SILICALITE-1 MOLECULAR SIEVE-BASED CATALYST AND PREPARATION METHOD FOR 1,2-PENTANEDIOL USING SAID CATALYST

Abstract

An organic-base functionalized silicalite-1 molecular sieve-encapsulated metal nanoparticles catalyst and a preparation method therefor, as well as a method for preparing 1,2-pentanediol from biomass-derived furfuryl alcohol by hydrogenolysis using said catalyst. When the catalyst is used in a reaction preparing 1,2-pentanediol from furfuryl alcohol by hydrogenolysis, the catalyst has high hydrogenolysis activity under relatively mild reaction conditions, significantly increasing the conversion rate of furfuryl alcohol and 1,2-pentanediol selectivity in the reaction, while also not generating obvious byproducts furfuryl alcohol polymers; the catalyst has good stability and long life, and may be recovered for reuse after the reaction is complete by means of a simple filtration, greatly reducing reaction costs and separation difficulty.

Claims

1. A catalyst for preparing 1,2-pentanediol by hydrogenolysis of furfuryl alcohol, wherein the catalyst comprises a carrier and an active component, the carrier is a silicalite-1 molecular sieve surface-modified with an organic-base silane coupling agent, the active component is metal nanoparticles encapsulated in the pores of the silicalite-1 molecular sieve.

2. The catalyst according to claim 1, wherein the organic-base silane coupling agent is a compound represented by the following general formula (1): ##STR00002## wherein, Base represents an organic basic group, preferably an amino or a polyamine group, the amino is selected from a primary amino, a secondary amino and a tertiary amino; R.sub.1, R.sub.2 and R.sub.3 represent C.sub.1-C.sub.4 alkyls, which are the same or different from each other; n is 1-10; preferably, the organic-base silane coupling agent is one or more of 3-aminopropyltriethoxysilane, 3-(2-aminoethylamino)propyltrimethoxysilane, diethylenetriaminopropyltrimethoxysilane and 3-(dimethylamino)propyltriethoxysilane.

3. The catalyst according to claim 1, wherein the metal nanoparticle is one or more of Ni, Co, Cu, Ru, Rh, Pd, Ir, Pt and Au, preferably Pt and/or Au.

4. The catalyst according to claim 1, wherein the loading amount of the metal nanoparticle is 0.01-5 wt %, based on the mass of the silicalite-1 molecular sieve without surface-modification in the catalyst.

5. The catalyst according to claim 4, wherein the amount of the organic-base silane coupling agent is 0.01-5 mmol/g, based on the mass of the silicalite-1 molecular sieve without surface-modification in the catalyst.

6. A method for preparing the catalyst according to claim 1, wherein the method comprises the steps of: a) reducing an aqueous solution of soluble metal salt by using a reducing agent in the presence of a colloid stabilizing agent to obtain a colloid of metal nanoparticles; b) adding an alcohol, ammonia water and a tetraalkyl orthosilicate to the colloid of metal nanoparticles obtained in step a), and distilling to remove water and alcohol after hydrolyzation, and then drying to obtain a silica gel loaded with the metal nanoparticles; c) crystallizing the silica gel loaded with the metal nanoparticles obtained in step b) by using hydrothermal method under the effect of a template agent, and calcinating at a high temperature to obtain a silicalite-1 molecular sieve encapsulated with metal nanoparticles; d) modifying the surface of the silicalite-1 molecular sieve encapsulated with metal nanoparticles obtained in step c) by using an organic-base silane coupling agent in a solvent to obtain the catalyst.

7. The method according to claim 6, wherein in step a), the soluble metal salt is one or more of a metal nitrate, a metal acetate and a metal chloride, preferably one or more of nickel nitrate, cobalt acetate, copper nitrate, ruthenium chloride, palladium chloride, chloroiridic acid, chloroplatinic acid, and chloroauric acid, more preferably chloroplatinic acid and/or chloroauric acid; the colloid stabilizing agent is one or more of polyvinylpyrrolidone, polyethylene glycol, polyvinyl alcohol, Tween 20, Tween 80 and Span 20, preferably polyvinylpyrrolidone; the reducing agent is one or more of NaBH.sub.4, formaldehyde and hydrazine hydrate, preferably NaBH.sub.4.

8. The method according to claim 6, wherein in step a), the concentration of the aqueous solution of soluble metal salt is 0.1-2 mmol/L, and the ratio between the usage amounts of the colloid stabilizing agent, the soluble metal salt and the reducing agent is 5-20 g: 1 mmol: 5-15 mmol.

9. The method according to claim 6, wherein in step b), the alcohol is a C.sub.1-C.sub.4 linear alcohol or a C.sub.3-C.sub.4 branched alcohol, preferably ethanol; the tetraalkyl orthosilicate is a orthosilicate of C.sub.1-C.sub.4 linear alcohol or C.sub.3-C.sub.4 branched alcohol, preferably tetraethyl orthosilicate (TEOS); the concentration of solute ammonia in the ammonia water is 1-25 wt %, preferably 20-25 wt %; and the ratio between the usage amounts of the alcohol, the solute ammonia in ammonia water and the tetraalkyl orthosilicate is 20-100 mL: 0.5-2.5 g: 1 g.

10. The method according to claim 6, wherein in step c), the template agent is one or more of tetrapropylammonium hydroxide, tetrapropylammonium bromide and tetrapropylammonium chloride, preferably tetrapropylammonium hydroxide, more preferably tetrapropylammonium hydroxide in a form of 25-40 wt % aqueous solution; the molar ratio of the silica gel loaded with the metal nanoparticles to the template agent is 1:0.1-0.5.

11. The method according to claim 6, wherein in step d), the solvent is one or more of a C.sub.1-C.sub.4 linear alcohol, a C.sub.3-C.sub.4 branched alcohol, benzene and toluene, preferably ethanol and/or toluene; the ratio between the usage amounts of the organic-base silane coupling agent, the silicalite-1 molecular sieve and the solvent is 0.01-5 mmol: 1 g: 20-100 mL, and the reaction conditions are as follows: reacting at 30-100 C. for 4-24 h.

12. A method for preparing 1,2-pentanediol by hydrogenolysis of furfuryl alcohol using the catalyst according to claim 1, wherein, in a batch kettle, an aqueous solution of furfuryl alcohol with a mass percentage concentration of 20-100% is used, the usage amount of the catalyst is 0.1-10 wt %, preferably 0.5-5 wt % based on the mass of the solute furfuryl alcohol; the reaction temperature is 50-200 C., preferably 60-120 C.; the gauge pressure of hydrogen is 0.5-10 MPa, preferably 1-5 MPa; the reaction time is 1-24 hours, preferably 2-6 hours; or wherein in a fixed bed reactor, an aqueous solution of furfuryl alcohol with a mass percentage concentration of 20-100% is used, the mass space velocity of the solute furfuryl alcohol/catalyst is 0.5-4 h.sup.1, preferably 1-3 h.sup.1; the volume space velocity of hydrogen/catalyst is 500-1500 h.sup.1, preferably 800-1200 h.sup.1; the reaction temperature is 50-200 C., preferably 60-120 C.; and the gauge pressure of hydrogen is 0.5-10 MPa, preferably 1-5 MPa.

13. (canceled)

14. The method according to claim 12, wherein the catalyst needs to be in-situ reduced in hydrogen before use, and the reduction conditions are as follow: the gauge pressure of hydrogen is 0.1-1 MPa, preferably 0.2-0.4 MPa; the flow rate of H.sub.2 per 100 g of used catalyst is 0.5-20 L/min, preferably 1-15 L/min; the reduction temperature is 50-250 C., preferably 100-200 C.; the reduction time is 1-10 hours, preferably 2-6 hour.

15. (canceled)

16. The catalyst according to claim 2, wherein the loading amount of the metal nanoparticle is 0.01-5 wt %, based on the mass of the silicalite-1 molecular sieve without surface-modification in the catalyst.

17. The catalyst according to claim 2, wherein the loading amount of the metal nanoparticle is 0.1-2 wt %, the amount of the organic-base silane coupling agent is 0.1-2 mmol/g, based on the mass of the silicalite-1 molecular sieve without surface-modification in the catalyst.

18. The catalyst according to claim 3, wherein the loading amount of the metal nanoparticle is 0.1-2 wt %, the amount of the organic-base silane coupling agent is 0.1-2 mmol/g, based on the mass of the silicalite-1 molecular sieve without surface-modification in the catalyst.

19. The method according to claim 7, wherein in step a), the concentration of the aqueous solution of soluble metal salt is 0.1-2 mmol/L, and the ratio between the usage amounts of the colloid stabilizing agent, the soluble metal salt and the reducing agent is 5-20 g: 1 mmol: 5-15 mmol.

20. The method according to claim 7, wherein in step b), the alcohol is a C.sub.1-C.sub.4 linear alcohol or a C.sub.3-C.sub.4 branched alcohol, preferably ethanol; the tetraalkyl orthosilicate is a orthosilicate of C.sub.1-C.sub.4 linear alcohol or C.sub.3-C.sub.4 branched alcohol, preferably tetraethyl orthosilicate (TEOS); the concentration of solute ammonia in the ammonia water is 1-25 wt %, preferably 20-25 wt %; and the ratio between the usage amounts of the alcohol, the solute ammonia in ammonia water and the tetraalkyl orthosilicate is 20-100 mL: 0.5-2.5 g: 1 g.

21. The method according to claim 7, wherein in step c), the template agent is one or more of tetrapropylammonium hydroxide, tetrapropylammonium bromide and tetrapropylammonium chloride, preferably tetrapropylammonium hydroxide, more preferably tetrapropylammonium hydroxide in a form of 25-40 wt % aqueous solution; the molar ratio of the silica gel loaded with the metal nanoparticles to the template agent is 1:0.1-0.5.

22. The method according to claim 7, wherein in step d), the solvent is one or more of a C.sub.1-C.sub.4 linear alcohol, a C.sub.3-C.sub.4 branched alcohol, benzene and toluene, preferably ethanol and/or toluene; the ratio between the usage amounts of the organic-base silane coupling agent, the silicalite-1 molecular sieve and the solvent is 0.01-5 mmol: 1 g: 20-100 mL, and the reaction conditions are as follows: reacting at 30-100 C. for 4-24 h.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0046] FIG. 1 is a schematic view showing the flow of the above-mentioned preparation method and the structures of intermediate products and final products of the catalyst.

[0047] FIG. 2 is a TEM photograph of the Catalyst 1# prepared in Example 1 of the present invention.

[0048] FIG. 3 is a TEM photograph of the Catalyst 1-1# prepared in Comparative Example 1.

[0049] FIG. 4 is a FTIR spectrum of the Catalyst 1# prepared in Example 1 of the present invention.

DESCRIPTION OF THE REFERENCE SIGNS

In FIG. 1,

[0050] 1. The colloid of metal nanoparticles;
2. The silica gel loaded with metal nanoparticles;
3. The silicalite-1 molecular sieve encapsulated with metal nanoparticles;
4. The catalyst of the present invention.

EMBODIMENTS

[0051] The present invention will be further described in conjunction with embodiments, and it should be noted that the embodiments are not intended to limit the scope of the present invention.

[0052] The reagents in the present invention were mainly purchased from Sinopharm Chemical Reagent Co., Ltd., and the organic-base silane coupling agent was purchased from Sigma-Aldrich.

[0053] In the following examples and comparative examples, % used is molar percentage unless otherwise specified.

[0054] Transmission electron microscopy (TEM) was performed on an instrument of JEM-2100F (JEOL, Japan) using an accelerating voltage of 200 kV.

[0055] Infrared spectroscopy (FTIR) was performed on a Bruker Equinox 55 Fourier infrared spectrometer using a KBr pellet with a scan wavelength range of 4000-400 cm.sup.1.

[0056] The structure of the pores was determined by N.sub.2 isothermal adsorption and desorption (77K) using an instrument of Quantachrome Autosorb-1-CTCD-MS. The catalyst samples were degassed at 250 C. for 12 h before testing. The specific surface area (S.sub.BET) was calculated from the relative pressure (P/P.sub.0) data of 0.05-0.20. The pore volume (V.sub.p) was the adsorption amount at the maximum relative pressure (P/P.sub.0 0.99). The pore diameter was calculated from the adsorption branch data through Barrett-Joyner-Halenda formula.

[0057] The test instrument used for estimating the performance of the catalyst is a Shimadzu GC-2010 gas chromatograph (hydrogen flame detector, with nitrogen as a carrier gas), which is equipped with a DB-5 capillary column (the fixed solution thereof is 5% of phenyl methyl siloxane, 30 m0.32 mm0.25 m) and a hydrogen flame detector (FID). The temperature of the sample injector and detector were both 280 C.; the column temperature was programmed as follows: the column temperature was initially maintained at 100 C. for 0.5 minutes, and the temperature was raised to 260 C. at 15 C./min and maintained for 5 minutes. The column pressure was 8.5868 psi (approximately 59.2 kPa), the flow rate was 1.5 mL/min. Sample injection amount: 0.2 L. The conversion rate and the selectivity were calculated using the area normalization method.

Examples 1-9

[0058] 1. Catalyst Preparation

[0059] In Examples 1-9, Catalysts 1#-9# were prepared by using different soluble metal salts and organic-base silane coupling agents respectively, according to the following steps.

[0060] a) polyvinylpyrrolidone (PVP) was added to an aqueous solution containing a soluble metal salt (with a concentration of 1 mmol/L) and stirred at 0 C. for 30 min, and an aqueous solution of NaBH.sub.4 (0.1 mol/L) was added rapidly, wherein the ratio between the usage amounts of PVP, the soluble metal salt and the aqueous solution of NaBH.sub.4 was 11.2 g: 1 mmol: 100 mL, and stirred for 2 hours to obtain a colloid of metal nanoparticles;

[0061] b) under stirring, ethanol and 25 wt % of concentrated ammonia water were added to the above colloid of metal nanoparticles, and 346.67 g of tetraethyl orthosilicate (TEOS) was added, the ratio between the usage amounts of the ethanol, the concentrated ammonia water and TEOS was 50 mL: 5 mL: 1 g; after 8 h, the water and the ethanol were distilled off, and the residue was dried at 100 C. overnight to obtain a silica gel loaded with metal nanoparticles;

[0062] c) the silica gel loaded with metal nanoparticles obtained in step b) was uniformly mixed with a 40 wt % aqueous solution of TPAOH, and then transferred to a hydrothermal kettle, wherein the molar ratio of the silica gel loaded with metal nanoparticles to TPAOH was 1:0.3; the mixture obtained was treated at 180 C. for 3 days, filtered, dried at 100 C. overnight, and calcined at 550 C. for 4 h to obtain a silicalite-1 molecular sieve encapsulated with metal nanoparticles;

[0063] d) an organic-base silane coupling agent and the silicalite-1 molecular sieve encapsulated with metal nanoparticles obtained in step c) were added to ethanol, wherein the ratio between the amounts of the ethanol and the silicalite-1 molecular sieve encapsulated with metal nanoparticles was 50 ml: 1 g; and then the mixture obtained was reacted at 80 C. for 8 h, filtered, and dried at 100 C. overnight to obtain the Catalysts 1#-9# of the present invention.

[0064] Table 1 shows the types and contents of metal nanoparticles encapsulated by per 100 g of the silicalite-1 molecular sieve without surface-modification (i.e., pure SiO.sub.2) in the catalysts prepared in Examples 1-9, the usage amounts of soluble metal salts in the step a) of Examples 1-9, and the types and usage amounts of the organic-base silane coupling agents used in step d), wherein the soluble metal salt used in each of the examples was the above-mentioned soluble metal salt corresponding to the metal shown in Table 1. The content of the encapsulated metal nanoparticles can be calculated according to the following formula: (m.sub.cm.sub.SiO2)/m.sub.SiO2100%; wherein m.sub.c is the mass of the silicalite-1 molecular sieve encapsulated with metal nanoparticles obtained in step c), and m.sub.SiO2 is the converted mass of pure SiO.sub.2, which is calculated from the amount of alkyl orthosilicate used in step b).

TABLE-US-00001 TABLE 1 Preparation conditions for Catalyst 1#-9# Usage Usage amount Content amount of of of soluble organic- metal metal salt Organic-base silane base Catalyst Metal wt % mmol coupling agent mmol 1# Ni 4 68.14 3-aminopropyltriethoxysilane 50 2# Co 4.5 76.40 3-(2-aminoethylamino)propyltrimethoxysilane 100 3# Cu 5 78.74 diethylenetriaminopropyltrimethoxysilane 150 4# Ru 0.8 7.92 3-(dimethylamino)propyltriethoxysilane 200 5# Rh 1.2 11.66 diethylenetriaminopropyltrimethoxysilane 250 6# Pd 1.0 9.40 3-(dimethylamino)propyltriethoxysilane 300 7# Ir 1.8 9.37 3-aminopropyltriethoxysilane 350 8# Pt 0.4 2.05 3-(2-aminoethylamino)propyltrimethoxysilane 400 9# Au 1.6 8.12 3-(dimethylamino)propyltriethoxysilane 450

[0065] FIG. 2 is a transmission electron microscopy (TEM) photograph of Catalyst 1# prepared in Example 1, and it can be seen that the metal nanoparticles (black dots in the photograph) are all at the inside of the silicalite-1 molecular sieve instead of the edge thereof, indicating that the metal nanoparticles are well encapsulated in the molecular sieve.

[0066] As shown in FIG. 4, in the apparent absorption peaks of the infrared spectrum (FTIR) diagram of Catalyst 1#, the wavelengths of 3500, and 3400 cm.sup.1 are the characteristic absorptions of NH.sub.2, and the wavelengths of 2925, 2825 and 1470 cm.sup.1 are the characteristic absorptions of CH2-, indicating that the organic-base has been grafted onto the silicalite-1 molecular sieve encapsulated with metal nanoparticles.

[0067] The silicalite-1 molecular sieve encapsulated with the nanoparticles of metal Ni and Catalyst 1# were characterized by N.sub.2 isothermal adsorption and desorption. The specific surface area, pore volume and pore diameter of the two were shown in Table 2 below.

TABLE-US-00002 TABLE 2 Characterization results of N.sub.2 isothermal adsorption and desorption Specific Pore Pore surface area volume diameter Sample m.sup.2/g cm.sup.3/g nm Silicalite-1 molecular sieve 838 0.439 0.55 encapsulated with the nanoparticles of metal Ni Catalyst 1# 837 0.438 0.55

[0068] It can be seen from the above results that there was no significant change on the pore structure of the silicalite-1 molecular sieve after grafted with organic-base, indicating that the organic-base was grafted on the outer surface of the silicalite-1 molecular sieve.

[0069] 2. Evaluation of Catalyst Performance

[0070] 2.1 Batch Kettle

[0071] Evaluations of the catalysts of the present invention were carried out in a batch kettle having a volume of 3000 mL and a material of stainless steel. A certain amount of catalyst was added to the batch kettle, and reduced in situ to activate the same. The mass percentages of the amount of added catalysts relative to the amount of furfuryl alcohol for hydrogenolysis (calculated as solute) are shown in Table 3. The reduction temperature was 200 C., the pressure of H.sub.2 was 0.3 MPa, the flow rate of H.sub.2 was 1.5 L/min, and the reduction was carried out for 4 hours.

[0072] After the above reduction, the temperature of the reaction kettle was lowered to the reaction temperature for hydrogenolysis of furfuryl alcohol, 2000 g of aqueous solution of furfuryl alcohol with a certain concentration was added, the temperature was again adjusted to the reaction temperature for hydrogenolysis, and hydrogen with a certain pressure was charged to start the reaction. After a certain period of reaction, the temperature was lowered and the pressure was released. A liquid sample was taken and analyzed by the above gas chromatography equipped with DB-5 capillary column and flame ion (FID) detector. The specific reaction conditions and the evaluation of catalyst performance are shown in Table 3.

[0073] The catalysts of the present invention were reused in the batch reaction kettle by the following method: after the reaction in the previous kettle was completed, the reaction liquid was removed through a filter placed inside the reactor, the catalyst was left in the reaction kettle; 2000 g of aqueous solution of furfuryl alcohol with a certain concentration was added again, the temperature was adjusted to the reaction temperature, and hydrogen with a certain pressure was charged to start the reaction, which ended after a certain period of time, the specific conditions were the same as those in the previous reaction.

TABLE-US-00003 TABLE 3 Reaction conditions and evaluation results of catalyst performance using catalysts 1#-9# of the present invention in the batch reaction kettle Reaction conditions Concentration Used for the first time Reused for 20 times of furfuryl Catalyst/furfuryl Reaction Hydrogen Reaction Conversion Conversion alcohol alcohol temperature pressure time rate Selectivity rate Selectivity Catalyst wt % wt % C. MPa h % % % % 1# 50 9 100 3.5 2.5 99.2 65.0 99.5 65.3 2# 60 7 95 4 3 99.7 64.3 99.6 64.2 3# 40 8 100 5 4 99.5 71.8 99.7 71.9 4# 90 4 105 3 3.5 99.3 76.0 99.2 76.4 5# 70 3 120 2 4 99.4 67.3 99.5 67.1 6# 80 2 90 1.5 5.6 99.3 76.9 99.3 76.8 7# 30 5 110 2.5 4.8 99.2 77.5 99.2 77.4 8# 20 2.5 85 1 3.2 99.7 83.4 99.8 83.5 9# 100 1 115 4.5 6 99.9 80.2 99.5 80.1

[0074] As can be seen from Table 3, catalysts 1#-9# prepared in Examples 1-9 of the present invention showed good activity and 1,2-pentanediol selectivity for the hydrogenolysis of furfuryl alcohol. High conversion rates were obtained at relatively low reaction temperatures. In particular, the catalysts of the present invention have excellent stabilities, and the activities thereof can be substantially maintained after 20 times of reuse.

[0075] 2.2 Fixed Bed

[0076] Evaluation of the catalyst of the present invention were carried out in a fixed bed reactor, which is a stainless steel tube having an outer diameter of 40 mm, an inner diameter of 20 mm and a length of 1000 mm. 50 g of the catalyst was charged into the reactor, and the catalyst was reduced in situ before the reaction, the reduction temperature was 200 C., the pressure of H.sub.2 was 0.3 MPa, the flow rate of H.sub.2 was 1.5 L/min, and the reduction was carried out for 4 hours. After the reduction ended, the temperature was lowered to the reaction temperature, the hydrogen/catalyst volume space velocity was set to 1000 h.sup.1, the flow rate of the aqueous solution of furfuryl alcohol was adjusted to obtain the desired furfuryl alcohol (calculated as solute)/catalyst mass space velocity, and the pressure was adjusted to the required reaction pressure. The specific reaction conditions are shown in Table 4. A liquid sample was taken online and analyzed by the gas chromatography with DB-5 capillary column and flame ion (FID) detector as described above.

TABLE-US-00004 TABLE 4 Reaction conditions and evaluation results of catalyst performance of the reaction using catalysts 1#-9# of the present invention in the fixed bed reactor Reaction conditions Concentration Furfuryl alcohol/ After running for 10 h After running for 500 h of furfuryl Hydrogen catalyst Conversion Conversion alcohol Temperature pressure mass space velocity rate Selectivity rate Selectivity Catalyst wt % C. MPa h.sup.1 % % % % 1# 50 100 5.5 2.5 99.2 65.0 99.3 64.9 2# 60 95 6 3 99.7 64.3 99.6 64.5 3# 40 100 4.5 2 99.5 71.8 99.5 72.0 4# 90 105 8 1.5 99.3 76.0 99.4 75.8 5# 70 120 7 1 99.4 67.3 99.2 67.7 6# 80 90 9 1.6 99.3 76.9 99.5 77.0 7# 30 110 10 1.8 99.2 77.5 99.3 77.8 8# 20 85 7.5 2 99.7 83.4 99.8 83.5 9# 100 115 8.5 2.2 99.9 80.2 99.8 80.1

[0077] As can be seen from Table 4, in the fixed bed reactor, catalysts 1#-9# showed good activity and 1,2-pentanediol selectivity for the hydrogenolysis of furfuryl alcohol, and the life test of 500 h showed that the catalysts of the present invention had excellent stabilities.

Comparative Examples 1-9

[0078] As to Comparative Examples 1-9, the catalysts in which the metal nanoparticles were loaded on the outer surface of the organic-base-functionalized silicalite-1 molecular sieve were prepared as Comparative Catalysts 1-1#-1-9#, respectively.

[0079] a) ethanol and 25 wt % of concentrated ammonia water were mixed under stirring, 346.67 g of tetraethyl orthosilicate (TEOS) was added, and the ratio between the usage amounts of ethanol, concentrated ammonia and TEOS was 50 mL: 5 mL: 1 g; after 8 h, the water and ethanol was distilled off, and the residue was dried at 100 C. overnight to obtain 100 g of silica gel;

[0080] b) the silica gel obtained in step a) was uniformly mixed with 40 wt % of aqueous solution of TPAOH and transferred to a hydrothermal kettle, wherein the molar ratio of silica gel to TPAOH was 1:0.3; and then the silica gel was treated at 180 C. for 3 days, filtered, dried at 100 C. overnight, and calcinated at 550 C. for 4 h to obtain a silicalite-1 molecular sieve;

[0081] c) an organic-base silane coupling agent and the silicalite-1 molecular sieve obtained in the step b) were added to ethanol, wherein the ratio of the amount of ethanol to the silicalite-1 molecular sieve was 50 ml: 1 g; the organic-base silane coupling agent and the silicalite-1 molecular sieve were reacted at 80 C. for 8 h, filtered, and dried at 100 C. overnight to obtain an organic-base functionalized silicalite-1 molecular sieve;

[0082] d) polyvinylpyrrolidone (PVP) was added to an aqueous solution containing a soluble metal salt (with a concentration of 1 mmol/L), and stirred at 0 C. for 30 min, and then an aqueous solution of NaBH.sub.4 (0.1 mol/L) was rapidly added, wherein the ratio between the usage amounts of PVP, the soluble metal salt and the aqueous solution of NaBH.sub.4 was 11.2 g: 1 mmol: 100 mL, and stirred for 2 h to obtain a colloid of metal nanoparticles;

[0083] e) the organic-base functionalized silicalite-1 molecular sieve obtained in the step c) was added to the colloid of metal nanoparticles obtained in the step d), stirred for 8 hours, filtered, and dried at 100 C. overnight to obtain Comparative Catalysts 1-1#-1-9#.

[0084] Table 5 shows the types and contents of metal nanoparticles loaded on per 100 g of the silicalite-1 molecular sieve without surface-modification (i.e., pure SiO.sub.2) in the catalysts prepared in Comparative Examples 1-9, the usage amounts of soluble metal salts in step a) of Comparative Examples 1-9, and the types and amounts of the organic-base silane coupling agents used in the step c), wherein the soluble metal salt used in each of the Comparative Examples was the above-mentioned soluble metal salt corresponding to the metal shown in Table 5.

TABLE-US-00005 TABLE 5 Preparation conditions for Comparative Catalysts 1-1#-1-9# Usage Content amount of Usage of soluble amount of metal metal salt organic-base Catalyst Metal wt % mmol Organic-base silane coupling agent mmol 1-1# Ni 4 68.14 3-aminopropyltriethoxysilane 50 1-2# Co 4.5 76.40 3-(2-aminoethylamino)propyltrimethoxysilane 100 1-3# Cu 5 78.74 diethylenetriaminopropyltrimethoxysilane 150 1-4# Ru 0.8 7.92 3-(dimethylamino)propyltriethoxysilane 200 1-5# Rh 1.2 11.66 diethylenetriaminopropyltrimethoxysilane 250 1-6# Pd 1.0 9.40 3-(dimethylamino)propyltriethoxysilane 300 1-7# Ir 1.8 9.37 3-aminopropyltriethoxysilane 350 1-8# Pt 0.4 2.05 3-(2-aminoethylamino)propyltrimethoxysilane 400 1-9# Au 1.6 8.12 3-(dimethylamino)propyltriethoxysilane 450

[0085] FIG. 3 is a transmission electron microscopy (TEM) photograph of the Catalyst 1-1#. It can be seen that the metal nanoparticles (black dots in the graph) are at the edge of the silicalite-1 molecular sieve, indicating that the metal nanoparticles are on the outer surface of the molecular sieve.

[0086] After activated, Comparative Catalysts 1-1#-1-9# were used for the reaction of hydrogenolysis of furfuryl alcohol to prepare 1,2-pentanediol, and the performance evaluation and reuse were carried out in the same manner as in Examples 1-9. The results of the performance evaluation are shown in Table 6 below.

TABLE-US-00006 TABLE 6 Performance evaluation results of Comparative Catalysts 1-1#-1-9# Reaction conditions Concentration Used for the first time Reused for 5 times of furfuryl Catalyst/furfuryl Reaction Hydrogen Reaction Conversion Conversion alcohol alcohol temperature pressure time rate Selectivity rate Selectivity Catalyst wt % wt % C. MPa h % % % % 1-1# 50 9 100 3.5 2.5 92.7 15.0 59.3 15.1 1-2# 60 7 95 4 3 89.3 14.3 44.0 14.2 1-3# 40 8 100 2.5 4 83.5 21.8 38.6 21.4 1-4# 90 4 105 3 3.5 94.1 26.0 62.4 25.8 1-5# 70 3 120 2 4 85.9 17.3 57.2 17.4 1-6# 80 2 90 1.5 5.6 76.4 16.9 37.1 16.8 1-7# 30 5 110 2 4.8 75.6 19.5 40.5 19.9 1-8# 20 2.5 85 3.5 3.2 83.8 33.4 46.7 32.7 1-9# 100 1 115 4.5 6 89.0 20.2 58.4 19.9

[0087] As can be seen from Table 6, since the metal nanoparticles are on the outer surface of the organic-base functionalized silicalite-1 molecular sieve, the furfuryl alcohol molecules and the metal nanoparticles are both in an alkaline environment, the shape selectivity of the pores of the silicalite-1 molecular sieve cannot be utilized, therefore, the activity and the 1,2-pentanediol selectivity of Catalysts 1-1#-1-9# for the hydrogenolysis of furfuryl alcohol are significantly lower than that of Catalysts 1#-9#; in addition, although the polymerization of furfuryl alcohol was obviously reduced during the reaction, but due to lack of the encapsulation protection of the silical-1 molecular sieve, it is inevitable that some of the active sites of the metal nanoparticles are covered, the stability is not good, and the activity decreased significantly only after 5 times of reuse.

Comparative Examples 10-18

[0088] As to Comparative Examples 10-18, the same preparation methods as in Examples 1-9 were carried out without implementing step d), and the catalysts in which metal nanoparticles were encapsulated in a silicalite-1 molecular sieve without organic-base functionalization were prepared as Comparative Catalysts 2-1#-2-9#.

[0089] The Comparative Catalysts 2-1#-2-9# were activated in the batch kettle, and the activation conditions were the same as those in Examples 1-9. Subsequently, the reaction for preparing 1,2-pentanediol by hydrogenolysis of furfuryl alcohol was carried out using Comparative Catalysts 2-1#-2-9#, and the performance evaluations of Comparative Catalysts 2-1#-2-9# were carried out in the same manner as in Examples 1-9. The results are shown in Table 7 below.

TABLE-US-00007 TABLE 7 Performance evaluation results of Comparative Catalyst 2-1#-2-9# Reaction conditions Concentration Used for the first time Reused for 5 times of furfuryl Catalyst/furfuryl Reaction Hydrogen Reaction Conversion Conversion alcohol alcohol temperature pressure time rate Selectivity rate Selectivity Catalyst wt % wt % C. MPa h % % % % 2-1# 50 9 100 3.5 2.5 92.2 13.0 81.2 12.2 2-2# 60 7 95 4 3 90.7 22.1 80.7 20.0 2-3# 40 8 100 2.5 4 91.5 20.6 75.5 17.1 2-4# 90 4 105 3 3.5 92.3 23.4 84.3 18.7 2-5# 70 3 120 2 4 98.4 18.5 72.4 14.6 2-6# 80 2 90 1.5 5.6 93.3 20.9 85.3 16.3 2-7# 30 5 110 2 4.8 95.2 23.2 81.2 19.9 2-8# 20 2.5 85 3.5 3.2 91.7 31.7 76.7 25.4 2-9# 100 1 115 4.5 6 98.9 21.5 82.9 17.8

[0090] As can be seen from Table 7, since no organic-base is present on the outer surface of the silicalite-1 molecular sieve, the furfuryl alcohol molecules undergo obvious polymerization after being heated, and thus the conversion rate is at a higher level. However, although the metal nanoparticles are encapsulated in the silicalite-1 molecular sieve, the amount of furfuryl alcohol which can reach the metal nanoparticles is reduced due to the side reaction of polymerization, and finally the selectivity of 1,2-pentanediol is low. Furthermore, the polymerization of more furfuryl alcohol also brings the problem of poor catalyst stability, and the activity of the catalyst decreases to some extend after 5 times of reuse.

[0091] As can be seen, in order to ensure high activity, high 1,2-pentanediol selectivity and good stability of the catalyst, both the encapsulation of the metal nanoparticles in the molecular sieve and the functionalization of the organic-base on the outer surface are indispensable.

[0092] The contents described above are only preferred embodiments of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that may be readily conceived by those skilled in the art are intended to be included within the scope of the present invention.