Iron catalyst encapsulated in carbon nanotubes for CO hydrogenation to light olefins

Abstract

Fe-based catalyst is an outstanding candidate for the Fischer-Tropsch reaction to get light olefins from syngas directly. However, exposed Fe species are susceptible to sintering and coking, which lead to deactivation. Here, we demonstrate that Fe nanoparticles encapsulated in pod-like carbon nanotubes (Pod–Fe) can be used as an efficient Fischer-Tropsch catalyst to produce light olefins. It gave a higher selectivity of light olefins (45%) and high stability over 120 h reaction (P = 0.5 MPa, T = 320 °C, CO:H2 = 1:2, gas hourly space velocity = 3500 h−1). A catalyst with exposed Fe particles on the outside of the Pod-Fe (FeOx/Pod-Fe) catalyst showed a selectivity of light olefins of 42%, but had a significantly lower stability due to the agglomeration of Fe nanoparticles and carbon deposition. These results indicated that the graphene shell of Pod-Fe played an important role in protecting the Fe particles and provided a rational way to enhance the activity and stability of Fe-based catalysts in high temperature reactions.