CN111253245A - Method for preparing lactic acid - Google Patents

Method for preparing lactic acid Download PDF

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CN111253245A
CN111253245A CN201811459256.3A CN201811459256A CN111253245A CN 111253245 A CN111253245 A CN 111253245A CN 201811459256 A CN201811459256 A CN 201811459256A CN 111253245 A CN111253245 A CN 111253245A
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molecular sieves
tin
molecular sieve
titanium silicalite
silicon
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CN111253245B (en
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刘聿嘉
王亚敏
夏长久
朱斌
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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Sinopec Research Institute of Petroleum Processing
China Petroleum and Chemical Corp
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J29/00—Catalysts comprising molecular sieves
    • B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
    • B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
    • B01J29/70—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of types characterised by their specific structure not provided for in groups B01J29/08 - B01J29/65
    • B01J29/7049—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of types characterised by their specific structure not provided for in groups B01J29/08 - B01J29/65 containing rare earth elements, titanium, zirconium, hafnium, zinc, cadmium, mercury, gallium, indium, thallium, tin or lead
    • 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
    • C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
    • C07C45/56—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds from heterocyclic compounds
    • C07C45/57—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds from heterocyclic compounds with oxygen as the only heteroatom
    • C07C45/60—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds from heterocyclic compounds with oxygen as the only heteroatom in six-membered rings
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • 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
    • B01J2229/183—After treatment, characterised by the effect to be obtained to introduce other elements into or onto the molecular sieve itself in framework positions

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Abstract

The present invention relates to a method for preparing lactic acid, comprising: contacting sugar and water with a catalyst in a reactor and carrying out reaction to obtain a product containing lactic acid; wherein the molar ratio of sugar to water is 1: (50-1600) the reaction temperature is 150-250 ℃, the reaction time is 10-50h, the catalyst contains a mixture of titanium silicalite and tin silicalite, and the weight ratio of sugar to the mixture of titanium silicalite and tin silicalite on a dry basis weight is 1: (0.1-6). The process of the invention has high sugar conversion and lactic acid yield.

Description

Method for preparing lactic acid
Technical Field
The present invention relates to a method for preparing lactic acid.
Background
Lactic acid (2-hydroxypropionic acid, scientific name) is a compound that functions in a variety of biochemical processes, and has the molecular formula C3H6O3It is a carboxylic acid containing hydroxyl group, therefore an α -hydroxy acid, its carboxyl group releases a proton in aqueous solution to produce lactate ion during fermentation process lactate dehydrogenase converts pyruvate to levolactic acid, lactic acid is continuously produced in general metabolism and movement, but its concentration does not generally rise, lactic acid is colorless liquid, industrial product is colorless to pale yellow liquid, odorless, hygroscopic, relative density 1.200, melting point 18 ℃, boiling point 122 ℃, flash point greater than 110 ℃, miscible with ethanol, diethyl ether, water, glycerol, insoluble in chloroform, carbon disulfide and petroleum ether, widely used in food industry, pharmaceutical industry, cosmetics industry, agriculture 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 obtain crude lactic acid, while producing a large amount of waste salt (calcium sulphate). However, crude lactic acid is difficult to separate and needs to be reacted with alcohol to produce lactate with a relatively low boiling point, and then subjected to distillation separation and hydrolysis reaction to obtain high-purity lactic acid. The reaction route of the process is long, the production cost is high, and a large amount of solid waste residue is generated, so that the 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 object of the present invention is to provide a process for producing lactic acid with high conversion of sugar and yield of lactic acid.
In order to achieve the above object, the present invention provides a method for preparing lactic acid, comprising:
contacting sugar and water with a catalyst in a reactor and carrying out reaction to obtain a product containing lactic acid; wherein the molar ratio of sugar to water is 1: (50-1600) the reaction temperature is 150-250 ℃, the reaction time is 10-50h, the catalyst contains a mixture of titanium silicalite and tin silicalite, and the weight ratio of sugar to the mixture of titanium silicalite and tin silicalite on a dry basis weight is 1: (0.1-6).
Optionally, the tin-silicon molecular sieve is selected from one or more of an MFI type tin-silicon molecular sieve, an MEL type tin-silicon molecular sieve, a BEA type tin-silicon molecular sieve, an MWW type tin-silicon molecular sieve, an MOR type tin-silicon molecular sieve, a hexagonal structure tin-silicon molecular sieve and an FAU type tin-silicon molecular sieve.
Optionally, the titanium silicalite molecular sieve is selected from one or more of an MFI type titanium silicalite molecular sieve, an MEL type titanium silicalite molecular sieve, a BEA type titanium silicalite molecular sieve, an MWW type titanium silicalite molecular sieve, an MOR type titanium silicalite molecular sieve, a TUN type titanium silicalite molecular sieve and a hexagonal structure titanium silicalite molecular sieve.
Optionally, the tin-silicon molecular sieve is selected from one or more of Sn-MFI molecular sieve, Sn-MEL molecular sieve, Sn-Beta molecular sieve, Sn-MCM-22 molecular sieve, Sn-MOR molecular sieve, Sn-MCM-41 molecular sieve, Sn-SBA-15 molecular sieve and Sn-USY molecular sieve.
Optionally, the titanium silicalite molecular sieve is selected from one or more of a TS-1 molecular sieve, a TS-2 molecular sieve, a Ti-Beta molecular sieve, a Ti-MCM-22 molecular sieve, a Ti-MOR molecular sieve, a Ti-TUN molecular sieve, a Ti-MCM-41 molecular sieve, a Ti-SBA-15 molecular sieve and a Ti-ZSM-48 molecular sieve.
Optionally, the weight ratio of the titanium-silicon molecular sieve to the tin-silicon molecular sieve in the catalyst is 1: (0.1-10).
Optionally, the molar ratio of titanium dioxide to silicon dioxide in the titanium silicalite molecular sieve is (0.01-10): 100, preferably (0.05-5): 100;
the molar ratio of tin dioxide to silicon dioxide in the tin-silicon molecular sieve is (0.01-10): 100, preferably (0.05-5): 100.
Optionally, the sugar is one or more selected from the group consisting of pentoses, hexoses and disaccharides, the pentoses are xylose, the hexoses are one or more selected from the group consisting of glucose, fructose and mannose, and the disaccharides are sucrose.
Optionally, the molar ratio of sugar to water is 1: (100-1000), the weight ratio of the sugar to the mixture of the titanium silicalite molecular sieves and the tin silicalite molecular sieves is 1: (0.2-3), the reaction temperature is 155-220 ℃, the reaction time is 12-40h, the reaction pressure is 0.1-6MPa, and the reaction pressure is preferably 0.1-4 MPa.
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 mixture of the tin-silicon molecular sieve and the titanium-silicon molecular sieve, the framework tin atom of the tin-silicon molecular sieve catalyzes sugar to generate the aldol condensation reaction to generate dihydroxyacetone, the ketocarbonyl in the dihydroxyacetone is further activated to generate the methylglyoxal, the framework titanium atom of the titanium-silicon molecular sieve and the framework tin atom of the tin-silicon molecular sieve cooperatively catalyze the methylglyoxal to generate the lactic acid, and the reaction efficiency is improved. Compared with the prior art, higher sugar conversion rate and lactic acid yield can be obtained in a short time under mild reaction conditions, the subsequent separation energy consumption of the product is lower, the process is safer and more efficient, and the method 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.
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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 of the conversion of sugar 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 refers to the weight measured after the sample is baked at 550 ℃ for 3 hours.
The present invention provides a method for preparing lactic acid, comprising: contacting sugar and water with a catalyst in a reactor and carrying out reaction to obtain a product containing lactic acid; wherein the molar ratio of sugar to water is 1: (50-1600) the reaction temperature is 150-250 ℃, the reaction time is 10-50h, the catalyst contains a mixture of titanium silicalite and tin silicalite, and the weight ratio of sugar to the mixture of titanium silicalite and tin silicalite on a dry basis weight is 1: (0.1-6). The reaction mechanism is shown in figure 1.
According to the invention, the tin-silicon molecular sieve is a molecular sieve obtained by replacing a part of silicon atoms in a lattice framework of the molecular sieve with tin atoms, the titanium-silicon molecular sieve is a molecular sieve obtained by replacing a part of silicon atoms in a lattice framework of the molecular sieve with titanium atoms, and a mechanical mixture obtained by mechanically mixing the two molecular sieves is used as a catalyst or a component of the catalyst. The tin and titanium atom content of the molecular sieve may be determined by XRF methods conventional in the artThe tin atoms and the titanium atoms in the framework of the molecular sieve can be measured by adopting an ultraviolet spectrum or an infrared spectrum, for example, the ultraviolet spectrum is used for analyzing a tin-silicon molecular sieve sample, and the characteristic absorption peak of the framework tin atoms appears at the vicinity of 190 nm; when a titanium silicalite molecular sieve sample is analyzed, a characteristic absorption peak of a framework Ti atom appears near 210 nm. Pyridine infrared spectrum at 1450cm-1The peaks of (a) represent the L-acidic character of the molecular sieve, provided by framework tin atoms and framework titanium atoms.
According to the invention, the tin-silicon molecular sieve is a product of tin atoms replacing part of framework silicon of various topological structure molecular sieves, the topological structure of the molecular sieve can refer to the website of International Zeolite Association (IZA), for example, the tin-silicon molecular sieve can be selected from one or more of MFI type tin-silicon molecular sieve, MEL type tin-silicon molecular sieve, BEA type tin-silicon molecular sieve, MWW type tin-silicon molecular sieve, MOR type tin-silicon molecular sieve, hexagonal structure tin-silicon molecular sieve and FAU type tin-silicon molecular sieve. The MFI type tin-silicon molecular sieve is Sn-MFI molecular sieve, MEL type tin-silicon molecular sieve is Sn-MEL molecular sieve, BEA type tin-silicon molecular sieve is Sn-Beta molecular sieve, MWW type tin-silicon molecular sieve is Sn-MCM-22 molecular sieve, MOR type tin-silicon molecular sieve is Sn-MOR molecular sieve, hexagonal structure tin-silicon molecular sieve is Sn-MCM-41 molecular sieve, Sn-SBA-15 molecular sieve, FAU type tin-silicon molecular sieve is Sn-USY molecular sieve. Specific preparation methods of the tin-silicon molecular sieve can refer to Chinese patents CN104549549A, CN107162014A, CN105271294A, CN103964461A, CN105314649A, CN104557629A, CN104557632A, CN103204806A, CN103204830A, CN103204775A, CN103204792A, CN103204777A, CN103204835A and the like. Further preferably, the tin-silicon molecular sieve is an MFI-type tin-silicon molecular sieve. The MFI-type tin-silicon molecular sieves are commercially available or can be prepared according to the methods of the literature (Mal N K, Ramasumamy V, Rajamohanan P R, et al. Sn-MFI molecular sieves: synthesis methods,29Si liquid and solid MAS-NMR,119Sn static and MAS NMRstudies [ J ]. Micropore Materials,1997,12(4-6):331 and 340).
According to the invention, the titanium silicalite molecular sieve is a product of titanium atoms replacing part of framework silicon of molecular sieves with various topological structures, and the titanium silicalite molecular sieve can be one or more selected from MFI type titanium silicalite molecular sieve, MEL type titanium silicalite molecular sieve, BEA type titanium silicalite molecular sieve, MWW type titanium silicalite molecular sieve, MOR type titanium silicalite molecular sieve, TUN type titanium silicalite molecular sieve and hexagonal structure titanium silicalite molecular sieve. The MFI type titanium silicalite molecular sieve is TS-1 molecular sieve, MEL type titanium silicalite molecular sieve is TS-2 molecular sieve, BEA type titanium silicalite molecular sieve is Ti-Beta molecular sieve, MWW type titanium silicalite molecular sieve is Ti-MCM-22 molecular sieve, MOR type titanium silicalite molecular sieve is Ti-MOR molecular sieve, TUN type titanium silicalite molecular sieve is Ti-TUN molecular sieve, hexagonal structure titanium silicalite molecular sieve is Ti-MCM-41 molecular sieve, Ti-SBA-15 molecular sieve, other structure titanium silicalite molecular sieve is Ti-ZSM-48 molecular sieve. Specific preparation methods of the titanium silicalite molecular sieve can refer to chinese patents CN107879357A, CN107879354A, CN107879356A, CN107879355A, CN107986293A, CN107986294A, CN108002404A, CN107539999A, CN107537559A, CN107539998A, CN103182323A, CN103183355A, CN106964400A, CN106904633A, CN107986292A, CN103182320A, CN103182322A, CN103183356A, CN101439300A, CN106145151A, CN107840347A, CN106145148A, CN106145149A, CN106145147A, and CN107840344A, etc., preferably, the titanium silicalite molecular sieve is at least one selected from MFI type titanium silicalite molecular sieve, MEL type titanium silicalite molecular sieve, and BEA type titanium silicalite molecular sieve. Further preferably, the titanium silicalite molecular sieve is an MFI-type titanium silicalite molecular sieve. The MFI-type titanium silicalite molecular sieves are commercially available or can be prepared according to literature procedures (Studieson the synthesis of titanium silicalite, TS-1Zeolite, 1992,12(8), 943-50).
According to the invention, the skeleton titanium atom of the titanium silicalite molecular sieve and the skeleton tin atom of the tin silicalite molecular sieve cooperate to catalyze sugar to generate lactic acid, the titanium silicalite molecular sieve and the tin silicalite molecular sieve in the catalyst can be mixed in any proportion, preferably, the mixing weight ratio of the titanium silicalite molecular sieve to the tin silicalite molecular sieve in the catalyst is 1: (0.001-1000), and further preferably, the mixing weight ratio of the titanium silicalite molecular sieves and the tin silicalite molecular sieves in the catalyst is 1: (0.01-100), and more preferably, the mixing weight ratio of the titanium silicalite molecular sieves and the tin silicalite molecular sieves in the catalyst is 1: (0.1-10).
According to the present invention, titanium atoms and tin atoms may be substituted for a portion of the silicon atoms in the molecular sieve, for example, the titanium silicalite may have a molar ratio of titania to silica of (0.01-10): 100, preferably (0.05-5): 100; the molar ratio of tin dioxide to silicon dioxide in the tin-silicon molecular sieve can be (0.01-10): 100, preferably (0.05-5): 100.
According to the present invention, the sugar is well known to those skilled in the art, for example, the sugar is one or more selected from the group consisting of a pentose, a hexose, and a disaccharide, the pentose is xylose, the hexose is one or more selected from the group consisting of glucose, fructose, and mannose, and the disaccharide is sucrose.
According to the invention, the molar ratio of sugar to water is preferably 1: (100-1000), the weight ratio of sugar to the mixture of titanium silicalite and tin silicalite on a dry basis is preferably 1: (0.2-3), the reaction temperature is preferably 155-220 ℃, the reaction time is preferably 12-40h, the reaction pressure (absolute pressure) is 0.1-6MPa, and the reaction pressure is preferably 0.1-4 MPa.
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-silicon molecular sieve and/or the titanium-silicon molecular sieve of the present invention may be raw molecular sieve powder, or may be 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 lactic acid in the activity evaluation system is analyzed by adopting gas chromatography, the sugar in the activity evaluation system is analyzed by adopting liquid chromatography, the analysis result is quantified by adopting an internal standard method, and the internal standard substance is naphthalene. Wherein, the analysis conditions of the gas chromatography 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 3 min. FID detector, detector temperature 300 ℃. The analysis conditions of the liquid chromatography were: an Agilent-1200 type chromatograph, an Aminex HPX-87H chromatographic column, a column temperature of 60 ℃, a differential refraction detector, 0.005M sulfuric acid as a mobile phase and a flow rate of 0.5 mL/min.
In each of the examples and comparative examples:
percent conversion of sugars ═ mole of sugars in the feed-mole of sugars in the product)/mole of sugars in the feed × 100%;
lactic acid selectivity:% lactic acid moles in product/(moles of sugars in starting material-moles of sugars in product) × 100%;
the lactic acid yield (% lactic acid) is the number of moles of lactic acid in the product/moles of sugar in the raw material × 100%, i.e., the lactic acid yield (% lactic acid selectivity × sugar conversion).
Preparation examples and preparation comparative examples catalysts used in the examples and comparative examples were provided.
Preparation of example 1
The preparation method for preparing the Sn-MFI molecular sieve comprises the following steps:
the pentahydrate stannic chloride (SnCl)4.5H2O) 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 0.03SnO2：SiO2:0.45TPA：35H2And 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 amount of TEOS is 15.31g, the amount of TPAOH is 33.67g, and SnCl4.5H2The amount of O was 0.38g and the amount of water was 39.64 g.
Preparation of example 2
The Sn-Beta molecular sieve is prepared by the method of the reference literature, "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-:
the pentahydrate stannic chloride (SnCl)4.5H2O) dissolving in water, adding tetraethyl orthosilicate (TEOS) into the water solution, stirring, adding tetraethyl ammonium hydroxide (TEAOH) while stirring, stirring until TEOS is evaporated to obtain alcohol, and adding Hydrogen Fluoride (HF) into the clear solution to form a paste thin layer. Finally adding a suspension of dealuminized nano Beta seed crystal (20nm) and water to obtain the product with the chemical composition of 0.03SnO2：SiO2：6TEA：15H2O: 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 amount of TEOS is 20.81g, the amount of TEAOH is 88.42g, and SnCl4.5H2The amount of O used was 1.05g, the amount of water used was 27.01g and the amount of HF used was 20 g.
Preparation of example 3
In the present preparation example, reference is made to "Yang X, Wu L, Wang Z, et al. conversion from dihydroxycatalyst to methyl lactate catalyzed by high active Sn-USY at room temperature [ J ]. Catalysis Science & Technology,2016,6(6): 1757-1763" method for preparing Sn-USY molecular sieves, which comprises:
mixing the H-USY molecular sieve with nitric acid, treating at 85 ℃ for 8H, filtering and washing a sample with deionized water, and drying at 120 ℃ for 12H to obtain a solid sample. This solid sample was mixed with tin tetrachloride pentahydrate (SnCl)4.5H2O) for 1 hour to obtain a mixture with a chemical composition of 0.03SnO2：100SiO2The 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, and SnCl4.5H2The amount of O used was 0.6 g.
Preparation of example 4
The preparation example prepares the TS-1 molecular sieve, and the specific preparation method comprises the following steps:
an amount of about 3/4 tetrapropylammonium hydroxide (TPAOH, 20%) solution was added to a Tetraethylorthosilicate (TEOS) solution to obtain a liquid mixture having a pH of about 13, and then the desired amount of n-butyl titanate [ Ti (OBu) ] was added dropwise to the resulting liquid mixture with vigorous stirring4]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 348-2：SiO2:0.36TPA：35H2And O sol, then crystallizing for 3 days at the temperature of 443K, filtering the obtained solid, washing with distilled water, drying for 5 hours at the temperature of 373K, and then roasting for 10 hours at the condition of 823K to obtain a molecular sieve sample. Wherein the amount of TEOS is 42g, the amount of TPAOH is 73g, Ti (OBu)4The amount of (A) was 2g, the amount of anhydrous isopropyl alcohol was 10g, and the amount of water was 68 g.
Preparation of example 5
The preparation method for preparing the TS-2 molecular sieve comprises the following steps:
a certain amount of tetrabutylammonium hydroxide solution (TBAOH, 20%) was mixed with tetraethyl orthosilicate (TEOS), and then to the resulting clear liquid mixture was added dropwise the desired amount of n-butyl titanate [ Ti (OBu) ]with vigorous stirring4]Stirring for 30 minutes to obtain a clear liquid after hydrolysis. Finally, 2 times the amount of distilled water was added and the resulting sol was stirred at 348 ℃ and 353K for 2h to remove the alcohol. The chemical composition of the sol obtained was 0.03TiO2：SiO2:0.2TBA：20H2And 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 TEOS is 42g, TBAOH is 52g, Ti (OBu)4The amount of (A) was 2g, the amount of anhydrous isopropyl alcohol was 10g, and the amount of water was 30 g.
Preparation of example 6
The preparation embodiment for preparing the Ti-Beta molecular sieve comprises the following specific preparation methods:
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 2 h. 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 TiO2：60SiO2:33TEA：400H2O:20H2O2The 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). After the mixture 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 TEOS is used in an amount of 42g, TEAOH is used in an amount of 81g, Ti (OBu)4The dosage of the compound is 1.16g, the dosage of the anhydrous isopropanol is 10g, and the dosage of the hydrogen peroxide is 7.5 g.
Preparation of comparative example 1
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 100: 0.15: 150 of molecular sieve (g) to sulfuric acid (mol) to water (mol), 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) of 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 being 0.10 and the adsorption time being 1 hour 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 2
The preparation method of the tin-loaded titanium silicalite Sn/TS-1 adopted in the preparation comparative example is as follows:
the pentahydrate stannic chloride (SnCl)4.5H2O) and TS-1 molecular sieve (prepared by the method of the comparative preparation example 1) are directly and mechanically mixed and then are roasted for 5 hours at 550 ℃ to obtain a chemical groupTo 0.03TiO2:SiO2:0.03SnO2The molecular sieve of (1). Wherein the dosage of TS-1 is 2g, SnCl4.5H2The amount of O used was 0.76 g.
Examples and comparative examples are provided to illustrate the preparation of lactic acid by catalyzing saccharides using different catalysts.
Example 1
0.15g of the tin-silicon molecular sieve Sn-MFI prepared in preparation example 1 and 0.15g of the titanium-silicon molecular sieve TS-1 prepared in preparation example 4 are weighed out as catalysts and filled in a 100mL polytetrafluoroethylene lining, and then 8g of water and 0.1g of glucose are added in sequence. The polytetrafluoroethylene lining is placed in a stainless steel reaction kettle for sealing and placed in a homogeneous reactor for starting reaction. The reaction temperature is controlled to be about 160 ℃ and the reaction is carried out for 17 hours. The specific reaction results are shown in Table 1.
Comparative example 1
0.3g of the Sn-MFI catalyst of the tin-silicon molecular sieve prepared in preparation example 1 was weighed out and packed in a 100mL polytetrafluoroethylene liner, and 8g of water and 0.1g of glucose were sequentially added. The polytetrafluoroethylene lining is placed in a stainless steel reaction kettle for sealing and placed in a homogeneous reactor for starting reaction. The reaction temperature is controlled to be about 160 ℃ and the reaction is carried out for 17 hours. The specific reaction results are shown in Table 1.
Comparative example 2
0.3g of the titanium silicalite TS-1 catalyst prepared in preparation example 4 was weighed out and loaded into a 100mL polytetrafluoroethylene liner, and then 8g of water and 0.1g of glucose were added in sequence. The polytetrafluoroethylene lining is placed in a stainless steel reaction kettle for sealing and placed in a homogeneous reactor for starting reaction. The reaction temperature is controlled to be about 160 ℃ and the reaction is carried out for 17 hours. The specific reaction results are shown in Table 1.
Comparative example 3
0.3g of the hollow titanium silicalite HTS catalyst prepared in the preparation comparative example 1 is weighed and filled in a 100mL polytetrafluoroethylene lining, and then 8g of water and 0.1g of glucose are sequentially added. The polytetrafluoroethylene lining is placed in a stainless steel reaction kettle for sealing and placed in a homogeneous reactor for starting reaction. The reaction temperature is controlled to be about 160 ℃ and the reaction is carried out for 17 hours. The specific reaction results are shown in Table 1.
Comparative example 4
0.3g of the Sn/TS-1 catalyst of the Sn-loaded titanium silicalite molecular sieve prepared in the preparation comparative example 2 is weighed and filled in a 100mL polytetrafluoroethylene lining, and then 8g of water and 0.1g of glucose are sequentially added. The polytetrafluoroethylene lining is placed in a stainless steel reaction kettle for sealing and placed in a homogeneous reactor for starting reaction. The reaction temperature is controlled to be about 160 ℃ and the reaction is carried out for 17 hours. The specific reaction results are shown in Table 1.
Comparative example 5
The same as example 1 except that: the reaction temperature was 120 ℃ and the reaction time was 8 hours. The specific reaction results are shown in Table 1.
Comparative example 6
The same as example 1 except that: the reaction temperature was 270 ℃ and the reaction time was 55 hours. The specific reaction results are shown in Table 1.
Example 2
0.15g of the Sn-Beta molecular sieve prepared in preparation example 2 and 0.15g of the TS-1 molecular sieve prepared in preparation example 4 are weighed as catalysts and filled in a 100mL polytetrafluoroethylene lining, and then 8g of water and 0.1g of fructose are sequentially added. The polytetrafluoroethylene lining is placed in a stainless steel reaction kettle for sealing and placed in a homogeneous reactor for starting reaction. The reaction temperature is controlled to be about 160 ℃ and the reaction is carried out for 17 hours. The specific reaction results are shown in Table 1.
Example 3
0.15g of the Sn-USY molecular sieve prepared in preparation example 3 and 0.15g of the TS-1 molecular sieve prepared in preparation example 4 are weighed as catalysts and filled in a 100mL polytetrafluoroethylene lining, and then 8g of water and 0.1g of xylose are sequentially added. The polytetrafluoroethylene lining is placed in a stainless steel reaction kettle for sealing and placed in a homogeneous reactor for starting reaction. The reaction temperature is controlled to be about 160 ℃ and the reaction is carried out for 17 hours. The specific reaction results are shown in Table 1.
Example 4
0.15g of the tin-silicon molecular sieve Sn-MFI prepared in preparation example 1 and 0.15g of the titanium-silicon molecular sieve TS-2 prepared in preparation example 5 are weighed out as catalysts and filled in a 100mL polytetrafluoroethylene lining, and then 8g of water and 0.1g of sucrose are added in sequence. The polytetrafluoroethylene lining is placed in a stainless steel reaction kettle for sealing and placed in a homogeneous reactor for starting reaction. The reaction temperature is controlled to be about 160 ℃ and the reaction is carried out for 17 hours. The specific reaction results are shown in Table 1.
Example 5
0.15g of the tin-silicon molecular sieve Sn-MFI prepared in preparation example 1 and 0.15g of the titanium-silicon molecular sieve Ti-Beta prepared in preparation example 6 are weighed out as catalysts and filled in a 100mL polytetrafluoroethylene lining, and then 8g of water and 0.1g of mannose are added in sequence. The polytetrafluoroethylene lining is placed in a stainless steel reaction kettle for sealing and placed in a homogeneous reactor for starting reaction. The reaction temperature is controlled to be about 160 ℃ and the reaction is carried out for 17 hours. The specific reaction results are shown in Table 1.
Example 6
0.5g of the tin-silicon molecular sieve Sn-MFI prepared in preparation example 1 and 0.5g of the titanium-silicon molecular sieve TS-1 prepared in preparation example 4 are weighed out as catalysts and filled in a 100mL polytetrafluoroethylene liner, and then 8g of water and 0.2g of glucose are added in sequence. The polytetrafluoroethylene lining is placed in a stainless steel reaction kettle for sealing and placed in a homogeneous reactor for starting reaction. The reaction temperature is controlled to be about 150 ℃ and the reaction is carried out for 20 hours. The specific reaction results are shown in Table 1.
Example 7
0.01g of the tin-silicon molecular sieve Sn-MFI prepared in preparation example 1 and 0.03g of the titanium-silicon molecular sieve TS-1 prepared in preparation example 4 were weighed out as catalysts and charged in a 100mL polytetrafluoroethylene liner, and 8g of water and 0.2g of glucose were added in this order. The polytetrafluoroethylene lining is placed in a stainless steel reaction kettle for sealing and placed in a homogeneous reactor for starting reaction. The reaction temperature is controlled at about 170 ℃ and the reaction lasts 18 hours. The specific reaction results are shown in Table 1.
Example 8
0.1g of the tin-silicon molecular sieve Sn-MFI prepared in preparation example 1 and 0.1g of the titanium-silicon molecular sieve TS-1 prepared in preparation example 4 are weighed out as catalysts and filled in a 100mL polytetrafluoroethylene liner, and then 8g of water and 0.7g of glucose are added in sequence. The polytetrafluoroethylene lining is placed in a stainless steel reaction kettle for sealing and placed in a homogeneous reactor for starting reaction. The reaction temperature is controlled to be about 150 ℃ and the reaction lasts for 14 hours. The specific reaction results are shown in Table 1.
Example 9
The same as example 1 except that: the molar ratio of sugar to water is 1: 50, the reaction temperature is 150 ℃, the reaction time is 10 hours, the weight ratio of the sugar to the mixture of the titanium silicalite molecular sieve and the tin silicalite molecular sieve is 1:0.1, and the weight ratio of the titanium silicalite molecular sieve to the tin silicalite molecular sieve is 1: 0.1. The specific reaction results are shown in Table 1.
Example 10
The same as example 1 except that: the molar ratio of sugar to water is 1: 1600 at the reaction temperature of 250 ℃ for 50 hours, wherein the weight ratio of the sugar to the mixture of the titanium silicalite molecular sieve and the tin silicalite molecular sieve is 1:6, and the weight ratio of the titanium silicalite molecular sieve to the tin silicalite molecular sieve is 1: 10. 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 mixture of a titanium silicalite molecular sieve and a tin silicalite molecular sieve, and the molar ratio of sugar to water is 1: (50-1600), the reaction temperature is 150-250 ℃, the reaction time is 10-50h, and the weight ratio of the sugar to the mixture of the titanium silicalite molecular sieve and the tin silicalite molecular sieve is 1: (0.1-6), and further preferably the molar ratio of sugar to water is 1: (100-1000), the weight ratio of the sugar to the mixture of the titanium silicalite molecular sieves and the tin silicalite molecular sieves is 1: (0.2-3), the reaction temperature is 155-220 ℃, the reaction time is 12-40h, and the reaction pressure is 0.1-4MPa, which is more favorable for improving the conversion rate of sugar and the yield of lactic acid.
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 Sugar conversion/% Lactic acid selectivity/%)
Example 1 84 68
Example 2 81 64
Example 3 81 66
Example 4 80 65
Example 5 81 61
Example 6 85 63
Example 7 82 65
Example 8 83 64
Example 9 80 60
Example 10 85 60
Comparative example 1 62 45
Comparative example 2 42 40
Comparative example 3 46 31
Comparative example 4 30 16
Comparative example 5 47 35
Comparative example 6 83 35

Claims (10)

1. A method of producing lactic acid, the method comprising:
contacting sugar and water with a catalyst in a reactor and carrying out reaction to obtain a product containing lactic acid; wherein the molar ratio of sugar to water is 1: (50-1600) the reaction temperature is 150-250 ℃, the reaction time is 10-50h, the catalyst contains a mixture of titanium silicalite and tin silicalite, and the weight ratio of sugar to the mixture of titanium silicalite and tin silicalite on a dry basis weight is 1: (0.1-6).
2. The process of claim 1, wherein the tin-silicon molecular sieves are selected from one or more of MFI-type tin-silicon molecular sieves, MEL-type tin-silicon molecular sieves, BEA-type tin-silicon molecular sieves, MWW-type tin-silicon molecular sieves, MOR-type tin-silicon molecular sieves, hexagonal structure tin-silicon molecular sieves, and FAU-type tin-silicon molecular sieves.
3. The process of claim 1, wherein the titanium silicalite molecular sieves are selected from one or more of MFI-type titanium silicalite molecular sieves, MEL-type titanium silicalite molecular sieves, BEA-type titanium silicalite molecular sieves, MWW-type titanium silicalite molecular sieves, MOR-type titanium silicalite molecular sieves, TUN-type titanium silicalite molecular sieves, and hexagonal structure titanium silicalite molecular sieves.
4. The process of claim 1, wherein the tin-silicon molecular sieves are selected from one or more of Sn-MFI molecular sieves, Sn-MEL molecular sieves, Sn-Beta molecular sieves, Sn-MCM-22 molecular sieves, Sn-MOR molecular sieves, Sn-MCM-41 molecular sieves, Sn-SBA-15 molecular sieves, and Sn-USY molecular sieves.
5. The process of claim 1, wherein the titanium silicalite molecular sieves are selected from one or more of TS-1 molecular sieves, TS-2 molecular sieves, Ti-Beta molecular sieves, Ti-MCM-22 molecular sieves, Ti-MOR molecular sieves, Ti-TUN molecular sieves, Ti-MCM-41 molecular sieves, Ti-SBA-15 molecular sieves, and Ti-ZSM-48 molecular sieves.
6. The method of claim 1, wherein the weight ratio of titanium silicalite molecular sieves to tin silicalite molecular sieves in the catalyst is 1: (0.1-10).
7. The process of claim 1, wherein the titanium silicalite molecular sieve has a titania to silica molar ratio of (0.01-10): 100, preferably (0.05-5): 100;
the molar ratio of tin dioxide to silicon dioxide in the tin-silicon molecular sieve is (0.01-10): 100, preferably (0.05-5): 100.
8. The method according to claim 1, wherein the sugar is one or more selected from the group consisting of a pentose, a hexose, and a disaccharide, the pentose is xylose, the hexose is one or more selected from the group consisting of glucose, fructose, and mannose, and the disaccharide is sucrose.
9. The method of claim 1, wherein the molar ratio of sugar to water is 1: (100-1000), the weight ratio of the sugar to the mixture of the titanium silicalite molecular sieves and the tin silicalite molecular sieves is 1: (0.2-3), the reaction temperature is 155-220 ℃, the reaction time is 12-40h, the reaction pressure is 0.1-6MPa, and the reaction pressure is preferably 0.1-4 MPa.
10. 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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Publication number Priority date Publication date Assignee Title
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CN107827727A (en) * 2017-11-09 2018-03-23 中国科学院上海高等研究院 The method that lactic acid is prepared using carbohydrate

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MARTIN SPANGSBERG HOLM等: "Conversion of Sugars to Lactic Acid Derivatives Using Heterogeneous Zeotype Catalysts", 《SCIENCE》 *

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