Method for promoting rhenium oxide catalyzed vicinal diol deoxidation and dehydration reaction through nitrogen-doped carbon

Abstract

The invention belongs to the field of chemical catalysis science, and particularly relates to a method for promoting rhenium oxide catalyzed vicinal diol deoxidation and dehydration reaction through nitrogen-doped carbon. Different chlorine salts are used as template agents, the reaction of starch and melamine is regulated and controlled, then the type and proportion of N species in the carbon material are regulated and controlled, different nitrogen-doped carbon materials are prepared, the N-doped carbon materials are used for ReOx loading, and the catalyst for catalyzing the DODH reaction of vicinal diol is obtained. Researches show that the nitrogen-doped carbon material prepared by using the mixed salt of LiCl and KCl as the template agent has more active N species, and the N species not only promote the dispersion of rhenium oxide, but also promote the electron transfer of ReOx, and improve the reaction activity of DODH. Finally, in the reaction with tartaric acid as a model, the yield of the obtained dimethyl succinate is 93.26%, and good cycle stability is shown. The method is low in cost and wide in substrate application range, and a new idea is provided for removal of vicinal diol hydroxyl.

Description

Technical Field

[0001] The present invention belongs to the field of chemical catalysis science, and particularly relates to a method for promoting the deoxygenation and dehydration reaction of vicinal diols catalyzed by nitrogen-doped carbon and rhenium oxide. Background Art

[0002] In recent years, biomass resources have attracted much attention due to their advantages of wide global distribution, rich reserves and renewability. Converting biomass-derived platform chemical vicinal diols into valuable chemicals is a current research hotspot. However, the high oxygen content in vicinal diol compounds limits their further use, and it is necessary to reduce the oxygen content, that is, to remove the hydroxyl groups of vicinal diols. In Patent US8669397B2, HBr is used as a substitute and Pt-Rh / SiO2 is used as a catalyst, which has a good effect on the removal of polyhydroxy compounds. However, the use of HBr in this reaction process will inevitably cause equipment corrosion and environmental pollution. In addition, in the halogen substitution hydrogenolysis method, the OH groups are removed one by one, and the OH removal efficiency is low.

[0003] Deoxygenation and dehydration reaction (DODH) is an emerging strategy for removing two adjacent hydroxyl groups in diols and has recently been developed for the deoxygenation of biomass-derived alcohols. During the DODH reaction process, the two hydroxyl groups in the substrate vicinal diol first coordinate with a high-valent transition metal oxide through dehydration to form a chelate, and then under the action of a reducing agent, the two C-O bonds are broken simultaneously to generate a deoxygenated product olefin. It can be seen from the DODH reaction process that this method is not only green and environmentally friendly, but also has high product selectivity because the two hydroxyl groups are removed simultaneously. Among them, Re-based catalysts are the most efficient catalysts in DODH.

[0004] Literature ( ChemCatChem 2013, 5, 3567−3570) reported that diethyl tartrate was used as a raw material in a high-pressure reactor, and ReO x / C was used as a catalyst. At 1.4 MPa H2 and 150 °C, the reaction was carried out for 48 h, and the yield of diethyl fumarate was 95%. Although this scheme achieved efficient conversion of DODH, the ReO x in this catalyst was easily lost, resulting in a rapid decline in activity.

[0005] Patent US202117907359A and literature ( ACS Catal . 2016, 6, 677−680) ( ChemCatChem 2021, 13, 2393−2397) proposed to adjust the interaction between ReO x and the support by changing the support type (CeO2, TiO2, ZSM-5) of ReO x to improve the interaction between ReO xStability and DODH reactivity. Research shows that as the acidity of the support increases, the interaction between ReO x and the support becomes stronger, the catalyst stability becomes stronger, and the DODH reactivity becomes higher. Patent CN 110872222 B and the literature ( ACS Catal .2021,11,95−109), ( Angew. Chem. Int. Ed .2021, 60, 4712−4719), ( Catal. Sci. Technol .,2023,13,714–725) propose introducing noble metal M (Pt, Pd, Ir) into ReO x / C to prepare M-ReO x / C bimetallic catalysts. Research shows that the introduction of noble metals can, on the one hand, improve the dispersion degree of ReO x on the support, and on the other hand, noble metals can decompose hydrogen, promoting the redox of ReO x active species and the hydrogenation of unsaturated products in the DODH reaction. Although the catalytic performance of noble metals is very high, their prices are expensive and resources are scarce, making the cost of this catalyst relatively high. In summary, for the deoxygenation and dehydration reaction of polyhydroxy compounds, without the participation of auxiliary metals, the dispersion degree of ReO x on the support is relatively low, resulting in a relatively low DODH reaction efficiency, and it is almost impossible to activate H2, making the redox of ReO x in the DODH reaction relatively difficult and the product yield relatively low. After introducing noble metals, the catalyst cost will increase. SUMMARY OF THE INVENTION

[0006] The object of the present invention is to overcome the shortcomings of the prior art and prepare a ReO x / NC bifunctional catalyst. The present invention is a method for promoting the deoxygenation and dehydration reaction (DODH) of vicinal diols catalyzed by rhenium oxide (ReO x ) with nitrogen-doped carbon (NC), focusing on regulating the N sites to promote the electron transfer of ReO x , thereby promoting the DODH reaction catalyzed by ReO x . The present invention utilizes the interaction between the N sites and rhenium oxide to solve the problem of difficult redox reaction of rhenium oxide in the vicinal diol DODH reaction and improve the efficiency of removing hydroxyl groups from vicinal diols. At the same time, the N sites can also activate hydrogen to achieve the hydrogenation reaction of unsaturated olefins in the DODH reaction. In the present invention, a low-cost non-metallic NC support is used to load ReO x , and by regulating the N type and proportion on the NC, the dispersion and electron transfer effect of ReO x on the support surface are promoted. At the same time, the N sites can also dissociate H2, thereby promoting the efficient coupling of the DODH reaction and the fumaric acid hydrogenation reaction, and realizing the one-step conversion of polyhydroxy compounds into saturated hydrocarbon products.

[0007] The present invention adopts the following technical solution: A method for promoting the deoxidation and dehydration reaction of vicinal diols catalyzed by rhenium oxide by nitrogen-doped carbon, specifically comprising the following steps: (1) Starch and melamine were used as raw materials and metal chloride was used as template. Water was added and stirred thoroughly, and then the water was evaporated in a water bath and dried overnight at 100 °C. The dried product was transferred to a tube furnace for high-temperature calcination. After the solid was ground, the template was washed off with a large amount of deionized water, and the nitrogen-doped carbon material was obtained by vacuum drying overnight. The perrhenate was dispersed in the prepared nitrogen-doped carbon aqueous solution by the excess impregnation method, stirred overnight, evaporated in a water bath and dried, and the dried product was transferred to a tube furnace for calcination to obtain a nitrogen-doped carbon-supported rhenium oxide catalyst ReO x / NC.

[0008] (2) Weigh a certain amount of vicinal diol, nitrogen-doped carbon-supported rhenium oxide catalyst, and Amberlyst-15 and transfer them to a high-pressure reactor. Add an organic solvent, replace the air in the reactor with an inert gas three times, and then fill the reactor with hydrogen. After heating for a period of time, stop heating and cool naturally to room temperature. The resulting liquid is separated by an organic filter membrane and then analyzed by gas phase.

[0009] Furthermore, in step (1), the mass ratio of starch, melamine and metal chloride salt is 1:2:1. Furthermore, the chloride salt in step (1) includes one or more of LiCl, NaCl, KCl, ZnCl2, AlCl3, FeCl3 and the like.

[0010] Furthermore, the high temperature calcination temperature in step (1) is 500°C-800°C. The water bath temperature in step (1) is 80°C.

[0011] Furthermore, in step (2), the mass ratio of the vicinal diol, the nitrogen-doped carbon-supported rhenium oxide catalyst, and Amberlyst-15 is 2:1:1.

[0012] Furthermore, the vicinal diol in step (2) includes one or more of L-tartaric acid, DL-tartaric acid, mucic acid, glucaric acid, and ribonucleic acid-1,4-lactone.

[0013] Furthermore, the organic solvent in step (2) includes any one or more of methanol, ethanol, isopropanol, and n-butanol.

[0014] Furthermore, the reaction temperature in step (2) is 80-140°C, the reaction pressure is 1-2 MPa, and the reaction time is 8-14 h.

[0015] The significant advantages of the present invention are: The present invention first uses a non-metallic N-doped carbon material as a carrier for dispersing ReO x , avoiding the use of metals such as Ru, Rh, Pd, etc. in the DODH reaction and reducing the catalyst cost of the DODH reaction. By forming a nitrogen-rich precursor from starch and melamine under the catalysis of metal chlorides and then calcining to obtain an N-doped carbon carrier, the introduction of N can promote the dispersion and electron transfer of ReO x , thereby accelerating the reaction cycle of DODH and promoting the dehydroxylation reaction of vicinal diols. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Synthesis route diagram of nitrogen-doped carbon.

[0017] Figure 2 H2-TPR diagram of rhenium oxide supported on nitrogen-doped carbon. DETAILED DESCRIPTION OF THE INVENTION

[0018] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0019] Example 1 (1) Using 2 g of starch and 4 g of melamine as raw materials, 2 g of LiCl as a template agent, adding water and stirring for 2 h, then evaporating the water by water bath, drying overnight at 100 °C, transferring the dried product to a tubular furnace and calcining at 800 °C for 1 h, obtaining a solid, grinding it, washing away the template agent with a large amount of deionized water, and drying under vacuum overnight to obtain a nitrogen-doped carbon material; using the excess impregnation method, dispersing 0.1 g of perrhenate in the aqueous solution of the prepared nitrogen-doped carbon, stirring overnight, evaporating the water by water bath at 80 °C and then drying, transferring the dried product to a tubular furnace and roasting at 400 °C for 3 h to obtain a rhenium oxide supported on nitrogen-doped carbon catalyst, denoted as ReO x / NC -Li .

[0020] (2) Weighing 0.09 g of tartaric acid, 0.05 g of ReO x / NC -Li catalyst, and 0.05 g of Amberlyst-15, transferring them to a high-pressure reaction kettle, adding 30 ml of methanol solvent, purging with hydrogen at least 5 times, filling 2 MPa of hydrogen into the reaction kettle, heating the temperature program to 120 °C, stirring speed of 500 rpm, stopping heating after reacting for 12 h, and naturally cooling to room temperature. Performing gas phase analysis on the reacted liquid, the results show that the yield of dimethyl fumarate is 14.24% and the yield of dimethyl succinate is 68.34%.

[0021] Example 2 (1) Using 2 g of starch and 4 g of melamine as raw materials, 2 g of NaCl as a templating agent, adding water and stirring for 2 h, then evaporating the water by water bath, drying overnight at 100 °C. Transfer the dried product to a tubular furnace and calcine at 800 °C for 1 h. Grind the obtained solid and wash away the templating agent with a large amount of deionized water, then dry overnight under vacuum to obtain a nitrogen-doped carbon material. Using the excess impregnation method, disperse 0.1 g of perrhenate in the aqueous solution of the prepared nitrogen-doped carbon, stir overnight, evaporate the water by water bath at 80 °C and then dry. Transfer the dried product to a tubular furnace and calcine at 400 °C for 3 h to obtain a rhenium oxide supported on nitrogen-doped carbon catalyst, denoted as ReO x / NC -Na .

[0022] (2) Weigh 0.09 g of tartaric acid, 0.05 g of the ReO x / NC -Na catalyst, and 0.05 g of Amberlyst-15, transfer them to a high-pressure reactor, add 30 ml of methanol solvent, displace with hydrogen at least 5 times, charge 2 MPa of hydrogen into the reactor, raise the temperature programmatically to 120 °C, stir at a speed of 500 rpm, stop heating after reacting for 12 h, and naturally cool to room temperature. Perform gas phase analysis on the reacted liquid. The results show that the yield of dimethyl fumarate is 0, and the yield of dimethyl succinate is 9.65%.

[0023] Example 3 (1) Using 2 g of starch and 4 g of melamine as raw materials, 2 g of KCl as a templating agent, adding water and stirring for 2 h, then evaporating the water by water bath, drying overnight at 100 °C. Transfer the dried product to a tubular furnace and calcine at 800 °C for 1 h. Grind the obtained solid and wash away the templating agent with a large amount of deionized water, then dry overnight under vacuum to obtain a nitrogen-doped carbon material. Using the excess impregnation method, disperse the perrhenate in the aqueous solution of the prepared nitrogen-doped carbon, stir overnight, evaporate the water by water bath at 80 °C and then dry. Transfer the dried product to a tubular furnace and calcine at 400 °C for 3 h to obtain a rhenium oxide supported on nitrogen-doped carbon catalyst, denoted as ReO x / NC -K .

[0024] (2) Weigh 0.09 g of tartaric acid, 0.05 g of the ReO x / NC -K catalyst, and 0.05 g of Amberlyst-15, transfer them to a high-pressure reactor, add 30 ml of methanol solvent, displace with hydrogen at least 5 times, charge 2 MPa of hydrogen into the reactor, raise the temperature programmatically to 120 °C, stir at a speed of 500 rpm, stop heating after reacting for 12 h, and naturally cool to room temperature. Perform gas phase analysis on the reacted liquid. The results show that the yield of dimethyl fumarate is 1.30%, and the yield of dimethyl succinate is 25.45%.

[0025] Example 4 (1)Using 2 g of starch and 4 g of melamine as raw materials, 2 g of a mixed double salt of LiCl and KCl as a template agent, adding water and stirring for 2 h, then evaporating the water by water bath, drying overnight at 100 °C. Transfer the dried product to a tubular furnace and calcine at 800 °C for 1 h. Grind the obtained solid and wash away the template agent with a large amount of deionized water, and then dry overnight under vacuum to obtain a nitrogen-doped carbon material. Using the excessive impregnation method, disperse the perrhenate in the aqueous solution of the prepared nitrogen-doped carbon, stir overnight, evaporate the water by water bath at 80 °C and then dry. Transfer the dried product to a tubular furnace and calcine at 400 °C for 3 h to obtain a rhenium oxide supported on nitrogen-doped carbon catalyst, denoted as ReO x / NC -Li+K 。

[0026] (2)Weigh 0.09 g of tartaric acid, 0.05 g of the ReO x / NC -Li+K catalyst, and 0.05 g of Amberlyst-15 and transfer them to a high-pressure reactor. Add 30 ml of methanol solvent, displace with hydrogen at least 5 times, fill the reactor with 2 MPa of hydrogen, raise the temperature programmatically to 120 °C, stir at a speed of 500 rpm, stop heating after reacting for 12 h, and naturally cool to room temperature. Perform gas phase analysis on the reacted liquid. The results show that the yield of dimethyl fumarate is 0, and the yield of dimethyl succinate is 93.26%.

[0027] Example 5 Weigh 0.05 g of the ReO x / NC -Li+K catalyst in Example 4, 0.09 g of tartaric acid, and Amberlyst-15 and transfer them to a high-pressure reactor. Add 30 ml of methanol solvent, displace with hydrogen at least 5 times, fill the reactor with 2 MPa of hydrogen, raise the temperature programmatically to 100 °C, stir at a speed of 500 rpm, stop heating after reacting for 12 h, and naturally cool to room temperature. Perform gas phase analysis on the reacted liquid. The results show that the yield of dimethyl fumarate is 17.11%, and the yield of dimethyl succinate is 70.68%.

[0028] Example 6 Weigh the ReO x / NC -Li+K0.05 g of catalyst, 0.09 g of tartaric acid, and 0.05 g of Amberlyst-15 were transferred to a high-pressure reactor. 30 ml of isopropyl alcohol solvent was added, and the system was purged with hydrogen at least 5 times. Then, 2 MPa of hydrogen was charged into the reactor. The temperature was raised to 120 °C at a programmed rate, the stirring speed was 500 rpm, and the reaction was carried out for 12 h. After that, heating was stopped and the system was allowed to cool naturally to room temperature. The liquid after the reaction was analyzed by gas chromatography. The results showed that the yield of isopropyl fumarate was 45.74% and the yield of isopropyl succinate was 37.35%.

[0029] Example 7 Weigh the ReO in Example 4 x / NC -Li+K 0.05 g of catalyst, 0.126 g of mucic acid, and 0.05 g of Amberlyst-15 were transferred to a high-pressure reactor. 30 ml of methanol solvent was added, and the system was purged with hydrogen at least 5 times. Then, 2 MPa of hydrogen was charged into the reactor. The temperature was raised to 120 °C at a programmed rate, the stirring speed was 500 rpm, and the reaction was carried out for 24 h. After that, heating was stopped and the system was allowed to cool naturally to room temperature. The liquid after the reaction was analyzed by gas chromatography. The results showed that the yield of dimethyl 2-hexenedioate was 14.85%, the yield of dimethyl 3-hexenedioate was 19.94%, and the yield of dimethyl adipate was 42.19%.

[0030] Comparative Example 1 (without adding template agent) (1) Using 2 g of starch and 4 g of melamine as raw materials (the mass ratio of the two is 1:2), add water and stir for 2 h, then evaporate the water by water bath, dry overnight at 100 °C. Transfer the dried product to a tube furnace and calcine at 800 °C for 1 h. Grind the obtained solid and wash away the template agent with a large amount of deionized water, and then dry overnight under vacuum to obtain a nitrogen-doped carbon material. Using the impregnation method in excess, disperse 0.1 g of perrhenate in the aqueous solution of the prepared nitrogen-doped carbon, stir overnight, evaporate the water by water bath at 80 °C and then dry. Transfer the dried product to a tube furnace and calcine at 400 °C for 3 h to obtain a rhenium oxide supported on nitrogen-doped carbon catalyst, denoted as ReO x / NC -no .

[0031] (2) Weigh 0.09 g of tartaric acid, ReO x / NC -no 0.05 g of catalyst and 0.05 g of Amberlyst-15 were transferred to a high-pressure reactor. 30 ml of methanol solvent was added, and the system was purged with hydrogen at least 5 times. Then, 2 MPa of hydrogen was charged into the reactor. The temperature was raised to 120 °C at a programmed rate, the stirring speed was 500 rpm, and the reaction was carried out for 12 h. After that, heating was stopped and the system was allowed to cool naturally to room temperature. The liquid after the reaction was analyzed by gas chromatography. The results showed that the yield of dimethyl fumarate was 0 and the yield of dimethyl succinate was 1.88%.

[0032] In summary, the present invention combines nitrogen-doped carbon with rhenium oxide catalyst. Through the coordination binding and synergistic catalysis between the N site and rhenium oxide, the removal of vicinal diol on tartaric acid is promoted. At the same time, nitrogen-doped carbon can also hydrogenate dimethyl fumarate, realizing the one-step conversion of tartaric acid to succinic acid. Under the optimal reaction conditions, tartaric acid is nearly completely converted, and the yield of dimethyl succinate is 93.26%. Figure 2 H2-TPR characterization shows that N has an obvious promoting effect on the reduction of ReO x

[0033] The above embodiments are only preferred embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered within the protection scope of the present invention.​

Claims

1. A method for promoting the deoxygenation and dehydration reaction of vicinal diols catalyzed by rhenium oxide with nitrogen-doped carbon, which is characterized in that: It includes the following steps: (1) Using starch and melamine as raw materials, metal chloride as a templating agent, adding water and stirring well, then evaporating the water by water bath and drying overnight at 100 °C. Transfer the dried product to a tube furnace for high-temperature calcination, grind the obtained solid, and wash away the templating agent with a large amount of deionized water, then dry under vacuum overnight to obtain a nitrogen-doped carbon material; Using the excess impregnation method, disperse perrhenate in the aqueous solution of the prepared nitrogen-doped carbon, stir overnight, evaporate the water by water bath and then dry. Transfer the dried product to a tube furnace for roasting to obtain a rhenium oxide supported on nitrogen-doped carbon catalyst ReO x / NC; (2) Weigh a certain amount of vicinal diol, rhenium oxide supported on nitrogen-doped carbon catalyst, and Amberlyst-15, transfer them to a high-pressure reactor, add an organic solvent, displace the air in the reactor 3 times with an inert gas to remove the air in the reactor, then fill the reactor with hydrogen, heat the reaction for a period of time and then stop heating, and naturally cool to room temperature; the obtained liquid is separated by an organic filter membrane and then subjected to gas phase analysis.

2. The method for promoting the deoxygenation and dehydration reaction of vicinal diols catalyzed by rhenium oxide with nitrogen-doped carbon according to claim 1, characterized in that: The chloride salt described in step (1) includes one or more of LiCl, NaCl, KCl, ZnCl2, AlCl3, and FeCl3.

3. A method for promoting the deoxygenation and dehydration reaction of vicinal diols catalyzed by rhenium oxide with nitrogen-doped carbon, characterized in that: In step (1), the mass ratio of starch, melamine, and metal chloride salt is 1:2:

1.

4. A method for nitrogen-doped carbon-promoted rhenium oxide-catalyzed deoxygenation and dehydration reaction of vicinal diols according to claim 1, characterized in that: The high-temperature calcination temperature described in step (1) is 500 °C - 800 °C.

5. A method for nitrogen-doped carbon promoted rhenium oxide-catalyzed deoxygenation and dehydration reaction of vicinal diols according to claim 1, characterized in that: The vicinal diol described in step (2) includes one or several of L-tartaric acid, DL-tartaric acid, mucic acid, glucaric acid, and ribonic acid-1,4-lactone.

6. A method for promoting the deoxygenation and dehydration reaction of vicinal diols catalyzed by rhenium oxide with nitrogen-doped carbon, characterized in that: In step (2), the mass ratio of vicinal diol, rhenium oxide supported on nitrogen-doped carbon catalyst, and Amberlyst-15 is 2:1:

1.

7. A method for promoting the deoxygenation and dehydration reaction of vicinal diols catalyzed by rhenium oxide with nitrogen-doped carbon, characterized in that: The organic solvent described in step (2) includes any one or several of methanol, ethanol, isopropanol, and n-butanol.

8. A method for nitrogen-doped carbon-promoted oxidation rhenium-catalyzed deoxygenation dehydration reaction of vicinal diols according to claim 1, characterized in that: The reaction temperature described in step (2) is 80 - 140 °C, the reaction pressure is 1 - 2 MPa, and the reaction time is 8 - 14 h.

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