Background technology
Benzaldehyde is a kind of important fine chemical product, is widely used in the industrial circles such as medicine, dyestuff, spices, agricultural chemicals and material.The production method preparing benzaldehyde now mainly contains following three kinds: chlorination toluene Hydrolyze method, benzoic acid (ester) reducing process and toluene direct oxidation method.
Inevitably containing chlorine in the benzaldehyde that chlorination toluene Hydrolyze method is produced, and for not containing chlorine in benzaldehyde in the industries such as medicine and spices, the range of application of the benzaldehyde therefore produced by chlorinolysis receives certain restriction.Benzoic acid reducing process refers to and generates the method for benzaldehyde by benzoic acid or benzoic ether by catalytic hydrogenating reduction, although the conversion ratio of this method and selective all very high, but the reaction temperature of benzoic ether reducing process must reach more than 300 DEG C, energy consumption is very large, very uneconomical.
Toluene direct oxidation under gas phase or liquid-phase condition generates the method that benzaldehyde is comparatively economy and environmental protection, Chinese patent CN1068755 discloses a kind of method being prepared benzaldehyde by gas phase oxidation of toluene, the selective of the benzaldehyde prepared by the method reaches 60%, the once through yield of benzaldehyde can reach 16%, it is high mainly to there is reaction temperature by the method for vapor phase method direct oxidation in toluene, the defect of the easy over oxidation of toluene, when improving conversion ratio, the selective decline of benzaldehyde is especially obvious.The report generating benzaldehyde about direct oxidation under liquid-phase condition is a lot, disclose a kind of in acid or neutral ion liquid and acetic acid mixed solvent as far back as the patent No. in 2004 Chinese patent that is CN1528726, the method of benzaldehyde is prepared by liquid phase oxidation toluene, toluene is oxidized under 115 ~ 120 DEG C of conditions, when toluene conversion is 42%, the selective of benzaldehyde is only 48%, this method has widely applied expensive ionic liquid and acetate solvate, substantially increase production cost, and separation of products is difficult, industrial production is uneconomical, Dalian Chemistry and Physics Institute patent CN02143361.5 discloses a kind of preparation method of the catalyst for toluene oxidation producing benzaldehyde, the active component of this catalyst is zirconium and other transition metal, alkali metal or alkaline-earth metal etc., use this catalyst, at temperature 180-195 DEG C, pass into oxygen, react under pressure 0.8-1.2MPa condition, when toluene conversion is 13%, the selective of benzaldehyde is 86.6%, preparation technology's more complicated of the method catalyst, and be oxidized the wayward stage at aldehyde, more easily generate benzoic acid.
In sum, also there is no that a kind of reaction is simple at present, energy-conserving and environment-protective, a product and solvent is easily separated and reclaim, the toluene conversion in reaction and benzaldehyde selective while higher production benzaldehyde method.
Layered double hydroxide (LDHs) is an anionoid lamellar compound, also known as hydrotalcite, LDHs is piled up by interlayer anion and positively charged laminate and forms, there is the structure that can embed anion, the structure of LDHs is as cappelletti bag-like, both sides are made up of the metal ion positive charge sheet of divalence and trivalent, centre is anion and hydrone, when LDHs is heated to 450 ~ 500 DEG C, dewater more complete, generate bimetal composite oxide (LDO), in heating process, the ordered lamellar structure of LDHs is destroyed, surface area increases, pore volume increases, therefore the LDO formed is very suitable for being used by carrier as catalyst.
Summary of the invention
The present invention is directed to toluene conversion and benzaldehyde in existing toluene direct oxidation method optionally not enough, a kind of Catalysts and its preparation method of toluene direct oxidation producing benzaldehyde is provided.
The technical scheme that the present invention solves the problems of the technologies described above is as follows:
A catalyst for toluene direct oxidation producing benzaldehyde, is characterized in that, comprises following component:
The invention has the beneficial effects as follows: the invention provides a kind of with the catalyst of magnesia, the alumina composite oxide toluene direct oxidation producing benzaldehyde that is carrier, this catalyst has the selective and reaction stability of high toluene conversion, benzaldehyde, excellent performance, reaction condition is gentle, and be in two-phase with reactant and product, be easy to isolation andpurification.
The present invention also provides a kind of preparation method of catalyst of toluene direct oxidation producing benzaldehyde, comprises the steps:
1) carrier is prepared: the magnesium salts of solubility and aluminium salt are placed in deionized water dissolving and are mixed with the solution A that total concentration is 0.5mol/L, under constant agitation aqueous slkali B is dropwise added in solution A, keep solution ph 9 ~ 10 in the process, aqueous slkali B dropwises rear continuation and stirs ageing 3 ~ 5 hours, filter, cyclic washing is to neutral, and dry, 450 ~ 550 DEG C of roastings obtain magnesia alumina composite oxide catalysts carrier;
2) flood cerium and cobalt: by step 1) in the carrier solubility cerium salt of gained and the mixed solution dipping of cobalt salt, dry, roasting at 500 ~ 600 DEG C after grinding;
3) flood copper and mickel: by step 2) in the mixed solution dipping of products obtained therefrom soluble copper salt and nickel salt, dry, roasting at 500 ~ 600 DEG C after grinding.
Further, step 1) described in aluminium salt and magnesium salts be aluminum nitrate and magnesium nitrate, described aqueous slkali is sodium hydroxide solution.
Further, step 2) described in solubility cerium salt be cerous nitrate or Cericammoniumsulfate, soluble cobalt is cobalt nitrate and cobaltous sulfate.
Further, step 3) described in soluble copper salt be copper nitrate, soluble nickel salt is nickel nitrate.
The LDO produced after the preparation method of the catalyst of toluene direct oxidation producing benzaldehyde of the present invention adopts LDHs baking heat is as catalyst carrier, make full use of the Large ratio surface sum pore volume of LDO and the coordinated effect of bimetallic oxide, adopt step impregnation method afterwards, first flood cerium and cobalt, rear dipping copper and mickel, this preparation method can improve cerium, cobalt, copper and mickel is at the decentralization of carrier surface and valence stability, give full play to each metallic atom and carrier magnesia, coordinated effect between aluminium oxide, strengthen the interaction between metal-auxiliary agent-carrier.
Detailed description of the invention
Be described principle of the present invention and feature below in conjunction with example, example, only for explaining the present invention, is not intended to limit scope of the present invention.
Embodiment 1:
A catalyst for toluene direct oxidation producing benzaldehyde, comprises following component: magnesia alumina composite oxide carrier 80wt%, and wherein the mol ratio of magnesia and aluminium oxide is 1, cerium 10wt%, cobalt 3wt%, copper 5wt%, nickel 2wt%.
The preparation method of above-mentioned catalyst comprises the steps:
1) 150gAl (NO is taken
3)
39H
2o and 51.3gMg (NO
3)
26H
2o is dissolved in 1200mL deionized water, and being mixed with total concentration is 0.5molL
-1mixing salt solution, take 80gNaOH and be dissolved in 400ml deionized water and be mixed with 5molL
-1naOH solution, under agitation NaOH solution is dropwise joined in mixing salt solution, in dropping process, keep system pH 9 ~ 10, NaOH solution dropwises rear continuation and stirs ageing 3 hours, products therefrom is filtered, use deionized water repeatedly to wash 3 times, be placed in 100 DEG C of thermostatic drying chambers dry, be placed in 450 DEG C of Muffle furnace roastings through grinding after drying completes and obtain catalyst carrier in 5 hours;
2) 38.8gCe (NO is taken
3)
36H
2o and 0.76gCo (NO
3)
26H
2o is dissolved in 200mL deionized water, gets 100g step 1) in the catalyst carrier of gained, by the Ce (NO prepared
3)
36H
2o and Co (NO
3)
26H
2the O aqueous solution is impregnated catalyst support under constantly stirring, after catalyst to be placed in 100 DEG C of baking ovens dry, through grinding roasting 3 hours at 500 DEG C;
3) 18.3gCu (NO is taken
3)
2with 12.4gNi (NO
3)
26H
2o is dissolved in 100ml deionized water, the aqueous impregnation step 2 by preparing) in product after roasting, be placed in 100 DEG C of baking ovens dry afterwards, within 2 hours, obtain catalyst A through grinding roasting at 550 DEG C.
Embodiment 2:
A catalyst for toluene direct oxidation producing benzaldehyde, comprises following component: magnesia alumina composite oxide carrier 90wt%, and wherein the mol ratio of magnesia and aluminium oxide is 1, cerium 4wt%, cobalt 5wt%, copper 0.5wt%, nickel 0.5wt%.
The preparation method of above-mentioned catalyst comprises the steps:
1) 150gAl (NO is taken
3)
39H
2o and 51.3gMg (NO
3)
26H
2o is dissolved in 1200mL deionized water, and being mixed with total concentration is 0.5molL
-1mixing salt solution, take 80gNaOH and be dissolved in 400ml deionized water and be mixed with 5molL
-1naOH solution, under agitation NaOH solution is dropwise joined in mixing salt solution, in dropping process, keep system pH 9 ~ 10, NaOH solution dropwises rear continuation and stirs ageing 3 hours, products therefrom is filtered, use deionized water repeatedly to wash 3 times, be placed in 100 DEG C of thermostatic drying chambers dry, be placed in 500 DEG C of Muffle furnace roastings through grinding after drying completes and obtain catalyst carrier in 5 hours;
2) 13.8gCe (NO is taken
3)
36H
2o and 27.4gCo (NO
3)
26H
2o is dissolved in 200mL deionized water, gets 100g step 1) in the catalyst carrier of gained, by the Ce (NO prepared
3)
36H
2o and Co (NO
3)
26H
2the O aqueous solution is impregnated catalyst support under constantly stirring, after catalyst to be placed in 100 DEG C of baking ovens dry, through grinding roasting 2 hours at 600 DEG C;
3) 1.61gCu (NO is taken
3)
2with 2.72gNi (NO
3)
26H
2o is dissolved in 100ml deionized water, the aqueous impregnation step 2 by preparing) in product after roasting, be placed in 100 DEG C of baking ovens dry afterwards, within 2 hours, obtain catalyst B through grinding roasting at 500 DEG C.
Embodiment 3:
A catalyst for toluene direct oxidation producing benzaldehyde, comprises following component: magnesia alumina composite oxide carrier 85wt%, and wherein the mol ratio of magnesia and aluminium oxide is 2, cerium 6wt%, cobalt 5wt%, copper 3wt%, nickel 1wt%.
The preparation method of above-mentioned catalyst comprises the steps:
1) 39.9gAlCl is taken
3and 28.8gMgCl
2be dissolved in 1200mL deionized water, being mixed with total concentration is 0.5molL
-1mixing salt solution, take 80gNaOH and be dissolved in 400ml deionized water and be mixed with 5molL
-1naOH solution, under agitation NaOH solution is dropwise joined in mixing salt solution, in dropping process, keep system pH 9 ~ 10, NaOH solution dropwises rear continuation and stirs ageing 3 hours, products therefrom is filtered, use deionized water repeatedly to wash 3 times, be placed in 100 DEG C of thermostatic drying chambers dry, be placed in 550 DEG C of Muffle furnace roastings through grinding after drying completes and obtain catalyst carrier in 3 hours;
2) 30.1g (NH is taken
4)
4ce (SO
4)
4and 28gCoSO
47H
2o is dissolved in 200mL deionized water, gets 100g step 1) in the catalyst carrier of gained, by (the NH prepared
4)
4ce (SO
4)
4and CoSO
47H
2the O aqueous solution is impregnated catalyst support under constantly stirring, after catalyst to be placed in 100 DEG C of baking ovens dry, through grinding roasting 2 hours at 600 DEG C;
3) 10.3gCu (NO is taken
3)
2with 5.8gNi (NO
3)
26H
2o is dissolved in 100ml deionized water, the aqueous impregnation step 2 by preparing) in product after roasting, be placed in 100 DEG C of baking ovens dry afterwards, within 2 hours, obtain catalyst C through grinding roasting at 550 DEG C.
Embodiment 4:
A catalyst for toluene direct oxidation producing benzaldehyde, comprises following component: magnesia alumina composite oxide carrier 95wt%, and wherein the mol ratio of magnesia and aluminium oxide is 2, cerium 0.5wt%, cobalt 0.5wt%, copper 2wt%, nickel 2wt%.
The preparation method of above-mentioned catalyst comprises the steps:
1) 39.9gAlCl is taken
3and 28.8gMgCl
2be dissolved in 1200mL deionized water, being mixed with total concentration is 0.5molL
-1mixing salt solution, take 80gNaOH and be dissolved in 400ml deionized water and be mixed with 5molL
-1naOH solution, under agitation NaOH solution is dropwise joined in mixing salt solution, in dropping process, keep system pH 9 ~ 10, NaOH solution dropwises rear continuation and stirs ageing 3 hours, products therefrom is filtered, use deionized water repeatedly to wash 3 times, be placed in 100 DEG C of thermostatic drying chambers dry, be placed in 550 DEG C of Muffle furnace roastings through grinding after drying completes and obtain catalyst carrier in 3 hours;
2) 2.2g (NH is taken
4)
4ce (SO
4)
4and 2.52gCoSO
47H
2o is dissolved in 200mL deionized water, gets 100g step 1) in the catalyst carrier of gained, by (the NH prepared
4)
4ce (SO
4)
4and 2.52gCoSO
47H
2the O aqueous solution is impregnated catalyst support under constantly stirring, after catalyst to be placed in 100 DEG C of baking ovens dry, through grinding roasting 3 hours at 550 DEG C;
3) 6.2gCu (NO is taken
3)
2with 10.4gNi (NO
3)
26H
2o is dissolved in 100ml deionized water, the aqueous impregnation step 2 by preparing) in product after roasting, be placed in 100 DEG C of baking ovens dry afterwards, within 2 hours, obtain catalyst D through grinding roasting at 600 DEG C.
Gained catalyst in embodiment 1-4 is used in the reaction of toluene direct oxidation producing benzaldehyde, reaction is carried out in the reactor of 1.0L, add 50g toluene, 5g catalyst and 500ml acetone as solvent, still closedtop to be closed, mixing speed 800r/min, be heated to 110 DEG C, blowing air reacts, reaction temperature rises to 120 DEG C and controls to react in this temperature, reaction system Stress control is at 5MPa, in 5 hours reaction time, after reaction terminates, reaction system is down to room temperature, open kettle cover, sample analysis.Response data is in table 1.
Table 1: the reactivity data of gained catalyst in embodiment 1-4
The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, within the spirit and principles in the present invention all, any amendment done, equivalent replacement, improvement etc., within the protection domain that all should be included in invention.