Is there a positive or a negative promoter which is added to the catalyst ?
Promoter is something added to the catalyst to enhance the catalytic action.
A catalyst is a substance that increases the rate of a chemical reaction without itself being changed at the end of the chemical reaction. Catalysts participate in reactions but are neither reactants nor products of the reaction Promoter is a material that enhances the action of a catalyst without actually having any catalytic value itself. For example in Haber's process, iron act as a catalyst. And molybdenum is added into it, which increases the efficiency of iron, hence acts as promoter.
So there are positive and negative promoters added to the catalyst