Octane catalysts operating changes

The catalyst, 50% M/H-ZSM-5 and 50% alumina, was supplied by INTEVEP S.A. as 1/16 inch diameter cylinders. Its catalytic properties (activity, yield and selectivity) was studied in an isothermal fixed bed reactor operated under hydrogen atmosphere keeping the ratio of H/n-C8 always equal to 42.06. Deactivation tests were done under hydrogen atmosphere and at the following reaction conditions WWH = 2.87 h, T = 280°C, P = 200 psig., until a stable activity level or a complete deactivation was reached. For pure n-octane transformation over a stabilized catalyst, the change in products distribution with contact time, fi om 0.2 to 2 h, and with reaction temperatures, fi om 200 to 470°C, was also studied [9]. 

By avoiding the acid catalysis mechanism of the conventional FCC zeolite catalyst (optimized over the years for high octane gasoline), the novel MAB catalyst will produce substantially lower aromatics in the liquid products than is possible by less extreme FCC catalyst adaptations. By changing the FCC reaction system, it is possible to overcome the MAB catalyst low activity drawback and achieve slurry yields compatible with those observed in maximum distillate operation in today s FCC units. 

For PtSn supported on a nonacidic alumina the addition of Sn causes an increase in activity up to Sn/Pt = 4, and then a decline in activity for low pressure operation (42). The increase in activity is much less at 400 psig operation than the two-fold increase observed at atmospheric pressure. However, there is a change in the selectivity of aromatic isomers produced from n-octane at both 15 and 400 psig as Sn is incorporated into the catalyst. Thus, both Pt and Pt/Sn catalysts produce only (> 90-95%) ethylbenzene and o-xylene as the dehydrocyclization products from n-octane. However, Pt produces ethylbenzene o-xylene = 1 1 whereas a catalyst with Sn/Pt = 4 produces ethylbenzene o-xylene = 1 2. This change in aromatic isomerization leads to two postulates ... 

Reactor Temperature. The primary control for product quality in the Platforming process is the temperature of the catalyst beds. Platforming catalysts are capable of operating over a wide range of temperatures. By adjusting the heater outlet temperatures, a refiner can change the octane of reformate and the quantity of aromatics produced. 

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