CN108435171B - Preparation method of bimetallic Pt-Bi catalyst and method for preparing DHA (docosahexaenoic acid) by selectively catalyzing and oxidizing glycerol - Google Patents
Preparation method of bimetallic Pt-Bi catalyst and method for preparing DHA (docosahexaenoic acid) by selectively catalyzing and oxidizing glycerol Download PDFInfo
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Abstract
The invention discloses a preparation method of a bimetallic Pt-Bi catalyst, which comprises the following steps: s1, adding a Pt catalyst into a glycerol reaction liquid containing an auxiliary agent Bi, and catalytically oxidizing glycerol to prepare 1, 3-dihydroxyacetone to obtain a reaction liquid mixture containing a bimetallic Pt-Bi catalyst; s2, separating out the bimetallic Pt-Bi catalyst in the reaction liquid mixture, and then calcining at 200-300 ℃ in an inert atmosphere to prepare the bimetallic Pt-Bi catalyst. The preparation method provided by the invention can prepare the high-activity bimetallic Pt-Bi catalyst by utilizing the inactivated bimetallic Pt-Bi catalyst, and the prepared bimetallic Pt-Bi catalyst has high catalytic activity and can efficiently and selectively catalyze and oxidize glycerin to prepare DHA; the bimetal Pt-Bi catalyst is recycled in the process of selectively catalyzing and oxidizing glycerol to prepare 1, 3-dihydroxyacetone through calcination, the concentration of the glycerol and the content of Bi in a glycerol reaction solution are kept constant, and after 2-6 times of circulation, the bimetal Pt-Bi catalyst can keep DHA selectivity of initial high glycerol conversion rate.
Description
Technical Field
The invention relates to the technical field of glycerin liquid-phase oxidation conversion, in particular to a preparation method of a bimetallic Pt-Bi catalyst and a method for preparing DHA (docosahexaenoic acid) by selectively catalyzing and oxidizing glycerin.
Background
Glycerol is used as a main byproduct in the production process of biodiesel, and has rich sources and very low price. Glycerol is a highly functional molecule, and can be effectively utilized and converted into fine chemical products with high added values, and the method mainly comprises the following steps: glyceraldehyde, 1, 3-Dihydroxyacetone (DHA), glyceric acid, tartaric acid, and the like. Wherein, DHA is widely applied in the fields of cosmetics, foods, pharmacy and the like.
Glycerol has primary and secondary hydroxyl functional groups, and the oxidation reaction is also a structure-sensitive reaction and can be selectively catalyzed and oxidized under certain reaction conditions and the action of a catalyst, so that the oxidation product is very complex.
The Pt catalyst is widely applied to the reaction, single-component Pt can selectively catalyze and oxidize primary hydroxyl of glycerol more easily, and the generated products mainly comprise glyceric acid and glyceraldehyde. The introduction of auxiliary agents Bi, Sb and the like in the Pt catalyst can effectively promote the catalytic oxidation of secondary hydroxyl of glycerol and improve the conversion rate of the glycerol and the selectivity of DHA.
The Pt catalyst can effectively catalyze the oxidation conversion of the glycerol into chemical products with high added values, but the phenomena of poisoning, leaching, sintering and the like exist in the reaction process, so that the Pt catalyst is inactivated, and the conversion rate of the glycerol and the selectivity of the products are greatly reduced.
Therefore, it is required to develop a method for preparing a high-activity bimetallic Pt-Bi catalyst using the deactivated bimetallic Pt-Bi catalyst, which can restore the catalytic activity of the bimetallic Pt-Bi catalyst so that the initial high glycerin conversion rate and DHA selectivity of the bimetallic Pt-Bi catalyst are maintained during the production of 1, 3-dihydroxyacetone.
Disclosure of Invention
The invention provides a preparation method of a bimetallic Pt-Bi catalyst for overcoming the defect of catalyst deactivation in the prior art, and the preparation method can prepare the high-activity bimetallic Pt-Bi catalyst by using the deactivated bimetallic Pt-Bi catalyst.
The invention also aims to provide a method for preparing DHA by selectively catalyzing and oxidizing glycerol, wherein the activity of the bimetallic Pt-Bi catalyst is recovered by calcination after the bimetallic Pt-Bi catalyst is deactivated so as to be recycled, the concentration of the glycerol in the glycerol reaction liquid and the content of the auxiliary agent Bi are kept constant, the initial high glycerol conversion rate and the DHA selectivity can be kept in the recycling process of the bimetallic Pt-Bi catalyst, and the continuous production is realized.
In order to solve the technical problems, the invention adopts the technical scheme that:
a preparation method of a bimetallic Pt-Bi catalyst comprises the following steps:
s1, adding a Pt catalyst into the glycerol reaction liquid containing the auxiliary agent Bi, and catalytically oxidizing the glycerol to prepare 1, 3-dihydroxyacetone to obtain a reaction liquid mixture containing the bimetallic Pt-Bi catalyst;
and S2, separating the bimetallic Pt-Bi catalyst in the reaction liquid mixture, and calcining at 200-300 ℃ in an inert atmosphere to prepare the bimetallic Pt-Bi catalyst.
And S1, generating an in-situ bimetallic Pt-Bi catalyst, wherein the in-situ bimetallic Pt-Bi catalyst is inactivated after the reaction is finished, and the catalytic activity is obviously reduced. The deactivated bimetallic Pt-Bi catalyst is calcined under the conditions to prepare the high-activity bimetallic Pt-Bi catalyst, and the prepared bimetallic Pt-Bi catalyst has high catalytic activity and can efficiently and selectively catalyze and oxidize glycerin to prepare DHA.
When the temperature is lower than 200 ℃, the catalytic activity of the deactivated bimetallic Pt-Bi catalyst after calcination is not very desirable because the temperature is too low to facilitate the shedding of strongly adsorbed intermediate substances. When the temperature is too high, agglomeration of the noble metal Pt nanoparticles is caused, and active sites are reduced.
Moreover, the preparation method is simple, easy to operate and suitable for industrial popularization and use.
Preferably, the preparation method further comprises the following steps:
s3, adding the bimetallic Pt-Bi catalyst prepared in the step S2 into the glycerol reaction liquid containing the auxiliary agent Bi, and catalytically oxidizing the glycerol to prepare 1, 3-dihydroxyacetone to obtain a reaction liquid mixture containing the bimetallic Pt-Bi catalyst; and separating the bimetallic Pt-Bi catalyst in the reaction liquid mixture, and calcining at 200-300 ℃ in an inert atmosphere to prepare the bimetallic Pt-Bi catalyst.
Adding the prepared bimetallic Pt-Bi catalyst into a glycerin reaction liquid containing an auxiliary agent Bi, and performing the steps S1 and S2 again to obtain the bimetallic Pt-Bi catalyst calcined twice;
preferably, the step S3 is performed circularly, and the number of times of performing the step S3 is 1-4.
And (4) circularly performing the step S3. so that the bimetallic Pt-Bi catalyst which is calcined for multiple times can be prepared.
Preferably, step s3. is performed 2 times.
The inert atmosphere comprises Ar atmosphere and N2An atmosphere.
Preferably, the inert atmosphere is argon atmosphere, and the flow rate of argon is 10-200 mL/min. The argon atmosphere was achieved by passing argon.
More preferably, the flow rate of the argon is 20-150 mL/min.
Further preferably, the flow rate of argon is 100 mL/min.
Preferably, the calcining time is 0.5-4 h.
More preferably, the calcination time is 2 h.
Preferably, Bi in the glycerol reaction liquid is one or more of bismuth oxide, bismuth chloride and bismuth nitrate.
Preferably, the mass of the auxiliary agent Bi in the glycerol reaction liquid is 10% -100% of the mass of Pt.
Preferably, the mass of the auxiliary agent Bi in the glycerol reaction liquid is 20-50% of the mass of Pt.
More preferably, the mass of the auxiliary agent Bi in the glycerin reaction liquid is 20% of the mass of Pt.
Preferably, the support of the Pt catalyst is a nitrogen-doped carbon material.
Preferably, the nitrogen-doped carbon material is one or more of nitrogen-doped carbon nanotubes, carbon nanofibers or graphene.
Preferably, the loading amount of Pt in the Pt catalyst is 2-10 wt.%.
Preferably, the loading of Pt in the Pt catalyst is 5 wt.%.
Preferably, in S1, the conditions for preparing 1, 3-dihydroxyacetone by catalytic oxidation of glycerol are as follows: glycerin quality of glycerin reaction liquidThe content is 1-10 wt.%, the reaction temperature is 50-80 ℃, and O is2The flow rate is 10-200 mL/min, the stirring speed is 100-800 r/min, and the reaction time is 1-10 h.
More preferably, the oxidation reaction conditions of s1 are: the glycerol mass content of the glycerol reaction liquid is 1-10 wt.%, the reaction temperature is 60-80 ℃, and O is2The flow rate is 50-150 mL/min, the stirring speed is 400-600 r/min, and the reaction time is 2-6 h.
Further preferably, the oxidation reaction conditions of s1 are: the glycerol mass content of the glycerol reaction solution is 10wt.%, the reaction temperature is 60 ℃, and O is2The flow rate is 150mL/min, the stirring speed is 600 r/min, and the reaction time is 6 h.
Preferably, the solvent of the glycerol reaction solution is water.
The invention also provides a method for preparing DHA by selectively catalyzing and oxidizing glycerol, which comprises the following steps:
s1, adding a Pt catalyst into the glycerol reaction liquid containing the auxiliary agent Bi, and catalytically oxidizing the glycerol to prepare 1, 3-dihydroxyacetone to obtain a reaction liquid mixture containing the bimetallic Pt-Bi catalyst;
s2, separating the bimetallic Pt-Bi catalyst in the reaction liquid mixture, and then calcining at 200-300 ℃ in an inert atmosphere to prepare the bimetallic Pt-Bi catalyst;
s3, adding the bimetallic Pt-Bi catalyst prepared in the step S2 into a glycerin reaction liquid containing an auxiliary agent Bi, and catalytically oxidizing glycerin to prepare 1, 3-dihydroxyacetone to obtain a reaction liquid mixture containing the bimetallic Pt-Bi catalyst; then, carrying out step S2. to prepare the bimetallic Pt-Bi catalyst again;
s4, circularly performing the step S3, wherein the performing time of the step S3 is 1-5 times, and the concentration of the glycerol and the content of the auxiliary agent Bi in the glycerol reaction liquid are kept constant; the continuous production of 1, 3-dihydroxyacetone is achieved during the performance of step S1 and the recycling of step S3.
The production method provided by the invention adopts the in-situ bimetallic Pt-Bi catalyst to selectively catalyze and oxidize the glycerol to prepare the 1, 3-dihydroxyacetone, the in-situ bimetallic Pt-Bi catalyst has high catalytic activity, and the DHA selectivity of the glycerol conversion rate is high; the reacted bimetallic Pt-Bi catalyst is inactivated, the inactivated bimetallic Pt-Bi catalyst is regenerated by the calcining method, the catalytic activity of the bimetallic Pt-Bi catalyst is recovered, the recycling of the bimetallic Pt-Bi catalyst is realized, the glycerol concentration and the auxiliary agent Bi content in the glycerol reaction liquid are kept constant, and the bimetallic Pt-Bi catalyst can keep the DHA selectivity of initial high glycerol conversion rate, so that the industrial continuous production is realized.
Compared with the prior art, the invention has the beneficial effects that:
the preparation method provided by the invention can be used for preparing the high-activity bimetallic Pt-Bi catalyst by utilizing the inactivated bimetallic Pt-Bi catalyst, and the prepared bimetallic Pt-Bi catalyst has high catalytic activity and can be used for efficiently and selectively catalyzing and oxidizing glycerol to prepare DHA.
In addition, the method for preparing 1, 3-dihydroxyacetone by selectively catalyzing and oxidizing glycerol, provided by the invention, regenerates the inactivated bimetallic Pt-Bi catalyst by calcining, so that the bimetallic Pt-Bi catalyst is recycled, the concentration of glycerol and the content of the auxiliary agent Bi in the glycerol reaction solution are kept constant, and the bimetallic Pt-Bi catalyst can keep the DHA selectivity of initial high glycerol conversion rate, thereby realizing industrial continuous production.
Detailed Description
The present invention will be further described with reference to the following embodiments.
The raw materials in the examples are all commercially available;
reagents, methods and apparatus used in the present invention are conventional in the art unless otherwise indicated.
The Pt catalysts in the examples and comparative examples were prepared as follows:
pouring 100 mg of nitrogen-doped carbon material into 60 ml of ethylene glycol solution to obtain nitrogen-doped carbon material dispersion liquid, and performing ultrasonic dispersion for 20 min; then 1.35 mL of H2PtCl6 (0.02M) the solution was added to the nitrogen-doped carbon material dispersion; adjusting pH to 8.5 with 0.04M KOH solution, stirring and refluxing at 140 deg.C for 2 h; cooling to room temperature, filtering, leaching until the filtrate is neutral, vacuum drying at 75 ℃ for 24 h, grinding to obtain a fresh Pt catalystPt loading of 5 wt.%.
Example 1
(1) Preparation of 1, 3-dihydroxyacetone by catalytic oxidation of glycerol
Into a 150mL four-necked flask was added an aqueous glycerol solution (50 g, 10wt.%, Bi (m)Bi / mPt= 0.2)) and 100 mg of Pt catalyst, the in-situ bimetallic Pt-Bi catalyst is formed, the temperature is raised to 60 ℃ at the stirring speed of 600 rpm, then oxygen (150 mL/min) is introduced, and the reaction is started; after 6h, the reaction was stopped. Weighing the mixture of the reaction solution and the catalyst in the reactor before and after the reaction, and filtering the liquid-solid phase mixture; the reaction solution was analyzed by liquid chromatography.
(2) Regeneration of bimetallic Pt-Bi catalysts
Filtering the bimetallic Pt-Bi catalyst reacted in the step (1), washing with water and alcohol, drying in vacuum, grinding, loading into a porcelain boat, and calcining in a horizontal high-temperature tube furnace under the conditions of 200 ℃ of temperature, 100mL/min of Ar flow and 2h of calcining time; the resulting catalyst was labeled Pt-Bi (200).
Example 2
The present example is different from example 1 in that the temperature of calcination in (2) is 300 ℃; the rest is the same as the embodiment 1; the resulting catalyst was labeled Pt-Bi (300).
Example 3
The Pt-Bi (300) prepared in example 2 was recycled once, i.e., steps (1) and (2) were repeated, and the resulting catalyst was labeled as Pt-Bi (300-2).
Example 4
The Pt-Bi (300-2) prepared in example 3 was recycled once, i.e., steps (1) and (2) were repeated, and the resulting catalyst was labeled as Pt-Bi (300-3).
Example 5
The Pt-Bi (300-3) prepared in example 4 was recycled once, i.e., steps (1) and (2) were repeated, and the resulting catalyst was labeled as Pt-Bi (300-4).
Comparative example 1
(1) Preparation of 1, 3-dihydroxyacetone by catalytic oxidation of glycerol
Into a 150mL four-necked flask, an aqueous glycerol solution (50 g, 10wt.%) and 100 mg of Pt catalyst were added, and the temperature was raised to 60 ℃ at a stirring rate of 600 rpm, followed by introduction of oxygen (150 mL/min) to start a reaction; after 6h, the reaction was stopped. Weighing the mixture of the reaction solution and the catalyst in the reactor before and after the reaction, and filtering the liquid-solid phase mixture; the reaction solution was analyzed by liquid chromatography.
(2) Separation of Pt catalyst
The Pt catalyst reacted in (1) was filtered, washed with water and alcohol, dried under vacuum, and then ground, and the catalyst obtained was designated as Pt (2).
Comparative example 2
(1) Preparation of 1, 3-dihydroxyacetone by catalytic oxidation of glycerol
Into a 150mL four-necked flask was added an aqueous glycerol solution (50 g, 10wt.%, Bi (m)Bi / mPt= 0.2)) and 100 mg of Pt catalyst, the in-situ bimetallic Pt-Bi catalyst is formed, the temperature is raised to 60 ℃ at the stirring speed of 600 rpm, then oxygen (150 mL/min) is introduced, and the reaction is started; after 6h, the reaction was stopped. Weighing the mixture of the reaction solution and the catalyst in the reactor before and after the reaction, and filtering the liquid-solid phase mixture; the reaction solution was analyzed by liquid chromatography.
(2) Separation of bimetallic Pt-Bi catalysts
Filtering the bimetallic Pt-Bi catalyst reacted in the step (1), washing with water and alcohol, drying in vacuum, and grinding to obtain the catalyst Pt-Bi (2).
Comparative example 3
The present comparative example differs from comparative example 2 in that (2) the procedure of separation of the bimetallic Pt-Bi catalyst is as follows: adding acetone (100 mg/200 mL) into the bimetallic Pt-Bi catalyst reacted in the step (1), stirring for 2h at 60 ℃, filtering and washing by using alcohol at 80 ℃, drying in vacuum and grinding; the others are the same as in comparative example 2;
the resulting catalyst was labeled Pt-Bi (Ace.).
Comparative example 4
The present comparative example differs from comparative example 2 in that (2) the procedure of separation of the bimetallic Pt-Bi catalyst is as follows: adding 1M NaOH (100 mg/200 mL) into the bimetallic Pt-Bi catalyst reacted in the step (1), stirring at room temperature for 2h, and pouring out the alkali liquor; adding acetone solution (100 mg/200 mL), stirring at 60 deg.C for 1 h, filtering with 80 deg.C alcohol, washing, vacuum drying, and grinding; the others are the same as in comparative example 2;
the resulting catalyst was labeled Pt-Bi (OH).
Comparative example 5
This comparative example is different from example 1 in that the temperature of calcination in (2) is 150 ℃; the rest is the same as the embodiment 1; the resulting catalyst was labeled Pt-Bi (150).
Performance testing
And carrying out qualitative and quantitative analysis on the reaction liquid by adopting a high performance liquid chromatography provided with an ultraviolet and differential detector. HPX-87H (Aminex) as a separation column, H2SO4(0.025M) as the mobile phase. The wavelength of the ultraviolet detector is set to 210 nm, the temperature of the differential detector is 40 ℃, the column temperature is 60 ℃, and the flow phase rate is 0.6 mL/min-1. In the research, qualitative analysis is carried out according to a standard sample, and both reactants and products are subjected to quantitative analysis by an external standard method.
The method for calculating the glycerol conversion rate and the DHA selectivity of the catalyst is as follows:
(1) conversion of Glycerol
Glycerol conversion (%) = (mass of glycerol before reaction-mass of glycerol remaining after reaction)/mass of glycerol before reaction × 100%
(2) DHA selectivity
DHA selectivity (%) = mass of DHA produced by reaction X92/[ (mass of glycerin before reaction-mass of glycerin remaining after reaction) × 90] × 100%
In examples 1-5 and comparative examples 2-5, the catalyst for the first reaction was denoted as Pt-Bi, i.e., an initial in-situ bimetallic Pt-Bi catalyst;
in comparative example 1, the catalyst of the first reaction was noted as Pt, i.e., the initial Pt catalyst.
The catalytic performance of the catalysts prepared in examples 1 to 5 is shown in table 1;
the catalytic performance of the catalysts prepared in comparative examples 1 to 5 is shown in table 2.
TABLE 1 catalytic Performance of catalysts prepared in examples 1 to 5
TABLE 2 catalytic performance of catalysts prepared in comparative examples 1 to 5
As can be seen from Table 1, the bimetallic Pt-Bi catalyst prepared by the preparation method provided by the invention has high catalytic activity and can efficiently and selectively catalyze and oxidize glycerin to prepare DHA. The glycerol conversion rate and the DHA selectivity of the catalysts obtained in the embodiments 1-5 are 25.2% -31.1% and 52.9% -62.6%, respectively, and the glycerol conversion rate and the DHA selectivity of the initial in-situ bimetallic Pt-Bi catalyst are 18.0% and 44.7%, respectively, so that the catalytic performance of the bimetallic Pt-Bi catalyst prepared in the embodiments 1-5 is obviously superior to that of the initial in-situ bimetallic Pt-Bi catalyst. Therefore, the method provided by the invention not only recovers the catalytic activity of the bimetallic Pt-Bi catalyst, but also improves the catalytic activity of the bimetallic Pt-Bi catalyst. Among these, example 3 has the best catalytic effect, with 1.73 times the glycerol conversion of the initial in situ bimetallic Pt-Bi catalyst. DHA selectivity generally decreases to some extent with increasing conversion. Example 3 at higher glycerol conversion, DHA selectivity was still 1.30 times that of the initial in situ bimetallic Pt-Bi catalyst.
From examples 2 to 5, it can be seen that the method for preparing 1, 3-dihydroxyacetone by selective catalytic oxidation of glycerol provided by the invention can realize industrial continuous production by maintaining the initial high glycerol conversion rate and the DHA selectivity by recycling the bimetallic Pt-Bi catalyst, keeping the glycerol concentration and the auxiliary Bi content in the glycerol reaction solution constant. Moreover, after 4 regenerations, i.e. at cycle 5, the bimetallic Pt-Bi catalyst still has high catalytic activity, and can maintain initial high glycerol conversion rate and DHA selectivity.
As mentioned above, the introduction of the promoter Bi in the Pt catalyst, i.e., the in-situ bimetallic Pt-Bi catalyst, can improve the glycerol conversion rate and DHA selectivity, as shown in table 2.
The bimetallic Pt-Bi catalysts obtained in the comparative examples 2-5 have low catalytic activity, and the initial high glycerol conversion rate and the DHA selectivity are difficult to maintain. The bimetallic Pt-Bi catalyst reacted in the comparative example 2 is not calcined and regenerated, and the glycerol conversion rate and the DHA selectivity are obviously reduced. The acetone treatment is adopted in the comparative example 3, the NaOH aqueous solution treatment is adopted in the comparative example 4, the calcination regeneration is not carried out, and the glycerin conversion rate and the DHA selectivity are also obviously reduced. In comparative example 5, although calcination regeneration was used, the temperature was low and it was difficult to maintain the initial high glycerol conversion and DHA selectivity for the regenerated bimetallic Pt-Bi catalyst.
It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.
Claims (9)
1. A preparation method of a bimetallic Pt-Bi catalyst is characterized by comprising the following steps:
s1, adding a Pt catalyst into a glycerol reaction liquid containing an auxiliary agent Bi, and catalytically oxidizing glycerol to prepare 1, 3-dihydroxyacetone to obtain a reaction liquid mixture containing a bimetallic Pt-Bi catalyst;
s2, separating out the bimetallic Pt-Bi catalyst in the reaction liquid mixture, and then calcining at 200-300 ℃ in an inert atmosphere to prepare the bimetallic Pt-Bi catalyst;
the calcining time is 0.5-4 h;
the mass of the auxiliary agent Bi in the glycerol reaction liquid is 20-50% of the mass of Pt.
2. The method of claim 1, further comprising the steps of:
s3, adding the bimetallic Pt-Bi catalyst prepared in the step S2 into the glycerol reaction liquid containing the auxiliary agent Bi, and catalytically oxidizing the glycerol to prepare 1, 3-dihydroxyacetone to obtain a reaction liquid mixture containing the bimetallic Pt-Bi catalyst; and separating the bimetallic Pt-Bi catalyst in the reaction liquid mixture, calcining at 200-300 ℃ in an inert atmosphere, and preparing the bimetallic Pt-Bi catalyst again.
3. The preparation method according to claim 2, wherein the step S3 is performed in a cycle, and the number of times of performing the step S3 is 1-4.
4. The method according to claim 3, wherein step S3. is carried out 2 times.
5. The method according to claim 1, wherein the inert atmosphere is an argon atmosphere, and the flow rate of argon is 10 to 200 mL/min.
6. The method according to claim 5, wherein the flow rate of the argon gas is 20 to 150 mL/min.
7. The method according to claim 1, wherein the calcination is carried out for a period of 2 hours.
8. The method of claim 1, wherein the support of the Pt catalyst is a nitrogen-doped carbon material.
9. A method for preparing DHA by selectively catalyzing and oxidizing glycerol is characterized by comprising the following steps:
s1, adding a Pt catalyst into a glycerol reaction liquid containing an auxiliary agent Bi, and catalytically oxidizing glycerol to prepare 1, 3-dihydroxyacetone to obtain a reaction liquid mixture containing a bimetallic Pt-Bi catalyst;
s2, separating out the bimetallic Pt-Bi catalyst in the reaction liquid mixture, and then calcining at 200-300 ℃ in an inert atmosphere to prepare the bimetallic Pt-Bi catalyst;
s3, adding the bimetallic Pt-Bi catalyst prepared in the step S2 into a glycerin reaction liquid containing an auxiliary agent Bi, and catalytically oxidizing glycerin to prepare 1, 3-dihydroxyacetone to obtain a reaction liquid mixture containing the bimetallic Pt-Bi catalyst;
then, carrying out step S2. to prepare the bimetallic Pt-Bi catalyst again;
s4, circularly performing the step S3, wherein the performing time of the step S3 is 1-5 times, and the concentration of the glycerol and the content of the auxiliary agent Bi in the glycerol reaction liquid are kept constant; the continuous production of 1, 3-dihydroxyacetone is achieved during the performance of step S1 and the recycling of step S3.
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