Study of Different H2/CO2 Ratios as Feed in Fischer-Tropsch Reactor with Iron-Based Nano-Hydrotalcite Catalysts

Abstract

CO₂-FTS is among the most viable methods for converting CO₂ into useful chemicals and fuels in order to minimize CO₂ emissions. Due to its chemical inertness, however, effective conversion continues to be a difficulty. The challenges in terms of yield and mechanism have attracted the interest of different research groups in the development of a new carbon dioxide hydrogenation catalysts, capable of reaching satisfactory results. In this work, a selection of nano ternary hydrotalcites (HTlc) were synthesized with and without ultrasound in order to develop active Fe-based catalysts for the Fischer–Tropsch synthesis. HTlc consists mostly of metal hydroxides in which different metal atoms are uniformly distributed at the atomic level. The reaction was carried in a lab scale plant in a fixed bed configuration. All fresh and used catalysts were examined and characterized using XRPD, ICP-OES, SEM, TEM, BET. Ternary HTlc composed of Mg, Cu, and Fe was synthesized using an ultrasound-assisted co-precipitation technique (MCF-US). HTlc was tested for carbon dioxide hydrogenation reaction with a study concerning different H₂/CO₂ ratios in order to evaluate the product distribution as well as the efficiency of the catalyst itself. The CO₂ conversion resulted higher and more stable in feeds with higher H₂ quantities. The selectivity towards higher chain hydrocarbons was higher for lower H₂/CO₂ ratios whereas methane and carbon monoxide selectivities were adequately low.