Operational conditions and coke formation on Pt-Al2O3 reforming catalyst

Abstract The influences of pressure, H2 to naphtha ratio, temperature, space velocity and time on coke formation during naphtha reforming over Pt-Al2O3 has been studied. A standard test was used which consisted of operating the catalyst at normal conditions during a first and a third period of 7 h each, and changing to more severe conditions during an intermediate period of 20 h. Correlations between the amount of coke at the end of the test, the changes in octane number and the operational conditions during the severe period were derived. The decrease in octane number depended on1y on the amount of coke and did not depend on how the severity was achieved. The temperature programmed oxidation (obtained by differential thermal analysis) of the used catalysts showed two zones, one from 396 to 642 K and the other from 642 to 828 K. The second zone corresponded to the burning of a more polymerized deposit, the amount of which increased with the severity of the operation much more than the first zone. The thermogram patterns were quite similar and independent of the operational conditions used to deposit the coke.