Fischer–Tropsch synthesis of CO2-rich syngas using a CoRu-KIT-6 catalyst in a 3D-printed stainless steel (SS) microchannel microreactor†

A CoRu-KIT-6 catalyst, prepared by a one-pot hydrothermal method, was used for Fischer–Tropsch synthesis (FTS) of syngas containing CO₂ in a 3D-printed stainless-steel microchannel microreactor (SSMR) at 20 bar. The catalyst was characterized using N₂ adsorption–desorption isotherm measurement, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), H₂-temperature programmed reduction (H₂-TPR), CO₂-temperature programmed desorption (CO₂-TPD) and X-ray photoelectron spectroscopy (XPS) techniques. While the surface area from the N₂ adsorption–desorption isotherm is quite high (690.4 m² g⁻¹), with low reduction temperatures (H₂-TPR) of the metals, the low-angle XRD, SEM, and TEM studies show that the ordered mesoporous structure of KIT-6 is conserved after the addition of Co and Ru metals. The bimetallic catalyst was used to investigate the effect of reaction temperature and CO₂ concentration (by volume) in feed gas mixtures on the conversion of CO and CO₂ in modified FTS. Four different volume compositions of CO₂/CO/H₂ (10 : 30 : 60, 25 : 25 : 50, 40 : 20 : 40, and 70 : 10 : 20) were used for modified FTS in the temperature range of 210 to 350 °C. While CO₂ conversion increases with rising reaction temperature, CO conversion is adversely affected by the higher CO₂ concentration in the feed. The Co-Ru-KIT-6 catalyst exhibits excellent catalytic activity, achieving higher conversion and hydrocarbon selectivity with CO₂-rich syngas. The CO₂-rich syngas composition (CO₂ : CO : H₂ = 25 : 25 : 50) at 350 °C showed the best result for CO conversion of 82.3%, CO₂ conversion of 28.1% and higher selectivity to longer chain hydrocarbons (C₅₊), 79.1%.