Catalyst for preparing furan by gas-phase decarbonylation of furfural as well as preparation and application of catalyst

Abstract

The invention discloses a catalyst for preparing furan through furfural gas-phase decarbonylation reaction as well as a preparation method and application of the catalyst. The active component of the catalyst is prepared by a colloid method and is loaded on the carrier, the main active component of the prepared catalyst is small in metal particle diameter, narrow in distribution and good in dispersity, and the average particle size of the main active component is intensively distributed between 2 nm and 4 nm. The preparation method of the catalyst is simple, the operation condition is mild, and the catalyst is easy to produce; when the catalyst disclosed by the invention is applied to a reaction for preparing furan by decarbonylation of furfural, relatively high furfural conversion rate and relatively high furan selectivity and stability are achieved.

Description

Technical Field

[0001] The present invention relates to a catalyst for the gas-phase decarbonylation reaction of furfural to produce furan, a preparation method thereof, and an application thereof, belonging to the technical field of fine chemical industry. Background Art

[0002] Furan is an important chemical raw material, widely used in organic synthesis and pharmaceutical production, and is used to produce pyrrole, thiophene, tetrahydrofuran, etc. Its market demand is increasing year by year. The traditional methods for preparing furan include decarboxylation of furoic acid, oxidation of furfural, and petroleum method (oxidation of butadiene). Among them, the first two methods have been eliminated due to reasons such as backward technology, poor catalyst activity, and serious pollution, while the petroleum method has an unoptimistic market prospect due to the decreasing annual oil reserves and increasing prices. The raw material of the furfural decarbonylation method is furfural from agricultural and sideline products, and it has the advantages of good catalyst activity and other advantages, meeting the conditions for industrialization.

[0003] The process for the hydrogenation decarbonylation of furfural to produce furan is divided into liquid-phase and gas-phase decarbonylation methods. The operation temperature of the liquid-phase decarbonylation method is relatively mild, but the disadvantages are that the content of precious metal Pd in the catalyst is too high, and the catalyst is prone to coking and deactivation. Patent CN102000569A discloses a Pd / γ-Al 2 O 3 -MO catalyst (MO is an oxide of K, Cs, Li), the Pd loading reaches 5wt%, reacting at a pressure of 0 - 0.5MPa and a temperature of 200 - 259 °C, the furfural conversion rate is 92% - 98%, the furan selectivity is 85 - 94%, and the catalyst life is 100 - 120h. In contrast, although the reaction temperature of the furfural gas-phase decarbonylation process is relatively high (260 - 360 °C), it has obvious advantages in terms of the precious metal loading of the catalyst, furfural conversion rate, furan selectivity, and service life.

[0004] Patent US4780522 discloses a catalyst Pt / γ-Al 2 O 3 -CsCO 3 for the gas-phase decarbonylation of furfural to produce furan, the Pd loading reaches 0.75wt%, at normal pressure, 300 - 360 °C, with a furfural volume space velocity of 1.1h -1 and a molar ratio of furfural to hydrogen of 1.8 / 1.4, the furfural conversion rate is 70% - 99%, the average furan yield is 95%, the catalyst runs for 1430h, and 175 kg of furan is produced per kilogram of precious metal Pt.

[0005] Patent CN1308986A discloses a high-efficiency precious metal catalyst for the gas-phase decarbonylation of furfural to produce furan, using Al 2 O 3 -TiO 2The catalyst is prepared by impregnation method using composite oxide as carrier, the loading amount of active component Pt is 0.4-0.7wt%, and it also contains 0.5-2.0wt% K 2 O or Cs 2 O or MgO or CaO or BaO. The catalyst is at normal pressure, 280 ° C, and the volume space velocity of furfural is 0.9h -1 When the molar ratio of furfural to hydrogen is 0.5-2.0, the conversion rate can reach 80-97% and the selectivity can reach 85-92%.

[0006] Patent CN113398911B discloses CeO 2 -ZrO 2 -Al 2 O 3 The catalyst with composite oxide as carrier, active component Pd loading amount 0.25wt%, auxiliary agent K loading amount 1.0wt%, catalyzes furfural decarbonylation to furan reaction, normal pressure, reaction temperature 260℃, furfural feed volume space velocity 0.8h -1 When the molar ratio of hydrogen to furfural is 1.0, the catalyst life of one pass reaches 500, the furfural conversion rate drops from the initial 99.5% to 93.3%, and the furan selectivity drops from the initial 98.7% to 95.7%. Compared with the existing work, the catalyst has the advantages of low precious metal loading, high activity, good selectivity, and long catalyst life. Each kilogram of precious metal Pd produces 165kg of furan, but the complex carrier preparation process invisibly increases the preparation cost of the catalyst. Summary of the invention

[0007] In order to solve the problems of the prior art, the present invention prepares an active component impregnation liquid by a colloid method and loads it onto a carrier. The prepared catalyst has a small particle size, a narrow distribution, and a good dispersion of the main active component, and its average particle size is less than 3nm. The preparation method of the catalyst of the present invention is simple, the operating conditions are mild, and it is easy to produce; when the catalyst of the present invention is applied to the reaction of furfural decarbonylation to furan, it has a high furfural conversion rate, high furan selectivity and stability.

[0008] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0009] A catalyst for the gas-phase decarbonylation reaction of furfural to furan, its preparation method and application. The catalyst further includes a carrier and active components and promoter components supported on the carrier. The carrier is at least one of alumina, silica, titanium oxide, zinc oxide, and cerium oxide. The active component is at least one of noble metals Pd, Pt, and Ru, and the mass is 0.15-0.3% (preferably 0.18-0.25%) of the mass of the carrier. The promoter component exists in the form of oxides or salts of potassium and sodium, and the loading amount of potassium and sodium (calculated based on the mass of the corresponding salts input) is 1.0-20% (preferably 5.0-10%) of the mass of the carrier.

[0010] The active component of the catalyst is prepared by the colloid method and impregnated on the carrier. The specific preparation steps of the catalyst are as follows: (1). First, take a certain amount of noble metal salt and configure it into a 1000-milliliter aqueous solution, and the noble metal concentration is 0.1-10.0 mmol / L (preferably 1.0-5.0 mmol / L); (2). Then transfer the noble metal solution (1.0-20.0 milliliters) and dilute it with water to 40 milliliters, add polyvinylpyrrolidone (the molar ratio of PVP to noble metal is 5:1-50:1), and then add 10 mL of ethylene glycol dissolved in the aqueous solution, and stir vigorously for a period of time to obtain an active metal impregnation solution; (3). Then add activated alumina (0.1-10 g, preferably 0.5-5.0 g) to the active metal impregnation solution, shake it at 25-100 °C for 5 hours, and then cool it to room temperature; filter and wash the obtained solid, dry it under vacuum at 25-60 °C overnight, and dry it in air at 80-150 °C for 8-48 hours; (4). Take a certain amount of potassium salt and sodium salt and dissolve them in 0.1-12 grams of water, impregnate the catalyst precursor loaded with the active component platinum dried in step (3) for 0.5-12 hours, dry it at 80-150 °C for 8-48 hours, and calcine it at 400 °C for 1-12 hours to obtain the catalyst.

[0011] The noble metal palladium salt is at least one of palladium chloride, palladium nitrate, palladium acetate, chloropalladic acid, sodium chloropalladate, and ammonium chloropalladate; the noble metal platinum salt is at least one of chloroplatinic acid, platinum tetrachloride, platinum nitrate, and platinum acetylacetonate; the salt solution of potassium or sodium is at least one of carbonate, acetate, sulfate, nitrate, and chloride.

[0012] The molecular weight of the polyvinylpyrrolidone is 3000-700000.

[0013] The reaction conditions for the decarbonylation of furfural to furan are: normal pressure, the reaction temperature is 250-360 °C (preferably 280-320 °C), and the mass space velocity of the furfural feed is 0.5-5.0 h -1 (preferably 1.2-3.5 h -1) The molar ratio of hydrogen to furfural is 0.6 - 7.5:1 (preferably 1.5 - 4.5:1).

[0014] The decarbonylation reaction of furfural is carried out according to the following steps: After being heated in a vaporizer, furfural enters the catalyst bed of a fixed-bed reactor together with hydrogen. The decarbonylation reaction of furfural occurs on the catalyst to generate furan. The liquid raw material and the product are collected as reaction liquid after being cooled by low temperature condensation, and the gas product is quantitatively analyzed by on-line chromatography.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0016] (1) The main active component metal particles of the catalyst prepared by the present invention have a small particle size, a narrow distribution, and good dispersion, and their average particle size is concentrated in the range of 2 - 4 nm;

[0017] (2) The catalyst of the present invention with a relatively low noble metal Pd and Pt loading of 0.15 - 0.25% has a furfural conversion rate still close to 100% and a furan selectivity exceeding 99% under the condition of a mass space velocity of 2.32 h -1 (volume space velocity 1.48 h -1 );

[0018] (3) The preparation method of the catalyst of the present invention is simple, the operating conditions are mild, and it is easy to produce. Specific embodiments

[0019] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention. The scope of protection required by the present invention is defined by the appended claims and their equivalents.

[0020] There are no special restrictions on the purity of all raw materials of the present invention, and the reagents used in the following examples are all commercially available. Qualitative analysis of reaction raw materials and liquid products: Agilent gas chromatography-mass spectrometry technology was used to qualitatively analyze furfural, furan, 2-methylfuran, tetrahydrofuran, 2-methyltetrahydrofuran, furfuryl alcohol, and tetrahydrofurfuryl alcohol, and it was confirmed by searching the mass spectrometry library and comparing the retention times of standard substances. Quantitative analysis of reaction liquid products: An Agilent gas chromatograph (the chromatographic column is an HP-5 capillary column, with an FID hydrogen flame detector) was used to quantitatively analyze the products by the internal standard method, and the internal standard was n-heptanol. Drawing of the internal standard working curve: Accurately weigh a total of 4.0 g of standard substances of furfural, furan, 2-methylfuran, tetrahydrofuran, 2-methyltetrahydrofuran, furfuryl alcohol, and tetrahydrofurfuryl alcohol to prepare a standard stock solution, and then separately transfer 0.02 g, 0.05 g, 0.15 g, 0.25 g, 0.45, 0.65, 0.85, and 1.0 g from the stock solution, and then dissolve 0.05 g of n-heptanol, add 1.5 mL of ethanol to make up the volume, and then perform gas phase analysis. Respectively record the peak area ratios (Ai / As, where Ai represents the chromatographic peak area of the analyte and As represents the chromatographic peak area of the standard substance) of the analytes (furfural, furan, 2-methylfuran, tetrahydrofuran, 2-methyltetrahydrofuran, furfuryl alcohol, and tetrahydrofurfuryl alcohol) and the standard substance n-heptanol as the abscissa, calculate the mass ratios mi / ms of furfural, furan, 2-methylfuran, tetrahydrofuran, 2-methyltetrahydrofuran, furfuryl alcohol, tetrahydrofurfuryl alcohol, and n-heptanol in each solution as the ordinate, draw the standard working curve of raw materials and products, and calculate the amount of products; Quantitative analysis of reaction gas products: A Panolen gas chromatograph was connected online with a fixed bed reactor (with a TCD\FID hydrogen flame detector), and the products of CO, C2, C3, C4, furan, 2-methylfuran, tetrahydrofuran, and 2-methyltetrahydrofuran were quantitatively analyzed by the external standard method, and the amount of products was calculated. In the following examples, the conversion rate of furfural, the selectivity and yield of furan are defined by the following formulas:

[0021]

[0022]

[0023]

[0024]

[0025] Yield of 3,4-dihydropyran (%) = Selectivity of 3,4-dihydropyran * Conversion rate of tetrahydrofurfuryl alcohol * 100

[0026] Yield of tetrahydropyran (%) = Selectivity of tetrahydropyran * Conversion rate of tetrahydrofurfuryl alcohol * 100

[0027] Selectivity of 2 - Hydroxytetrahydropyran (%) = Selectivity of 2 - Hydroxytetrahydropyran * Conversion of Tetrahydrofurfuryl Alcohol * 100

[0028] Preparation of Catalyst in Example A1

[0029] The specific preparation steps of the catalyst are as follows:

[0030] (1) Weigh 1.0 g of palladium chloride solid and dissolve it in 1.0 g of concentrated hydrochloric acid, then dilute it with water to 1000 mL to prepare an aqueous solution with a palladium concentration of 3.33 mmol / L.

[0031] (2) Pipette 7.0 mL (0.0233 mmol of palladium) of the aqueous solution containing the active component palladium, and dilute it with water to 40 mL; then add polyvinylpyrrolidone (PVP, MW = 58000) (0.466 mmol), and then add 10 mL of ethylene glycol dissolved in the aqueous solution, and stir vigorously for 1 hour to prepare an impregnation solution of active metal palladium.

[0032] (3) Add 1.0 g of γ - Al 2 O 3 (20 - 40 mesh) to the impregnation solution of active metal Pd, shake it at 60 °C for 5 hours, and then cool it to room temperature; filter and wash the obtained solid, dry it under vacuum at 25 °C for 12 hours, and dry it in an oven at 110 °C for 12 hours.

[0033] (4) Dissolve 0.1 g of potassium carbonate in 1.2 g of water, impregnate the catalyst precursor loaded with the active component palladium dried in step (3) for 6 hours, dry it at 120 °C for 12 hours, and calcine it at 400 °C for 4 hours to obtain Catalyst 1#, with the loading amount of palladium relative to the carrier being 0.25%, and the loading amount of potassium salt relative to the carrier being 10%. After the obtained catalyst is reduced, it is characterized by transmission electron microscopy (TEM), and it is found that the particle size distribution range of metallic palladium is 2 - 5 nm, and almost no agglomerated large particles are formed.

[0034] Example A2: Pipette 8.5 mL (0.0283 mmol of Pd) of the aqueous solution containing the active component palladium, dilute it with water to 40 mL, and the others (processes and conditions) are the same as in Example A1 to obtain Catalyst 2#, with the loading amount of palladium relative to the carrier being 0.30%, and the loading amount of potassium salt relative to the carrier being 10%.

[0035] Example A3: Pipette 5.5 mL (0.0183 mmol of Pd) of the aqueous solution containing the active component palladium, dilute it with water to 40 mL, and the others (processes and conditions) are the same as in Example A1 to obtain Catalyst 3#, with the loading amount of palladium relative to the carrier being 0.19%, and the loading amount of potassium salt relative to the carrier being 10%.

[0036] Example A4: Pipette 4.5 mL of an aqueous solution containing the active component palladium (0.0150 mmol Pd), dilute it with water to 40 mL, and the other (process and conditions) are the same as in Example A1, to obtain catalyst 4#. The loading amount of palladium relative to the support is 0.16%, and the loading amount of potassium salt relative to the support is 10%.

[0037] Example A5: Weigh 0.01 g of potassium carbonate, and the other (process and conditions) are the same as in Example A1, to obtain catalyst 5#. The loading amount of palladium relative to the support is 0.25%, and the loading amount of potassium salt relative to the support is 1.0%.

[0038] Example A6: Weigh 0.05 g of potassium carbonate, and the other (process and conditions) are the same as in Example A1, to obtain catalyst 6#. The loading amount of palladium relative to the support is 0.25%, and the loading amount of potassium salt relative to the support is 5.0%.

[0039] Example A7: Weigh 0.15 g of potassium carbonate, and the other (process and conditions) are the same as in Example A1, to obtain catalyst 7#. The loading amount of palladium relative to the support is 0.25%, and the loading amount of potassium salt relative to the support is 15%.

[0040] Example A8: Weigh 0.2 g of potassium carbonate, and the other (process and conditions) are the same as in Example A1, to obtain catalyst 8#. The loading amount of palladium relative to the support is 0.25%, and the loading amount of potassium salt relative to the support is 20%.

[0041] Example A9: Polyvinylpyrrolidone (PVP, MW = 3500), and the other (process and conditions) are the same as in Example A1, to obtain catalyst 9#. The loading amount of palladium relative to the support is 0.25%, and the loading amount of potassium salt relative to the support is 10%.

[0042] Example A10: Polyvinylpyrrolidone (PVP, MW = 37900), and the other (process and conditions) are the same as in Example A1, to obtain catalyst 10#. The loading amount of palladium relative to the support is 0.25%, and the loading amount of potassium salt relative to the support is 10%.

[0043] Example A11: Weigh 0.93 g of palladium nitrate dihydrate (Shanghai Makailin Company), and then dilute it with water to 1000 mL to prepare an aqueous solution with a palladium concentration of 3.33 mmol / L. The other (process and conditions) are the same as in Example A1, to obtain catalyst 11#. The loading amount of palladium relative to the support is 0.25%, and the loading amount of potassium salt relative to the support is 10%.

[0044] Preparation of Catalyst in Example A12

[0045] The specific preparation steps of the catalyst are as follows:

[0046] (1) Weigh 1.75 g of chloroplatinic acid hexahydrate (Sigma-Aldrich), dilute it with water to 1000 mL to prepare an aqueous solution with a platinum concentration of 3.36 mmol / L.

[0047] (2) Pipette 7.0 mL (0.0233 mmol Pd) of the aqueous solution containing the active component platinum, and dilute it with water to 40 mL; then add polyvinylpyrrolidone (PVP, MW = 58000) (0.466 mmol), and then add 10 mL of ethylene glycol dissolved in the aqueous solution, and stir vigorously for 1 hour to prepare an impregnation solution of active metal platinum.

[0048] (3) Add 1.0 g of γ-Al 2 O 3 (20 - 40 mesh) to the impregnation solution of active metal platinum, shake it at 60 °C for 5 hours, and then cool it to room temperature; filter and wash the obtained solid, dry it under vacuum at 25 °C for 12 hours, and dry it in an oven at 110 °C for 12 hours.

[0049] (4) Dissolve 0.1 g of potassium carbonate in 1.2 g of water, impregnate the catalyst precursor loaded with active component platinum dried in step (3) for 6 hours, dry it at 120 °C for 12 hours, and calcine it at 400 °C for 4 hours to obtain catalyst 12#, with a theoretical platinum loading of 0.25% and a theoretical potassium salt loading of 10%.

[0050] Example A13: Weigh 3.64 g of platinum nitrate solution (Shanghai Aladdin Biochemical Technology Co., Ltd.), dilute it with water to 1000 mL to prepare an aqueous solution with a platinum concentration of 3.36 mmol / L; other operations are the same as in Example A12 to obtain catalyst 13#, with a theoretical platinum loading of 0.25% and a theoretical potassium salt loading of 10%.

[0051] Comparative Example 1: Weigh 11.0 mL of palladium chloride solution (1.0 g of palladium chloride dissolved in 250 mL of dilute hydrochloric acid with a concentration of 49.8 mmol / L), put 10 g of activated Al 2 O 3 balls (crushed and screened to 20 - 40 mesh) produced by Shandong Wuhua New Materials Technology Co., Ltd. into the above solution for impregnation for 8 hours, dry it at 120 °C for 12 hours, and calcine it at 400 °C for 4 hours; weigh 1.0 g of potassium carbonate, dissolve it in 11.2 g of pure water, impregnate the above-mentioned Al 2 O 3 balls loaded with palladium for 8 hours, dry it at 120 °C for 12 hours, and calcine it at 400 °C for 4 hours; reduce it at 200 °C for 2 h under a hydrogen atmosphere to obtain catalyst 14#, with a theoretical palladium loading of 0.25% and a theoretical potassium salt loading of 10%. After the obtained catalyst is reduced, it is characterized by transmission electron microscopy (TEM), and it is found that the particle size distribution range of metallic palladium is 5 - 10 nm, and a few particle sizes grow to about 20 nm.

[0052] Examples B1 - B13

[0053] The catalysts obtained above were evaluated on a fixed - bed reactor with an inner diameter of 7 mm. The reaction was carried out at atmospheric pressure, the reaction temperature was 265 °C, and the mass hourly space velocity of furfural feed was 3.48 h -1 (volumetric hourly space velocity 2.22 h -1 ). The molar ratio of hydrogen to furfural was 2.46, and the running time was 12 hours. The evaluation results are shown in Table 1. It can be seen from Examples B1 - B4 in Table 1 that when the palladium loading was 0.25%, both the furfural conversion rate and the furan selectivity reached the highest. It can be seen from Examples B1, B5 - B8 that when the addition amount of the promoter component was less than 1%, the furan selectivity decreased, and when the addition amount was higher than 20%, the furfural conversion rate decreased. By comparing Example B1 and Comparative Example 1, it can be seen that the catalyst prepared by the colloid method for the active metal impregnating solution has higher activity than the conventional equal - volume impregnation method with an aqueous solution, probably because the metal ion particle size is smaller and the distribution is more uniform.

[0054] Furfural was heated to 40 - 150 °C in a vaporizer and then entered the catalyst bed of the fixed - bed reactor together with hydrogen. Furfural underwent a decarbonylation reaction on the catalyst to produce furan. The liquid raw material and the product were collected by low - temperature condensation after reaction, and the gas product was quantitatively analyzed by on - line chromatography.

[0055]

[0056]

[0057] Reaction process of Examples B14 - B20

[0058] The catalyst of Example 1 - 1# changed the reaction conditions, and the running time was 12 hours. The results are shown in Table 2: It can be seen from Examples B1, B14 - B16 that when the furfural feed space velocity was higher than 4.64 h -1 , furfural could not be completely converted. Considering the industrial cost of subsequent product separation and purification, a space velocity of 2.32 h -1 was more appropriate. It can be seen from Examples B15, B18 - 19 that at a reaction temperature of 300 °C, furfural was completely converted, which was more suitable. It can be seen from Examples B17, B20 - B21 in Table 2 that a hydrogen - to - furfural molar ratio of 0.67 - 7.39 was more suitable, and furfural decarbonylation to furan had excellent performance. Considering that hydrogen has the function of cleaning the coking substances on the catalyst surface, therefore, too small a hydrogen - to - furfural ratio will affect the service life of the subsequent catalyst.

[0059]

[0060]

[0061] Example B22

[0062] Under the same reaction process conditions as in Example B17, the long-term stability test of Catalyst 1# was carried out. The products at the outlet of the hydrogenation reactor were collected for analysis, and the analysis results are shown in Table 3. It can be seen from the data in Table 3 that the catalyst has good stability. After 800 h of reaction, the furfural conversion rate still reaches 92.0%, and the furan selectivity is 97.8. This may be due to the fact that the metal ion particle size of the catalyst prepared by the colloid method is smaller and the distribution is more uniform, which improves the coke resistance and sintering resistance of the catalyst. This is the main reason for the long catalyst life.

[0063]

[0064] The above content is a further detailed description of the present invention in combination with specific preferred embodiments. It cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention belongs, without departing from the concept of the present invention, several simple deductions and substitutions can still be made, which should all be regarded as belonging to the protection scope of the present invention.

Claims

1. A catalyst for the gas-phase decarbonylation of furfural to furan, characterized in that: the catalyst comprises a support and an active component and a promoter component supported on the support; the support is at least one or more of alumina, silica, titanium oxide, zinc oxide, cerium oxide; the active component is at least one or more of noble metals Pd, Pt, Ru, and the mass is 0.15-0.3% (preferably 0.18-0.25%) of the mass of the support; the promoter component is one or both of potassium and sodium, and potassium or sodium exists in the form of one or more of oxides or salts, and the loading amount of the promoter is 1.0-20% (preferably 5.0-10%) of the mass of the support.

2. A method for preparing the catalyst according to claim 1, characterized in that: the active component of the catalyst is prepared by a colloid method and impregnated on the support; the specific preparation steps of the catalyst are as follows: (1) First, a noble metal salt is configured into a 1000 ml aqueous solution, and the noble metal concentration is 0.1-10.0 mmol / L (preferably 1.0-5.0 mmol / L); (2) Then, 1.0-20.0 ml of the noble metal solution is taken and diluted with water to 40 ml, polyvinylpyrrolidone (the molar ratio of PVP to the noble metal is 5:1-50:1, preferably 10:1-30:1) is added, and then 5-50 mL of ethylene glycol is dissolved in the solution and stirred to obtain an active metal impregnation solution; (3) Then, activated alumina (0.1-10 g, preferably 0.5-5.0 g) is added to the active metal impregnation solution, shaken at 25-100 °C for 2-24 hours, and then cooled to room temperature; the obtained solid is filtered, washed, dried under vacuum at 25-60 °C for 8-24 hours, and dried in air at 80-150 °C for 8-48 hours; (4) Potassium salt and / or sodium salt are dissolved in 0.1-12 g of water, and the catalyst precursor loaded with the active component noble metal dried in step (3) is impregnated for 0.5-12 hours, dried at 80-150 °C for 8-48 hours, and calcined at 200-700 °C for 1-12 hours to obtain the catalyst.

3. The method for preparing the catalyst according to claim 2, characterized in that: the noble metal palladium salt is at least one of palladium chloride, palladium nitrate, palladium acetate, chloropalladic acid, sodium chloropalladate, ammonium chloropalladate; the noble metal platinum salt is at least one or more of chloroplatinic acid, platinum tetrachloride, platinum nitrate, platinum acetylacetonate; the salt solution of potassium or sodium is at least one or more of carbonate, acetate, sulfate, nitrate, chloride.

4. The method for preparing the catalyst according to claim 2, characterized in that: the molecular weight of the polyvinylpyrrolidone is 3000-700000.

5. Application of the catalyst according to claim 1 in the catalytic gas-phase decarbonylation of furfural to furan.

6. The application according to claim 5, characterized in that: The reaction conditions for the decarbonylation of furfural to furan are as follows: at atmospheric pressure, the reaction temperature is 250 - 360 °C (preferably 280 - 320 °C), and the mass space velocity of furfural feed is 0.5 - 5.0 h -1 (preferably 1.2 - 3.5 h -1 ), and the molar ratio of hydrogen to furfural is 0.6 - 7.5:1 (preferably 1.5 - 4.5:1).

7. The application according to claim 5 or 6, characterized in that: The furfural decarbonylation reaction proceeds according to the following steps: Furfural is heated to 40 - 150 °C in a vaporizer and then enters the catalyst bed of a fixed-bed reactor together with hydrogen. The furfural undergoes a decarbonylation reaction on the catalyst to produce furan. The liquid raw materials and products are collected as reaction liquid after low-temperature condensation, and the gas products are quantitatively analyzed by on-line chromatography.

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