Transformation of syngas to valuable oxygenated products over Rh-MnOx/SiO2, Rh-Co/ZrO2 and Rh-Cu/ZrO2 catalysts

The conversion of syngas into higher alcohols was examined using bimetallic Rh-Co, Rh-Cu, and multimetallic RhCuPd catalysts, all of which were supported on ZrO2. This process was also studied using a MnOx-promoted Rh/SiO2 catalyst. These experiments were conducted within a temperature range of 225–300 °C, under a pressure of 30 bar, and with a H2/CO ratio of 2. The catalysts were characterized using a variety of physicochemical methods, including Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), and Carbon Monoxide Diffuse Reflectance Infrared Fourier Transform Spectroscopy (CO DRIFTS). The Rh particle sizes in the fresh catalysts were found to be less than 3 nm. The Rh-Co catalyst supported on ZrO2 exhibited the highest selectivity to ethanol, achieving 38 % at a CO conversion rate of 58 % at 275 °C. This catalyst also demonstrated a chain growth probability of 0.35 for alcohols. A slightly higher chain growth probability was observed with the Rh-MnOx/SiO2 catalyst, although this also resulted in the formation of substantial amounts of acetic acid. Interestingly, this acetic acid could be converted into ketones when RhMnOx was used in conjunction with Pd/ZrO2. [Display omitted] •Bimetallic zirconia supported Rh-Co, Rh-Cu, and multimetallic RhCuPd catalysts for conversion of syngas into higher alcohols•Extensive catalyst characterization.•38 % selectivity to ethanol at 58 % CO conversion at 275 °C on Rh-Co/ZrO2.•Rh-MnOx/SiO2 catalyst resulted in substantial amounts of acetic acid.•Acetic acid could be converted into ketones when RhMnOx is combined with Pd/ZrO2.