Refinery profitability can be maximised by selectively choosing the proper ZSM-5 type additive. When propylene demand is high, Johnson Matthey’s INTERCAT ZSM-5 based additives, PENTACAT HP, PROPYL MAX, SUPER Z, SUPER Z EXCEL, and SUPER Z EXCEED, are highly selective for cracking low octane gasoline range molecules to C3 and C4 olefins with no increase in coke or C2 and lighter gases. ZSM-5 isomerizes straight chain C4–C10 molecules to more highly branched molecules. The cracking of low octane components out of the gasoline, together with isomerization, result in increased gasoline octane (RON and MON). In addition, the isobutane yield also increases via secondary hydrogen transfer of some of the isobutene formed on ZSM-5 on the RE-USY in the base catalyst. Isobutane and n-C4 olefins are valuable as feeds for alkylation units, isobutene is valuable as feed to etherification units such as ETBE.
When butylene production is the primary goal, our INTERCAT ZMX additive, ZMX-BHP, allows the refiner to increase FCC gasoline octane and LPG yields, but primarily at the expense of LCO instead of gasoline. The ZMX family of additives also significantly increases the C4:C3 ratio of the incremental LPG produced vs. standard ZSM-5 additives. These additives may be used at very high concentrations to provide a simple and effective route for adjusting FCC LPG olefin production to meet changing market demands.
For refiners who require higher gasoline octane, but are wet gas compressor or gas plant limited or do not desire higher LPG yields, Johnson Matthey offers ISOCAT and OCTAMAX products. These additives are based on ZSM-5 with much higher Silica to Alumina Ratio (SAR) than those grades used to increase propylene selectivity. Higher SAR ZSM-5 results in lower selectivity towards cracking gasoline to LPG while maintaining high isomerization activity that boosts gasoline octane.