Ruthenium ammonia synthesis catalyst with high-specific-surface-area graphite as carrier and preparation of ruthenium ammonia synthesis catalyst

Abstract

The invention discloses a ruthenium ammonia synthesis catalyst with high-specific-surface-area graphite as a carrier and a preparation of the ruthenium ammonia synthesis catalyst. The ruthenium ammonia synthesis catalyst comprises Ru-Ba / HAG, wherein Ru refers to an active ingredient ruthenium accounting for 1-8% of the mass of the carrier; Ba refers to assistant barium accounting for 1-10% of the mass of the carrier; HAG refers to the graphite with a high specific surface area. With the high-specific-surface-area graphite as the carrier, the ammonia synthesis catalyst is prepared by preparing potassium ruthenate, supporting the catalyst, pressing and forming. The high-specific-surface-area graphite has relatively large specific surface area and porous volume and can provide enough space for metal dispersion; the surface energy is singular to provide the precondition for obtaining uniform metallic particles; the activity of the catalyst taking the high-specific-surface-area graphite as the carrier is higher than that of the catalyst taking ordinary graphite as the carrier; the surface functional groups of the graphite can be adjusted through different atmospheres, so as to obtain high-specific-surface-area graphite with different kinds and different quantity of surface functional groups; the high-specific-surface-area graphite has different characteristics when being used as the carrier of the ruthenium ammonia synthesis catalyst.

Description

technical field

[0001] The invention belongs to the technical field of ammonia synthesis catalyst preparation, and more specifically relates to a ruthenium-based ammonia synthesis catalyst with high specific surface graphite as a carrier and a preparation method thereof. Background technique

[0002] In the field of ammonia synthesis catalysts, activated carbon or graphitized activated carbon as a carrier has the highest ruthenium-based ammonia synthesis activity, but in the presence of ruthenium, carbon can undergo a methanation reaction with hydrogen, one of the reactants for ammonia synthesis, resulting in the loss of the carrier. The catalyst structure collapses. The industrialization process of carbon-supported catalysts is restricted by the stability of carbon supports, so it is still difficult to widely promote carbon-supported ruthenium-based ammonia synthesis catalysts. In laboratory research, graphitized activated carbon has better stability and activity, so choos...

Examples

Embodiment 1

[0022] (1) Weigh graphite with a mass of 4.00 g and a magnetic steel needle with a mass of 20.00 g (the size of the magnetic steel needle is 1mm) and place them in a closed 400mL glass container filled with air; use a water bath to control the temperature at 40°C , run continuously at 1800 r / min for different t times, then add 20mL of deionized water and continue to rotate for 2h, then sedimentation, filtration, separation and drying to obtain high specific surface graphite solid powder; high specific surface graphite physical texture prepared by different magnetic grinding time The structure is shown in Table 1 below;

[0023] Table 1 Physical texture of high specific surface graphite obtained under different magnetic grinding times

[0024]

[0025] (2) Preparation of potassium ruthenate: put ruthenium powder and potassium hydroxide in a nickel crucible and mix evenly, and treat in a muffle furnace at 400°C for 4 hours to obtain potassium ruthenate;

[0026] (3) Catalyst...

Embodiment 2

[0029] Change the graphite mass m and replace the magnetic grinding container with a 200mL glass container. The magnetic grinding time is 12h, and other conditions are the same. The physical texture of graphite with large specific surface area prepared by the same steps is shown in Table 2;

[0030] Table 2 Physical texture of large specific surface graphite prepared with different ball-to-material ratios

[0031]

[0032] (2) Preparation of potassium ruthenate: put ruthenium powder and potassium hydroxide in a nickel crucible and mix them evenly, and treat them in a muffle furnace at 650°C for 1 hour to obtain potassium ruthenate. The content of ruthenium is 4% of the mass of the carrier;

[0033] (3) Catalyst preparation: Immerse the high specific surface graphite carrier HAG-5 obtained in step (1) in the solution of potassium ruthenate obtained in step (2) by equal-volume impregnation method, and control the temperature at 60°C. The impregnation time is 3 minutes; the im...

Embodiment 3

[0036] Take the ordinary graphite in Example 2 as the carrier, the content of ruthenium is 4% of the carrier mass, the amount of additive Ba is 2% of the carrier mass, the hydrogen-nitrogen ratio in the mixed gas is 3:1, and the space velocity is 10000 h -1 , the tableting pressure is 10 MPa, and the reaction temperature is 400 ℃, the optimum activity of ruthenium-based ammonia synthesis catalyst is 2.3%.

technical field

[0001] The invention belongs to the technical field of ammonia synthesis catalyst preparation, and more specifically relates to a ruthenium-based ammonia synthesis catalyst with high specific surface graphite as a carrier and a preparation method thereof. Background technique

[0002] In the field of ammonia synthesis catalysts, activated carbon or graphitized activated carbon as a carrier has the highest ruthenium-based ammonia synthesis activity, but in the presence of ruthenium, carbon can undergo a methanation reaction with hydrogen, one of the reactants for ammonia synthesis, resulting in the loss of the carrier. The catalyst structure collapses. The industrialization process of carbon-supported catalysts is restricted by the stability of carbon supports, so it is still difficult to widely promote carbon-supported ruthenium-based ammonia synthesis catalysts. In laboratory research, graphitized activated carbon has better stability and activity, so choos...

Examples

Embodiment 1

[0022] (1) Weigh graphite with a mass of 4.00 g and a magnetic steel needle with a mass of 20.00 g (the size of the magnetic steel needle is 1mm) and place them in a closed 400mL glass container filled with air; use a water bath to control the temperature at 40°C , run continuously at 1800 r / min for different t times, then add 20mL of deionized water and continue to rotate for 2h, then sedimentation, filtration, separation and drying to obtain high specific surface graphite solid powder; high specific surface graphite physical texture prepared by different magnetic grinding time The structure is shown in Table 1 below;

[0023] Table 1 Physical texture of high specific surface graphite obtained under different magnetic grinding times

[0024]

[0025] (2) Preparation of potassium ruthenate: put ruthenium powder and potassium hydroxide in a nickel crucible and mix evenly, and treat in a muffle furnace at 400°C for 4 hours to obtain potassium ruthenate;

[0026] (3) Catalyst...

Embodiment 2

[0029] Change the graphite mass m and replace the magnetic grinding container with a 200mL glass container. The magnetic grinding time is 12h, and other conditions are the same. The physical texture of graphite with large specific surface area prepared by the same steps is shown in Table 2;

[0030] Table 2 Physical texture of large specific surface graphite prepared with different ball-to-material ratios

[0031]

[0032] (2) Preparation of potassium ruthenate: put ruthenium powder and potassium hydroxide in a nickel crucible and mix them evenly, and treat them in a muffle furnace at 650°C for 1 hour to obtain potassium ruthenate. The content of ruthenium is 4% of the mass of the carrier;

[0033] (3) Catalyst preparation: Immerse the high specific surface graphite carrier HAG-5 obtained in step (1) in the solution of potassium ruthenate obtained in step (2) by equal-volume impregnation method, and control the temperature at 60°C. The impregnation time is 3 minutes; the im...

Embodiment 3

[0036] Take the ordinary graphite in Example 2 as the carrier, the content of ruthenium is 4% of the carrier mass, the amount of additive Ba is 2% of the carrier mass, the hydrogen-nitrogen ratio in the mixed gas is 3:1, and the space velocity is 10000 h -1 , the tableting pressure is 10 MPa, and the reaction temperature is 400 ℃, the optimum activity of ruthenium-based ammonia synthesis catalyst is 2.3%.

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