(406e) Mixed (dry & partial oxidation) Reforming of Methane with a New Catalyst Derived from a Negative Value Mining Residue Spinellized with Nickel

Frank DEGA⁽⁺⁾, Mostafa CHAMOUMI, Nadi BRAIDY and Nicolas ABATZOGLOU^(*)

Department of Chemical Engineering and Biotechnological Engineering, Université de Sherbrooke, Sherbrooke, QC, J1K 2R1, Canada

Key words: spinel, reforming, catalyst, nickel, carbon deposition, stability, selectivity.

⁽⁺⁾ Presenting author: Frank.Blondel.Dega.Dongmo@USherbrooke.ca

^(*) Corresponding author: Nicolas.Abatzoglou@USherbrooke.ca

This work belongs to a larger endeavor aimed at studying the performance and the stability of a hydrocarbons reforming spinellized nickel catalyst prepared from an ilmenite metallurgical residue. Said residue is a negative value upgraded slag oxide (UGSO) coming from a TiO₂ slag production unit, operated by Rio Tinto Iron & Titanium, Quebec, Canada. Recently published results from experiments carried out with this catalyst exhibited high hydrogen production selectivity during methane steam and dry (CO₂) reforming and stability over time-on-stream (TOS).

More specifically, this work report on the behavior of this catalytic formulation during methane partial oxidation (POX) regimes employing both CO₂ and O₂ as reactants. This has been done at 800-850°C, atmospheric pressure, molar ratios CH₄/CO₂ = 3, CH₄/O₂ = 1, 2, 3, and a space velocity between 4000 and 4600 ml_STP/h/g_cat. The conversion of CH₄ and CO₂ and the selectivity of H₂and CO have been assessed by means of mass balances whose closure is 100 +/-5%. The crystalline phases of the catalyst components as well as their changes over TOS in presence of different oxygen concentration have been studied. A first attempt to correlate the catalytic performances and the catalytic stability (mainly related to carbon deposition tendency) with the mechanisms and structural modifications of the catalyst over TOS is reported.

The promising results have shown that, within the experimental range tested, an optimum performance has been obtained at 850°C and at molar CH₄/CO₂ = 3, CH₄/O₂ = 2. At CH₄/O₂ lower and higher than 2 the catalytic performance decreases. The catalyst exhibited a good stability for 2 days of reaction, with no detectable carbon deposition, high conversions (99% of CH₄, 62% of CO₂) and H₂ selectivity of 60%. The in situ X-ray diffraction (XRD) analysis showed that the crystalline structure of the catalyst is subject to modifications. The most significant observation is that the catalyst structure changes over, typically, the first 30min of TOS then stabilizes. This catalyst structure behavior has been correlated to its good stability, the absence of carbon deposition and the high methane conversion and hydrogen selectivity. This study sheds more light on the role of the reaction environment in the activity and the stability of this UGSO spinellized nickel catalyst.