Catalytic poison in Pt catalysed manufacture of H2SO4 I came across a question that goes as:


  In manufacturing of sulfuric acid in presence of platinum catalyst, which metal impurity acts as a catalytic poison?
  
  
  Fe
  Cr
  Cu
  V
  


I searched everywhere I could but did not find anything that talks about this.
I read about $\ce{As2O3}$ being a catalytic poison in this reaction and recommendations for using the Contact process using $\ce{V2O5}$ instead of this reaction.

I can understand that this is more of a fact based question but reasons or explanation (if any) should please be included.
$\ce{Fe}$ and $\ce{V}$ are used in the contact process.
$\ce{Cu}$ is used in the preparation of chlorine gas.
Thus $\ce{Cr}$ can be used as a catalyst poison.