{TAIL ~ O3 catalyst comprising} of a mixture of from 2.5 to 7.5% {HEAD ~ wt} of Cr2 O3, 5 to 17.5% wt of Al2 O3 and 75 to 85% wt of a Zn ZSM 5 zeolite or a Zn ZSM 5 zeolite/asbestos 
{ TAIL ~ O3 catalyst comprising } of a mixture of from 2.5 to 7.5 % { HEAD ~ wt } of Cr2 O3 , 5 to 17.5 % wt of Al2 O3 and 75 to 85 % wt of a Zn ZSM 5 zeolite or a Zn ZSM 5 zeolite / asbestos
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH