What is a pre-reduced ammonia synthesis catalyst? What are the advantages and disadvantages?

The pre-reduced catalyst has been reduced before leaving the factory; it only has an iron oxide film on its surface, and the amount of oxygen it can absorb is only 2% of its total weight. Its advantages are: 1. Complete reduction and high activity; 2. Low bulk density, which saves space in the synthesis tower. 3. Short reduction time, which reduces the startup time of the factory. 4. It can overcome the disadvantage of poor reduction conditions. Its disadvantages are: low strength, high cost, and high requirements for storage and transportation.

A pre-reduced catalyst is one in which the iron catalyst has been largely reduced during manufacturing; there is only an oxide layer on the surface of the catalyst particles, which serves to protect it. Advantages: During reduction, it has a low activation temperature and produces less water. Reduction time is shortened. Disadvantage: Since the catalyst is already active, it will undergo oxidation reactions when exposed to oxygen in the air over a long period of time, which makes it difficult to transport and store.

A pre-reduction catalyst means that the catalyst manufacturer has a catalytic reduction device; after the catalyst is produced, it is directly reduced in this reduction device. The manufacturer who uses the catalyst then places it in a tower, raises the temperature, and carries out a simple reduction process to enable operation at light load. Its advantages include reducing the heating and reduction time required per unit of catalyst used, thereby increasing the effective production time (especially during the peak season for fertilizer sales). Additionally, by using pre-reduced catalysts, it is possible to minimize the issues that arise when reducing old and new catalysts, without the need to replace the entire catalyst in the tower ； The downside is that the transportation and loading of pre-reduced catalysts are very troublesome; if the sealing measures are not proper, it can lead to catalyst oxidation.

Generally, pre-reduction is installed in the upper section of the first bed in the synthesis tower; this makes it easier to carry out reduction during startup, facilitates reaching the active temperature, and allows heat to be transferred to the lower bed once the reaction begins, thereby accelerating the reduction process.

A pre-reduced catalyst is one in which the iron catalyst has been largely reduced during manufacturing; there is only an oxide layer on the surface of the catalyst particles, which serves to protect it. Advantages: During reduction, it has a low activation temperature and produces less water. Reduction time is shortened. Disadvantage: Since the catalyst is already active, it will undergo oxidation reactions when exposed to oxygen in the air over a long period of time, which makes it difficult to transport and store.