aqueous solution (with the concentration of 20 weight percent) with tetrabutyl titanate and stannic chloride pentahydrate for 30min at 25 ℃ to obtain a mixture;
(2) Adding a silicon molecular sieve S-1 into the mixture at 25 ℃, and stirring and contacting for 0.5h to obtain a mixture; wherein, the feeding molar ratio of each substance is ensured as follows: silicon source (silicon molecular sieve), alkali source template agent (tetrapropylammonium hydroxide), titanium source (tetrabutyl titanate): tin source (tin tetrachloride): water =100 2 The titanium source is calculated as TiO 2 The tin source is calculated by the tin element;
(3) And transferring the mixture into a stainless steel sealed reaction kettle, crystallizing for 120 hours at the temperature of 160 ℃ and the autogenous pressure, filtering the obtained crystallized product, washing with water, drying for 120 minutes at the temperature of 110 ℃, and then roasting for 3 hours at the temperature of 550 ℃ to obtain the tin-titanium-silicon molecular sieve.
By XRF composition analysis, the Sn mass percentage content of the tin-titanium-silicon molecular sieve is 1.0, and the titanium mass percentage content is 2.6; in an XRD crystal phase diagram, diffraction peaks exist at 5-9 degrees of 2 theta; TEM indicates that the inside of 100% molecular sieve crystal grains is a cavity structure; in FT-IR, 460cm -1 、800cm -1 、975cm -1 、1080cm -1 Nearby absorption; in UV-Vis, there is an absorption at 220 nm; a hysteresis loop exists between the adsorption isotherm and the desorption isotherm of low-temperature nitrogen adsorption, the molecular sieve yield is 93 percent, the benzene adsorption capacity is 68mg/g, the ratio of the adsorption-desorption difference value to the adsorption capacity (the difference value between the nitrogen adsorption capacity during desorption and the nitrogen adsorption capacity during adsorption of the tin-titanium-silicon molecular sieve is greater than the nitrogen adsorption capacity during adsorption of the tin-titanium-silicon molecular sieve) is 8 percent, and the total specific surface area is 424m 2 A specific surface area of 45m 2 The proportion of the external specific surface area to the total specific surface area was 10.6%.
Preparation of example 3
The preparation example prepares the Sn-Ti-MFI-3 molecular sieve according to the method of the specification example 3 of the Chinese patent CN105217645A, and the specific preparation method is as follows:
(1) A mixture was obtained by contacting an aqueous tetraethylammonium hydroxide solution (concentration of 28% by weight) with titanium tetrachloride and tin nitrate at 35 ℃ for 30 minutes with stirring;
(2) In thatAdding a silicon molecular sieve S-1 into the mixture at 50 ℃, and stirring and contacting for 0.5h to obtain a mixture; wherein, the feeding molar ratio of each substance is ensured as follows: silicon source (silicon molecular sieve), alkali source templating agent (tetraethylammonium hydroxide), titanium source (titanium tetrachloride), tin source (tin nitrate), water =100 2 The titanium source is TiO 2 The tin source is calculated by the tin element;
(3) And transferring the mixture into a stainless steel sealed reaction kettle, crystallizing for 96 hours at the temperature of 170 ℃ and the autogenous pressure, filtering the obtained crystallized product, washing with water, drying for 120 minutes at the temperature of 110 ℃, and then roasting for 3 hours at the temperature of 550 ℃ to obtain the tin-titanium-silicon molecular sieve.
By XRF composition analysis, the Sn mass percent of the tin-titanium-silicon molecular sieve is 0.8, and the titanium mass percent is 0.3; in an XRD crystal phase diagram, diffraction peaks exist at 5-9 degrees of 2 theta; TEM indicates that the inside of 100% molecular sieve crystal grains is a cavity structure; in FT-IR, 460cm -1 、800cm -1 、975cm -1 、1080cm -1 There is absorption nearby; in UV-Vis, there is an absorption at 230 nm; a hysteresis loop exists between an adsorption isotherm and a desorption isotherm of low-temperature nitrogen adsorption, the molecular sieve yield is 94%, the benzene adsorption capacity is 54mg/g, the ratio of an adsorption-desorption difference value to an adsorption capacity (the difference between the nitrogen adsorption capacity during desorption and the nitrogen adsorption capacity during adsorption of the tin-titanium-silicon molecular sieve is greater than the nitrogen adsorption capacity during adsorption of the tin-titanium-silicon molecular sieve) is 5%, and the total specific surface area is 431m 2 Per g, external specific surface area 43m 2 The proportion of the external specific surface area to the total specific surface area is 10%.
Preparation of example 4
The preparation example prepares the Sn-Ti-MFI-4 molecular sieve according to the method of the specification example 4 of the Chinese patent CN105217645A, and the specific preparation method is as follows:
(1) Stirring and contacting tetrapropylammonium hydroxide aqueous solution (with the concentration of 15 weight percent) with tetraisopropyl titanate and stannic chloride for 30min at the temperature of 30 ℃ to obtain a mixture;
(2) Adding a silicon molecular sieve S-1 into the mixture at 60 ℃, and stirring and contacting for 0.5h to obtain a mixture; wherein, the feeding of each substance is ensuredThe molar ratio is as follows: silicon source (silicon molecular sieve), alkali source template (tetrapropylammonium hydroxide), titanium source (tetraisopropyl titanate), tin source (tin tetrachloride), water =100 2 The titanium source is TiO 2 The tin source is calculated by the tin element;
(3) And transferring the mixture into a stainless steel sealed reaction kettle, crystallizing for 72 hours at the temperature of 120 ℃ under autogenous pressure, filtering the obtained crystallized product, washing with water, drying for 120 minutes at the temperature of 110 ℃, and roasting for 3 hours at the temperature of 550 ℃ to obtain the tin-titanium-silicon molecular sieve.
By XRF composition analysis, the Sn mass percent of the tin-titanium-silicon molecular sieve is 6.6, and the titanium mass percent is 2.1; in an XRD crystal phase diagram, diffraction peaks exist at 5-9 degrees of 2 theta; TEM indicates that 96% of the molecular sieve crystal grains have a cavity structure; in FT-IR, 460cm -1 、800cm -1 、975cm -1 、1080cm -1 Nearby absorption; in UV-Vis, there is absorption around 240 nm; a hysteresis loop exists between the adsorption isotherm and the desorption isotherm of low-temperature nitrogen adsorption, the molecular sieve yield is 94 percent, the benzene adsorption capacity is 83mg/g, the ratio of the adsorption-desorption difference value to the adsorption capacity (the difference value between the nitrogen adsorption capacity during desorption and the nitrogen adsorption capacity during adsorption of the tin-titanium-silicon molecular sieve is greater than the nitrogen adsorption capacity during adsorption of the tin-titanium-silicon molecular sieve) is 9 percent, and the total specific surface area is 416m 2 Per g, external specific surface area of 50m 2 The proportion of the external specific surface area to the total specific surface area was 12.1%.
Preparation of example 5
The preparation example prepares the Sn-Ti-MFI-5 molecular sieve according to the method of the specification example 7 of the Chinese patent CN105217645A. The preparation method comprises the following steps:
(1) Stirring and contacting tetrapropylammonium hydroxide aqueous solution (with the concentration of 15 weight percent) with titanium trichloride and stannic chloride pentahydrate for 30min at the temperature of 25 ℃ to obtain a mixture;
(2) Adding a silicon molecular sieve S-1 into the mixture at 40 ℃, and stirring and contacting for 0.5h to obtain a mixture; wherein, the feeding molar ratio of each substance is ensured as follows: silicon source (silicon molecular sieve), alkali template agent (tetrapropylammonium hydroxide), titanium source (titanium trichloride), tin source (crystal tetrachloro)Tin oxide) water =100, wherein the silicon source is SiO 2 The titanium source is calculated as TiO 2 The tin source is calculated by the tin element;
(3) And transferring the mixture into a stainless steel sealed reaction kettle, crystallizing for 36 hours at the temperature of 170 ℃ and the autogenous pressure, filtering the obtained crystallized product, washing with water, drying for 120 minutes at the temperature of 110 ℃, and then roasting for 3 hours at the temperature of 550 ℃ to obtain the tin-titanium-silicon molecular sieve.
By XRF composition analysis, the Sn mass percent of the tin-titanium-silicon molecular sieve is 9.6, and the titanium mass percent is 2.5; in an XRD crystal phase diagram, diffraction peaks exist at 5-9 degrees of 2 theta; TEM indicates that 61% of the molecular sieve crystal grains have a cavity structure; in FT-IR, 460cm -1 、800cm -1 、975cm -1 、1080cm -1 Nearby absorption; in UV-Vis, there is absorption at 230-260 nm; a hysteresis loop exists between an adsorption isotherm and a desorption isotherm of low-temperature nitrogen adsorption, the yield of the molecular sieve is 93 percent, the benzene adsorption capacity is 41mg/g, the ratio of an adsorption-desorption difference value to an adsorption capacity (the difference value between the nitrogen adsorption capacity during desorption and the nitrogen adsorption capacity during adsorption of the tin-titanium-silicon molecular sieve is greater than the nitrogen adsorption capacity during adsorption of the tin-titanium-silicon molecular sieve) is 5 percent, and the total specific surface area is 356m 2 (g) an external specific surface area of 51m 2 The proportion of the external specific surface area to the total specific surface area was 14.3%.
Preparation of example 6
In this preparation example, the tin-titanium-silicon molecular sieve is prepared according to the method of CN102452918a catalyst preparation example 1, and the specific preparation method is as follows:
tetraethyl orthosilicate 22.5 g and tetrapropylammonium hydroxide 7.0 g are mixed, and then distilled water 59.8 g is added, after uniform mixing, the mixture is hydrolyzed at normal pressure and 60 ℃ for 1.0 hour to obtain a hydrolysis solution of tetraethyl orthosilicate, a solution consisting of tetrabutyl titanate 1.1 g and anhydrous isopropanol 5.0 g is slowly added under vigorous stirring, and the obtained mixture is stirred at 75 ℃ for 3 hours, and the clear and transparent colloid is obtained. Placing the colloid in a stainless steel sealed reaction kettle, and standing at a constant temperature of 170 ℃ and a self-generated pressure for 6 days to obtain a mixture of crystallized products; the mixture was filtered, washed with water to pH 6-8, and dried at 110 ℃ for 60 minutes to give raw, unfired TS-1 powder. And roasting the TS-1 raw powder for 4 hours at 550 ℃ in an air atmosphere to obtain the TS-1 molecular sieve.
Then TS-1 is uniformly mixed in a system with tetrapropylammonium hydroxide as a template agent and anhydrous stannic chloride as a tin source according to the proportion of (g) molecular sieve to (mol) anhydrous stannic chloride to (mol) tetrapropylammonium hydroxide to (mol) water to (mol) =100: 0.06 x: 0.15: 180, wherein the value of x is the mass percent of stannic oxide in the molecular sieve, the mixture is subjected to a closed autoclave, and 2.2wt percent of tin element calculated by oxide is introduced into an MFI framework through a secondary hydrothermal synthesis method at 140 ℃, so as to obtain the catalyst Sn-TS-1, wherein SnO is SnO-1, and the catalyst is Sn-TS-1 2 2.2wt%, tiO 2 The mass percentage of (B) was 3.9wt%.
Preparation of example 7
The TS-1 molecular sieve obtained in the preparation example 6 is uniformly mixed according to the proportion of the molecular sieve (g): (sulfuric acid (mol):) water (mol) =100: 0.15: 15), reacted for 5.0 hours at 90 ℃, and then filtered, washed and dried according to a conventional method to obtain the acid-treated TS-1 molecular sieve.
The TS-1 molecular sieve treated by the acid is uniformly mixed according to the proportion of the molecular sieve (g), the triethanolamine (mol), the tetrapropylammonium hydroxide (mol) and the water (mol) =100: 0.20: 0.15: 180, the mixture is put into a stainless steel sealed reaction kettle, the stainless steel sealed reaction kettle is placed for 0.5 day at the constant temperature of 190 ℃ and the autogenous pressure, and after cooling and pressure relief, the mixture is filtered, washed and dried according to a conventional method, and is roasted for 3 hours at the temperature of 550 ℃ in an air atmosphere, so that the molecular sieve with the hollow structure is obtained.
The molecular sieve is analyzed by X-ray diffraction to be a titanium-silicon molecular sieve with an MFI structure, a hysteresis ring exists between an adsorption isotherm and a desorption isotherm of low-temperature nitrogen adsorption of the molecular sieve, the crystalline grains are hollow crystalline grains, and the radial length of a cavity part is 15-180 nanometers; the molecular sieve sample had a benzene adsorption of 78 mg/g measured at 25 ℃, P/P0=0.10, and an adsorption time of 1 hour.
Then the molecular sieve with hollow structure is put into a system with the temperature of 140 ℃, tetrapropylammonium hydroxide as a template agent and anhydrous stannic chloride as a tin source according to the weight ratio of the molecular sieveAnhydrous stannic chloride (mol), tetrapropylammonium hydroxide (mol), water (mol) =100: 0.06 x: 0.15: 180 are mixed evenly, the value of x is the mass percent of stannic oxide in a molecular sieve, the mixture is subject to closed autoclave, hydrothermal synthesis is carried out for 72 hours at 140 ℃, 2.1wt% of stannic element calculated by oxide is introduced into MFI framework, catalyst is recorded as Sn-HTS, wherein, calculated by oxide, snO 2 2.1wt%, tiO 2 The mass percentage of (B) is 4.3wt%.
Preparation of comparative example 1
The preparation comparative example is used for preparing the Sn-MFI molecular sieve, and the specific preparation method comprises the following steps:
the pentahydrate stannic chloride (SnCl) 4 .5H 2 O) is dissolved in water, the aqueous solution is added with tetraethyl orthosilicate (TEOS) and stirred, tetrapropylammonium hydroxide (TPAOH, 20% aqueous solution) and water are added with stirring, and the stirring is continued for 30 minutes to obtain the chemical composition of 0.03SnO 2 ：SiO 2 :0.45TPA：35H 2 And crystallizing the clear liquid of O at 433K for 2 days, filtering the obtained solid, washing the solid with distilled water, drying the solid for 5 hours at 393K, and roasting the solid for 10 hours at 823K to obtain a molecular sieve sample. Wherein the dosage of TEOS is 15.31g, the dosage of TPAOH is 33.67g 4 .5H 2 The amount of O was 0.38g and the amount of water was 39.64g.
Preparation of comparative example 2
The present preparation comparative example reference "Nemeth L, moscoso J, erdman N, et al. Synthesis and Catalysis of Sn-Beta as a selective oxidation catalyst [ J ]. Studies in Surface Science & Catalysis,2004,154 (04): 2626-2631" describes the preparation of a Sn-Beta molecular sieve by:
the pentahydrate stannic chloride (SnCl) 4 .5H 2 O) is dissolved in water, the aqueous solution is added to tetraethyl orthosilicate (TEOS) and stirred, tetraethylammonium hydroxide (TEAOH) is added with stirring until TEOS evaporates to give an alcohol, hydrogen Fluoride (HF) is added to the clarified solution, forming a thin paste. Finally, a suspension of dealuminized nano Beta seed crystal (20 nm) and water is added to obtain a chemical composition of 0.03SnO 2 ：SiO 2 ：6TEA：15H 2 O:10HF, then crystallized at the temperature of 413K for 10 days, and then the obtained solid is filtered, washed by distilled water, dried at the temperature of 393K for 5 hours, and then roasted at the condition of 823K for 10 hours to obtain a molecular sieve sample. Wherein the dosage of TEOS is 20.81g, the dosage of TEAOH is 88.42g 4 .5H 2 The amount of O used was 1.05g, the amount of water used was 27.01g, and the amount of HF used was 20g.
Preparation of comparative example 3
This comparative preparation example refers to "Yang X, wu L, wang Z, et al. Conversion of dihydroxy to methyl lactate catalyzed by high active technological Sn-USY at room temperature [ J ]. Catalysis Science & Technology,2016,6 (6): 1757-1763" and the Sn-USY molecular sieve used is prepared by the following method:
mixing an H-USY molecular sieve and nitric acid, treating for 8 hours at 85 ℃, filtering and washing a sample by deionized water, and drying for 12 hours at 120 ℃ to obtain a solid sample. This solid sample was mixed with tin tetrachloride pentahydrate (SnCl) 4 .5H 2 O) for 1 hour to obtain a mixture with a chemical composition of 0.03SnO 2 ：100SiO 2 The mixed liquid is dried for 12 hours at 100 ℃, and finally roasted for 3 hours at 550 ℃ to obtain a molecular sieve sample. Wherein the dosage of H-USY is 2.0g, the dosage of nitric acid is 50mL 4 .5H 2 The amount of O used was 0.6g.
Preparation of comparative example 4
The preparation comparative example is used for preparing the TS-1 molecular sieve, and the specific preparation method comprises the following steps:
tetrapropylammonium hydroxide (TPAOH, 20%) solution in an amount of about 3/4 was added to a tetraethyl orthosilicate (TEOS) solution to obtain a liquid mixture having a pH of about 13, and then a desired amount of n-butyl titanate [ Ti (OBu) ] was added dropwise to the obtained liquid mixture under vigorous stirring 4 ]Stirring the anhydrous isopropanol solution for 15 minutes to obtain a clear liquid, and finally slowly adding the rest TPAOH into the clear liquid, and stirring the mixture for about 3 hours at 348-353K to obtain the anhydrous isopropanol solution with the chemical composition of 0.03TiO 2 ：SiO 2 ：0.36TPA：35H 2 Sol of O, then at 443KAnd crystallizing for 3 days, filtering the obtained solid, washing with distilled water, drying at 373K for 5 hours, and roasting at 823K for 10 hours to obtain a molecular sieve sample. Wherein the amount of TEOS is 42g, the amount of TPAOH is 73g, ti (OBu) 4 The amount of (A) was 2g, the amount of anhydrous isopropyl alcohol was 10g, and the amount of water was 68g.
Preparation of comparative example 5
The preparation comparative example is used for preparing the TS-2 molecular sieve, and the specific preparation method comprises the following steps:
a certain amount of tetrabutylammonium hydroxide solution (TBAOH, 20%) was mixed with tetraethyl orthosilicate (TEOS), and then the desired amount of n-butyl titanate [ Ti (OBu) ] was added dropwise to the resulting clear liquid mixture with vigorous stirring 4 ]Stirring for 30 minutes to obtain a clear liquid after hydrolysis. Finally, 2 times the amount of distilled water required was added and the sol was stirred at 348-353K for 2h to remove the alcohol. The chemical composition of the sol obtained was 0.03TiO 2 ：SiO 2 :0.2TBA：20H 2 And O. And (3) crystallizing the sol at 443K for 3 days, filtering and washing the obtained crystallized product, drying for 6h under 373K, and roasting for 16h under 823K to obtain a molecular sieve sample. Wherein the amount of TEOS is 42g, the amount of TBAOH is 52g, ti (OBu) 4 The amount of (A) was 2g, the amount of anhydrous isopropyl alcohol was 10g, and the amount of water was 30g.
Preparation of comparative example 6
The preparation comparative example is used for preparing the Ti-Beta molecular sieve, and the specific preparation method comprises the following steps:
a certain amount of tetraethyl orthosilicate (TEOS) was added to a solution of metered tetraethylammonium hydroxide solution (TEAOH, 20%) and hydrogen peroxide and hydrolyzed under stirring for 2h. Then weighed tetrabutyl titanate [ Ti (OBu) 4 ]Adding the anhydrous isopropanol solution into hydrolysate of ethyl orthosilicate, continuously stirring for 3h to remove alcohol, and finally obtaining the chemical composition of TiO 2 ：60SiO 2 :33TEA：400H 2 O:20H 2 O 2 The sol of (4). Finally, adding dealuminized P-type molecular sieve seed crystals and stirring vigorously (the seed crystal adding amount is that the sol is calculated by silica, and 4g of seed crystals are added into 100g of silica). The resulting mixtureAfter the compound is crystallized under 413K for 14 days, the obtained slurry is filtered, washed by water, dried under 373K for 6h, and then calcined under 823K for 12h to obtain a molecular sieve sample. Wherein the amount of TEOS is 42g, the amount of TEAOH is 81g, ti (OBu) 4 The dosage of the compound is 1.16g, the dosage of the anhydrous isopropanol is 10g, and the dosage of the hydrogen peroxide is 7.5g.
Preparation of comparative example 7
The hollow titanium silicalite molecular sieve HTS prepared by the preparation comparative example is prepared by the method described in the specification example 1 of the Chinese patent CN1301599A, and the specific preparation method is as follows:
tetraethyl orthosilicate 22.5 g and tetrapropylammonium hydroxide 7.0 g are mixed, and then distilled water 59.8 g is added, after uniform mixing, the mixture is hydrolyzed at 60 ℃ and normal pressure for 1.0 hour to obtain a tetraethyl orthosilicate hydrolyzed solution, a solution consisting of tetrabutyl titanate 1.1 g and anhydrous isopropanol 5.0 g is slowly added under vigorous stirring, and the obtained mixture is stirred at 75 ℃ for 3 hours to obtain a clear and transparent colloid. Placing the colloid in a stainless steel sealed reaction kettle, and standing at a constant temperature of 170 ℃ and a self-generated pressure for 6 days to obtain a mixture of crystallized products; the mixture was filtered, washed with water to pH 6-8, and dried at 110 ℃ for 60 minutes to give raw, unfired TS-1 powder. And roasting the TS-1 raw powder for 4 hours at 550 ℃ in an air atmosphere to obtain the TS-1 molecular sieve.
And (3) uniformly mixing the obtained TS-1 molecular sieve according to the proportion of molecular sieve (g) to sulfuric acid (mol) to water (mol) =100: 0.15: 150, reacting for 5.0 hours at 90 ℃, and then filtering, washing and drying according to a conventional method to obtain the acid-treated TS-1 molecular sieve.
Mixing the acid treated TS-1 molecular sieve uniformly according to the proportion of molecular sieve (g), triethanolamine (mol), tetrapropylammonium hydroxide (mol) and water (mol) =100: 0.20: 0.15: 180, placing the mixture into a stainless steel sealed reaction kettle, placing the stainless steel sealed reaction kettle at the constant temperature of 190 ℃ and the autogenous pressure for 0.5 day, cooling and releasing the pressure, filtering, washing and drying the mixture according to a conventional method, and roasting the mixture for 3 hours at the temperature of 550 ℃ in an air atmosphere to obtain the HTS molecular sieve.
The HTS molecular sieve has a hollow structure with the radial length of 5-100 nanometers, and the benzene adsorption quantity measured by a static adsorption method under the conditions of 25 ℃, P/P0=0.10 and 1 hour of adsorption time is 85 mg/g molecular sieve; the adsorption isotherm and the desorption isotherm of the low-temperature nitrogen adsorption determined according to the standard method of astm d4222-98 show that there is a hysteresis loop between the adsorption isotherm and the desorption isotherm of the low-temperature nitrogen adsorption.
Preparation of comparative example 8
The preparation method of the tin-loaded titanium silicalite Sn/TS-1 in the preparation comparative example is as follows:
the pentahydrate stannic chloride (SnCl) 4 .5H 2 O) and TS-1 molecular sieve (prepared by the method of comparative preparation example 7) are directly and mechanically mixed and then are roasted for 5 hours at 550 ℃ to obtain the molecular sieve with the chemical composition of 0.03TiO 2 :SiO 2 :0.03SnO 2 The molecular sieve of (1). Wherein the dosage of TS-1 is 2g 4 .5H 2 The amount of O used was 0.76g.
Examples and comparative examples are provided to illustrate the preparation of lactic acid using different catalysts to catalyze dihydroxyacetone and/or glyceraldehyde.
Example 1
0.15g of the tin-titanium-silicon molecular sieve Sn-Ti-MFI-1 prepared in preparation example 1 is weighed as a catalyst and filled in a 15mL glass reaction tube, then a magnetic stirrer, 8g of water and 0.1g of dihydroxyacetone are sequentially added, and a cover of the glass reaction tube is screwed on. And putting the glass reaction tube in an oil bath, putting the glass reaction tube on a temperature control magnetic stirrer, and starting the magnetic stirrer and a heating device to start reaction. The reaction temperature is controlled to be about 60 ℃ and the reaction is carried out for 7 hours. The specific reaction results are shown in Table 1.
Comparative example 1
0.15g of the Sn-MFI molecular sieve prepared in preparation comparative example 1 was weighed as a catalyst and placed in a 15mL glass reaction tube, and then a magnetic stirrer, 8g of water and 0.1g of dihydroxyacetone were sequentially added, and the lid of the glass reaction tube was screwed on. And putting the glass reaction tube in an oil bath, putting the glass reaction tube on a temperature control magnetic stirrer, and starting the magnetic stirrer and a heating device to start reaction. The reaction temperature is controlled to be about 60 ℃ and the reaction is carried out for 7 hours. The specific reaction results are shown in Table 1.
Comparative example 2
0.15g of the Sn-Beta molecular sieve prepared in the preparation comparative example 2 is weighed and taken as a catalyst to be filled in a 15mL glass reaction tube, then a magnetic stirrer, 8g of water and 0.1g of dihydroxyacetone are sequentially added, and the cover of the glass reaction tube is screwed on. And putting the glass reaction tube in an oil bath, putting the glass reaction tube on a temperature control magnetic stirrer, and starting the magnetic stirrer and a heating device to start reaction. The reaction temperature is controlled to be about 60 ℃ and the reaction is carried out for 7 hours. The specific reaction results are shown in Table 1.
Comparative example 3
0.15g of the Sn-USY molecular sieve prepared in the preparation comparative example 3 is weighed and loaded into a 15mL glass reaction tube as a catalyst, then a magnetic stirrer, 8g of water and 0.1g of dihydroxyacetone are sequentially added, and the cover of the glass reaction tube is screwed on. And putting the glass reaction tube in an oil bath, putting the glass reaction tube on a temperature control magnetic stirrer, and starting the magnetic stirrer and a heating device to start reaction. The reaction temperature is controlled to be about 60 ℃ and the reaction is carried out for 7 hours. The specific reaction results are shown in Table 1.
Comparative example 4
0.15g of the titanium silicalite molecular sieve TS-2 prepared in the preparation comparative example 5 is weighed and taken as a catalyst to be filled in a 15mL glass reaction tube, then a magnetic stirrer, 8g of water and 0.1g of dihydroxyacetone are sequentially added, and the cover of the glass reaction tube is screwed on. And putting the glass reaction tube in an oil bath, putting the glass reaction tube on a temperature control magnetic stirrer, and starting the magnetic stirrer and a heating device to start reaction. The reaction temperature is controlled to be about 60 ℃ and the reaction is carried out for 7 hours. The specific reaction results are shown in Table 1.
Comparative example 5
Weighing 0.15g of the Ti-Si molecular sieve Ti-Beta prepared in the preparation comparative example 6 as a catalyst, putting the catalyst into a 15mL glass reaction tube, sequentially adding a magnetic stirrer, 8g of water and 0.1g of dihydroxyacetone, and screwing a cover of the glass reaction tube. And putting the glass reaction tube in an oil bath, putting the glass reaction tube on a temperature control magnetic stirrer, and starting the magnetic stirrer and a heating device to start reaction. The reaction temperature is controlled to be about 60 ℃ and the reaction is carried out for 7 hours. The specific reaction results are shown in Table 1.
Comparative example 6
Weighing 0.15g of the titanium silicalite TS-1 prepared in the preparation comparative example 4 as a catalyst, putting the catalyst into a 15mL glass reaction tube, sequentially adding a magnetic stirrer, 8g of water and 0.1g of glyceraldehyde, and screwing the cover of the glass reaction tube. And (3) placing the glass reaction tube in an oil bath, placing the glass reaction tube on a temperature control magnetic stirrer, starting the magnetic stirrer and a heating device, and starting the reaction. The reaction temperature is controlled to be about 60 ℃ and the reaction is carried out for 0.5 hour. The specific reaction results are shown in Table 1.
Comparative example 7
0.10g of the Sn-MFI molecular sieve prepared in the preparation comparative example 1 and 0.05g of the TS-1 molecular sieve prepared in the preparation comparative example 4 are weighed as catalysts and filled in a 15mL glass reaction tube, then a magnetic stirrer, 8g of water and 0.1g of dihydroxyacetone are sequentially added, and the cover of the glass reaction tube is screwed on. And putting the glass reaction tube in an oil bath, putting the glass reaction tube on a temperature control magnetic stirrer, and starting the magnetic stirrer and a heating device to start reaction. The reaction temperature is controlled to be about 60 ℃ and the reaction is carried out for 7 hours. The specific reaction results are shown in Table 1.
Comparative example 8
0.05g of the Sn-MFI molecular sieve prepared in the preparation comparative example 1 and 0.10g of the TS-1 molecular sieve prepared in the preparation comparative example 4 are weighed as catalysts and filled in a 15mL glass reaction tube, then a magnetic stirrer, 8g of water and 0.1g of dihydroxyacetone are sequentially added, and the cover of the glass reaction tube is screwed on. And putting the glass reaction tube in an oil bath, putting the glass reaction tube on a temperature control magnetic stirrer, and starting the magnetic stirrer and a heating device to start reaction. The reaction temperature is controlled to be about 60 ℃ and the reaction is carried out for 7 hours. The specific reaction results are shown in Table 1.
Comparative example 9
0.15g of the tin-titanium-silicon molecular sieve Sn-Ti-MFI-4 prepared in preparation example 4 is weighed as a catalyst and filled in a 15mL glass reaction tube, then a magnetic stirrer, 8g of water and 0.1g of dihydroxyacetone are sequentially added, and a cover of the glass reaction tube is screwed on. And putting the glass reaction tube in an oil bath, putting the glass reaction tube on a temperature control magnetic stirrer, and starting the magnetic stirrer and a heating device to start reaction. The reaction temperature is controlled to be about 10 ℃ and the reaction is carried out for 0.5 hour. The specific reaction results are shown in Table 1.
Comparative example 10
0.15g of the hollow titanium silicalite molecular sieve HTS catalyst prepared in the preparation comparative example 7 is weighed and placed in a 15mL glass reaction tube, then a magnetic stirrer, 8g of water and 0.1g of dihydroxyacetone are sequentially added, and the cover of the glass reaction tube is screwed on. And putting the glass reaction tube in an oil bath, putting the glass reaction tube on a temperature control magnetic stirrer, and starting the magnetic stirrer and a heating device to start reaction. The reaction temperature is controlled at about 60 ℃ and the reaction is carried out for 7 hours. The specific reaction results are shown in Table 1.
Comparative example 11
0.15g of the Sn/TS-1 catalyst of the Sn-loaded titanium silicalite molecular sieve prepared in the preparation comparative example 8 is weighed and loaded in a 15mL glass reaction tube, then a magnetic stirrer, 8g of water and 0.1g of dihydroxyacetone are sequentially added, and the cover of the glass reaction tube is screwed on. And putting the glass reaction tube in an oil bath, putting the glass reaction tube on a temperature control magnetic stirrer, and starting the magnetic stirrer and a heating device to start reaction. The reaction temperature is controlled to be about 60 ℃ and the reaction is carried out for 7 hours. The specific reaction results are shown in Table 1.
Comparative example 12
The same as example 1 except that: the reaction temperature is 200 ℃, the reaction time is 12 hours, the reaction raw materials and the catalyst are filled in a polytetrafluoroethylene lining, then the polytetrafluoroethylene lining is placed in a stainless steel reaction kettle for sealing, and the reaction is carried out in a homogeneous reactor. The specific reaction results are shown in Table 1.
Example 2
0.15g of the tin-titanium-silicon molecular sieve Sn-Ti-MFI-2 prepared in preparation example 2 is weighed and loaded into a 15mL glass reaction tube as a catalyst, then a magnetic stirrer, 8g of water and 0.1g of glyceraldehyde are sequentially added, and a cover of the glass reaction tube is screwed on. And putting the glass reaction tube in an oil bath, putting the glass reaction tube on a temperature control magnetic stirrer, and starting the magnetic stirrer and a heating device to start reaction. The reaction temperature is controlled to be about 60 ℃ and the reaction is carried out for 7 hours. The specific reaction results are shown in Table 1.
Example 3
0.15g of the tin-titanium-silicon molecular sieve Sn-Ti-MFI-3 prepared in preparation example 3 was weighed as a catalyst and placed in a 15mL glass reaction tube, and then a magnetic stirrer, 8g of water and 0.1g of dihydroxyacetone were sequentially added, and a cover of the glass reaction tube was screwed on. And putting the glass reaction tube in an oil bath, putting the glass reaction tube on a temperature control magnetic stirrer, and starting the magnetic stirrer and a heating device to start reaction. The reaction temperature is controlled to be about 60 ℃ and the reaction is carried out for 7 hours. The specific reaction results are shown in Table 1.
Example 4
0.15g of the tin-titanium-silicon molecular sieve Sn-Ti-MFI-4 prepared in preparation example 4 is weighed and loaded into a 15mL glass reaction tube as a catalyst, then a magnetic stirrer, 8g of water and 0.1g of glyceraldehyde are sequentially added, and a cover of the glass reaction tube is screwed on. And putting the glass reaction tube in an oil bath, putting the glass reaction tube on a temperature control magnetic stirrer, and starting the magnetic stirrer and a heating device to start reaction. The reaction temperature is controlled to be about 60 ℃ and the reaction is carried out for 7 hours. The specific reaction results are shown in Table 1.
Example 5
0.15g of the tin-titanium-silicon molecular sieve Sn-Ti-MFI-5 prepared in preparation example 5 is weighed as a catalyst and filled in a 15mL glass reaction tube, then a magnetic stirrer, 8g of water and 0.1g of dihydroxyacetone are sequentially added, and a cover of the glass reaction tube is screwed on. And putting the glass reaction tube in an oil bath, putting the glass reaction tube on a temperature control magnetic stirrer, and starting the magnetic stirrer and a heating device to start reaction. The reaction temperature is controlled to be about 60 ℃ and the reaction is carried out for 7 hours. The specific reaction results are shown in Table 1.
Example 6
The same as example 1 except that the tin-titanium-silicon molecular sieve provided in preparation example 6 was used as a catalyst. The specific reaction results are shown in Table 1.
Example 7
The same as example 1 except that the tin-titanium-silicon molecular sieve provided in preparation example 7 was used as a catalyst. The specific reaction results are shown in Table 1.
Example 8
The same as example 1 except that: the molar ratio of dihydroxyacetone to water is 1:50 at 30 deg.c for 1 hr, and the weight ratio of dihydroxyacetone to Sn-Ti-Si molecular sieve is 1:1. The specific reaction results are shown in Table 1.
Example 9
The same as example 1 except that: the molar ratio of dihydroxyacetone to water is 1:450, the reaction temperature is 180 ℃, the reaction time is 10 hours, the weight ratio of the dihydroxyacetone to the tin-titanium-silicon molecular sieve is 1:6, the reaction raw materials and the catalyst are filled into a polytetrafluoroethylene lining, and then the polytetrafluoroethylene lining is placed into a stainless steel reaction kettle to be sealed and reacted in a homogeneous reactor. The specific reaction results are shown in Table 1.
Example 10
Essentially the same as in example 1 except that dihydroxyacetone was replaced with an equimolar mixture of dihydroxyacetone and glyceraldehyde, the molar ratio of dihydroxyacetone to glyceraldehyde in the mixture being 1:1. The specific reaction results are shown in Table 1.
As can be seen from the results of the above examples and comparative examples, the method of the present invention for preparing lactic acid has the advantages of simple operation process, mild reaction conditions, high conversion rate of raw materials and high selectivity of lactic acid; especially when the catalyst is a binary tin titanium silicon molecular sieve, the molar ratio of dihydroxyacetone and/or glyceraldehyde to water is 1: (50-450), the reaction temperature is 30-180 ℃, the reaction time is 1-10h, the reaction pressure is 0.1-3.0MPa, and the weight ratio of the weight of dihydroxyacetone and/or glyceraldehyde to the weight of the tin-titanium-silicon molecular sieve based on the dry weight is 1: in the case of (1-6), it is more preferable that the molar ratio of dihydroxyacetone and/or glyceraldehyde to water is in the range of 1: (60-200), the reaction temperature is 40-120 ℃, the reaction time is 2-8h, the reaction pressure is 0.1-2.0MPa, and the weight ratio of the weight of dihydroxyacetone and/or glyceraldehyde to the weight of the tin-titanium-silicon molecular sieve based on the dry weight is 1: (1.2-3), the conversion rate of dihydroxyacetone/glyceraldehyde and the yield of lactic acid are improved.
The preferred embodiments of the present invention have been described in detail, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.
It should be noted that the various technical features described in the above embodiments can be combined in any suitable manner without contradiction, and the invention is not described in any way for the possible combinations in order to avoid unnecessary repetition.
In addition, any combination of the various embodiments of the present invention is also possible, and the same should be considered as the content of the present invention as long as it does not depart from the gist of the present invention.
TABLE 1
Numbering Dihydroxyacetone/glyceraldehyde conversion/% ] Lactic acid selectivity/%)
Example 1 99 99
Example 2 95 99
Example 3 95 98
Example 4 96 95
Example 5 98 98
Example 6 95 96
Example 7 97 96
Example 8 95 98
Example 9 99 95
Example 10 96 97
Comparative example 1 81 75
Comparative example 2 80 74
Comparative example 3 80 71
Comparative example 4 43 60
Comparative example 5 42 61
Comparative example 6 43 60
Comparative example 7 87 91
Comparative example 8 89 90
Comparative example 9 32 31
Comparative example 10 60 65
Comparative example 11 63 54
Comparative example 12 97 64

Claims (11)

1. A method of catalyzing dihydroxyacetone and/or glyceraldehyde to produce lactic acid, the method comprising:
contacting reaction raw materials, water and a catalyst in a reactor and carrying out reaction to obtain a product containing lactic acid; wherein:
the reaction raw materials contain dihydroxyacetone and/or glyceraldehyde, and the molar ratio of dihydroxyacetone and/or glyceraldehyde: water =1: (50-450), the reaction temperature is 30-180 ℃, the reaction time is 1-10h, the catalyst contains a tin-titanium-silicon molecular sieve, and the weight ratio of the weight of dihydroxyacetone and/or glyceraldehyde to the weight of the tin-titanium-silicon molecular sieve on a dry basis is 1: (1-6); the tin-titanium-silicon molecular sieve is selected from an MFI type tin-titanium-silicon molecular sieve; the molar ratio of tin element to silicon element in the tin-titanium-silicon molecular sieve is 0.05-10.
2. The method of claim 1, wherein the tin-titanium-silicon molecular sieve is selected from Sn-Ti-MFI molecular sieves.
3. The method of claim 1, wherein the tin-titanium-silicon molecular sieve contains elemental silicon, elemental titanium, elemental tin, and elemental oxygen;
at least part of crystal grains of the tin-titanium-silicon molecular sieve have a cavity structure;
the proportion of the external specific surface area of the tin-titanium-silicon molecular sieve in the total specific surface area is more than 10 percent, and the total specific surface area is 300m 2 More than g, and the external specific surface area is 20m 2 More than g;
the tin-titanium-silicon molecular sieve has a diffraction peak at 0.5-9 degrees of 2 theta in an XRD pattern;
460cm of the tin-titanium-silicon molecular sieve in an FT-IR spectrum -1 、975cm -1 、800cm -1 And 1080cm -1 Nearby absorption;
the tin-titanium-silicon molecular sieve has absorption at 200-300nm in a UV-Vis spectrum;
the tin-titanium-silicon molecular sieve is P/P at 25 DEG C 0 An adsorbed amount of benzene of at least 35mg/g as measured under conditions of 0.10 and an adsorption time of 1 hour; at a relative pressure P/P 0 If the molar ratio is about 0.60, the difference between the nitrogen adsorption amount during desorption and the nitrogen adsorption amount during adsorption of the tin-titanium-silicon molecular sieve is greater than 2% of the nitrogen adsorption amount during adsorption of the tin-titanium-silicon molecular sieve;
a hysteresis loop exists between the adsorption isotherm and the desorption isotherm of the low-temperature nitrogen adsorption of the tin-titanium-silicon molecular sieve;
the radial length of the cavity part of the cavity structure in the crystal grain of the tin-titanium-silicon molecular sieve is 0.5-300nm.
4. The method of claim 3, whichIn the method, the ratio of the external specific surface area of the tin-titanium-silicon molecular sieve to the total specific surface area is 10-25%, and the total specific surface area is 310-600m 2 Per g, external specific surface area of 31-150m 2 /g。
5. The method of claim 1, wherein the method of preparing the tin-titanium-silicon molecular sieve comprises:
(1) Contacting a tin source, a titanium source and a template agent in the presence of an aqueous solvent to obtain a first mixture;
(2) Mixing the first mixture with a silicon molecular sieve to obtain a second mixture;
(3) And crystallizing the second mixture under the hydrothermal crystallization condition.
6. The method of claim 5, wherein in step (1), the contacting conditions comprise: the contact temperature is 20-80 ℃, and the contact time is 1-240min;
the dosage of the silicon molecular sieve and the tin source ensures that the molar ratio of tin element to silicon element in the prepared tin-titanium-silicon molecular sieve is 0.05-10; the dosage of the silicon molecular sieve and the titanium source ensures that the molar ratio of the titanium element to the silicon element in the prepared tin-titanium-silicon molecular sieve is 0.05-10;
the dosage mole ratio of the silicon molecular sieve, the template agent, the titanium source, the tin source and the water is (100) 2 The tin source is calculated by tin element, and the titanium source is calculated by TiO 2 Counting;
the hydrothermal crystallization conditions include: the crystallization temperature is 80-200 ℃ under the closed condition, and the crystallization time is 6-150h;
the tin source is an inorganic tin compound and/or an organic tin compound; the titanium source is an inorganic titanium compound and/or an organic titanium compound; the template agent is one or more of aliphatic amine compound, aliphatic alcohol amine compound and quaternary ammonium base compound; the silicon molecular sieve is one or more selected from S-1, S-2, BETA, MOR, MCM-22, MCM-41, SBA-15 and MCM-48;
at least of the tin-titanium-silicon molecular sieveA cavity structure is arranged in part of the crystal grains, and a diffraction peak is arranged at the position of 0.5-9 degrees of 2 theta in an XRD pattern; 460cm in the FT-IR spectrum -1 、975cm -1 、800cm -1 、1080cm -1 Nearby absorption; the absorption is carried out at 200-300nm in a UV-Vis spectrum, and the total specific surface area of the tin-titanium-silicon molecular sieve is 300m 2 More than g, and the external specific surface area is 30m 2 More than g, and the proportion of the external specific surface area in the total specific surface area is more than 10 percent.
7. The method of claim 1, wherein the tin-titanium-silicon molecular sieve is obtained by performing a second hydrothermal synthesis on a titanium-silicon molecular sieve with a compound containing a tin source, a template agent, alkali and water at 100-160 ℃, and performing filtering separation, drying and roasting, wherein the tin content of the molecular sieve is 1-5 wt% calculated by oxide;
the tin-titanium-silicon molecular sieve is one or more of Sn-TS-1, sn-TS-2, sn-Ti-BETA, sn-Ti-MCM-22, sn-Ti-MCM-41 and Sn-Ti-MCM-48.
8. The method of claim 7, wherein the Sn-TS-1 is a titanium silicalite molecular sieve having an MFI crystal structure, the grains have a hollow structure, and the radial length of the hollow part of the hollow grains is 5 to 300nm; the molecular sieve sample is at 25 ℃ and P/P 0 =0.10, the benzene adsorption amount measured under the condition of adsorption time of 1 hour is at least 70 mg/g, and a hysteresis loop exists between the adsorption isotherm and the desorption isotherm of low-temperature nitrogen adsorption of the molecular sieve.
9. The method of claim 1, wherein, on a molar basis, the molar ratio of dihydroxyacetone and/or glyceraldehyde: water =1: (60-200), the weight ratio of the dihydroxyacetone and/or glyceraldehyde to the weight of the tin-titanium-silicon molecular sieve on a dry basis is 1: (1.2-3), the reaction temperature is 40-120 ℃, the reaction time is 2-8h, and the reaction pressure is 0.1-3MPa.
10. The process according to claim 9, wherein the reaction pressure is 0.1-2MPa.
11. The process of claim 1, wherein the reactor is a tank reactor, a fixed bed reactor, a moving bed, a suspended bed, or a slurry bed reactor.
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