When Mr. Haber was creating Ammonia, he had a big problem. He couldn't get his catalyst which worked on adsorption to work efficiently. He had to use too many expensive iron blocks.
One day his student replaced them with fine iron powder. It worked miraculously better.
What made the difference?
We have seen how adsorption is affected by surface area of the adsorbent. More the surface area of the adsorbent, more area is available for adsorption and hence, higher will be the adsorption.
As a general rule, more surface area means more adsorption.
In this case, the iron in the powder form has a much much higher surface area than iron in block form. This increased the efficiency of the catalyst to a very high extent and gave Mr. Haber his ammonia in a better way.