CN116764673A - Modified molecular sieve catalyst and preparation method and application thereof - Google Patents

Modified molecular sieve catalyst and preparation method and application thereof Download PDF

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Publication number
CN116764673A
CN116764673A CN202310725226.7A CN202310725226A CN116764673A CN 116764673 A CN116764673 A CN 116764673A CN 202310725226 A CN202310725226 A CN 202310725226A CN 116764673 A CN116764673 A CN 116764673A
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molecular sieve
sieve catalyst
modified molecular
hzsm
lactic acid
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章平毅
毛海舫
解锶锶
赵韵
王朝阳
刘吉波
郑翔
靳苗苗
许振民
袁嘉成
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Shanghai Institute of Technology
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    • 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
    • B01J29/40—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively
    • 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
    • B01J29/40—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively
    • B01J29/405—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively 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
    • C07C67/00—Preparation of carboxylic acid esters
    • C07C67/08—Preparation of carboxylic acid esters by reacting carboxylic acids or symmetrical anhydrides with the hydroxy or O-metal group of organic compounds
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C67/00—Preparation of carboxylic acid esters
    • C07C67/48—Separation; Purification; Stabilisation; Use of additives
    • C07C67/52—Separation; Purification; Stabilisation; Use of additives by change in the physical state, e.g. crystallisation
    • C07C67/54—Separation; Purification; Stabilisation; Use of additives by change in the physical state, e.g. crystallisation by distillation
    • 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
    • B01J2229/186—After treatment, characterised by the effect to be obtained to introduce other elements into or onto the molecular sieve itself not in framework positions
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C2601/00—Systems containing only non-condensed rings
    • C07C2601/12—Systems containing only non-condensed rings with a six-membered ring
    • C07C2601/14—The ring being saturated

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Catalysts (AREA)

Abstract

The invention relates to a modified molecular sieve catalyst, a preparation method and application thereof, wherein the catalyst takes an HZSM-5 molecular sieve as a carrier, the active component is zirconium, and the auxiliary agent is at least one metal of titanium, cerium and tin. The catalyst is prepared by adopting a conventional coprecipitation method: firstly, dissolving zirconium metal salt and at least one metal salt of an auxiliary agent in water, adding raw powder HZSM-5 under the condition of stirring, dropwise adding ammonia water, and then sequentially aging, filtering, washing, drying and roasting to obtain a modified molecular sieve catalyst; the catalyst prepared can be prepared by lactic acid-L-menthyl ester. Compared with the prior art, the modified molecular sieve catalyst prepared by the invention can be reused, does not corrode equipment, does not pollute the environment, and is environment-friendly; the method is used for the synthesis process of the lactic acid-L-menthyl ester, has the advantages of simple operation, high reaction speed, high yield and the like, and provides a good industrialized way for producing the lactic acid-L-menthyl ester.

Description

Modified molecular sieve catalyst and preparation method and application thereof
Technical Field
The invention relates to the technical field of fine chemical synthesis, in particular to a modified molecular sieve catalyst and a preparation method and application thereof.
Background
Lactic acid-L-menthyl ester has soft mint fragrance, has tobacco rhyme and cool smell, and has long-term comfortable cool feeling. Physiological coolants widely used in flavors, oral care and cosmetics.
The preparation of the lactic acid-L-menthyl ester generally adopts a conventional direct esterification method, and L-lactic acid and L-menthol are heated and refluxed under the action of an acid catalyst to obtain the product.
CN101287699B employs commonly used acidic catalysts such as sulfuric acid, p-toluene sulfonic acid, acidic ion exchange resins, sodium bisulfate, etc.; water-carrying agents, such as toluene, heptane or other water-carrying agents; l-menthol reacts with lactic acid to obtain Menthyl Lactate (ML), menthyl Lactoyl Lactate (MLL) and menthyl lactoyl lactate (MLLL), wherein the MLL and MLLL are converted into ML by hydrolysis of aqueous solution of alkali (alkali metal hydroxide, alkali metal carbonate), and then the water-carrying agent is recovered and distilled to obtain the pure product of the menthyl lactate.
CN108610257A is prepared by reacting L-menthol with lactic acid to obtain crude menthyl lactate, recovering the water-carrying agent, and recrystallizing or treating by silica gel chromatography to obtain pure L-menthyl lactate.
CN112409182A is dehydrated under negative pressure under the condition of no water carrying agent in vacuum, p-toluenesulfonic acid is adopted as a catalyst L-menthol to react with lactic acid to obtain a crude product of menthyl lactate, lactic acid and menthol are recovered, and acetone is adopted for recrystallization to obtain a pure product.
CN112409179a selects a mixture containing menthyl lactate produced by direct esterification of menthol and lactic acid, adds low-polarity alkane, and stirs and extracts; washing the organic layer with alkaline saturated saline water to neutrality, standing for layering, and evaporating the organic solvent under reduced pressure to obtain extract concentrate; dissolving the concentrate in lower alcohol, then loading into macroporous resin HP-20 chromatographic column, gradient eluting with lower alcohol with different concentrations, mixing menthyl lactate segments, concentrating, and recovering solvent to obtain menthyl lactate crude product; the crude product is dissolved in aqueous solution of isopropanol, filtered, and the supernatant is cooled for crystallization to obtain purified menthyl lactate.
CN103058868A takes excess lactic acid and menthol as raw materials, and directly generates Menthyl Lactate (ML) and Menthyl Lactoyl Lactate (MLL) and menthyl lactoyl lactate (MLLL) under the action of a catalyst. The Menthyl Lactoyl Lactate (MLL) and menthyl lactoyl lactate (MLLL) are converted to Menthyl Lactate (ML) by stirring for several hours with direct addition of buffer solution or saturated solution of acid salt without any other treatment.
As can be seen from the prior disclosures, the catalysts used in the preparation of L-menthyl lactate are: concentrated sulfuric acid, sodium bisulfate, p-toluenesulfonic acid, acidic clay and acidic ion exchange resins. The acidic clay can physically collapse at high temperature, the interlayer solvent is discharged and is adhered, the catalytic activity is lost, and the recycling efficiency is low; ion exchange resins have poor thermal stability and the maximum operating temperature of the acidic resins is 120 ℃. Concentrated sulfuric acid is used, and byproducts are easy to generate due to strong oxidizing property, dehydration property and sulfonation property; the catalyst dissolved in the reaction system brings difficulty to post-treatment, the catalyst cannot be recycled, and a large amount of wastewater is generated to pollute the environment. One method for converting MLL or MLLL into ML adopts aqueous solution saponification reaction of alkali, and the conversion degree is controlled by controlling pH value, so that the defect of difficult control of the conversion degree exists; the other method adopts buffer solution or saturated solution of acid salt to convert MLL or MLL into ML, and has the defects of low efficiency, difficult post-treatment and the like.
Accordingly, there is a need for a modified molecular sieve catalyst that can be used in the synthesis of lactic acid-L-menthyl esters to address the above-described problems.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a modified molecular sieve catalyst, a preparation method and application thereof, wherein the prepared Zr-HZSM-5/M (M=Ti, ce and Sn) modified molecular sieve catalyst has high catalytic efficiency, has better catalytic activity in esterification reaction than an unmodified HZSM-5 molecular sieve, and can be used for synthesizing lactic acid-L-menthyl ester.
The aim of the invention can be achieved by the following technical scheme:
a first object of the present invention is to provide a method for preparing a modified molecular sieve catalyst, the method comprising the steps of: dissolving active metal salt and auxiliary metal salt in water, adding raw powder HZSM-5 under stirring, then dropwise adding ammonia water, adjusting the pH value of the prepared solution, and sequentially carrying out ageing, filtering, washing, drying and roasting to obtain a modified molecular sieve catalyst, wherein the modified molecular sieve catalyst is Zr-HZSM-5/M modified molecular sieve catalyst; wherein M comprises one or more of Ti, ce and Sn; the active metal salt comprises a zirconium salt; the auxiliary metal salt comprises one or more of zirconium salt, titanium salt, cerium salt and tin salt.
Further, the preparation method comprises the following steps: pouring the prepared active metal salt solution with a certain concentration into a container, adding at least one auxiliary metal salt solution under the condition of stirring, adding a certain amount of raw powder HZSM-5 (the active metal salt and the auxiliary metal salt are dissolved in water, adding the raw powder HZSM-5 under the condition of stirring), then dropwise adding ammonia water, regulating the pH value of the prepared solution, and sequentially performing the processes of ageing, filtering, washing, drying and roasting to obtain the modified molecular sieve catalyst.
Further, the Zr-HZSM-5/M modified molecular sieve catalyst takes an HZSM-5 molecular sieve as a carrier, the active component is zirconium, and the auxiliary agent is at least one metal of titanium, cerium and tin.
Further, the Si/Al (silicon to aluminum ratio) in the HZSM-5 molecular sieve is 25;
further, the Zr loading amount in the Zr-HZSM-5/M modified molecular sieve catalyst is 4-8wt%.
Further, in the Zr-HZSM-5/M modified molecular sieve catalyst, when M=Ti, the molar ratio of Ti to Zr is 0.06-0.12.
Further, in the Zr-HZSM-5/M modified molecular sieve catalyst, when M=Ce, the molar ratio of Ce to Zr is 0.12-0.20.
Further preferably, in the Zr-HZSM-5/M modified molecular sieve catalyst, the Ce/Zr molar ratio is 0.16 when m=ce.
Further, in the Zr-HZSM-5/M modified molecular sieve catalyst, when M=Sn, the Sn/Zr molar ratio is 0.10-0.16.
Further, in the Zr-HZSM-5/M modified molecular sieve catalyst, when m=sn, the Sn/Zr molar ratio is 0.12.
Further, the zirconium salt is selected from one or more of zirconyl nitrate or zirconium oxychloride octahydrate.
Further, the titanium salt includes titanium tetrachloride.
Further, the cerium salt includes cerium nitrate.
Further, the tin salt includes tin tetrachloride.
Further, the aging time is 20-24 hours.
Further, the drying temperature is 110-120 ℃.
Further, the roasting temperature is 500-650 ℃, and the roasting time is 4-5h.
Further, the firing temperature was 600 ℃.
Further, the concentration of the ammonia water is 10-15%, and the pH is 9-10.
A second object of the present invention is to provide a modified molecular sieve catalyst which is obtained by the above-described preparation method.
A third object of the present invention is to provide the use of a modified molecular sieve catalyst for use in a process for the preparation of lactic acid-L-menthyl ester.
The application principle is as follows: the oxide solid acid has good thermal stability, active components are not easy to run off, and the oxide solid acid can be used for high temperature and liquid phase reaction. HZSM-5 molecular sieve is used as a solid acid, the surface acidity of which is the key of the liquid phase esterification reaction of the catalyst, and the esterification reaction can be carried out on the B acid center or the L acid center. The HZSM-5 molecular sieve after the modification of the active Zr increases the stronger B acid amount on the catalyst, and simultaneously obviously increases the L acid amount, along with the increase of the zirconium loading amount, the B acid amount is not obviously increased, but the trend of the increase of the L acid amount is obvious, but after the zirconium loading amount is increased to a certain amount, the specific surface area of the molecular sieve is reduced, and the ZrO 2 Agglomeration occurs and causes damage to the overall structure of the molecular sieve to a certain extent. Tetragonal ZrO during calcination 2 Is easily converted into monoclinic form, and the monoclinic form ZrO 2 Can not form solid superacid, and the addition of the auxiliary agent M improves the tetragonal ZrO 2 The transformation temperature to monoclinic form is changed because ZrO is obtained when the calcination temperature is low 2 The tetragonal crystal forms necessary for the formation of solid superacids are not sufficient; as the content of M increases, the number of acid centers formed on the solid surface increases gradually, when MO X The content is increased to ZrO 2 MO at the surface monolayer dispersion threshold X Will self-form into one phase, hinder ZrO 2 The transformation from tetragonal crystal form to monoclinic crystal form makes the surface acidity of the catalyst reach the strongest, and the MO is continuously increased X In this case, the catalyst surface acidity is rather reduced, possibly due to excessive MO X Attached to ZrO 2 The surface may hinder the formation of acid centres. In a word, the supported oxide solid acid and the acid center on the surface of the HZSM-5 molecular sieve jointly act, so that the catalytic performance of the modified molecular sieve (modified molecular sieve catalyst) is improved.
Further, the modified molecular sieve catalyst is used in the preparation process of lactic acid-L-menthyl ester, and comprises the following steps:
1) Adding a certain amount of lactic acid, menthol, a water-carrying agent and the modified molecular sieve catalyst into a reactor provided with an oil-water separator, heating, refluxing and dehydrating until the water yield reaches a theoretical value to generate menthyl lactate (ML, monoester) and menthyl lactoyl lactate (MLL, diester), wherein the menthyl lactate is monoester, the menthyl lactoyl lactate is diester, filtering to separate the modified molecular sieve catalyst, recovering a solvent from the filtrate, rectifying and purifying to separate raw menthol and product monoester, and the non-distilled residues are part of monoester and byproduct diester, and using the non-distilled residues for saponification;
2) And (3) saponification, namely adding a solvent and an aqueous alkali solution into residues which are not distilled in the step (I) to carry out hydrolysis, controlling the concentration and the temperature of the alkali in the hydrolysis reaction, so that the diester is basically converted into monoester, less menthol is hydrolyzed from the monoester, and after saponification, recovering the solvent and distilling to obtain the monoester product.
Further, in the step 1), the lactic acid is one or more of D-lactic acid, L-lactic acid and D, L-lactic acid.
Further preferably, in step 1), the lactic acid is L-lactic acid
Further, in step 1), the menthol is one or more of D-menthol, L-menthol and D, L-menthol.
Further preferably, in step 1), the menthol is L-menthol.
Further, in step 1), the molar ratio of the lactic acid to the menthol is 1.0-1.5:1.0.
Further preferably, in step 1), the molar ratio of lactic acid to menthol is 1.2:1.0
Further, in step 1), the total weight ratio of the modified molecular sieve catalyst to the feedstock (including lactic acid and menthol) (the weight of the feedstock is the weight of lactic acid and menthol) is 1.0-4.0:100.0.
Further preferably, in step 1), the modified molecular sieve catalyst to feedstock total weight ratio is 2.0:100.0.
Further, in the step 1), the water-carrying agent is one or more of toluene, benzene, cyclohexane, heptane and the like which can be azeotroped with water.
Further, in the step 1), the modified molecular sieve catalyst separated by filtration may be reused, and after the activity is lowered, the modified molecular sieve catalyst separated by filtration may be recovered and the activity is recovered by calcination (calcination temperature 600 ℃ for 4 to 5 hours).
Further, in the step 2), the alkali is one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate and the like.
Further preferably, in step 2), the base is sodium hydroxide or potassium hydroxide.
Further, in the step 2), the concentration of the alkali for hydrolysis in the saponification reaction is 10wt% to 60wt%.
Further preferably, in step 2), the concentration of the base used for hydrolysis in the saponification reaction is 30wt% to 40wt%.
Further, in step 2), the molar ratio of the base to the diester is 1.0-1.5:1.0.
Further, in step 2), the hydrolysis temperature is 0-35 ℃.
Further, in step 2), the hydrolysis temperature is 10-30 ℃.
Compared with the prior art, the invention has the following beneficial effects:
1) The modified molecular sieve catalyst provided by the invention is a Zr-HZSM-5/M (M=Ti, ce and Sn) modified molecular sieve catalyst, has high catalytic efficiency, can be reused, does not corrode equipment, does not pollute the environment, and is environment-friendly.
2) The modified molecular sieve catalyst provided by the invention is used for preparing lactic acid-L-menthyl ester, and Zr-HZSM-5/M (M=Ti, ce and Sn) modified molecular sieve catalyst is adopted in esterification, and active component ZrO in the catalyst 2 The amount of B acid and L acid in the catalyst can be increased, and the auxiliary MOx can block ZrO 2 The surface acidity of the catalyst is obtained by converting tetragonal crystal form into monoclinic crystal formReinforcing; the catalytic activity of the modified Zr-HZSM-5/M in the esterification reaction is better than that of an unmodified HZSM-5 molecular sieve, and the catalyst is obviously better than that of concentrated sulfuric acid, sodium bisulfate, p-toluenesulfonic acid, acidic clay, acidic ion exchange resin and the like.
3) The modified molecular sieve catalyst provided by the invention is used for the preparation process of lactic acid-L-menthyl ester, and simultaneously improves the prior process in esterification, diester is separated out by rectification, and the diester is converted into monoester by controlling the concentration of alkali in saponification, so that the diester is more easily converted into monoester.
4) The invention has simple operation, simple process route and little environmental pollution.
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the present invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications could be made by those skilled in the art without departing from the inventive concept. These are all within the scope of the present invention.
In the technical scheme, the characteristics of preparation means, materials, structures or composition ratios and the like which are not explicitly described are regarded as common technical characteristics disclosed in the prior art.
The technical scheme provides a modified molecular sieve catalyst, a preparation method and application thereof, wherein the catalyst takes an HZSM-5 molecular sieve as a carrier, the active component is zirconium, and the auxiliary agent is at least one metal of titanium, cerium and tin. The catalyst is prepared by adopting a conventional coprecipitation method: firstly, dissolving zirconium metal salt and at least one metal salt of an auxiliary agent in water, adding raw powder HZSM-5 under the condition of stirring, dropwise adding ammonia water, and then sequentially aging, filtering, washing, drying and roasting to obtain a modified molecular sieve catalyst; the catalyst prepared can be prepared by lactic acid-L-menthyl ester.
Chromatographic column: SE×54, 30m×0.25mm×0.50um.
Analysis conditions: injector temperature: 250 ℃, column box temperature: 180 ℃, detector temperature: 280 ℃.
In the following examples, the starting materials used were all commercially available.
In order to compare the efficiency of different batches of catalysts, the optimal catalyst reaction time (the reaction time is that the water yield basically reaches the theoretical value) is taken as the reaction time of different batches (theoretically, the theoretical value can be reached by prolonging the reaction time).
Example 1
The embodiment provides a preparation method of a modified molecular sieve catalyst, which comprises the following steps:
dissolving 10.16g of zirconyl nitrate (or zirconium oxide octahydrate with the same zirconium content as required) and 0.84g of titanium tetrachloride in 70.0-80.0g of distilled water to obtain a mixed water solution of zirconyl nitrate and titanium tetrachloride, adding 100.0g of raw powder HZSM-5 under stirring, then dropwise adding 10-15% ammonia water to adjust the pH value to 9-10 for precipitation, aging for 20-24h, filtering, and washing a filter cake with distilled water until NO exists 3 - 、Cl - Drying for 4-5h at 110-120 ℃, and roasting for 4-5h at 600 ℃ to obtain the catalyst 4% Zr-HZSM-5/Ti (Ti/Zr=0.10), wherein 4% Zr is the loading of zirconium, and Ti/Zr=0.10 is the molar ratio of titanium to zirconium.
The molar ratio of titanium to zirconium is 0.10, the mass ratio of zirconyl nitrate to raw powder HZSM-5 is changed, and the rest conditions and the preparation process are the same as the above (the preparation process of 4% Zr-HZSM-5/Ti (Ti/Zr=0.10), and the catalysts are respectively prepared: 5% Zr-HZSM-5/Ti (Ti/zr=0.10), 6% Zr-HZSM-5/Ti (Ti/zr=0.10), 7% Zr-HZSM-5/Ti (Ti/zr=0.10), 8% Zr-HZSM-5/Ti (Ti/zr=0.10).
Zirconium loading is 6%, the molar ratio of titanium to zirconium is changed, and the rest conditions and the preparation process are the same as the above (preparation process of 4% Zr-HZSM-5/Ti (Ti/zr=0.10)), and the catalysts are respectively prepared: 6% Zr-HZSM-5/Ti (Ti/zr=0.06), 6% Zr-HZSM-5/Ti (Ti/zr=0.08), 6% Zr-HZSM-5/Ti (Ti/zr=0.12).
Example 2
The embodiment provides a preparation method of a modified molecular sieve catalyst, which comprises the following steps:
15.23g of zirconyl nitrate (optionally replaced by octawater of the same zirconium content)Zirconium oxychloride) and 2.06g of tin tetrachloride are dissolved in 50.0-60.0g of distilled water to obtain mixed aqueous solution of zirconium oxynitrate and tin tetrachloride, 100.0g of raw powder HZSM-5 is added under stirring, then 10-15% ammonia water is added dropwise to adjust the pH value to 9-10 for precipitation, aging is carried out for 20-24h, filtration is carried out, and filter cakes are washed by distilled water until NO exists 3 - 、Cl - Drying for 4-5h at 110-120 ℃, and roasting for 4-5h at 600 ℃ to obtain the catalyst 6% Zr-HZSM-5/Sn (Sn/Zr=0.12, wherein 6% Zr is the loading of zirconium, and Sn/Zr=0.12 is the molar ratio of tin to zirconium).
Example 3
Dissolving 15.23g of zirconyl nitrate (or zirconium oxide octahydrate with the same zirconium content as required) and 4.09g of cerium tetranitrate in 50.0-60.0g of distilled water to obtain a mixed aqueous solution of zirconyl nitrate and cerium tetranitrate, adding 100.0g of raw powder HZSM-5 under stirring, then dropwise adding 10-15% ammonia water to adjust the pH value to 9-10 for precipitation, aging for 20-24h, filtering, and washing a filter cake with distilled water until NO exists 3 - 、Cl - Drying for 4-5h at 110-120 ℃, and roasting for 4-5h at 600 ℃ to obtain the catalyst 6% Zr-HZSM-5/Ce (Ce/Zr=0.16, wherein 6% Zr is the loading of zirconium, and Ce/Zr=0.16 is the molar ratio of cerium to zirconium).
Application example 1
Adding L-lactic acid (85.0%) and L-menthol in a molar ratio of 1.2:1.0 into a reactor provided with a stirrer, a thermometer and an oil-water separator, adding the catalyst prepared in the above example, wherein the total weight ratio of the catalyst to the raw materials is 2.0:100.0, adding a proper water-carrying agent (toluene, cyclohexane and the like, and the total weight ratio of the weight to the raw materials is 1.0-1.2:1.0), heating, refluxing and dehydrating, reacting for 5.0h, stopping the reaction, cooling to room temperature and performing gas phase analysis.
Application example 1 under different conditions the procedure is as above and the results are shown in Table 1. As can be seen from table 1, the modified molecular sieve catalyst is superior to the non-catalyst or non-modified HZSM-5 molecular sieve catalyst in terms of reaction effect, with the best catalyst being 6% Zr-HZSM-5/Ti (Ti/zr=0.10).
Table 1 effects of different catalysts of example 1 on the reaction were applied.
Catalyst Menthol (%) Monoester (%) Diester (%)
No catalyst 85.6 11.7 2.5
HZSM-5 24.8 56.1 18.7
4％Zr-HZSM-5/Ti(Ti/Zr＝0.10) 13.6 64.3 21.6
5％Zr-HZSM-5/Ti(Ti/Zr＝0.10) 11.6 65.6 22.3
6％Zr-HZSM-5/Ti(Ti/Zr＝0.10) 9.5 67.3 22.7
7％Zr-HZSM-5/Ti(Ti/Zr＝0.10) 9.6 67.2 22.7
8％Zr-HZSM-5/Ti(Ti/Zr＝0.10) 9.9 67.0 22.6
6％Zr-HZSM-5/Ti(Ti/Zr＝0.06) 12.0 65.7 21.8
6％Zr-HZSM-5/Ti(Ti/Zr＝0.08) 10.2 66.8 22.5
6％Zr-HZSM-5/Ti(Ti/Zr＝0.12) 9.8 67.1 22.6
6％Zr-HZSM-5/Sn(Sn/Zr＝0.12) 10.0 66.9 22.6
6％Zr-HZSM-5/Ce(Ce/Zr＝0.16) 10.2 66.7 22.6
6％Zr-HZSM-5/Ti(Ti/Zr＝0.10) a 11.0 66.3 22.2
6％Zr-HZSM-5/Ti(Ti/Zr＝0.10) b 9.5 67.3 22.7
a. The catalyst is reused for the fifth time, b. the catalyst is calcined again after the activity is reduced
Application example 2
A2000 ml round-bottom three-necked flask equipped with a stirrer, a thermometer and an oil-water analyzer was charged with 312.0 (2.0 mol) g of L-menthol, 254.1 (85.0%, 2.4 mol) g of L-lactic acid, 11.3g of the 6% Zr-HZSM-5/Ti (Ti/Zr=0.10) catalyst prepared in the above example and 800ml of cyclohexane, dehydrated by heating under reflux until the oil-water separator was free of water (about 73.0 ml), reacted for 5.0 hours, the reaction was stopped, the catalyst was separated by filtration, and the filtrate was washed with water to neutrality. Recovering solvent at normal pressure, and rectifying the residual crude product of lactic acid-L-menthyl ester under reduced pressure to obtain lactic acid-L-menthyl ester product, wherein the rectification parameters are shown in Table 2 and Table 3. As can be seen from Table 3, menthol, monoester and diester can be effectively purified by adopting a vacuum rectification method, menthol can be used as a raw material for continuous reaction, and diester can be converted into monoester by hydrolysis.
Table 2 example 2 rectification parameters.
Table 3 the rectification results of example 2 were applied.
Menthol (%) Monoester (%) Diester (%) Weight (g)
After the reaction 9.5 67.3 22.7
Fraction one 99.45 0.45 23.20
Fraction two 38.20 61.70 17.25
Fraction III 99.50 0.40 223.10
Fraction IV 65.60 34.30 116.23
In the bottle 1.50 98.40 98.49
Fraction one, 23.20g, contains 99.45% menthol and 0.45% monoester; the other fractions are similar.
Application example 3
127.8g (98.4% of diester content (0.42 mol) and 1.50% of monoester content) of the residue (in the bottle) obtained by the rectification in application example 2 was charged into a 500ml three-necked flask equipped with a thermometer, a stirrer and a constant pressure dropping funnel, and dissolved in 100ml of cyclohexane, 61.6g (0.46 mol) of 30% aqueous sodium hydroxide solution was then added dropwise thereto, and the mixture was stirred continuously for about 1 hour after the completion of the addition, the hydrolysis reaction was carried out at about 20℃and the gas phase tracing reaction was carried out, whereby menthol content was 1.5%, monoester content was 97.7% and diester content was 0.6%. Stopping the reaction, separating out the water layer, washing with water, recovering the solvent, and rectifying to obtain 90.5g (99.7%) of the product (monoester).
Application example 4
The raw materials are obtained from residues (in a bottle) after rectification in application example 2, proper solvents (solvents such as toluene and cyclohexane) are added for dissolution, then 30-40% alkaline water solution (NaOH or KOH, the molar ratio of alkali to diester is 1.0-1.5:1.0) is added dropwise, stirring is continued after the addition for about 1 hour, the saponification reaction (hydrolysis reaction) temperature is controlled to be 10-30 ℃, and gas phase tracking reaction (preferably the reaction temperature is about 20 ℃) is controlled, so that diester is basically converted into monoester, and menthol is seldom hydrolyzed from monoester. After saponification is finished, separating a water layer, washing with water, recovering a solvent, and rectifying to obtain a product.
Application example 4 under different conditions the procedure is as above and the results are shown in Table 4. As can be seen from Table 4, in the hydrolysis of the diester, the amount of the base used has an effect on the hydrolysis, the hydrolysis of the diester is incomplete with a small amount of the base used, and the amount of the base used is such that the diester is substantially converted to the monoester, but the conversion of the monoester to menthol is increased, and the molar ratio of the base to the diester is preferably 1.1:1.0.
Table 4 the percentages of menthol, monoester, diester (effect of base amount on hydrolyzed diester) in the products obtained under the different conditions of application example 3.
Molar ratio of base/diester Menthol (%) Monoester (%) Diester (%)
Raw materials 0.0 1.5 98.4
1.0:1.0 1.50 93.60 4.80
1.05:1.0 1.50 96.20 2.20
1.1:1.0 1.60 97.7 0.60
1.15:1.0 2.00 97.5 0.4
1.2:1.0 2.80 96.9 0.2
The previous description of the embodiments is provided to facilitate a person of ordinary skill in the art in order to make and use the present invention. It will be apparent to those skilled in the art that various modifications can be readily made to these embodiments and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above-described embodiments, and those skilled in the art, based on the present disclosure, should make improvements and modifications without departing from the scope of the present invention.

Claims (10)

1. A method of preparing a modified molecular sieve catalyst, the method comprising the steps of:
dissolving active metal salt and auxiliary metal salt in water, adding raw powder HZSM-5 under stirring, then dropwise adding ammonia water, adjusting the pH value of the prepared solution, and sequentially carrying out ageing, filtering, washing, drying and roasting to obtain a modified molecular sieve catalyst, wherein the modified molecular sieve catalyst is Zr-HZSM-5/M modified molecular sieve catalyst;
wherein M comprises one or more of Ti, ce and Sn;
the active metal salt comprises a zirconium salt;
the auxiliary metal salt comprises one or more of zirconium salt, titanium salt, cerium salt and tin salt.
2. The method for preparing a modified molecular sieve catalyst according to claim 1, wherein the Zr-HZSM-5/M modified molecular sieve catalyst uses HZSM-5 molecular sieve as a carrier, the active component is zirconium, and the auxiliary agent is at least one metal of titanium, cerium and tin;
the Si/Al in the HZSM-5 molecular sieve is 25;
zr load in the Zr-HZSM-5/M modified molecular sieve catalyst is 4-8wt%;
in the Zr-HZSM-5/M modified molecular sieve catalyst, when M=Ti, the molar ratio of Ti to Zr is 0.06-0.12;
in the Zr-HZSM-5/M modified molecular sieve catalyst, when M=Ce, the molar ratio of Ce to Zr is 0.12-0.20;
in the Zr-HZSM-5/M modified molecular sieve catalyst, when M=Sn, the Sn/Zr molar ratio is 0.10-0.16;
the zirconium salt is selected from one or more of zirconyl nitrate or zirconium oxychloride octahydrate;
the titanium salt comprises titanium tetrachloride;
the cerium salt includes cerium nitrate;
the tin salt includes tin tetrachloride.
3. The method for preparing a modified molecular sieve catalyst of claim 1, wherein the aging time is from 20 to 24 hours;
the drying temperature is 110-120 ℃;
the roasting temperature is 500-650 ℃ and the roasting time is 4-5h.
4. The method for preparing a modified molecular sieve catalyst according to claim 1, wherein the concentration of ammonia is 10-15% and the pH is 9-10.
5. A modified molecular sieve catalyst obtainable by the process of any of claims 1-4.
6. Use of a modified molecular sieve catalyst obtained by the method of any of claims 1-4, wherein the modified molecular sieve catalyst is used in a process for the preparation of lactic acid-L-menthyl ester.
7. The use of a modified molecular sieve catalyst in accordance with claim 6, wherein said modified molecular sieve catalyst is used in a process for the preparation of lactic acid-L-menthyl ester, comprising the steps of:
1) Adding lactic acid, menthol, a water-carrying agent and the modified molecular sieve catalyst into a reactor provided with an oil-water separator, heating, refluxing and dehydrating to generate menthyl lactate and menthyl lactoyl lactate, wherein the menthyl lactate is monoester, the menthyl lactoyl lactate is diester, filtering to separate the modified molecular sieve catalyst, recovering a solvent from filtrate, rectifying and purifying to separate raw menthol and product monoester, and using non-distilled residues which are partial monoester and byproduct diester for saponification;
2) And (3) saponification, namely adding a solvent and an aqueous alkali solution into residues which are not distilled out in the step (I) to carry out hydrolysis, controlling the concentration and the temperature of alkali in the hydrolysis reaction, converting diester into monoester, and obtaining the product monoester through solvent recovery and distillation after saponification.
8. The use of a modified molecular sieve catalyst according to claim 7, wherein in step 1) the lactic acid is one or more of D-lactic acid, L-lactic acid, D, L-lactic acid;
in the step 1), the menthol is one or more of D-menthol, L-menthol and D, L-menthol;
in the step 1), the molar ratio of the lactic acid to the menthol is 1.0-1.5:1.0;
in the step 1), the total weight ratio of the modified molecular sieve catalyst to the raw materials is 1.0-4.0:100.0;
the raw materials comprise lactic acid and menthol;
in the step 1), the water carrying agent is one or more of toluene, benzene, cyclohexane and heptane.
9. Use of a modified molecular sieve catalyst according to claim 7, characterized in that in step 1) the modified molecular sieve catalyst separated by filtration is recovered and regenerated by calcination.
10. The use of a modified molecular sieve catalyst according to claim 7, wherein in step 2) the base is one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate;
in the step 2), the concentration of the alkali used for hydrolysis in the saponification reaction is 10-60 wt%;
in step 2), the molar ratio of the alkali to the diester is 1.0-1.5:1.0;
in the step 2), the hydrolysis temperature is 0-35 ℃.
CN202310725226.7A 2023-06-19 2023-06-19 Modified molecular sieve catalyst and preparation method and application thereof Pending CN116764673A (en)

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