Employing modified SBA-15 molecular sieve as the support, iron-promoted Rh catalysts were investigated in the synthesis of ethanol from syngas through temperature programmed surface reaction (TPSR). Addition of promoter in certain range could partially block the rhodium surface, thereby diminishing the number of active sites and resulting in the decrease in CO conversion. However, there is not a continuous decrease in the number of active sites responsible for methane production. There exists an optimum promoter loading at which the ability of rhodium to dissociate the CO molecules is the maximum, i.e., Fe/Rh (weight ratio) = 0.5. (C) 2010 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.