{HEAD ~ Preferred catalyst} comprises {TAIL ~ potassium antimonate} together with potassium sulfate and minor amounts of zinc sulfate and cupric sulfate  
comprises
{ HEAD ~ Preferred catalyst } comprises { TAIL ~ potassium antimonate } together with potassium sulfate and minor amounts of zinc sulfate and cupric sulfate
HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH