Hydroxyl Regulation Enables Metal Promoter‐Free Iron Catalysts for Highly Efficient CO 2 Hydrogenation to Light Olefins

ABSTRACT The efficient hydrogenation of CO 2 to light olefins over Fe‐based catalysts typically relies on the metal promoters, such as alkali or transition metals. In this study, we find that the intrinsic hydroxyl environments may be the crucial but long‐overlooked factor governing the activity of Fe species. With the assistance of low‐concentration guar gum, hydrogen‐bond networks formed by dense hydroxyls are disrupted to generate isolated or terminal hydroxyl groups, which increase the active sites and significantly facilitate the product desorption. The resulting metal promoter‐free Fe achieves a CO 2 conversion of 30.1% and a light olefin selectivity of 38.1% at an ultra‐high gas hourly space velocity of 300 000 mL g cat −1 h −1 . Meanwhile, the space‐time yield of light olefins reaches 3.3 kg kg cat −1 h −1 , which outperforms all of the reported Fe‐based catalysts modified by various promoters. These findings redefine hydroxyls as intrinsic promoters in Fe catalysts for CO 2 hydrogenation and can potentially be extended to other heterogeneous catalytic systems and reactions.