A kind of catalyst of toluene direct oxidation producing benzaldehyde and preparation method thereof
Technical field
The present invention relates to a kind of catalyst, more particularly to a kind of catalyst of toluene direct oxidation producing benzaldehyde and its preparation
Method, belong to industrial catalysis technical field.
Background technology
Benzaldehyde is a kind of important fine chemical product, is widely used in medicine, dyestuff, spices, agricultural chemicals and material etc.
In industrial circle.The presently disclosed production method for preparing benzaldehyde mainly has following three kinds:Chlorination toluene Hydrolyze method, benzoic acid
(ester) reducing process and toluene direct oxidation method.
Inevitably contain chlorine in the benzaldehyde that chlorination toluene Hydrolyze method is produced, and be used in the industries such as medicine and spices
Chlorine can not be contained in benzaldehyde, therefore the application of the benzaldehyde produced by chlorinolysis receives certain limit
System.Benzoic acid reducing process refers to the method for generating benzaldehyde by catalytic hydrogenating reduction by benzoic acid or benzoic ether, although
The conversion ratio and selectivity of this method are all very high, but the reaction temperature of benzoic ether reducing process must reach more than 300 DEG C, energy
Consumption is very big, very uneconomical.
Toluene direct oxidation generation benzaldehyde under gas phase or liquid-phase condition is relatively inexpensive and environmentally friendly method, China
Patent CN1068755 discloses a kind of method that benzaldehyde is prepared by gas phase oxidation of toluene, is prepared by this method
The selectivity of benzaldehyde reaches 60%, and the once through yield of benzaldehyde can reach 16%, the side that toluene passes through vapor phase method direct oxidation
Method is primarily present reaction temperature height, the defects of toluene easy over oxidation, the selectivity decline of benzaldehyde when improving conversion ratio
It is especially apparent.Report on direct oxidation generation benzaldehyde under liquid-phase condition was a lot, early in Patent No. in 2004
CN1528726 Chinese patent discloses a kind of in acid or neutral ion liquid and acetic acid in the mixed solvent, passes through liquid phase
Toluene is aoxidized to prepare the method for benzaldehyde, toluene is aoxidized under the conditions of 115~120 DEG C, when toluene conversion is 42%, benzene
The selectivity of formaldehyde is only 48%, and the method has widely applied the ionic liquid and acetate solvate of costliness, substantially increases and is produced into
This, and product separation is difficult, industrial production is uneconomical, and Dalian Chemistry and Physics Institute patent CN02143361.5 discloses one kind and is used for toluene
Aoxidize the preparation method of the catalyst of producing benzaldehyde, the active component of the catalyst is zirconium and other transition metal, alkali metal or
Alkaline-earth metal etc., using the catalyst, in 180-195 DEG C of temperature, oxygen is passed through, is reacted under the conditions of pressure 0.8-1.2MPa,
When toluene conversion is 13%, the selectivity of benzaldehyde is 86.6%, and the preparation technology of this method catalyst is more complicated, and
Oxidation is difficult to control the stage in aldehyde, is more easy to generate benzoic acid.
In summary, there is presently no one kind reaction is simple, energy-conserving and environment-protective, product and solvent is easily separated and recovery, reaction
In toluene conversion and benzaldehyde selectivity higher production benzaldehyde simultaneously method.
Layered double hydroxide (LDHs) is a kind of anion lamellar compound, also known as hydrotalcite, and LDHs is by layer
Between anion and the accumulation of positively charged laminate form, there is the structure that can be embedded in anion, LDHs structure such as sandwich
Shape, both sides are made up of the metal ion positive charge piece of divalence and trivalent, and centre is anion and hydrone, when LDHs is heated to
At 450~500 DEG C, dehydration is more complete, generation bimetal composite oxide (LDO), in heating process, LDHs orderly layer
Shape is destructurized, surface area increase, pore volume increase, therefore the LDO formed is very suitable for by carrier making as catalyst
With.
The content of the invention
The present invention is directed to the deficiency of toluene conversion and benzaldehyde selectivity in existing toluene direct oxidation method, there is provided one
Catalyst of kind toluene direct oxidation producing benzaldehyde and preparation method thereof.
The technical scheme that the present invention solves above-mentioned technical problem is as follows:
A kind of catalyst of toluene direct oxidation producing benzaldehyde, it is characterised in that including following component:
The beneficial effects of the invention are as follows:The present invention provide it is a kind of using magnesia, alumina composite oxide as carrier first
The catalyst of benzene direct oxidation producing benzaldehyde, the catalyst have high toluene conversion, benzaldehyde selectivity and stable reaction
Property, excellent performance, reaction condition is gentle, and is in reactant and product in two-phase, is easily isolated and purifies.
The present invention also provides a kind of preparation method of the catalyst of toluene direct oxidation producing benzaldehyde, comprises the following steps:
1) carrier is prepared:The magnesium salts of solubility and aluminium salt are placed in deionized water dissolving are configured to total concentration and be
0.5mol/L solution A, aqueous slkali B is added dropwise in solution A under constant agitation, keeps pH value of solution in the process
Value 9~10, aqueous slkali B continue stirring ageing 3~5 hours, filtering, wash to neutrality, dry repeatedly after being added dropwise, 450~
550 DEG C are calcined to obtain magnesia alumina composite oxide catalysts carrier;
2) cerium and cobalt are impregnated:The carrier of gained in step 1) is impregnated with the mixed solution of soluble cerium salt and cobalt salt, done
It is dry, it is calcined after grinding at 500~600 DEG C;
3) copper and mickel is impregnated:The mixed solution of products obtained therefrom soluble copper salt and nickel salt in step 2) is impregnated, dried,
It is calcined after grinding at 500~600 DEG C.
Further, aluminium salt described in step 1) and magnesium salts are aluminum nitrate and magnesium nitrate, and the aqueous slkali is that sodium hydroxide is molten
Liquid.
Further, the soluble cerium salt described in step 2) is cerous nitrate or Cericammoniumsulfate, and soluble cobalt is nitric acid
Cobalt and cobaltous sulfate.
Further, the soluble copper salt described in step 3) is copper nitrate, and soluble nickel salt is nickel nitrate.
The preparation method of the catalyst of the toluene direct oxidation producing benzaldehyde of the present invention produces after using LDHs baking heats
LDO as catalyst carrier, the bigger serface and the coordinated of pore volume and bimetallic oxide that make full use of LDO are made
With afterwards using step impregnation method, first dipping cerium and cobalt, impregnate copper and mickel, this preparation method can improve cerium, cobalt, copper afterwards
With nickel in the decentralization and valence stability of carrier surface, give full play between each metallic atom and carrier magnesia, aluminum oxide
Coordinated effect, strengthen metal-auxiliary agent-carrier between interaction.
Embodiment
The principle and feature of the present invention are described below in conjunction with example, the given examples are served only to explain the present invention, and
It is non-to be used to limit the scope of the present invention.
Embodiment 1:
A kind of catalyst of toluene direct oxidation producing benzaldehyde, including following component:Magnesia alumina composite oxides
Carrier 80wt%, wherein magnesia and aluminum oxide mol ratio are 1, cerium 10wt%, cobalt 3wt%, copper 5wt%, nickel 2wt%.
The preparation method of above-mentioned catalyst comprises the following steps:
1) 150g Al (NO are weighed3)3·9H2O and 51.3g Mg (NO3)2·6H2O is dissolved in 1200mL deionized waters, is matched somebody with somebody
It is 0.5molL that total concentration, which is made,-1Mixing salt solution, weigh 80g NaOH and be dissolved in 400ml deionized waters and be configured to
5mol·L-1NaOH solution, NaOH solution is added dropwise in mixing salt solution under agitation, during dropwise addition
System pH is kept 9~10, NaOH solution continues stirring ageing 3 hours after being added dropwise, products therefrom is filtered, using going
Ionized water is washed 3 times repeatedly, is placed in 100 DEG C of thermostatic drying chambers and is dried, and ground be placed in 450 DEG C of Muffle furnaces roasts after the completion of drying
Burn 5 hours to obtain catalyst carrier;
2) 38.8g Ce (NO are weighed3)3·6H2O and 0.76gCo (NO3)2·6H2O is dissolved in 200mL deionized waters, is taken
The catalyst carrier of gained, the Ce (NO that will be prepared in 100g steps 1)3)3·6H2O and Co (NO3)2·6H2The O aqueous solution is not
The disconnected lower impregnated catalyst support of stirring, after catalyst be placed in 100 DEG C of baking ovens dried, it is ground to be calcined 3 at 500 DEG C
Hour;
3) 18.3g Cu (NO are weighed3)2With 12.4g Ni (NO3)2·6H2O is dissolved in 100ml deionized waters, will be prepared
Aqueous solution impregnation steps 2) in be calcined after product, be placed on afterwards in 100 DEG C of baking ovens dry, it is ground at 550 DEG C
Roasting obtains catalyst A in 2 hours.
Embodiment 2:
A kind of catalyst of toluene direct oxidation producing benzaldehyde, including following component:Magnesia alumina composite oxides
Carrier 90wt%, wherein magnesia and aluminum oxide mol ratio are 1, cerium 4wt%, cobalt 5wt%, copper 0.5wt%, nickel 0.5wt%.
The preparation method of above-mentioned catalyst comprises the following steps:
1) 150g Al (NO are weighed3)3·9H2O and 51.3gMg (NO3)2·6H2O is dissolved in 1200mL deionized waters, is prepared
It is 0.5molL into total concentration-1Mixing salt solution, weigh 80g NaOH and be dissolved in 400ml deionized waters and be configured to 5mol
L-1NaOH solution, NaOH solution is added dropwise in mixing salt solution under agitation, the keeping body during dropwise addition
It is pH value 9~10, NaOH solution continues stirring ageing 3 hours after being added dropwise, products therefrom is filtered, uses deionized water
Wash repeatedly 3 times, be placed in 100 DEG C of thermostatic drying chambers and dry, ground after the completion of drying to be placed in 500 DEG C of Muffle kiln roastings 5 small
When obtain catalyst carrier;
2) 13.8g Ce (NO are weighed3)3·6H2O and 27.4gCo (NO3)2·6H2O is dissolved in 200mL deionized waters, is taken
The catalyst carrier of gained, the Ce (NO that will be prepared in 100g steps 1)3)3·6H2O and Co (NO3)2·6H2The O aqueous solution is not
The disconnected lower impregnated catalyst support of stirring, after catalyst be placed in 100 DEG C of baking ovens dried, it is ground to be calcined 2 at 600 DEG C
Hour;
3) 1.61g Cu (NO are weighed3)2With 2.72g Ni (NO3)2·6H2O is dissolved in 100ml deionized waters, will be prepared
Aqueous solution impregnation steps 2) in be calcined after product, be placed on afterwards in 100 DEG C of baking ovens dry, it is ground at 500 DEG C
Roasting obtains catalyst B in 2 hours.
Embodiment 3:
A kind of catalyst of toluene direct oxidation producing benzaldehyde, including following component:Magnesia alumina composite oxides
Carrier 85wt%, wherein magnesia and aluminum oxide mol ratio are 2, cerium 6wt%, cobalt 5wt%, copper 3wt%, nickel 1wt%.
The preparation method of above-mentioned catalyst comprises the following steps:
1) 39.9g AlCl are weighed3With 28.8g MgCl2It is dissolved in 1200mL deionized waters, being configured to total concentration is
0.5mol·L-1Mixing salt solution, weigh 80g NaOH and be dissolved in 400ml deionized waters and be configured to 5molL-1NaOH it is molten
Liquid, NaOH solution is added dropwise in mixing salt solution under agitation, kept during dropwise addition system pH 9~
10, NaOH solution continues stirring ageing 3 hours after being added dropwise, products therefrom is filtered, washed repeatedly using deionized water 3 times,
Be placed in 100 DEG C of thermostatic drying chambers and dry, after the completion of drying it is ground be placed in 550 DEG C of Muffle kiln roastings 3 hours catalyst
Carrier;
2) 30.1g (NH are weighed4)4Ce(SO4)4With 28g CoSO4·7H2O is dissolved in 200mL deionized waters, takes 100g to walk
The catalyst carrier of rapid 1) middle the gained, (NH that will be prepared4)4Ce(SO4)4And CoSO4·7H2The O aqueous solution is in the case where being stirred continuously
Impregnated catalyst support, after by catalyst be placed in 100 DEG C of baking ovens dry, it is ground to be calcined 2 hours at 600 DEG C;
3) 10.3g Cu (NO are weighed3)2With 5.8g Ni (NO3)2·6H2O is dissolved in 100ml deionized waters, by what is prepared
Aqueous solution impregnation steps 2) in be calcined after product, be placed on afterwards in 100 DEG C of baking ovens dry, it is ground to be roasted at 550 DEG C
Burn 2 hours and obtain catalyst C.
Embodiment 4:
A kind of catalyst of toluene direct oxidation producing benzaldehyde, including following component:Magnesia alumina composite oxides
Carrier 95wt%, wherein magnesia and aluminum oxide mol ratio are 2, cerium 0.5wt%, cobalt 0.5wt%, copper 2wt%, nickel 2wt%.
The preparation method of above-mentioned catalyst comprises the following steps:
1) 39.9g AlCl are weighed3With 28.8g MgCl2It is dissolved in 1200mL deionized waters, being configured to total concentration is
0.5mol·L-1Mixing salt solution, weigh 80g NaOH and be dissolved in 400ml deionized waters and be configured to 5molL-1NaOH it is molten
Liquid, NaOH solution is added dropwise in mixing salt solution under agitation, kept during dropwise addition system pH 9~
10, NaOH solution continues stirring ageing 3 hours after being added dropwise, products therefrom is filtered, washed repeatedly using deionized water 3 times,
Be placed in 100 DEG C of thermostatic drying chambers and dry, after the completion of drying it is ground be placed in 550 DEG C of Muffle kiln roastings 3 hours catalyst
Carrier;
2) 2.2g (NH are weighed4)4Ce(SO4)4With 2.52g CoSO4·7H2O is dissolved in 200mL deionized waters, takes 100g to walk
The catalyst carrier of rapid 1) middle the gained, (NH that will be prepared4)4Ce(SO4)4And 2.52gCoSO4·7H2The O aqueous solution is constantly stirring
Mix lower impregnated catalyst support, after catalyst be placed in 100 DEG C of baking ovens dried, the ground roasting at 550 DEG C is 3 small
When;
3) 6.2g Cu (NO are weighed3)2With 10.4g Ni (NO3)2·6H2O is dissolved in 100ml deionized waters, by what is prepared
Aqueous solution impregnation steps 2) in be calcined after product, be placed on afterwards in 100 DEG C of baking ovens dry, it is ground to be roasted at 600 DEG C
Burn 2 hours and obtain catalyst D.
Gained catalyst in embodiment 1-4 is used in the reaction of toluene direct oxidation producing benzaldehyde, reacted in the anti-of 1.0L
Answer in kettle and carry out, add 50g toluene, 5g catalyst and 500ml acetone and close kettle closedtop as solvent, mixing speed 800r/
Min, 110 DEG C are heated to, blowing air is reacted, and reaction temperature rises to 120 DEG C and controlled is reacted in this temperature, reactant
It is Stress control in 5MPa, in 5 hours reaction time, after reaction terminates, reaction system is down to room temperature, opens kettle cover, sampling point
Analysis.Response data is shown in Table 1.
Table 1:The reactivity data of gained catalyst in embodiment 1-4
The foregoing is only presently preferred embodiments of the present invention, be not intended to limit the invention, it is all the present invention spirit and
Within principle, any modification, equivalent substitution and improvements made etc., it should be included within the protection domain of invention.