Methods for improving the activity of phenolic ether compounds for hydrogenolysis and for modulating product selectivity
By adding trace amounts of alcohol and water to the hydrogenolysis reaction of phenolic ether compounds, and utilizing the alcohol to form a hydrogen bond network on the catalyst surface, the safety risks and low-value-added product generation problems of traditional hydrogenolysis technology are solved, realizing a green hydrogenolysis method for the efficient and selective preparation of phenolic products.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- YANGZHOU UNIV
- Filing Date
- 2026-03-26
- Publication Date
- 2026-05-29
AI Technical Summary
Existing hydrogenolysis technologies pose safety risks and generate low-value-added products under high temperature and pressure. Furthermore, separating hydrogenolysis products and byproducts is difficult. Traditional catalytic transfer hydrogenolysis using external hydrogen is neither economical nor environmentally friendly.
In the hydrogenolysis reaction of phenolic ether compounds, trace amounts of alcohol and water are added as solvents. The alcohol forms a hydrogen bond network on the catalyst surface, which promotes the reforming of meth/eth/propoxy functional groups in the reactants to produce hydrogen, thereby improving the activity and selectively preparing phenolic products. Supported platinum-based, ruthenium-based, or Ni-based metal catalysts are used, and the support is carbon black or oxide, while the reaction conditions remain unchanged.
Without increasing reaction pressure and temperature, the hydrogenolysis activity and selectivity of phenolic ether compounds are significantly improved. The addition of alcohols changes the hydrogen bond network on the catalyst surface, and the generated phenolic products are easy to separate, providing a green and efficient biomass conversion strategy.
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Figure CN122102851A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of catalyst technology and relates to methods for improving the activity of hydrogenolysis of phenolic ether compounds and adjusting the selectivity of products. Background Technology
[0002] Against the backdrop of continuously growing global energy demand and increasingly depleted fossil resources, the development and utilization of renewable energy has become an important way to alleviate the energy crisis and environmental pressure. As the only renewable carbon source, the efficient conversion and utilization of biomass is of profound significance for achieving the goal of carbon neutrality.
[0003] Hydrogenolysis technology has been considered one of the most effective strategies for the high-value conversion of lignin in recent years. Traditional hydrogenolysis processes use grey hydrogen under high temperature and pressure, posing significant safety risks and a large carbon footprint. Furthermore, due to the high hydrogen pressure, the generated aromatic hydrocarbon products are further hydrogenated to produce low-value-added over-hydrogenated products such as cyclohexanol, cyclohexanone, and cyclohexane, reducing the value-added applications of biomass. Catalytic transfer hydrogenolysis (CTH) using liquid organic molecules (formic acid, methanol, ethanol, and isopropanol, etc.) as hydrogen donors is also an effective hydrogenolysis strategy. However, due to the large number of dehydrogenation byproducts generated during the reaction, separating the hydrogenolysis products from these unwanted byproducts is quite difficult.
[0004] Recent reports indicate that a self-supplying hydrogenolysis strategy for lignin aqueous reforming effectively reduces carbon emissions, providing a promising alternative to traditional biorefining processes. [1,2] Lignin contains a large number of oxygen-containing functional groups (phenolic hydroxyl and methoxy groups), which can serve as renewable hydrogen donors. By reforming in an aqueous environment, a sustainable hydrogen source is provided for the reaction, and over-hydrogenation is avoided. Summary of the Invention
[0005] The technical problem solved by this invention is to provide a method for improving the hydrogenolysis activity of phenolic ether compounds and adjusting product selectivity, without using external hydrogen gas, using green solvent water, or increasing the severity of process conditions including reaction temperature and pressure. By adding a trace amount of alcohol to the reaction system, hydrogen production is promoted through reforming of the methoxy / ethoxy functional groups in water and reactants without participating in the reaction or generating additional byproducts. This controllably enhances the hydrogenolysis activity of phenolic ether compounds and provides highly selective preparation of phenolic products.
[0006] The method for improving the activity of hydrogenolysis of phenolic ether compounds and adjusting the product selectivity according to the present invention is as follows: In a batch reactor, phenolic ether compounds and trace amounts of alcohol-water mixture are subjected to hydrogenolysis in the presence of a metal catalyst to generate the corresponding phenolic products.
[0007] The phenolic ether compounds are one of guaiacol, m-methoxyphenol, p-methoxyphenol, 2-ethoxyphenol, or 2-propoxyphenol. These compounds contain methoxy / ethoxy / propoxy and hydroxyl phenolic ethers, and undergo hydrogenolysis involving the cleavage of both ArO-CH3 and Ar-OCH3 bonds. The phenolic products are phenol and dihydroxyphenol.
[0008] The metal catalyst is a supported platinum-based, ruthenium-based, or Ni-based metal catalyst, and the support is carbon black or an oxide support, wherein the oxide support is MgO, Al2O3, TiO2, or CeO2, and the metal loading in the metal catalyst is 1~5wt%.
[0009] The trace alcohol is methanol, ethanol, or n-propanol. When methanol is used, the methanol concentration in the methanol-water mixture is 247-493 mmol / L. When ethanol is used, the ethanol concentration in the ethanol-water mixture is 29-58 mmol / L. When propanol is used, the propanol concentration in the propanol-water mixture is 22-44 mmol / L.
[0010] Furthermore, the experimental procedure involved placing the catalyst, phenolic ether compounds, and trace amounts of alcohol-water solution into a batch reactor, and then purging and releasing the reactor with inert gas to remove all air from the reactor. Subsequently, the reactor was pressurized to the reaction pressure and heated to the reaction temperature. Finally, the stirring was turned on to carry out the reaction, and samples were taken periodically for data analysis.
[0011] In the reaction system, the amount of catalyst used is 100~2000 mg / L, and the concentration of phenolic ether compounds is 10~300 mmol / L.
[0012] The inert gas is nitrogen, argon, or helium; the number of charging and discharging cycles is 5 to 10, with each charging and discharging cycle having a gas pressure of 0.1 to 3 MPa and a reaction pressure of 0.1 to 5 MPa.
[0013] The reaction temperature is 160~200 ℃, the stirring rate is 600~1000 rpm, the reaction time is 1~5 h, and the sampling interval is 5~60 min.
[0014] This invention employs a trace alcohol-water reforming method for self-hydrogenation of phenolic ether compounds, primarily utilizing the alteration of the reaction microenvironment by the alcohol, specifically the formation of a hydrogen bond network on the catalyst surface. This network can transfer hydrogen atoms to adjacent phenolic ether compounds more rapidly and directly than water molecules, thereby achieving a highly efficient surface hydrogen transfer process.
[0015] Compared with the prior art, the advantages of the present invention are as follows: This invention significantly improves the hydrogenolysis activity of the reactants and the selectivity of phenol by adding only a trace amount of alcohol to the reaction system. Using water and a trace amount of alcohol as the reaction solvent is not only more economical and environmentally friendly compared to the traditional CTH strategy. The alcohol in the reaction system mainly alters the hydrogen bonding network on the catalyst surface and does not participate in the reaction to generate aldehyde or ketone byproducts. Furthermore, the alcohol content is low, and its boiling point differs significantly from the product, making it easy to separate. In summary, this invention provides a novel and efficient reaction scheme for biomass monomer conversion, offering valuable strategies and catalyst design ideas for green and sustainable biomass conversion. Attached Figure Description
[0016] Figure 1 The reaction equations are for the hydrogenolysis reactions of the various phenolic ether compounds of this invention.
[0017] Figure 2 The graph shows the changes in the conversion and selectivity of guaiacol with the amount of methanol added in Example 1 on a commercial Pt / C catalyst and in a methanol-water system.
[0018] Figure 3 The graph shows the changes in the conversion and selectivity of guaiacol with the amount of ethanol added in Example 2 on a commercial Pt / C catalyst and in an ethanol-water system.
[0019] Figure 4 The graph shows the changes in the conversion and selectivity of guaiacol with the amount of propanol added in Example 3 on a commercial Pt / C catalyst and in a propanol-water system.
[0020] Figure 5 The graph shows the change of TOF with alcohol concentration in Examples 1, 2, and 3.
[0021] Figure 6 This is a graph showing the conversion and selectivity of various phenolic ether compounds in Example 4 on a commercial Pt / C catalyst and in a pure water system.
[0022] Figure 7 This is a graph showing the conversion and selectivity of various phenolic ether compounds in Example 5 on a commercial Pt / C catalyst and in an ethanol-water system.
[0023] Figure 8 This is a graph showing the change in the peak area ratio of ethanol and internal standard over reaction time in Example 1 on a commercial Pt / C catalyst and in a methanol-water system.
[0024] Figure 9 The graph shows the changes in conversion and product yield over reaction time in Example 1 using a commercial Pt / C catalyst and a methanol-water system (0.3 mL of methanol added).
[0025] Figure 10The graph shows the changes in the conversion and selectivity of guaiacol with the amount of ethanol added in Example 6 on a commercial Ru / C catalyst and in an ethanol-water system. Detailed Implementation
[0026] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims of the present invention.
[0027] Figure 1 The product formation of each phenol ether compound by hydrogenolysis in the absence of exogenous hydrogen is shown, which are phenol and dihydroxyphenol. Example 1
[0028] In a 50 mL mechanically stirred reactor, 1 mmol of guaiacol, 30 mL of water, 50 mg of commercial Pt / C (carrier: carbon black, metal loading: 5 wt%), and a certain amount of methanol (added stepwise from 0-20 mL) were added. After sealing the reactor, the mixture was purged five times with pure N2 to completely remove residual air. Subsequently, pure N2 was introduced into the reactor to 0.5 MPa, the temperature was raised to 180 °C, and stirring was started (800 rpm). During the reaction, samples were taken periodically (0.5 mL), extracted with 2 mL of ethyl acetate containing 30 mM hexadecane (internal standard), and analyzed by gas chromatography.
[0029] Depend on Figure 2 It is observed that the conversion rate of guaiacol exhibits a volcanic trend with increasing methanol addition, reaching its highest value within the range of 0.3–0.6 mL (corresponding to 7.41 mmol–14.81 mmol). Furthermore, the selectivity of phenol gradually increases with increasing methanol content, reaching its maximum at 0.6 mL of methanol. Further increases in methanol concentration lead to the formation of perhydrogenated products such as cyclohexanol and cyclohexanone. Therefore, the preferred methanol concentration range in the trace alcohol-water mixture is 247–493 mmol / L. At 0.6 mL of methanol, the conversion rate is 79%, which is 10 times that of the pure water system (7.5%). It is noteworthy that when methanol is in excess, the conversion rate gradually decreases until it reaches zero.
[0030] Changing the catalyst support to MgO, Al2O3, TiO2 or CeO2 has the same technical effect as in Example 1. Changing the metal loading in the catalyst to 1 wt%, 2 wt%, 3 wt% and 4 wt% has no substantial effect on the conversion rate and methanol usage, only affecting the reaction time. Example 2
[0031] In a 50 mL mechanically stirred reactor, add 1 mmol of guaiacol, 30 mL of water, 50 mg of commercial Pt / C (carrier: carbon black, metal loading: 5 wt%), and a certain amount of ethanol (0-5 mL). After sealing the reactor, purge with pure N2 five times to completely remove residual air. Then, introduce pure N2 into the reactor to 0.5 MPa, raise the temperature to 180 °C, and start stirring (800 rpm). During the reaction, periodically take samples (0.5 mL), extract with 2 mL of ethyl acetate containing 30 mM hexadecane (internal standard), and analyze by gas chromatography.
[0032] Depend on Figure 3 It is observed that the conversion rate of guaiacol exhibits a volcanic-like trend with varying ethanol addition, and the selectivity of phenol initially increases and then decreases (further generating cyclohexanol and cyclohexanone). The conversion rate reaches its maximum of approximately 75% when the addition amount is 0.05–0.1 mL (0.86 mmol to 1.72 mmol), which is also 10 times that of the pure water system. Excess ethanol reduces the activity to zero. Therefore, the preferred ethanol concentration range in the trace alcohol-water mixture is 29–58 mmol / L.
[0033] Depend on Figure 8 It can be seen that the peak area ratio of methanol to internal standard remained unchanged during the reaction process, indicating that methanol does not participate in the reaction, but affects the microenvironment of the reaction, namely the hydrogen bond network, thereby improving the catalytic activity.
[0034] Depend on Figure 9 It can be seen that in the later stage of the reaction, catechol will gradually be converted into phenol, which is the main reason for the increase in phenol conversion rate after the reaction is completed. Example 3
[0035] In a 50 mL mechanically stirred reactor, 1 mmol of guaiacol, 30 mL of water, 50 mg of commercial Pt / C (carrier: carbon black, metal loading: 5 wt%), and a certain amount of propanol (0-0.5 mL) were added. After sealing the reactor, it was purged five times with pure N2 to completely remove residual air. Subsequently, pure N2 was introduced into the reactor to 0.5 MPa, the temperature was raised to 180 °C, and stirring was started (800 rpm). During the reaction, samples (0.5 mL) were taken periodically, extracted with 2 mL of ethyl acetate containing 30 mM hexadecane (internal standard), and detected by gas chromatography.
[0036] Depend on Figure 4It can be seen that the conversion rate of guaiacol changes with the amount of propanol added in the same way as that of methanol and ethanol, exhibiting a volcanic pattern. Furthermore, the selectivity of phenol gradually increases with increasing propanol content. The conversion rate is relatively high when the propanol addition is 0.05–0.1 mL, with the best effect observed at 0.1 mL. Therefore, in the propanol-water mixture, the preferred concentration of propanol is 22–44 mmol / L.
[0037] Figure 5 The study showed that the TOF (Time-of-Flight) of three alcohols (methanol, ethanol, and propanol) varied with alcohol concentration. Similar to the conversion rate, the TOF exhibited a volcanic pattern with alcohol concentration. However, methanol showed the highest peak activity and the largest range of TOF variation with alcohol concentration, while propanol showed the smallest. This indicates that the length of the carbon chain also affects the hydrogen bond network. Experiments with the three alcohols also demonstrated the applicability of this system. Example 4
[0038] In a 50 mL mechanically stirred reactor, 1 mmol of each phenolic ether compound (guaiacol, m-methoxyphenol, p-methoxyphenol, 2-ethoxyphenol, 2-propoxyphenol), 30 mL of water, and 50 mg of commercial Pt / C (carbon black as support, metal loading 5 wt%) were added. After sealing the reactor, it was purged five times with pure N2 to completely remove residual air. Then, pure N2 was introduced into the reactor to 0.5 MPa, the temperature was raised to 180 °C, and stirring was started (800 rpm). During the reaction, samples (0.5 mL) were taken periodically, extracted with 2 mL of ethyl acetate containing 30 mM hexadecane (internal standard), and analyzed by gas chromatography.
[0039] Depend on Figure 6 It can be seen that, in a pure water system, the conversion rates of various phenolic ether compounds are all at a low level (<30%), and there is no activity at all on o-propoxyphenol. Example 5
[0040] In a 50 mL mechanically stirred reactor, 1 mmol of each phenolic ether compound (guaiacol, m-methoxyphenol, p-methoxyphenol, 2-ethoxyphenol, 2-propoxyphenol), 30 mL of water, 50 mg of commercial Pt / C (carrier: carbon black, metal loading: 5 wt%), and 0.1 mL of ethanol (57.1 mmol / L) were added. After sealing the reactor, it was purged five times with pure N2 to completely remove residual air. Then, pure N2 was introduced into the reactor to 0.5 MPa, the temperature was raised to 180 °C, and stirring was started (800 rpm). During the reaction, samples (0.5 mL) were taken periodically, extracted with 2 mL of ethyl acetate containing 30 mM hexadecane (internal standard), and analyzed by gas chromatography.
[0041] Depend on Figure 7 It can be seen that adding 0.1 mL of ethanol to pure water significantly improved the conversion rates of all phenolic ether compounds. In particular, o-propoxyphenol, which is inactive in pure water, achieved a conversion rate of 35% in the ethanol-water system. The phenol selectivity of each phenolic ether compound was also improved to varying degrees. Example 6
[0042] Add 1 mmol of guaiacol, 30 mL of water, 50 mg of commercial Ru / C, and a certain amount of ethanol (0–0.2 mL) to a 50 mL mechanically stirred reactor. After sealing the reactor, purge it five times with pure N2 to completely remove any residual air. Then, introduce pure N2 into the reactor to 0.5 MPa, raise the temperature to 180 °C, and start stirring (800 rpm). During the reaction, take 0.5 mL samples periodically, extract them with 2 mL of ethyl acetate containing 30 mM hexadecane (internal standard), and detect them by gas chromatography.
[0043] Depend on Figure 10 It can be seen that, on a commercial Ru / C catalyst with a metal loading of 5 wt%, the conversion rate and reaction rate of guaiacol still exhibit a volcanic trend with increasing ethanol addition, and the activity reaches its maximum when the ethanol addition is 0.05 mL, at which point the conversion rate is 30% and the reaction rate is 60 mmol. GUA g Pt -1 h -1 .
[0044] To explore the general applicability of the scheme, the inventors conducted further experiments. These experiments demonstrated that the metal catalyst can be a supported platinum-based, ruthenium-based, or Ni-based metal catalyst. Besides carbon black, the supporting material can also be an oxide support, such as MgO, Al₂O₃, TiO₂, or CeO₂. The metal loading in the metal catalyst is 1–5 wt%. In the reaction system, the catalyst dosage can be 100–200 mg / L.
[0045] Phenolic ether compounds, in addition to guaiacol, can also be m-methoxyphenol, p-methoxyphenol, 2-ethoxyphenol, or 2-propoxyphenol. The above compounds contain methoxy / ethoxy / propoxy and hydroxyl phenolic ethers. The hydrogenolysis reaction involves the cleavage of two bonds, ArO-CH3 and Ar-OCH3, and the phenolic products are phenol and dihydroxyphenol.
[0046] In addition, the concentration range of phenolic ether compounds in the reaction system can be 10~300 mmol / L.
Claims
1. A method for improving the activity of hydrogenolysis of phenolic ether compounds and adjusting product selectivity, characterized in that, In a batch reactor, phenolic ether compounds and trace amounts of alcohol-water mixtures are subjected to hydrogenolysis in the presence of a metal catalyst to generate the corresponding phenolic products.
2. The method for improving the activity of hydrogenolysis of phenolic ether compounds and adjusting the selectivity of products according to claim 1, characterized in that, The phenolic ether compounds mentioned are one of guaiacol, m-methoxyphenol, p-methoxyphenol, 2-ethoxyphenol, or 2-propoxyphenol.
3. The method for improving the activity of hydrogenolysis of phenolic ether compounds and adjusting product selectivity according to claim 1, characterized in that, The metal catalyst is a supported platinum-based, ruthenium-based, or Ni-based metal catalyst, and the support is carbon black or an oxide support, wherein the oxide support is MgO, Al2O3, TiO2, or CeO2, and the metal loading in the metal catalyst is 1~5wt%.
4. The method for improving the activity of hydrogenolysis of phenolic ether compounds and adjusting product selectivity according to claim 1, characterized in that, The hydrogenolysis reaction involves the breaking of two bonds, ArO-CH3 and Ar-OCH3, and the phenolic products are phenol and dihydroxyphenol.
5. The method for improving the activity of hydrogenolysis of phenolic ether compounds and adjusting product selectivity according to claim 1, characterized in that, The trace alcohol is selected from methanol, ethanol, or n-propanol; when methanol is selected, the methanol concentration in the methanol-water mixture is 247~493 mmol / L; when ethanol is selected, the ethanol concentration in the ethanol-water mixture is 29~58 mmol / L; when propanol is selected, the propanol concentration in the propanol-water mixture is 22~44 mmol / L.
6. The method for improving the activity of hydrogenolysis of phenolic ether compounds and adjusting product selectivity according to claim 1, characterized in that, The experimental procedure involves placing the catalyst, phenolic ether compounds, and trace amounts of alcohol-water solution into a batch reactor, purging and releasing the reactor with inert gas, pressurizing to the reaction pressure, heating to the reaction temperature, and finally stirring to carry out the reaction. Samples are taken periodically for data analysis.
7. The method for improving the activity of hydrogenolysis of phenolic ether compounds and adjusting product selectivity according to claim 6, characterized in that, The amount of catalyst used in the reaction system is 100~2000 mg / L.
8. The method for improving the activity of hydrogenolysis of phenolic ether compounds and adjusting product selectivity according to claim 6, characterized in that, In the reaction system described, the concentration of phenolic ether compounds ranges from 10 to 300 mmol / L.
9. The method for improving the activity of hydrogenolysis of phenolic ether compounds and adjusting product selectivity according to claim 6, characterized in that, The inert gas is nitrogen, argon, or helium; the number of charging and discharging cycles is 5 to 10, with each charging and discharging cycle having a gas pressure of 0.1 to 3 MPa and a reaction pressure of 0.1 to 5 MPa.
10. The method for improving the activity of hydrogenolysis of phenolic ether compounds and adjusting product selectivity according to claim 6, characterized in that, The reaction temperature is 160~200 ℃, the stirring rate is 600~1000 rpm, the reaction time is 1~5 h, and the sampling interval is 5~60 min.