Synthesis of ethanol from syngas over iron-promoted Rh immobilized on modified SBA-15 molecular sieve: Effect of iron loading

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.

Research highlights▶ TPSR technique presents how Fe promoter suppressed methanation activity over Rh-based catalysts. ▶ Upon increasing Fe loading, methane peak area reached a maximum at about Fe/Rh (weight ratio) = 0.5, then the methane formation was suppressed at higher promoter loading. ▶ Appropriate Fe/Rh ratio can afford optimal ability of rhodium to dissociate the CO molecules to the highest extent.