Fatty acid decarboxylation reaction kinetics and pathway of co-conversion with amino acid on supported iron oxide catalysts

摘要

Fe2O3/Al-MCM-41 nanocomposite catalysts were designed and fabricated to upgrade microalgae hydrothermal liquefaction (HTL)-derived biocrude and its model compounds (palmitic acid and glutamic acid) in the absence of hydrogen. The Fe2O3/Al-MCM-41 catalysts were prepared by encapsulating Fe2O3 particles on highly stable pure silica MCM-41 and Al-MCM-41. XRD, TEM, N-2 adsorption isotherms, XPS, and UV-Vis characterizations of the catalysts revealed that 10-30 nm g-Fe2O3 particles were well dispersed on the mesoporous support. In the range of 320-350 degrees C and under subcritical water, palmitic acid conversion was improved by 43-54% by the Fe2O3/Al-MCM-41 catalyst. The overall reaction rate was first order to palmitic acid for non-catalytic and catalytic conversions, and the activation energy was 336.76 kJ mol (1) for Fe2O3/Al-MCM-41. In situ DRIFTS reaction test demonstrated that the initiation temperature for the catalytic decarboxylation of palmitic acid was decreased to 195 degrees C, and desorption of the produced CO2 occurred at 255 degrees C. Based on the GC-MS results of the HTL products, the reaction pathway of the binary mixture of palmitic acid and glutamic acid was elucidated, and the chemical origins of amide, pyrrolidinone, hydroxy-butanoic acid, and pentadecane were proposed.