A method for preparing a hydroxyl-terminated linear diol by catalytic ring-opening hydrogenation of a furan ring compound

Abstract

This invention relates to a method for catalytic ring-opening hydrogenation of furan ring compounds to prepare terminal hydroxyl straight-chain diols. The method comprises catalyzing the ring-opening hydrogenation of the furan ring compound in the presence of a catalyst supported on a non-noble metal M and trace amounts of metal Fe (M-Fe / support), under a H2 atmosphere of 1-4 MPa, at a temperature of 100-200 °C for 1-6 h, thereby obtaining the desired terminal hydroxyl straight-chain diol product in a one-pot process. Compared with existing related technologies, the method of this invention not only enables the one-pot preparation of the desired terminal hydroxyl straight-chain diol under milder H2 pressure and lower temperature, but also achieves higher selectivity or yield of the target product. Furthermore, the furan ring compound used as a raw material in this invention is derived from biomass.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of catalytic reactions, and more particularly to a method for preparing a terminal hydroxyl linear diol with high selectivity by catalytic ring-opening hydrogenation of a furan ring compound in one pot. BACKGROUND

[0002] Terminal hydroxyl linear diols, such as 1,5-pentanediol or 1,6-hexanediol, are important chemical raw materials and have been widely used in the production of polyesters, polyurethanes, solvents or additives, etc. With the increasing demand for terminal hydroxyl linear diols in industry, the global market demand for 1,5-pentanediol and 1,6-hexanediol has exceeded 4 billion yuan RMB, and the demand is expected to be even greater in the future.

[0003] The traditional method for preparing 1,5-pentanediol uses tetrahydrofurfuryl alcohol as a raw material and obtains it through multi-step catalytic hydrogenation, which usually requires a temperature as high as 300°C and a hydrogen pressure of 22-42 MPa. The currently reported catalyst design strategies include constructing hydrogenation active metal sites (such as Rh, Ir and Pt) near oxygenophilic sites (such as ReOx, MoOx and WOx) to obtain ideal adsorption geometry and reaction pathways.

[0004] Here, the preparation of 1,5-pentanediol from furfural is taken as an example, and the reaction process is shown as follows:

[0005]

[0006] In the above reaction process, furfural is first hydrogenated to obtain furfuryl alcohol (FFA), and then FFA is further hydrogenated in three ways: (1) FFA can be first hydrogenated to tetrahydrofurfuryl alcohol (THFA), and then further hydrogenated to 1,5-pentanediol (1,5-PeD) or 1,2-pentanediol (1,2-PeD), while the latter process requires overcoming a high reaction energy barrier due to the saturation of the tetrahydrofuran ring; (2) FFA can be first hydrogenated and dehydrated to 2-methylfuran (MF), and then further hydrogenated to 2-methyltetrahydrofuran (MTHF), which cannot achieve ring-opening reaction and thus cannot obtain the target product of terminal hydroxyl diol; and (3) FFA can be directly ring-opening hydrogenated to 1,5-PeD or 1,2-PeD, which avoids the saturation of the furan ring and has a lower reaction energy barrier; however, to achieve this reaction process, a specific catalyst needs to be used and the problem of improving the selectivity towards the target product 1,5-PeD needs to be solved.

[0007] In organic synthesis, regioselective reactions have always been an important way to achieve high selectivity of target products. However, this reaction usually needs to use noble metal as catalyst hydrogenation active site. In view of the existing application of furan ring catalytic ring-opening hydrogenation catalyst, the main challenge is that although the noble metal catalyst has higher hydrogenation activity, the ring-opening activity is not ideal, which leads to the need for further hydrogenation of the reaction molecule under ring saturation (such as using tetrahydrofurfuryl alcohol as the reaction substrate), thereby resulting in higher energy barrier of saturated ring-opening reaction, harsh reaction conditions (hydrogen pressure of 6-8 MPa, reaction time of 12-24 h), and lower conversion rate.

[0008] For non-noble metal catalysts, due to their moderate hydrogenation activity and excellent ring-opening ability, they can follow the reaction path of ring-opening first and then hydrogenation, so that the non-noble metal catalyst can realize one-pot catalytic ring-opening hydrogenation of furfural to 1,5-pentanediol. However, this process still faces the problem of excessive hydrogenation of furan ring leading to the generation of tetrahydrofurfuryl alcohol. Due to the limitation of hydrogenation activity of non-noble metal, it is difficult to further hydrogenate and open the saturated furan ring, which hinders the realization of high selectivity or high yield of 1,5-pentanediol.

[0009] In addition, the reaction process of preparing 1,6-hexanediol from 5-hydroxymethylfurfural is basically similar to the above process of preparing 1,5-pentanediol from furfural.

[0010]

[0011] In view of the requirements related to carbon neutralization target, and in the currently known literature reports, there is no report on the use of non-noble metal catalyst to catalyze the hydrogenation ring-opening of furan ring compounds to convert them into terminal hydroxyl diols with higher selectivity or yield. There is an increasingly urgent need to find a method for preparing terminal hydroxyl diols with high selectivity, low energy consumption and low carbon sustainability, especially a method for preparing non-noble metal catalysts that can reduce the high temperature and high pressure conditions of existing furan ring compound catalytic ring-opening hydrogenation and improve the selectivity or yield of linear diols. SUMMARY

[0012] The present application aims to solve the problems in the prior art, focuses on the further improvement of non-noble metal catalysts, adjusts the catalytic hydrogenation activity and ring-opening ability of non-noble metal catalysts to find a balance between the two, and provides a new method for preparing terminal hydroxyl linear diols by catalytic ring-opening hydrogenation of furan ring compounds. This method can obtain the target product with high selectivity or yield (more than 50%, preferably more than 60%).

[0013] To this end, the inventors discovered in their research that in the catalytic ring-opening hydrogenation reaction of furan ring compounds, when using an M-Fe bimetallic catalyst (i.e., a bimetallic supported catalyst M-Fe / support) obtained by doping non-noble metals Ni, Co, or Cu with a specific trace amount of inexpensive metal Fe and then loading it onto a metal oxide support, the added trace amount of metal Fe can provide more L acid sites for the catalyst and change the adsorption configuration of the furan ring, making the direct ring-opening process of the furan ring easier. At the same time, with the addition of metal Fe, the hydrogenation activity of non-noble metals can be suppressed to a certain extent, thereby suppressing the over-hydrogenation of the furan ring (such as suppressing the process from furfuryl alcohol to tetrahydrofurfuryl alcohol), so that the reaction follows a low-energy-barrier route of ring-opening followed by hydrogenation. Thus, it is possible to achieve highly selective ring-opening hydrogenation to obtain the target product of terminal hydroxyl straight-chain diol under milder conditions.

[0014] Furthermore, biomass-derived materials, such as lignocellulose, are among the most abundant renewable carbon resources in nature. Therefore, furan-cyclic compounds derived from lignocellulose, such as furfural and 5-hydroxymethylfurfural, are promising raw materials for the production of bio-based chemicals. This makes the process of catalytic ring-opening hydrogenation of furan-cyclic compounds to prepare terminal hydroxyl straight-chain diols such as 1,5-pentanediol or 1,6-hexanediol a low-carbon, green, and sustainable process. Therefore, the furan-cyclic compounds used in the method of this invention are preferably of biomass origin.

[0015] Based on this, the present invention provides a method for preparing terminal hydroxyl straight-chain diols from furan cyclic compounds via catalytic ring-opening hydrogenation. The method comprises, in the presence of a catalyst M-Fe / support supported on a non-noble metal M and trace amounts of metal Fe, subjecting the furan cyclic compound to a catalytic ring-opening hydrogenation reaction for 1-6 hours in an H2 atmosphere at 100-200°C, thereby obtaining the desired terminal hydroxyl straight-chain diol in a one-pot process with a yield of over 50%. The non-noble metal M and trace amounts of metal Fe are present in the catalyst M-Fe / support. Metal M is selected from Ni, Co, or Cu, the support is selected from Re2O7, MoO3, ZrO2, TiO2, Al2O3, CeO2, SiO2, or hydroxyapatite, and based on the total weight of catalyst M-Fe / support, the loading of the non-noble metal M is 1 to 10% by weight, and the loading of the trace metal Fe is 0.1 to 1% by weight, and the furan ring compound refers to a furan ring compound in which the furan ring is substituted by one or more substituents selected from aldehyde, hydroxyl, and hydroxymethyl groups.

[0016] In a preferred embodiment, the furan ring compound is derived from biomass.

[0017] In a preferred embodiment, the furan ring compound is furfural, furfuryl alcohol, 5-hydroxymethylfurfural, or 2,5-furandiethanol, and the terminal hydroxyl straight-chain diol is 1,5-pentanediol or 1,6-hexanediol.

[0018] In a preferred embodiment, the catalytic ring-opening hydrogenation reaction is carried out at a temperature of 100-150°C.

[0019] In a preferred embodiment, in the catalytic ring-opening hydrogenation reaction, the selectivity or yield of the terminal hydroxyl straight-chain diol is 60% or more.

[0020] In a preferred embodiment, the loading of the non-precious metal M is 3-9% by weight.

[0021] In a preferred embodiment, the catalyst M-Fe / support is prepared by the following method: a mixed salt aqueous solution containing soluble salts of metal M and metal Fe is added dropwise to the support or an aqueous solution containing the support in the required amount, and the mixture is thoroughly mixed under stirring. Then, an alkaline reagent is added to adjust the resulting solution to alkalinity to produce a precipitate. The precipitate is then obtained by centrifugation or filtration and subsequently dried to obtain a first catalyst precursor. The obtained first catalyst precursor is calcined in air at a temperature of 400–600°C to obtain a second catalyst precursor. The obtained second catalyst precursor is reduced with H2 at a temperature of 400–600°C for 1–4 h to obtain the desired bimetallic supported catalyst M-Fe / support containing trace amounts of metal Fe.

[0022] In a preferred embodiment, the alkaline reagent is selected from sodium hydroxide, ammonia, or potassium hydroxide.

[0023] In a preferred embodiment, the mixed salt solution is ultrasonically treated at a temperature of 40-60°C for 6-12 hours, and then added dropwise to a carrier or an aqueous solution containing the carrier.

[0024] This invention provides a novel method for preparing terminal hydroxyl straight-chain diols from furan ring compounds by catalytic ring-opening hydrogenation through the catalytic addition of trace amounts of inexpensive metal Fe to dope non-noble metals Ni, Co, or Cu, and then loading these doped metals onto a metal oxide support. This results in a trace Fe-modified M-Fe bimetallic catalyst (i.e., a bimetallic supported catalyst M-Fe / support). Compared to existing related technologies, the method of this invention not only enables the one-pot preparation of the desired terminal hydroxyl straight-chain diols under milder H2 pressure and lower temperature, but also achieves higher selectivity or yield for the target product.

[0025] Furthermore, the furan ring compounds used as raw materials in the method of the present invention can be of biomass origin, making the method of the present invention a low-energy, low-carbon, and sustainable method for preparing terminal hydroxyl diols. Attached Figure Description

[0026] Figure 1 The X-ray diffraction (XRD) patterns of Co-Fe / CeO2 catalysts with different Fe doping amounts prepared according to the method of the present invention are shown.

[0027] Figure 2 The diagram shows the H2-temperature programmed reduction (H2-TPR) of Co-Fe / CeO2 catalysts with different Fe doping amounts prepared according to the method of the present invention.

[0028] Figure 3 The X-ray diffraction (XRD) patterns of Ni-Fe / CeO2 and Cu-Fe / CeO2 catalysts prepared according to the method of the present invention are shown.

[0029] Figure 4 The X-ray diffraction (XRD) pattern of the Co-Fe / HAP catalyst prepared according to the method of the present invention is shown. Detailed Implementation

[0030] Given the weak hydrogenation activity of non-noble metal catalysts, the ring-opening hydrogenation reaction of furan rings requires high reaction temperatures, which easily triggers side reactions, leading to decreased selectivity of the ring-opening product. Furthermore, the catalyst stability is easily affected by multiple conditions. This invention recognizes that the readily available and inexpensive nature of non-noble metals, along with their moderate hydrogenation activity, allows the catalytic ring-opening hydrogenation reaction to follow a low-energy-barrier reaction route of ring-opening followed by hydrogenation. Further, through in-depth research, the inventors unexpectedly discovered that by using specific trace amounts of the inexpensive metal Fe to dope non-noble metals Ni, Co, or Cu, and then loading them onto a metal oxide support, a trace Fe-modified M-Fe bimetallic catalyst is constructed and can be used for the ring-opening hydrogenation reaction of furan ring compounds. Moreover, this trace Fe doping method utilizes metallic Fe to regulate and modify the hydrogenation performance of the main active metal M and the sites of the main active metal M, while simultaneously suppressing the saturated hydrogenation of the furan ring by the hydrogenating metal. This allows the use of such a bimetallic supported catalyst M-Fe / support to obtain the corresponding terminal hydroxyl straight-chain diols from furan ring compounds with high selectivity or high yield (overall above 50%, preferably above 60%) in a shorter reaction time at lower hydrogen pressure and reaction temperature. The trace Fe-tuned non-noble metal hydrogenation ring-opening catalyst proposed and innovatively provided by the inventors for the first time can selectively follow the reaction pathway of ring-opening followed by hydrogenation in the catalytic ring-opening hydrogenation reaction of furan ring compounds.

[0031] Based on the above research results, the method for preparing terminal hydroxyl straight-chain diols by catalytic ring-opening hydrogenation of furan ring compounds provided by the present invention includes reacting the furan ring compounds in the presence of a catalyst M-Fe / support supported with non-noble metal M and trace metal Fe, in an H2 atmosphere of 1-4 MPa, at a temperature of 100-200°C, preferably 120-160°C, for 1-6 h, preferably 2-4 h, to allow the furan ring compounds to undergo catalytic ring-opening hydrogenation, thereby obtaining the desired terminal hydroxyl straight-chain diol product in a one-pot process.

[0032] In this invention, furan ring compounds refer to furan ring-containing compounds in which the furan ring is substituted by one or more substituents selected from aldehyde, hydroxyl, and hydroxymethyl groups. Preferably, examples of such furan ring-containing compounds include, but are not limited to, furfural, furfuryl alcohol, 5-hydroxymethylfurfural, and 2,5-furandiethanol.

[0033] In this invention, the furan-cyclic compounds used as raw materials are preferably derived from biomass. For example, the raw material furan-cyclic compounds can be derived from lignocellulose in biomass. As mentioned above, using such biomass-derived furan-cyclic compounds as raw materials enables the low-energy, low-carbon, and sustainable preparation of terminal hydroxyl diol products.

[0034] In this invention, the terminal hydroxyl straight-chain diol of the target product refers to 1,5-pentanediol or 1,6-hexanediol.

[0035] In the catalyst M-Fe / support used in this invention, the non-noble metal M, which is the active metal, is selected from nickel (Ni), cobalt (Co), or copper (Cu).

[0036] In this invention, based on the total weight of the catalyst M-Fe / support used, the loading or content of the non-precious metal M is 1 to 10% by weight, and the loading or content of the trace metal Fe is 0.1 to 1% by weight. The inventors have discovered that by utilizing the combination of the aforementioned non-precious metal M loading and the aforementioned trace metal Fe loading, the desired terminal hydroxyl straight-chain diol product can be obtained with high selectivity or yield in a shorter time at lower hydrogen pressure and reaction temperature.

[0037] Conversely, on the one hand, if the loading of active metal M is too low (i.e., below 1%), even with trace Fe modification, the resulting supported catalyst will have insufficient activity for the ring-opening hydrogenation of furan ring-containing compounds. This not only leads to a low ring-opening reaction rate but also results in very low selectivity or yield of the target product, or even failure to obtain the target product. For example, when furfural is used as the reaction substrate, when the content of metal M is less than 1% by weight, under the reaction conditions required by this invention, the vast majority (e.g., more than 80%) of the product remains in furfuryl alcohol, rather than the desired 1,5-pentanediol. On the other hand, if the content of active metal M is higher than 10% by weight, it not only increases the cost of the catalyst itself but also does not significantly improve the catalytic activity of the catalyst. At the same time, it significantly reduces the modification effect of trace metal Fe, making it impossible to obtain the desired target product with the required high selectivity or yield. In addition, excessively high loading of metal M will also increase the particle size of the catalyst nanoparticles, leading to an increase in by-reaction products. Preferably, based on the total weight of the catalyst M-Fe / support used, the loading of the non-precious metal M is preferably 3 to 9% by weight. Such a loading can further ensure that, under the reaction conditions required by the present invention, the furan ring compound feedstock can be used to obtain the desired target product in a one-pot process with the required high selectivity or yield.

[0038] Furthermore, the loading or content of metallic iron in the catalyst of this invention is required to be trace amounts in the range of 0.1 to 1 wt%. Otherwise, on the one hand, if the content of the metal Fe used for modification is too low (i.e., below 0.1 wt%), the ring-opening process of the furan ring cannot be made easier because it cannot provide more L acid sites for the catalyst and sufficiently change the adsorption configuration of the furan ring, thus failing to achieve the desired modification effect; at the same time, the hydrogenation activity of the non-noble metal M cannot be appropriately suppressed, which may lead to over-hydrogenation, making it impossible to obtain the desired target product with the required high selectivity or yield. On the other hand, if the content of the metal Fe used for modification is too high (i.e., above 1 wt%), the excessive Fe will lead to further changes in the active sites or adsorption configuration, and due to excessive suppression, it will impair and / or dilute the catalytic hydrogenation activity of the main active metal M on the furan ring, while also increasing the particle size of the obtained catalyst nanoparticles, leading to an increase in by-products, which also makes it impossible to obtain the desired terminal hydroxyl straight-chain diol product in a one-pot process.

[0039] In the catalyst M-Fe / support of the present invention, the support is selected from rhenium oxide (Re₂O₇), molybdenum oxide (MoO₃), zirconium oxide (ZrO₂), titanium oxide (TiO₂), aluminum oxide (Al₂O₃), cerium oxide (CeO₂), and silicon oxide (SiO₂) or hydroxyapatite (HAP). The present invention has found that, for the combination of the above-mentioned non-noble metal M loading and the above-mentioned trace metal Fe loading, the supports selected from these materials can provide abundant anchoring sites for both metal M and trace Fe, and limit the size of the metal particles. They also provide abundant Brønsted acid and Lewis acid sites, thereby further enhancing the activity and stability of the catalyst.

[0040] In this invention, preferably, the average size of the support used is less than 100 nm, thereby providing a higher specific surface area to better exert the activity and stability of the catalyst.

[0041] In this invention, there are no special requirements for the equipment used for the catalytic ring-opening hydrogenation reaction of furan ring compounds. For example, a batch reactor such as a high-pressure reactor can be used.

[0042] Using the method of the present invention, in the catalytic ring-opening hydrogenation reaction of furan ring compounds, the selectivity or yield of terminal hydroxyl straight-chain diols can reach more than 50%, more preferably more than 60%.

[0043] In this invention, the catalyst M-Fe / support used can be obtained by the following method:

[0044] The first step involves mixing the soluble salts containing metal M and metal Fe in water, or directly mixing their respective aqueous solutions, in the required amounts. Then, the resulting mixed salt solution is added dropwise to the support or the aqueous solution containing the support and thoroughly mixed with stirring. An alkaline reagent is then added to adjust the resulting solution to alkalinity (e.g., adjusting the pH to around 10), thereby producing a precipitate. The precipitate is then obtained by centrifugation or filtration (e.g., vacuum filtration) and subsequently dried to obtain the first catalyst precursor.

[0045] The second step involves calcining the obtained first catalyst precursor in air at an elevated temperature (typically 400–600 °C) to obtain the second catalyst precursor.

[0046] The third step involves reducing the obtained second precursor with H2 at a temperature of 400–600 °C for 1–4 h to obtain the desired bimetallic supported catalyst containing trace amounts of Fe, namely M-Fe / support.

[0047] In the preparation of the catalyst of the present invention, the soluble salt of metal M or metal Fe refers to a salt that is soluble in an aqueous solvent such as water. For example, the soluble salt of metal M or metal Fe used can be a nitrate, a chloride salt, or other soluble salt, and preferably a nitrate thereof.

[0048] In the preparation of the catalyst of the present invention, preferably, the soluble salts of metal M and metal Fe can be mixed with water and ultrasonicated first, for example, the mixed salt aqueous solution can be ultrasonically treated at a temperature of 40-60°C for 2-12 hours, and then added dropwise to the support or an aqueous solution containing the support. More preferably, when mixing with the oxide support, the mixed salt aqueous solution can be added dropwise to the support or its aqueous solution.

[0049] In the preparation of the catalyst of the present invention, the alkaline reagent used can be selected from sodium hydroxide (NaOH), ammonia (NH3H2O), potassium hydroxide (KOH), etc. Furthermore, such alkaline reagents are typically or preferably provided in the form of their aqueous solutions.

[0050] In the preparation of the catalyst of the present invention, preferably, the concentration of the soluble salt of metal M in the mixed salt aqueous solution can be 10-150 mmol / L, and the concentration of the soluble salt of metal Fe can be 1-20 mmol / L. For example, it can be obtained by dissolving an appropriate amount of the soluble salt of metal M or Fe in an appropriate amount of water, such as 100 mL. With such concentrations of metal M and metal Fe, it is easier to obtain the catalyst with the corresponding loading.

[0051] In the preparation of the catalyst of the present invention, preferably, the metal M salt precursor and the metal Fe salt precursor can be ultrasonically mixed with water first, and then mixed with the support and stirred repeatedly.

[0052] In the preparation of the catalyst of the present invention, preferably, the solution obtained after mixing with the support can be treated at a temperature of 40-60°C for 2-12 hours in a round-bottom flask, for example.

[0053] In the preparation of the catalyst of the present invention, preferably, the precipitate obtained by centrifugation or filtration can be washed by centrifugation (e.g., washing by centrifugation three or more times in a 50 mL centrifuge tube) and then dried. More preferably, the washing is performed by centrifugation until the pH of the washing solution is 7, and then dried. The method of centrifugation washing is well known in the art.

[0054] In the preparation of the catalyst of the present invention, preferably, the obtained precipitate can be dried at a temperature of 80-110°C, more preferably for 2-12 hours, such as 4 hours, 6 hours, 8 hours or 10 hours.

[0055] In the catalyst preparation of this invention, the obtained first catalyst precursor can be ground and pulverized before calcination. For example, grinding and pulverization can be carried out in an agate mortar until it is ground into a fine powder, which is beneficial for subsequent calcination or heat treatment.

[0056] In the catalyst preparation of this invention, when calcining the catalyst in air, it is preferable to heat at a low heating rate (e.g., 1-2 °C / min) to avoid excessively large metal oxide particles caused by rapid temperature rise. More preferably, the calcination time can be 1-4 h, for example, 2 h. The inventors have discovered that a low heating rate can control the size of the metal particles and prevent excessive growth of the metal oxide particles. Simultaneously, calcination in air can convert metal M and metal Fe into their corresponding metal oxides, which is beneficial for subsequent hydrogen reduction. Furthermore, calcination treatment can enhance the interaction between the metal and the support.

[0057] In the catalyst preparation of this invention, preferably, the H2 reduction treatment can be carried out in a pure H2 atmosphere. For example, the reduction step can be performed in a pure hydrogen atmosphere for 2 hours, with the reduction temperature controlled at 400-600°C. This can adjust the ratio of the metal M and Fe oxides on the support to be reduced by H2, thereby exposing hydrogenation activity and ring-opening active sites to enhance the selectivity of the catalyst. Simultaneously, after reduction, M-Fe synergistic catalytic sites appear, further improving the ring-opening catalytic activity. By controlling the reduction temperature, a small amount of oxide support can interact with the metal sites, forming a metal-support interaction, while preventing the main part of the support from being reduced.

[0058] The present invention will now be described in detail by way of non-limiting examples (including examples of catalyst preparation and application). These examples are merely non-limiting illustrations of the specific implementation and process of the present invention, and are not intended to limit the scope of the present invention.

[0059] In the following embodiments, unless otherwise specified, the equipment, reagents, and raw materials used are commercially available and can be used directly without further processing after purchase. Similarly, unless otherwise specified, the reaction processes and processing methods involved are known in the art or are standard practice.

[0060] Preparation Example 1: Preparation of Catalyst 7Co-0.2Fe / CeO2

[0061] A 1000mL round-bottom flask equipped with a magnetic stirrer was placed in an oil bath (temperature set to 55℃). Under magnetic stirring, 12g of CeO2 (Shanghai Aladdin Biochemical Technology Co., Ltd.) and 600g of deionized water were poured into the flask. Then, 4.15g of cobalt nitrate hexahydrate (Co(NO3)2·6H2O) (Maclean's Reagent Co., Ltd.) and 0.174g of ferric nitrate nonahydrate (Fe(NO3)3·9H2O) (Sinopharm Chemical Reagent Co., Ltd.) were poured into a small beaker, and 100mL of water was added. The mixture was then sonicated until fully dissolved. The mixed salt solution in the small beaker was then slowly added dropwise to the solution in the round-bottom flask using a dropper, and stirring continued for 12 hours to allow the metal salts and carrier to fully contact and mix and reach equilibrium. Then, a diluted 0.5 mol / L ammonia solution (from Sinopharm Chemical Reagent Co., Ltd.) was slowly added dropwise to the above solution. A new precipitate was observed, and the pH of the solution was tested until it reached approximately 10 to ensure sufficient precipitation of the metal precursor. The mixture was then stirred and aged for 6 hours. Next, multiple centrifugal washings were performed until the pH of the washing solution was approximately 7. The precipitate obtained by centrifugation was then dried in a 100°C drying oven for 12 hours to obtain the first catalyst precursor.

[0062] Next, the obtained first catalyst precursor was ground into fine powder in a mortar and transferred to a ceramic crucible. Then, it was placed in a muffle furnace and heated to 500°C for 2 hours by programmed heating at a heating rate of 1°C / min to obtain the second catalyst precursor.

[0063] Finally, in a sealed tube furnace under a hydrogen atmosphere, the obtained second catalyst precursor was reduced with pure H2 (gas tank from Nanjing Special Gases Co., Ltd.) for 2 hours by heating to 500°C at a programmed heating rate of 1°C / min, thereby obtaining the desired catalyst. Based on the amount of metal precursor added during stirring and mixing, the loading of Co was calculated to be 7 wt% and the loading of Fe was 0.2 wt% based on the total weight of the catalyst; accordingly, this catalyst is denoted as 7Co-0.2Fe / CeO2.

[0064] Figure 1 The image shows the XRD patterns of the catalyst 7Co-0.2Fe / CeO2 and the support CeO2 obtained by Preparation Example 1. Figure 1 It can be seen that the diffraction peaks are those of the carrier CeO2, as shown in the standard card PDF#34-0394 for CeO2.

[0065] Figure 2 The image shows the H2-TPR diagram of the catalyst 7Co-0.2Fe / CeO2 obtained by Preparation Example 1. From... Figure 2It can be seen that within the selected temperature range, as the reduction temperature increases, the first reduction peak is the peak of Co3O4 being reduced to CoO, and then CoO is reduced to metallic Co; at the same time, due to the addition of trace amounts of Fe, no obvious Fe reduction peak was found.

[0066] Preparation Example 2-10: Preparation of Other Co-Fe / CeO2 Catalysts with Different Metal Loadings

[0067] By varying the amounts of Co(NO3)2·6H2O and Fe(NO3)3·9H2O added, and following the same procedure as in Preparation Example 1 above, the following catalysts were prepared: 7Co-0.1Fe / CeO2, 7Co-0.3Fe / CeO2, 7Co-0.4Fe / CeO2, 7Co-0.7Fe / CeO2, 7Co-1Fe / CeO2, 1Co-0.2Fe / CeO2, 3Co-0.2Fe / CeO2, 5Co-0.2Fe / CeO2, and 9Co-0.2Fe / CeO2.

[0068] The XRD patterns of the catalysts obtained above, specifically 7Co-0.1Fe / CeO2 and 7Co-0.3Fe / CeO2, are also... Figure 1 As shown in the image. Figure 1 As can be seen, similar to the catalyst 7Co-0.2Fe / CeO2 obtained in Preparation Example 1, neither of these catalysts showed obvious diffraction peaks of metal Co and Fe, and the peaks that appeared were mainly diffraction peaks of the support CeO2. Figure 1 These results indicate that increasing the Fe doping level from 0.1% to 0.3% did not result in the formation of large particles of Co or Fe metal or their corresponding oxides.

[0069] Preparation Examples 11-17: Preparation of M-Fe / CeO2 catalysts with different metals M and different metal loadings

[0070] The catalyst was prepared by changing the type of metal M and / or the amount of soluble salt of metal Fe, following the same procedure as in Preparation Example 1 above.

[0071] A 1000mL round-bottom flask equipped with a magnetic stirrer was placed in an oil bath (temperature set to 55℃). Under magnetic stirring, 12g of CeO2 (Shanghai Aladdin Biochemical Technology Co., Ltd.) and 500g of deionized water were added to the flask. Then, 4.16g of nickel nitrate hexahydrate (Ni(NO3)2·6H2O) (Maclean's Reagent Co., Ltd.) or 3.19g of copper nitrate trihydrate (Cu(NO3)2·3H2O), along with the corresponding amounts of ferric nitrate nonahydrate (Fe(NO3)3·9H2O) (Sinopharm Chemical Reagent Co., Ltd.), were added to a small beaker with 100mL of water and sonicated to dissolve thoroughly. Subsequently, the mixed salt solution in the small beaker was slowly added dropwise to the solution in the round-bottom flask using a dropper, and stirring continued for 12 hours to ensure thorough contact and mixing of the metal salts and the carrier, reaching equilibrium. Then, a diluted 0.5 mol / L ammonia solution (from Sinopharm Chemical Reagent Co., Ltd.) was slowly added dropwise to the above solution. A new precipitate was observed, and the pH of the solution was tested until it reached approximately 10 to ensure sufficient precipitation of the metal precursor. The mixture was then stirred and aged for 6 hours. Next, multiple centrifugal washings were performed until the pH of the washing solution was approximately 7. The precipitate obtained by centrifugation was then dried in a 100°C drying oven for 12 hours to obtain the first catalyst precursor.

[0072] Next, the obtained first catalyst precursor was ground into fine powder in a mortar and transferred to a ceramic crucible. Then, it was placed in a muffle furnace and heated to 500°C for 2 hours by programmed heating at a heating rate of 1°C / min to obtain the second catalyst precursor.

[0073] Finally, in a sealed tube furnace under a hydrogen atmosphere, the obtained second catalyst precursor was reduced with pure H2 (Nanjing Special Gases Co., Ltd.) for 2 hours by heating to 500°C at a programmed heating rate of 1°C / min, thereby obtaining the desired catalyst. Based on the total weight of the catalyst and the corresponding loadings of various main active metals and Fe, the following catalysts were obtained: 7Ni-0.1Fe / CeO2, 7Ni-0.2Fe / CeO2, 7Ni-0.3Fe / CeO2, 7Ni-0.4Fe / CeO2, 7Cu-0.1Fe / CeO2, 7Cu-0.2Fe / CeO2, and 7Cu-0.3Fe / CeO2.

[0074] Figure 3 The XRD diffraction patterns of 7Ni-0.3Fe / CeO2 and 7Cu-0.2Fe / CeO2 are shown. Figure 3 It can be seen that neither of these catalysts has obvious diffraction peaks of metals Ni, Cu and Fe, and the peaks that appear are mainly diffraction peaks of the support CeO2.

[0075] Preparation Examples 18-32: Preparation of M-Fe / supported catalysts with different metal species M, different metal loadings, and different supports

[0076] Following the same procedure as in Preparation Examples 1-17 above, by supporting appropriate amounts of iron (Fe) precursor salt and appropriate amounts of nickel (Ni), copper (Cu), and cobalt (Co) precursor salt on 12 g of Re₂O₇, MoO₃, ZrO₂, TiO₂, Al₂O₃, CeO₂, SiO₂, or hydroxyapatite (HAP) support, the following catalysts were prepared: 7Co-0.2Fe / Re₂O₇, 7Ni-0.4Fe / Re₂O₇, 7Co-0.2Fe / MoO₃, 7Ni -0.3Fe / MoO3, 7Co-0.2Fe / TiO2, 7Ni-0.2Fe / TiO2, 7Co-0.2Fe / ZrO2, 5Co-0.2Fe / ZrO2, 7Co-0.2Fe / Al2O3, 9Cu-0.3Fe / Al2O3, 7Co-0.2Fe / SiO2, 9Ni-0.2Fe / SiO2, 7Co-0.2Fe / HAP, 7Ni-0.3Fe / HAP and 7Cu-0.2Fe / HAP.

[0077] Figure 4 The XRD diffraction pattern of the obtained catalyst 7Co-0.2Fe / HAP is shown. Figure 4 It can be seen that the diffraction peaks are mainly composed of the carrier HAP itself.

[0078] Application Example 1: Preparation of 1,5-pentanediol by catalytic ring-opening hydrogenation of furfural

[0079] In a 1L high-pressure reactor (Anhui Kemi Instruments) equipped with a stirrer and heating device, 600mL of anhydrous ethanol (Sinopharm Chemical Reagent Co., Ltd.) was added as a solvent. Then, 3.840g of furfural (Shanghai Aladdin Biochemical Technology Co., Ltd., purified by vacuum distillation and stored in a refrigerator) and 1.600g of the catalyst 7Co-0.2Fe / CeO2 prepared in Preparation Example 1 were added. The reactor was then first charged with 2MPa of H2 and then discharged (repeated 4 times) to purge the air inside. Next, 3.5MPa of H2 was added, and finally the H2 pressure was adjusted to a stable 3MPa. The reactor was then heated to 130℃ for 4 hours with stirring. After the reaction was complete, the heating mantle was removed, and the reactor was allowed to cool naturally to room temperature. The reactor was then opened, and the mixture was filtered under reduced pressure to separate the catalyst from the reaction solution. The obtained reaction solution was diluted with ethanol, and 2.000 g of n-hexanol (Shanghai Aladdin Biochemical Technology Co., Ltd.) was added as an internal standard. The solution was then analyzed by gas chromatography (GC1690).

[0080] The gas chromatography conditions were as follows: GC1690 gas chromatograph with FID detector, capillary column (Innowax, 30m × 0.250mm × 0.25μm), programmed temperature rise, with the initial column temperature set at 65℃, increasing to 250℃ at a rate of 10℃ / min and holding for 10 minutes. The carrier gas was 99.99% high-purity N2, with a flow rate of 1mL / min.

[0081] As mentioned above, intermediates and / or byproducts detected in the reaction of furfural to 1,5-pentanediol (1,5-Ped) include furfuryl alcohol (FFA), tetrahydrofurfuryl alcohol (THFA), 2-methylfuran (MF), 2-methyltetrahydrofuran (MTHF), 1,2-pentanediol (1,2-Ped), and other byproducts.

[0082] The reactant conversion rate and product selectivity were calculated based on the gas chromatography detection results, as shown in Table 1.

[0083] Application Example 2-17: Preparation of 1,5-pentanediol by catalytic ring-opening hydrogenation of furfural

[0084] Except for using the catalysts obtained in Preparation Examples 2-17 and the reaction conditions shown in Table 1, the reaction of furfural-catalyzed ring-opening hydrogenation to 1,5-pentanediol was carried out according to the same procedure described in Application Example 1. After the reaction, the reactant conversion and product selectivity were calculated based on the gas chromatography results, and the results are shown in Table 1.

[0085] Table 1

[0086]

[0087] *Reaction conditions: Temperature 130℃, time 4h, H2 pressure 3MPa;

[0088] **Reaction conditions:** Temperature 140℃, time 4h, H2 pressure 3MPa;

[0089] ***Reaction conditions: temperature 150℃, time 4h, H2 pressure 4MPa.

[0090] ****Reaction conditions: Temperature 160℃, Time 6h, H2 pressure 4Mpa.

[0091] As can be seen from the results in Table 1, using the method of the present invention, under milder reaction conditions than the prior art (specifically: temperature 130-160℃, time 4-6h, H2 pressure 3-4MPa), the reactant furfural can be converted at a conversion rate of almost 100%, and the selectivity (corresponding production rate) of the target product 1,5-pentanediol is above 50%, and some even reach above 70%.

[0092] Application Examples 18-32: Preparation of 1,5-pentanediol from furfural-catalyzed ring-opening hydrogenation

[0093] Except for using the catalysts obtained in Preparation Examples 18-32 and the reaction conditions shown in Table 1, the reaction of furfural-catalyzed ring-opening hydrogenation to 1,5-pentanediol was carried out according to the same procedure described in Application Example 1. After the reaction, the reactant conversion and product selectivity were calculated based on the gas chromatography results, and the results are shown in Table 2.

[0094] Table 2

[0095]

[0096] *Reaction conditions: Temperature 130℃, time 4h, H2 pressure 3MPa;

[0097] **Reaction conditions:** Temperature 120℃, time 3h, H2 pressure 2MPa;

[0098] ***Reaction conditions: Temperature 140℃, Time 4h, H2 pressure 3MPa.

[0099] As can be seen from the results in Table 2, using the method of the present invention, under significantly milder reaction conditions than the prior art (specifically: temperature 120-140℃, time 3-4h, H2 pressure 2-3MPa), the reactant furfural can be converted at a 100% conversion rate, and the selectivity (corresponding production rate) of the target product 1,5-pentanediol is above 50%.

[0100] Application Examples 33-37: Preparation of 1,6-hexanediol from 5-hydroxymethylfurfural ring-opening hydrogenation

[0101]

[0102] In a 1L high-pressure reactor (Anhui Kemi Instruments) equipped with a stirrer and heating device, 600mL of anhydrous ethanol was added as a solvent, along with 5.044g of the reaction substrate 5-hydroxymethylfurfural (Shanghai Aladdin Biochemical Technology Co., Ltd., purified by vacuum distillation and stored in a refrigerator) and 1.600g of the catalysts prepared in the preparation example: 7Co-0.2Fe / CeO2 or 7Ni-0.3Fe / CeO2, 9Cu-0.3Fe / Al2O3, 7Co-0.2Fe / HAP, and 7Ni-0.3Fe / MoO3. Then, 2MPa of H2 was first introduced into the reactor and then discharged (repeated 4 times) to purge the internal air. Next, 3.5MPa of H2 was introduced, and finally, the H2 pressure was adjusted to a stable 3MPa. The reactor was then heated to 150℃ for 4 hours with stirring. After the reaction was complete, the heating mantle was removed, and the reactor was allowed to cool naturally to room temperature. The reactor was then opened, and the mixture was filtered under reduced pressure to separate the catalyst from the reaction liquid. The obtained reaction solution was diluted with ethanol, and 2.000 g of n-hexanol was added as an internal standard. The solution was then analyzed by gas chromatography.

[0103] The gas chromatography conditions were as follows: GC1690 gas chromatograph with FID detector, capillary column (Innowax, 30m × 0.250mm × 0.25μm), programmed temperature rise, with the initial column temperature set at 65℃, increasing to 250℃ at a rate of 10℃ / min and holding for 10 minutes. The carrier gas was 99.99% high-purity N2, with a flow rate of 1mL / min.

[0104] As is known, intermediates and / or byproducts present in the reaction of 5-hydroxymethylfurfural to 1,6-hexanediol include 2,5-furandiethanol, 2,5-dihydroxymethyltetrahydrofurfural alcohol, and other byproducts.

[0105] The reactant conversion rate and product selectivity were calculated based on the gas chromatography detection results, as shown in Table 3.

[0106] Table 3

[0107]

[0108] *Reaction conditions: Temperature 140℃, time 4h, H2 pressure 3MPa;

[0109] **Reaction conditions:** Temperature 130℃, time 4h, H2 pressure 2MPa;

[0110] ***Reaction conditions: temperature 120℃, time 3h, H2 pressure 3Mpa.

[0111] As can be seen from the results in Table 3, using the method of the present invention, under significantly milder reaction conditions than the prior art (specifically: temperature 120-140℃, time 3-4h, H2 pressure 3-4MPa), the reactant 5-hydroxymethylfurfural can be converted at a 100% conversion rate, and the selectivity (corresponding production rate) of the target product 1,6-hexanediol is above 50%.

[0112] The results in Tables 1-3 above demonstrate that this invention, using a non-noble metal supported catalyst M-Fe / support (where metal M is Ni, Co, or Cu) adjusted by trace amounts of Fe, achieves a one-pot preparation of terminal hydroxyl linear diols from furan cyclic compounds with higher selectivity or yield under significantly milder conditions than existing techniques. The process is simple and convenient. Furthermore, the catalyst used in this invention is inexpensive, readily available, and magnetic, allowing for easy separation and recycling from the product, thus giving this invention broad application prospects.

[0113] The above embodiments are merely intended to illustrate the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand and implement the present invention, and do not limit the scope of protection. Any modifications, equivalent substitutions, or improvements made according to the technical solutions of the present invention are within the scope of the claims of the present invention.

Claims

1. A method for producing a terminal hydroxyl linear diol by catalytic ring-opening hydrogenation of a furan ring compound, the method comprising subjecting the furan ring compound to catalytic ring-opening hydrogenation in the presence of a catalyst M-Fe / support loaded with a non-noble metal M and a trace metal Fe, in a H2 atmosphere of 1 to 4 MPa, at a temperature of 100 to 200°C for 1 to 6 hours, thereby obtaining the desired terminal hydroxyl linear diol in one pot at a yield of 50% or more, wherein in the catalyst M-Fe / support, the non-noble metal M is selected from Ni, Co or Cu, the support is selected from Re2O7, MoO3, ZrO2, TiO2, Al2O3, CeO2, SiO2 or hydroxyapatite, and the loading amount of the non-noble metal M is 1 to 10% by weight and the loading amount of the trace metal Fe is 0.1 to 1% by weight, based on the total weight of the catalyst M-Fe / support, and wherein the furan ring compound refers to a furan ring-containing compound in which a furan ring is substituted with one or more substituents selected from an aldehyde group, a hydroxyl group and a hydroxymethyl group. The furan ring compound is derived from biomass. The furan ring compound is furfural, furfuryl alcohol, 5-hydroxymethylfurfural or 2,5-furandimethanol, and the terminal hydroxyl linear diol is 1,5-pentanediol or 1,6-hexanediol.

2. The method of claim 1, wherein, The catalytic ring-opening hydrogenation reaction is performed at a temperature of 100 to 150°C.

3. The method according to claim 1 or 2, characterized in that, In the catalytic ring-opening hydrogenation reaction, the selectivity or yield of the terminal hydroxyl linear diol is 60% or more.

4. The method according to claim 1 or 2, characterized in that, The loading amount of the non-noble metal M is 3 to 9% by weight.

5. The method according to claim 1 or 2, characterized in that, The catalyst M-Fe / support is prepared by the following method:

6. The method of claim 1 or 2, wherein, A mixed salt aqueous solution containing a soluble salt of the metal M and a soluble salt of the metal Fe is added dropwise to a support or an aqueous solution containing the support in a desired amount, and mixed well with stirring, and then a basic reagent is added to adjust the resulting solution to be basic to produce a precipitate, and then the precipitate is obtained by centrifugation or filtration, followed by drying to obtain a first catalyst precursor; 7. The method of claim 1 or 2, wherein, The obtained first catalyst precursor is calcined in air at a temperature of 400 to 600°C to obtain a second catalyst precursor; The obtained second catalyst precursor is reduced with H2 at a temperature of 400 to 600°C for 1 to 4 hours to obtain the desired bimetallic supported catalyst M-Fe / support containing the trace metal Fe. The basic reagent is selected from sodium hydroxide, aqueous ammonia or potassium hydroxide. The mixed salt aqueous solution is subjected to ultrasonic treatment at a temperature of 40 to 60°C for 6 to 12 hours, and then added dropwise to the support or the aqueous solution containing the support.

8. The method of claim 7, wherein, The mixed salt aqueous solution is subjected to ultrasonic treatment at a temperature of 40 to 60°C for 6 to 12 hours, and then added dropwise to the support or the aqueous solution containing the support.

9. The method of claim 7, wherein, ​

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