A catalytic element for the conversion of ammonia

 

(57) Abstract:

The invention relates to a device for catalytic elements used in the manufacture of nitric acid by the contact method and other processes where there is a stage catalytic conversion of ammonia. Describes a catalytic element for the conversion of ammonia in the form of a package platinum mesh elements with dividing strips of non-metallic materials, the separator strip modified active phase based on platinum or palladium, or chromium oxide, or cobalt oxide, the content of the active phase is 0.0001 to 0.01% by weight of the dividing strip. The technical result is the acceleration output of the catalytic element in the optimal mode for 1-1 .5 hours while maintaining the discharge coefficient of the platinum level by 0.055-0,065 g/T. table 1.

The invention relates to a device for catalytic elements used in the manufacture of nitric acid by the contact method and other processes where there is a stage catalytic conversion of ammonia.

Known catalytic element consisting of platinum, the first layer, the palladium - the second layer, the third layer consists of platinum or refractory material is efficiency due to the long time optimal (over 2 days) high loss factor platinum.

Also known catalyst for the conversion of ammonia, in which the proposed structure of the catalytic package using pre-separation pads, containing not less than 0.01 wt.% the active metal on the carrier is silica and/or alumina in the form of woven and nonwoven fibrous materials (patent RF N 2069584, class B 01 J 23/38, 1996).

The disadvantage of this catalyst for the conversion of ammonia is the need for a long period of its operation to output optimum mode associated with activation of the catalytic surface of the package.

The closest in technical essence is a catalytic element for the conversion of ammonia in the form of a package platinum mesh elements with dividing strips of non-metallic materials (patent RF N 2069585, class B 01 J 23/42, 1996, prototype)

The disadvantage of this element is the need for the same duration of time (about 2 days) to exit the catalytic element in the optimal mode.

The present invention is to accelerate the exit of the catalytic element in the optimal mode for 1-1 .5 hours while maintaining consumable coustom catalytic element for the conversion of ammonia in the form of a package platinum mesh elements with dividing strips of non-metallic materials of the barrier strip modified active phase based on platinum or palladium, or chromium oxide, or cobalt oxide, the content of the active phase is 0.0001 - 0.01% of the mass of the dividing strip.

The technical result from the use of the invention is achieved due to the fact that the active dividing strip, especially at the initial stage of inclusion catalyst package in the conversion process, reduce the period of optimal (from the point of view of conversion) of the whole catalyst package. Simultaneously activated dividing strip keep performing their core functions antipollution protect the platinum catalyst grids, which allow to reduce losses of platinum, playing the role of a damper (shock absorber).

Example 1 (prototype)

Catalyst package for unit AK-72 is formed of six nets (mesh diameter 3800 mm) platinum-rhodium-palladium alloy, each of which layers is divided silica grids with the size of the free cell 10 mm

Measurement conversion is performed after the ignition of the catalyst grids, respectively, after 2 hours, 10 hours and 24 hours.

The measurement results are shown in table.

Standard conversion (95,5%) to the earth dividing strips contain catalytically active phase - platinum in an amount of 0.01 wt.%.

Patinirovanie is carried out by impregnation of the silica-grid solution of hexachloroplatinic acid of appropriate concentration, drying mesh and subsequent decomposition of H2PtCl66H2O when heat-treated nets.

The measurement results after the start of the unit are summarized in table.

Standard conversion (95,5%) is achieved after 24 hours after the start of the unit (after ignition of the platinum mesh).

For comparison: 1 day unit AK-72 when the conversion is 5% below the regular leads to lower commodity production of nitric acid at 50 so

Example 3

Analogously to example 2, but silica separation pads contain catalytically active phase - platinum in the amount of 0.001 wt.%.

The measurement results after the start of the unit with the specified package platinum meshes are summarized in table.

Standard conversion (95,5%) is achieved after 27 hours.

Example 4

Similar to example 3, but silica separation pads contain catalytically active phase - platinum in the amount of 0.0001 wt.%.

The measurement results after the start of the unit are summarized in table.

silica separation pads contain catalytically active phase - palladium in the amount of 0.0001 wt.%.

The deposition of palladium on a silica separation strip was carried out by soaking them in a solution of the appropriate concentration of palladium chloride with subsequent thermal decomposition of the specified salt.

The results of measure conversion after starting the unit with the specified package platinum meshes are summarized in table.

Standard conversion (95,5%) is achieved after 29 hours after the start of the unit.

Example 6

Analogous to example 5, but silica separation pads contain catalytically active phase - palladium in an amount of 0.01 wt.%.

The measurement results of the conversion are summarized in table.

Standard conversion (95,5%) is achieved after 26 hours.

Example 7

Similar to example 6, but silica separation pads contain catalytically active phase - chromium oxide in an amount of 0.0001 wt.%.

The application of chromium oxide on silica dividing strip was carried out by soaking them in a solution of the appropriate concentration of chromium acetate, followed by thermal decomposition of the specified salt.

The measurement results of the conversion are summarized in tabliture silica separation pads contain catalytically active phase - chromium oxide in an amount of 0.01 wt.%.

The measurement results of the conversion are summarized in table.

Standard conversion (95,5%) is achieved after 32 hours.

Example 9

Same as example 8, but silica separation pads contain a catalytically active oxide of cobalt (CO2O3) - in the amount of 0.0001 wt.%.

Deposition of cobalt oxide on silica dividing strip was carried out by soaking them in a solution of the appropriate concentration of cobalt nitrate with subsequent thermal decomposition of the specified salt.

The measurement results of the conversion are summarized in table.

Standard conversion (95,5%) is achieved after 34 hours.

Example 10

Similar to example 9, but silica separation pads contain catalytically active phase - cobalt oxide in an amount of 0.01 wt.%.

The measurement results of the conversion are summarized in table.

Standard conversion (95,5%) is achieved after 32 hours.

Thus, the technical result from the use of the invention is expressed in accelerating the exit of the catalytic element in the optimal mode to 1.0-1.5 days. This is because dividing steget maximum level, while the expenditure ratio of platinum remains at the level of 0,055 - 0,065 g/T.

A catalytic element for the conversion of ammonia in the form of a package platinum mesh elements with dividing strips of non-metallic materials, characterized in that the separating strip modified active phase based on platinum or palladium, or chromium oxide, or cobalt oxide, the content of the active phase is 0.0001 to 0.01% by weight of the dividing strip.

 

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