A process for the preparation of tetrahydrofurfuryl alcohol

Abstract

The present application relates to a kind of tetrahydrofurfuryl alcohol preparation method, which includes the following steps: in the presence of catalyst, furfural and hydrogen are contacted and reacted;The catalyst includes the composite of nickel and silicon dioxide, wherein, nickel is crystal structure, and silicon dioxide is amorphous structure.The present application uses the composite of crystalline nickel and amorphous silicon dioxide as catalyst to catalyze furfural hydrogenation, so that the whole reaction process has less side reaction, and conversion and yield are relatively high, can realize tetrahydrofurfuryl alcohol stable, continuous and efficient production, and has important significance to bio-chemical industry, medicine and health and other fields.

Description

Technical Field

[0001] This invention relates to the field of organic chemistry, and specifically to a method for preparing tetrahydrofurfuryl alcohol. Background Technology

[0002] Tetrahydrofurfuryl alcohol can be used to prepare chemicals such as succinic acid, pentanediol, and tetrahydrofuran; it is also used as a solvent in coatings, resins, and oils; and as a lubricant and dispersant in the printing and dyeing industry. Therefore, the continuous and efficient production of tetrahydrofurfuryl alcohol is of great significance to the fields of biochemical engineering, medicine, and healthcare.

[0003] Currently, tetrahydrofurfuryl alcohol is mainly obtained by Raney Ni-catalyzed hydrogenation, as shown in Formula I below. Patent CN104610199B uses Pd / TiO2 catalysis to prepare tetrahydrofurfuryl alcohol, exhibiting good catalytic activity; however, the use of precious metals results in high costs. Patents CN105693659B, CN109529946B, CN109647429B, CN109647472B, and CN106622219B all employ a furfural aqueous-phase hydrogenation method, which suffers from solvent separation and easy loss of catalyst metal. Based on this background, this invention aims to achieve efficient and continuous preparation of tetrahydrofurfuryl alcohol using a novel catalyst.

[0004]

[0005] It should be noted that the information disclosed in the foregoing background section is only used to enhance the understanding of the background of the present invention, and therefore may include information that does not constitute prior art known to those skilled in the art.

[0006] Overcoming the shortcomings of the aforementioned catalysts and using a better catalyst to catalyze furfural and hydrogen to produce tetrahydrofurfuryl alcohol stably and efficiently is a pressing technical problem that needs to be solved. Summary of the Invention

[0007] A primary objective of this invention is to overcome at least one of the deficiencies of the prior art and provide a method for preparing tetrahydrofurfuryl alcohol, thereby addressing the problems of high catalyst cost, harsh reaction conditions, and difficulty in achieving stable and efficient catalytic hydrogenation reactions to prepare tetrahydrofurfuryl alcohol.

[0008] This invention relates to a method for preparing tetrahydrofurfuryl alcohol, comprising the following steps: reacting furfural and hydrogen in the presence of a catalyst; wherein the catalyst comprises a composite of nickel and silicon dioxide, wherein nickel is crystalline and silicon dioxide is amorphous.

[0009] Optionally, the catalyst contains 1 wt% to 60 wt% nickel and 40 wt% to 99 wt% silica, based on the mass of the catalyst.

[0010] Optionally, the catalyst is a porous structure composed of nickel grains and silica particle clusters; the nickel grains have a grain size of 0.5 nm to 10 nm, and the silica particle clusters have a size of 200 nm to 500 nm; the catalyst has a specific surface area of ​​200 m². 2 / g~500m 2 / g, with a pore volume of 0.2cc / g to 0.7cc / g.

[0011] Optionally, the catalyst is prepared by the following steps: adding an alkali to a first system containing a nickel source, a silicon source and water to obtain a second system; and reducing the solid material obtained from the second system.

[0012] Optionally, the nickel source is selected from one or more of basic nickel carbonate, nickel nitrate, nickel sulfate, nickel chloride, and nickel acetate; the silicon source is selected from one or more of water glass, silica sol, and tetraethyl orthosilicate; and the alkali is selected from one or more of sodium hydroxide, potassium hydroxide, ammonia, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, and ammonium carbonate.

[0013] Optionally, the solid material is prepared by the following steps: allowing the second system to stand, filtering out the solid, drying, and calcining.

[0014] Optionally, the preparation method further includes the following steps before the reduction treatment: mixing the solid material from the second system with the additives and molding; preferably, it further includes drying and calcining after molding.

[0015] Optionally, the molding process is selected from one or more of extrusion, tableting, ball rolling, and granulation; preferably, when the molding is extrusion, the mechanical strength of the catalyst is 10 N / mm to 30 N / mm; when the molding is tableting, the mechanical strength of the catalyst is 10 N / particle to 100 N / particle.

[0016] Optionally, the molding is an extrusion strip, and the additives include a first binder, a pore-forming agent, and water; the mass ratio of the solid material, the first binder, the pore-forming agent, and water when mixed is 1:(0.02~50):(0~0.1):(0.05~0.4).

[0017] Optionally, the first binder is selected from one or more of water glass, silica sol and tetraethyl orthosilicate, and the pore-forming agent is selected from one or more of guar gum powder, graphite powder, starch and citric acid.

[0018] Optionally, the molding is a tableting process, and the additives include a second binder; the mass ratio of the solid material and the second binder when mixed is 1:(0.005~0.2); the second binder is selected from one or more of guar gum powder, starch and graphite powder.

[0019] Optionally, the contact reaction is carried out in a fixed-bed reactor at a reaction temperature of 10℃ to 200℃, a hydrogen pressure of 0.1MPa to 10MPa, and a mass hourly space velocity of 0.1h. -1 ~50h -1 The volume ratio of hydrogen to furfural is 50 to 2000.

[0020] Optionally, the contact reaction is carried out in a high-pressure reactor at a reaction temperature of 10℃ to 200℃, a hydrogen pressure of 0.1MPa to 10MPa, a reaction time of 0.1h to 10h, a stirring speed of 400r / min to 1000r / min, and a mass ratio of catalyst to furfural of 1:(1 to 50).

[0021] Beneficial effects:

[0022] This invention uses a composite of crystalline nickel and amorphous silica as a catalyst to catalyze the hydrogenation of furfural, resulting in fewer side reactions and higher conversion and yield rates. It enables the stable, continuous, and efficient production of tetrahydrofurfuryl alcohol, which is of great significance for fields such as biochemical engineering and pharmaceuticals. Attached Figure Description

[0023] Figure 1 The XRD patterns of the nickel-silicon composite oxide and catalyst in Example 1 are shown below.

[0024] Figure 2 The XRD patterns are those of the nickel-silicon composite oxide of Example 1 and the catalyst in the oxidation state of Comparative Example 1.

[0025] Figure 3A This is a TEM image of the catalyst from Example 1;

[0026] Figure 3B TEM image of the catalyst in Comparative Example 1;

[0027] Figure 4A Here is a SEM image of the catalyst from Example 1;

[0028] Figure 4B This is a SEM image of the catalyst in Comparative Example 1. Detailed Implementation

[0029] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. Through these descriptions, the features and advantages of the present application will become clearer and more apparent.

[0030] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments. Although various aspects of embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated otherwise.

[0031] Furthermore, the technical features involved in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0032] This invention relates to a method for preparing tetrahydrofurfuryl alcohol, comprising the following steps: reacting furfural and hydrogen in the presence of a catalyst; wherein the catalyst comprises a composite of nickel and silicon dioxide, wherein nickel is crystalline and silicon dioxide is amorphous.

[0033] It should be noted that furfural and hydrogen undergo a catalytic hydrogenation reaction under the catalysis of the catalyst, converting furfural into tetrahydrofurfuryl alcohol. The presence of crystalline nickel and amorphous silica in the catalyst ensures the stable and efficient hydrogenation reaction of furfural.

[0034] According to one embodiment of the present invention, the catalyst contains 1 wt% to 60 wt% nickel and 40 wt% to 99 wt% silicon dioxide, based on the mass of the catalyst.

[0035] Preferably, the nickel content is 5 wt% to 40 wt%, and the silicon dioxide content is 60 wt% to 95 wt%.

[0036] According to one embodiment of the present invention, the catalyst is a porous structure formed by the aggregation of nickel grains and silica particle clusters; the grain size of the nickel grains is 0.5 nm to 10 nm, and the size of the silica particle clusters is 200 nm to 500 nm; the specific surface area of ​​the catalyst is 200 m². 2 / g~500m 2 / g, with a pore volume of 0.2cc / g to 0.7cc / g.

[0037] It should be noted that, as Figure 4A As shown, the composite catalyst has a porous structure composed of nickel grains and silica oxide particle clusters, which are irregularly distributed among themselves. The specific surface area of ​​this catalyst is preferably 200 m². 2 / g~380m 2 / g, for example 220m 2 / g、240m 2 / g、300m 2 / g、320m 2 / g, etc.; the pore volume is preferably 0.3cc / g to 0.6cc / g, for example 0.37cc / g, 0.40cc / g, 0.42cc / g, 0.44cc / g, 0.45cc / g, etc. As can be seen from the foregoing, this catalyst has a specific porous cluster aggregation structure, which is beneficial to increasing the specific surface area of ​​the catalyst in contact with the reactants, thereby improving the catalytic activity.

[0038] It should be noted that the catalyst, which includes a composite of nickel and silicon dioxide, can be Ni-(SiO2). a The value of 'a' ranges from 0.1 to 40. For example, 'a' can be 2.1, 3, 3.2, 4.5, 5, 6.7, 6.8, 6.9, 7, 7.1, 10, 10.8, 11, 13.9, and 14. In some embodiments, 'a' is preferably 2.9 to 11.1.

[0039] According to one embodiment of the present invention, the catalyst is prepared by the following steps: adding an alkali to a first system containing a nickel source, a silicon source and water to obtain a second system; and reducing the solid material obtained from the second system.

[0040] Tetrahydrofurfuryl alcohol is a high-value-added fine chemical. Currently, noble metal catalysts are often used to catalyze the hydrogenation reaction of furfural to prepare tetrahydrofurfuryl alcohol. However, these catalysts suffer from problems such as high cost, solvent separation, and easy loss of metals in the aqueous phase. The inventors of this invention have discovered that a nickel-silica composite prepared by co-precipitation can be used as a catalyst for the hydrogenation reaction of furfural. This composite exhibits high activity and stability, and is easy to separate, showing promising application prospects.

[0041] It should be noted that the hydrogenation catalyst of the present invention is prepared by a specific co-precipitation method. Specifically, the first system can be a mixture containing nickel ions and silicon-containing solid phases such as silica sol particles, wherein the molar concentration of nickel ions in the first system can be 0.1-5.0 mol / L, and the molar concentration of silicon source in the first system can be 0.1-20 mol / L. The alkali can be added to the first system in the form of an aqueous solution of alkali, wherein the molar concentration of the aqueous solution of alkali can be 0.1-5.0 mol / L, and the pH value of the second system (if it is a mixture) is adjusted to 8-14 by adding alkali.

[0042] It should be noted that after adding alkali to the first system, the nickel source, silicon source, and alkali form a precipitate, which is then reduced to obtain the catalyst. The precipitate may contain silicon oxide and nickel silicate, etc.

[0043] In a preferred embodiment, a first system, also known as a mixed solution, is prepared by mixing a nickel source, a silicon source, and water. The alkali is added to the first system in the form of an aqueous solution. Specifically, the first system is kept under stirring, and the aqueous solution of the alkali is slowly added to the first system to generate a precipitate. The reaction temperature for generating the precipitate can be 0°C to 60°C. Then, stirring is continued for 0-6 hours. That is, stirring is optional.

[0044] According to one embodiment of the present invention, the nickel source is selected from one or more of basic nickel carbonate, nickel nitrate, nickel sulfate, nickel chloride, and nickel acetate; the silicon source is selected from one or more of water glass, silica sol, and tetraethyl orthosilicate; and the alkali is selected from one or more of sodium hydroxide, potassium hydroxide, ammonia, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, and ammonium carbonate.

[0045] It should be noted that the nickel source can be a soluble nickel source, and the silicon source can be a soluble silicon source.

[0046] According to one embodiment of the present invention, the solid material is prepared by the following steps: allowing the second system to stand, filtering out the solid, drying and calcining.

[0047] It should be noted that the solid material, namely nickel-silicon composite oxide, is obtained by allowing the second system to stand, filtering out the solid phase, drying, and calcining. Specifically, the standing time can be 6-12 hours at 0℃~60℃, preferably 8-12 hours, to allow the nickel source, silicon source, and alkali in the second system to fully react into a precipitate, which is then allowed to stand. The drying temperature can be 100℃~120℃, and the drying time can be 2 hours~24 hours; the calcination temperature can be 300℃~700℃, and the calcination time can be 2 hours~6 hours.

[0048] The reduction treatment of the solid material obtained from the second system can be carried out at a temperature of 400℃ to 600℃ for 2 hours to 6 hours, and the reduction treatment can be carried out under a hydrogen atmosphere. As another embodiment, the nickel-silicon composite oxide can be obtained by allowing the second system to stand, filtering out the solid, and drying, without the need for calcination.

[0049] The structure of the nickel-silicon composite oxide is a porous structure formed by the aggregation of amorphous silicon oxide and crystalline nickel oxide particles. The size of the nickel oxide grains in the nickel-silicon composite oxide is roughly equivalent to the size of the nickel metal grains in the catalyst; at the same time, they have similar structures and their pore structure parameters are also approximately equivalent.

[0050] According to a preferred embodiment of the present invention, the preparation method further includes the following steps before the reduction treatment: mixing the solid material from the second system with the additives and molding; preferably, it further includes drying and calcining after molding.

[0051] According to the preferred embodiment of the present invention, the molding process is selected from one or more of extrusion, tableting, balling, and granulation; preferably, when the molding is extrusion, the mechanical strength of the catalyst is 10 N / mm to 30 N / mm; when the molding is tableting, the mechanical strength of the catalyst is 10 N / particle to 100 N / particle.

[0052] It should be noted that the molding process described in this invention includes, but is not limited to, one or more of the following: extrusion, ball rolling, tableting, and granulation.

[0053] According to a first preferred embodiment of the present invention, the molding is an extrusion strip, and the additives include a first binder, a pore-forming agent, and water; the mass ratio of the solid material, the first binder, the pore-forming agent, and water when mixed is 1:(0.02~50):(0~0.1):(0.05~0.4).

[0054] It should be noted that the mass of the solid material, the first binder, the pore-forming agent and water when they are mixed is calculated on a dry basis.

[0055] It should be noted that when the forming is in the form of extrusion, the solid material from the second system is mixed with the additives, and after forming, a strip-shaped material from the extruder is obtained. This strip is then pelletized, dried, and calcined before undergoing the reduction treatment. In this embodiment, the drying temperature can be 100℃~130℃, and the time can be 2h~24h; the calcination temperature can be 300℃~700℃, and the time can be 2h~6h; the reduction treatment temperature can be 400℃~600℃, and the time can be 2h~6h. The composite material formed by crystalline nickel and amorphous silicon dioxide obtained through the reduction treatment is the catalyst.

[0056] According to a first embodiment of the present invention, the first binder is selected from one or more of water glass, silica sol and tetraethyl orthosilicate, and the pore-forming agent is selected from one or more of guar gum powder, graphite powder, starch and citric acid.

[0057] The catalyst obtained through the aforementioned extrusion process is a strip-shaped catalyst, specifically including cylindrical, clover-shaped, or butterfly-shaped forms. The cross-sectional dimensions of the strip-shaped catalyst can range from 0.5 mm to 3 mm, for example, 1 mm, 1.5 mm, 2 mm, 2.5 mm, etc., where the cross-sectional dimensions refer to the dimensions in all directions of the strip-shaped catalyst's cross-section being within the range of 0.5 to 3 mm. Furthermore, the length of the strip-shaped catalyst can range from 0.2 cm to 0.8 cm. Generally, after the aforementioned treatment, the mechanical strength of the obtained strip-shaped catalyst is 10 N / mm to 30 N / mm, for example, 10 N / mm, 12 N / mm, 15 N / mm, 22 N / mm, 24 N / mm, 25 N / mm, 30 N / mm, etc.

[0058] According to a second preferred embodiment of the present invention, the molding is tableting, and the additive includes a second binder; the mass ratio of the solid material and the second binder when mixed is 1:(0.005~0.2); the second binder is selected from one or more of guar gum powder, starch, and graphite powder. Preferably, the binder is graphite powder. The mass of the solid material and the second binder when mixed is calculated on a dry basis, and the mass ratio can also be 1:0.00625, 1:0.008, 1:0.01, 1:0.03, 1:0.05, 1:0.08, 1:0.1, 1:0.12, 1:0.15, 1:0.18, etc.

[0059] It should be noted that when the forming process is tableting, drying and calcination can also be performed to carry out the reduction treatment. The drying temperature after tableting is 110℃~130℃, 2h~24h, and the calcination temperature is 400℃~600℃, for example, 450℃, 500℃, 550℃; the time is 2h~6h.

[0060] The material after tableting is calcined and then subjected to reduction treatment. The reduction temperature is 400℃~600℃, for example, 450℃, 500℃, or 550℃, and the time is 2h~6h. The reducing agent can be hydrogen. The catalyst of this invention is obtained through reduction treatment. After the aforementioned series of treatments, the catalyst obtained after tableting is in granular or flake form with a cross-sectional size of 1mm to 5mm. Generally, the larger the size, the greater its resistance. The mechanical strength is 10N / particle to 100N / particle, and can be further 20 to 60N / particle, such as 12N / particle, 15N / particle, 20N / particle, 25N / particle, 27.3N / particle, 30N / particle, 35N / particle, 38.9N / particle, 40N / particle, 45N / particle, 45.7N / particle, 50N / particle, 55N / particle, 60N / particle, 62.4N / particle, 65N / particle, 70N / particle, 80N / particle, 90N / particle, 95N / particle, etc.

[0061] According to one embodiment of the present invention, the contact reaction is carried out in a fixed-bed reactor at a reaction temperature of 10°C to 200°C, a hydrogen pressure of 0.1 MPa to 10 MPa, and a mass hourly space velocity of 0.1 h⁻¹. -1 ~50h -1 The volume ratio of hydrogen to furfural is 50 to 2000.

[0062] When the contact reaction is carried out in a fixed-bed reactor, specifically, furfural is dissolved in water (or solvent-free) and then contacted with the catalyst in the fixed-bed reactor, and the reaction is carried out under the action of hydrogen. The reaction temperature is 10℃ to 200℃, for example, 20℃, 40℃, 60℃, 70℃, 75℃, 80℃, 90℃, 100℃, 103℃, 110℃, 116℃, 124℃, 136℃, 141℃, 159℃, 168℃, 180℃, 190℃, etc. Optionally, the reaction temperature is 40℃ to 160℃. The hydrogen pressure is 0.1MPa to 10MPa, for example, 0.2MPa, 0.7MPa, 1MPa, 2MPa, 3.5MPa, 4MPa, 5MPa, 6MPa, 7MPa, 8MPa, 9MPa, 10MPa, etc., optionally, 2MPa to 7MPa. Mass hourly space velocity is 0.1 h. -1 ~50h -1 For example, 0.1h -1 0.5h -1 1h -1 2h -1 4h -1 10h -1 25h -1 37h -1 45h -1 50h -1 The hydrogen / furfural volume ratio is 50–2000, for example, 100, 220, 350, 490, 550, 760, 880, 1000, 1600, 2000, etc.

[0063] According to one embodiment of the present invention, the contact reaction is carried out in a high-pressure reactor at a reaction temperature of 10°C to 200°C, a hydrogen pressure of 0.1 MPa to 10 MPa, a reaction time of 0.1 h to 10 h, a stirring speed of 400 r / min to 1000 r / min, and a mass ratio of catalyst to furfural of 1:(1 to 50).

[0064] When the contact reaction is carried out in a high-pressure reactor, specifically, furfural is dissolved in water (or solvent-free), then placed in the high-pressure reactor, and a catalyst is added to the reactor. The catalyst contacts the furfural and is stirred, and the reaction takes place under the action of hydrogen. The reaction temperature is 10℃~200℃, for example, 20℃, 40℃, 60℃, 70℃, 75℃, 80℃, 90℃, 100℃, 103℃, 110℃, 116℃, 124℃, 136℃, 141℃, 159℃, 168℃, 180℃, 190℃, etc. Optionally, the reaction temperature is 40℃~160℃. The hydrogen pressure is 0.1 MPa to 10 MPa, for example, 0.2 MPa, 0.7 MPa, 1 MPa, 2 MPa, 3.5 MPa, 4 MPa, 5 MPa, 6 MPa, 7 MPa, 8 MPa, 9 MPa, 10 MPa, etc., preferably 2 MPa to 7 MPa. The reaction time is 0.1 h to 10 h, for example, 0.1 h, 0.5 h, 1 h, 2 h, 4 h, 10 h, etc., optionally 0.5 h to 4 h. The stirring speed is 400 r / min to 1000 r / min, for example, 400 r / min, 500 r / min, 670 r / min, 800 r / min, 950 r / min, 1000 r / min, etc.; the mass ratio of catalyst to furfural is 1:(1 to 50), for example, 1:10, 1:20, 1:25, 1:30, 1:35, 1:40, 1:45, 1:50, etc.

[0065] As can be seen, the preparation of tetrahydrofurfuryl alcohol using the catalyst of this invention has relatively mild reaction conditions and low cost. It is applicable to both fixed-bed reactors and high-pressure reactors.

[0066] The present invention will be further illustrated by the following examples, but the invention is not limited thereto. Unless otherwise specified, all raw materials used are commercially available.

[0067] The XRD characterization of the present invention was performed using a Rigaku Electric Industries, Ltd. D max-2600PC X-ray diffractometer. The test conditions were: Cu target Kα rays, scanning rate 5° / min, scanning range 10°~80°, step size 0.02°, tube current 100mA, tube voltage 40kV.

[0068] The SEM characterization of this invention was performed using a FEI Quan TA-400F scanning electron microscope with a scanning voltage of 20 kV.

[0069] The TEM characterization of this invention was performed using a Tecnai G2 F20 S-TWIN transmission electron microscope from FEI, with an accelerating voltage of 200 kV.

[0070] The qualitative and quantitative analysis of the materials of this invention was performed using the mass spectrometer and flame ionization detector of an Agilent 5977A-7890B gas chromatography-mass spectrometry system.

[0071] The molar ratio and mass content of the present invention were calculated according to the XRF characterization method, and the total pore volume and specific surface area were measured by nitrogen adsorption-desorption characterization.

[0072] In the following examples, the catalyst strength of the strip catalyst refers to the radial strength (i.e., the direction through the axis in the radial plane) of the strip catalyst; the strength is measured using a mechanical strength tester.

[0073]

[0074] In this invention, the strength of the catalyst after tableting refers to the pressure at which each catalyst particle is crushed; the strength is measured using a mechanical strength tester.

[0075] In the following examples, the furfural conversion rate was quantitatively calculated by liquid chromatography, and the tetrahydrofurfuryl alcohol yield was calculated by gas chromatography using the peak area normalization method.

[0076]

[0077]

[0078] Example 1

[0079] 290g of Ni(NO3)2·6H2O and 1600g of silica sol (30% solid content) were weighed and dissolved in deionized water to prepare solution a with a concentration of 1.0 mol / L (based on Ni ions). A 1.0 mol / L sodium hydroxide solution b was prepared. While keeping solution a stirred, solution b was slowly added to solution a until the pH of the system reached 10.5. After the addition was complete, stirring was continued for 1 hour, then stirring was stopped, and the mixture was allowed to stand for 8 hours. The precipitate was then filtered and washed until neutral. The filter cake was dried in a forced-air drying oven at 110℃ for 12 hours, and then calcined in a muffle furnace at 500℃ for 3 hours to obtain nickel-silicon composite oxide.

[0080] 160.0g of nickel-silicon composite oxide, 140.0g of silica sol (30% solid content), 1.0g of citric acid, 10.0g of guar gum powder and 40.0g of water were mixed evenly and kneaded repeatedly. The mixture was then extruded into cylindrical strips with a diameter of 1.8mm using an extruder. The strips were then cut into strips with a length of 3-5mm, dried at 120℃ for 4h, and calcined at 500℃ for 4h. Finally, the strip catalyst was reduced with hydrogen at 400℃ for 3h, and its mechanical strength was 18.9N / mm.

[0081] Figure 1 The XRD patterns of the nickel-silicon composite oxide and the catalyst in Example 1 are shown respectively. Figure 1 It can be seen that neither the nickel-silicon composite oxide nor the catalyst exhibits obvious SiO2 diffraction characteristic peaks, indicating that SiO2 exists in an amorphous structure. Furthermore, the nickel-silicon composite oxide shows NiO diffraction characteristic peaks, indicating that NiO exists in a crystalline structure; the catalyst in Example 1 shows Ni diffraction characteristic peaks, indicating that Ni also exists in a crystalline structure.

[0082] 3g of the above catalyst was used for solvent-free hydrogenation of furfural in a fixed-bed reactor; the reaction temperature was 80℃, the pressure was 3MPa, and the mass hourly space velocity (HHSV) was 0.8h. -1 The hydrogen / furfural volume ratio was 800. Ultimately, the catalyst operated continuously for 600 hours without a significant decrease in catalytic activity, achieving an average furfural conversion rate of 99.1% and an average tetrahydrofurfural yield of 98.6%.

[0083] Example 2

[0084] 145g of Ni(NO3)2·6H2O and 1600g of silica sol (30% solid content) were weighed and dissolved in deionized water to prepare solution a with a concentration of 1.0 mol / L (based on Ni ions). A 1.0 mol / L sodium hydroxide solution b was prepared. While keeping solution a stirred, solution b was slowly added to solution a until the pH of the system reached 10.5. After the addition was complete, stirring was continued for 1 hour, then stirring was stopped, and the mixture was allowed to stand for 8 hours. The precipitate was then filtered and washed until neutral. The filter cake was dried in a forced-air drying oven at 110℃ for 12 hours, and then calcined in a muffle furnace at 500℃ for 3 hours to obtain nickel-silicon composite oxide.

[0085] 160.0g of nickel-silicon composite oxide, 140.0g of silica sol (30% solid content), 1.0g of citric acid, 10.0g of guar gum powder and 40.0g of water were mixed evenly and kneaded repeatedly. The mixture was then extruded into cylindrical strips with a diameter of 1.8mm using an extruder. The strips were then cut into strips with a length of 3-5mm, dried at 120℃ for 4 hours, and calcined at 500℃ for 4 hours. Finally, the strip catalyst was reduced with hydrogen at 400℃ for 3 hours, and its mechanical strength was 17.4N / mm.

[0086] 3g of the above catalyst was used to carry out the hydrogenation reaction of furfural in a fixed-bed reactor, with water as the solvent and furfural mass fraction of 30%; the reaction temperature was 80℃, the pressure was 3MPa, and the mass hourly space velocity was 0.8h. -1 The hydrogen / furfural volume ratio was 800. Ultimately, after 400 hours of continuous catalyst operation, the average furfural conversion rate was 98.5%, and the average yield of tetrahydrofurfural was 97.8%.

[0087] Example 3

[0088] 435g of Ni(NO3)2·6H2O and 1600g of silica sol (30% solid content) were weighed and dissolved in deionized water to prepare solution a with a concentration of 1.0 mol / L (based on Ni ions). A 1.0 mol / L sodium hydroxide solution b was prepared. While keeping solution a stirred, solution b was slowly added to solution a until the pH of the system reached 10.5. After the addition was complete, stirring was continued for 1 hour, then stirring was stopped, and the mixture was allowed to stand for 8 hours. The precipitate was then filtered and washed until neutral. The filter cake was dried in a forced-air drying oven at 110℃ for 12 hours, and then calcined in a muffle furnace at 500℃ for 3 hours to obtain nickel-silicon composite oxide.

[0089] 160.0g of nickel-silicon composite oxide, 140.0g of silica sol (30% solid content), 10.0g of guar gum powder and 40.0g of water were mixed evenly and kneaded repeatedly. The mixture was then extruded into butterfly-shaped strips with a diameter of 2.0mm using an extruder. The strips were then cut into strips with a length of 3-5mm, dried at 120℃ for 4h, and calcined at 500℃ for 3h. Finally, the strip catalyst was reduced with hydrogen at 400℃ for 3h, and its mechanical strength was 19.6N / mm.

[0090] 3g of the above catalyst was used to carry out solvent-free hydrogenation of furfural in a fixed-bed reactor; the reaction temperature was 90℃, the pressure was 3MPa, and the mass hourly space velocity (H₂S₀) was 0.8h. -1 The hydrogen / furfural volume ratio was 800. Ultimately, the catalyst operated continuously for 800 hours without a significant decrease in catalytic activity, achieving an average furfural conversion rate of 98.9% and an average tetrahydrofurfural yield of 98.4%.

[0091] Example 4

[0092] 290g of Ni(NO3)2·6H2O and 1600g of silica sol (30% solid content) were weighed and dissolved in deionized water to prepare solution a with a concentration of 1.0 mol / L (based on Ni ions). A 1.0 mol / L sodium hydroxide solution b was prepared. While keeping solution a stirred, solution b was slowly added to solution a until the pH of the system reached 10.5. After the addition was complete, stirring was continued for 1 hour, then stirring was stopped, and the mixture was allowed to stand for 8 hours. The precipitate was then filtered and washed until neutral. The filter cake was dried in a forced-air drying oven at 110℃ for 12 hours, and then calcined in a muffle furnace at 500℃ for 3 hours to obtain nickel-silicon composite oxide.

[0093] 160.0g of nickel-silicon composite oxide, 140.0g of silica sol (30% solid content), 1.0g of citric acid, 10.0g of guar gum powder and 40.0g of water were mixed evenly and kneaded repeatedly. The mixture was then extruded into cylindrical strips with a diameter of 1.8mm using an extruder. The strips were then cut into strips with a length of 3-5mm, dried at 120℃ for 4h, and calcined at 500℃ for 4h. Finally, the strip catalyst was reduced with hydrogen at 400℃ for 3h, and its mechanical strength was 18.9N / mm.

[0094] 3g of the above catalyst was used to carry out the hydrogenation reaction of furfural in a fixed-bed reactor, with water as the solvent and furfural mass fraction of 10%; the reaction temperature was 120℃, the pressure was 3MPa, and the mass hourly space velocity was 1h. -1 The hydrogen / furfural volume ratio was 800. Ultimately, after 500 hours of continuous operation, the catalytic activity did not decrease significantly, with an average furfural conversion rate of 97.9% and an average tetrahydrofurfural yield of 97.0%.

[0095] Example 5

[0096] 290g of Ni(NO3)2·6H2O and 1600g of silica sol (30% solid content) were weighed and dissolved in deionized water to prepare solution a with a concentration of 1.0 mol / L (based on Ni ions). A 1.0 mol / L sodium hydroxide solution b was prepared. While keeping solution a stirred, solution b was slowly added to solution a until the pH of the system reached 10.5. After the addition was complete, stirring was continued for 1 hour, then stirring was stopped, and the mixture was allowed to stand for 8 hours. The precipitate was then filtered and washed until neutral. The filter cake was dried in a forced-air drying oven at 110℃ for 12 hours, and then calcined in a muffle furnace at 500℃ for 3 hours to obtain nickel-silicon composite oxide.

[0097] 160.0g of nickel-silicon composite oxide and 5.0g of graphite powder were mixed evenly and pressed into cylindrical sheets with a diameter of 3.0mm using a tablet press. The sheets were dried at 120℃ for 4 hours and calcined at 500℃ for 4 hours. Finally, the catalyst was obtained by hydrogen reduction at 400℃ for 3 hours, with a mechanical strength of 33.2N / particle.

[0098] 3g of the above catalyst was used to carry out solventless hydrogenation of furfural in a fixed-bed reactor at a reaction temperature of 120℃, a pressure of 5MPa, and a mass hourly space velocity of 1h. -1 The hydrogen / furfural volume ratio was 800. Ultimately, after 1000 hours of continuous operation, the catalytic activity did not significantly decrease, with an average furfural conversion rate of 98.6% and an average tetrahydrofurfural yield of 98.1%.

[0099] Example 6

[0100] 290g of Ni(NO3)2·6H2O and 1600g of silica sol (30% solid content) were weighed and dissolved in deionized water to prepare solution a with a concentration of 1.0 mol / L (based on Ni ions). A 1.0 mol / L sodium hydroxide solution b was prepared. While keeping solution a stirred, solution b was slowly added to solution a until the pH of the system reached 10.5. After the addition was complete, stirring was continued for 1 hour, then stirring was stopped, and the mixture was allowed to stand for 8 hours. The precipitate was then filtered and washed until neutral. The filter cake was dried in a forced-air drying oven at 110℃ for 12 hours, and then calcined in a muffle furnace at 500℃ for 3 hours to obtain nickel-silicon composite oxide.

[0101] 1.0 g of nickel-silicon composite oxide was placed in a tube furnace and reduced at 500 °C with a hydrogen flow rate of 30 mL / min for 3 h to obtain Ni@SiO2 catalyst.

[0102] 0.2 g of the above Ni@SiO2 catalyst was used to carry out a solventless hydrogenation reaction of furfural in a high-pressure reactor; the mass ratio of catalyst to furfural was 1:10; the reaction temperature was 80℃, the stirring speed was 600 r / min, the pressure was 4 MPa, and the reaction time was 1 h. Ultimately, the furfural conversion rate was 98.7%, and the tetrahydrofurfuryl alcohol yield was 98.4%.

[0103] The catalyst after the reaction was recovered by centrifugation and reused in the hydrogenation experiment, repeated 8 times. Specific experimental results are shown in Table 1. As can be seen from Table 1, after each reaction using the reused catalyst, the sample was a transparent liquid. GC-MS analysis showed that the feed conversion rate was over 98% and the molar yield of tetrahydrofurfuryl alcohol was over 97%.

[0104] Table 1

[0105]

[0106]

[0107] Example 7

[0108] 290g of Ni(NO3)2·6H2O and 1600g of silica sol (30% solid content) were weighed and dissolved in deionized water to prepare solution a with a concentration of 1.0 mol / L (based on Ni ions). A 1.0 mol / L sodium hydroxide solution b was prepared. While keeping solution a stirred, solution b was slowly added to solution a until the pH of the system reached 10.5. After the addition was complete, stirring was continued for 1 hour, then stirring was stopped, and the mixture was allowed to stand for 8 hours. The precipitate was then filtered and washed until neutral. The filter cake was dried in a forced-air drying oven at 110℃ for 12 hours, and then calcined in a muffle furnace at 500℃ for 3 hours to obtain nickel-silicon composite oxide.

[0109] 160.0g of nickel-silicon composite oxide and 40.0g of water were mixed evenly and kneaded repeatedly. The mixture was then extruded into cylindrical strips with a diameter of 1.8mm using an extruder. The strips were then cut into strips with a length of 3-5mm, dried at 120℃ for 4 hours, and calcined at 500℃ for 4 hours. Finally, the strip catalyst was reduced with hydrogen at 400℃ for 3 hours, and its mechanical strength was 5.9N / mm.

[0110] 3g of the above catalyst was used to carry out solvent-free hydrogenation of furfural in a fixed-bed reactor at a reaction temperature of 80℃, a pressure of 3MPa, and a mass hourly space velocity of 0.8h. -1The hydrogen / furfural volume ratio was 800. The initial conversion rate of furfural was 98.6%, and the initial yield of tetrahydrofurfural was 97.2%. Due to insufficient catalyst mechanical strength, bed blockage occurred, and the fixed-bed reaction could not operate for an extended period.

[0111] Comparative Example 1

[0112] 480g of SiO2 was weighed as a support, and 290g of Ni(NO3)2·6H2O was dissolved in water. The solution was then impregnated onto the weighed SiO2 support in equal volume. After uniform impregnation, the solution was dried in a forced-air drying oven at 100℃ for 12h, then calcined in a muffle furnace at 500℃ for 4h, and then reduced in a hydrogen reduction furnace at 400℃ for 3h to obtain the catalyst.

[0113] 3g of the above catalyst was used for solvent-free hydrogenation of furfural in a fixed-bed reactor at a reaction temperature of 80℃, a pressure of 3MPa, and a mass hourly space velocity of 0.8h. -1 The hydrogen / furfural volume ratio was 800. The initial conversion rate of furfural was only 81.6%, and the initial yield of tetrahydrofurfural was 48.2%.

[0114] Figure 2 XRD characterization patterns of the nickel-silicon composite oxide (i.e., the catalyst before reduction) of Example 1 and the oxidized catalyst of Comparative Example 1 (i.e., the catalyst of Comparative Example 1 before reduction) are shown respectively. The XRD results show that the oxidized catalyst of Comparative Example 1 prepared by the impregnation method has obvious SiO2 diffraction characteristic peaks, indicating that SiO2 in the oxidized catalyst of Comparative Example 1 has a crystalline structure; while the SiO2 in the nickel-silicon composite oxide prepared by the co-precipitation method of Example 1 exists in an amorphous structure. Furthermore, both the nickel-silicon composite oxide and the oxidized catalyst of Comparative Example 1 exhibit NiO diffraction characteristic peaks, indicating that NiO exists in a crystalline structure; moreover, the NiO diffraction characteristic peaks of the oxidized catalyst of Comparative Example 1 prepared by the impregnation method are sharper. Generally, the sharper the diffraction peak, the larger the grain size. Therefore, the oxidized catalyst of Comparative Example 1 has larger NiO particles as its active component. With a comparable total active component loading, the catalyst of Comparative Example 1 with larger active metal particles is not conducive to catalytic activity, indirectly demonstrating the superiority of the catalyst preparation method in this invention.

[0115] Figure 3A This is a TEM image of the catalyst from Example 1. Figure 3B This is a TEM image of the catalyst in Comparative Example 1. From... Figure 3A and Figure 3B It can be seen that Ni in the catalyst of Comparative Example 1 has lattice stripes and the Ni grain size is relatively large; while the active component Ni in the catalyst of Example 1 has a particle size of about 4 nm and is more uniformly distributed, which verifies the above XRD characterization results.

[0116] Figure 4A This is a SEM image of the catalyst from Example 1. Figure 4B This is a SEM image of the catalyst in Comparative Example 1. From... Figure 4A and Figure 4B It can be seen that the catalyst of Example 1 prepared by the coprecipitation method has a loose structure, which is composed of small particle clusters and is arranged irregularly, with the cluster size between 200 and 500 nm; while the catalyst of Comparative Example 1 prepared by the impregnation method is composed of larger crystal particle clusters and is also arranged irregularly, with the cluster size between 500 and 1500 nm.

[0117] As can be seen from the results of Example 1 and Comparative Example 1, in the catalyst prepared by the co-precipitation method of the present invention, silicon dioxide exists in an amorphous structure and nickel exists in a crystalline structure. Moreover, the nickel grains are small and uniformly distributed, which makes the catalyst highly active and thus helps to improve the conversion rate of catalytic hydrogenation reaction.

[0118] Test Example 1

[0119] The total pore volume, specific surface area, and mechanical strength of the catalysts obtained in Examples 1-7 and Comparative Example 1 were tested respectively. The results and the mass fraction of Ni in the catalysts are detailed in Table 2 below.

[0120] Table 2

[0121]

[0122]

[0123] As shown in Table 2, the catalyst prepared by the co-precipitation method of this invention has a specific porous clustered structure, which is beneficial to increasing the specific surface area of ​​the catalyst in contact with the reactants, thereby improving the catalytic activity. Furthermore, after molding treatment, the catalyst also possesses high mechanical strength and can be used in fixed-bed reactors for continuous production. When applied to the preparation of tetrahydrofurfuryl alcohol, this catalyst exhibits high catalytic activity and stability, with a yield of tetrahydrofurfuryl alcohol generally exceeding 97%, demonstrating promising application prospects.

[0124] This invention obtains a nickel-silica composite catalyst using the aforementioned co-precipitation method. This method is simple, low-cost, and environmentally friendly, as it uses virtually no organic solvents. Furthermore, the mechanical strength of the composite is further improved through molding treatment. When applied to hydrogenation reactions in fixed-bed reactors, it effectively avoids bed blockage caused by catalyst breakage, enabling continuous reaction operation and reducing production costs and operational complexity. Simultaneously, the catalyst's activity and stability are not reduced after molding treatment. Applying this catalyst to the preparation of tetrahydrofurfuryl alcohol (THE) demonstrates advantages such as low cost, mild reaction conditions, high feed conversion rate, and high THE yield, showing promising industrial application prospects.

[0125] In the description of this application, it should be noted that the terms "upper", "lower", "inner", "outer", "front", "rear", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship in the working state of this application. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0126] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0127] The present application has been described above with reference to preferred embodiments; however, these embodiments are merely exemplary and illustrative. Various substitutions and modifications can be made to the present application based on these embodiments, all of which fall within the protection scope of the present application.

Claims

1. A method for preparing tetrahydrofurfuryl alcohol, characterized in that, Includes the following steps: In the presence of a catalyst, furfural and hydrogen are brought into contact and reacted. The catalyst comprises a composite of nickel and silicon dioxide, wherein the nickel has a crystalline structure and the silicon dioxide has an amorphous structure. The catalyst is prepared by the following steps: Adding an alkali to the first system containing a nickel source, a silicon source, and water yields the second system. The second system is allowed to stand, the solid phase is filtered out, dried and calcined to obtain the solid phase material; The solid material from the second system is mixed with the additives, shaped, and then dried and calcined. The catalyst is obtained by reduction treatment after drying and calcination.

2. The preparation method according to claim 1, characterized in that, The catalyst contains 1 wt% to 60 wt% nickel and 40 wt% to 99 wt% silica, based on the mass of the catalyst.

3. The preparation method according to claim 1 or 2, characterized in that, The catalyst is a porous structure in which nickel crystal grains and silica particle clusters are aggregated, the grain size of the nickel crystal grains is 0.5 nm to 10 nm, the size of the silica particle clusters is 200 nm to 500 nm, the specific surface area of the catalyst is 200 m 2 / g to 500 m 2 / g, and the pore volume is 0.2 cc / g to 0.7 cc / g.

4. The preparation method according to claim 1, characterized in that, The nickel source is selected from one or more of basic nickel carbonate, nickel nitrate, nickel sulfate, nickel chloride, and nickel acetate; the silicon source is selected from one or more of water glass, silica sol, and tetraethyl orthosilicate; the alkali is selected from one or more of sodium hydroxide, potassium hydroxide, ammonia, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, and ammonium carbonate.

5. The preparation method according to claim 1, characterized in that, The molding process is selected from one or more of extrusion, tableting, ball rolling, and granulation.

6. The preparation method according to claim 5, characterized in that, When the molding is in the form of an extrusion bar, the mechanical strength of the catalyst is 10 N / mm to 30 N / mm; when the molding is in the form of a tablet, the mechanical strength of the catalyst is 10 N / tablet to 100 N / tablet.

7. The preparation method according to claim 5, characterized in that, The molding process is an extrusion strip, and the additives include a first binder, a pore-forming agent, and water; The mass ratio of the solid material, the first binder, the pore-forming agent and water when they are mixed is 1:(0.02-50):(0-0.1):(0.05-0.4).

8. The preparation method according to claim 7, characterized in that, The first binder is selected from one or more of water glass, silica sol and tetraethyl orthosilicate, and the pore-forming agent is selected from one or more of guar gum powder, graphite powder, starch and citric acid.

9. The preparation method according to claim 5, characterized in that, The molding process is a tablet compression, and the additives include a second binder; The mass ratio of the solid material and the second binder during the mixing process is 1:(0.005~0.2). The second binder is selected from one or more of guar gum powder, starch and graphite powder.

10. The preparation method according to claim 1, characterized in that, The contact reaction is carried out in a fixed-bed reactor at a temperature of 10℃ to 200℃, a hydrogen pressure of 0.1 MPa to 10 MPa, and a mass hourly space velocity of 0.1 h⁻¹. -1 ~50h -1 The volume ratio of hydrogen to furfural is 50 to 2000.

11. The preparation method according to claim 1, characterized in that, The contact reaction is carried out in a high-pressure reactor at a temperature of 10℃ to 200℃, a hydrogen pressure of 0.1MPa to 10MPa, a reaction time of 0.1h to 10h, a stirring speed of 400r / min to 1000r / min, and a mass ratio of catalyst to furfural of 1:(1~50).

Images