Direct Conversion of Syngas to Light Olefins through Fischer-Tropsch Synthesis over Fe-Zr Catalysts Modified with Sodium

Production of Light Olefins via Fischer-Tropsch Process Using Iron-Based Catalysts: A Review

The production of light olefins, as the critical components in chemical industries, is possible via different technologies. The Fischer–Tropsch to olefin (FTO) process aims to convert syngas to light olefins with high selectivity over a proper catalyst, reduce methane formation, and avoid the production of excess CO2. This review describes the production of light olefins through the FTO process using both unsupported and supported iron-based catalysts. The catalytic properties and performances of both the promoted and bimetallic unsupported catalysts are reviewed. The effect of support and its physico-chemical properties on the catalyst activity are also described. The proper catalyst should have high stability to provide long-term performance without reducing the activity and selectivity towards the desired product. The good dispersion of active metals on the surface, proper porosity, optimized metal-support interaction, a high degree of reducibility, and providing a sufficient active phase for the reaction are important parameters affecting the reaction. The selection of the suitable catalyst with enhanced activity and the optimum process conditions can increase the possibility of the FTO reaction for light-olefins production. The production of light olefins via the FTO process over iron-based catalysts is a promising method, as iron is cheap, shows higher resistance to sulfur, and has a higher WGS activity which can be helpful for the feed gas with a low H2/CO ratio, and also has higher selectivity towards light olefins.

Effect of the Zr promoter on precipitated iron-based catalysts for high-temperature Fischer–Tropsch synthesis of light olefins

FeMnxZr and FeMnxZr2Na catalysts prepared by coprecipitation and impregnation methods were applied to investigate the promoting effects of Zr on iron-based catalysts for high-temperature Fischer–Tropsch synthesis (HTFT).

Selective Conversion of Syngas to Olefins via Novel Cu-Promoted Fe/RGO and Fe-Mn/RGO Fischer-Tropsch Catalysts: Fixed-Bed Reactor vs Slurry-Bed Reactor

Fischer-Tropsch has become an indispensable choice in the gas-to-liquid conversion reactions to produce a wide range of petrochemicals using recently emerging biomass or other types of feedstock such as coal or natural gas. Herein we report the incorporation of novel Cu nanoparticles with two Fischer-Tropsch synthesis (FTS) catalytic systems, Fe/reduced graphene oxide (rGO) and Fe-Mn/rGO, to evaluate their FTS performance and olefin productivity in two types of reactors: slurry-bed reactor (SBR) and fixed-bed reactor (FBR). Four catalysts were compared and investigated, namely Fe, FeCu7, FeMn10Cu7, and FeMn16, which were highly dispersed over reduced graphene oxide nanosheets. The catalysts were first characterized by transmission electron microscopy (TEM), nitrogen physisorption, X-ray fluorescence (XRF), X-ray diffraction (XRD), and H-TPR techniques. In the SBR, Cu enhanced olefinity only when used alone in FeCu7 without Mn promotion. When used with Mn, the olefin yield was not changed, but light olefins decreased slightly at the expense of heavier olefins. In the FBR system, Cu as a reduction promoter improved the catalyst activity. It increased the olefin yield mainly due to increased activity, even if the CO2 decreased by the action of Cu promoters. The olefinity of the product was improved by Cu promotion but it did not exceed the landmark made by FeMn16 at 320 °C. The paraffinity was also enhanced by Cu promotion especially in the presence of Mn, indicating a strong synergistic effect. Cu was found to be better than Mn in enhancing the paraffin yield, while Mn is a better olefin yield enhancer. Finally, Cu promotion was found to enhance the selectivity towards light olefins C2-4. This study gives a deep insight into the effect of different highly dispersed FTS catalyst systems on the olefin hydrocarbon productivity and selectivity in two major types of FTS reactors.