Abstract: In this paper, the supported MoO₃/Al₂O₃ ultrafine catalysts have been synthesized with the supercritical drying method.The n-heptane reforming reaction has been used as a model reaction, the different qualities between the ultrafine and the conventional catalysts have been discussed, the ultrafine MoO₃/Al₂O₃ catalysts have more stability than the conventional catalysts, this is because there are much more strong reactions between the active component and support as well as less volatility of active component.The ultrafine catalysts have less cracking conversion and selectivity, this is because there are weak acid centers on the Al₂O₃ surface.

Key words: Supercritical drying, Ultrafine catalyst, Supported MoO₃/Al₂O₃ catalyst