CN109876802A

CN109876802A - A kind of catalyst and preparation method thereof preparing glyceric acid for catalysis oxidation glycerol

Info

Publication number: CN109876802A
Application number: CN201910282022.4A
Authority: CN
Inventors: 卫敏; 张俊博; 李晓林; 李印文
Original assignee: Beijing University of Chemical Technology
Current assignee: Beijing University of Chemical Technology
Priority date: 2019-04-09
Filing date: 2019-04-09
Publication date: 2019-06-14

Abstract

The invention discloses a kind of catalyst and preparation method thereof that glyceric acid is prepared for catalysis oxidation glycerol.The carrier of the catalyst is the magnalium hydrotalcite that hydration is restored, and active metal is platinum, load capacity 0.01-2wt%.The catalyst the preparation method comprises the following steps: a) being prepared for catalyst carrier magnalium hydrotalcite using coprecipitation；B) hydrotalcite supports are impregnated with the aqueous solution containing chloroplatinic acid；C) catalyst precarsor obtained is placed in tube furnace, is restored in hydrogen atmosphere；D) catalyst after reduction is directly used into reaction solution fluid-tight, stands reaction, using the memory effect of hydrotalcite, obtain the platinum catalyst for the hydrotalcite load that hydration is restored.The invention provides a kind of simple preparation methods of hydrotalcite loaded catalyst, improve the stability of catalyst, at normal temperatures and pressures can highly selective catalyzing glycerol oxidation glyceric acid processed.

Description

A kind of catalyst and preparation method thereof preparing glyceric acid for catalysis oxidation glycerol

Technical field

The invention belongs to catalyst preparation technical field more particularly to a kind of glyceric acid is prepared for catalysis oxidation glycerol Catalyst and preparation method thereof, the catalyst are specially the magnalium hydrotalcite load platinum catalyst for being hydrated and restoring.

Background technique

With increasingly depleted, the exploitation of sustainable biomass-based resource of the traditional fossil energies such as coal, petroleum, natural gas It gets more and more extensive concerning of people, such as biodiesel.With the rapid development of production of biodiesel, the mistake of by-product glycerin Remaining will be increasingly severe, therefore how to efficiently use a large amount of cheap glycerol and have become problem in the urgent need to address.In crowd In more path for transformation, glycerol is selectively oxidized has broad application prospects in aqueous solution.Glycerol oxidation reaction item Part is mild, can produce a series of fine chemicals of high added values, including glyceraldehyde (GLYD), glyceric acid (GLYA), dihydroxy Benzylacetone (DHA), tartaric acid (TTA), glycolic (GLCOA), oxalic acid (OXA) etc..However, being produced just because of glycerol oxidation reaction Object is numerous, and response path is complicated, how to control its selectivity and then improves the yield of a certain specific product, is glycerol problem of oxidation Key.In addition, since glycerol is highly viscous, higher boiling and not readily dissolved in nonpolar solvent, glycerol oxidation reaction is often It carries out in water, this makes the carriers such as magnesia, aluminium oxide and mixed oxide become unstable, leads to the activity of catalyst It reduces.In the selection of active metal, current research hotspot is concentrated mainly on the noble metal group using Pt, Pd and Au as representative Point.For Au, although its antioxygenic property is better than other two kinds of metals, only when alkali additionally is added in reaction system Just active, this will cause the corrosion of equipment, while be also significantly unfavorable to environmental protection；And for Pd, more It is easy inactivation, is unfavorable for the longtime running of catalysis reaction.And Pt not only has as a kind of industrial most commonly used noble metal Higher activity, and stability is good in glycerol oxidation, not easy in inactivation.

In traditional catalyzing glycerol oxidation loaded catalyst, due to the presence of reaction dissolvent water, oxide carrier holds It is easily rehydrated to become hydroxide, and loaded again if carrier is first hydrated, it will cause Pt (as dried) in operation Nano particle ingress of air and be oxidized, cause the inactivation of catalyst.

Summary of the invention

Aiming at the problem that catalyst easy in inactivation in the preparation of Pt base glycerol oxidation catalyst and reaction process, the present invention is provided A kind of simple method for preparing catalyst, solves vector stabilisation in the inactivation and reaction process of catalyst preparation process Pt The problem of difference, catalyst obtained, which aoxidizes glyceric acid processed to glycerol, higher activity and higher yield.

The carrier of the catalyst of the present invention for preparing glyceric acid for catalysis oxidation glycerol is the magnalium that hydration is restored Hydrotalcite, active metal are platinum, load capacity 0.01-2wt%.

It is of the present invention for catalysis oxidation glycerol prepare glyceric acid catalyst the preparation method comprises the following steps:

1) mixing salt solution of magnesium nitrate and aluminum nitrate is prepared；Prepare the mixed ammonium/alkali solutions of sodium hydroxide and sodium carbonate；

2) mixing salt solution and mixed ammonium/alkali solutions are instilled jointly in the deionized water being stirred continuously, control pH value be 10 ± 0.2, it is warming up to 80-90 DEG C after being added dropwise, aging 12-36 hours, is filtered, washed, is dried to obtain stratiform magnalium hydrotalcite；

3) it will disperse in deionized water after the grinding of stratiform magnalium hydrotalcite, and chloroplatinic acid aqueous solution then be instilled, under room temperature 12-36h is stirred, is finally warming up to 50-65 DEG C, moisture is evaporated completely, product drying, grinding；

4) product for obtaining step 3) is placed in tube furnace, at 300-400 DEG C in hydrogen atmosphere reductase 12-4h, finally Room temperature is down in nitrogen atmosphere；

5) product of step 4) is directly added into fluid-tight in glycerine water solution, is transferred in reactor and stands 0.5-2h, obtained To the catalyst for preparing glyceric acid for catalysis oxidation glycerol, directly logical O under normal temperature and pressure₂Carry out catalysis reaction.

Magnesium ion and aluminum ions molar ratio are 2:1-8:1 in the mixing salt solution of the step 1).

The heating rate of the step 4) is 2 DEG C/min.

The reactor of the step 5) is indirect reaction device.

The concentration of the glycerine water solution is 0.01-1mol/L.

The glycerol and catalyst molar ratio are 800-1200.

The present invention has the advantages that for the first time with the method that hydrated in-situ is restored by the reaction solution liquid of the catalyst after reduction Envelope, avoids Pt nano particle ingress of air and is oxidized；Simultaneously as the memory effect of hydrotalcite, the mixing oxygen after reduction Rehydrated compound carrier is hydrotalcite, improves catalyst in the stability of catalytic reaction process.The present invention not only provides one The new method of kind catalyst preparation, and the application of hydrotalcite loaded catalyst is extended, to new structure catalyst Design has certain directive significance.

Detailed description of the invention

Fig. 1 is the flow diagram for preparing hydration and restoring hydrotalcite supporting Pt.

Fig. 2 is the SEM figure that hydrotalcite is restored in carrier hydration.

Fig. 3 is the TEM figure that hydrotalcite supporting Pt is restored in hydration.

Specific embodiment

[embodiment 1]

1) mixing salt solution of magnesium nitrate and aluminum nitrate is prepared, wherein magnesium ion and aluminum ions molar ratio are respectively 2:1, 4:1,6:1,8:1；Prepare the mixed ammonium/alkali solutions of sodium hydroxide and sodium carbonate；

2) mixing salt solution of 4 ratios is instilled in the deionized water being stirred continuously jointly with mixed ammonium/alkali solutions respectively, Controlling pH value is 10 ± 0.2, and 90 DEG C are warming up to after being added dropwise, aging 24 hours, is filtered, washed, is dried to obtain stratiform magnalium Hydrotalcite；

3) will disperse in deionized water after the grinding of stratiform magnalium hydrotalcite, then chloroplatinic acid is added dropwise in ultrasonic 20min Aqueous solution stirs 12h under room temperature, is finally warming up to 60 DEG C, and moisture is evaporated completely, product drying, grinding；

4) product for obtaining step 3) is placed in tube furnace, restores 3h at 350 DEG C in hydrogen atmosphere, and heating rate is 2 DEG C/min, room temperature is finally down in nitrogen atmosphere；

5) product of step 4) is directly added into fluid-tight in 0.1mol/L glycerine water solution, it is anti-is transferred to indirect type glass tube Answer and stand 1h in device, obtain the catalyst for preparing glyceric acid for catalysis oxidation glycerol, catalyst quality be 39mmg (glycerol with Catalyst molar ratio is that 1000), wherein the load capacity of platinum is 1wt%, directly logical O under last room temperature (30 DEG C) normal pressure₂It is urged Change reaction 12h.Evaluation results are shown in Table 1.

1 glycerol of table aoxidizes glyceric acid performance processed

Claims

1. a kind of catalyst for preparing glyceric acid for catalysis oxidation glycerol, which is characterized in that the carrier of the catalyst is water The magnalium hydrotalcite restored is closed, active metal is platinum, load capacity 0.01-2wt%.

2. the preparation method of the catalyst according to claim 1 for preparing glyceric acid for catalysis oxidation glycerol, feature It is, concrete operation step are as follows:

2) mixing salt solution and mixed ammonium/alkali solutions being instilled jointly in the deionized water being stirred continuously, control pH value is 10 ± 0.2, It is warming up to 80-90 DEG C after being added dropwise, aging 12-36 hours, is filtered, washed, is dried to obtain stratiform magnalium hydrotalcite；

3) it will disperse in deionized water after the grinding of stratiform magnalium hydrotalcite, then instill chloroplatinic acid aqueous solution, stirred under room temperature 12-36h is finally warming up to 50-65 DEG C, and moisture is evaporated completely, product drying, grinding；

4) product for obtaining step 3) is placed in tube furnace, at 300-400 DEG C in hydrogen atmosphere reductase 12-4h, finally in nitrogen Room temperature is down in gas atmosphere；

5) product of step 4) is directly added into fluid-tight in glycerine water solution, is transferred in reactor and stands 0.5-2h, used The catalyst of glyceric acid, directly logical O under normal temperature and pressure are prepared in catalysis oxidation glycerol₂Carry out catalysis reaction.

3. preparation method according to claim 2, which is characterized in that in the mixing salt solution of the step 1) magnesium ion and Aluminum ions molar ratio is 2:1-8:1.

4. preparation method according to claim 2, which is characterized in that the heating rate of the step 4) is 2 DEG C/min.

5. preparation method according to claim 2, which is characterized in that the reactor of the step 5) is indirect reaction Device.

6. preparation method according to claim 2, which is characterized in that the concentration of the glycerine water solution is 0.01-1mol/ L。

7. preparation method according to claim 2, which is characterized in that the glycerol is 800- with catalyst molar ratio 1200。