Orthoparahydrogen catalyst and preparation method thereof

Abstract

The invention discloses an ortho-parahydrogen catalyst and a preparation method thereof. The ortho-parahydrogen catalyst comprises the following components in percentage by weight: 70%-90% of amorphous hydrated iron oxide and 10%-30% of phenolic resin, the catalyst is spherical particles, the diameter of the catalyst is 0.3-1.0 mm, the crushing strength of the catalyst is 5-25 N / mm, and the abrasion of the catalyst is 0.02-0.10%. The preparation method of the ortho-parahydrogen catalyst comprises the following steps: fully mixing hydrated iron oxide powder, water-soluble phenolic resin and water, then carrying out extrusion molding on the mixture, molding the strip-shaped material into spherical particles by using a rounder, and drying to obtain the ortho-parahydrogen catalyst. The ortho-parahydrogen catalyst is spherical particles, and has the advantages of large specific surface area, high physical strength, low abrasion, convenience in filling, simple preparation method, low reaction temperature, low energy consumption, high preparation efficiency and high catalytic activity when being used for ortho-parahydrogen conversion.

Description

Technical Field

[0001] The invention belongs to the technical field of catalytic conversion of normal para-hydrogen and relates to a catalyst for conversion of normal para-hydrogen and a preparation method thereof. Background Art

[0002] With the increasing depletion of fossil energy and the emphasis of various countries on green environmental protection, the fossil fuel era is transforming into the green energy era, which is mainly reflected in the transformation of fossil energy consumption to green energy regeneration and the transformation of high-carbon fuels to low-carbon fuels. Hydrogen energy has attracted widespread attention due to its wide sources, combustibility, power generation, renewability, storage, zero emissions, and zero pollution. In the process of hydrogen energy utilization, storage and transportation are key technologies. Liquid hydrogen storage and transportation has the advantages of low cost, high hydrogen carrying density, high purity, suitability for long-distance transportation, and convenience for refueling in later applications. It is a key link in the widespread application of hydrogen energy.

[0003] Normally, hydrogen is a mixture of two hydrogen molecules, orthohydrogen and parahydrogen, and the equilibrium concentration between orthohydrogen and parahydrogen is only related to temperature. At room temperature and above, it is generally called normal hydrogen, which is composed of 75% orthohydrogen and 25% parahydrogen. At low temperatures, orthohydrogen will spontaneously convert to parahydrogen and release heat, causing the stored liquid hydrogen to vaporize. Even the evaporation of liquid hydrogen on the first day of storage can reach more than 20% of the total storage volume, and the loss will exceed 40% after 100 hours. Even if liquid normal hydrogen is stored in an ideal insulated container, liquid hydrogen will vaporize. Therefore, in the process of hydrogen liquefaction, multi-stage catalytic conversion of orthohydrogen and parahydrogen must be carried out to convert orthohydrogen into parahydrogen close to the equilibrium concentration, so that the parahydrogen content in the liquid hydrogen product reaches more than 95%, so as to reduce the evaporation loss of liquid hydrogen caused by the conversion of orthohydrogen and parahydrogen.

[0004] CN201910782910.2 discloses a method for preparing hydrated iron oxide, which uses a weak base as a precipitant, ferric chloride as a reactant, and disperses the product in an ammonium bicarbonate solution, filters, and dries to obtain hydrated iron oxide. This method uses the pore-forming effect of ammonium bicarbonate pyrolysis to cause a significant decrease in the strength of the dried particles. At the same time, the catalyst particles do not have a regular shape, have many edges and corners, and have high abrasion.

[0005] CN202111354244.6 discloses a method for preparing a doped ortho-parahydrogen conversion catalyst by a high-temperature hydrothermal method. The method drips a metal ion solution to be doped into an iron salt solution in a certain proportion, then adds an appropriate amount of alkali solution, obtains a precipitate through a hydrothermal reaction, and then obtains a hydrated iron oxide catalyst through washing, drying and grinding. The obtained catalyst particles do not have a regular shape, have low strength, and have large abrasion.

[0006] Particle strength and abrasion are important control indicators of catalytic materials. The hydrated iron oxide used in the above-mentioned para-hydrogen conversion catalyst has a low specific surface area, or has weak particle strength and high abrasion, which is not conducive to improving the performance of the para-hydrogen conversion catalyst. Summary of the invention

[0007] In view of the deficiencies of the prior art, the present invention provides a para-hydrogen catalyst and a preparation method thereof. The para-hydrogen catalyst of the present invention is a spherical particle, has a large specific surface area, high physical strength, low abrasion, convenient loading, a simple preparation method, a low reaction temperature, low energy consumption, high preparation efficiency, and high catalytic activity for para-hydrogen conversion.

[0008] The ortho-parahydrogen catalyst of the present invention comprises, based on the total weight of the catalyst, 70% to 90% of amorphous hydrated iron oxide and 10% to 30% of phenolic resin; the catalyst is spherical particles with a diameter of 0.3 to 1.0 mm, a crushing strength of 5 to 25 N / mm, and an abrasion of 0.02 to 0.10%.

[0009] The preparation method of the ortho-parahydrogen catalyst of the present invention comprises the following contents: fully mixing hydrated iron oxide powder, water-soluble phenolic resin and water, then extruding the mixture into strips, and then using a spheronizer to shape the strips into spherical particles, and drying to obtain the ortho-parahydrogen catalyst.

[0010] In the method of the present invention, the hydrated iron oxide powder is a commercial product or is prepared according to the prior art; the particle size of the hydrated iron oxide powder is 300-1000 meshes.

[0011] In the method of the present invention, the amount of water used should ensure that the viscous state of the water-soluble phenolic resin and the hydrated iron oxide powder after being fully mixed is suitable for extrusion molding using an extruder. There is no strict restriction on the order of adding the three, such as first dissolving the water-soluble phenolic resin powder in water and then mixing it with the hydrated iron oxide powder. The extrusion is a cylindrical strip, and the diameter of the strip is 0.2-1.0 mm, preferably 0.3-0.8 mm.

[0012] In the method of the present invention, the drying conditions are: drying temperature of 120-160° C., drying time of 6-36 hours, and drying is generally carried out in an air atmosphere.

[0013] The invention discloses an application of the para-hydrogen catalyst in the para-hydrogen conversion reaction, wherein the reaction conditions are as follows: the reaction temperature is 20 to 80 K, the volume space velocity is 200 to 2000 min -1 , preferably 400~1800min -1 .

[0014] Compared with the prior art, the present invention has the following advantages: (1) The present invention uses water-soluble phenolic resin as a binder, reacts with hydrated iron oxide powder, extrude and shape, rolls into spherical particles, and then continues to heat and solidify to form spherical catalyst particles. The present invention can achieve a higher hardness by curing under low temperature conditions, so that the catalyst has good strength and wear resistance; at the same time, it avoids the crystal transformation and specific surface area loss caused by high-temperature calcination of other binders (such as clay and other inorganic substances), resulting in a serious decrease in catalytic activity. The present invention also selects hydrated iron oxide powder with an appropriate mesh size to increase the external specific surface area of ​​the active component particles, which is beneficial to increase the effective contact area between hydrogen molecules and the catalyst.

[0015] (2) The present invention uses phenolic resin and extrude it into cylindrical strips less than 1 mm, and then forms the strips into spheres less than 1 mm by extrusion and spheronization. Phenolic resin plays a key role in forming ultra-small spherical particles due to its excellent viscosity and toughness. The present invention forms the catalyst particles into small spherical particles with a smooth surface and no obvious edges and corners. Moreover, due to the toughness of the phenolic resin after curing, it can further reduce wear compared with other special-shaped particles such as strips, and has the advantages of easy loading and not easy to break. DETAILED DESCRIPTION

[0016] The present invention is further described in detail below in conjunction with the examples. The crushing strength of the molded sample is tested according to the content of Chapter 5.11 of the HG / T 3927-2007 method; the determination method of the mass content of hydrated iron oxide is defined as follows: 5g of sample and 50mL of dilute hydrochloric acid with a mass fraction of 25% are placed in a 250mL conical flask, heated under reflux at 60°C for 1h, and then filtered to obtain the undissolved phenolic resin, dried and weighed, and the mass content of hydrated iron oxide is calculated. The parahydrogen content is calculated by gas chromatography. Example 1

[0017] The purchased amorphous hydrated iron oxide powder (specific surface area 205m 2 / g) is mixed with an appropriate amount of water-soluble phenolic resin, and an appropriate amount of water is added to make the mixture viscous enough to be extruded into cylindrical strips with a diameter of 0.5mm using an extruder. Then the strip particles are formed into spherical particles using a spheronizer. The spherical particles are then dried at 140℃ for 12 hours. Finally, spherical particles with a diameter of 0.6mm are obtained, and the crushing strength is 18.5N / mm. The hydrated iron oxide content is 88wt%, and the specific surface area is 190m 2 / g, and the attrition is 0.08%. The normal and para hydrogen conversion performance test is shown in Table 1. Example 2

[0018] The purchased amorphous hydrated iron oxide powder (specific surface area 205m 2 / g) is mixed with an appropriate amount of water-soluble phenolic resin, and an appropriate amount of water is added to make the mixture viscous enough to be extruded into cylindrical strips with a diameter of 0.4mm using an extruder. Then the strip particles are formed into spherical particles using a spheronizer. The spherical particles are then dried at 160℃ for 8 hours. Finally, spherical particles with a diameter of 0.5mm are obtained, and the crushing strength is 19.8N / mm. The hydrated iron oxide content is 85wt%, and the specific surface area is 185m 2 / g, and the attrition is 0.05%. The normal and para hydrogen conversion performance test is shown in Table 1. Example 3

[0019] The purchased amorphous hydrated iron oxide powder (specific surface area 205m 2 / g) is mixed with an appropriate amount of water-soluble phenolic resin, and an appropriate amount of water is added to make the mixture viscous enough to be extruded into cylindrical strips with a diameter of 0.7mm using an extruder. Then the strip particles are formed into spherical particles using a spheronizer. The spherical particles are then dried at 130°C for 16 hours. Finally, spherical particles with a diameter of 0.9mm are obtained, and the crushing strength is 16.7N / mm. The hydrated iron oxide content is 89wt%, and the specific surface area is 194m 2 / g, and the attrition is 0.10%. The normal and para hydrogen conversion performance test is shown in Table 1. Comparative Example 1

[0020] The preparation conditions are the same as those in Example 1, except that the particles are not formed into spherical particles.

[0021] The catalyst crushing strength was tested to be 17.4 N / mm and the abrasion loss was 0.16%. The normal and para hydrogen conversion performance test is shown in Table 1. Comparative Example 2

[0022] Iron oxide was prepared according to the method provided in Example 1 of CN202210029537.5. The iron oxide grain size was 23 nm and the crystallinity was high. After testing, its specific surface area was only 66 m 2 / g. It was pressed into 1mm thick tablets and slightly crushed. The normal and para hydrogen conversion performance test is shown in Table 1. Comparative Example 3

[0023] Hydrated iron oxide was prepared according to the method of Example 3 of CN201910782910.2. After testing, the obtained hydrated iron oxide was amorphous crystalline, the average particle size of hydrated iron oxide was 5.4 nm, and its specific surface area was 238 m 2 / g, the average particle strength is only 2.2N / mm, and the crushing strength is very low. The obtained particles are irregular in shape, and the abrasion loss is 0.39%. The normal and para hydrogen conversion performance test is shown in Table 1. Comparative Example 4

[0024] The preparation conditions were the same as in Example 1, except that the same weight of clay was added during the molding process.

[0025] The catalyst crushing strength was tested to be 10.1 N / mm and the abrasion loss was 0.28%. The normal and para hydrogen conversion performance test is shown in Table 1. Comparative Example 5

[0026] The preparation conditions were the same as those in Example 1, except that the same weight of clay was added during the molding process and the mixture was calcined at 500°C.

[0027] The catalyst was tested to have a crushing strength of 23.6 N / mm, abrasion of 0.19%, and a specific surface area of ​​78 m 2 / g normal and para hydrogen conversion performance test is shown in Table 1. Comparative Example 6

[0028] The preparation conditions were the same as those in Example 1, except that 5% phenolic resin was added during the molding process.

[0029] The catalyst was tested to have a crushing strength of 8.2 N / mm and abrasion of 0.30%. Due to the insufficient amount of phenolic resin, the hydrated iron oxide could not be fully bonded, resulting in poor abrasion and strength of the product.

[0030] Table 1 Parahydrogen conversion rate of catalysts Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Parahydrogen conversion rate % 98.6 98.4 98.8 98.0 84.7 96.0 98.4 83.2 Test conditions: Activation conditions: 130℃ vacuum drying for 12 hours, evaluation temperature 77K, volume space velocity 400min -1 .

Claims

1. A parahydrogen catalyst, characterized in that: The catalyst comprises, based on the total weight of the catalyst, 70% to 90% of amorphous hydrated iron oxide and 10% to 30% of phenolic resin.

2. The catalyst according to claim 1, characterized in that: The catalyst is spherical particles with a diameter of 0.3 to 1.0 mm.

3. The catalyst according to claim 1, characterized in that: The crushing strength is 5-25N / mm, and the abrasion is 0.02-0.10%.

4. A method for preparing a parahydrogen catalyst according to any one of claims 1 to 3, characterized in that The method comprises the following contents: fully mixing hydrated iron oxide powder, water-soluble phenolic resin and water, then extruding the mixture into strips, and then using a spheronizer to shape the strips into spherical particles, and drying to obtain a parahydrogen catalyst.

5. The method according to claim 4, characterized in that: The hydrated iron oxide powder is a commercial product or is prepared according to the prior art; the particle size of the hydrated iron oxide powder is 300-1000 meshes.

6. The method according to claim 4, characterized in that: The amount of water used should ensure that the viscous state of the water-soluble phenolic resin and the hydrated iron oxide powder after being fully mixed is suitable for extrusion molding.

7. The method according to claim 4, characterized in that: The water-soluble phenolic resin powder is first dissolved in water and then mixed with the hydrated iron oxide powder.

8. The method according to claim 4, characterized in that: The extrusion is into cylindrical strips, and the diameter of the strips is 0.2-1.0 mm, preferably 0.3-0.8 mm.

9. The method according to claim 2, characterized in that: The drying conditions are as follows: drying temperature of 120 to 160° C. and drying time of 6 to 36 hours.

10. Use of the para-hydrogen catalyst according to any one of claims 1 to 3 in a para-hydrogen conversion reaction, wherein the reaction conditions are: a reaction temperature of 20 to 80 K, a volume space velocity of 200 to 2000 min -1 , preferably 400~1800min -1 .