Synthesis Gas Production by Methane Partial Oxidation on Ni/Fe₃O₄-Ce_0.75Zr_0.25O₂ Catalysts: Kinetic Study

Abstract

Fe3O4-Ce0.75Zr0.25O2 (FeCZ) is an oxygen carrier material aimed to produce syngas through methane partial oxidation in absence of oxygen gas feed. The objective of the present research is to study the catalytic effect of Ni on FeCZ using an evaluation of the global kinetics (activation energy, reaction rate, order and constant) of its reaction with methane for syngas production. FeCZ and 0.05NiFeCZ (Ni/Fe = 0.05 molar ratio) were synthesized through co-precipitation of their precursor nitrate salts, while 2NiFeCZ was prepared by impregnation of FeCZ with a nickel nitrate solution to obtain a 2 %W Ni material. Samples were calcined at 950°C during 4 hours in air. Kinetic study of oxygen carriers (FeCZ, 0.05NiFeCZ and 2NiFeCZ) reduction with methane was followed through thermogravimetric analysis (TGA) at 5, 7.5 and 10% CH4/Ar and 600, 650 and 700°C. Initial reaction rate was obtained from the slope of the linear region of the weight change signal as a function of time. Results indicate a first order global reaction rate for all materials. Activation energies for samples FeCZ, 0.05NiFeCZ and 2NiFeCZ were 52.2, 39.5 and 28.3 Kcal/mol, respectively. Thus, reflecting the catalytic effect of Ni over the FeCZ global reaction rate.

Thermogravimetric kinetic analysis of the Ce‐Zr composite oxygen carrier prepared by ball milling

“…Hosseini et al [ 15 ] reported the range of activation energies as 60–81 kJ/mol for CeO 2 ‐Fe 2 O 3 oxygen carriers with low or moderate Fe content using a phase boundary‐controlled model. Sosa Vazquez et al [ 16 ] used TGA to investigate the reduction kinetics of three oxygen carriers, namely, Fe 3 O 4 ‐Ce 0.75 Zr 0.25 O 2 (FeCZ), 0.05NiFeCZ (Ni/Fe = 0.05 molar ratio), and 2NiFeCZ. The results indicated that the overall reaction rate of all materials was the first level, and the activation energies of FeCZ, 0.05NiFeCZ, and 2NiFeCZ were 218.4, 165.3, and 118.4 kJ/mol, respectively.…”