Endothermic Reforming of n-Hexane on Metal (Pt, Ga) Containing H-ZSM-5 at High Pressures

The supercritical, high-pressure reaction of n-hexane over H-ZSM-5, with, and without the addition of Pt and Ga, has been studied for application to endothermic reforming in scramjet engines. The endothermicities of the reactions were determined from the product distributions. For unpromoted H-ZSM-5, the product distribution indicated that the endothermicity is low and decreases with increasing pressure. The addition of Ga to H-ZSM-5 has a relatively small effect on n-hexane conversion but significantly increases the endothermicity of the reaction by increasing the selectivity to form small aromatics. The H(Ga)-ZSM-5 catalyst showed no deactivation for at least 5 h at 633 K and 137 bar of n-hexane. By contrast, the addition of Pt had a minor effect on both the rate and the reaction endothermicity.