SU64607A1 - Method of making ammonia synthesis catalyst - Google Patents

Description

The catalyst currently used for the synthesis of acacia "a" is, in most cases, fused MgF: Fe: O4, with the addition of promoters (AljO-j, KjO). In the synthesis column, the catalyst is restored to hydrogen – hydrogen mixture at elevated temperature in the megallic iron, which, in fact, is the catalyst.

The implementation of the process of reducing the catalyst in the synthesis column leads to the formation of water in the system and, moreover, requires considerable time, which is associated with the loss of equipment productivity, since the catalyst is periodically replaced.

In the patent literature there are indications for the manufacture of a catalyst for ammonia synthesis by the reduction of metal oxides in special equipment.

However, pre-reduction of the catalyst in the usual way in a separate apparatus does not lead to the goal, since the reduced catalyst is pyrophoric, i.

is heated and irreversibly loses catalytic activity.

The authors found that if the usual catalyst for ammonia synthesis is restored, cooled in a nitrogen-hydrogen mixture and then treated in the cold for some time with a nitrogen-hydrogen mixture containing a small amount of oxygen (for example, 0.1-0.2% by volume), then passivation occurs. metal surface. The introduction of oxygen into the mixture is most easily accomplished by adding to it the appropriate amount of air. After this treatment, the catalyst becomes non-pyrophoric — it does not heat up under the action of air. Being loaded into the apparatus for ammonia synthesis, the catalyst under the action of the nitrogen-hydrogen mixture at the usual synthesis temperature is quickly released from the passivation film and, as shown by experiments, gives an activity equal to the activity of the catalyst recovered directly in the synthesis apparatus.

The described method of passivation of the catalyst can be applied

also in cases when there is a need for repair for changing the internal packing of the synthesis column, while the catalyst is still active and does not require a change. To date, in such cases, the catalyst has been lost. When the passivation is carried out by the described method, a catalyst can be used again before the air is introduced into the column.

Subject invention

A method for producing a catalyst for ammonia synthesis by reducing a mixture of metal oxides from a whole synthesis column, characterized in that, in order to eliminate the pyrophoric properties of the catalyst, the reduced product is treated with a gas mixture containing a small amount of oxygen.