CN109438201A - A method of preparing methacrolein - Google Patents
A method of preparing methacrolein Download PDFInfo
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- CN109438201A CN109438201A CN201811495101.5A CN201811495101A CN109438201A CN 109438201 A CN109438201 A CN 109438201A CN 201811495101 A CN201811495101 A CN 201811495101A CN 109438201 A CN109438201 A CN 109438201A
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- reaction
- methacrolein
- nano
- propionic aldehyde
- pickering emulsion
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- 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
- C07C45/45—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by condensation
-
- 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
- B01J31/00—Catalysts comprising hydrides, coordination complexes or organic compounds
- B01J31/02—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides
- B01J31/0277—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides comprising ionic liquids, as components in catalyst systems or catalysts per se, the ionic liquid compounds being used in the molten state at the respective reaction temperature
- B01J31/0278—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides comprising ionic liquids, as components in catalyst systems or catalysts per se, the ionic liquid compounds being used in the molten state at the respective reaction temperature containing nitrogen as cationic centre
- B01J31/0279—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides comprising ionic liquids, as components in catalyst systems or catalysts per se, the ionic liquid compounds being used in the molten state at the respective reaction temperature containing nitrogen as cationic centre the cationic portion being acyclic or nitrogen being a substituent on a ring
-
- 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
- B01J31/00—Catalysts comprising hydrides, coordination complexes or organic compounds
- B01J31/26—Catalysts comprising hydrides, coordination complexes or organic compounds containing in addition, inorganic metal compounds not provided for in groups B01J31/02 - B01J31/24
-
- 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
- B01J2231/00—Catalytic reactions performed with catalysts classified in B01J31/00
- B01J2231/30—Addition reactions at carbon centres, i.e. to either C-C or C-X multiple bonds
- B01J2231/34—Other additions, e.g. Monsanto-type carbonylations, addition to 1,2-C=X or 1,2-C-X triplebonds, additions to 1,4-C=C-C=X or 1,4-C=-C-X triple bonds with X, e.g. O, S, NH/N
- B01J2231/341—1,2-additions, e.g. aldol or Knoevenagel condensations
- B01J2231/342—Aldol type reactions, i.e. nucleophilic addition of C-H acidic compounds, their R3Si- or metal complex analogues, to aldehydes or ketones
Abstract
The present invention relates to a kind of methods for preparing methacrolein, catalyst of the method using Pickering emulsion as catalysis formaldehyde and propionic aldehyde reaction preparation methacrolein, and reaction process carries out in fixed bed reactors, it is separated to realize product in preparation process with the real-time of catalyst activity component, realize the continuous operation of preparation process, and the catalyst using Pickering emulsion as catalysis formaldehyde and propionic aldehyde reaction preparation methacrolein, increase the contact area of mobile phase reactant Yu aqueous catalysis active component, so that the average conversion of catalysis propionic aldehyde conversion reaches as high as 100%, the yield of methacrolein reaches as high as 90%.
Description
Technical field
The present invention relates to aldol condensation catalytic fields, further to a kind of method for preparing methacrolein.
Background technique
Methacrolein is also known as methacrolein, has active conjugated double bond, can be used for synthetic copolymer, resin and thermoplasticity
Plastics, it can also be used to produce the fine chemical products such as methacrylic acid, methyl methacrylate, butadiene morpholine.Currently, methyl-prop
The industrial production of olefine aldehydr has multiple, is divided into isobutylene oxidation method, alcohol oxidizing process, formaldehyde and propionic aldehyde condensation method according to raw material.
Wherein, formaldehyde and propionic aldehyde condensation method because raw material it is cheap and easy to get, reaction condition is mild, has broad application prospects.
There are two types of reaction path, direct adol reaction and Mannich reactions for formaldehyde and propionic aldehyde condensation preparation methacrolein.
The catalyst of direct adol reaction generally selects NaOH, KOH or triethylamine, propionic aldehyde high conversion rate, but methacrolein selectivity
It is low, there is a large amount of 2- methyl-2-pentenal serving to generate in product.Using the ammonium salt at least containing a hydrogen as catalyst, pass through
Mannich reaction can effectively reduce propionic aldehyde autohemagglutination, improve methacrolein selectivity.
CN104311403A discloses a kind of formaldehyde organic solution and propionic aldehyde and carries out condensation generation under ionic liquid effect
The method of methacrolein, feed liquid need to isolate methacrolein by rectifying after reaction, and dewatered ionic liquid circulation makes
With, there is a problem that can not operating continuously in this scheme the method preparation process, catalyst utilization it is low.
CN104557490A discloses a kind of paraformaldehyde and propionic aldehyde the synthesizing methyl methacrylaldehyde under morpholine hydrochloride effect
Technique, product through distillation and stratification obtain methacrolein, there is preparation process to operate continuously for this scheme, need
The lock out operation for carrying out active component and product, increases the cost of production.
CN102659542A discloses a kind of side with ionic liquid-catalyzed formaldehyde and propionic aldehyde condensation preparation methacrolein
Method, method includes the following steps: water content is 1-60% in reaction system, and formaldehyde and propionic aldehyde exist under ionic liquid-catalyzed
0.1-180min is reacted at 0-90 DEG C, methacrolein is prepared, this scheme the method is interval there is preparation process
Operation, preparation process is complicated, higher cost.
Although above-mentioned document provide it is some preparation methacrolein methods, either direct adol reaction and
Mannich reaction, preparation process is intermittent process, and liquid-phase system needs high-speed stirred to increase reactant and urge in reaction
The contact area of agent needs certain means to separate product with catalyst after reaction, operating procedure is complicated and catalyst utilizes
Rate is low, therefore the preparation method for developing a kind of methacrolein that can be operated continuously still is of great significance.
Summary of the invention
The purpose of the present invention is to provide a kind of methods for preparing methacrolein, and the method is using Pickering cream
Shape liquid as catalysis formaldehyde and propionic aldehyde reaction preparation methacrolein catalyst, and reaction process in fixed bed reactors into
Row separates with the real-time of catalyst activity component to realize product in preparation process, realizes the serialization of preparation process
Operation, and the catalyst using Pickering emulsion as catalysis formaldehyde and propionic aldehyde reaction preparation methacrolein, increase
The contact area of mobile phase reactant and aqueous catalysis active component, so that the average conversion highest of catalysis propionic aldehyde conversion
Up to 100%, the yield of methacrolein reaches as high as 90%.
To achieve this purpose, the present invention adopts the following technical scheme:
The present invention provides a kind of method for preparing methacrolein, the method uses the conduct of Pickering emulsion
It is catalyzed the catalyst of formaldehyde and propionic aldehyde reaction preparation methacrolein, and the preparation process of the method is in fixed bed reactors
It carries out.
Catalysis of the present invention using Pickering emulsion as catalysis formaldehyde and propionic aldehyde reaction preparation methacrolein
Agent, and the preparation process of the method carries out in fixed bed reactors, the solid particle packet in the Pickering emulsion
Water phase is wrapped up in, oily phase is wrapped up on the outside of solid particle, and the Pickering emulsion is placed in fixed bed reactors, thus
So that during the preparation process, the catalytic active component of water phase is separated with the real-time of reaction product, the efficiency of preparation process is improved,
Realize the continuous operation of preparation process.
Preferably, the Pickering emulsion includes the Nano-meter SiO_2 of surface modification2, ionic liquid aqueous solution and organic
Solvent.
Pickering emulsion is placed in fixed bed reactors by the method for the invention, the Pickering emulsion
Nano-meter SiO_2 including surface modification2, ionic liquid aqueous solution and organic solvent, can be formed in the solution after the above components are mixed
The structure of Water-In-Oil；The structure includes the Nano-meter SiO_2 of surface modification2As solid emulsifier, it is water-soluble to wrap up ionic liquid
The water phase that liquid is constituted, the oily phase that outside package organic solvent is formed play catalytic action in preparation process of the present invention
Active component is ionic liquid aqueous solution, and Pickering emulsion is placed in fixed bed reactors, during the preparation process, instead
It answers material by emulsion bed, is contacted with the catalytic active component of water phase, after reaction generates product, the water for reacting generation is stayed in
In water phase, methacrolein then leaves Pickering emulsion, to realize the real-time of reaction product and catalytic active component
Separation, and it is found through experiment that do not find the phenomenon that demulsification and active constituent are lost, therefore this hair in the 72h that preparation process starts
The bright preparation method can be operated continuously.
Preferably, it the described method comprises the following steps:
(1) preparation of Pickering emulsion；
(2) the Pickering emulsion for obtaining step (1) is added in fixed bed reactors, is passed through comprising formaldehyde and third
The reaction mass reaction preparation methacrolein of aldehyde.
Pickering emulsion is placed in fixed bed reactors by the method for preparation methacrolein of the present invention, when
When mobile phase containing reaction mass passes through fixed bed reactors, formaldehyde and propionic aldehyde enter in water phase to be contacted instead with active component
It answers, the product of generation enters oily phase, fixed bed reactors is left with mobile phase later, it is thus achieved that the serialization of preparation process
Operation, increases the active component utilization rate of catalyst.
Solvent in reaction mass of the present invention is for dissolving formaldehyde and propionic aldehyde.
Preferably, the solvent in the reaction mass in hexamethylene, normal octane or toluene any one or at least
Two kinds of mixture, the mixture illustratively include the mixing of the mixture, toluene and hexamethylene of hexamethylene and normal octane
Object or the mixture of normal octane and toluene etc..
Preferably, Pickering emulsion described in step (1) preparation the following steps are included:
(a) Nano-meter SiO_22Surface modification；
(b) Nano-meter SiO_2 for the surface modification for obtaining step (a)2It is successively mixed with organic solvent and ionic liquid aqueous solution
Conjunction obtains Pickering emulsion.
The method of the invention is to Nano-meter SiO_22It is surface modified, it is successively water-soluble with organic solvent and ionic liquid later
Liquid is mixed to get Pickering emulsion, to Nano-meter SiO_22It is surface modified, is conducive to what raising was prepared
The stability of Pickering emulsion, to prevent the generation and catalysis of demulsifying phenomenon during preparing methacrolein
The loss of active constituent.
Pickering emulsion of the present invention, the SiO of surface modification2Can high degree of dispersion two it is alternate formed it is high-strength
Water phase containing catalytic active component is encapsulated in the emulsion droplet of Pickering emulsion by the interfacial film of degree, to realize continuous
Change operation.
Preferably, step (a) Nano-meter SiO_22Surface modification include under nitrogen protection, to Nano-meter SiO_22In successively
Toluene, coating material and organic amine is added, later return stirring, after solid-liquor separation, washing is dried to obtain receiving for surface modification
Rice SiO2。
Preferably, the temperature of the return stirring is 60-80 DEG C, such as 60 DEG C, 65 DEG C, 70 DEG C or 80 DEG C etc..
Preferably, the time of the return stirring is 4-6h, such as 4h, 4.5h, 5h, 5.5h or 6h etc..
Preferably, the temperature of the drying is 100-120 DEG C, such as 100 DEG C, 105 DEG C, 110 DEG C, 115 DEG C or 120 DEG C
Deng.
Preferably, the Nano-meter SiO_22Partial size be 7-500nm, such as 7-40nm, 50nm, 100nm, 150nm, 200nm,
250nm, 300nm, 350nm, 400nm, 450nm or 500nm etc..
Preferably, the coating material includes methyltrimethoxysilane, vinyltrimethoxysilane, propyl front three
In oxysilane, trimethoxysilane or phenyltrimethoxysila,e any one or at least two mixture,
The mixture illustratively includes the mixture of methyltrimethoxysilane and vinyltrimethoxysilane, propyl trimethoxy
Base silane and the mixture or phenyltrimethoxysila,e of trimethoxysilane, methyltrimethoxysilane and vinyl
The mixture etc. of trimethoxy silane.
Preferably, the mole and Nano-meter SiO_2 of the coating material2Mass ratio be 1-4mmol/g, such as 1mmol/
G, 1.5mmol/g, 2mmol/g, 2.5mmol/g, 3mmol/g, 3.5mmol/g or 4mmol/g etc..
Preferably, the organic amine includes triethylamine and/or n-hexylamine.
Preferably, the cleaning solution of the washing include in toluene, ethyl alcohol or methanol any one or at least two it is mixed
Close object, the mixture illustratively include the mixture of toluene and ethyl alcohol, the mixture of toluene and methanol or toluene, methanol and
The mixture etc. of ethyl alcohol.
Preferably, step (b) organic solvent includes any one in hexamethylene, normal octane or toluene or at least two
The mixture of kind, the mixture illustratively includes the mixture of the mixture of hexamethylene and normal octane, toluene and hexamethylene
Or normal octane and the mixture of toluene etc..
Preferably, step (b) ionic liquid includes the anionic component and cationic components of the amount of equal substances.
Preferably, the cationic components include organic alcamines and/or organic amine.
Preferably, the Organic Alcohol amine includes diethanol amine and/or diisopropanolamine (DIPA).
Preferably, the organic amine includes diethylamine and/or dimethylamine.
Preferably, the anionic component includes hydrochloric acid and/or acetic acid.
Preferably, the preparation method of the ionic liquid include at room temperature face south ion component in be added equimolar amounts
The anionic component is mixed to get ionic liquid.
Preferably, the concentration of the ionic liquid aqueous solution be 0.1-2mol/L, such as 0.1mol/L, 0.5mol/L,
1mol/L or 2mol/L etc..
Preferably, the SiO of the ionic liquid aqueous solution and surface modification2Mass ratio be 1:(0.02-0.08), such as
1:0.02,1:0.03,1:0.04,1:0.05,1:0.06,1:0.07 or 1:0.08 etc..
Preferably, the volume ratio of the ionic liquid aqueous solution and organic solvent is 1:(1.5-5), such as 1:1.5,1:2,
1:3,1:4 or 1:5 etc..
Preferably, the formaldehyde is obtained by Formaldehyde Extraction with n-Octanol aqueous solution.
Preferably, the mass ratio of the n-octyl alcohol and formalin is 1:(1-3), such as 1:1,1:1.5,1:2,1:
2.5 or 1:3 etc., preferably 1:1.5.
Preferably, the temperature of the extraction is 30-50 DEG C, such as 30 DEG C, 35 DEG C, 40 DEG C, 45 DEG C or 50 DEG C etc., preferably
40℃。
Preferably, the time of the extraction is 1-2h, such as 1h, 1.5h or 2h etc..
Preferably, step (2) reaction is condensation reaction.
Preferably, the temperature of the condensation reaction is 35-45 DEG C, such as 35 DEG C, 37 DEG C, 40 DEG C, 42 DEG C or 45 DEG C etc..
Preferably, the molar ratio of the formaldehyde and propionic aldehyde is (1.1-1.2): 1, such as 1.1:1,1.15:1 or 1.2:1 etc..
Preferably, in the reaction mass propionic aldehyde concentration be 0.09-0.1mol/L, such as 0.09mol/L,
0.095mol/L or 0.1mol/L etc..
Preferably, the air speed of the reaction is 0.03-1.70h-1, such as 0.03h-1、0.16h-1、0.5h-1、1.13h-1Or
1.55h-1Deng.
As currently preferred technical solution, the described method comprises the following steps:
(1) under nitrogen protection, to Nano-meter SiO_22In sequentially add toluene, methyltrimethoxysilane and triethylamine, it
The return stirring 4-6h at 60-80 DEG C afterwards is dry under the conditions of being washed 3-4 times, 100-120 DEG C using toluene after centrifuge separation
To the Nano-meter SiO_2 of surface modification2；
(2) Nano-meter SiO_2 for the surface modification for obtaining step (1)2It is successively the two of 0.1-2mol/L with hexamethylene, concentration
Ethanol amine acetate aqueous solution is mixed to get Pickering emulsion；
(3) the Pickering emulsion for obtaining step (2) is added in fixed bed reactors, leads under the conditions of 35-45 DEG C
Enter the reaction mass reaction preparation methacrolein comprising formaldehyde and propionic aldehyde, the molar ratio of formaldehyde and propionic aldehyde is (1.1-1.2): 1,
Propanal concentration is 0.09-0.1mol/L in the reaction mass, and the air speed of the reaction is 0.03-1.70h-1。
Compared with the existing technology, the invention has the following advantages:
(1) the method for the invention is using Pickering emulsion as catalysis formaldehyde and propionic aldehyde reaction preparation methyl-prop
The catalyst of olefine aldehydr, and reaction process carries out in fixed bed reactors, to realize product and catalyst in preparation process
The real-time separation of active component, realizes the continuous operation of preparation process, while improving the utilization rate and catalysis of catalyst
Efficiency.
(2) the method for the invention does not find what demulsification and catalyst activity component were lost after preparation process carries out 72h
Phenomenon can be carried out continuous operation steady in a long-term.
(3) the method for the invention is using Pickering emulsion as catalysis formaldehyde and propionic aldehyde reaction preparation methyl-prop
The catalyst of olefine aldehydr increases the contact area of mobile phase reactant Yu aqueous catalysis active component, so that catalysis propionic aldehyde
The average conversion of conversion reaches as high as 100%, and the yield of methacrolein reaches as high as 90%.
Detailed description of the invention
Fig. 1 is optical microphotograph of the Pickering emulsion that is prepared of the embodiment of the present invention 1 before carrying out catalysis reaction
Mirror figure；
Fig. 2 is optical microphotograph of the Pickering emulsion that is prepared of the embodiment of the present invention 1 after carrying out catalysis reaction
Mirror figure.
Specific embodiment
The technical scheme of the invention is further explained by means of specific implementation.Those skilled in the art should be bright
, the described embodiments are merely helpful in understanding the present invention, should not be regarded as a specific limitation of the invention.
Embodiment 1
The method for preparing methacrolein:
(1) under nitrogen protection, the Nano-meter SiO_2 for being 50nm to vacuum-treated 1g partial size2In sequentially add 12mL first
Benzene, 0.4g methyltrimethoxysilane and 0.3g triethylamine, the return stirring 4h at 70 DEG C, after centrifuge separation, utilizes first later
Drying 12h obtains the Nano-meter SiO_2 of surface modification under the conditions of benzene washs 4 times, ethanol washing 2 times, 120 DEG C2；
(2) Nano-meter SiO_2 for the surface modification for obtaining 0.12g step (1)2Ultrasonic disperse is added in 5mL hexamethylene
3mL concentration is the diethanol amine acetate aqueous solution of 0.1mol/L, and vortex is mixed to get Pickering emulsion；
(3) the Pickering emulsion for obtaining step (2) is added in fixed bed reaction column, and standing loadings are 4cm3,
It is passed through under the conditions of 45 DEG C and reacts preparation methacrolein, the molar ratio of formaldehyde and propionic aldehyde comprising the reaction mass of formaldehyde and propionic aldehyde
For 1.1:1, propanal concentration is 0.1mol/L in the reaction mass, and the air speed of the reaction is 0.25h-1, the reaction time is
72h。
The propionic aldehyde average conversion of the present embodiment is 70%, and the yield of methacrolein is 23%.
The optical microscope such as Fig. 1 of the Pickering emulsion that the present embodiment is prepared before carrying out catalysis reaction
It is shown: by figure it can be seen that the water phase activity component wrapped up in the emulsion droplet of Pickering emulsion, Fig. 2 are to carry out catalysis reaction
Pickering emulsion afterwards, by figure it can also be seen that the water phase activity component wrapped up in the emulsion droplet of Pickering emulsion,
Comparison diagram 1 and Fig. 2 are it can be concluded that the active component in the emulsion droplet of reaction front and back Pickering emulsion can keep its shape substantially
Demulsifying phenomenon does not occur, while not occurring the phenomenon that grease layering in the product of fixed bed reaction column outflow for state, it may be said that
It is bright that when reaction carries out 72h, there is a phenomenon where the loss of active component of water phase yet.
Embodiment 2
The additional amount of methyltrimethoxysilane in embodiment 1 is replaced with 0.33g by the present embodiment, is washed without ethyl alcohol
Wash, by diethanol amine acetate aqueous solution it is isometric replace with the diethanol amine acetate aqueous solution that concentration is 0.5mol/L；
The air speed of reaction is replaced with into 0.375h-1；Other conditions are identical with embodiment 1.
The propionic aldehyde average conversion of the present embodiment is 100%, and the yield of methacrolein is 90%.
Embodiment 3
The present embodiment compared with Example 1, without ethanol washing, is replaced diethanol amine acetate aqueous solution is isometric
It is changed to the diethanol amine acetate aqueous solution that concentration is 2mol/L, the air speed of reaction is replaced with into 0.375h-1；Other conditions and reality
It is identical to apply example 1.
The propionic aldehyde average conversion of the present embodiment is 94%, and the yield of methacrolein is 75%.
Embodiment 4
Methyltrimethoxysilane in embodiment 1 is replaced with the vinyltrimethoxysilane of 0.59g by the present embodiment,
Without ethanol washing, by the Nano-meter SiO_2 of surface modification2Additional amount replace with 0.15g, by diethanol amine acetate aqueous solution
The diethylamine acetate aqueous solution for replacing with 0.5mol/L in equal volume, replaces with 0.375h for the air speed of reaction-1；Other conditions with
Embodiment 1 is compared to identical.
The propionic aldehyde average conversion of the present embodiment is 95%, and the yield of methacrolein is 81%.
Embodiment 5
Methyltrimethoxysilane in embodiment 1 is replaced with the propyl trimethoxy silicane of 0.49g by the present embodiment, not into
Row ethanol washing, by the Nano-meter SiO_2 of surface modification2Additional amount replace with 0.06g；Diethanol amine acetate aqueous solution is replaced
For the diethanol amine acetate aqueous solution of the 0.5mol/L of 1mL, other conditions are identical compared with Example 1.
The propionic aldehyde average conversion of the present embodiment is 100%, and the yield of methacrolein is 54%.
Embodiment 6
The additional amount of methyltrimethoxysilane in embodiment 1 is replaced with 0.48g by the present embodiment, is washed without ethyl alcohol
It washs, by the Nano-meter SiO_2 of surface modification2Additional amount replace with 0.0625g；Diethanol amine acetate aqueous solution replaces with 2.5mL
0.5mol/L diethylamine acetate aqueous solution, the concentration of propionic aldehyde replaces with 0.09mol/L, the air speed of reaction replaced with
0.375h-1；Other conditions are identical compared with Example 1.
The propionic aldehyde average conversion of the present embodiment is 94%, and the yield of methacrolein is 70%.
Embodiment 7
The method for preparing methacrolein:
(1) under nitrogen protection, the Nano-meter SiO_2 for being 7-40nm to vacuum-treated 1g partial size2In sequentially add 12mL
Toluene, 0.4g methyltrimethoxysilane and 0.3g triethylamine, the return stirring 4h at 80 DEG C, after centrifuge separation, utilizes later
Drying 12h obtains the Nano-meter SiO_2 of surface modification under the conditions of toluene washs 4 times, ethanol washing 2 times, 100 DEG C2；
(2) Nano-meter SiO_2 for the surface modification for obtaining 0.24g step (1)2Ultrasonic disperse is added in 10mL hexamethylene
6mL concentration is the diethanol amine acetate aqueous solution of 0.5mol/L, and vortex is mixed to get Pickering emulsion；
(3) the Pickering emulsion for obtaining step (2) is added in fixed bed reaction column, stands loadings and is
6.4cm3, it is passed through under the conditions of 45 DEG C and reacts preparation methacrolein, formaldehyde and propionic aldehyde comprising the reaction mass of formaldehyde and propionic aldehyde
Molar ratio be 1.2:1, propanal concentration is 0.09mol/L in the reaction mass, and the air speed of the reaction is 0.16h-1, reaction
Time is 72h.
The propionic aldehyde average conversion of the present embodiment is 89%, and the yield of methacrolein is 55%.
Embodiment 8
The method for preparing methacrolein:
(1) under nitrogen protection, the Nano-meter SiO_2 for being 50nm to vacuum-treated 1g partial size2In sequentially add 12mL first
Benzene, 0.4g methyltrimethoxysilane and 0.3g triethylamine, the return stirring 4h at 70 DEG C, after centrifuge separation, utilizes first later
Drying 12h obtains the Nano-meter SiO_2 of surface modification under the conditions of benzene washs 4 times, 120 DEG C2；
(2) Nano-meter SiO_2 for the surface modification for obtaining 0.24g step (1)2Ultrasonic disperse is added in 30mL hexamethylene
6mL concentration is the diethanol amine acetate aqueous solution of 0.5mol/L, and vortex is mixed to get Pickering emulsion；
(3) the Pickering emulsion for obtaining step (2) is added in fixed bed reaction column, stands loadings and is
1.3cm3, it is passed through under the conditions of 45 DEG C and reacts preparation methacrolein, formaldehyde and propionic aldehyde comprising the reaction mass of formaldehyde and propionic aldehyde
Molar ratio be 1.2:1, propanal concentration is 0.09mol/L in the reaction mass, and the air speed of the reaction is 1.7h-1, reaction
Time is 72h.
The propionic aldehyde average conversion of the present embodiment is 49%, and the yield of methacrolein is 20%.
Embodiment 9
The standing loadings of embodiment 8 are replaced with 14.4cm by the present embodiment3, air speed replaces with 0.03h-1；Other conditions
It is identical compared with Example 8.
The propionic aldehyde average conversion of the present embodiment is 92%, and the yield of methacrolein is 62%.
Embodiment 10
The method for preparing methacrolein:
(1) under nitrogen protection, the Nano-meter SiO_2 for being 500nm to vacuum-treated 1g partial size2In sequentially add 12mL first
Benzene, 0.4g methyltrimethoxysilane and 0.3g triethylamine, the return stirring 4h at 70 DEG C, after centrifuge separation, utilizes first later
Benzene washs 4 times, and drying 12h obtains the Nano-meter SiO_2 of surface modification under the conditions of methanol washs 2 times, 100 DEG C2；
(2) Nano-meter SiO_2 for the surface modification for obtaining 0.075g step (1)2Ultrasonic disperse is added in 5mL hexamethylene
3mL concentration is the diethanol amine acetate aqueous solution of 0.5mol/L, and vortex is mixed to get Pickering emulsion；
(3) the Pickering emulsion for obtaining step (2) is added in fixed bed reaction column, and standing loadings are 4cm3,
It is passed through under the conditions of 35 DEG C and reacts preparation methacrolein, the molar ratio of formaldehyde and propionic aldehyde comprising the reaction mass of formaldehyde and propionic aldehyde
For 1.2:1, propanal concentration is 0.1mol/L in the reaction mass, and the air speed of the reaction is 0.75h-1, the reaction time is
72h。
The propionic aldehyde average conversion of the present embodiment is 67%, and the yield of methacrolein is 46%.
Performance test methods:
The propionic aldehyde average conversion of the method for methacrolein and the yield of methacrolein are prepared described in embodiment 1-10
Calculation method it is as follows:
Propionic aldehyde average conversion (%)=(amount of the substance of the unreacted propionic aldehyde of the amount-of the substance of the propionic aldehyde of addition)/add
Amount × 100% of the substance of the propionic aldehyde entered；
The amount of the substance of amount/addition propionic aldehyde of the substance of methacrolein yield (%)=generation methacrolein ×
100%.
Comparative example 1-3 can be seen that propionic aldehyde average conversion of the concentration to preparation process of ionic liquid aqueous solution
It is affected with the yield of methacrolein, the concentration for properly increasing ionic liquid aqueous solution is conducive to improve the activity of catalyst
With the selectivity to methacrolein.Comparative example 2,4-6 can be seen that active component concentration under the same conditions, one
Determine the type and additional amount that change coating material in range, so that propionic aldehyde average conversion can reach 100%, methyl-prop
The yield of olefine aldehydr is 54%-90%；Comparative example 8-9 can be seen that activity of the standing loadings to catalyst of catalyst
It is affected, the standing loadings for properly increasing catalyst can significantly improve the receipts of propionic aldehyde average conversion and methacrolein
Rate.
Demulsification does not occur in 72h after preparation process starts for embodiment 1-10 the method and water phase activity component is lost
The phenomenon that, illustrate that the method for the invention can be operated continuously, improves the utilization rate of catalytic active component.And embodiment 1-
10 have been prepared methacrolein, illustrate that the method for the invention prepares the side of methacrolein on fixed bed reactors
Method is feasible.
The Applicant declares that the foregoing is merely a specific embodiment of the invention, but protection scope of the present invention not office
It is limited to this, it should be clear to those skilled in the art, any to belong to those skilled in the art and take off in the present invention
In the technical scope of dew, any changes or substitutions that can be easily thought of, and all of which fall within the scope of protection and disclosure of the present invention.
Claims (9)
1. a kind of method for preparing methacrolein, which is characterized in that the method is using Pickering emulsion as catalysis
Formaldehyde and propionic aldehyde reaction preparation methacrolein catalyst, and the preparation process of the method in fixed bed reactors into
Row.
2. the method as described in claim 1, which is characterized in that the Pickering emulsion includes the nanometer of surface modification
SiO2, ionic liquid aqueous solution and organic solvent.
3. method according to claim 1 or 2, which is characterized in that the described method comprises the following steps:
(1) preparation of Pickering emulsion；
(2) the Pickering emulsion obtained step (1) is added in fixed bed reactors, is passed through comprising formaldehyde and propionic aldehyde
Reaction mass reaction preparation methacrolein.
4. method as claimed in claim 3, which is characterized in that the preparation of Pickering emulsion described in step (1) includes
Following steps:
(a) Nano-meter SiO_22Surface modification；
(b) Nano-meter SiO_2 for the surface modification for obtaining step (a)2Successively it is mixed to get with organic solvent and ionic liquid aqueous solution
Pickering emulsion；
Preferably, step (a) Nano-meter SiO_22Surface modification include under nitrogen protection, to Nano-meter SiO_22In sequentially add
Toluene, coating material and organic amine, return stirring later, after solid-liquor separation, washing is dried to obtain the nanometer of surface modification
SiO2；
Preferably, the temperature of the return stirring is 60-80 DEG C；
Preferably, the time of the return stirring is 4-6h；
Preferably, the temperature of the drying is 100-120 DEG C.
5. method as claimed in claim 4, which is characterized in that the Nano-meter SiO_22Partial size be 7-500nm；
Preferably, the coating material includes methyltrimethoxysilane, vinyltrimethoxysilane, propyl trimethoxy
In silane, trimethoxysilane or phenyltrimethoxysila,e any one or at least two mixture；
Preferably, the mole and Nano-meter SiO_2 of the coating material2Mass ratio be 1-4mmol/g；
Preferably, the organic amine includes triethylamine and/or n-hexylamine；
Preferably, the cleaning solution of the washing include in toluene, ethyl alcohol or methanol any one or at least two mixture.
6. method as described in claim 4 or 5, which is characterized in that step (b) organic solvent includes hexamethylene, just pungent
In alkane or toluene any one or at least two mixture；
Preferably, step (b) ionic liquid includes the anionic component and cationic components of the amount of equal substances；
Preferably, the cationic components include organic alcamines and/or organic amine；
Preferably, the Organic Alcohol amine includes diethanol amine and/or diisopropanolamine (DIPA)；
Preferably, the organic amine includes diethylamine and/or dimethylamine；
Preferably, the anionic component includes hydrochloric acid and/or acetic acid；
Preferably, the preparation method of the ionic liquid include at room temperature face south ion component in be added equimolar amounts yin from
Subgroup point is mixed to get ionic liquid；
Preferably, the concentration of the ionic liquid aqueous solution is 0.1-2mol/L；
Preferably, the SiO of the ionic liquid aqueous solution and surface modification2Mass ratio be 1:(0.02-0.08)；
Preferably, the volume ratio of the ionic liquid aqueous solution and organic solvent is 1:(1.5-5).
7. as the method according to claim 1 to 6, which is characterized in that the formaldehyde is by Formaldehyde Extraction with n-Octanol aqueous solution
It obtains；
Preferably, the mass ratio of the n-octyl alcohol and formalin is 1:(1-3), preferably 1:1.5；
Preferably, the temperature of the extraction is 30-50 DEG C, preferably 40 DEG C；
Preferably, the time of the extraction is 1-2h.
8. such as the described in any item methods of claim 3-7, which is characterized in that step (2) reaction is condensation reaction；
Preferably, the temperature of the condensation reaction is 35-45 DEG C；
Preferably, the molar ratio of the formaldehyde and propionic aldehyde is (1.1-1.2): 1；
Preferably, the concentration of propionic aldehyde is 0.09-0.1mol/L in the reaction mass；
Preferably, the air speed of the reaction is 0.03-1.70h-1。
9. the method according to claim 1, which is characterized in that the described method comprises the following steps:
(1) under nitrogen protection, to Nano-meter SiO_22In sequentially add toluene, methyltrimethoxysilane and triethylamine, Zhi Hou
Return stirring 4-6h at 60-80 DEG C after centrifuge separation, is dried to obtain table under the conditions of washing 3-4 times, 100-120 DEG C using toluene
The Nano-meter SiO_2 of face modification2；
(2) Nano-meter SiO_2 for the surface modification for obtaining step (1)2It is successively the diethanol of 0.1-2mol/L with hexamethylene, concentration
Amine acetate aqueous solution is mixed to get Pickering emulsion；
(3) the Pickering emulsion for obtaining step (2) is added in fixed bed reactors, and packet is passed through under the conditions of 35-45 DEG C
It is reacted containing the reaction mass of formaldehyde and propionic aldehyde and prepares methacrolein, the molar ratio of formaldehyde and propionic aldehyde is (1.1-1.2): 1, it is described
Propanal concentration is 0.09-0.1mol/L in reaction mass, and the air speed of the reaction is 0.03-1.70h-1。
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| CN111632629A (en) * | 2020-06-23 | 2020-09-08 | 中国科学院过程工程研究所 | Method for recovering ionic liquid catalyst in preparation process of coal-based methacrolein |
| CN114733571A (en) * | 2022-05-19 | 2022-07-12 | 郑州大学 | Catalyst for preparing methylacrolein and preparation method thereof |
| CN116082136A (en) * | 2022-12-26 | 2023-05-09 | 沈阳科创化学品有限公司 | Preparation method of olefine aldehyde compound |
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| CN116082136A (en) * | 2022-12-26 | 2023-05-09 | 沈阳科创化学品有限公司 | Preparation method of olefine aldehyde compound |
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