High performance Ni-Fe-Mg catalyst for tar removal in producer gas

A Ni-Fe-Mg material, supported on a ceramic substrate, suitable for application in a gasifier or reforming reactor was evaluated as a catalyst for tar decomposition via steam reforming. Experiments were conducted in a laboratory -scale fixed -bed reactor using simulated producer gas containing toluene and ethylene as tar surrogates. The catalyst was prepared by wet -impregnation and characterized by analytical techniques to include: BET, XRD, TPR, and SEM. The elemental composition of Ni, Fe, and MgO was optimized for maximum activity and stability. The optimized catalyst composition contained Ni, Fe, and MgO in the ratio 45:21:34 by weight. The observed catalyst activity was superior in comparison to other alkaline earth metal promoters: CaO, SrO, and BaO as well as a reference catalyst, Ni-K-MgO, in the temperature range between 600 and 800 degrees C. Time on stream with the optimized composition showed sustained tar (toluene + ethylene) conversion of near 100% at 750 degrees C for at least 48 h, indicating no coke formation. The coke formation affinity of Ni was reduced by the presence of the FeNi3 alloy. The enhanced performance with MgO is attributed to the strong adsorption of H2O forming Mg (OH)(2) species facilitated on the oxide ion vacancy site of MgO acting as oxygen exchange site.