J.A. Botas et al. discuss the catalytic conversion of vegetable oils into hydrocarbons suitable for use as biofuels (Catal. Today, 2012, 195, 59). What are the most important features of catalysts that are used for these reactions? How was the incorporation of transition metals expected to modify catalyst properties? Outline how the modified catalysts were prepared and characterized. What reactions occurred in the reactor in addition to catalytic cracking? Which reactions led to aromatic products? Which of the modified catalysts produced most coke build-up? Explain why this did not deactivate the catalyst.