Abstract
The effects of the surfactant hexadecyltrimethylammonium bromide (CTAB) on the catalytic performance of a manganese-promoted iron (FeMn) catalyst for the Fischer-Tropsch to olefin (FTO) reaction were investigated. The use of the CTAB-assisted FeMn catalyst resulted in the production of light olefin (C(2-4) ([double bond, length as m-dash])) selectivity of up to 55.45% with a ratio of olefin to paraffin among the C(2)-C(4) hydrocarbons as high as 7.75 under industrially relevant conditions (320 °C, 1.0 MPa, H(2)/CO ratio of 1.5 (v/v), GHSV = 4200 h(-1)). The characterization results indicate that CTAB has a great influence on the structure, composition, chemical state, and catalytic performance of the iron-based catalyst. Most interestingly, a greater amount of Mn promoter was found to be dispersed on the surface of α-Fe(2)O(3), rather than being dissolved into the α-Fe(2)O(3) lattice when CTAB was employed, which contributed towards enhancing the promotional effects of the Mn promoter, leading to the formation of certain surface-specific activity sites.