Minimizing CO2 production during Syngas Catalysis Mediated By Nano-Sized Iron Supported on Silica Spheres

Minimizing CO₂ prodcution in chemical reactions is a desirable pathway to low-carbon processes. Our approach encompasses two aspects: 1) use nano-sized catalysts to enhance surface area to achieve increased space-time-yield (STY) and couple it with 2) slurry phase for better heat management. For this study, we selected well-known iron mediated Fischer-Tropsch (F-T) synthesis as the test reaction due to issues with product selectivity and catalyst activity and the fact that CO₂ is a major side product in conventional F-T reaction. In the study, three a-Fe₂O₃-based catalyst precursors were evlauted: 1) an unsupported nano-sized (20-80 nm) BASF material, 2) a micrometer-sized (32.5 µm) UCI supported on gamma alumina and doped with potassium as a reference, 3) a core-shell configuration consisting of silica microspeheres (500 nm) as the core and about 20 nm iron oxide as the shell. All three materials were evaluated in a 300 mL Parr batch reactor for F-T synthesis at three temperastures with the goal to shut-sown water-gas-shift (WGS) reaction that is the cause of CO₂ prodcution. The F-T data were collected by feeding synthesis gas (syngas) with H₂/CO ratio of 2.

The presentation will first focus on key steps of the core-shell nano-sized material synthesis and its characterization using a suite of spectroscopic techniques including Transmission Electron Microscopy and Raman. Then, its perfornace under F-T synthesis reaction will be discussed for CO₂ minimization relative to desired hydrocarbon products, thus enhancing overall carbon conversion. We will present morphology and structural characterization data and full mass balance by analyzing gas and liquid products of each run. A relationship between structural properties and reaction parameters to achieve low CO₂ or non-CO₂ production scenarios will be discussed.