n-Heptane hydroconversion over sulfated-zirconia-supported molybdenum carbide catalysts

Molybdenum carbide on sulfated zirconia was prepared by impregnation of MoO3 on sulfated zirconia to give a loading of 5 wt% followed by carburisation at 923 K in a mixture of CH4/H2 (4:1). The resulting catalyst was characterised by N2 adsorption–desorption, CO chemisorption, FTIR of pyridine adsorption, XRD, TPR, TGA, Raman and SEM–EDX. This combination of characterisation studies suggests formation of a well-dispersed Mo2C phase over tetragonal zirconia. When employed in the hydroconversion of n-heptane, high temperature and low space velocity lead to substantial cracking. However, under some conditions, an increase in the research octane number (RON) from 0 (n-heptane) to ca. 50 was attained. Between 723 and 873 K, n-heptane is mainly cracked to iso-pentane and ethane. The product distribution as a function of conversion suggests that the reaction did not simply follow a consecutive reaction pathway, but that other parallel routes were involved.