Why are we keen to convert the catalyst to sulfied form?

on is a transition element. In nature  iron exists in the form of ore (iron oxide)  and it has four allotropic forms. Pure iron melts on Degree Centigrade, On cooling it goes in to different crystalline structure i.e. Delta, Gamma and Alfa ( BCC, FCC, BCC).  The percentage of Carbon makes the Iron, Steel and Cast Iron. If the percentage of carbon is up to2% it is called Steel while in cast iron the %C remains from2 -6.7%. Steel has  also classifications as well as cast iron too.