Preparation method of novel bimetallic catalyst for dehydrogenation reaction of organic liquid

Abstract

The invention is applicable to the technical field of organic liquid dehydrogenation, and provides a preparation method of a novel bimetallic catalyst for an organic liquid dehydrogenation reaction, which comprises the following steps: on a common alumina carrier, selecting different precursors to load two active components of platinum and palladium with low loading capacities through an equivalent-volume co-impregnation method; the added second component palladium has strong dehydrogenation capacity, and the palladium and platinum can form strong interaction through an electron orbital structure, so that the arrangement of particles on the carrier is improved to improve the dehydrogenation activity and stability of the catalyst and inhibit side reaction. The prepared catalyst has high stability, higher hydrogen release efficiency and long service life, and the use cost and the operation cost are effectively reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of organic liquid dehydrogenation, and in particular relates to a method for preparing a novel bimetallic catalyst for organic liquid dehydrogenation reaction. Background Art

[0002] Hydrogen contains only hydrogen atoms in its molecular structure. The carbon emissions of hydrogen as an energy source are extremely low. In addition, many large-scale processes can produce hydrogen as the main or by-product under the current circumstances, and the production problem of hydrogen has been solved. At the end of the industrial chain, that is, in the application of hydrogen, there are also directions such as fuel cells and synthetic experiments. To achieve the stable and orderly operation of the hydrogen energy industry chain, it is necessary to grasp the storage and transportation of hydrogen energy at key nodes. In the current field of hydrogen storage and transportation, commonly used hydrogen storage and release technologies such as high-pressure gas hydrogen and low-temperature liquid hydrogen have low energy density and have very high requirements for container materials, while others such as adsorption storage and release of hydrogen, metal hydride storage and release of hydrogen are immature technologies, and there are still many problems that need to be solved in the hydrogen storage and release medium. Among the hydrogen storage and release technologies, liquid organic hydrogen storage and release technology is very promising. The hydrogen storage and release medium of this technology has good stability, high safety, high hydrogen storage and release density, and can be recycled many times.

[0003] Liquid organic matter hydrogen storage and release technology must have the participation of catalysts to achieve high hydrogen release efficiency. The influence of catalysts on dehydrogenation ability is mostly in three aspects: preparation method, carrier, and active component. In order to ensure that the dehydrogenation reaction of perhydrodibenzyltoluene maintains high and stable hydrogen release efficiency, the catalytic activity of the catalyst has high requirements. Conventional single platinum-based alumina catalysts with low loading in the dehydrogenation reaction of perhydrodibenzyltoluene cannot fully meet production requirements in terms of dehydrogenation activity and stability. Summary of the invention

[0004] The purpose of the embodiments of the present invention is to provide a method for preparing a novel bimetallic catalyst for dehydrogenation reaction of an organic liquid, aiming to solve the problems raised in the above background technology.

[0005] The embodiment of the present invention is implemented as follows: a method for preparing a novel bimetallic catalyst for dehydrogenation reaction of an organic liquid comprises the following steps: Step 1: prepare the impregnation solution; The active ingredients are platinum and palladium, and the precursors are platinum chloride, chloroplatinic acid, platinum nitrate, palladium chloride, chloropalladic acid, and palladium nitrate; The volume of the impregnation liquid is equal to the saturated water absorption of the carrier, and the mass of the active components accounts for 1% of the carrier mass; Step 2, mixing and stirring the carrier and the impregnation liquid; The mixing method is to pour the carrier into the impregnation liquid, and the stirring time is 0-10h; Step 3: After the stirring is completed, the catalyst is allowed to stand for aging, and the aging time is 0-30 hours; Step 4: Dry overnight after aging at a temperature of 40-200°C; Step 5: After the catalyst is completely dried, it is calcined at a high temperature of 300-800° C. for 1-12 hours.

[0006] According to a further technical solution, in step 2, the stirring time is 0.5-8 h, more preferably, the stirring time is 1-4 h.

[0007] According to a further technical solution, in step 3, the aging time is 0.5-20 h, more preferably, the aging time is 2-12 h.

[0008] According to a further technical solution, in step 4, the drying temperature is 50-190°C, and more preferably, the drying temperature is 60-170°C.

[0009] According to a further technical solution, in step 5, the calcination temperature is 400-600° C., and the calcination time is 2-10 h. More preferably, the calcination time is 3-8 h.

[0010] Another object of the embodiment of the present invention is to provide an application of a novel bimetallic catalyst for dehydrogenation reaction of an organic liquid, wherein the novel bimetallic catalyst prepared by the above method is applied to the dehydrogenation reaction of perhydrodibenzyltoluene, and the application comprises the following steps: Step a: After calcination, the catalyst is placed in a dehydrogenation device and hydrogen is introduced for in-situ activation; The hydrogen flow rate of the activation operation is 10-500 mL / min, the activation temperature is 100-800°C, and the activation time is 1-24 h; Step b, introducing perhydrodibenzyltoluene into a dehydrogenation device and heating it to perform a dehydrogenation reaction; The reaction temperature of the dehydrogenation reaction is 280-350°C and the mass space velocity is 1-5 g 全氢二苄基甲苯 / (g 催化剂 ·h).

[0011] A further technical solution is that in step a, the hydrogen flow rate is 50-300 mL / min.

[0012] A further technical solution is that in step b, the activation temperature is 200-600°C, more preferably, the activation temperature is 300-500°C; and the activation time is 4-12h.

[0013] The present invention provides a method for preparing a novel bimetallic catalyst for dehydrogenation reaction of an organic liquid. The method uses an equal volume co-impregnation method to select two active components of platinum and palladium with low loading amounts of different precursors on a commonly used alumina carrier. The added second component palladium itself has a strong dehydrogenation ability, and palladium and platinum can also form a strong interaction through the electronic orbital structure. The arrangement of particles on the carrier is improved to improve the dehydrogenation activity and stability of the catalyst and inhibit side reactions. The prepared catalyst has high stability and higher hydrogen release efficiency, and has a long service life, which effectively reduces the use cost and operating cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The stability comparison of catalysts with different active components in Example 1 (reaction temperature 320 °C, mass space velocity g 全氢二苄基甲苯 / (g 催化剂 h)); Figure 2 Comparison of the stability of catalysts with different active components in Example 2 (reaction temperature 320 °C mass space velocity g 全氢二苄基甲苯 / (g 催化剂 h)); Figure 3 Comparison of the stability of catalysts with different active components in Example 3 (reaction temperature 320 °C mass space velocity g 全氢二苄基甲苯 / (g 催化剂 ·h)). DETAILED DESCRIPTION

[0015] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0016] The specific implementation of the present invention is described in detail below in conjunction with specific embodiments.

[0017] An embodiment of the present invention provides a method for preparing a novel bimetallic catalyst for dehydrogenation reaction of an organic liquid, comprising the following steps: Step 1: prepare the impregnation solution; The active ingredients are platinum and palladium, and the precursors are platinum chloride, chloroplatinic acid, platinum nitrate, palladium chloride, chloropalladic acid, and palladium nitrate; The volume of the impregnation liquid is equal to the saturated water absorption of the carrier, and the mass of the active components accounts for 1% of the carrier mass; Step 2, mixing and stirring the carrier and the impregnation liquid; The mixing method is to pour the carrier into the impregnation liquid, and the stirring time is 0-10h; Step 3: After the stirring is completed, the catalyst is allowed to stand for aging, and the aging time is 0-30 hours; Step 4: Dry overnight after aging at a temperature of 40-200°C; Step 5: After the catalyst is completely dried, it is calcined at a high temperature of 300-800° C. for 1-12 hours.

[0018] As a preferred embodiment of the present invention, in step 2, the stirring time is 0.5-8 h, more preferably, the stirring time is 1-4 h.

[0019] As a preferred embodiment of the present invention, in step 3, the aging time is 0.5-20 h, more preferably, the aging time is 2-12 h.

[0020] As a preferred embodiment of the present invention, in step 4, the drying temperature is 50-190°C, more preferably, the drying temperature is 60-170°C.

[0021] As a preferred embodiment of the present invention, in step 5, the calcination temperature is 400-600° C., the calcination time is 2-10 h, and more preferably, the calcination time is 3-8 h.

[0022] Another embodiment of the present invention provides an application of a novel bimetallic catalyst for dehydrogenation of an organic liquid. The novel bimetallic catalyst prepared by the above method is applied to the dehydrogenation of perhydrodibenzyltoluene, and the application comprises the following steps: Step a: After calcination, the catalyst is placed in a dehydrogenation device and hydrogen is introduced for in-situ activation; The hydrogen flow rate of the activation operation is 10-500 mL / min, the activation temperature is 100-800°C, and the activation time is 1-24 h; Step b, introducing perhydrodibenzyltoluene into a dehydrogenation device and heating it to perform a dehydrogenation reaction; The reaction temperature of the dehydrogenation reaction is 280-350°C and the mass space velocity is 1-5 g 全氢二苄基甲苯 / (g 催化剂 ·h).

[0023] As a preferred embodiment of the present invention, in step a, the hydrogen flow rate is 50-300 mL / min.

[0024] As a preferred embodiment of the present invention, in the step b, the activation temperature is 200-600°C, more preferably, the activation temperature is 300-500°C; the activation time is 4-12h.

[0025] Several specific examples are provided below to verify the effectiveness of this method.

[0026] Example 1: The modification and preparation of the platinum-based Raschig ring catalyst of the present invention are achieved by the following steps: first weigh the Raschig ring carrier, determine the water absorption rate of the carrier, prepare the impregnation solution according to the water absorption rate and the carrier mass, select platinum chloride and palladium chloride as precursors, wherein the mass ratio of platinum to palladium is 1:1, and the total mass of the active component accounts for 1% of the carrier mass; pour the carrier into the impregnation solution, stir for 2 hours, and after stirring, heat in a water bath at 40°C for 6 hours to complete aging. After the aging operation is completed, the catalyst is placed in an oven at 100°C for overnight drying, and after drying, it is placed in a muffle furnace and roasted at 500°C for 6 hours. After roasting, pure hydrogen with a flow rate of 200mL / min is introduced into the reaction device, and the temperature is raised to 300°C at a heating rate of 3°C / min, and activated at this temperature for 8 hours to obtain a bimetallic catalyst.

[0027] Take the same mass of carrier again, prepare the impregnation solution according to the water absorption rate and carrier mass, in which the mass fraction of platinum / palladium is 1%, pour the carrier into the impregnation solution, stir for 2 hours, and after stirring, heat in a water bath at 40°C for 6 hours to complete aging. After the aging operation is completed, place the catalyst in an oven at 100°C for overnight drying, and then place it in a muffle furnace for calcination at 500°C for 6 hours. After calcination, put it into the reaction device, pass pure hydrogen at a flow rate of 200mL / min, and heat it to 300°C at a heating rate of 3°C / min. Activate at this temperature for 8 hours to obtain a single metal catalyst.

[0028] The three catalysts were used to conduct an organic liquid dehydrogenation experiment, and the dehydrogenation degrees of the two catalysts were recorded at the same time. The temperature and mass space velocity were then increased to allow the reaction to proceed at a high dehydrogenation degree. The reaction lasted for 200 hours, and a sample point was taken every 40 hours to record the dehydrogenation degree. The specific experimental results are recorded in Tables 1 and Figure 1 .

[0029] Example 2: The modification and preparation of the platinum-based Raschig ring catalyst of the present invention are achieved by the following steps: first weigh the Raschig ring carrier, determine the water absorption rate of the carrier, prepare the impregnation solution according to the water absorption rate and the carrier mass, select chloroplatinic acid and chloropalladic acid as precursors, wherein the mass ratio of platinum to palladium is 3:1, and the total mass of the active component accounts for 1% of the carrier mass, pour the carrier into the impregnation solution, stir for 4 hours, and after stirring, heat in a water bath at 30°C for 10 hours to complete aging. After the aging operation is completed, the catalyst is placed in an oven at 120°C for overnight drying, and after drying, it is placed in a muffle furnace and roasted at 400°C for 4 hours. After roasting, pure hydrogen with a flow rate of 100mL / min is introduced into the reaction device, and the temperature is raised to 200°C at a heating rate of 1°C / min, and activated at this temperature for 4 hours to obtain a bimetallic catalyst.

[0030] Take the same mass of carrier again, prepare the impregnation solution according to the water absorption rate and carrier mass, in which the mass fraction of platinum / palladium is 1%, pour the carrier into the impregnation solution, stir for 4 hours, and after stirring, heat in a water bath at 30°C for 10 hours to complete aging. After the aging operation is completed, place the catalyst in an oven at 120°C for overnight drying, and then place it in a muffle furnace for calcination at 400°C for 4 hours. After calcination, put it into the reaction device, pass pure hydrogen at a flow rate of 100mL / min, and heat it to 200°C at a heating rate of 1°C / min. Activate at this temperature for 4 hours to obtain a single metal catalyst.

[0031] The three catalysts were used to conduct an organic liquid dehydrogenation experiment, and the dehydrogenation degrees of the two catalysts were recorded at the same time. The temperature and mass space velocity were then increased to allow the reaction to proceed at a high dehydrogenation degree. The reaction lasted for 200 hours, and a sample point was taken every 40 hours to record the dehydrogenation degree. The specific experimental results are recorded in Tables 1 and Figure 2 .

[0032] Example 3: The modification and preparation of the platinum-based Raschig ring catalyst of the present invention are achieved by the following steps: first weigh the Raschig ring carrier, determine the water absorption rate of the carrier, prepare the impregnation solution according to the water absorption rate and the carrier mass, select platinum nitrate and palladium nitrate as precursors, wherein the mass ratio of platinum to palladium is 1:3, and the total mass of the active component accounts for 1% of the carrier mass, pour the carrier into the impregnation solution, stir for 3 hours, and after stirring, heat in a water bath at 60°C for 12 hours to complete aging. After the aging operation is completed, the catalyst is placed in an oven at 140°C for overnight drying, and after drying, it is placed in a muffle furnace and roasted at 550°C for 8 hours. After roasting, pure hydrogen with a flow rate of 250mL / min is introduced into the reaction device, and the temperature is raised to 350°C at a heating rate of 4°C / min, and activated at this temperature for 6 hours to obtain a bimetallic catalyst.

[0033] Take the same mass of carrier again, prepare the impregnation solution according to the water absorption rate and carrier mass, in which the mass fraction of platinum / palladium is 1%, pour the carrier into the impregnation solution, stir for 3 hours, and after stirring, let it stand for 12 hours in a water bath heated at 60°C to complete aging. After the aging operation is completed, place the catalyst in an oven at 140°C for overnight drying, and then place it in a muffle furnace for calcination at 550°C for 8 hours. After calcination, put it into the reaction device, pass pure hydrogen at a flow rate of 250mL / min, and heat it to 350°C at a heating rate of 4°C / min. Activate at this temperature for 6 hours to obtain a single metal catalyst.

[0034] The three catalysts were used to conduct an organic liquid dehydrogenation experiment, and the dehydrogenation degrees of the two catalysts were recorded at the same time. The temperature and mass space velocity were then increased to allow the reaction to proceed at a high dehydrogenation degree. The reaction lasted for 200 hours, and a sample point was taken every 40 hours to record the dehydrogenation degree. The specific experimental results are recorded in Tables 1 and Figure 3 .

[0035] Table 1 Comparison of dehydrogenation results of catalysts with different active components in different embodiments

[0036] The method uses an equal volume co-impregnation method on a commonly used alumina carrier to select two active components, platinum and palladium, with low loading amounts of different precursors. The added second component palladium itself has a strong dehydrogenation ability, and palladium and platinum can also form a strong interaction through the electronic orbital structure, improve the arrangement of particles on the carrier to improve the catalyst dehydrogenation activity, stability, and inhibit side reactions.

[0037] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a novel bimetallic catalyst for dehydrogenation of organic liquid, characterized in that: The following steps are involved: Step 1: prepare the impregnation solution; The active ingredients are platinum and palladium, and the precursors are platinum chloride, chloroplatinic acid, platinum nitrate, palladium chloride, chloropalladic acid, and palladium nitrate; The volume of the impregnation liquid is equal to the saturated water absorption of the carrier, and the mass of the active components accounts for 1% of the carrier mass; Step 2, mixing and stirring the carrier and the impregnation liquid; The mixing method is to pour the carrier into the impregnation liquid, and the stirring time is 0-10h; Step 3: After stirring, the catalyst is allowed to stand for aging for 0-30 hours; Step 4: Dry overnight after aging at a temperature of 40-200°C; Step 5, after the catalyst is completely dried, it is calcined at a high temperature, the calcination temperature is 300-800°C, and the calcination time is 1-12h; In the step 2, the stirring time is 1-4 h; In step 3, the aging time is 2-12 h; In step 4, the drying temperature is 60-170°C; In the step 5, the calcination temperature is 400-600° C., and the calcination time is 3-8 h.

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