A method for preparing hydroxyacetone by catalytic conversion of enteromorpha and its derivatives - rhamnose, glucose and xylose

Abstract

A method for preparing hydroxyacetone by catalytic conversion of Enteromorpha and its derivatives rhamnose, glucose, and xylose. First, a Pd-based catalyst supported on different supports (γ-Al2O3, MgO, hydrotalcite, TiO2, and ZrO2) was designed and prepared using an impregnation-freeze-drying method. Hydroxyacetone was prepared in an autoclave under a hydrogen atmosphere using Enteromorpha and its derivatives rhamnose, glucose, and xylose as raw materials and water as the reaction solvent. The Pd / γ-Al2O3 catalyst exhibited the best catalytic activity. Under the optimal reaction conditions, the carbon molar yields of hydroxyacetone obtained using Enteromorpha and rhamnose as raw materials were 45.9% and 62.2%, respectively.

Description

Technical Field

[0001] The present invention relates to the preparation of a catalyst for efficiently catalyzing the conversion of Enteromorpha and its derivatives, rhamnose, glucose and xylose, to prepare hydroxyacetone, and a method for catalyzing the conversion of Enteromorpha and its derivatives, rhamnose, glucose and xylose to prepare hydroxyacetone. Background Art

[0002] Hydroxyacetone (1-hydroxy-2-propanone) is a non-toxic and harmless chemical. Due to its two functional groups, hydroxyl and carbonyl, it is highly reactive and can undergo reactions such as oxidation, polymerization, and dehydration. It is an important chemical intermediate and raw material for organic synthesis. It is widely used in catalytic steam hydrogen production, in the textile industry to fix dyes, as a skin tanning agent, as a green solvent, a flavoring agent, and as an intermediate in fine chemicals and pharmaceuticals. For example, in the food industry, hydroxyacetone can impart a flavor that is almost identical to proline, valine, and isoleucine, making it a common ingredient in bread flavorings. In the textile industry, hydroxyacetone can replace sodium bisulfite in the reduction of dyes to produce water-soluble compounds. Furthermore, in the cosmetics industry, hydroxyacetone is a primary ingredient in skin tanning agents.

[0003] The traditional production methods of hydroxyacetone mainly include chemical synthesis and microbial methods: (1) bromoacetone reacts with sodium (potassium) formate and then hydrolyzes in methanol; (2) direct oxidation of acetone using Bayer-Villiger reagent; (3) palladium-catalyzed dehydrogenation of 1,2-propylene glycol in the presence of hydrogen peroxide; (4) biosynthesis-microbial metabolic engineering. Due to the low production efficiency and long reaction cycle of traditional chemical synthesis and microbial methods, it is of great significance to develop a new chemical catalytic method to prepare hydroxyacetone. At present, the chemical catalytic method for preparing hydroxyacetone mainly focuses on the dehydration reaction of glycerol in fixed bed or continuous reactors. However, there are only a few reports on the preparation of hydroxyacetone using renewable biomass resources. For example, Ni-SnO x / Al2O3 was used as a catalyst to convert cellulose and glucose in a high-temperature reactor, and the yields of hydroxyacetone were 35% and 53%, respectively (J.Mol.Catal.A, 2014, 388-399, 66-73); using Ni-Sn / SiO2 and Co-Sn / SiO2 as catalysts, the yields of hydroxyacetone produced from cellulose by catalytic conversion reached 61.6% and 54.4%, respectively (Green Chem., 2019, 21, 5647-5656; Green Chem., 2020, 22, 6579-6587); using RuSn / SiO2 as a catalyst, hydroxyacetone was obtained from cellulose with a yield of 53.7% (J.Energy Chem., 2022, 73, 607-614). However, the catalysts reported in the studies are all bimetallic catalysts containing Sn, which have complex structures. Not only is the preparation process cumbersome, but it is also difficult to directly use them for the catalytic conversion of native biomass to produce hydroxyacetone.

[0004] Based on the above research, it is shown that it is of great significance to develop a high-performance, low-cost catalyst to directly prepare hydroxyacetone from native biomass. Enteromorpha is a kind of algae waste rich in sugar, mainly containing rhamnose (~18.1wt%), glucose (~13.5wt%), xylose (~8.2wt%), etc. In recent years, it has continued to erupt in the Yellow Sea area of ​​my country, not only causing environmental pollution, but also a waste of resources. The effective conversion of Enteromorpha into high-value chemicals, turning Enteromorpha into "waste into treasure", is of great significance to the sustainable development of human society.

[0005] In view of this, the present invention uses cheap rhamnose as the reaction raw material, designs palladium-based catalysts (Pd / γ-Al2O3, Pd / MgO, Pd / HT, Pd / TiO2, Pd / ZrO2) loaded with different carriers (γ-Al2O3, MgO, hydrotalcite, TiO2, ZrO2), uses water as the solvent, and obtains hydroxyacetone in high yield and high selectivity under a hydrogen atmosphere. At the same time, the catalyst is used to catalyze the conversion of Enteromorpha to produce hydroxyacetone, which can obtain a high yield of hydroxyacetone. After the reaction, the solid catalyst can be separated by vacuum filtration, facilitating the purification of the product and the reuse of the catalyst. Summary of the Invention

[0006] The present invention designs and prepares Pd-based catalysts with different supports (γ-Al2O3, MgO, hydrotalcite, TiO2, ZrO2) for the catalytic conversion of Enteromorpha and its derivatives, rhamnose, glucose, and xylose, to produce hydroxyacetone. Pd / γ-Al2O3 exhibits the best catalytic activity. The catalyst is simple, easy to prepare, and low-cost; it also has high catalytic efficiency, and the yield of hydroxyacetone obtained is high. Furthermore, after the reaction, the catalyst can be recovered by simple filtration, resulting in a high reusability. This method overcomes the limitations of previous chemical catalysis methods that use complex Sn-containing bimetallic catalysts, as well as the low production efficiency and high cost of traditional chemical synthesis and microbial methods. This method can also be applied to the catalytic conversion of Enteromorpha, expanding the substrate to native biomass.

[0007] Key points of the invention: Pd precursor and surfactant PVP (K30) were added to 5 mL of water and ultrasonicated for 15 minutes to dissolve and disperse the active components. The carrier was then added and stirred for 4 hours. After immersion for 24 hours, the water was removed by freeze-drying and dried at 80°C for 10 hours. The dried solid was ground and placed in a muffle furnace, calcined at 500°C for 3 hours (heating rate 5°C / min), and the resulting solid was reduced at 450°C under a H2 atmosphere (40 mL / min) for 2 hours to obtain a Pd-based catalyst.

[0008] Taking Pd / γ-Al2O3 catalyst as an example, 100 mg of rhamnose and the Pd / γ-Al2O3 catalyst prepared according to the above method were added to 50 mL of water and heated in a closed autoclave under a hydrogen atmosphere. The catalyst loading was 1 to 10 wt%, the reaction temperature was 50 to 250 ° C, the reaction time was 1 to 180 min, the catalyst dosage was 50 to 200 mg, and the initial hydrogen pressure was 0.5 to 5 MPa. After the reaction, the reactor was cooled to room temperature, and the solid catalyst was separated and recovered by filtration under reduced pressure. It was placed in an oven at 80 ° C for 10 hours, and then placed in a muffle furnace for calcination at 500 ° C for 3 hours. It was reduced at 450 ° C under a H2 atmosphere (40 mL / min) for 2 hours and used for the next catalytic reaction. The small molecule products in the filtered reaction solution were detected by HPLC.

[0009] In the present invention, the catalyst loading is selected to be 1 to 10 wt%. When the palladium loading is less than 1 wt%, the rhamnose conversion rate and hydroxyacetone yield are both low; while when the catalyst loading exceeds 10 wt%, the rhamnose conversion rate and hydroxyacetone yield do not change significantly with increasing catalyst loading.

[0010] In the present invention, the reaction temperature is selected to be 50-250°C. At a lower reaction temperature, rhamnose mainly undergoes hydrogenation to form rhamnitol; as the reaction temperature increases, the yield of hydroxyacetone increases and the yield of rhamnitol decreases; and when the reaction temperature exceeds 250°C, the yield of hydroxyacetone decreases.

[0011] In the present invention, the reaction time is selected to be 1 to 180 minutes. If the reaction temperature is stopped within 1 minute of reaching the target temperature, the conversion of rhamnose is incomplete and the yield of hydroxyacetone is low. When the reaction time exceeds 180 minutes, the yield of hydroxyacetone decreases slightly.

[0012] In the present invention, the amount of catalyst used is 50 to 200 mg. When the amount of catalyst used is less than 50 mg, the rhamnose conversion rate and hydroxyacetone yield are both low; when the amount of catalyst used exceeds 200 mg, the rhamnose conversion rate and hydroxyacetone yield decrease as the amount of catalyst used increases.

[0013] In the present invention, the initial hydrogen pressure is selected to be 0.5-5 MPa. When the hydrogen pressure is lower than 0.5 MPa, the rhamnose conversion rate and the hydroxypyruvic acid yield are low; when the hydrogen pressure is greater than 5 MPa, the hydroxyacetone yield decreases and the rhamnitol yield increases sharply.

[0014] The catalytic system of the present invention is also suitable for catalytic conversion of glucose, xylose and enteromorpha to prepare hydroxyacetone. DETAILED DESCRIPTION

[0015] Example 1-5:

[0016] 1) In a 100 mL autoclave, 100 mg of rhamnose and 100 mg of a Pd-based catalyst (Pd loading in the catalyst is 3 wt%) were added, followed by 50 mL of deionized water. The autoclave was sealed, and hydrogen was introduced to maintain a pressure of 2 MPa. The temperature was raised to 180° C. with stirring, and the reaction was carried out for 120 minutes. The autoclave was then removed from the heating device and naturally cooled to room temperature. The autoclave was opened, and the solid-liquid mixture within the autoclave was separated by vacuum filtration to obtain a solid residue and a product mixture.

[0017] 2) The collected solid residue was washed three times with deionized water, placed in an oven, dried, and then calcined in a muffle furnace at 500°C for 3 h. It was then reduced at 450°C under a H2 atmosphere (40 mL / min) for 2 h and used for the next catalytic reaction. The small molecule product in the reaction solution was analyzed by HPLC, and the results are shown in Table 1 (yields in the table are molar carbon yields, where product yield = molar carbon content of the product obtained / molar carbon content of the starting material added × 100%).

[0018] Table 1

[0019] Implementation Cases catalyst Conversion rate Rhamnitol 1,3-Dihydroxyacetone lactic acid Hydroxyacetone 1 <![CDATA[3-Pd / γ-Al2O3]]> 96.5％ 4.0％ 4.6％ <0.1％ 62.2％ 2 3-Pd / MgO 98.1％ 1.0％ 5.7％ 5.7％ 55.1％ 3 3-Pd / hydrotalcite 99.0％ 1.1％ 5.5％ 3.6％ 49.1％ 4 <![CDATA[3-Pd / TiO2]]> 72.6％ 3.8％ 3.0％ 3.2％ 33.6％ 5 <![CDATA[3-Pd / ZrO2]]> 74.2％ 4.6％ 5.4％ <0.1％ 34.9％

[0020] Examples 6-8:

[0021] The experimental steps are the same as those in Example 1, except that the Pd loading in the selected Pd / γ-Al2O3 catalyst is different. Other conditions remain unchanged. The specific results are listed in Table 2 (the yield in the table is the carbon molar yield).

[0022] Table 2

[0023] Implementation Cases Pd loading Conversion rate Rhamnitol 1,3-Dihydroxyacetone lactic acid Hydroxyacetone 6 1wt% 93.7％ 2.0％ 4.3％ <0.1％ 52.7％ 7 2wt% 95.0％ 2.9％ 4.6％ <0.1％ 55.6％ 8 5wt% 97.5％ 6.2％ 4.1％ <0.1％ 62.5％

[0024] Examples 9-12:

[0025] The experimental steps are the same as those in Example 1, except that the reaction temperature is different. Other conditions remain unchanged. The specific results are listed in Table 3 (the yield in the table is the carbon molar yield).

[0026] Table 3

[0027] Implementation Cases Reaction temperature Conversion rate Rhamnitol 1,3-Dihydroxyacetone lactic acid Hydroxyacetone 9 160℃ 72.5％ 12.6％ 5.2％ <0.1％ 32.6％ 10 170℃ 84.6％ 5.2％ 4.7％ <0.1％ 48.0％ 11 190℃ 99.0％ 3.9％ 4.1％ <0.1％ 60.8％ 12 200℃ 99.9％ 2.2％ 3.6％ <0.1％ 50.4％

[0028] Examples 13-17:

[0029] The experimental steps are the same as those in Example 1, except that the reaction time is different. Other conditions remain unchanged. The specific results are listed in Table 4 (the yield in the table is the molar yield of carbon).

[0030] Table 4

[0031] Implementation Cases Reaction time Conversion rate Rhamnitol 1,3-Dihydroxyacetone lactic acid Hydroxyacetone 13 1min 34.5％ 2.6％ 2.2％ <0.1％ 12.6％ 14 30min 65.3％ 3.0％ 7.1％ <0.1％ 34.8％ 15 60min 83.9％ 3.9％ 5.1％ <0.1％ 46.1％ 16 90 minutes 88.6％ 3.8％ 4.9％ <0.1％ 54.3％ 17 150min 98.0％ 3.9％ 3.9％ <0.1％ 58.1％

[0032] Examples 18-21:

[0033] The experimental steps are the same as those in Example 1, except that the amount of catalyst used is different. Other conditions remain unchanged. The specific results are listed in Table 5 (the yield in the table is the carbon molar yield).

[0034] Table 5

[0035] Implementation Cases Catalyst dosage Conversion rate Rhamnitol 1,3-Dihydroxyacetone lactic acid Hydroxyacetone 18 50mg 88.3％ 2.9％ 5.3％ <0.1％ 48.1％ 19 75mg 91.6％ 3.4％ 5.0％ <0.1％ 55.7％ 20 125mg 98.1％ 5.4％ 4.5％ <0.1％ 59.8％ 21 150mg 99.3％ 6.6％ 4.4％ <0.1％ 58.6％

[0036] Examples 22-25:

[0037] The experimental steps were the same as those in Example 1, except that the hydrogen pressure was different (when the hydrogen pressure was 0, 2 MPaN2 was used instead). Other conditions remained unchanged. The specific results are listed in Table 6 (the yield in the table is the carbon molar yield).

[0038] Table 6

[0039] Implementation Cases <![CDATA[H2 pressure]]> Conversion rate Rhamnitol 1,3-Dihydroxyacetone lactic acid Hydroxyacetone 22 0 90.1％ <0.1％ 5.5％ <0.1％ 25.5％ 23 1MPa 96.0％ 3.5％ 4.5％ <0.1％ 54.6％ 24 3MPa 97.4％ 18.6％ 4.2％ <0.1％ 43.8％ 25 4MPa 98.6％ 36.8％ 4.0％ <0.1％ 27.4％

[0040] Examples 26-29:

[0041] The experimental procedure is the same as that of Example 1, except that the catalyst was reused a different number of times. Other conditions remained unchanged. The specific results are listed in Table 7 (the yield in the table is the carbon molar yield).

[0042] Table 7

[0043] Implementation Cases Number of cycles Conversion rate Rhamnitol 1,3-Dihydroxyacetone lactic acid Hydroxyacetone 26 1 96.0％ 3.8％ 4.4％ <0.1％ 61.8％ 27 2 95.4％ 3.8％ 4.1％ <0.1％ 61.2％ 28 3 94.2％ 3.6％ 3.8％ <0.1％ 60.5％ 29 4 93.1％ 3.4％ 3.7％ <0.1％ 59.0％

[0044] Examples 30-32:

[0045] The experimental steps were the same as those in Example 1, except that different reaction substrates were used. Enteromorpha was hydrolyzed with oxalic acid and then purified before use in the reaction. Other conditions remained unchanged. The specific results are listed in Table 8 (the yield in the table is the carbon molar yield).

[0046] Table 8

[0047] Implementation Cases Reaction substrate Conversion rate Hydroxyacetone 30 glucose 99.8％ 42.6％ 31 Xylose 99.8％ 33.2％ 32 Enteromorpha - 45.9％

Claims

1. A method for preparing hydroxyacetone by catalytic conversion of enteromorpha, rhamnose, glucose and xylose, characterized in that A Pd / γ-Al2O3 catalyst was designed and prepared using an impregnation-freeze-drying method for subsequent catalytic reactions. Hydroxyacetone was prepared in a sealed autoclave under a hydrogen atmosphere using Enteromorpha, rhamnose, glucose, and xylose as raw materials and water as solvent. The substrate dosage was 100 mg, the palladium loading on the catalyst was 1-10 wt%, the reaction temperature was 50-250°C, the reaction time was 1-180 minutes, the catalyst dosage was 50-200 mg, and the initial hydrogen pressure was 0.5-5 MPa. When Enteromorpha was used as the raw material, the Enteromorpha was first hydrolyzed with oxalic acid and purified before use in the reaction, while other conditions remained unchanged.