Reduction-state noble metal catalyst as well as preparation method and application thereof

Abstract

The invention provides a reduced noble metal catalyst as well as a preparation method and application thereof. The preparation method comprises the following steps: mixing a noble metal precursor, water and a reducing solvent, and preparing a composite dipping solution with the same adsorption quantity as a carrier; carrying out first vacuumizing on the carrier, and pumping a composite dipping solution with the same adsorption quantity as the carrier into the vacuumized carrier; then, second vacuumizing continues to be carried out, and vacuumizing is stopped; vacuumizing is recovered, the carrier is heated, and third vacuumizing is carried out synchronously; heating and vacuumizing are stopped, and normal pressure is recovered; and drying the product to obtain the reduced noble metal catalyst. A one-step precious metal saturated impregnation-reduction method is adopted, the processes of precious metal impregnation, reduction, reducing agent removal and the like are completed by adding two components of reducing functional groups into precious metal impregnation liquid and combining vacuum programmed heating impregnation, the reduction-state precious metal is uniformly loaded on carriers such as a molecular sieve, and the performance of the catalyst is improved.

Description

Technical Field

[0001] This invention belongs to the fields of petrochemicals and precious metal catalysts, specifically relating to a reduced precious metal catalyst, its preparation method, and its application. Background Technology

[0002] Noble metals are widely used in the preparation of hydrogenation catalysts due to their high hydrogenation and dehydrogenation activity, such as bifunctional supported noble metal catalysts for the hydroisomerization of n-alkanes. In these catalysts, the molecular sieve support provides acidity and suitable pores, as well as isomerization active sites and reaction and diffusion environments. The noble metal active center plays the role of hydrogenation and dehydrogenation. Its dosage, dispersion effect, and preparation process determine the catalyst cost. Furthermore, the hydrogenation and dehydrogenation reactions of the noble metal active center, as intermediate steps in the hydroisomerization process, determine the reactivity and selectivity of the hydroisomerization reaction, as well as the catalyst's lifespan. Therefore, a highly dispersed noble metal loading method is a key technology determining the cost and performance of catalysts.

[0003] In existing technologies, catalysts prepared using conventional impregnation and loading methods suffer from poor dispersion of precious metals and are prone to agglomeration during calcination, resulting in low utilization rates and excessive amounts of precious metals. Furthermore, the catalysts require reduction of the precious metal oxides before use to acquire activity. Simultaneously, the hydrogenation and dehydrogenation activities of the catalysts are mismatched with their isomerization activities, affecting the overall performance of the catalysts. Moreover, during calcination, the metals in catalysts after solution saturation impregnation and loading tend to aggregate, further impacting the efficiency of precious metal utilization. Further, after catalyst preparation, the precious metal oxides need to be reduced to a reduced state using a reducing atmosphere or reducing solvent. Reduction outside the reactor is complex; while reduction inside the reactor results in slow heating and failure to reach the reduction temperature due to the low heat capacity of reducing gases such as hydrogen, affecting catalyst activity and start-up progress.

[0004] CN111215053A describes a process where a precursor of a noble metal, consisting of chlorides, nitrates, or organic complexes, is dissolved in deionized water and / or organic solvents such as methanol, ethanol, acetone, or toluene. This precursor is then impregnated onto a support and dried at 60-120℃ for 6-24 hours to obtain a supported noble metal catalyst precursor. The obtained supported noble metal catalyst precursor is then placed in an atmosphere containing 1%-50% H2 (by volume) and reduced at 100℃-400℃ for 30-300 minutes to obtain a supported nano- or sub-nano-scale noble metal catalyst. Finally, the obtained supported nano- or sub-nano-scale noble metal catalyst is placed in one or more of the following atmospheres (by volume) containing 0.1%-100% CO, NO, NO2, NH3, CH3I, CH3Br, CH3Cl, C2H5I, C2H5Br, or C2H5Cl and treated at 150℃-400℃ for 1-600 minutes to obtain a supported single-atom dispersed noble metal catalyst. However, the atmosphere used in the preparation of the above catalysts is relatively complex, and a separate reduction step is required, making it difficult to scale up the preparation process industrially.

[0005] CN111135840B describes a process where a noble metal precursor is dissolved in deionized water or a common organic solvent, and then an appropriate amount of common inorganic or organic reagents containing N, P, and S are added to obtain a noble metal precursor complex solution (the mass concentration of the noble metal is 0.0001%-5%). A certain amount of support is impregnated in the noble metal precursor complex solution, stirred for 1-600 minutes, filtered, and dried at 60-120℃ for 6-12 hours to obtain a noble metal catalyst precursor. A certain amount of the above catalyst precursor is placed in an atmosphere such as He, Ar, N2, H2, O2, or air and treated at 200℃-800℃ for 10-600 seconds to obtain a supported single-atom dispersed noble metal catalyst. However, the added inorganic or organic reagents containing N, P, and S do not burn completely in He, Ar, N2, or H2 atmospheres, and the residue of N, P, and S elements can easily poison and deactivate the catalyst. Metal aggregation can also easily occur during the calcination process, and the catalyst needs to be reduced before use.

[0006] CN113101969A describes a reaction in which molecular sieves are mixed with a water-soluble metal salt solution in a reactor. The solvent for the metal salt solution is selected from at least one of water, methanol, ethanol, propanol, isopropanol, and butanol. The reaction temperature is 60-150℃, and the reaction time is 2-10 days. Unreacted metal salts are removed by filtration or centrifugation to obtain solid filter blocks, which are then calcined at 500-650℃ for 2-12 hours to prepare a catalyst. However, the reaction time of 2-10 days is too long, resulting in low preparation efficiency. The prepared product needs to be calcined at high temperatures, making the preparation process complex. Furthermore, the metal is prone to aggregation, and the calcined catalyst requires reduction and activation before use, making the preparation process lengthy.

[0007] CN105688979A first prepared Pt nanoparticles using the ethylene glycol reduction method; then, it used the sol-gel method to load the Pt nanoparticles onto a TiO2 & SAPO-11 composite support, resulting in a hydroisomerization catalyst with a Pt content of 0.1%-1%. The metal active component exhibited good dispersion, leading to excellent conversion and isomerization selectivity. However, this method requires the prior preparation of a nanoparticle sol-gel, a complex process involving heating and reflux, making it difficult to implement industrially. Furthermore, the loaded catalyst requires calcination, which can lead to metal agglomeration.

[0008] For precious metal catalysts, due to the high price of precious metals, their dispersion effect and loading on the supported catalyst, as well as the preparation process, directly affect the performance and cost of the catalyst.

[0009] Therefore, how to uniformly load precious metals onto the catalyst support and avoid subsequent roasting and reduction steps is an urgent problem to be solved. Summary of the Invention

[0010] To address the aforementioned technical problems, the present invention aims to provide a reduced noble metal catalyst, its preparation method, and its application. By controlling the reducing functional group composition in the noble metal impregnation solution and combining it with a vacuum heating impregnation method, the loading and reduction of the noble metal are achieved in one step, yielding a reduced noble metal catalyst that can be used in hydroisomerization reactions.

[0011] To achieve the above objectives, the present invention provides a method for preparing a reduced noble metal catalyst, wherein the preparation method includes:

[0012] (1) Mix the noble metal precursor, water and reducing solvent to prepare a composite impregnation solution with an adsorption capacity equal to that of the carrier.

[0013] (2) Perform a first vacuum on the carrier, and then inject a composite impregnation solution equal to the amount of adsorption on the carrier into the vacuumed carrier; then perform a second vacuum, and then stop the vacuum.

[0014] (3) Restore the vacuum and heat the carrier obtained in step (2) while simultaneously performing a third vacuum.

[0015] (4) Stop heating and vacuuming, and restore to normal pressure; after drying, the product is obtained as a reduced noble metal catalyst;

[0016] The reducing solvent comprises a first reducing component and a second reducing component; the first reducing component is a component containing a hydroxyl functional group; the second reducing component is a component containing an amino and / or thiol functional group; the mass ratio of water to the reducing solvent is 1:10 to 10:1 (preferably 1:5 to 5:1); based on 100% of the mass of the reduced noble metal catalyst, the mass content of the noble metal precursor, in elemental form, is 0.05%-1% (preferably 0.1%-0.5%).

[0017] According to a specific embodiment of the present invention, preferably, the mass ratio of the first reducing component to the second reducing component is 1:5 to 5:1; more preferably, it is 1:2 to 2:1. In this invention, by utilizing the difference in reduction performance between the two-component reducing agents, the easily reduced and difficult-to-reduce components in the active component can be reduced in stages, thereby improving the reduction effect and catalytic performance.

[0018] According to a specific embodiment of the present invention, preferably, the first reducing component includes one or more of methanol, ethanol, ethylene glycol, phenol, etc.; more preferably, it is ethylene glycol.

[0019] According to a specific embodiment of the present invention, preferably, the second reducing component includes one or more of aniline, L-cysteine, tyrosine, hydrazine hydrate, etc.; more preferably, it is aniline.

[0020] According to a specific embodiment of the present invention, preferably, the noble metal precursor is a Group VIII metal, including one or more combinations of acids, salts, complexes, or organic compounds formed by Ru, Rh, Pd, Os, Ir, and Pt; more preferably, the Group VIII metal is Pt and / or Pd.

[0021] According to a specific embodiment of the present invention, preferably, the heating temperature is 80-120℃ (preferably 100-110℃); more preferably, the heating is oil bath heating.

[0022] In some specific implementations, preferably, the specific amount of the composite impregnation solution added, which is equal to the amount of carrier adsorption, is determined by the carrier solvent absorption rate. For example, the amount of carrier adsorption is first obtained by measuring the carrier solvent absorption rate, and then the amount of composite impregnation solution is determined. The method for measuring the carrier solvent absorption rate includes: soaking a certain mass of dry carrier in an excess of mixed impregnation solvent for 2 hours to allow the carrier to fully adsorb the impregnation solvent, then taking out the saturated carrier, dispersing it on a glass funnel until the free solvent on the surface is drained, weighing the carrier, calculating the amount of adsorbed solvent, and dividing it by the weight of the dry carrier to obtain the solvent absorption rate.

[0023] In some specific embodiments, preferably, the first vacuuming time is 0.5-5 hours (preferably 1-2 hours), and the vacuum degree is 0.5 bar-0.01 bar (preferably 0.2 bar-0.1 bar). In this invention, the first vacuuming operation can remove the air adsorbed in the catalyst pores and form a negative pressure in the pores. When the impregnation liquid is drawn in, the impregnation liquid diffuses more easily under the action of the internal and external pressure difference, thereby ensuring better metal dispersion.

[0024] In some specific embodiments, preferably, the second vacuuming time is 0.5-5 hours (preferably 1-2 hours), and the vacuum level is 0.5 bar-0.01 bar. In this invention, the solution is drawn in using negative pressure during the second vacuuming, which can promote the diffusion of the solution into the pores.

[0025] In some specific embodiments, preferably, the third vacuuming time is 0.5-5 hours (preferably 1-2 hours), and the vacuum degree is 0.5 bar-0.1 bar. In this invention, the third vacuuming, under heating conditions, lowers the boiling points of the solvent and reducing agent, and begins to diffuse outward from the catalyst. At the same time, the flowing diffusion of the reducing agent allows for better contact with the active metal, resulting in more complete reduction of the metal.

[0026] In some specific implementations, preferably, the vacuum stop time is 0.2-2 hours, more preferably 0.5-1 hour.

[0027] In some specific embodiments, preferably, the product is dried at a temperature of 80-150°C for 10-24 hours (preferably 10-12 hours).

[0028] In the above preparation method, preferably, the preparation method of the reduced noble metal catalyst specifically includes the following steps: determining the solvent absorption rate of the above support; according to the solvent absorption rate of the support, preparing a composite impregnation solution with the noble metal precursor, water, and a solvent containing reducing functional groups; placing the support in a container and evacuating for 0.5-5.0 h; evacuating the composite impregnation solution into the evacuated support within 1-10 min; after evacuating the composite impregnation solution, continuing to evacuate for 0.5-5.0 h, then stopping the vacuum for 0.5-2 h; continuing to evacuate again, and placing the container holding the support in an oil bath, continuing to evacuate for 0.5-5.0 h; after the time is reached, stopping heating and evacuation, and restoring the pressure to atmospheric pressure; taking out the obtained product and drying it at 120℃ for 10-24 h to obtain the reduced noble metal catalyst.

[0029] According to a specific embodiment of the present invention, preferably, the carrier is obtained by mixing porous material, extrusion aid, acid and water, kneading and extruding into strips, and then drying and calcining.

[0030] According to a specific embodiment of the present invention, preferably, the porous material includes molecular sieves and / or inorganic porous materials.

[0031] According to a specific embodiment of the present invention, preferably, the molecular sieve includes one or more combinations of ten-membered ring and / or twelve-membered ring one-dimensional porous molecular sieves and their eutectic materials.

[0032] In some specific embodiments, preferably, the molecular sieve includes one or more combinations of SAPO-11, SAPO-31, SAPO-41, ZSM-22, ZSM-23, ZSM-48, ZSM-12, etc.

[0033] According to a specific embodiment of the present invention, preferably, the inorganic porous material includes one or more of alumina, silicon dioxide, amorphous aluminum silicate, porous carbon, and pseudoboehmite; more preferably, it is alumina.

[0034] In some specific embodiments, preferably, the extrusion aid includes one or more of the following: guar gum powder, methylcellulose, soluble starch, etc.; more preferably, it is guar gum powder.

[0035] In some specific embodiments, preferably, the acid includes one or more of hydrochloric acid, nitric acid, phosphoric acid, sulfuric acid, formic acid, acetic acid, citric acid, oxalic acid, etc.; more preferably, it is nitric acid.

[0036] In some specific embodiments, preferably, the mass concentration of the acid solution is 5%-50%, more preferably 5%-10%.

[0037] In some specific implementations, preferably, the porous material is a molecular sieve and an inorganic porous material. Before the porous material, extrusion aid, acid, and water are mixed, the molecular sieve in the porous material is first roasted and pulverized in sequence.

[0038] In some specific embodiments, preferably, the method for preparing the carrier includes the following steps:

[0039] (1) The molecular sieve powder is calcined in air at 500-600℃ for 10-24h and then pulverized to 100-300 mesh.

[0040] (2) The treated molecular sieve is thoroughly mixed with inorganic porous material (preferably crushed inorganic porous material) and extrusion aid, then acid and deionized water are added, and the mixture is thoroughly mixed and kneaded and extruded into strips. The strips are dried at 100-120℃ (preferably 120℃) for 10-50h (preferably 10-12h). The water content of the carrier after drying is 0.1-5.0% by mass.

[0041] (3) The dried support is calcined in air at 500-600℃ for 6-12h (preferably 6-8h) to obtain the catalyst support.

[0042] The present invention also provides a reduced noble metal catalyst, wherein the reduced noble metal catalyst is prepared by the above-described preparation method.

[0043] This invention also provides the application of the above-mentioned reduced noble metal catalyst in hydroisomerization reactions.

[0044] According to a specific embodiment of the present invention, preferably, the feedstock for the hydroisomerization reaction is a waxy oil; more preferably, the waxy oil includes alkanes and / or hydrocracking tail oil.

[0045] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0046] (1) The method for preparing reduced noble metal catalyst provided by the present invention adopts a one-step noble metal saturated impregnation-reduction method. By adding a two-component reducing functional group to the noble metal impregnation solution and combining it with vacuum temperature program impregnation, the processes of noble metal impregnation, reduction and removal of reducing agent are completed, so as to realize that the reduced noble metal is uniformly loaded on the molecular sieve and other supports, improve the catalyst performance and effectively reduce the catalyst preparation cost.

[0047] (2) The method for preparing reduced noble metal catalyst provided by the present invention simplifies the conventional impregnation, calcination and reduction steps into one step. The obtained catalyst does not require subsequent calcination and reduction steps, effectively preventing the aggregation of active metals during the calcination process. It can shorten the start-up process and improve start-up efficiency while ensuring the activity of the catalyst. Attached Figure Description

[0048] Figure 1 H2-TPR curves of the reduced noble metal catalysts prepared in Examples 1-2.

[0049] Figure 2 H2-TPR curves of the reduced noble metal catalysts prepared for comparative examples 1-2. Detailed Implementation

[0050] In order to provide a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail below, but it should not be construed as limiting the scope of implementation of the present invention.

[0051] Example 1:

[0052] This embodiment provides a method for preparing a reduced noble metal catalyst, including the following steps:

[0053] ZSM-22 molecular sieve raw powder was calcined at 550℃ for 24 hours, and then pulverized to 200-300 mesh. 50g of pulverized molecular sieve, 17g of boehmite, 3g of guar gum powder, 23g of 10% nitric acid solution, and 16g of deionized water were mixed, kneaded and extruded into strips, dried at 120℃ for 24 hours, and calcined in air at 550℃ for 8 hours to obtain the catalyst support.

[0054] Prepare a composite impregnation solution by taking 5g of water, 20g of ethylene glycol, 10g of aniline and 0.67g of chloroplatinic acid. Take 50g of catalyst support, and evacuate the vacuum for 2 hours at a vacuum degree of 0.1 bar. Then, evacuate the composite impregnation solution into the support within 1-10 minutes, and continue the second vacuum impregnation for 1 hour (vacuum degree of 0.1 bar). Then stop evacuating the vacuum for 1 hour.

[0055] The vacuum was restored, and the container holding the substance was placed in a 100°C oil bath for heating, while a third vacuum was performed for 2 hours (vacuum degree 0.2 bar); until the solvent was evaporated and the pressure was restored to normal, the product was taken out and dried at 120°C for 12 hours to obtain a reduced noble metal catalyst, which was used for hydroisomerization reaction.

[0056] Example 2:

[0057] This embodiment provides a method for preparing a reduced noble metal catalyst, including the following steps:

[0058] ZSM-22 molecular sieve raw powder was calcined at 550℃ for 24 hours, and then pulverized to 200-300 mesh. 50g of pulverized molecular sieve, 17g of boehmite, 3g of guar gum powder, 23g of 10% nitric acid solution, and 16g of deionized water were mixed, kneaded and extruded into strips, dried at 120℃ for 24 hours, and calcined in air at 550℃ for 8 hours to obtain the catalyst support.

[0059] Prepare a composite impregnation solution by taking 5g of water, 20g of ethylene glycol, 10g of aniline and 0.14g of chloroplatinic acid. Take 50g of catalyst support, and evacuate the vacuum for 2 hours at a vacuum degree of 0.5 bar. Then, evacuate the composite impregnation solution into the support within 1-10 minutes, and continue the second vacuum impregnation for 1 hour (vacuum degree of 0.05 bar). Then stop evacuating the vacuum for 1 hour.

[0060] The vacuum was restored, and the container holding the substance was placed in a 100°C oil bath for heating, while a third vacuum was performed for 2 hours (vacuum degree 0.2 bar); until the solvent was evaporated and the pressure was restored to normal, the product was taken out and dried at 120°C for 12 hours to obtain a reduced noble metal catalyst, which was used for hydroisomerization reaction.

[0061] Example 3:

[0062] This embodiment provides a method for preparing a reduced noble metal catalyst, including the following steps:

[0063] ZSM-22 molecular sieve raw powder was calcined at 550℃ for 24 hours, and then pulverized to 200-300 mesh. 50g of pulverized molecular sieve, 17g of boehmite, 3g of guar gum powder, 23g of 10% nitric acid solution, and 16g of deionized water were mixed, kneaded and extruded into strips, dried at 120℃ for 24 hours, and calcined in air at 550℃ for 12 hours to obtain the catalyst support.

[0064] Prepare a composite impregnation solution by taking 20g water, 10g ethanol, 5g L-cysteine ​​and 0.40g chloroplatinic acid. Take 50g catalyst support, and evacuate the vacuum at 0.01 bar for 2 hours. Then, evacuate the composite impregnation solution into the support within 1-10 minutes. Continue evacuation for 1 hour (vacuum degree 0.1 bar) and then stop evacuation for 1 hour.

[0065] The vacuum was restored, and the container holding the substance was placed in a 120°C oil bath for heating, while a third vacuum was performed for 2 hours (vacuum degree 0.5 bar); until the solvent was evaporated and the pressure was restored to normal, the product was taken out and dried at 120°C for 12 hours to obtain a reduced noble metal catalyst, which was used for hydroisomerization reaction.

[0066] Example 4:

[0067] This embodiment provides a method for preparing a reduced noble metal catalyst, including the following steps:

[0068] ZSM-23 molecular sieve raw powder was calcined at 550℃ for 24 hours, and then pulverized to 200-300 mesh. 50g of pulverized molecular sieve, 17g of boehmite, 3g of guar gum powder, 23g of 10% nitric acid solution, and 16g of deionized water were mixed, kneaded and extruded into strips, dried at 120℃ for 12 hours, and calcined at 550℃ in air for 6 hours to obtain the catalyst support.

[0069] Prepare a composite impregnation solution by taking 5g of water, 20g of ethylene glycol, 10g of aniline and 0.67g of chloroplatinic acid. Take 50g of catalyst support, and evacuate the vacuum for 1 hour at a vacuum degree of 0.1 bar. Then, evacuate the composite impregnation solution into the support within 1-10 minutes, and continue the second vacuum impregnation for 1 hour (vacuum degree of 0.1 bar). Then stop evacuating the vacuum for 1 hour.

[0070] The vacuum was restored, and the container holding the substance was placed in a 90°C oil bath for heating, while a third vacuum was performed for 5 hours (vacuum degree 0.1 bar); until the solvent was evaporated and the pressure was restored to normal, the product was taken out and dried at 120°C for 12 hours to obtain a reduced noble metal catalyst, which was used for hydroisomerization reaction.

[0071] Comparative Example 1:

[0072] This comparative example provides a method for preparing a reduced noble metal catalyst, comprising the following steps:

[0073] ZSM-22 molecular sieve raw powder was calcined at 550℃ for 24 hours, and then pulverized to 200-300 mesh. 50g of pulverized molecular sieve, 17g of boehmite, 3g of guar gum powder, 23g of 10% nitric acid solution, and 16g of deionized water were mixed, kneaded and extruded into strips, dried at 120℃ for 24 hours, and calcined in air at 550℃ for 8 hours to obtain the catalyst support.

[0074] Prepare a composite impregnation solution by taking 5g of water, 30g of ethylene glycol and 0.67g of chloroplatinic acid. Take 50g of catalyst support and evacuate the vacuum for 2 hours at a vacuum degree of 0.1 bar. Then, evacuate the composite impregnation solution into the support within 1-10 minutes and continue the second vacuum impregnation for 1 hour (vacuum degree of 0.1 bar). Then stop evacuating the vacuum for 1 hour.

[0075] The vacuum was restored, and the container holding the substance was placed in a 100°C oil bath for heating, while a third vacuum was performed for 2 hours (vacuum degree 0.2 bar); until the solvent was evaporated and the pressure was restored to normal, the product was taken out and dried at 120°C for 12 hours to obtain a reduced noble metal catalyst, which was used for hydroisomerization reaction.

[0076] Comparative Example 2:

[0077] This comparative example provides a method for preparing a reduced noble metal catalyst, comprising the following steps:

[0078] ZSM-22 molecular sieve raw powder was calcined at 550℃ for 24 hours, and then pulverized to 200-300 mesh. 50g of pulverized molecular sieve, 17g of boehmite, 3g of guar gum powder, 23g of 10% nitric acid solution, and 16g of deionized water were mixed, kneaded and extruded into strips, dried at 120℃ for 24 hours, and calcined in air at 550℃ for 8 hours to obtain the catalyst support.

[0079] Prepare an impregnation solution by taking 35g of water and 0.67g of chloroplatinic acid. Take 50g of catalyst support and apply vacuum for 2 hours at 0.1 bar. Then, apply the impregnation solution into the support within 1-10 minutes and continue the second vacuum impregnation for 1 hour (vacuum degree 0.1 bar).

[0080] The container containing the substance was heated in an oil bath at 80°C for 2 hours until the solvent was evaporated. The product was then dried at 120°C for 12 hours and calcined at 480°C for 6 hours to obtain the noble metal catalyst.

[0081] Before hydrogenation evaluation, the noble metal catalyst was reduced at 380°C for 4 hours in a hydrogen atmosphere to obtain a reduced noble metal catalyst, which was then used for the hydroisomerization reaction.

[0082] Comparative Example 3:

[0083] This comparative example provides a method for preparing a reduced noble metal catalyst, comprising the following steps:

[0084] ZSM-22 molecular sieve raw powder was calcined at 550℃ for 24 hours, and then pulverized to 200-300 mesh. 50g of pulverized molecular sieve, 17g of boehmite, 3g of guar gum powder, 23g of 10% nitric acid solution, and 16g of deionized water were mixed, kneaded and extruded into strips, dried at 120℃ for 24 hours, and calcined in air at 550℃ for 8 hours to obtain the catalyst support.

[0085] Prepare a composite impregnation solution by taking 5g of water, 30g of aniline and 0.67g of chloroplatinic acid. Take 50g of catalyst support and evacuate the vacuum for 2 hours at a vacuum degree of 0.1 bar. Then, evacuate the composite impregnation solution into the support within 1-10 minutes and continue the second vacuum impregnation for 1 hour (vacuum degree of 0.1 bar). Then stop evacuating the vacuum for 1 hour.

[0086] The vacuum was restored, and the container holding the substance was placed in a 100°C oil bath for heating, while a third vacuum was performed for 2 hours (vacuum degree 0.2 bar); until the solvent was evaporated and the pressure was restored to normal, the product was taken out and dried at 120°C for 12 hours to obtain a reduced noble metal catalyst, which was used for hydroisomerization reaction.

[0087] Comparative Example 4:

[0088] This comparative example provides a method for preparing a reduced noble metal catalyst, comprising the following steps:

[0089] ZSM-22 molecular sieve raw powder was calcined at 550℃ for 24 hours, and then pulverized to 200-300 mesh. 50g of pulverized molecular sieve, 17g of boehmite, 3g of guar gum powder, 23g of 10% nitric acid solution, and 16g of deionized water were mixed, kneaded and extruded into strips, dried at 120℃ for 24 hours, and calcined in air at 550℃ for 8 hours to obtain the catalyst support.

[0090] Prepare a composite impregnation solution by taking 5g of water, 30g of L-cysteine ​​and 0.67g of chloroplatinic acid. Take 50g of catalyst support, and evacuate the vacuum for 2 hours at a vacuum degree of 0.1 bar. Then, evacuate the composite impregnation solution into the support within 1-10 minutes, and continue the second vacuum impregnation for 1 hour (vacuum degree of 0.1 bar). Then stop evacuating the vacuum for 1 hour.

[0091] The vacuum was restored, and the container holding the substance was placed in a 100°C oil bath for heating, while a third vacuum was performed for 2 hours (vacuum degree 0.2 bar); until the solvent was evaporated and the pressure was restored to normal, the product was taken out and dried at 120°C for 12 hours to obtain a reduced noble metal catalyst, which was used for hydroisomerization reaction.

[0092] Comparative Example 5:

[0093] This comparative example provides a method for preparing a reduced noble metal catalyst, comprising the following steps:

[0094] ZSM-22 molecular sieve raw powder was calcined at 550℃ for 24 hours, and then pulverized to 200-300 mesh. 50g of pulverized molecular sieve, 17g of boehmite, 3g of guar gum powder, 23g of 10% nitric acid solution, and 16g of deionized water were mixed, kneaded and extruded into strips, dried at 120℃ for 24 hours, and calcined in air at 550℃ for 8 hours to obtain the catalyst support.

[0095] Prepare a composite impregnation solution by taking 5g of water, 30g of L-hydrazine hydrate and 0.67g of chloroplatinic acid. Take 50g of catalyst support, and evacuate the vacuum for 2 hours at a vacuum degree of 0.1 bar. Then, evacuate the composite impregnation solution into the support within 1-10 minutes, and continue the second vacuum impregnation for 1 hour (vacuum degree of 0.1 bar). Then stop evacuating the vacuum for 1 hour.

[0096] The vacuum was restored, and the container holding the substance was placed in a 100°C oil bath for heating, while a third vacuum was performed for 2 hours (vacuum degree 0.2 bar); until the solvent was evaporated and the pressure was restored to normal, the product was taken out and dried at 120°C for 12 hours to obtain a reduced noble metal catalyst, which was used for hydroisomerization reaction.

[0097] Comparative Example 6:

[0098] This comparative example provides a method for preparing a reduced noble metal catalyst, comprising the following steps:

[0099] ZSM-22 molecular sieve raw powder was calcined at 550℃ for 24 hours, and then pulverized to 200-300 mesh. 50g of pulverized molecular sieve, 17g of boehmite, 3g of guar gum powder, 23g of 10% nitric acid solution, and 16g of deionized water were mixed, kneaded and extruded into strips, dried at 120℃ for 24 hours, and calcined in air at 550℃ for 8 hours to obtain the catalyst support.

[0100] Prepare a composite impregnation solution by taking 5g water, 20g ethylene glycol, 10g aniline and 0.67g chloroplatinic acid. Take 50g catalyst support, add the composite impregnation solution directly to the support and mix evenly. Impregnate for 1 hour.

[0101] The container holding the substance was heated in an oil bath at 100°C for 2 hours and then evacuated at a vacuum of 0.1 bar until the solvent was evaporated and atmospheric pressure was restored. The product was then removed and dried at 120°C for 12 hours to obtain a reduced noble metal catalyst, which was used for hydroisomerization reaction.

[0102] The degree of reduction of the reduced noble metal catalysts in Examples 1-2 and Comparative Examples 1-2 was evaluated by performing a hydrogen temperature-programmed reduction (H2-TPR) process. The specific results are as follows:

[0103] Figure 1 The H2-TPR curves of the reduced noble metal catalysts prepared in Examples 1-2 are shown below. Figure 1 It can be seen that the catalysts prepared in Examples 1 and 2 did not show any reduction peaks before 500°C, indicating that the platinum metal was completely reduced during the loading process, and a fully reduced noble metal catalyst was obtained. The peaks around 500-550°C were generated by trace amounts of reducing agent during the TPR high-temperature reduction process, and were not caused by the catalysts prepared in this application.

[0104] Figure 2 The H2-TPR curves of the reduced noble metal catalysts prepared in Comparative Examples 1-2 are shown below. Figure 2 Comparative Example 1 shows a reduction peak at around 200℃, indicating that when impregnating precious metals, using a single component as a reducing agent (e.g., using only ethylene glycol) does not completely reduce the catalyst, and a reduction peak still exists. In contrast, Comparative Example 2, which uses a conventional method, does not introduce a reducing agent during catalyst preparation, resulting in a TPR curve with a reduction peak at both 200℃ and 350℃.

[0105] Therefore, the above Figure 1-2 The results comparison fully demonstrates the reduction effect of the catalyst using a two-component reducing agent in this invention.

[0106] The reduced noble metal catalysts prepared in Examples 1-4 and Comparative Examples 1-6 were used in hydroisomerization reactions to test the performance of the catalysts. The specific process and results are as follows:

[0107] (1) Hydroisomerization of n-dodecane

[0108] 10 mL of the reduced noble metal catalysts prepared in Examples 1-4 and Comparative Examples 1-6 were loaded into a fixed-bed reactor, and n-dodecane was reacted at a pressure of 8 MPa, a temperature of 320 °C, and a volume hourly space velocity of 1.0 h⁻¹. -1 Under the condition of a hydrogen-to-oil volume ratio of 300:1, hydroisomerization was carried out through a catalyst bed, and the evaluation results are shown in Table 1.

[0109] The conversion rate and selectivity of n-dodecane were calculated by gas chromatography analysis of the hydrogenation isomerization products; the metal dispersion was determined by CO chemical adsorption method. CO is usually adsorbed on a single metal atom. The metal dispersion was determined based on the amount of CO adsorbed and the content of the loaded metal.

[0110] Table 1. Evaluation results of n-dodecane hydroisomerization

[0111]

[0112] As can be seen from the evaluation data of n-dodecane hydroisomerization in Table 1, the catalyst prepared by the two-component reduction impregnation method of the present invention has higher metal dispersion under the same loading; under the same reaction conditions, it has higher conversion and selectivity, achieving higher metal dispersion, isomerization activity and selectivity.

[0113] (2) Hydroisomerization reaction of hydrocracking tail oil

[0114] 60 mL of the reduced noble metal catalysts prepared in Examples 1-4 and Comparative Examples 1-6 were loaded into a fixed-bed reactor, using hydrocracking tail oil as feedstock, and reacted at a pressure of 15 MPa, a temperature of 360 °C, and a volume hourly space velocity of 1.0 h⁻¹. -1 Under the condition of a hydrogen-to-oil volume ratio of 800:1, hydroisomerization was carried out through a catalyst bed. The product was then subjected to true boiling point distillation to obtain the lubricating oil base oil fraction, and the pour point, cloud point and viscosity index were analyzed. The results are shown in Table 2.

[0115] Table 2. Evaluation results of hydroisomerization of hydrocracking tail oil

[0116]

[0117] As can be seen from the hydroisomerization evaluation results of hydrocracking tail oil in Table 2, the catalyst prepared by the two-component reduction impregnation method of the present invention has a higher base oil yield, and the heavy base oil has a lower pour point and cloud point, and the product has better appearance and fluidity. At the same time, due to the high dispersion of the metal center, the metal dehydrogenation activity is better matched with the isomerization activity of the support acid, which reduces the occurrence of cracking reaction, thus resulting in a higher base oil yield.

[0118] In summary, the reduced noble metal catalyst provided by this invention has a simple preparation process, good metal dispersion, and high utilization rate. The two-component reduction impregnation method of this invention can be used to prepare supported noble metal catalysts such as alkane hydroisomerization.

Claims

1. A method for preparing a reduced noble metal catalyst, wherein, The preparation method includes: (1) Mix the noble metal precursor, water and reducing solvent to prepare a composite impregnation solution with an adsorption capacity equal to that of the carrier. (2) Perform a first vacuum on the carrier, and then inject a composite impregnation solution equal to the amount of adsorption on the carrier into the vacuumed carrier; then perform a second vacuum, and then stop the vacuum. (3) Restore the vacuum and heat the carrier obtained in step (2) while simultaneously performing a third vacuum. (4) Stop heating and vacuuming, and restore to normal pressure; after drying, the product is obtained as a reduced noble metal catalyst; The reducing solvent comprises a first reducing component and a second reducing component; the first reducing component is a component containing a hydroxyl functional group; the second reducing component is a component containing an amino and / or thiol functional group; and the mass ratio of water to the reducing solvent is 1:10 to 10:

1. Based on the mass of the reduced noble metal catalyst being 100%, the mass content of the noble metal precursor, calculated as an element, is 0.05%-1%.

2. The preparation method according to claim 1, wherein, The mass ratio of the first reducing component to the second reducing component is 1:5 to 5:

1.

3. The preparation method according to claim 1 or 2, wherein, The first reducing component includes one or more of methanol, ethanol, ethylene glycol, and phenol.

4. The preparation method according to claim 1 or 2, wherein, The second reducing component includes one or more of aniline, L-cysteine, tyrosine, and hydrazine hydrate.

5. The preparation method according to claim 1, wherein, The noble metal precursor is a group VIII metal, including one or more of the following: an acid, salt, complex, or organic compound formed by Ru, Rh, Pd, Os, Ir, and Pt.

6. The preparation method according to claim 1, wherein, The heating temperature is 80-120℃.

7. The preparation method according to claim 1, wherein, The carrier is obtained by mixing porous materials, extrusion aids, acid, and water, kneading and extruding them into strips, and then drying and calcining them.

8. The preparation method according to claim 7, wherein, The porous material includes molecular sieves and / or inorganic porous materials; The molecular sieve includes one or more of ten-membered ring and / or twelve-membered ring one-dimensional porous molecular sieves and their eutectic materials; The inorganic porous material includes one or more of the following: alumina, silicon dioxide, amorphous silica-alumina, porous carbon, and pseudoboehmite.

9. A reduced noble metal catalyst, wherein, The reduced noble metal catalyst is prepared by the preparation method described in any one of claims 1-8.

10. The application of the reduced noble metal catalyst according to claim 9 in hydroisomerization reaction; The feedstock for the hydroisomerization reaction is a waxy oil.

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