Effect of iron loading on acidity and performance of Fe/HZSM-5 catalyst for direct synthesis of aromatics from syngas

A bifunctional Fe/HZSM-5 catalyst was prepared for direct synthesis of aromatics from syngas. The influence of iron loading on acidity and syngas to aromatics (STA) performances over the Fe/HZSM-5 catalysts was studied. An increasing iron loading increased the amounts of active iron species, enhancing synergistic effect of active iron sites and HZSM-5 for the STA reaction. Higher iron loading in the Fe/HZSM-5 catalyst resulted in the decrease of Brönsted acid sites and increase of Lewis acid sites, promoting the formation of C5+ hydrocarbons and aromatics selectivity via weakening the cracking ability and enhancing the dehydrogenation property of HZSM-5. Excessive adding of iron loading induced the formation of graphitic carbon deposition, leading to a decrease of catalytic activity and stability.