Enhanced oil and gas products in fast coal pyrolysis over iron oxide using infrared heating

This study investigates the influence of iron oxide on the pyrolysis behavior of coal under varying heating methods, specifically infrared heating (IH) and electric heating (EH). Comprehensive analyses were conducted using TG-FTIR, GC-MS, XRD, FTIR, and Raman spectroscopy to elucidate the changes in pyrolysis product distribution, char structure, and functional group composition across different temperatures. The addition of iron oxide as a catalyst in coal pyrolysis significantly enhanced oil yield at temperatures below 600 °C and increased gas production across all temperatures. The gas composition showed improved heating value, with elevated levels of CH₄, H₂, and CO, and reduced CO₂ formation. GC-MS analysis indicated that iron oxide promoted the generation of valuable aliphatic hydrocarbons and alcohols while minimizing the production of undesirable acids in the pyrolysis oil. Compared to EH, IH resulted in higher oil yields and lower water yields by facilitating greater cross-interaction between volatiles. Additionally, IH favored the production of aliphatic hydrocarbons and phenols while suppressing acid formation as temperatures increased. XRD analysis further revealed that IH predominantly yielded Fe₃O₄ in the char at lower temperatures, suggesting that IH effectively inhibited the reduction of Fe₃O₄ by non-condensable gases, thus preserving the gas products.