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