Ortho-para hydrogen catalyst and method of making same

Abstract

The application discloses a primary and secondary hydrogen catalyst and a preparation method thereof. The primary and secondary hydrogen catalyst comprises 70-90% of amorphous hydrated iron oxide and 10-30% of phenolic resin in terms of the total weight of the catalyst. The catalyst is spherical particle with a diameter of 0.3-1.0 mm and a crushing strength of 5-25 N / mm, and the attrition is 0.02-0.10%. The preparation method of the primary and secondary hydrogen catalyst comprises the following steps: mixing hydrated iron oxide powder, water-soluble phenolic resin and water sufficiently, then extruding the mixture into a strip shape, using a rolling machine to shape the strip-shaped material into spherical particles, and drying to obtain the primary and secondary hydrogen catalyst. The primary and secondary hydrogen catalyst is spherical particle with a large specific surface area, high physical strength, small attrition, and is convenient to load. The preparation method is simple, the reaction temperature is low, the energy consumption is small, the preparation efficiency is high, and the primary and secondary hydrogen conversion catalytic activity is high.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of ortho-para hydrogen catalytic conversion, and relates to an ortho-para hydrogen conversion catalyst and a preparation method thereof. BACKGROUND

[0002] With the increasing depletion of fossil energy and the emphasis on green environmental protection by various countries, the fossil fuel era is changing to a green energy era, mainly reflected in the change from fossil energy consumption to green energy regeneration and the change from high-carbon fuel to low-carbon fuel. Hydrogen energy has attracted widespread attention due to its characteristics of wide sources, flammability, power generation, renewability, storability, zero emission and zero pollution. In the utilization process of hydrogen energy, storage and transportation are key technologies. Liquid hydrogen storage and transportation has the advantages of low cost, large hydrogen carrying density, high purity, suitability for long-distance transportation and convenience for later application, and is a key link for the widespread application of hydrogen energy.

[0003] Generally, hydrogen is a mixture of ortho-hydrogen and para-hydrogen, and the equilibrium concentration between ortho-hydrogen and para-hydrogen is only related to temperature. At room temperature and above, it is generally called normal hydrogen, which is composed of 75% ortho-hydrogen and 25% para-hydrogen. At low temperatures, ortho-hydrogen will spontaneously convert to para-hydrogen and release heat, causing the vaporization of stored liquid hydrogen. Even the evaporation amount of liquid hydrogen in the first day of storage can reach more than 20% of the total storage amount, and the loss after 100 h will exceed 40%. Even if the liquid normal hydrogen is stored in an ideal adiabatic container, the liquid hydrogen will also vaporize. Therefore, in the hydrogen liquefaction process, multi-stage ortho-para hydrogen catalytic conversion must be carried out to convert ortho-hydrogen to para-hydrogen close to the equilibrium concentration, so that the para-hydrogen content in the liquid hydrogen product reaches more than 95%, thereby reducing the loss of liquid hydrogen evaporation caused by ortho-para hydrogen conversion.

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

[0005] CN202111354244.6 discloses a method for preparing a doped ortho-para hydrogen conversion catalyst by high-temperature hydrothermal method. The method drops a metal ion solution to be doped into an iron salt solution in a certain proportion, then adds an appropriate amount of lye, and obtains a precipitate through hydrothermal reaction, and then the precipitate is washed, dried and ground to obtain a hydrated iron oxide catalyst. The obtained catalyst particles do not have a regular shape and have low strength, resulting in high abrasion.

[0006] Particle strength and abrasion are important control indicators of catalytic materials. The specific surface area of the hydrated iron oxide used in the conversion of primary and secondary hydrogen is low, or the particle strength is weak and the abrasion is high, which is not conducive to improving the performance of the primary and secondary hydrogen conversion catalyst. SUMMARY

[0007] In view of the deficiencies of the prior art, the present application provides a primary and secondary hydrogen catalyst and a preparation method thereof. The primary and secondary hydrogen catalyst of the present application is spherical particles with large specific surface area, high physical strength, small abrasion, easy to load, simple preparation method, low reaction temperature, small energy consumption, high preparation efficiency and high primary and secondary hydrogen conversion catalytic activity.

[0008] The primary and secondary hydrogen catalyst of the present application comprises, based on the total weight of the catalyst: 70% to 90% amorphous hydrated iron oxide and 10% to 30% 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 primary and secondary hydrogen catalyst of the present application comprises the following steps: mixing hydrated iron oxide powder, water-soluble phenolic resin and water thoroughly, then extruding the mixture into strips, using a rounding machine to shape the strip-shaped material into spherical particles, and drying to obtain the primary and secondary hydrogen catalyst.

[0010] In the method of the present application, the hydrated iron oxide powder is a commercially available product or is prepared according to the prior art; the particle size of the hydrated iron oxide powder is 300 to 1000 mesh.

[0011] In the method of the present application, the amount of water used should ensure that the viscous state of the mixture of water-soluble phenolic resin and hydrated iron oxide powder after thorough mixing is suitable for extrusion molding using an extruder. The order of addition of the three is not strictly limited, for example, the water-soluble phenolic resin powder can be dissolved in water first, and then mixed with the hydrated iron oxide powder. The extrusion is cylindrical strips, and the diameter of the strip-shaped material is 0.2 to 1.0 mm, preferably 0.3 to 0.8 mm.

[0012] In the method of the present application, the drying conditions are: drying temperature 120 to 160℃, drying time 6 to 36 hours, and drying is generally carried out in air atmosphere.

[0013] The application of the primary and secondary hydrogen catalyst of the present application in the conversion of primary and secondary hydrogen has the following reaction conditions: reaction temperature 20 to 80K, and volume space velocity 200 to 2000min -1 , preferably 400 to 1800min -1 .

[0014] Compared with the prior art, the present application has the following advantages:

[0015] (1) The present application uses water-soluble phenolic resin as a binder, which is reacted with hydrated iron oxide powder, extruded, and formed into spherical particles by rolling. The present application can achieve high hardness at low temperature, so that the catalyst has good strength and wear resistance. At the same time, the crystal transformation and specific surface area loss caused by high-temperature calcination of other binders (such as inorganic substances such as clay) are avoided, which leads to a serious decrease in catalytic activity. The present application also selects hydrated iron oxide powder with appropriate mesh size, which can increase the external specific surface area of the active component particles, and is beneficial to increase the effective contact area of hydrogen molecules and the catalyst.

[0016] (2) The present application uses phenolic resin, which is extruded into cylindrical strips less than 1 mm, and then the strips are formed into spherical particles less than 1 mm by the method of extrusion and rolling. Phenolic resin plays a key role in the formation of ultra-small particle spherical particles due to its excellent toughness. The catalyst particles are formed into small spherical particles in the present application, and the surface of the spherical particles is smooth without obvious corners. Due to the toughness of the phenolic resin after curing, compared with other irregular particles such as strips, the wear can be further reduced, and the catalyst has the advantages of easy loading and not easy to break. DETAILED DESCRIPTION

[0017] The present application will be further described in detail below with reference to examples. The crushing strength of the formed sample is detected according to the method in chapter 5.11 of HG / T 3927-2007; the determination method of the mass content of hydrated iron oxide is defined as follows: 5 g of sample and 50 mL of 25% dilute hydrochloric acid are placed in a 250 mL conical flask, heated and refluxed at 60°C for 1 h, then filtered to obtain the undissolved phenolic resin, which is dried and weighed to calculate the mass content of hydrated iron oxide. The content of para-hydrogen is calculated by gas chromatography. Example 1

[0018] The purchased amorphous hydrated iron oxide powder (specific surface area 205 m 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 and suitable for extruding cylindrical strips with a diameter of 0.5 mm by using an extruder. Then the strip particles are formed into spherical particles by using a rolling machine. The spherical particles are dried at 140°C for 12 hours. Finally, spherical particles with a diameter of 0.6 mm are obtained, with a crushing strength of 18.5 N / mm. The hydrated iron oxide content is 88 wt%, the specific surface area is 190 m 2 / g, and the wear is 0.08%. The para-hydrogen conversion performance test is shown in Table 1. Example 2

[0019] The purchased amorphous hydrated iron oxide powder (specific surface area 205 m 2 / g) was mixed with a proper amount of water-soluble phenolic resin, and a proper amount of water was added to make the mixture have a suitable sticky state for extruding cylindrical strips with a diameter of 0.4 mm using an extruder. Then, a roller was used to shape the strip-shaped particles into spherical particles. The spherical particles were dried at 160°C for 8 hours. Finally, spherical particles with a diameter of 0.5 mm were obtained, and the crushing strength was 19.8 N / mm. The hydrated iron oxide content was 85 wt%, the specific surface area was 185 m 2 / g, and the abrasion was 0.05%. The ortho-para hydrogen conversion performance test is shown in Table 1. Example 3

[0020] A purchased amorphous hydrated iron oxide powder (specific surface area 205 m 2 / g) was mixed with a proper amount of water-soluble phenolic resin, and a proper amount of water was added to make the mixture have a suitable sticky state for extruding cylindrical strips with a diameter of 0.7 mm using an extruder. Then, a roller was used to shape the strip-shaped particles into spherical particles. The spherical particles were dried at 130°C for 16 hours. Finally, spherical particles with a diameter of 0.9 mm were obtained, and the crushing strength was 16.7 N / mm. The hydrated iron oxide content was 89 wt%, the specific surface area was 194 m 2 / g, and the abrasion was 0.10%. The ortho-para hydrogen conversion performance test is shown in Table 1. Comparative Example 1

[0021] The preparation conditions were the same as in Example 1, except that the spherical particles were not shaped.

[0022] The catalyst crushing strength was 17.4 N / mm, and the abrasion was 0.16% after testing. The ortho-para hydrogen conversion performance test is shown in Table 1. Comparative Example 2

[0023] Iron oxide was prepared according to the method provided in Example 1 of CN202210029537.5, the iron oxide crystal grain size was 23 nm, the crystallinity was high, and the specific surface area was only 66 m 2 / g after testing. It was pressed into a 1 mm thick sheet, and then slightly crushed. The ortho-para hydrogen conversion performance test is shown in Table 1. Comparative Example 3

[0024] Hydrated iron oxide was prepared according to the method of Example 3 of CN201910782910.2. The obtained hydrated iron oxide was amorphous, the average particle size of the hydrated iron oxide was 5.4 nm, the specific surface area was 238 m 2 / g, and the average strength of the particles was only 2.2 N / mm, the crushing strength was very low. The obtained particles were irregular in shape, and the abrasion was 0.39%. The ortho-para hydrogen conversion performance test is shown in Table 1. Comparative Example 4

[0025] The preparation conditions are the same as in Example 1, except that the same weight of clay is added during the molding process.

[0026] The catalyst crushing strength is 10.1 N / mm, and the attrition is 0.28% after testing. The normal-parahydrogen conversion performance test is shown in Table 1. Comparative Example 5

[0027] The preparation conditions are the same as in Example 1, except that the same weight of clay is added during the molding process, and the catalyst is calcined at 500°C.

[0028] The catalyst crushing strength is 23.6 N / mm, the attrition is 0.19%, and the specific surface area is 78 m 2 / g after testing. The normal-parahydrogen conversion performance test is shown in Table 1. Comparative Example 6

[0029] The preparation conditions are the same as in Example 1, except that 5% of phenolic resin is added during the molding process.

[0030] The catalyst crushing strength is 8.2 N / mm, and the attrition is 0.30% after testing. Because the amount of phenolic resin is too small, the hydrated iron oxide cannot be fully bonded, resulting in poor product attrition and strength.

[0031] Table 1 Parahydrogen Conversion of Catalyst

[0032] Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 % Secondary hydrogen conversion 98.6 98.4 98.8 98.0 84.7 96.0 98.4 83.2

[0033] Test conditions: The activation condition is vacuum drying at 130°C for 12 hours, the evaluation temperature is 77K, and the volume space velocity is 400 min -1 .

Claims

1. A secondary hydrogen catalyst, characterized in that: The catalyst comprises, by total weight, 70%–90% hydrated iron oxide powder and 10%–30% water-soluble phenolic resin; the preparation method of the secondary hydrogen catalyst includes the following steps: thoroughly mixing hydrated iron oxide powder, water-soluble phenolic resin and water, then extruding the mixture into strips, then using a spherical rolling mill to shape the strip material into spherical particles, and drying to obtain the secondary hydrogen catalyst.

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

3. The catalyst according to claim 1, characterized in that: The catalyst has a crushing strength of 5–25 N / mm and an abrasion rate of 0.02–0.10%.

4. A method for preparing the secondary hydrogen catalyst according to any one of claims 1 to 3, characterized in that... The process includes the following steps: thoroughly mixing hydrated iron oxide powder, water-soluble phenolic resin, and water; then extruding the mixture into strips; using a spherical rolling mill to shape the strip material into spherical particles; and finally drying to obtain a neutral hydrogen catalyst.

5. The method according to claim 4, characterized in that: The hydrated iron oxide powder is a commercially available product; the particle size of the hydrated iron oxide powder is 300-1000 mesh.

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

7. The method according to claim 4, characterized in that: First, dissolve the water-soluble phenolic resin in water, and then mix it with hydrated iron oxide powder.

8. The method according to claim 4, characterized in that: The material is extruded into cylindrical strips with a diameter of 0.2–1.0 mm.

9. The method according to claim 4, characterized in that: The drying conditions are: drying temperature 120-160℃, drying time 6-36 hours.

10. The application of the n-secondary hydrogen catalyst according to any one of claims 1 to 3 in the n-secondary hydrogen conversion reaction, wherein the n-secondary hydrogen conversion reaction conditions are: reaction temperature 20-80 K, volume hourly space velocity 200-2000 min⁻¹. -1 .