Green synthesis of Cu-Mo promoted Fe catalyst for production of the gaseous and liquid fuels through Fischer-Tropsch synthesis

Abstract

Designing a novel Fe catalyst with improved selectivity to light olefins and heavier hydrocarbons attracts great attention for Fischer-Tropsch synthesis (FTS) as an alternative clean energy resource. In this work, a highly efficient Cu-Mo promoted Fe catalysts supported on activated carbon with engineered features from biomass were synthesized and tested for FTS under relevant industrial conditions (300 °C, 2 MPa, and 2000 h−1). Optimization of the Fe, Mo, and Cu loadings led to a significant increase in CO conversion (from 46.7% for unpromoted to 78.8% for Cu-Mo promoted catalysts). Light olefin selectivity for the promoted catalysts was remarkably enhanced to 33.2% and 25.0% for Cu and Mo-promoted catalysts, respectively. The improved selectivity to light olefin can be attributed to the weakened basicity of iron sites for promoted catalysts. Improved C5+ selectivity on the other hand, can be assigned to the contribution of Fe carbides with higher C:Fe ratio in the structure of the optimized catalyst. The presence of Mo carbides was confirmed by XPS, XRD, and XANES results, manifesting the contribution of Mo in the catalytic activity of the optimized catalyst. The superior selectivity to both light olefins and C5+ hydrocarbons disclosed that the prepared catalyst could be an ideal candidate for industrial iron-based FTS catalyst in future to modulate the products distribution.