A Ni-Sn / TiO2 catalyst, its preparation method and application

Abstract

This invention discloses a Ni-Sn / TiO2 catalyst, its preparation method, and its application, belonging to the field of catalyst synthesis technology. The catalyst includes a TiO2 support and a Ni-Sn intermetallic compound supported on the TiO2 support. The molar ratio of Sn to Ni in the Ni-Sn intermetallic compound is 0.5:1 to 2:1. The Ni-Sn intermetallic compound contains Ni. 2.7 Sn2 phase, Ni3Sn4 phase, and Ni 2.7 A mixed phase of Sn2 and Ni3Sn4 phases. This invention employs the above-mentioned Ni-Sn / TiO2 catalyst, its preparation method, and its application. By using an inexpensive Ni-Sn system, the catalyst cost is significantly reduced. A specific sequential impregnation method is used in combination with a TiO2 support and an optimized Sn / Ni ratio to prepare a highly dispersed specific Ni-Sn intermetallic compound under relatively mild conditions.

Description

Technical Field

[0001] This invention relates to the field of catalyst synthesis technology, and in particular to a Ni-Sn / TiO2 catalyst, its preparation method, and its application. Background Technology

[0002] The selective hydrogenation of α,β-unsaturated aldehydes to unsaturated alcohols is an important reaction in the fine chemical industry. Citral, as a typical inexpensive and readily available α,β-unsaturated aldehyde, has hydrogenation products nerol and geraniol, which possess unique rose aromas and antitumor and antibacterial bioactivities, and are widely used in the preparation of fragrances and flavorings and the synthesis of pharmaceutical intermediates. Natural extraction methods suffer from low purification rates and difficulties in large-scale production. Heterogeneous catalytic hydrogenation is the preferred process due to its high atom economy, easy product separation, and mild reaction conditions. However, because C=C bonds are thermodynamically and kinetically more readily hydrogenated than C=O bonds, traditional single-metal hydrogenation catalysts typically produce saturated aldehydes as the main product, making it difficult to achieve highly selective preparation of unsaturated alcohols. Intermetallic compounds, due to their special electronic and geometric structures, exhibit unique advantages in selective hydrogenation reactions.

[0003] Currently, research on catalysts for the selective hydrogenation of citral to prepare nerol and geraniol mainly focuses on noble metal systems, non-noble metal systems, and intermetallic compound systems. Regarding noble metal catalysts, Chinese patent CN105618095B discloses a porous nano-silicon carbide-supported platinum catalyst, achieving a 69% selectivity for citric acid at an 80.4% conversion of citral. This catalyst uses the noble metal platinum, resulting in high production costs and room for improvement in the selectivity of the target product. Chinese patent CN115337936A discloses a PtCo / C catalyst, achieving a 92.7% selectivity for citric acid at a 98.4% conversion of citral. This catalyst still relies on the noble metal platinum, making large-scale industrial application difficult. Chinese patent CN1... Patent 01747152A discloses a Pt / Fe2O3 catalyst prepared by coprecipitation, achieving a citral conversion rate of 14.2% and an unsaturated alcohol selectivity of 58.9%. However, this catalyst not only uses the precious metal platinum but also exhibits low catalytic activity and target product selectivity. Chinese patent CN110922298A discloses supported Pd, Ru, and Rh precious metal catalysts using activated carbon and molecular sieves as supports, achieving better conversion rates and selectivity. However, it requires the addition of protic acid promoters, increasing process complexity and cost, and the core active component remains a precious metal. Regarding non-precious metal catalysts, Chinese patent CN116854562A discloses a homogeneous catalyst composed of nickel or copper salts and organic ligands, enabling the hydrogenation of citral to nerol and geraniol. However, the homogeneous catalytic system suffers from difficulties in product separation and high operating costs, and the reaction requires the addition of acid and base promoters, which does not conform to the principles of green chemistry. Regarding intermetallic compound systems, existing technologies disclose zeolite-supported monometallic Ni and bimetallic Ni-Sn catalysts, with Ni loading at 8.1-9.2 wt% and Sn loading at 0.46 wt%. These catalysts exhibit extremely low selectivity for the target products nerol and geraniol, increasing only from 0.9% to 6.3% for monometallic catalysts, which cannot meet the requirements for industrial applications. Additionally, existing technologies have prepared bulk Ni3Sn and Ni3Sn2 intermetallic compound catalysts via an electric arc furnace molten element mixture method. However, the catalysts prepared by this method have large particle sizes, poor catalytic activity, and require harsh reaction conditions.

[0004] It is evident that most high-performance catalysts rely on precious metals such as Pt, Ir, and Ru, resulting in high production costs and hindering large-scale industrial application. Non-precious metal homogeneous catalysts suffer from difficulties in product separation, high operating costs, and the need to add acid and alkali additives, which does not align with the principles of green chemistry. Furthermore, existing non-precious metal heterogeneous Ni-Sn catalysts exhibit extremely low selectivity for the target products nerol and geraniol, failing to meet industrial production requirements. Bulk Ni-Sn intermetallic compound catalysts suffer from large particle size, poor activity, and demanding reaction conditions.

[0005] Therefore, there is an urgent need to provide a low-cost, highly active, highly selective, and highly stable TiO2-supported Ni-Sn intermetallic compound catalyst to solve the problems of high cost of noble metal catalysts, difficulty in separating non-noble metal homogeneous catalysts, low selectivity of existing Ni-Sn-based catalysts, and harsh reaction conditions of bulk intermetallic compounds in the existing technology, so as to realize the efficient, green, and large-scale preparation of nerol and geraniol from citral. Summary of the Invention

[0006] The purpose of this invention is to provide a Ni-Sn / TiO2 catalyst, its preparation method, and its application to solve the above-mentioned problems.

[0007] This invention provides a Ni-Sn / TiO2 catalyst, comprising a TiO2 support and a Ni-Sn intermetallic compound supported on the TiO2 support. The molar ratio of Sn to Ni in the Ni-Sn intermetallic compound is 0.5:1 to 2:1, preferably 1:1 to 2:1. The Ni-Sn intermetallic compound contains Ni. 2.7 Sn2 phase, Ni3Sn4 phase, and Ni 2.7 A mixed phase of Sn2 and Ni3Sn4 phases.

[0008] Preferably, the catalyst is prepared using TiO2 as a support, and the TiO2 support can be rutile phase, anatase phase, or commercially available TiO2 of type P25. The Ni-Sn intermetallic compound supported on the TiO2 support has a Ni loading of 3 wt.% to 50 wt.%.

[0009] Preferably, the molar ratio of Sn to Ni is 1:1, and the Ni-Sn intermetallic compound is Ni. 2.7 Sn2 phase.

[0010] Preferably, the molar ratio of Sn to Ni is (1:1) to (1:2), and the Ni-Sn intermetallic compound contains Ni. 2.7 A mixed phase of Sn2 and Ni3Sn4 phases.

[0011] Preferably, the molar ratio of Sn to Ni is 1:2, and the Ni-Sn intermetallic compound is the Ni3Sn4 phase.

[0012] A method for preparing the Ni-Sn / TiO2 catalyst as described above is provided, comprising the following steps: (a) Dissolve the tin source in the first solvent to obtain a tin source solution; (b) The TiO2 support is impregnated in the tin source solution of step (a); (c) After impregnation, remove the first solvent and dry to obtain the tin-loaded precursor; (d) Dissolve the nickel source in a second solvent to obtain a nickel source solution; (e) The tin-loaded precursor obtained in step (c) is immersed in the nickel source solution of step (d); (f) After impregnation, remove the second solvent and dry to obtain the catalyst precursor; (g) The catalyst precursor obtained in step (f) is calcined in an oxygen-containing atmosphere; (h) The calcined product is reduced in a reducing atmosphere to obtain a Ni-Sn intermetallic compound catalyst supported on a TiO2 support. Preferably, the first solvent is acetone and the second solvent is water.

[0013] Preferably, the immersion time in steps (b) and (e) is 5-10 hours; and the drying conditions in steps (c) and (f) are drying in an oven at 80-150°C for 2-12 hours.

[0014] Preferably, the reducing atmosphere in step (h) includes H2, and the H2 reduction temperature is 350-650°C. o C.

[0015] This invention provides an application of the Ni-Sn / TiO2 catalyst described above for the selective hydrogenation of citral to prepare geraniol and nerol, achieving high selectivity for the target products. The specific preparation method is as follows: the catalyst is reacted with hydrogen and citral solution in the presence of a solvent at a reaction temperature of 110-170℃ and a reaction pressure of 2-5 MPa to obtain geraniol and nerol; the solvent is isopropanol; the molar ratio of citral solution to Ni in the catalyst is 5-300, and the mass concentration of citral solution is 0.2-30 wt.%.

[0016] Therefore, the present invention, employing the above-mentioned Ni-Sn / TiO2 catalyst, its preparation method, and its application, has the following beneficial effects: (1) By adopting the inexpensive Ni-Sn system, the cost of catalyst is significantly reduced.

[0017] (2) By combining a specific sequential impregnation method with a TiO2 support and an optimized Sn / Ni ratio, a highly dispersed specific Ni-Sn intermetallic compound was prepared under relatively mild conditions, which solved the problem of complex and harsh preparation conditions for intermetallic compounds.

[0018] (4) The catalyst of the present invention exhibits 90%-100% selectivity for unsaturated alcohols in the hydrogenation of citral, which is much higher than that of existing Ni-based catalysts and reaches or even exceeds the level of noble metal catalysts.

[0019] (5) The material structure is easy to adjust. By adjusting the ratio of Ni to Sn, the activity and selectivity of the catalyst can be adjusted. In particular, when the molar ratio of Sn to Ni is between about 1:1 and 1:2, the Ni formed is more efficient. 2.7 The two-phase mixed structure of Sn2 and Ni3Sn4 can serve as active sites for adsorbing hydrogen and adsorbing substrates, respectively, achieving extremely high selectivity for unsaturated alcohols while maintaining high reactivity.

[0020] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0021] Figure 1 The images show the XRD patterns of the intermetallic compound phase structures formed in Examples 1-3 and Comparative Examples 1-3 in the Ni-Sn / TiO2 catalyst, its preparation method, and application of the present invention. Specifically, a is the XRD pattern of the intermetallic compound phase structure in Comparative Example 1, b is the XRD pattern of the intermetallic compound phase structure in Comparative Example 2, c is the XRD pattern of the intermetallic compound phase structure in Comparative Example 3, d is the XRD pattern of the intermetallic compound phase structure in Example 1, e is the XRD pattern of the intermetallic compound phase structure in Example 2, and f is the XRD pattern of the intermetallic compound phase structure in Example 3. Detailed Implementation

[0022] To better understand the above technical solutions, a detailed description of the solutions will be provided below in conjunction with the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0023] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms, and “multiple” generally includes at least two unless the context clearly indicates otherwise.

[0024] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or device that includes said element.

[0025] Example 1 Prepare a Ni-Sn / TiO2 catalyst with a Sn to Ni molar ratio of 1:1; The solution was prepared by sequential impregnation. 1.1533 g of SnCl2·2H2O was weighed and dissolved in 50 mL of acetone. After complete dissolution, 3 g of TiO2 was weighed and added to the solution, with rutile phase selected. The solution was stirred at 35 °C for 8 h. The acetone was removed by rotary evaporator and the solution was dried in an oven at 120 °C for 12 h. The solution was then ground and sieved.

[0026] Dissolve 1.4864 g of Ni(NO3)2·6H2O in 50 mL of deionized water until completely dissolved. Add the sample collected in the previous step, stir at 60°C for 8 hours, remove moisture using a rotary evaporator, dry in a 120°C oven for 12 hours, grind, and sieve. (400...) o Calcination in air at 400°C for 4 hours. o The catalyst was obtained by reduction with CH2 for 3 h. XRD results showed that a pure-phase Ni was formed on the support. 2.7 Sn2 intermetallic compounds, such as Figure 1 As shown in d.

[0027] Example 2 Prepare a Ni-Sn / TiO2 catalyst with a Sn to Ni molar ratio of 3:4; The solution was prepared by sequential impregnation. 1.5377 g of SnCl2·2H2O was weighed and dissolved in 50 mL of acetone. After complete dissolution, 3 g of TiO2 was weighed and added to the solution, with rutile phase selected. The solution was stirred at 35 °C for 8 h. The acetone was removed by rotary evaporator and the solution was dried in an oven at 120 °C for 12 h. The solution was then ground and sieved.

[0028] Dissolve 1.4864 g of Ni(NO3)2·6H2O in 50 mL of deionized water until completely dissolved. Add the sample collected in the previous step, stir at 60°C for 8 hours, remove moisture using a rotary evaporator, dry in a 120°C oven for 12 hours, grind, and sieve. (400...) o Calcination in air at 400°C for 4 hours. o CH2 reduction for 3 h yielded the catalyst. XRD results showed that Ni was formed on the support. 2.7 A mixed phase of Sn2 and Ni3Sn4, such as Figure 1 As shown in e.

[0029] Example 3 Prepare a Ni-Sn / TiO2 catalyst with a Sn to Ni molar ratio of 1:2; The sample was prepared using a sequential impregnation method. 2.3066 g of SnCl₂·2H₂O was dissolved in 50 mL of acetone. After complete dissolution, 3 g of TiO₂ (rutile phase) was added to the solution. The mixture was stirred at 35°C for 8 hours, the acetone was removed using a rotary evaporator, and the sample was dried in a 120°C oven for 12 hours. The solution was then ground and sieved. 1.4864 g of Ni(NO₃)₂·6H₂O was dissolved in 50 mL of deionized water. After complete dissolution, the sample collected in the previous step was added. The mixture was stirred at 60°C for 8 hours, the water was removed using a rotary evaporator, and the sample was dried in a 120°C oven for 12 hours. The solution was then ground and sieved. o Calcination in air at 400°C for 4 hours. o The catalyst was obtained by reduction with CH2 for 3 h. XRD results showed that a pure-phase Ni3Sn4 intermetallic compound was formed on the support, such as... Figure 1 As shown in f in the figure.

[0030] Comparative Example 1 Ni / TiO2 catalyst was prepared by impregnation method. 1.4864 g of Ni(NO3)2·6H2O was dissolved in 50 mL of deionized water until completely dissolved. Then, 3 g of TiO2 (golden red) was added to the solution. The mixture was stirred at 60 °C for 8 hours. Water was removed using a rotary evaporator, and the solution was dried in a 120 °C oven for 12 hours. The catalyst was then ground and sieved. o The catalyst was obtained by calcination in air at C for 4 h and reduction with H2 at 400℃ for 3 h. The crystal phase of the synthesized comparative catalyst was confirmed by XRD, as shown below. Figure 1 As shown in 'a'.

[0031] Comparative Example 2 A Ni-Sn / TiO2 catalyst with a Sn to Ni molar ratio of 3:1 was prepared by sequential impregnation method.

[0032] Weigh 0.3844g SnCl2·2H2O and dissolve it in 50mL acetone. After complete dissolution, weigh 3g TiO2 (golden red) and add it to the solution. Stir at 35℃ for 8 hours. Remove the acetone using a rotary evaporator. Dry in an oven at 120℃ for 12 hours. Grind and sieve.

[0033] Dissolve 1.4864 g of Ni(NO3)2·6H2O in 50 mL of deionized water until completely dissolved. Add the sample collected in the previous step, stir at 60°C for 8 hours, remove moisture using a rotary evaporator, dry in a 120°C oven for 12 hours, grind, and sieve. (400...) o Calcination in air at 400°C for 4 hours. o The catalyst was obtained after reduction with CH2 for 3 h. XRD results showed that a pure-phase Ni3Sn intermetallic compound was formed on the support, such as... Figure 1 As shown in b in the figure.

[0034] Comparative Example 3 A Ni-Sn / TiO2 catalyst with a Sn to Ni molar ratio of 3:2 was prepared by a sequential impregnation method.

[0035] Weigh 0.7687g SnCl2·2H2O and dissolve it in 50mL acetone. After complete dissolution, weigh 3g TiO2 (golden red) and add it to the solution. Stir at 35℃ for 8 hours. Remove the acetone using a rotary evaporator. Dry in an oven at 120℃ for 12 hours. Grind and sieve.

[0036] Dissolve 1.4864 g of Ni(NO3)2·6H2O in 50 mL of deionized water until completely dissolved. Add the sample collected in the previous step, stir at 60 °C for 8 hours, remove water using a rotary evaporator, dry in a 120 °C oven for 12 hours, grind and sieve, and then... o Calcination in air at 400°C for 4 hours. o The catalyst was obtained after reduction with CH2 for 3 h. XRD results showed that a pure-phase Ni3Sn2 intermetallic compound was formed on the support, such as... Figure 1 As shown in c in the figure.

[0037] Test Example 1 Hydrogenation performance tests were conducted using catalysts from Examples 1-3 and Comparative Examples 1-3 to investigate the effect of different metal ratios on the catalytic performance of the catalysts.

[0038] The catalytic performance evaluation conditions are as follows: a batch reactor was used. Due to the different hydrogenation activities of different catalysts for citral, different citral concentrations were used in the experiment to obtain the selectivity differences of the catalyst at high conversion rates (>80%). The catalyst amount was 0.1 g, the reaction pressure was 4 MPa, and the reaction temperature was 140 °C. o C, reaction time 0.2-48 h. The conversion and selectivity results for different catalysts are shown in Table 1.

[0039] Table 1. Conversion and selectivity results for different catalysts

[0040] The results show that the composition ratio of intermetallic compounds plays a decisive role in catalytic selectivity: the catalysts prepared in Examples 2 and 3 of this invention achieved high selectivity of 96.08% and 97.01% for unsaturated alcohols, respectively, under the condition that the conversion rate of citral both exceeded 90%; while Comparative Example 1, although having a conversion rate as high as 99.68%, had an unsaturated alcohol selectivity of only 0.80%, with almost all of it being converted into saturated aldehyde byproducts; the selectivity of Comparative Examples 2 and 3 was also only 13.74% and 34.12%, respectively.

[0041] Test Example 2 The hydrogenation performance of the catalyst in Example 2 was tested to investigate the effect of temperature on the catalyst's catalytic performance.

[0042] The liquid-phase hydrogenation reaction of citral was carried out in a 100 mL stainless steel high-pressure reactor with a polytetrafluoroethylene liner. 100 mg of catalyst, 0.3 mL of citral, and 50.0 mL of isopropanol were added to the reactor. After sealing, the reactor was purged with hydrogen five times, and then heating was initiated. Once the desired temperature was reached, hydrogen was introduced at 4 MPa, and the hydrogen pressure was maintained constant throughout the reaction. Magnetic stirring was started, and timing was initiated simultaneously. The reaction time ranged from 6 to 17 hours. The products were quantitatively evaluated using a gas chromatograph equipped with a capillary column FFAP (30 m × 0.32 mm × 0.25 μm) and an FID detector. The conversion rate of citral and the selectivity of each product were calculated using the internal standard method. The selectivity of unsaturated alcohols (geraniol and nerol) at citral conversions above 90% was tested at 130 °C, 140 °C, 150 °C, and 160 °C, and the results are shown in Table 2.

[0043] Table 2. Selectivity of the catalyst in Example 2 for unsaturated alcohols at different temperatures.

[0044] The results showed that the catalyst maintained a citral conversion rate of over 90% within a temperature range of 130℃ to 160℃. However, the selectivity for unsaturated alcohols exhibited a trend of first increasing and then decreasing: the selectivity was 91.32% at 130℃, and increased to peak values ​​of 95.88% and 96.34% at 140℃ and 150℃, respectively. When the temperature further increased to 160℃, the selectivity decreased to 92.88%. This indicates that the catalyst exhibits optimal catalytic selectivity within the 140-150℃ range and has a relatively wide applicable temperature window.

[0045] Test Example 3 The hydrogenation performance of the catalyst in Example 2 was tested to investigate the effect of pressure on the catalyst's catalytic performance.

[0046] The liquid-phase hydrogenation reaction of citral was carried out in a 100 mL stainless steel high-pressure reactor with a polytetrafluoroethylene liner. 100 mg of catalyst, 0.3 mL of citral, and 50.0 mL of isopropanol were added to the reactor. After sealing, the reactor was purged with hydrogen five times, and then heating was initiated. Once the temperature reached 140 °C, hydrogen was introduced at the corresponding pressure, and the hydrogen pressure was maintained constant throughout the reaction. Magnetic stirring was started, and timing was initiated simultaneously. The reaction time ranged from 6 to 17 hours. The products were quantitatively evaluated using a gas chromatograph equipped with a capillary column FFAP (30 m × 0.32 mm × 0.25 μm) and an FID detector. The conversion rate of citral and the selectivity of each product were calculated using the internal standard method. The selectivity of unsaturated alcohols (geraniol and nerol) was tested at 2 MPa, 3 MPa, 4 MPa, and 5 MPa when the conversion rate was higher than 90%. The results are shown in Table 3.

[0047] Table 3 Selectivity of the catalyst in Example 2 for unsaturated alcohols under different pressures

[0048] The results showed that within a pressure range of 2 MPa to 5 MPa, the catalyst maintained a citral conversion rate of over 90%. The selectivity for unsaturated alcohols also exhibited a pattern of first increasing and then decreasing: at 2 MPa, the selectivity was 91.34%, increasing to maximum values ​​of 95.81% and 96.34% at 3 MPa and 4 MPa, respectively. When the pressure further increased to 5 MPa, the selectivity decreased to 92.83%. This indicates that 4 MPa is the optimal hydrogen partial pressure for this reaction system; excessively high or low pressures are detrimental to the selective hydrogenation of carbonyl groups.

[0049] Test Example 4 The catalyst from Example 2 was used for stability testing. The cycling conditions were: 100 mg Ni-Sn / TiO2 catalyst, 0.3 mL citral and 50.0 mL isopropanol, reaction temperature 140 °C, hydrogen partial pressure 4.0 MPa, and reaction time 15 hours. The results are shown in Table 4.

[0050] Table 4. Stability of the catalyst in Example 2

[0051] The results showed that after six repeated hydrogenation reactions, the citral conversion rate of the catalyst decreased only from 95.34% initially to 93.58%, and the unsaturated alcohol selectivity decreased only from 96.34% to 92.82%. All performance indicators remained at a high level, and no significant deactivation was observed. This fully demonstrates that the TiO2-supported Ni-Sn intermetallic compound catalyst prepared in Example 2 possesses excellent structural stability and reusability, meeting the practical needs of continuous industrial production.

[0052] Therefore, this invention employs the aforementioned Ni-Sn / TiO2 catalyst, its preparation method, and its application. By using an inexpensive Ni-Sn system, the catalyst cost is significantly reduced. Through a specific sequential impregnation method combined with a TiO2 support and an optimized Sn / Ni ratio, highly dispersed specific Ni-Sn intermetallic compounds are prepared under relatively mild conditions, solving the problem of complex and demanding preparation conditions for intermetallic compounds.

[0053] The catalyst exhibits 90%-100% selectivity for unsaturated alcohols in the hydrogenation of citral, far exceeding that of existing Ni-based catalysts and reaching or even surpassing the levels of noble metal catalysts. The material structure is easily tunable; by adjusting the Ni to Sn ratio, the catalyst's activity and selectivity can be modified. In particular, when the Sn to Ni molar ratio is between approximately 1:1 and 1:2, the formed Ni... 2.7 The two-phase mixed structure of Sn2 and Ni3Sn4 can serve as active sites for adsorbing hydrogen and adsorbing substrates, respectively, achieving extremely high selectivity for unsaturated alcohols while maintaining high reactivity.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. An application of a Ni-Sn / TiO2 catalyst, characterized in that, The method for selective hydrogenation of citral to prepare geraniol and nerol is as follows: Geraniol and nerol are prepared by reacting the catalyst with hydrogen and a citral solution in the presence of a solvent at a reaction temperature of 110-170℃ and a reaction pressure of 2-5 MPa; the solvent is isopropanol; the molar ratio of citral solution to Ni in the catalyst is 5-300, and the mass concentration of the citral solution is 0.2-30 wt.%. The catalyst comprises a TiO2 support and a Ni-Sn intermetallic compound supported on the TiO2 support, wherein the molar ratio of Sn to Ni in the Ni-Sn intermetallic compound is 0.5:1 to 3:4; the Ni-Sn intermetallic compound contains a Ni3Sn4 phase or Ni 2.7 A mixed phase of Sn2 and Ni3Sn4 phases.

2. The application of the Ni-Sn / TiO2 catalyst according to claim 1, characterized in that, The Ni-Sn intermetallic compound supported on TiO2 has a Ni loading of 3 wt.% to 50 wt.%.

3. The application of the Ni-Sn / TiO2 catalyst according to claim 1, characterized in that, The preparation method of Ni-Sn / TiO2 catalyst includes the following steps: (a) Dissolve the tin source in the first solvent to obtain a tin source solution; (b) The TiO2 support is impregnated in the tin source solution of step (a); (c) After impregnation, remove the first solvent and dry to obtain the tin-loaded precursor; (d) Dissolve the nickel source in a second solvent to obtain a nickel source solution; (e) The tin-loaded precursor obtained in step (c) is immersed in the nickel source solution of step (d); (f) After impregnation, remove the second solvent and dry to obtain the catalyst precursor; (g) The catalyst precursor obtained in step (f) is calcined in an oxygen-containing atmosphere; (h) The calcined product is reduced in a reducing atmosphere to obtain a Ni-Sn intermetallic compound catalyst supported on a TiO2 support.

4. The application of the Ni-Sn / TiO2 catalyst according to claim 3, characterized in that, The first solvent is acetone, and the second solvent is water.

5. The application of the Ni-Sn / TiO2 catalyst according to claim 3, characterized in that, The impregnation time in steps (b) and (e) is 5-10 hours; the drying conditions in steps (c) and (f) are drying in an oven at 80-150℃ for 2-12 hours.

6. The application of the Ni-Sn / TiO2 catalyst according to claim 3, characterized in that, The reducing atmosphere in step (h) includes H2, and the H2 reduction temperature is 350-650 °C. o C.

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