Maximize octane barrels; adjust reformer charge IBP

Increasing gasoline octane number by optimizing the front end boiling of the reformer charge was studied. Results show that when evaluated on the basis of the yield and octane of the composite reformate plus straight run gasline stream, an advantage is observed with the n-hexane fraction added to the reformer feed, if octane severity, based on reforming the C/sub 7/ + naphtha, is above 93.5 RON, Clear. This advantage is greater as reformer severities are increased. Below 93.5 RON, Clear, a C/sub 7/ + naphtha appears to be the optimum reformer charge. Further lowering of the boiling range to include the isohexanes fraction results in lower overall gasoline yields except at very high reformer severities. This evaluation was made by using a medium quality mid-continent naphtha as a case study. Poorer quality feeds may show even higher yield benefits when using the nC/sub 6/ + naphtha as reformer charge.