Why is the alkaline pyrogallol added to the air in the gas syringe?

The alkaline pyrogallol removes oxygen and carbon dioxide from the air so that the gas remaining is largely nitrogen.

How is the catalyst used in this demonstration similar to and different from the catalyst used in the industrial process?

The catalyst is similar in that it is mainly made of iron but the industrial catalyst also contains promotors such as potassium oxide or aluminium oxide.

How can you tell that ammonia has been produced?

The red Universal Indicator solution is turned blue by the alkaline ammonia.

In what other way is the industrial process different from the laboratory demonstration?

The industrial process is carried out at between 50 and 100 atmospheres but the demonstration is carried out at atmospheric pressure. The yield of ammonia is therefore likely to be much lower that that achieved in industry.