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